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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Feb. 25, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	ANAPTYSBIO INC
Entity Central Index Key	0001370053
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		26,986,584
Entity Public Float			$ 1,518,810,407
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 113,596	$ 81,189
Australian tax incentive receivable	174	1,601
Short-term investments	313,486	167,218
Prepaid expenses and other current assets	6,960	2,688
Total current assets	434,216	252,696
Property and equipment, net	1,445	665
Long-term investments	73,128	75,897
Other long-term assets	148	46
Restricted cash	60	60
Total assets	508,997	329,364
Current liabilities:
Accounts payable	5,443	2,323
Accrued expenses	8,761	4,875
Notes payable, current portion	7,574	6,875
Other current liabilities	58	17
Total current liabilities	21,836	14,090
Notes payable, net of current portion	625	7,553
Deferred rent	171	140
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000 shares authorized and no shares, issued or outstanding at December 31, 2018 and December 31, 2017, respectively	0	0
Common stock, $0.001 par value, 500,000 shares authorized, 26,922 shares and 23,791 shares issued and outstanding at December 31, 2018 and December 31, 2017, respectively	27	24
Additional paid in capital	633,251	393,017
Accumulated other comprehensive loss	(223)	(426)
Accumulated deficit	(146,690)	(85,034)
Total stockholders’ equity	486,365	307,581
Total liabilities, preferred stock and stockholders’ equity	$ 508,997	$ 329,364

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	26,921,822	23,791,000
Common stock, shares outstanding (in shares)	26,921,822	23,791,000

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Collaboration revenue	$ 5,000	$ 10,000	$ 16,684
Operating expenses:
Research and development	56,196	29,443	15,419
General and administrative	15,526	9,338	4,290
Total operating expenses	71,722	38,781	19,709
Loss from operations	(66,722)	(28,781)	(3,025)
Other income (expense), net:
Interest expense	(1,652)	(1,775)	(458)
Change in fair value of liability for preferred stock warrants	0	(1,366)	(756)
Interest income	6,685	1,623	127
Other (expense) income, net	(159)	229	(147)
Total other income (expense), net	4,874	(1,289)	(1,234)
Loss before income taxes	(61,848)	(30,070)	(4,259)
Provision for income taxes	192	0	0
Net loss	(61,656)	(30,070)	(4,259)
Other comprehensive income (loss):
Unrealized income (loss) on available for sale securities	258	(426)	0
Income tax expense related to other comprehensive income	(55)	0	0
Other comprehensive income (loss), net of tax	203	(426)	0
Comprehensive loss	$ (61,453)	$ (30,496)	$ (4,259)
Net loss per common share:
Basic and diluted (in dollars per share)	$ (2.50)	$ (1.52)	$ (1.62)
Weighted-average number of shares outstanding:
Basic and diluted (in shares)	24,673	19,782	2,637

CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Preferred Stock Series B convertible preferred stock	Preferred Stock Series C convertible preferred stock	Preferred Stock Series C-1 convertible preferred stock	Preferred Stock Series D convertible preferred stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Stockholders' Equity, Beginning Balance at Dec. 31, 2015	$ (35,179)	$ 28,220	$ 6,452	$ 2,156	$ 40,688	$ 3	$ 15,482	$ 0	$ (50,664)
Shares, Outstanding, Beginning Balance at Dec. 31, 2015		3,963,000	1,593,000	474,000	5,491,000	2,630,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under employee stock plans	31						31
Shares issued under employee stock plans (in shares)						23,000
Repurchase of shares	$ (1)						(1)
Repurchase of shares (in shares)	(1,457)					(2,000)
Stock-based compensation	$ 1,160						1,160
Net loss	(4,259)								(4,259)
Stockholders' Equity, Ending Balance at Dec. 31, 2016	(38,248)	$ 28,220	$ 6,452	$ 2,156	$ 40,688	$ 3	16,672	0	(54,923)
Shares, Outstanding, Ending Balance at Dec. 31, 2016		3,963,000	1,593,000	474,000	5,491,000	2,651,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for public offerings, net of underwriters' fees	292,537					$ 9	292,528
Stock issued during period (in shares)						9,021,000
Shares issued under employee stock plans	$ 979						979
Shares issued under employee stock plans (in shares)						199,000
Repurchase of shares (in shares)	0
Total offering costs	$ (4,228)						(4,228)
Conversion of preferred stock	77,516	$ (28,220)	$ (6,452)	$ (2,156)	$ (40,688)	$ 12	77,504
Conversion of preferred stock (in shares)		(3,963,000)	(1,593,000)	(474,000)	(5,491,000)	11,521,000
Warrants exercised	536						536
Warrants exercised (in shares)						399,000
Reclassification of warrants	4,607						4,607
Forfeiture rate adjustment	0						41		(41)
Stock-based compensation	4,378						4,378
Comprehensive income (loss)	(426)							(426)
Net loss	(30,070)								(30,070)
Stockholders' Equity, Ending Balance at Dec. 31, 2017	307,581	$ 0	$ 0	$ 0	$ 0	$ 24	393,017	(426)	(85,034)
Shares, Outstanding, Ending Balance at Dec. 31, 2017		0	0	0	0	23,791,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for public offerings, net of underwriters' fees	227,476					$ 3	227,473
Stock issued during period (in shares)						2,530,000
Shares issued under employee stock plans	$ 2,869						2,869
Shares issued under employee stock plans (in shares)	583,660					584,000
Repurchase of shares (in shares)	0
Total offering costs	$ (145)						(145)
Warrants exercised	76						76
Warrants exercised (in shares)						17,000
Stock-based compensation	9,961						9,961
Comprehensive income (loss)	203							203
Net loss	(61,656)								(61,656)
Stockholders' Equity, Ending Balance at Dec. 31, 2018	$ 486,365	$ 0	$ 0	$ 0	$ 0	$ 27	$ 633,251	$ (223)	$ (146,690)
Shares, Outstanding, Ending Balance at Dec. 31, 2018		0	0	0	0	26,922,000

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (61,656)	$ (30,070)	$ (4,259)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	315	183	233
Stock-based compensation	9,961	4,378	1,160
Change in fair value of liability for preferred stock warrants	0	1,366	756
(Income) loss from investments	(1,233)	11	0
Non-cash interest expense	646	619	105
Loss on disposal of property and equipment	0	0	1
Changes in operating assets and liabilities:
Receivable from collaborative partners	0	1,225	1
Australian tax incentive receivable	1,427	2,517	(4,118)
Prepaid expenses and other assets	(5,188)	(1,885)	(1,079)
Accounts payable and other liabilities	7,083	2,218	1,251
Income taxes	139	0	(139)
Deferred revenue	0	0	(2,942)
Net cash used in operating activities	(48,506)	(19,438)	(9,030)
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of investments	(347,537)	(290,905)	0
Sales and maturities of investments	206,149	48,137	0
Purchases of property and equipment	(1,063)	(290)	(50)
Net cash used in investing activities	(142,451)	(243,058)	(50)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from public offerings, net of underwriters' fees	227,476	292,537	0
Proceeds from issuance of common stock, upon the exercise of stock options	2,869	979	31
Proceeds from issuance of common stock, upon the exercise of warrants	76	536	0
Payments on notes payable	(6,875)	0	0
Proceeds from debt	0	0	10,000
Payments for repurchase of common stock	0	0	(1)
Payments of Stock Issuance Costs	182	1,599	1,147
Payments for debt issuance costs	0	0	(255)
Net cash provided by financing activities	223,364	292,453	8,628
Net increase (decrease) in cash, cash equivalents, and restricted cash	32,407	29,957	(452)
Cash, cash equivalents and restricted cash, beginning of period	81,249	51,292	51,744
Cash, cash equivalents and restricted cash, end of period	113,656	81,249	51,292
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Interest paid	1,043	1,089	354
Non-cash investing and financing activities:
Fair value of warrants issued with debt	0	0	936
Amounts accrued for property and equipment	159	191	104
Amounts accrued for offering costs	0	37	849
Reclassification of warrants to equity	$ 0	$ 4,607	$ 0

Description of the Business	12 Months Ended
Description of the Business	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business	Description of the Business AnaptysBio, Inc. (“we,” “us,” “our,” or the “Company”) was incorporated in the state of Delaware in November 2005. We are a biotechnology company developing first-in-class antibody product candidates focused on unmet medical needs in inflammation. We develop our product candidates using our proprietary, antibody discovery technology platform, which is designed to replicate, in vitro, the natural process of antibody generation. We currently generate revenue from milestones achieved under our collaborative research and development arrangements. Since our inception, we have devoted our primary effort to raising capital and research and development activities. Our financial support has been provided primarily from the sale of our common and preferred stock, as well as through funds received under our collaborative research and development agreements, proceeds from our Term Loans as discussed in Note 5 below, and the issuance of convertible debt. Going forward, as we continue our expansion, we may seek additional financing and/or strategic investments. However, there can be no assurance that any additional financing or strategic investments will be available to us on acceptable terms, if at all. If events or circumstances occur such that we do not obtain additional funding, we will most likely be required to reduce our plans and/or certain discretionary spending, which could have a material adverse effect on our ability to achieve our intended business objectives. Management believes its currently available resources will provide sufficient funds to enable the Company to meet its operating plans for at least the next twelve months. The accompanying consolidated financial statements do not include any adjustments that might be necessary if we are unable to continue as a going concern. Public Offerings and Related Transactions Initial Public Offering On January 31, 2017, we completed an initial public offering, or IPO, selling 5,750,000 shares, which included the exercise of the underwriters’ option to purchase an additional 750,000 shares of common stock, at $15.00 per share. Proceeds from our initial public offering net of underwriting discounts and commissions were $80.2 million. In addition, each of the following occurred in connection with the completion of the IPO on January 31, 2017: • the conversion of all outstanding shares of convertible preferred stock into 11,520,698 shares of common stock; and • the conversion of warrants to purchase 377,195 shares of convertible preferred stock into warrants to purchase 377,195 shares of common stock and the resultant reclassification of the warrant liability to additional paid-in capital. Reverse Stock Split On January 13, 2017, we amended and restated our certificate of incorporation to effect a one for seven reverse stock split of every outstanding share of our preferred and common stock. The financial statements and accompanying footnotes have been retroactively restated to reflect the reverse stock split. Follow-on Public Offerings On October 17, 2017, we completed an underwritten public offering selling 3,000,000 shares of common stock. All shares were offered by us at a price to the public of $68.50 per share. The aggregate net proceeds received by us from the offering were $194.7 million, net of underwriting discounts and commissions. As part of the underwritten public offering, on November 14, 2017, the underwriters exercised an additional 271,380 shares of common stock at a discounted price to the public of $68.50 per share for aggregate net proceeds of $17.6 million, net of underwriting discounts and commissions. On September 28, 2018, we completed an underwritten public offering of 2,530,000 shares of common stock, which included the exercise of the underwriters’ option to purchase an additional 330,000 shares of common stock. All shares were offered by us at a price to the public of $94.46 per share. The aggregate net proceeds received by us from the offering were $227.5 million, net of underwriting discounts and commissions.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC. The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America, or U.S. GAAP.

Basis of Consolidation

The accompanying consolidated financial statements include us and our wholly-owned Australian subsidiary. All intercompany accounts and transactions have been eliminated in consolidation. We operate in one reportable segment and our functional and reporting currency is the U.S. dollar.

Use of Estimates

The preparation of the accompanying consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. We base our estimates and assumptions on historical experience when available and on various factors that we believe to be reasonable under the circumstances. We evaluate our estimates and assumptions on an ongoing basis. Our actual results could differ from these estimates under different assumptions or conditions.

Cash and Cash Equivalents

We consider all highly liquid investments with a maturity at date of purchase of three months or less to be cash equivalents. Cash equivalents consist primarily of money market and mutual funds with original maturities of 90 days or less.

Restricted Cash

We held restricted cash of $60,000 at December 31, 2018 and 2017, respectively, which we used to secure a letter of credit provided as security for our operating lease for our corporate headquarters.

Short Term and Long Term Investments

All investments have been classified as “available-for-sale” and are carried at fair value as determined based upon quoted market prices or pricing models for similar securities at period end. Investments with contractual maturities less than 12 months at the balance sheet date are considered short-term investments. Those investments with contractual maturities 12 months or greater at the balance sheet date are considered long-term investments. Unrealized gains and losses, deemed temporary in nature, are reported as a component of accumulated other comprehensive income (loss). A decline in the fair value of any security below cost that is deemed other than temporary results in a charge to earnings and the corresponding establishment of a new cost basis for the security. Dividend and interest income are recognized when earned. Realized gains and losses are included in earnings and are derived using the specific identification method for determining the cost of securities sold.

Concentration of Credit Risk

Financial instruments that potentially subject us to a concentration of credit risk consist of cash and cash equivalents and certain investments in money market funds, certificates of deposit, agency securities, commercial obligations and U.S. treasury securities. Bank deposits are diversified between three financial institutions and these deposits may exceed insured limits. We are exposed to credit risk in the event of default by the financial institutions holding our cash and cash equivalents and issuers of investments that are recorded on our consolidated balance sheets. We mitigate our risk by investing in high-grade instruments and limiting the concentration in any one issuer, which limits our exposure.

Property and Equipment

Property and equipment are stated at cost, less accumulated depreciation. Expenditures for major additions and betterments are capitalized. Maintenance and repairs are charged to operations as incurred. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets, which range from three to seven years. Leasehold improvements are amortized using the straight line method over the term of the lease. Upon sale or retirement of property and equipment, the related cost and accumulated depreciation are removed from the accounts and any gain or loss is reflected in operations.

Long Lived Assets

Long-lived assets, consisting of property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable based on undiscounted cash flows. If long-lived assets are impaired, an impairment loss is recognized and is measured as the amount by which the carrying value exceeds the estimated fair value of the assets. No impairment charges were recorded during the years ended December 31, 2018, 2017, or 2016.

Leases, Deferred Rent and Operating Lease Incentives

Our office leases are classified as operating leases. Rent expense is recognized on a straight-line basis over the terms of the leases and, accordingly, we record the cumulative difference between cash rent payments and the recognition of rent expense as a deferred rent liability. When an operating lease includes lease incentives, such as a rent abatements or leasehold improvement allowances, or requires fixed escalations of the minimum lease payments, the aggregate rental expense, including such incentives or increases, is recognized on a straight-line basis over the term of the lease.

Debt Issuance Costs

Debt issuance costs incurred to obtain debt financing are deferred and are amortized over the term of the debt using the effective interest method. The costs are recorded as a reduction to the carrying value of the debt and the amortization expense is included in interest expense in the statements of operations.

Revenue Recognition

Revenue is recognized in accordance with revenue recognition accounting guidance, which utilizes five basic steps to determine whether revenue can be recognized and to what extent: (i) identify the contract with a customer; (ii) identify the performance obligation; (iii) determine the transaction price; (iv) allocate the transaction price; and (v) determine the recognition period.

Performance Obligations. We evaluate deliverables on a contract by contract basis to determine whether each deliverable represents a good or service that is distinct or has the same pattern of transfer as other deliverables. A deliverable is considered distinct if the customer can benefit from the good or service independently of other goods/services either in the contract or that can be obtained elsewhere, without regard to contract exclusivity, and the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contact. If the deliverable is not considered distinct, we combine such deliverables and account for them as a single performance obligation. We allocate the consideration to each deliverable at the inception of the arrangement based on the transaction price.

Our performance obligations may include the following:

•

License Arrangements. The performance obligations under our collaboration and license agreements generally include exclusive or nonexclusive licenses to one or more products generated using our technologies. Licenses for multiple antibodies within a single contract are generally combined as they have substantially the same pattern of transfer to the customer. Historically, our licenses have held no value to the customer, as the antibodies were in the discovery phase and required our expertise for further development. Accordingly, licenses are not considered distinct.

•

Research and Development Services. The performance obligations under our collaboration and license agreements generally include research and development services we perform on behalf of or with our collaborators. As discussed within license arrangements above, our licenses have historically held no value without the research and development services we provide. As we generally only provide research and development services for internally generated antibodies that require a license to be utilized by a third party, our research and development services are not considered distinct.


•	Steering Committee Meetings. The performance obligations under our collaboration and license agreements may also include our participation in a steering committees, which allows us to direct the progression of our discovery programs. As these steering committees would not occur or benefit the customer without the use of our licenses, these are not considered distinct.

We recognize consideration allocated to a performance obligation as the performance obligation is satisfied, and the determination as to whether consideration is recognized over time or at a point in time is made upon contract inception. For our collaboration agreements, this is generally over the period in which research and development services have been performed.

Transaction Price. Our collaboration and license agreements generally include both fixed and variable consideration. Fixed payments, such as those for upfront fees are included in the transaction price at contract value, while variable consideration such as reimbursement for research and development services, milestone and royalty payments are estimated and then evaluated for constraints upon inception of the contract and evaluated on a quarterly basis thereafter. Research and development services are updated for actual invoices. Given the nature of our agreements, milestones are estimated using the most likely amount and are evaluated on a quarterly basis. Upon commercialization, royalty payments are recognized in the period incurred.

Research and Development

Research and development costs primarily include third-party clinical and preclinical research and development services such as manufacturing, laboratory and related supplies, salaries and personnel-related costs, in-licensing fees, outside services, and an allocation of information technology, fringe benefits, and facility overhead costs.

Costs associated with research and development activities are expensed as incurred. We account for nonrefundable advance payments for goods and services that will be used in future research and development activities as expense when the service has been performed or when the goods have been received. Upfront and milestone payments incurred under our in-licensing agreements are expensed as acquired in-process research and development in the period in which they are incurred, provided that the technology or method has no alternative future use.

Australian Research and Development Tax Incentive

We are eligible under the Australian Research and Development Tax Incentive Program, or the Tax Incentive, to obtain a cash refund from the Australian Taxation Office for eligible research and development expenditures. However, we must have revenue of less than AUD $20.0 million during the reimbursable period and cannot be controlled by income tax exempt entities. The Tax Incentive is recognized as a reduction to research and development expense when there is reasonable assurance that the Tax Incentive will be received, the relevant expenditure has been incurred, and the amount can be reliably measured. The Tax Incentive is denominated in Australian dollars and, therefore, the related receivable is remeasured into U.S. dollars as of each reporting date.

Stock-Based Compensation

We recognize stock-based compensation expense using a fair-value-based method for costs related to all share-based payments, including stock options. Stock-based compensation cost for stock options granted to our employees and directors is measured at the grant date based on the fair-value of the award which is estimated using the Black-Scholes option-pricing model, and is recognized as expense over the requisite service period on a straight-line basis. We recognize forfeitures in the period in which forfeiture occur and record stock-based compensation expense as though all awards are expected to vest.

No tax benefits for stock-based compensation have been recognized in the statements of changes in stockholders’ equity or cash flows. We have not recognized, and do not expect to recognize in the near future, any tax benefit related to stock-based compensation cost as a result of our full valuation allowance on net deferred tax assets and net operating loss carryforwards.

Warrants for Shares of Preferred Stock

In January 2017, upon completion of our IPO, all warrants were reclassified to additional paid-in capital. Prior to this, we accounted for warrants for shares of preferred stock with conversion features that provide for reductions in the warrant price as derivative liabilities in the accompanying balance sheets at their fair value on the date of issuance. The derivative liabilities were revalued at each balance sheet date, with changes in the fair value between reporting periods recorded as other income or expense in the consolidated statement of operations.

Income Taxes

We account for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to be recovered or settled. Realization of deferred tax assets is dependent upon future taxable income. A valuation allowance is recognized if it is more likely than not that some portion or all of a deferred tax asset will not be realized based on the weight of available evidence, including expected future earnings.

We recognize an uncertain tax position in our consolidated financial statements when we conclude that a tax position is more likely than not to be sustained upon examination based solely on technical merits. Only after a tax position passes the first step of recognition will measurement be required. Under the measurement step, the tax benefit is measured as the largest amount of benefit that is more likely than not to be realized upon effective settlement. This is determined on a cumulative probability basis. The full impact of any change in recognition or measurement is reflected in the period in which such change occurs. We have elected to accrue any interest or penalties related to income taxes as part of our income tax expense.

Functional Currency of Foreign Operations

Our Australian subsidiary operates in a U.S. dollar functional currency environment. Assets and liabilities of our foreign subsidiary that are not denominated in the functional currency are remeasured into U.S. dollars at foreign currency exchange rates in effect at the balance sheet date except for nonmonetary assets and capital accounts, which are remeasured at historical foreign currency exchange rates in effect at the date of transaction. Expenses are generally remeasured at monthly foreign currency exchange rates which approximate average rates in effect during each period. Net realized and unrealized gains and losses from foreign currency transactions and remeasurement are reported in other income (expense), net, in the consolidated statements of operations.

Comprehensive Income (Loss)

Comprehensive income (loss) represents all changes in stockholders’ equity except those resulting from distributions to stockholders. Our unrealized gain and losses on available for sale investments represent the only component of other comprehensive income (loss) that is excluded from the reported net income (loss).

Net Loss Per Common Share

Basic net loss per common share is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common equivalent shares outstanding for the period, as well as any dilutive effect from outstanding stock options and warrants using the treasury stock method. For each period presented, there is no difference in the number of shares used to calculate basic and diluted net loss per share.

The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because to do so would be anti-dilutive (in common stock equivalent shares):



	Year Ended December 31,
(in thousands)	2018	2017	2016
Convertible preferred stock	—	—	11,521
Options to purchase common stock	2,451	2,478	1,969
Warrants to purchase preferred stock	—	—	295
Warrants to purchase common stock	—	161	117
Total	2,451	2,639	13,902

Accounting Pronouncements Recently Adopted

In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606), which outlines a single comprehensive model for entities to use in accounting for revenue from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. This standard is based on the principle that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This standard also requires additional disclosure about the nature, amount, timing and uncertainty of assets recognized from costs incurred to fulfill a contract and became effective for our annual reporting period beginning January 1, 2018, including interim periods within that reporting period. Entities have the option of using either a full retrospective or a modified retrospective approach for the adoption of the new standard. We assessed all potential impacts of the standard, and the most significant impacts relate to our accounting for variable consideration including revenues related to contingent “milestone” based payments and our disclosures required under the new standard as it relates to our two ongoing collaboration agreements, TESARO and Celgene. Application of the new standard requires that variable consideration be recognized to the extent that it is probable that a significant reversal in the amount of revenue will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Accordingly, we may be required to recognize milestone payments earlier in the period in which we determine a significant reversal will not occur, rather than when the milestone is achieved. However, we reviewed the TESARO and Celgene agreements and determined that given the nature of potential milestones owed to us under these agreements, and the inherent risk involved in developing drugs, these potential milestones were not recognizable as of the standard adoption date. Additionally, while we currently disaggregate our revenue disclosures by collaborative agreement, additional discussion surrounding significant estimates made by management was required in our disclosure and included in Note 4 below. We adopted this standard using the modified retrospective approach for our annual reporting period beginning January 1, 2018, and did not record any adjustments upon adoption of this standard.

In January 2016, the FASB issued ASU 2016-01, Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, which intends to enhance the reporting model for financial instruments by providing users of financial instruments with more decision-useful information. The standard also addresses certain aspects of the recognition, measurement, presentation, and disclosure of financial instruments and requires additional disclosure about the nature, amount, timing and uncertainty of assets recognized from costs incurred to fulfill a contract and became effective for our annual reporting period beginning January 1, 2018, including interim periods within that reporting period; early adoption is permitted. We adopted this standard as of January 1, 2018 and there was no material impact on our consolidated financial statements. We did not record any adjustments upon adoption of this standard and have consistently applied our accounting policies to all periods presented in the consolidated financial statements.

In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718), which provides further guidance as to what constitutes a modification to the terms of shared based compensation, in order to create consistency in practice amongst all entities. ASU 2017-09 became effective for annual reporting periods beginning after December 15, 2017, including interim periods thereafter; early adoption is permitted, including adoption in an interim period. We adopted this standard as of January 1, 2018, and the impact was not material on our consolidated financial statements. We did not record any adjustments upon adoption of this standard.

Recent Accounting Pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which requires that lessees recognize a right-of-use, or “ROU”, asset and a related lease liability on the balance sheet for all leases with a term longer than 12 months. Topic 842 was subsequently amended by ASU 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU 2018-10, Codification Improvements to Topic 842, Leases; and ASU 2018-11, Targeted Improvements. ASU 2016-02 becomes effective for our annual reporting period beginning January 1, 2019, including interim periods thereafter; early adoption is permitted. A modified retrospective transition approach is required, applying the new standard to all leases existing at the date of initial application. An entity may choose to use either (i) its effective date or (ii) the beginning of the earliest comparative period presented in the financial statements as its date of initial application. We expect to adopt the new standard on January 1, 2019 and use the effective date as our date of initial application. The new standard provides a number of optional practical expedients in transition. We expect to elect the ‘package of practical expedients’, which permits us not to reassess under the new standard our prior conclusions about lease identification, lease classification and initial direct costs. Adoption of the new standard will result in the recording of operating lease ROU assets and lease liabilities of approximately $2.1 million and $2.3 million as of January 1, 2019, respectively related to our real estate leases. Adoption of this new standard will not have a material impact on our consolidated statements of operations or cash flows.

Balance Sheet Accounts and Supplemental Disclosures

12 Months Ended

Dec. 31, 2018

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Accounts and Supplemental Disclosures

Property and Equipment

Property and equipment consist of the following:



(in thousands)	December 31, 2018			December 31, 2017
Laboratory equipment	$	4,287		$	3,687
Office furniture and equipment	780			605
Leasehold improvements	575			351
Property and equipment, gross	5,642			4,643
Less: accumulated depreciation and amortization	(4,197		)	(3,978		)
Total property and equipment, net	$	1,445		$	665

Accrued Expenses

Accrued expenses consist of the following:



(in thousands)	December 31, 2018		December 31, 2017
Accrued compensation and related expenses	$	2,421	$	1,588
Accrued research and contract manufacturing expenses	5,577		2,961
Other	763		326
Total accrued expenses	$	8,761	$	4,875

Collaborative Research and Development Agreements

12 Months Ended

Dec. 31, 2018

Revenue Recognition [Abstract]

Collaborative Research and Development Agreements

TESARO Collaboration

In March 2014, we entered into a Collaboration and Exclusive License Agreement, or the TESARO Agreement, with TESARO, Inc. and TESARO Development, Inc., or collectively, TESARO, an oncology-focused biopharmaceutical company. Under the terms of the agreement, we agreed to perform certain discovery and early preclinical development of therapeutic antibodies with the goal of generating immunotherapy antibodies for subsequent preclinical, clinical, regulatory and commercial development to be performed by TESARO. Under the terms of the agreement, TESARO paid an upfront license fee of $17.0 million in March 2014 and agreed to provide funding to us for research and development services related to antibody discovery programs for three specific targets. In November 2014, we and TESARO entered into Amendment No. 1 to the Agreement to add an antibody discovery program against an undisclosed fourth target for an upfront license fee of $2.0 million.

For each development program, we are eligible to receive milestone payments of up to $18.0 million if certain preclinical and clinical trial events are achieved by TESARO, up to an additional $90.0 million if certain U.S. and European regulatory submissions and approvals in multiple indications are achieved, and up to an additional $165.0 million upon the achievement of specified levels of annual worldwide net sales. We will also be eligible to receive tiered single-digit royalties related to worldwide net sales of products developed under the collaboration. Unless earlier terminated by either party upon specified circumstances, the agreement will terminate, with respect to each specific developed product, upon the latter of the 12th anniversary of the first commercial sale of the product or the expiration of the last to expire of any patent. Prior to the adoption of ASC Topic 606, we determined that the upfront license fees and research funding under the agreement, as amended, should be accounted for as a single unit of accounting and that the upfront license fees should be deferred and recognized as revenue over the same period that the research and development services are performed. In December 2015, we determined that the research and development services would be extended through December 31, 2016. As a result, the period over which the unrecognized license fees and milestones were recognized was extended through December 31, 2016, and have been recognized in full.

We assessed this arrangement in accordance with ASC Topic 606 and concluded that the contract counterparty, TESARO, is a customer. We identified the following material promises under the TESARO Agreement: (1) the licenses under certain patent rights relating to six discovery programs (four targets) and transfer of certain development and regulatory information, (2) R&D services and (3) Joint Steering Committee meetings. We considered the research and discovery capabilities of TESARO for these specific programs, TESARO’s inability to sub-license, and the fact that the discovery and optimization of these antibodies is proprietary and could not, at the time of the contract inception, be provided by other vendors, to conclude that the license does not have stand-alone functionality and is therefore not distinct. Additionally, we determined that the steering committee participation would not have been provided without the R&D services and license agreement. Based on these assessments, we identified all services to be interrelated, and therefore concluded that the promises should be combined into a single performance obligation at the inception of the arrangement.

As of December 31, 2018, the transaction price includes the upfront payment, research reimbursement revenue, and milestones earned to date, which are allocated in their entirety to the single performance obligation. We earned and recognized one clinical milestone for $5.0 million during the year ended December 31, 2018. No other future clinical or regulatory milestones have been included in the transaction price, as all milestone amounts were subject to the revenue constraint. As part of the constraint evaluation, we considered numerous factors including the fact that the receipt of milestones is outside of our control and contingent upon success in future clinical trials, an outcome that is difficult to predict, and the licensees’ efforts. Any consideration related to sales-based milestones, including royalties, will be recognized when the related sales occur as they were determined to relate predominantly to the IP license granted to TESARO and therefore have also been excluded from the transaction price. We will re-evaluate the variable transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur.

Milestones recognized through December 31, 2018 under the TESARO Agreement are as follows:



	Anti-PD-1 (TSR042)		Anti-TIM-3 (TSR022)		Anti-LAG-3 (TSR033)
Milestone Event	Amount	Quarter Recognized	Amount	Quarter Recognized	Amount	Quarter Recognized
Initiated in vivo toxicology studies using good laboratory practices (GLPs)	$1.0M	Q2'15	$1.0M	Q4'15	$1.0M	Q3'16
IND clearance from the FDA	$4.0M	Q1'16	$4.0M	Q2'16	$4.0M	Q2'17
Phase 2 clinical trial initiation	$3.0M	Q2'17	$3.0M	Q4'17	—	—
Phase 3 clinical trial initiation	$5.0M	Q3'18	—	—	—	—

Milestones achieved during the discovery period were recognized as revenue pro-rata through December 31, 2016. Milestones achieved during fiscal 2017 were recognized as revenue in the period earned, while milestones after December 31, 2017 are recognized upon determination that a significant reversal of revenue would not be probable. Cash is generally received within 30 days of milestone achievement.

We recognized $5.0 million in revenue under this agreement during the year ended December 31, 2018 related to one milestone and recognized $10.0 million during the year ended December 31, 2017 related to three milestones. We recognized aggregated revenue under this agreement of $15.2 million during the year ended December 31, 2016, which includes $9.3 million related to milestones earned, $3.2 million in funding for research and development services and $2.6 million for the amortization of the upfront fee.

Antibody Generation Agreement with Celgene Corporation

In December 2011, we entered into a license and collaboration agreement with Celgene, or the Celgene Agreement, to develop therapeutic antibodies against multiple targets. We granted Celgene the option to obtain worldwide commercial rights to antibodies generated against each of the targets under the agreement, which option was triggered on a target-by-target basis by our delivery of antibodies meeting certain pre-specified parameters pertaining to each target under the agreement. The agreement provided for an upfront payment of $6.0 million from Celgene, which we received in 2011 and recognized through 2014, milestone payments of up to $53.0 million per target, low single-digit royalties on net sales of antibodies against each target, and reimbursement of specified research and development costs.

We assessed this arrangement in accordance with ASC Topic 606 and concluded that the contract counterparty, Celgene, is a customer. We identified the following material promises under the Celgene Agreement: (1) the licenses under certain patent rights relating to four targets and transfer of certain development and regulatory information, (2) R&D services, (3) a written report documenting findings and (4) Steering Committee meetings. We considered the research and discovery capabilities of Celgene, Celgene’s inability to sub-license the four targets, and the fact that the discovery and optimization of these antibodies is proprietary and could not, at the time of the contract inception, be provided by other vendors, to conclude that the license does not have stand-alone functionality and is therefore not distinct. Additionally, we determined that the report of findings and steering committee participation would not have been provided without the R&D services and license agreement. Based on these assessments, we identified all services to be interrelated, and therefore concluded that the promises should be combined into a single performance obligation at the inception the arrangement.

As of December 31, 2018, the transaction price includes the upfront payment, success fees, expense reimbursement, and milestones earned to date, which are allocated in their entirety to the single performance obligation. None of the future clinical or regulatory milestones have been included in the transaction price, as all milestone amounts were subject to the revenue constraint. As part of the constraint evaluation, we considered numerous factors, including the fact that the receipt of milestones is outside of our control and contingent upon success in future clinical trials and the licensees’ efforts. Any consideration related to sales-based milestones, including royalties, will be recognized when the related sales occur as they were determined to relate predominantly to the IP license granted to Celgene and therefore have also been excluded from the transaction price. We will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur.

Milestones achieved through December 31, 2018 under the Celgene Agreement are as follows:



	Anti-PD-1 (CC-90006)
Milestone Event	Amount	Quarter Recognized
Completion of first in vivo toxicology studies using GLPs	$0.5M	Q2'16
Phase 1 clinical trial initiation	$1.0M	Q4'16

Milestones achieved during fiscal 2016 were recognized as revenue in the period earned, while revenue from future contingent milestone payments will be recognized when it is more likely than not that the revenue will not be reversed in future periods. Cash is generally received within 30 days of milestone achievement.

There was no revenue recognized under this agreement during the years ended December 31, 2018 and 2017. Revenue recognized under this agreement aggregated $1.5 million during the year ended December 31, 2016 related to two milestones earned.

Notes Payable	12 Months Ended
Notes Payable	Dec. 31, 2018
Debt Disclosure [Abstract]
Notes Payable	Notes Payable On December 24, 2014, we entered into a Loan and Security Agreement, as amended from time to time, the Loan Agreement, with a bank and a financial institution whereby we may borrow up to $15.0 million in three separate draws of $5.0 million each. The Term A Loans, for an aggregate of $5.0 million, were drawn on December 24, 2014 with a fixed interest rate of 6.97%. In connection with the issuance of the Term A Loans, we issued detachable, fully vested warrants to purchase an aggregate of 41,208 shares of Series C Preferred Stock at an exercise price of $4.55 per share to the lenders. The grant-date fair value of the warrants of $0.1 million was recorded as a liability, with a reduction to the carrying value of the Term A Loans, and which is recognized as additional interest expense over the remaining term of the Loans. The initial fair value of the warrants was determined using the Black-Scholes option pricing model with the following assumptions: a stock price volatility of 70.2%, an expected life equal to the contractual term of the warrants of ten years and a risk-free interest rate of 1.97%. In January 2016, the Loan Agreement was amended to combine Term B Loans and Term C Loans for a total of $10.0 million available for draw through December 31, 2016 and delay the beginning of our Term A Loans’ principal repayments from February 1, 2016 until February 1, 2017. The Term B Loans and Term C Loans became available for draw on July 1, 2016. In December 2016, we further amended the Loan Agreement to (i) allow for the Term B Loans and Term C Loans to be drawn on December 30, 2016, (ii) delay principal repayments of all Term Loans until February 1, 2018 and (iii) amend the interest rate for each Term Loan. The Term B Loans and the Term C Loans were drawn on December 30, 2016, and Term A, B and C Loans are now collectively referred to as the Term Loans. Principal repayments began in February 2018, and as of December 31, 2018, there are 13 monthly principal and interest payments remaining on the Term Loans, with final maturity in January 2020. The Term Loans bear interest equal to the greater of 3-month U.S. LIBOR plus 6.37% or 7.3%. The interest rate was 8.93% as of December 31, 2018. In connection with the issuance of the Term B & C Loans, we issued detachable, fully vested warrants to purchase an aggregate of 82,416 shares of Series C Preferred Stock at an exercise price of $4.55 per share to the lenders. The grant-date fair value of the warrants of $0.9 million was recorded as a liability, with a reduction to the carrying value of the Term B & C Loans, and which is recognized as additional interest expense over the remaining term of the Loans. The initial fair value of the warrants was determined using the Black-Scholes option pricing model with the following assumptions: a stock price volatility of 79.2%, an expected life equal to the contractual term of the warrants of ten years and a risk-free interest rate of 2.45%. As discussed in Note 7 below, all of the outstanding warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock in connection with the IPO and were accounted for as equity from the conversion date forward. All warrants related to Term Loans were exercised during the year ended December 31, 2017. The costs incurred to issue the Term Loans were deferred and are included in the discount to the carrying value of the Term Loans in the accompanying balance sheet. The Term Loans also include a final payment fee of $0.8 million due at the earlier of prepayment or the maturity date of the Term Loans. The deferred costs and the final payment fee are being amortized to interest expense over the expected term of the Term A Loans using the effective interest method. As of December 31, 2018, the carrying amount of the Term Loans was $8.2 million, which includes amortized final payment fees of $0.1 million and of which $7.6 million is classified as current liabilities as of December 31, 2018. The effective interest rate on the Term Loans at December 31, 2018 was 13.32%. As of December 31, 2018, future principal maturities of the Term Loans were $7.5 million, and $0.6 million in 2019 and 2020, respectively. The Term Loans are secured by a first priority interest in most of our assets, excluding intellectual property. As of December 31, 2018, we were in compliance with the covenants contained in the Loan Agreement.

Fair Value Measurements and Available for Sale Investments

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements and Available for Sale Investments

Fair Value Measurements

Our financial instruments consist principally of cash, cash equivalents, restricted cash, short-term and long-term investments, receivables, accounts payable, notes payable and, through January 31, 2017, preferred stock warrant liabilities. Certain of our financial assets and liabilities have been recorded at fair value in the consolidated balance sheet in accordance with the accounting standards for fair value measurements.

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants on the measurement date. Accounting guidance also establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value:

Level 1 - Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

Level 2 - Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level 3 - Unobservable inputs that are supported by little or no market activities, therefore requiring an entity to develop its own assumptions.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following table summarizes our assets and liabilities that require fair value measurements on a recurring basis and their respective input levels based on the fair value hierarchy:



	Fair Value Measurements at End of Period Using:
(in thousands)	Fair Value		Quoted Market Prices for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
At December 31, 2018
Money market funds⁽¹⁾	$	87,213	$	87,213	$	—	$	—
Mutual funds⁽¹⁾	7,967		7,967		—		—
U.S. treasury securities⁽²⁾	164,245		164,245		—		—
Certificates of deposit⁽²⁾	4,784		—		4,784		—
Agency securities⁽¹⁾⁽²⁾	81,296		—		81,296		—
Commercial and corporate obligations⁽¹⁾⁽²⁾	153,983		—		153,983		—
At December 31, 2017
Money market funds⁽¹⁾	$	41,318	$	41,318	$	—	$	—
Mutual funds⁽¹⁾	28,817		28,817		—		—
U.S. treasury securities⁽²⁾	79,397		79,397		—		—
Agency securities ⁽²⁾	59,948		—		59,948		—
Commercial and corporate obligations⁽²⁾	111,660		—		111,660		—


⁽¹⁾	Included in cash and cash equivalents, and restricted cash in the accompanying consolidated balance sheets.


⁽²⁾	Included in short-term or long-term investments in the accompanying consolidated balance sheets depending on the respective maturity date.

The following methods and assumptions were used to estimate the fair value of our financial instruments for which it is practicable to estimate that value:

Marketable Securities. For fair values determined by Level 1 inputs, which utilize quoted prices in active markets for identical assets, the level of judgment required to estimate fair value is relatively low. For fair values determined by Level 2 inputs, which utilize quoted prices in less active markets for similar assets, the level of judgment required to estimate fair value is also considered relatively low.

Warrant Liabilities. Our preferred stock warrants were accounted for as derivative liabilities and measured at fair value on a recurring basis through January 31, 2017 as they contained features that were either not afforded equity classification or embodied risks that were not clearly and closely related to host contracts. We estimated the fair value of these derivatives utilizing the Black-Scholes option-pricing model, which required Level 3 inputs.

As discussed in Note 7 below, all of the outstanding warrants to purchase shares of preferred stock automatically converted into warrants to purchase shares of common stock in connection with the IPO and are accounted for as equity from the conversion date forward. Prior to the conversion, we estimated the fair value of convertible preferred stock warrants at the time of issuance and upon subsequent remeasurement using the Black-Scholes option-pricing model at each reporting date.

The following weighted-average assumptions were utilized in estimating the value of the liabilities for Series C preferred stock warrants using the Black-Scholes option-pricing model as of January 31, 2017, the conversion date:



	January 31, 2017
Fair value of preferred stock	$	16.95
Exercise price	$	4.55
Risk-free interest rate	1.4		%
Volatility	88.8		%
Dividend Yield	—		%
Contractual term (in years)	3.8
Weighted-average measurement date fair value per share	$	13.71

The following table summarizes the activity in liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3 Inputs):



	Year Ended December 31,
(in thousands)	2017
Preferred Stock Warrant Liabilities:
Beginning balance	$	(3,241	)
Net gains (losses) included in other expense	(1,366		)
Reclassification of warrant liabilities to equity	4,607
Ending balance	$	—

Fair Value of Other Financial Instruments

The fair value of our other financial instruments estimated as of December 31, 2018 and December 31, 2017 are presented below:



	December 31, 2018				December 31, 2017
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Notes payable	$	8,199	$	8,806	$	14,428	$	15,650

The following methods and assumptions were used to estimate the fair value of our notes payable:

Notes Payable—We use the income approach to value the aforementioned debt instrument. We use a present value calculation to discount principal and interest payments and the final maturity payment on these liabilities using a discounted cash flow model based on observable inputs. We discount these debt instruments based on what the current market rates would offer us as of the reporting date. Based on the assumptions used to value these liabilities at fair value, these debt instruments are categorized as Level 2 in the fair value hierarchy.

The carrying amounts of certain of our financial instruments, including cash and cash equivalents, Australian tax incentive receivable, accounts payable, and accrued expenses approximate fair value due to their short-term nature.

Available for Sale Investments

We invest our excess cash in agency securities, debt instruments of financial institutions and corporations, commercial obligations, and U.S. Treasury securities, which we classify as available-for-sale investments. These investments are carried at fair value and are included in the tables above. The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents, short-term and long-term investments as of December 31, 2018 are as follows:



(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Total Fair Value
Agency securities⁽¹⁾	$	81,371	$	62	$	(137	)	$	81,296
Certificates of deposit⁽²⁾	4,784		—		—			4,784
Commercial and corporate obligations⁽³⁾	154,070		62		(149		)	153,983
US Treasury securities⁽⁴⁾	164,251		96		(102		)	164,245
Total available-for-sale investments	$	404,476	$	220	$	(388	)	$	404,308


⁽¹⁾	Of our outstanding agency securities, $67.4 million have maturity dates of less than one year and $13.9 million have a maturity date of between one to two years as of December 31, 2018.


⁽²⁾	All of our outstanding certificates of deposit have a maturity date of between one to two years as of December 31, 2018.


⁽³⁾	Of our outstanding commercial and corporate obligations, $126.8 million have maturity dates of less than one year and $27.2 million have a maturity date of between one to two years as of December 31, 2018.


⁽⁴⁾	Of our outstanding U.S. Treasury securities $137.0 million have maturity dates of less than one year and $27.3 million have a maturity date of between one to two years as of December 31, 2018.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Stockholders' Equity

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Stockholders' Equity

Stockholders’ Equity

Common and Preferred Stock

On January 31, 2017, upon completion of our IPO, we amended our Certificate of Incorporation to increase the number of authorized shares of common stock to 500,000,000 with a par value of $0.001 and decrease the number of authorized shares of preferred stock to 10,000,000 with a par value of $0.001 per share.

Common Stock

Of the 500,000,000 shares of common stock authorized, 26,921,822 shares were issued and outstanding as of December 31, 2018. Common stock reserved for future issuance upon the exercise, issuance or conversion of the respective equity instruments at December 31, 2018 are as follows:



Issued and Outstanding:
Stock options	2,152,455
Shares Reserved For:
2017 Equity Incentive Plan	2,021,019
2017 Employee Stock Purchase Plan	455,193
Total	4,628,667

Warrant Exercises

During the year ended December 31, 2018, 16,770 shares of common stock were issued as a result of warrant exercises. During the year ended December 31, 2017, warrants for the purchase of 477,908 shares of common stock were exercised, of which 359,999 were exercised by a net exercise method. As a result, we issued 398,837 shares of common stock. As of December 31, 2018, all warrants have been exercised.

Repurchase of Common Stock

Certain stock option grants under our 2006 Equity Incentive Plan, or the 2006 Plan, were subject to an early exercise provision. Shares of common stock obtained upon early exercise of unvested options are subject to repurchase by us at the applicable original issue price. During the year ended December 31, 2016, we repurchased 1,457 shares of common stock. No shares were repurchased during the years ended December 31, 2018 or 2017.

Equity Incentive Plans

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Equity Incentive Plans

2017 Equity Incentive Plan

On January 12, 2017, our board of directors and stockholders approved and adopted the 2017 Equity Incentive Plan, or the 2017 Plan. The 2017 Plan became effective upon the execution and delivery of the underwriting agreement for our initial public offering on January 26, 2017, and replaced our existing 2006 Equity Incentive Plan, or the 2006 Plan. Under the 2017 Plan we may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other awards to individuals who are then our employees, officers, directors or consultants. In addition, the number of shares of stock available for issuance under the 2017 Plan will be automatically increased each January 1, beginning on January 1, 2018, by 4% of the aggregate number of outstanding shares of our common stock as of the immediately preceding December 31 or such lesser number as determined by our board of directors. The 2017 Plan automatically increased by 951,656 shares as of January 1, 2018.

Employee Stock Purchase Plan

On January 12, 2017, our board of directors and stockholders approved and adopted the 2017 Employee Stock Purchase Plan or the ESPP. The ESPP became effective upon the execution and delivery of the underwriting agreement for our initial public offering on January 26, 2017. In addition, the number shares of stock available for issuance under the ESPP will be automatically increased each January 1, beginning on January 1, 2018, by 1% of the aggregate number of outstanding shares of our common stock as of the immediately preceding December 31 or such lesser number as determined by our board of directors. The ESPP automatically increased by 237,913 shares as of January 1, 2018.

Stock Options

Stock options granted to employees and non-employees generally vest over a four-year period while stock options granted to directors vest over a one-year period. Each have a maximum term of ten years from the date of grant, subject to earlier cancellation prior to vesting upon cessation of service to us. A summary of the activity related to stock option awards during the year ended December 31, 2018 is as follows:



	Shares Subject to Options		Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2018	2,425,903		$	12.03
Granted	368,607		$	98.19
Exercises	(583,660	)	$	4.92
Forfeitures and cancellations	(58,395	)	$	55.13
Outstanding at December 31, 2018	2,152,455		$	27.55	7.07	$	90,143
Exercisable at December 31, 2018	1,265,626		$	13.01	6.30	$	65,718

Total cash received from the exercise of stock options was approximately $2.9 million during the year ended December 31, 2018.

Stock-Based Compensation Expense

The estimated fair values of stock option awards granted to employees were determined on the date of grant using the Black-Scholes option valuation model with the following weighted average assumptions:



	Year Ended December 31,
	2018			2017			2016
Risk-free interest rate	2.7		%	2.0		%	1.4		%
Expected volatility	67.7		%	64.3		%	70.5		%
Expected dividend yield	—		%	—		%	—		%
Expected term (in years)	6.25			6.25			6.25
Weighted average grant date fair value per share	$	61.41		$	14.82		$	4.35

We determine the appropriate risk free interest rate, expected term for employee stock based awards, contractual term for non-employee stock-based awards, and volatility assumptions. The weighted-average expected option term for employee and director stock based awards reflects the application of the simplified method, which defines the life as the average of the contractual term of the options and the weighted average vesting period for all option tranches. The weighted average expected term for non-employee stock-based awards is the remaining contractual life of the award. Estimated volatility incorporates historical volatility of similar entities whose share prices are publicly available. The risk free interest rate is based upon U.S. Treasury securities with remaining terms similar to the expected or contractual term of the stock-based payment awards. The assumed dividend yield is based on our expectation of not paying dividends in the foreseeable future.

There were 368,607, 1,099,806 and 330,622 stock options granted during the years ended December 31, 2018, 2017 and 2016, respectively.

Total non-cash stock-based compensation expense for all stock awards that was recognized in the consolidated statements of operations and comprehensive loss is as follows:



	Year Ended December 31,
(in thousands)	2018		2017		2016
Research and development	$	3,371	$	1,347	$	420
General and administrative	6,590		3,031		740
Total	$	9,961	$	4,378	$	1,160

At December 31, 2018, there was $25.6 million of unrecognized compensation cost related to unvested stock option awards, which is expected to be recognized over a remaining weighted average vesting period of 2.36 years.

Australia Research and Development Tax Incentive

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Australia Research and Development Tax Incentive

Our Australian subsidiary, which conducts core research and development activities on our behalf, is eligible to receive a 43.5% refundable tax incentive for qualified research and development activities during fiscal 2018 and fiscal 2017, and 45.0% during fiscal 2016. For the years ended December 31, 2018, 2017 and 2016, $0.1 million, $1.5 million and $7.2 million, respectively, were recorded as a reduction to research and development expenses in the consolidated statements of operations and comprehensive loss. As of December 31, 2018 our tax incentive receivable from the Australian government was $0.2 million. We received approximately $1.5 million and $4.6 million in cash during the years ended December 31, 2018 and 2017, respectively, related to the tax incentive.

Income Taxes

The components of loss before income tax benefit consist of the following:



	Year Ended December 31,
(in thousands)	2018			2017			2016
U.S.	$	(61,193	)	$	(27,494	)	$	(632	)
Foreign	(655		)	(2,576		)	(3,627		)
Consolidated net loss before income taxes	$	(61,848	)	$	(30,070	)	$	(4,259	)

Significant components of our deferred tax assets and liabilities are as follows:



	December 31,
(in thousands)	2018			2017
Deferred Tax Assets:
Net operating loss carryforwards	$	35,499		$	17,408
Research and development credits	9,190			4,773
Other, net	2,948			1,686
Total deferred tax assets	47,637			23,867
Deferred Tax Liabilities:
Fixed assets	(49		)	(57		)
Total deferred tax liabilities	(49		)	(57		)
Net deferred tax assets	47,588			23,810
Less: valuation allowance	(47,588		)	(23,810		)
Deferred tax assets, net of valuation allowance	$	—		$	—

We have recorded a full valuation allowance against our net deferred tax assets due to the uncertainty surrounding the realization of such assets. Management has determined it more likely than not that the deferred tax assets are not realizable due to our historical loss position.

At December 31, 2018, we had federal and state net operating loss carryforwards, or NOLs, of $145.3 million and $59.1 million, respectively. The federal and state NOLs will both begin to expire in 2028, unless previously utilized. The federal NOLs include $85.2 million of net operating losses generated in 2018. Federal net operating losses generated in 2018 carryforward indefinitely and may generally be used to offset up to 80% of future taxable income in the year it is utilized. At December 31, 2018 we had federal and California research tax credit carryforwards of $6.1 million and $5.9 million, respectively. The federal research tax credit carryforwards will begin to expire in 2026 and the California state credits carryforward indefinitely. We also have foreign tax losses of $2.7 million, which will carry forward indefinitely, subject to a continuity of ownership test.

The above NOLs and the research tax credit carryforwards may be subject to an annual limitation under Section 382 and 383 of the Internal Revenue Code of 1986, as amended, or the Code, and similar state provisions if we experience one or more ownership changes which would limit the amount of NOL and tax credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change as defined by Section 382 and 383, results from transactions increasing ownership of certain stockholders or public groups in the stock of the corporation by more than 50 percentage points over a three-year period. In September 2015, we completed a Section 382 analysis through December 31, 2014 and determined that there was an ownership change in 2007 that may limit the utilization of approximately $5.3 million and $5.4 million in federal and state NOLs, respectively, and $0.2 million in both federal and state research tax credits. We extended the analysis period through December 31, 2018, noting an ownership change in 2017 that may limit the utilization of Federal and State NOLs. Our use of federal NOLs could be limited further by the provisions of Section 382 of the Code depending upon the timing and amount of additional equity securities that we have issued or will issue. State NOLs may be similarly limited. If limited, the related asset would be removed from the deferred tax asset schedule with a corresponding reduction in the valuation allowance. Due to the existence of the valuation allowance, limitations created by ownership changes will not impact our effective tax rate.

The following is a reconciliation of the expected statutory federal income tax provision to our actual income tax provision:



	Year Ended December 31,
(in thousands)	2018			2017			2016
Expected income tax benefit at federal statutory tax rate	$	(12,988	)	$	(10,223	)	$	(1,448	)
State income taxes, net of federal benefit	(166		)	(787		)	(174		)
Permanent items	17			13			12
Equity compensation⁽¹⁾	(6,693		)	(739		)	163
Change in fair value of preferred stock warrant liabilities	—			464			257
Research and development expenditure	63			679			789
Refundable AMT credit	(139		)	—			—
Return to provision adjustment	60			11			1,957
Rate differential	155			297			52
Federal rate adjustment - tax reform	—			7,595			—
Research credits	(4,393		)	(1,554		)	(814		)
Change in the valuation allowance	23,892			4,244			(794		)
Income tax benefit	$	(192	)	$	—		$	—

⁽¹⁾ Includes non-deductible stock-based compensation and, beginning in 2017, excess tax benefits from stock-based compensation. During fiscal 2018, our tax provision includes $4.9 million of excess tax benefits associated with the exercise of non-qualified stock options and $2.2 million associated with the disqualifying dispositions of incentive stock options. During fiscal 2017, our tax provision includes $0.4 million of excess tax benefits associated with the exercise of non-qualified stock options and $0.7 million associated with the disqualifying dispositions of incentive stock options.

The Tax Cuts and Jobs Act, or the 2017 Act, was enacted on December 22, 2017, and includes a number of changes to existing U.S. tax laws that impact us, most notably a reduction of the U.S. corporate income tax rate from 35% to 21% for tax years beginning after December 31, 2017. The 2017 Act also provides for a one-time transition tax on certain foreign earnings and the acceleration of depreciation for certain assets placed in service after September 27, 2017 as well as prospective changes beginning in 2018, including additional limitations on: executive compensation; the deductibility of interest; the usage of NOLs against taxable income; the capitalization of research and development expenditures. While the 2017 Act provides for a territorial tax system, beginning in 2018, it includes two new U.S. tax base erosion provision, the global intangible low-taxed income, or GILTI provisions and the base-erosion and anti-abuse tax, or BEAT, provisions.

We completed our analysis of the 2017 Act income tax effects and remeasured our deferred tax assets and liabilities to reflect the reduction in the U.S. corporate income tax rate from 35% to 21% percent, resulting in a $7.6 million increase in tax expense for the year ended December 31, 2017 and a corresponding $7.6 million decrease in net deferred tax assets for the year ended December 31, 2017. The impact was fully offset by a valuation allowance.

On December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed, including computations, in reasonable detail to complete the accounting for certain income tax effects of the 2017 Act. We applied the guidance in SAB 118 when accounting for all of the enactment-date income tax effects of the Act under ASC 740, Income Taxes, related to the remeasurement of deferred tax assets and liabilities. As of December 31, 2018, we have completed our accounting for all of the enactment-date income tax effects of the Act and no adjustments were made to the provisional amounts recorded at December 31, 2017.

We recognize a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Income tax positions must meet a more likely than not recognition at the effective date to be recognized. At December 31, 2018 and 2017, we had no unrecognized tax benefits that if recognized and realized, would affect the effective tax rate due to the valuation allowance against deferred tax assets. The following table summarizes the activity related to our unrecognized tax benefits:



	Year Ended December 31,
(in thousands)	2018		2017
Balance at the beginning of the year	$	591	$	409
Increase related to prior year tax positions	9		—
Increase related to current year tax positions	1,212		182
Balance at the end of the year	$	1,812	$	591

If recognized, these amounts would not affect our effective tax rate, since they would be offset by an equal corresponding adjustment in the deferred tax asset valuation allowance. We do not anticipate there will be a significant change in unrecognized tax benefits within the next 12 months.

Our policy is to recognize interest and penalties related to income tax matters in the provision for income taxes. At December 31, 2018, 2017 and 2016, there were no interest or penalties on uncertain tax benefits.

We file income tax returns in the United States, California and Australia. Due to our losses incurred, we are essentially subject to income tax examination by tax authorities from inception to date.

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit Plan We have a defined-contribution 401(k) plan for our employees. Employees are eligible to participate in the plan beginning on the first day of the month following date of hire. Under the terms of the plan, employees may make voluntary contributions as a percentage of compensation and we have the option to make a discretionary match as determined by the board of directors, within prescribed limits. There were no employer contributions to the plan during the years ended December 31, 2018, 2017 and 2016.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Operating Leases

In May 2018, we entered into a three-year non-cancellable sub-lease agreement for an additional 18,000 square feet of office space, which we determined to be an operating lease. This lease has three renewal options, each for one year, which we currently do not anticipate exercising. We also continue to lease our headquarters under a non-cancellable operating lease for which we early exercised our option to renew for an additional five-year period in fiscal 2015. Both leases expire in 2021.

Rent expense was $0.7 million, $0.5 million and $0.5 million during the years ended December 31, 2018, 2017 and 2016, respectively. At December 31, 2018, deferred rent aggregated $0.2 million, which is included in both current and noncurrent liabilities in the accompanying consolidated balance sheets. At December 31, 2018, the future minimum annual obligations under non-cancellable operating lease commitments are as follows:



Years Ending December 31, (in thousands)
2019	$	937
2020	969
2021	726
2022	—
2023	—
Thereafter	—
Total minimum payments required	$	2,632

License Agreements

We have certain obligations under licensing agreements with third parties that are contingent upon achieving various development, regulatory and commercial milestones. Pursuant to these license agreements, we are required to make milestone payments if certain development, regulatory and commercial sales milestones are achieved. Also, pursuant to the terms of each of these license agreements, when and if commercial sales of a product commence, we will pay royalties to our licensors on net sales of the respective products.

Certain of the licensing agreements require guaranteed minimum annual payments. Terms of the licensing agreements generally range from the remaining life of the patent up to 19 years and, in some cases, may be subject to earlier termination by either party upon specified circumstances.

Total expense incurred under all collaborative licensing agreements for upfront, milestone and royalty payments were $0.3 million, $0.5 million and $0.3 million during the years ended December 31, 2018, 2017 and 2016, respectively. Total cash paid under these agreements was $0.2 million, $0.6 million, and $0.2 million during the years ended December 31, 2018, 2017, and 2016, respectively.

Future minimum annual obligations under all such license agreements will be $0.2 million in aggregate during 2019, and thereafter. These obligations are payable through ten years from the first commercial sale, if any, or expiration of the last patent to expire, the dates of which are not determinable at this time.

Other Commitments and Contingencies

We have entered into agreements with certain vendors for the provision of goods and services, which includes manufacturing services with contract manufacturing organizations and development services with contract research organizations. These agreements may include certain provisions for purchase obligations and termination obligations that could require payments for the cancellation of committed purchase obligations or for early termination of the agreements. The amount of the cancellation or termination payments vary and are based on the timing of the cancellation or termination and the specific terms of the agreement.

Guarantees and Indemnifications

We enter into standard indemnification arrangements in the ordinary course of business. Pursuant to certain of these arrangements, we indemnify, hold harmless, and agree to reimburse the indemnified parties for losses suffered or incurred by the indemnified party for third-party claims in connection with our breach of the agreement, our negligence or willful misconduct in connection with the agreement, or any trade secret, copyright, patent or other intellectual property infringement claim with respect to our technology. The term of these indemnification arrangements is generally perpetual. The maximum potential amount of future payments we could be required to make under these agreements is not determinable because it involves claims that may be made against us in the future, but have not yet been made.

We indemnify our officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving in such capacity, as permitted under Delaware law, in accordance with our certificate of incorporation and bylaws, and pursuant to agreements providing for indemnification entered into with our officers and directors. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity.

The maximum amount of potential future indemnification of directors and officers is unlimited; however, we currently hold director and officer liability insurance. This insurance allows the transfer of risk associated with our exposure and may enable us to recover a portion of any future amounts paid.

We believe that the fair value of these indemnification obligations is minimal. Accordingly, we have not recognized any liabilities relating to these obligations for any period presented.

Letter of Credit

At December 31, 2018 and 2017, we were contingently liable for a standby letter of credit issued by a commercial bank for $60,000 for security on our lease. A restricted cash account with these amounts was held as cash collateral for the letter of credit.

Litigation

We are, from time to time, involved in legal proceedings, regulatory actions, claims and litigation arising in the ordinary course of business. Currently, we are not involved in any legal proceeding that we expect to have a material effect on our business, financial condition, results of operations and cash flows.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

Australia Research and Development Tax Incentive

Income Taxes

The components of loss before income tax benefit consist of the following:



	Year Ended December 31,
(in thousands)	2018			2017			2016
U.S.	$	(61,193	)	$	(27,494	)	$	(632	)
Foreign	(655		)	(2,576		)	(3,627		)
Consolidated net loss before income taxes	$	(61,848	)	$	(30,070	)	$	(4,259	)

Significant components of our deferred tax assets and liabilities are as follows:



	December 31,
(in thousands)	2018			2017
Deferred Tax Assets:
Net operating loss carryforwards	$	35,499		$	17,408
Research and development credits	9,190			4,773
Other, net	2,948			1,686
Total deferred tax assets	47,637			23,867
Deferred Tax Liabilities:
Fixed assets	(49		)	(57		)
Total deferred tax liabilities	(49		)	(57		)
Net deferred tax assets	47,588			23,810
Less: valuation allowance	(47,588		)	(23,810		)
Deferred tax assets, net of valuation allowance	$	—		$	—

The following is a reconciliation of the expected statutory federal income tax provision to our actual income tax provision:



	Year Ended December 31,
(in thousands)	2018			2017			2016
Expected income tax benefit at federal statutory tax rate	$	(12,988	)	$	(10,223	)	$	(1,448	)
State income taxes, net of federal benefit	(166		)	(787		)	(174		)
Permanent items	17			13			12
Equity compensation⁽¹⁾	(6,693		)	(739		)	163
Change in fair value of preferred stock warrant liabilities	—			464			257
Research and development expenditure	63			679			789
Refundable AMT credit	(139		)	—			—
Return to provision adjustment	60			11			1,957
Rate differential	155			297			52
Federal rate adjustment - tax reform	—			7,595			—
Research credits	(4,393		)	(1,554		)	(814		)
Change in the valuation allowance	23,892			4,244			(794		)
Income tax benefit	$	(192	)	$	—		$	—



	Year Ended December 31,
(in thousands)	2018		2017
Balance at the beginning of the year	$	591	$	409
Increase related to prior year tax positions	9		—
Increase related to current year tax positions	1,212		182
Balance at the end of the year	$	1,812	$	591

We file income tax returns in the United States, California and Australia. Due to our losses incurred, we are essentially subject to income tax examination by tax authorities from inception to date.

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

The following is a summary of our quarterly results for the years ended December 31, 2018 and 2017 (in thousands, except for per share data):



	Quarter												Year Ended December 31, 2018
2018	First			Second			Third			Fourth			Year Ended December 31, 2018
Operating loss	$	(15,757	)	$	(14,415	)	$	(16,887	)	$	(19,663	)	$	(66,722	)
Net loss	$	(15,086	)	$	(13,618	)	$	(15,958	)	$	(16,994	)	$	(61,656	)
Per common share:
Loss per share, basic	$	(0.63	)	$	(0.57	)	$	(0.66	)	$	(0.64	)	$	(2.50	)
Loss per share, diluted	$	(0.63	)	$	(0.57	)	$	(0.66	)	$	(0.64	)	$	(2.50	)

	Quarter												Year Ended December 31, 2017
2017	First			Second			Third			Fourth			Year Ended December 31, 2017
Operating loss	$	(9,988	)	$	(2,555	)	$	(9,087	)	$	(7,151	)	$	(28,781	)
Net loss	$	(11,435	)	$	(2,684	)	$	(9,090	)	$	(6,861	)	$	(30,070	)
Per common share:
Loss per share, basic	$	(0.75	)	$	(0.13	)	$	(0.45	)	$	(0.30	)	$	(1.52	)
Loss per share, diluted	$	(0.75	)	$	(0.13	)	$	(0.45	)	$	(0.30	)	$	(1.52	)

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

Basis of Consolidation

Use of Estimates

Cash and Cash Equivalents

Short Term and Long Term Investments

Concentration of Credit Risk

Property and Equipment

Long Lived Assets

Leases, Deferred Rent and Operating Lease Incentives

Debt Issuance Costs

Revenue Recognition

Our performance obligations may include the following:

•


•	Steering Committee Meetings. The performance obligations under our collaboration and license agreements may also include our participation in a steering committees, which allows us to direct the progression of our discovery programs. As these steering committees would not occur or benefit the customer without the use of our licenses, these are not considered distinct.

Research and Development

Share-Based Compensation

Stock-Based Compensation

Warrants for Shares of Preferred Stock

Income Taxes

Foreign Currency of Foreign Operations

Functional Currency of Foreign Operations

Comprehensive Loss

Comprehensive Income (Loss)

Net Loss Per Common Share

Accounting Pronouncements Recently Adopted and Recent Accounting Pronouncements

Accounting Pronouncements Recently Adopted

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Schedule of Outstanding Potentially Dilutive Securities Excluded in the Calculation of Diluted Net Loss Per Share



	Year Ended December 31,
(in thousands)	2018	2017	2016
Convertible preferred stock	—	—	11,521
Options to purchase common stock	2,451	2,478	1,969
Warrants to purchase preferred stock	—	—	295
Warrants to purchase common stock	—	161	117
Total	2,451	2,639	13,902

Balance Sheet Accounts and Supplemental Disclosures (Tables)

12 Months Ended

Dec. 31, 2018

Balance Sheet Related Disclosures [Abstract]

Property and Equipment

Property and equipment consist of the following:



(in thousands)	December 31, 2018			December 31, 2017
Laboratory equipment	$	4,287		$	3,687
Office furniture and equipment	780			605
Leasehold improvements	575			351
Property and equipment, gross	5,642			4,643
Less: accumulated depreciation and amortization	(4,197		)	(3,978		)
Total property and equipment, net	$	1,445		$	665

Schedule of Accrued Expenses

Accrued expenses consist of the following:



(in thousands)	December 31, 2018		December 31, 2017
Accrued compensation and related expenses	$	2,421	$	1,588
Accrued research and contract manufacturing expenses	5,577		2,961
Other	763		326
Total accrued expenses	$	8,761	$	4,875

Collaborative Research and Development Agreements (Tables)

12 Months Ended

Dec. 31, 2018

Revenue Recognition [Abstract]

Schedule of Milestones Achieved

Milestones recognized through December 31, 2018 under the TESARO Agreement are as follows:



	Anti-PD-1 (TSR042)		Anti-TIM-3 (TSR022)		Anti-LAG-3 (TSR033)
Milestone Event	Amount	Quarter Recognized	Amount	Quarter Recognized	Amount	Quarter Recognized
Initiated in vivo toxicology studies using good laboratory practices (GLPs)	$1.0M	Q2'15	$1.0M	Q4'15	$1.0M	Q3'16
IND clearance from the FDA	$4.0M	Q1'16	$4.0M	Q2'16	$4.0M	Q2'17
Phase 2 clinical trial initiation	$3.0M	Q2'17	$3.0M	Q4'17	—	—
Phase 3 clinical trial initiation	$5.0M	Q3'18	—	—	—	—

Milestones achieved through December 31, 2018 under the Celgene Agreement are as follows:



	Anti-PD-1 (CC-90006)
Milestone Event	Amount	Quarter Recognized
Completion of first in vivo toxicology studies using GLPs	$0.5M	Q2'16
Phase 1 clinical trial initiation	$1.0M	Q4'16

Fair Value Measurements and Available for Sale Investments (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities that Require Fair Value Measurements on a Recurring Basis

The following table summarizes our assets and liabilities that require fair value measurements on a recurring basis and their respective input levels based on the fair value hierarchy:



	Fair Value Measurements at End of Period Using:
(in thousands)	Fair Value		Quoted Market Prices for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
At December 31, 2018
Money market funds⁽¹⁾	$	87,213	$	87,213	$	—	$	—
Mutual funds⁽¹⁾	7,967		7,967		—		—
U.S. treasury securities⁽²⁾	164,245		164,245		—		—
Certificates of deposit⁽²⁾	4,784		—		4,784		—
Agency securities⁽¹⁾⁽²⁾	81,296		—		81,296		—
Commercial and corporate obligations⁽¹⁾⁽²⁾	153,983		—		153,983		—
At December 31, 2017
Money market funds⁽¹⁾	$	41,318	$	41,318	$	—	$	—
Mutual funds⁽¹⁾	28,817		28,817		—		—
U.S. treasury securities⁽²⁾	79,397		79,397		—		—
Agency securities ⁽²⁾	59,948		—		59,948		—
Commercial and corporate obligations⁽²⁾	111,660		—		111,660		—


⁽¹⁾	Included in cash and cash equivalents, and restricted cash in the accompanying consolidated balance sheets.


⁽²⁾	Included in short-term or long-term investments in the accompanying consolidated balance sheets depending on the respective maturity date.

Schedule of Weighted-average Assumptions for Liabilities for Series C Preferred Stock Warrants



	January 31, 2017
Fair value of preferred stock	$	16.95
Exercise price	$	4.55
Risk-free interest rate	1.4		%
Volatility	88.8		%
Dividend Yield	—		%
Contractual term (in years)	3.8
Weighted-average measurement date fair value per share	$	13.71

Summary of Activity in Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs

The following table summarizes the activity in liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3 Inputs):



	Year Ended December 31,
(in thousands)	2017
Preferred Stock Warrant Liabilities:
Beginning balance	$	(3,241	)
Net gains (losses) included in other expense	(1,366		)
Reclassification of warrant liabilities to equity	4,607
Ending balance	$	—

Fair Value of Other Financial Instruments

The fair value of our other financial instruments estimated as of December 31, 2018 and December 31, 2017 are presented below:



	December 31, 2018				December 31, 2017
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Notes payable	$	8,199	$	8,806	$	14,428	$	15,650

Available-for-sale Investments

The aggregate market value, cost basis, and gross unrealized gains and losses of available-for-sale investments by security type, classified in cash equivalents, short-term and long-term investments as of December 31, 2018 are as follows:



(in thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Total Fair Value
Agency securities⁽¹⁾	$	81,371	$	62	$	(137	)	$	81,296
Certificates of deposit⁽²⁾	4,784		—		—			4,784
Commercial and corporate obligations⁽³⁾	154,070		62		(149		)	153,983
US Treasury securities⁽⁴⁾	164,251		96		(102		)	164,245
Total available-for-sale investments	$	404,476	$	220	$	(388	)	$	404,308


⁽¹⁾	Of our outstanding agency securities, $67.4 million have maturity dates of less than one year and $13.9 million have a maturity date of between one to two years as of December 31, 2018.


⁽²⁾	All of our outstanding certificates of deposit have a maturity date of between one to two years as of December 31, 2018.


⁽³⁾	Of our outstanding commercial and corporate obligations, $126.8 million have maturity dates of less than one year and $27.2 million have a maturity date of between one to two years as of December 31, 2018.


⁽⁴⁾	Of our outstanding U.S. Treasury securities $137.0 million have maturity dates of less than one year and $27.3 million have a maturity date of between one to two years as of December 31, 2018.

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Schedule of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance upon the exercise, issuance or conversion of the respective equity instruments at December 31, 2018 are as follows:



Issued and Outstanding:
Stock options	2,152,455
Shares Reserved For:
2017 Equity Incentive Plan	2,021,019
2017 Employee Stock Purchase Plan	455,193
Total	4,628,667

Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Activity Related to Stock Option Awards

A summary of the activity related to stock option awards during the year ended December 31, 2018 is as follows:



	Shares Subject to Options		Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2018	2,425,903		$	12.03
Granted	368,607		$	98.19
Exercises	(583,660	)	$	4.92
Forfeitures and cancellations	(58,395	)	$	55.13
Outstanding at December 31, 2018	2,152,455		$	27.55	7.07	$	90,143
Exercisable at December 31, 2018	1,265,626		$	13.01	6.30	$	65,718

Summary of Weighted Average Assumptions in Stock Option Valuations



	Year Ended December 31,
	2018			2017			2016
Risk-free interest rate	2.7		%	2.0		%	1.4		%
Expected volatility	67.7		%	64.3		%	70.5		%
Expected dividend yield	—		%	—		%	—		%
Expected term (in years)	6.25			6.25			6.25
Weighted average grant date fair value per share	$	61.41		$	14.82		$	4.35

Summary of Non-cash Stock-based Compensation Expense

Total non-cash stock-based compensation expense for all stock awards that was recognized in the consolidated statements of operations and comprehensive loss is as follows:



	Year Ended December 31,
(in thousands)	2018		2017		2016
Research and development	$	3,371	$	1,347	$	420
General and administrative	6,590		3,031		740
Total	$	9,961	$	4,378	$	1,160

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Schedule of future minimum annual obligations under operating leases

At December 31, 2018, the future minimum annual obligations under non-cancellable operating lease commitments are as follows:



Years Ending December 31, (in thousands)
2019	$	937
2020	969
2021	726
2022	—
2023	—
Thereafter	—
Total minimum payments required	$	2,632

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Components of income/(loss) before income tax provision (benefit)

The components of loss before income tax benefit consist of the following:



	Year Ended December 31,
(in thousands)	2018			2017			2016
U.S.	$	(61,193	)	$	(27,494	)	$	(632	)
Foreign	(655		)	(2,576		)	(3,627		)
Consolidated net loss before income taxes	$	(61,848	)	$	(30,070	)	$	(4,259	)

Schedule of components of deferred tax assets and liabilities

Significant components of our deferred tax assets and liabilities are as follows:



	December 31,
(in thousands)	2018			2017
Deferred Tax Assets:
Net operating loss carryforwards	$	35,499		$	17,408
Research and development credits	9,190			4,773
Other, net	2,948			1,686
Total deferred tax assets	47,637			23,867
Deferred Tax Liabilities:
Fixed assets	(49		)	(57		)
Total deferred tax liabilities	(49		)	(57		)
Net deferred tax assets	47,588			23,810
Less: valuation allowance	(47,588		)	(23,810		)
Deferred tax assets, net of valuation allowance	$	—		$	—

Reconciliation of expected statutory federal income tax provision and actual income tax provision

The following is a reconciliation of the expected statutory federal income tax provision to our actual income tax provision:



	Year Ended December 31,
(in thousands)	2018			2017			2016
Expected income tax benefit at federal statutory tax rate	$	(12,988	)	$	(10,223	)	$	(1,448	)
State income taxes, net of federal benefit	(166		)	(787		)	(174		)
Permanent items	17			13			12
Equity compensation⁽¹⁾	(6,693		)	(739		)	163
Change in fair value of preferred stock warrant liabilities	—			464			257
Research and development expenditure	63			679			789
Refundable AMT credit	(139		)	—			—
Return to provision adjustment	60			11			1,957
Rate differential	155			297			52
Federal rate adjustment - tax reform	—			7,595			—
Research credits	(4,393		)	(1,554		)	(814		)
Change in the valuation allowance	23,892			4,244			(794		)
Income tax benefit	$	(192	)	$	—		$	—

Schedule of activity related to unrecognized tax benefits

The following table summarizes the activity related to our unrecognized tax benefits:



	Year Ended December 31,
(in thousands)	2018		2017
Balance at the beginning of the year	$	591	$	409
Increase related to prior year tax positions	9		—
Increase related to current year tax positions	1,212		182
Balance at the end of the year	$	1,812	$	591

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Summary of quarterly results

The following is a summary of our quarterly results for the years ended December 31, 2018 and 2017 (in thousands, except for per share data):



	Quarter												Year Ended December 31, 2018
2018	First			Second			Third			Fourth			Year Ended December 31, 2018
Operating loss	$	(15,757	)	$	(14,415	)	$	(16,887	)	$	(19,663	)	$	(66,722	)
Net loss	$	(15,086	)	$	(13,618	)	$	(15,958	)	$	(16,994	)	$	(61,656	)
Per common share:
Loss per share, basic	$	(0.63	)	$	(0.57	)	$	(0.66	)	$	(0.64	)	$	(2.50	)
Loss per share, diluted	$	(0.63	)	$	(0.57	)	$	(0.66	)	$	(0.64	)	$	(2.50	)

	Quarter												Year Ended December 31, 2017
2017	First			Second			Third			Fourth			Year Ended December 31, 2017
Operating loss	$	(9,988	)	$	(2,555	)	$	(9,087	)	$	(7,151	)	$	(28,781	)
Net loss	$	(11,435	)	$	(2,684	)	$	(9,090	)	$	(6,861	)	$	(30,070	)
Per common share:
Loss per share, basic	$	(0.75	)	$	(0.13	)	$	(0.45	)	$	(0.30	)	$	(1.52	)
Loss per share, diluted	$	(0.75	)	$	(0.13	)	$	(0.45	)	$	(0.30	)	$	(1.52	)

Description of the Business (Details) $ / shares in Units, $ in Thousands						12 Months Ended
	Sep. 28, 2018 USD ($) $ / shares shares	Nov. 14, 2017 USD ($) $ / shares shares	Oct. 17, 2017 USD ($) $ / shares shares	Jan. 31, 2017 USD ($) $ / shares shares	Jan. 13, 2017	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($)	Jan. 30, 2017 shares
Class of Warrant or Right [Line Items]
Common shares issued (in shares)	2,530,000		3,000,000
Share price (in dollars per share) \| $ / shares	$ 94.46		$ 68.50
Reverse stock split, conversion ratio					0.1429
Proceeds, net of underwriters' fees \| $	$ 227,500		$ 194,700			$ 227,476	$ 292,537	$ 0
Convertible preferred stock
Class of Warrant or Right [Line Items]
Number of shares called by warrants (in shares)									377,195
Common Stock
Class of Warrant or Right [Line Items]
Common shares issued (in shares)						2,530,000	9,021,000
Convertible preferred stock, converted to common stock (in shares)							11,521,000
Number of shares called by warrants (in shares)				377,195
IPO
Class of Warrant or Right [Line Items]
Proceeds from public offerings, net of underwriters' fees \| $				$ 80,200
IPO \| Common Stock
Class of Warrant or Right [Line Items]
Common shares issued (in shares)				5,750,000
Share price (in dollars per share) \| $ / shares				$ 15.00
Convertible preferred stock, converted to common stock (in shares)				11,520,698
Underwriters' option
Class of Warrant or Right [Line Items]
Common shares issued (in shares)	330,000	271,380		750,000
Share price (in dollars per share) \| $ / shares		$ 68.5
Proceeds, net of underwriters' fees \| $		$ 17,600

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) bank segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 AUD ($)
Accounting Policies [Abstract]
Number of reportable segments \| segment	1
Restricted Cash	$ 60,000	$ 60,000
Number of banks utilized for diversification of funds (in banks) \| bank	3
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Long-lived asset impairment charges	$ 0	$ 0	$ 0
Australian research and development tax incentive, threshold for reimbursable period					$ 20,000,000
Forecast \| ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
ROU asset				$ 2,100,000
Lease liability				$ 2,300,000
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, useful life	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, useful life	7 years

Summary of Significant Accounting Policies - Summary of Potentially Dilutive Securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities excluded from computation of net loss per share (in shares)	2,451	2,639	13,902
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities excluded from computation of net loss per share (in shares)	0	0	11,521
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities excluded from computation of net loss per share (in shares)	2,451	2,478	1,969
Warrants \| Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities excluded from computation of net loss per share (in shares)	0	0	295
Warrants \| Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive securities excluded from computation of net loss per share (in shares)	0	161	117

Balance Sheet Accounts and Supplemental Disclosures - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 5,642	$ 4,643
Less: accumulated depreciation and amortization	(4,197)	(3,978)
Total property and equipment, net	1,445	665
Laboratory equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,287	3,687
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	780	605
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 575	$ 351

Balance Sheet Accounts and Supplemental Disclosures - Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Accrued compensation and related expenses	$ 2,421	$ 1,588
Accrued research and contract manufacturing expenses	5,577	2,961
Other	763	326
Total accrued expenses	$ 8,761	$ 4,875

Collaborative Research and Development Agreements (Details)	1 Months Ended		3 Months Ended									12 Months Ended
	Nov. 30, 2014 USD ($) target	Mar. 31, 2014 USD ($) target	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2018 USD ($) milestone	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) milestone	Dec. 31, 2011 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone method, revenue recognized												$ 5,000,000	$ 10,000,000	$ 16,684,000
TESARO
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone method, revenue recognized												$ 5,000,000	10,000,000	15,200,000
TESARO \| Collaborative Research and Development Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront license fee received	$ 2,000,000	$ 17,000,000
Number of outstanding research and development targets \| target	4	3
Milestone payments, contingent upon preclinical and clinical trial events (up to)	$ 18,000,000
Milestone payments, contingent upon certain U.S. and European regulatory submissions and approvals (up to)	90,000,000
Milestone payments, contingent upon achievement of specified levels of worldwide sales (up to)	$ 165,000,000
Agreement term following first commercial sale or expiration of the last to expire patent (in years)	12 years
Milestone method, revenue recognized														2,600,000
Number of milestones achieved during period \| milestone												1
Revenue recognized, funding for research and development services														3,200,000
Amortization of upfront fee														9,300,000
TESARO \| In Vivo Toxicology Studies Using GLPs \| AnaptysBio Generated Anti-PD-1 Antagonist Antibody (TSR-042)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones achieved during period, amount											$ 1,000,000
TESARO \| In Vivo Toxicology Studies Using GLPs \| AnaptysBio Generated Anti-TIM3 Antagonist Antibody (TSR-022)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones achieved during period, amount										$ 1,000,000
TESARO \| In Vivo Toxicology Studies Using GLPs \| AnaptysBio Generated Anti-LAG3 Antagonist Antibody (TSR-033)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones achieved during period, amount							$ 1,000,000
TESARO \| IND clearance from the FDA \| AnaptysBio Generated Anti-PD-1 Antagonist Antibody (TSR-042)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones achieved during period, amount									$ 4,000,000
TESARO \| IND clearance from the FDA \| AnaptysBio Generated Anti-TIM3 Antagonist Antibody (TSR-022)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones achieved during period, amount								$ 4,000,000
TESARO \| IND clearance from the FDA \| AnaptysBio Generated Anti-LAG3 Antagonist Antibody (TSR-033)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones achieved during period, amount					$ 4,000,000
TESARO \| Phase 2 clinical trial initiation \| AnaptysBio Generated Anti-PD-1 Antagonist Antibody (TSR-042)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones achieved during period, amount					$ 3,000,000
TESARO \| Phase 2 clinical trial initiation \| AnaptysBio Generated Anti-TIM3 Antagonist Antibody (TSR-022)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones achieved during period, amount				$ 3,000,000
TESARO \| Phase 3 clinical trial initiation \| AnaptysBio Generated Anti-PD-1 Antagonist Antibody (TSR-042)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones achieved during period, amount			$ 5,000,000
Celgene Corporation \| Collaborative Research and Development Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront license fee received															$ 6,000,000
Milestone method, revenue recognized												$ 0	$ 0	$ 1,500,000
Maximum milestone payments per target															$ 53,000,000
Revenue Recognition, Milestone Method, Milestones Achieved During The Period \| milestone														2
Celgene Corporation \| In Vivo Toxicology Studies Using GLPs \| AnaptysBio Generated Anti-PD-1 (CC-90006)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payment earned								$ 500,000
Celgene Corporation \| Phase 1 clinical trial initiation \| AnaptysBio Generated Anti-PD-1 (CC-90006)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payment earned						$ 1,000,000

Notes Payable (Details)		1 Months Ended
Notes Payable (Details)	Dec. 24, 2014 USD ($) installment $ / shares shares	Jan. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) payment	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Notes payable, current portion			$ 7,574,000	$ 6,875,000
Term A Loan Warrants \| Warrants
Debt Instrument [Line Items]
U.S. treasury securities	$ 100,000
Term A Loan Warrants \| Warrants \| Price volatility percent
Debt Instrument [Line Items]
Measurement Input (as a percent)	0.702
Term A Loan Warrants \| Warrants \| Contractual term
Debt Instrument [Line Items]
Contractual term (in years)	10 years
Term A Loan Warrants \| Warrants \| Risk-free interest rate
Debt Instrument [Line Items]
Measurement Input (as a percent)	0.0197
Term A Loan Warrants \| Series C Preferred Stock
Debt Instrument [Line Items]
Number of shares called by warrants (in shares) \| shares	41,208
Warrant exercise price (in dollars per share) \| $ / shares	$ 4.55
Term B And C Loans Warrants \| Warrants
Debt Instrument [Line Items]
U.S. treasury securities		$ 900,000
Term B And C Loans Warrants \| Warrants \| Price volatility percent
Debt Instrument [Line Items]
Measurement Input (as a percent)		0.792
Term B And C Loans Warrants \| Warrants \| Contractual term
Debt Instrument [Line Items]
Contractual term (in years)		10 years
Term B And C Loans Warrants \| Warrants \| Risk-free interest rate
Debt Instrument [Line Items]
Measurement Input (as a percent)		0.0245
Term B And C Loans Warrants \| Series C Preferred Stock
Debt Instrument [Line Items]
Number of shares called by warrants (in shares) \| shares		82,416
Warrant exercise price (in dollars per share) \| $ / shares		$ 4.55
Notes Payable to Banks
Debt Instrument [Line Items]
Aggregate borrowing capacity	$ 5,000,000
Notes Payable to Banks \| Loan and Security Agreement (LSA)
Debt Instrument [Line Items]
Debt instrument, maximum borrowing capacity	$ 15,000,000
Number of loan installments (in installments) \| installment	3
Final payment fee		$ 800,000
Notes payable			8,200,000
Debt instrument discounts			100,000
Notes payable, current portion			$ 7,600,000
Effective interest rate			13.32%
Long-term Debt, Fiscal Year Maturity [Abstract]
2019			$ 7,500,000
2020			$ 600,000
Notes Payable to Banks \| Term Loans
Debt Instrument [Line Items]
Fixed interest rate		7.30%
Number of principal and interest payments (in payments) \| payment			13
Interest rate at period end			8.93%
Notes Payable to Banks \| Term Loans \| 3-Month LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		6.37%
Notes Payable to Banks \| Term A Loans
Debt Instrument [Line Items]
Aggregate draw on term loan	$ 5,000,000
Fixed interest rate	6.97%
Notes Payable to Banks \| Term B and Term C Loans
Debt Instrument [Line Items]
Aggregate borrowing capacity		$ 10,000,000

Fair Value Measurements and Available for Sale Investments - Fair Value Assumptions (Details) - Derivative Financial Instruments, Liabilities - Fair Value, Measurements, Recurring - Series C Preferred Stock	Jan. 31, 2017 $ / shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of preferred stock (in dollars per share)	$ 16.95
Weighted-average measurement date fair value per share (in dollars per share)	$ 13.71
Exercise price (in dollars per share)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	4.55
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.014
Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.888
Dividend Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.000
Contractual term
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contractual term (in years)	3 years 9 months

Fair Value Measurements and Available for Sale Investments - Liabilities with Significant Unobservable Inputs (Details) - Series C Preferred Stock - Derivative Financial Instruments, Liabilities - Fair Value, Measurements, Recurring $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Preferred Stock Warrant Liabilities:
Beginning balance	$ (3,241)
Net gains (losses) included in other expense	(1,366)
Reclassification of warrant liabilities to equity	4,607
Ending balance	$ 0

Fair Value Measurements and Available for Sale Investments - Fair Value of Other Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable	$ 8,199	$ 14,428
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes payable	$ 8,806	$ 15,650

Fair Value Measurements and Available for Sale Investments - Available-for-sale Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 404,476
Gross Unrealized Gains	220
Gross Unrealized Losses	(388)
Total Fair Value	404,308
Short-term investments	313,486	$ 167,218
Long-term investments	73,128	$ 75,897
Agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	81,371
Gross Unrealized Gains	62
Gross Unrealized Losses	(137)
Total Fair Value	81,296
Short-term investments	67,400
Long-term investments	$ 13,900
Agency securities \| Minimum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity	1 year
Agency securities \| Maximum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity	2 years
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 4,784
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Total Fair Value	$ 4,784
Certificates of deposit \| Minimum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity	1 year
Certificates of deposit \| Maximum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity	2 years
Commercial and corporate obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 154,070
Gross Unrealized Gains	62
Gross Unrealized Losses	(149)
Total Fair Value	153,983
Short-term investments	126,800
Long-term investments	$ 27,200
Commercial and corporate obligations \| Minimum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity	1 year
Commercial and corporate obligations \| Maximum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity	2 years
U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 164,251
Gross Unrealized Gains	96
Gross Unrealized Losses	(102)
Total Fair Value	164,245
Short-term investments	137,000
Long-term investments	$ 27,300
U.S. treasury securities \| Minimum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity	1 year
U.S. treasury securities \| Maximum
Debt Securities, Available-for-sale [Line Items]
Remaining maturity	2 years

Stockholders' Equity - Additional Information (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 31, 2017
Equity [Abstract]
Common stock, shares authorized (in shares)	500,000,000	500,000,000		500,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001		$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000		10,000,000
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001		$ 0.001
Common stock, shares issued (in shares)	26,921,822	23,791,000
Common stock, shares outstanding (in shares)	26,921,822	23,791,000
Class of Stock [Line Items]
Repurchase of shares (in shares)	0	0	1,457
Common Stock
Class of Stock [Line Items]
Warrants exercised, number of shares represented (as shares)	16,770	477,908
Warrants exercised, number of shares represented, cashless exercise (as shares)		359,999
Shares issued as a result of warrants exercised (in shares)		398,837
Repurchase of shares (in shares)			2,000

Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2018	Dec. 31, 2017
Issued and Outstanding:
Stock options (in shares)	2,152,455	2,425,903
Common stock, shares reserved for issuance (in shares)	4,628,667
2017 Equity Incentive Plan
Issued and Outstanding:
Shares reserved for future award grants (in shares)	2,021,019
2017 Employee Stock Purchase Plan
Issued and Outstanding:
Shares reserved for future award grants (in shares)	455,193

Equity Incentive Plans - Narrative (Details) - USD ($) $ in Thousands			12 Months Ended
	Jan. 01, 2018	Jan. 26, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common stock, upon the exercise of stock options			$ 2,869	$ 979	$ 31
Granted (in shares)			368,607	1,099,806	330,622
Unrecognized compensation cost			$ 25,600
Employee and Nonemployee Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)		4 years
Award expiration period (in years)		10 years
Weighted average period remaining for amortization of unrecognized compensation cost (in years)			2 years 4 months 8 days
Options \| Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)		1 year
Award expiration period (in years)		10 years
2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase in number of shares available for issuance		4.00%
Capital shares reserved for future issuance, increase (in shares)	951,656
2017 Employee Stock Purchase Plan \| Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual increase in number of shares available for issuance	1.00%
Capital shares reserved for future issuance, increase (in shares)	237,913

Equity Incentive Plans - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares Subject to Options
Stock options outstanding, beginning balance (in shares)	2,425,903
Granted (in shares)	368,607	1,099,806	330,622
Exercises (in shares)	(583,660)
Forfeitures and cancellations (in shares)	(58,395)
Stock options outstanding, ending balance (in shares)	2,152,455	2,425,903
Stock options exercisable, ending balance (in shares)	1,265,626
Weighted-Average Exercise Price per Share
Stock options outstanding, beginning balance (in dollars per share)	$ 12.03
Granted (in dollars per share)	98.19
Exercises (in dollars per share)	4.92
Forfeitures and cancellations (in dollars per share)	55.13
Stock options outstanding, ending balance (in dollars per share)	27.55	$ 12.03
Stock options exercisable, ending balance (in dollars per share)	$ 13.01
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted average remaining contractual term, options outstanding (in years)	7 years 25 days
Weighted average remaining contractual term, options exercisable (in years)	6 years 3 months 20 days
Aggregate intrinsic value, options outstanding	$ 90,143
Aggregate intrinsic value, options exercisable	$ 65,718

Equity Incentive Plans - Option Fair Value Assumptions (Details) - Options - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.70%	2.00%	1.40%
Expected volatility	67.70%	64.30%	70.50%
Expected dividend yield	0.00%	0.00%	0.00%
Expected term (in years)	6 years 3 months	6 years 3 months	6 years 3 months
Weighted average grant date fair value per share (in dollars per share)	$ 61.41	$ 14.82	$ 4.35

Equity Incentive Plans - Allocation of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 9,961	$ 4,378	$ 1,160
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	3,371	1,347	420
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 6,590	$ 3,031	$ 740

Australia Research and Development Tax Incentive (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax Credit Carryforward [Line Items]
Australian tax incentive receivable	$ 174	$ 1,601
Research and development tax incentive credit received during the period	$ 1,500	$ 4,600
Australian Taxation Office \| Subsidiaries
Tax Credit Carryforward [Line Items]
Refundable tax incentive for qualified research and development activities	43.50%	43.50%	45.00%
Research and development	$ 100	$ 1,500	$ 7,200

Employee Benefit Plan (Details) - USD ($)	12 Months Ended
Employee Benefit Plan (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Employer contributions to the plan	$ 0	$ 0	$ 0

Commitments and Contingencies - Operating Leases (Details) ft² in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	May 31, 2018 ft² renewal_options	Dec. 31, 2015
Operating Leased Assets [Line Items]
Operating leases, rent expense	$ 700	$ 500	$ 500
Deferred rent expense	200
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	937
2020	969
2021	726
2022	0
2023	0
Thereafter	0
Total minimum payments required	$ 2,632
New sub-lease agreement
Operating Leased Assets [Line Items]
Operating lease, term of contract				3 years
Operating lease, rented square feet (in square feet) \| ft²				18
Number of one year renewal options \| renewal_options				3
Original lease agreement
Operating Leased Assets [Line Items]
Operating lease, renewal term					5 years

Commitments and Contingencies - Licensing Agreements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Licensing agreement, remaining life	19 years
License costs	$ 300,000	$ 500,000	$ 300,000
Cash payments under licensing agreements	200,000	600,000	$ 200,000
Future minimum annual cash obligations, next 12 months	200,000
Future minimum annual cash obligations, thereafter	$ 200,000
License agreement, obligation payable period	10 years
Standby Letters of Credit
Finite-Lived Intangible Assets [Line Items]
Letters of credit outstanding	$ 60,000	$ 60,000

Income Taxes - Components of income/(loss) before income tax provision (benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
U.S.	$ (61,193)	$ (27,494)	$ (632)
Foreign	(655)	(2,576)	(3,627)
Loss before income taxes	$ (61,848)	$ (30,070)	$ (4,259)

Income Taxes - Deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets:
Net operating loss carryforwards	$ 35,499	$ 17,408
Research and development credits	9,190	4,773
Other, net	2,948	1,686
Total deferred tax assets	47,637	23,867
Deferred Tax Liabilities:
Fixed assets	(49)	(57)
Total deferred tax liabilities	(49)	(57)
Net deferred tax assets	47,588	23,810
Less: valuation allowance	(47,588)	(23,810)
Deferred tax assets, net of valuation allowance	$ 0	$ 0

Income Taxes - Additional information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Excess tax benefits associated with the exercise of non-qualified stock options	$ 4,900,000	$ 400,000
Disqualifying dispositions of incentive stock options	2,200,000	700,000
Tax act, change in tax rate, decrease in deferred tax asset		7,600,000
Unrecognized tax benefits that if recognized and realized would affect the effective tax rate	0	0	$ 0
Interest or penalties on uncertain tax benefits	0	$ 0	$ 0	$ 0
Federal tax authority
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	145,300,000
Net operating loss carryforward, utilization limitation					$ 5,300,000
Federal tax authority \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research tax credit carryforwards	6,100,000
Tax credit carryforward, utilization limitation					200,000
Federal tax authority \| 2018
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	85,200,000
State tax authority
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	59,100,000
Net operating loss carryforward, utilization limitation					5,400,000
State tax authority \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research tax credit carryforwards	5,900,000
Tax credit carryforward, utilization limitation					$ 200,000
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 2,700,000

Income Taxes - Reconciliation of income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Expected income tax benefit at federal statutory tax rate	$ (12,988)	$ (10,223)	$ (1,448)
State income taxes, net of federal benefit	(166)	(787)	(174)
Permanent items	17	13	12
Equity compensation	(6,693)	(739)	163
Change in fair value of preferred stock warrant liabilities	0	464	257
Research and development expenditure	63	679	789
Refundable AMT credit	(139)	0	0
Return to provision adjustment	60	11	1,957
Rate differential	155	297	52
Federal rate adjustment - tax reform	0	7,595	0
Research credits	(4,393)	(1,554)	(814)
Change in the valuation allowance	23,892	4,244	(794)
Income tax benefit	(192)	0	$ 0
Excess tax benefits associated with the exercise of non-qualified stock options	4,900	400
Disqualifying dispositions of incentive stock options	$ 2,200	$ 700

Income Taxes - Unrecognized tax benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at the beginning of the year	$ 591	$ 409
Increase related to prior year tax positions	9	0
Increase related to current year tax positions	1,212	182
Balance at the end of the year	$ 1,812	$ 591

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Operating income (loss)	$ (19,663)	$ (16,887)	$ (14,415)	$ (15,757)	$ (7,151)	$ (9,087)	$ (2,555)	$ (9,988)	$ (66,722)	$ (28,781)	$ (3,025)
Net income (loss)	$ (16,994)	$ (15,958)	$ (13,618)	$ (15,086)	$ (6,861)	$ (9,090)	$ (2,684)	$ (11,435)	$ (61,656)	$ (30,070)
Per common share:
Loss per share, basic (in dollars per share)	$ (0.64)	$ (0.66)	$ (0.57)	$ (0.63)	$ (0.30)	$ (0.45)	$ (0.13)	$ (0.75)	$ (2.50)	$ (1.52)
Loss per share, diluted (in dollars per share)	$ (0.64)	$ (0.66)	$ (0.57)	$ (0.63)	$ (0.30)	$ (0.45)	$ (0.13)	$ (0.75)	$ (2.50)	$ (1.52)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

Fair Value Measurements and Available for Sale Investments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	$ 404,308
U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	164,245
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	4,784
Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	81,296
Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	153,983
Fair Value, Measurements, Recurring \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	164,245	$ 79,397
Fair Value, Measurements, Recurring \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	4,784
Fair Value, Measurements, Recurring \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	81,296	59,948
Fair Value, Measurements, Recurring \| Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	153,983	111,660
Fair Value, Measurements, Recurring \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	87,213	41,318
Fair Value, Measurements, Recurring \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	7,967	28,817
Fair Value, Measurements, Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	164,245	79,397
Fair Value, Measurements, Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	0
Fair Value, Measurements, Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	0	0
Fair Value, Measurements, Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	87,213	41,318
Fair Value, Measurements, Recurring \| Quoted Market Prices for Identical Assets (Level 1) \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	7,967	28,817
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	4,784
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	81,296	59,948
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	153,983	111,660
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2) \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Commercial and corporate obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Fair Value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3) \| Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	$ 0	$ 0