Akebia Therapeutics (AKBA) 10-Q 8 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	AKBA
Entity Registrant Name	Akebia Therapeutics, Inc.
Entity Central Index Key	1,517,022
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		47,269,153

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 89,599	$ 187,335
Available for sale securities	240,106	73,008
Unbilled receivable	281	33,823
Prepaid expenses and other current assets	3,952	2,155
Total current assets	333,938	296,321
Property and equipment, net	3,364	2,612
Other assets	1,287	1,283
Total assets	338,589	300,216
Current liabilities:
Accounts payable	8,705	2,039
Accrued expenses	21,427	30,261
Short-term deferred revenue	121,031	81,968
Short-term deferred rent	194
Total current liabilities	151,357	114,268
Deferred rent, net of current portion	2,633	2,480
Deferred revenue, net of current portion	84,701	115,321
Other non-current liabilities	23	27
Total liabilities	238,714	232,096
Commitments and contingencies (Note 10)
Stockholders' equity:
Preferred stock $0.00001 par value, 25,000,000 shares authorized; 0 shares issued and outstanding at September 30, 2017 and December 31, 2016
Common stock: $0.00001 par value; 175,000,000 shares authorized; 47,238,001 and 38,615,709 shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	486,386	365,298
Accumulated other comprehensive loss	(181)	(42)
Accumulated deficit	(386,330)	(297,136)
Total stockholders' equity	99,875	68,120
Total liabilities and stockholders' equity	$ 338,589	$ 300,216

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.00001	$ 0.00001
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	175,000,000	175,000,000
Common stock, shares issued	47,238,001	38,615,709
Common stock, shares outstanding	47,238,001	38,615,709

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Collaboration revenue	$ 41,283		$ 90,668
Operating expenses:
Research and development	58,711	$ 31,238	162,511	$ 82,350
General and administrative	6,748	4,944	19,441	16,066
Total operating expenses	65,459	36,182	181,952	98,416
Operating loss	(24,176)	(36,182)	(91,284)	(98,416)
Other income (expense):
Interest income	842	219	1,886	722
Other income	200	(345)	204	(191)
Net loss	$ (23,134)	$ (36,308)	$ (89,194)	$ (97,885)
Net loss per share - basic and diluted	$ (0.49)	$ (0.96)	$ (2.11)	$ (2.61)
Weighted-average number of common shares - basic and diluted	46,938,618	37,897,902	42,202,560	37,528,869
Comprehensive loss:
Net loss	$ (23,134)	$ (36,308)	$ (89,194)	$ (97,885)
Other comprehensive gain/(loss) - unrealized gain/(loss) on securities	73	(44)	(181)	(7)
Total comprehensive loss	$ (23,061)	$ (36,352)	$ (89,375)	$ (97,892)

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Net loss	$ (89,194)	$ (97,885)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	420	172
Amortization of premium/discount on investments	543	399
Loss on disposal of property and equipment		306
Fair value of warrants issued for license	3,413
Changes in operating assets and liabilities:
Unbilled receivable	33,542
Prepaid expenses and other current assets	(1,797)	(1,263)
Other long-term assets	(4)
Accounts payable	6,666	6,196
Accrued expense	(8,834)	8,017
Deferred revenue	8,443	40,000
Deferred rent	347	2,193
Net cash used in operating activities	(39,781)	(37,764)
Investing activities:
Purchase of equipment	(1,172)	(2,614)
Proceeds from the maturities of available for sale securities	97,868	125,151
Purchases of available for sale securities	(265,648)	(132,138)
Net cash used in investing activities	(168,952)	(9,601)
Financing activities:
Proceeds from the issuance of common stock, net of issuance costs	109,541	63,205
Proceeds from the sale of stock under employee stock purchase plan	352	106
Proceeds from the exercise of stock options	1,108	125
Payments on capital lease obligations	(4)	(19)
Net cash provided by financing activities	110,997	63,417
(Decrease) increase in cash and cash equivalents	(97,736)	16,052
Cash and cash equivalents at beginning of the period	187,335	49,778
Cash and cash equivalents at end of the period	89,599	65,830
Non-cash financing activities
Unpaid follow-on offering costs		65
Equity Awards
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation - equity awards	$ 6,674	$ 4,101

Nature of Organization and Oper

Nature of Organization and Operations	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Nature of Organization and Operations	1. Nature of Organization and Operations The Company is a biopharmaceutical company focused on developing and delivering novel therapeutics for patients based on hypoxia-inducible factor, or HIF, biology, and building our pipeline while leveraging our development and commercial expertise in renal disease. HIF is the primary regulator of the production of red blood cells, or RBCs, in the body, as well as other important metabolic functions. Pharmacologic modulation of the HIF pathway may have broad therapeutic applications. The Company’s lead product candidate, vadadustat, is an oral therapy in Phase 3 development, which has the potential to set a new standard of care in the treatment of anemia associated with chronic kidney disease, or CKD. The Company’s management team has extensive experience in developing and commercializing drugs for the treatment of renal and metabolic disorders, as well as a deep understanding of HIF biology. This unique combination of HIF and renal expertise is enabling the Company to advance a pipeline of HIF-based therapies to address serious diseases. The Company’s operations to date have been limited to organizing and staffing the Company, business planning, raising capital, acquiring and developing its technology, identifying potential product candidates and undertaking preclinical and clinical studies. The Company has not generated any product revenue to date and may never generate any product revenue in the future. The Company’s product candidates are subject to long development cycles and the Company may be unsuccessful in its efforts to develop, obtain regulatory approval for or market its product candidates. The Company is subject to a number of risks including possible failure of preclinical testing or clinical trials, reliance on contract manufacturing organizations and contract research organizations, the need to obtain marketing approval for its product candidates, the development of new technological innovations by competitors, the need to successfully commercialize and gain market acceptance of any of the Company’s products that are approved and uncertainty around intellectual property matters. If the Company does not successfully commercialize any of its products, it will be unable to generate product revenue or achieve profitability. The Company believes that its existing cash resources of approximately $329.7 million at September 30, 2017, together with committed funding from its collaboration partners, will be sufficient to allow the Company to fund its current operating plan into the second quarter of 2019, and as a result, through at least twelve months from the filing of the Company’s 2017 third quarter Form 10-Q. There can be no assurance, however, that the current operating plan will be achieved in the time frame anticipated by the Company, or that its cash resources will fund the Company’s operating plan for the period anticipated by the Company or that additional funding will be available on terms acceptable to the Company, or at all. We will require additional capital for the further development of our existing product candidates and will need to raise additional funds sooner to pursue development activities related to additional product candidates. If and until we can generate a sufficient amount of revenue from our products, we expect to finance future cash needs through public or private equity, debt offerings, or strategic transactions.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Akebia Therapeutics Securities Corporation and Akebia Europe Limited. All intercompany balances and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (U.S. GAAP). Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (ASC) and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB). In the quarter ended June 30, 2017, we identified and corrected an immaterial error in the amount of research and development expenses related to our global Phase 3 study of vadadustat. This adjustment also affected the amount of revenue recognized pursuant to our license and collaboration agreements with Otsuka. The adjustments impacted our results of operations in each quarter of 2016 and the first quarter of 2017. We concluded the effect of these adjustments was not material to our consolidated financial statements for any prior period. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard-setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In February 2016, the FASB issued ASU 2016-02, Leases In May 2014, the FASB issued a new revenue recognition standard which amends revenue recognition principles and provides a single, comprehensive set of criteria for revenue recognition within and across all industries. The new standard provides a five-step framework whereby revenue is recognized when promised goods or services are transferred to a customer at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard also requires enhanced disclosures pertaining to revenue recognition in both interim and annual periods. In August 2015, the FASB deferred the effective date of the new revenue standard from January 1, 2017 to January 1, 2018. Early adoption is permitted any time after the original effective date, which for us was January 1, 2017. The Company intends to adopt the new standard on January 1, 2018. The standard allows for adoption using a full retrospective method or a modified retrospective method. The Company’s historical revenue has been derived from its collaboration agreements with Otsuka Pharmaceutical Co. Ltd., or Otsuka. The Company will commence revenue recognition under its collaboration agreement with Mitsubishi Tanabe Pharma Corporation, or MTPC, when it begins to deliver the clinical supply of vadadustat to MTPC which the Company expects to be in the fourth quarter of 2017. These arrangements contain multiple-elements and have been accounted for pursuant to Revenue Recognition Multiple‑Element Arrangements . The new revenue standard provides guidance in assessing what comprises the distinct service being provided to a customer that may have implications to our performance obligations and unit of account identified in our three existing collaborations which could be defined differently under the new guidance. As a result, there could be changes to the timing of revenue recognition upon adoption of the new standard. The Company is currently assessing the impact of the new revenue recognition standard on its collaboration agreements with MTPC and Otsuka and evaluating which method it will adopt. Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment, which is the business of developing and commercializing proprietary therapeutics based on HIF biology. Derivative Financial Instruments The Company accounts for warrants and other derivative financial instruments as either equity or liabilities in accordance with ASC Topic 815, Derivatives and Hedging (ASC 815) based upon the characteristics and provisions of each instrument. Warrants classified as equity are recorded at fair value as of the date of issuance on the Company’s consolidated balance sheets and no further adjustments to their valuation are made. Warrants classified as derivative liabilities and other derivative financial instruments that require separate accounting as liabilities are recorded on the Company’s consolidated balance sheets at their fair value on the date of issuance and will be revalued on each subsequent balance sheet date until such instruments are exercised or expire, with any changes in the fair value between reporting periods recorded as other income or expense. The warrant issued by the Company in connection with the Janssen Pharmaceutica NV Research and License Agreement, the Janssen Agreement, is classified as equity in the Company’s condensed consolidated bal ance sheet. (See Note 7). Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, among others: prepaid and accrued research and development expense, stock-based compensation expense, revenue and income taxes. Cash and Cash Equivalents Cash and cash equivalents consist of all cash on hand, deposits and funds invested in available-for-sale securities with original maturities of three months or less at the time of purchase. At September 30, 2017, the Company’s cash is primarily in money market funds. The Company may maintain balances with its banks in excess of federally insured limits. Investments Management determines the appropriate classification of securities at the time of purchase and reevaluates such designation as of each balance sheet date. Currently, the Company classifies all securities as available-for-sale which are included in current assets as they are intended to fund current operations. The Company carries available-for-sale securities at fair value. The Company conducts periodic reviews to identify and evaluate each investment that has an unrealized loss, in accordance with the meaning of other-than-temporary impairment and its application to certain investments. When assessing whether a decline in the fair value of a security is other-than-temporary, the Company considers the fair market value of the security, the duration of the security’s decline, and prospects for the underlying business. Based on these considerations, the Company did not identify any other-than-temporary unrealized losses at September 30, 2017. Unrealized losses on available-for-sale securities that are determined to be temporary, and not related to credit loss, are recorded in accumulated other comprehensive loss, a component of stockholders’ equity. The amortized cost of debt securities in this category reflects amortization of premiums and accretion of discounts to maturity computed under the effective interest method. The Company includes this amortization in the caption “Interest income” within the consolidated statements of operations and comprehensive loss. The Company also includes in net investment income, realized gains and losses and declines in value determined to be other than temporary. The Company bases the cost of securities sold upon the specific identification method, and includes interest and dividends on securities in interest income. Revenue Recognition To date, the Company has not generated any revenue from the sales of products. For the foreseeable future, the Company expects substantially all of its revenues will be generated from its collaborations with MTPC and Otsuka (see Note 3) and any other collaborations the Company may enter into. Multiple-Element Arrangements The Company recognizes revenue in accordance with ASC Topic 605, Revenue Recognition • Persuasive evidence of an arrangement exists; • Delivery has occurred or services have been rendered; • The seller’s price to the buyer is fixed or determinable; and • Collectability is reasonably assured. Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified in current liabilities. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Revenue recognition from our MTPC collaboration will commence when we begin to deliver the clinical supply of vadadustat to MTPC which the Company expects to begin in the fourth quarter of 2017. Therefore, collaboration revenue in the current period is exclusively from our collaborations agreements with Otsuka. The terms of these arrangements contain multiple deliverables, which include at inception: (i) license, (ii) development services, (iii) rights to future intellectual property and (iv) joint committee services. Non-refundable payments to the Company under these arrangements include: (i) up-front fee, (ii) payments for development services and (iii) payments based on the achievement of certain milestones. Also, under the Otsuka U.S. Agreement, the Company and Otsuka share costs incurred with respect to jointly conducted medical affairs and commercialization and non-promotional activities under the collaboration. Additionally, the Company may receive its share of net sales and bear its share of shared costs from the sale of products containing or comprising vadadustat in the United States through its U.S. collaboration with Otsuka. The Company will recognize revenue related to amounts allocated to the License Unit of Accounting on a proportional performance basis as the underlying services are performed. The Company evaluates multiple‑element arrangements based on the guidance in ASC 605‑25. Pursuant to the guidance in ASC 605‑25, the Company evaluates multiple‑element arrangements to determine (i) the deliverables included in the arrangement and (ii) whether the individual deliverables represent separate units of accounting or whether they must be accounted for as a combined unit of accounting. This evaluation involves subjective determinations and requires the Company to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. Deliverables are considered separate units of accounting provided that: (i) the delivered item(s) has value to the customer on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company’s control. In assessing whether an item has standalone value, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can use the other deliverable(s) for their intended purpose without the receipt of the remaining deliverable(s), whether the value of the deliverable is dependent on the undelivered item and whether there are other vendors that can provide the undelivered item(s). The Company’s collaboration arrangements do not contain a general right of return relative to delivered item(s). Arrangement consideration that is fixed or determinable is allocated among the separate units of accounting using the relative selling price method. The Company determines the selling price for a unit of accounting following the hierarchy of evidence prescribed by ASC 605-25. Accordingly, the Company determines the estimated selling price for units of accounting within each arrangement using vendor‑specific objective evidence (VSOE) of selling price, if available, third‑party evidence (TPE) of selling price if VSOE is not available, or best estimate of selling price (BESP) if neither VSOE nor TPE is available. Determining the BESP for a unit of accounting requires significant judgment. In developing the BESP for a unit of accounting, the Company considers applicable market conditions and relevant entity‑specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. The Company validates the BESP for units of accounting by evaluating whether changes in the key assumptions used to determine the BESP will have a significant effect on the allocation of arrangement consideration between multiple units of accounting. The Company recognizes arrangement consideration allocated to each unit of accounting when all of the revenue recognition criteria in ASC 605 are satisfied for that particular unit of accounting. The Company recognizes as revenue arrangement consideration attributed to licenses that have standalone value from other deliverables to be provided in an arrangement upon delivery. The Company recognizes as revenue arrangement consideration attributed to licenses that do not have standalone value from the other deliverables to be provided in an arrangement over the contractual or estimated performance period associated with the undelivered elements included in the combined unit of accounting, which is typically the term of the Company’s development obligations. If there is no discernible pattern of performance and/or objectively measurable performance measures do not exist, then the Company recognizes revenue under the arrangement on a straight‑line basis over the period the Company is expected to complete its performance obligations. Conversely, if the pattern of performance in which the service is provided to the customer can be determined and objectively measurable performance measures exist, then the Company recognizes revenue under the arrangement using the proportional performance method. Revenue recognized is limited to the lesser of the cumulative amount of payments received or the cumulative amount of revenue earned, as determined using the straight‑line method or proportional performance method, as applicable, as of the period ending date. The Company recognizes revenue associated with milestones in accordance with the provisions of ASC Topic 605-28, Revenue Recognition-Milestone Method The Company will recognize royalty revenue in the period of sale of the related product(s), based on the underlying contract terms, provided that the reported sales are reliably measurable and the Company has no remaining performance obligations, assuming all other revenue recognition criteria are met. Collaborative Arrangements The Company records the elements of its collaboration agreements that represent joint operating activities in accordance with ASC Topic 808, Collaborative Arrangements Revenue Recognition—Principal Agent Considerations During the three months ended September 30, 2017, the Company incurred approximately $0.3 million of costs related to the cost-sharing provisions of the Otsuka U.S. Agreement of which approximately $0.1 million are reimbursable by Otsuka and recorded as a reduction to research and development expense during the three months ended September 30, 2017. Patents Costs incurred in connection with the application for and issuance of patents are expensed as incurred. Income Taxes Income taxes are recorded in accordance with FASB Topic 740, Income Taxes The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of September 30, 2017 and 2016, the Company does not have any significant uncertain tax positions. The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. Stock-Based Compensation The Company accounts for its stock-based compensation awards in accordance with ASC Topic 718, Compensation—Stock Compensation Equity-Based Payments to Non-Employees The Black-Scholes option pricing model requires the input of certain subjective assumptions, including (a) the expected stock price volatility, (b) the calculation of expected term of the award, (c) the risk-free interest rate and (d) expected dividends. Due to the lack of company-specific historical and implied volatility data for trading the Company’s stock in the public market, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The computation of expected volatility is based on the historical volatility of a representative group of companies with similar characteristics to the Company, including stage of product development and life science industry focus. During 2017, the Company began to estimate its volatility by using a blend of its stock price history for the length of time it has market data for its stock and the historical volatility of similar public companies for the expected term of each grant. The Company is in the product development stage with no product revenue and the representative group of companies has certain similar characteristics to the Company. The Company believes the group selected has sufficient similar economic and industry characteristics, and includes companies that are most representative of the Company. The Company uses the simplified method as prescribed by the SEC Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its employee population. For options granted to non-employees, the Company utilizes the contractual term of the arrangement as the basis for the expected term assumption. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected life of the stock options. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock, which is similar to the Company’s peer group. The Company’s stock-based awards are subject to service based vesting conditions. Compensation expense related to awards to employees with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Consistent with the guidance in ASC 505- 50, compensation expense related to awards to non-employees with service-based vesting conditions is recognized on a straight-line basis based on the then-current fair value at each financial reporting date prior to the measurement date over the associated service period of the award, which is generally the vesting term. The Company adopted ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, recognized Fair Value of Financial Instruments The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. ASC Topic 820, Fair Value Measurements and Disclosures Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments, and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below: • Level 1 – Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. • Level 2 – Valuations based on quoted prices for similar assets or liabilities in markets that are not active, or for which all significant inputs are observable, either directly or indirectly. • Level 3 – Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Items measured at fair value on a recurring basis include short-term investments (see Note 4). The carrying amounts of prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to their short-term maturities. The rate implicit within the Company’s capital lease obligation approximates market interest rates. Concentrations of Credit Risk and Off-Balance Sheet Risk Cash and investments are the only financial instruments that potentially subject the Company to concentrations of credit risk. The Company maintains its cash with high quality, accredited financial institutions and, accordingly, such funds are subject to minimal credit risk. The Company has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements. Net Loss per Share Basic net loss per share is calculated by dividing net loss by the weighted-average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting weighted-average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the diluted net loss per share calculation, preferred stock, stock options, warrants, unvested restricted stock and RSUs are considered to be common stock equivalents, but have been excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive for all periods presented. Therefore, basic and diluted net loss per share were the same for all periods presented. Property and Equipment Property and equipment is stated at cost, less accumulated depreciation. Assets under capital lease are included in property and equipment. Property and equipment is depreciated using the straight-line method over the estimated useful lives of the assets, generally three to seven years. Such costs are periodically reviewed for recoverability when impairment indicators are present. Such indicators include, among other factors, operating losses, unused capacity, market value declines and technological obsolescence. Recorded values of asset groups of equipment that are not expected to be recovered through undiscounted future net cash flows are written down to current fair value, which generally is determined from estimated discounted future net cash flows (assets held for use) or net realizable value (assets held for sale). The following is the summary of property and equipment and related accumulated depreciation as of September 30, 2017 and December 31, 2016. Useful Life September 30, 2017 December 31, 2016 (in thousands) Computer equipment and software 3 $ 589 $ 476 Furniture and fixtures 5 800 729 Equipment 7 348 50 Leasehold improvements Shorter of the useful life or remaining lease term (10 years) 2,453 1,763 Office equipment under capital lease 3 36 36 4,226 3,054 Less accumulated depreciation (862 ) (442 ) Net property and equipment $ 3,364 $ 2,612 Depreciation expense, including expense associated with assets under capital leases, was approximately $0.2 million

Strategic Collaborations and Ot

Strategic Collaborations and Other Significant Agreements	9 Months Ended
	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Strategic Collaborations and Other Significant Agreements	3. Strategic Collaborations and Other Significant Agreements Mitsubishi Tanabe Pharma Corporation Collaboration Agreement Summary of Agreement On December 11, 2015, the Company and MTPC entered into a collaboration agreement, the MTPC Agreement, providing MTPC with exclusive development and commercialization rights to vadadustat, the Company’s product candidate for the treatment of anemia related to chronic kidney disease, in Japan and certain other Asian countries, collectively, the Territory. Pursuant to the MTPC Agreement, MTPC has an exclusive license to develop and commercialize vadadustat in the Territory. In addition, the Company will supply vadadustat for both clinical and commercial use in the Territory. The Company and MTPC agreed to pursue a local development plan and, following consultation with the Japanese Pharmaceuticals and Medical Devices Agency, or the PMDA, MTPC initiated a local Phase 3 development for vadadustat in Japan, the Local Scenario. In consideration for the exclusive license and other rights contained in the MTPC Agreement, under the Local Scenario Japanese patients would not be included in the Phase 3 program and MTPC would make payments totaling up to $245.0 million based on the achievement of certain development, regulatory and sales milestones, as well as tiered double-digit royalty payments up to 20% on sales of vadadustat in the Territory. Under the Local Scenario, MTPC is responsible for the costs of local development in Japan and will make no additional funding payments for the global Phase 3 program. The Company recently completed its Phase 2 study of vadadustat in non-dialysis-dependent, NDD, Japanese patients and is currently conducting its Phase 2 study of vadadustat in dialysis-dependent Japanese patients in Japan and expects findings by the end of 2017. Under the Local Scenario, these Phase 2 studies are considered local development costs and reimbursable by MTPC. Therefore, of the $40.0 million received by the Company in 2016, $20.0 million is being applied towards costs already incurred by the Company for the Phase 2 studies and MTPC will reimburse the Company for costs in excess of $20.0 million to complete the studies. The Company has incurred approximately $17.4 million in Phase 2 costs through September 2017 and anticipates incurring an additional approximately $8.0 million in Phase 2 costs through the end of the studies. As a result, MTPC would be required to reimburse the Company an additional approximately $5.0 million related to the two Phase 2 studies. Pursuant to the terms of the MTPC Agreement for the Local Scenario, MTPC is responsible for performing all Phase 3 activities related to the development of vadadustat in the Territory and has sole responsibility for the commercialization of vadadustat in the Territory as well as for Medical Affairs (as defined in the MTPC Agreement) in the Territory. Akebia is responsible for the completion of Phase 2 dosing studies as reimbursed by MTPC, manufacturing and supplying vadadustat for clinical use in the Territory and, if approved by the FDA, will enter into a supply agreement with MTPC for the commercial supply of vadadustat prior to commercial launch. The Company and MTPC have established a joint steering committee pursuant to the agreement to oversee development and commercialization of vadadustat in the Territory, including approval of any development or commercialization plans. Unless earlier terminated, the MTPC Agreement will continue in effect on a country-by-country basis until the later of: expiration of the last-to-expire patent covering vadadustat in such country in the Territory; expiration of marketing or regulatory exclusivity in such country in the Territory; or ten years after the first commercial sale of vadadustat in such country in the Territory. MTPC may terminate the MTPC Agreement upon twelve months’ notice at any time after the second anniversary of the effective date of the MTPC Agreement. Either party may terminate the MTPC Agreement upon the material breach of the other party that is not cured within a specified time period or upon the insolvency of the other party. Under the Local Scenario, MTPC is required to make certain milestone payments to the Company aggregating to approximately $225.0 million upon the achievement of specified development, regulatory and commercial events. More specifically, the Company is eligible to receive up to $10.0 million in development milestone payments, up to $40.0 million in regulatory milestone payments for the first product to achieve the associated event and up to $175.0 million in commercial milestone payments associated with aggregate sales of all products. Additionally, if vadadustat is commercialized, the Company would be entitled to receive tiered royalty payments in the low double digits based on a percentage of net sales. Royalty payments are subject to certain reductions, including upon the introduction of competitive products in certain instances. Royalties are due on a country-by-country basis from the date of first commercial sale of a licensed product in a country until the last to occur of: (i) the expiration of the last to expire valid claim within the intellectual property covering the licensed product, (ii) the expiration of marketing or regulatory exclusivity in such country, or (iii) the tenth anniversary of the first commercial sale of such licensed product in such country. Due to the uncertainty of pharmaceutical development and the high historical failure rates associated with drug development, no milestone or royalty payments may ever be received from MTPC. In September 2017, the Company and MTPC entered into a new agreement that provided MTPC with an option to access data from the Company’s global Phase 3 vadadustat program for payments to the Company of up to $25.0 million. Revenue Recognition The Company evaluated the elements of the MTPC Agreement in accordance with the provisions of ASC 605-25. The Company’s arrangement with MTPC contains the following deliverables: (i) license under certain of the Company’s intellectual property to develop and commercialize vadadustat (the License Deliverable), (ii) clinical supply of vadadustat, (iii) knowledge transfer, (iv) Phase 2 dosing study research services, and (v) rights to future know-how. The Company has identified two units of accounting in connection with its obligations under the MTPC Agreement. Factors considered in making the assessment of standalone value included, among other things, the capabilities of the collaboration partner, whether any other vendor sells the item separately, whether the value of the deliverable is dependent on the other elements in the arrangement, whether there are other vendors that can provide the items and if the customer could use the item for its intended purpose without the other deliverables in the arrangement. Additionally, the License Agreement does not include a general right of return. The two units of accounting identified in connection with the Company’s obligations under the MTPC Agreement are as follows: (i) License, Research Services and Clinical Supply Unit of Accounting The License Deliverable does not have standalone value and qualify for separation from the clinical supply of vadadustat. More specifically, the license delivered to MTPC does not provide the contractual right to manufacture vadadustat. MTPC is contractually prohibited from manufacturing any Licensed Product covered by the licenses during clinical trials. Accordingly, MTPC must obtain the clinical trial products from the Company which significantly limits the ability for MTPC to use the license for their intended use on a standalone basis. The License Deliverable does not have standalone value and qualify for separation from the knowledge transfer because MTPC cannot fully utilize the license for its intended purpose without the corresponding information regarding know-how, development data and regulatory materials possessed by the Company. The License Deliverable does not have standalone value and qualify for separation from the Phase 2 dosing study research services because MTPC cannot fully utilize the license for its intended purpose without the performance of the Phase 2 dosing studies. The Phase 2 dosing studies need to be performed prior to the PMDA approving any Phase 3 study to be performed in the Territory. Furthermore, MTPC cannot benefit from the Phase 2 dosing studies without the license and the undelivered Phase 3 clinical supply. The License Deliverable does not have standalone value from the clinical supply, knowledge transfer or Phase 2 studies. As a result, the License Deliverable, clinical supply, knowledge transfer and Phase 2 studies have been combined as a single unit of accounting (the License, Research and Clinical Supply Unit of Accounting) (ii) Rights to Future Know-How The License, Research and Clinical Supply Unit of Accounting has standalone value and qualifies for separation from the rights to future know how because MTPC can obtain the value of the License, Research and Clinical Supply Unit of Accounting without receipt of any rights to future know how that may be discovered or developed in the future. The Company has determined that neither VSOE of selling price nor TPE of selling price is available for either of the units of accounting identified at inception of the arrangement with MTPC. Accordingly, the selling price of each unit of accounting was determined based on the Company’s BESP. The Company developed the BESP with the objective of determining the price at which it would sell such an item if it were to be sold regularly on a standalone basis. The Company developed the BESP for the Rights to Future Know How Unit of Accounting primarily based on the likelihood that additional intellectual property covered by the license conveyed will be developed during the term of the arrangement. The Company did not develop a BESP for the License, Research and Clinical Supply Unit of Accounting because the BESP associated with the Rights to Future Know How Unit of Accounting was determined to be immaterial. The Company has concluded that a change in the key assumptions used to determine the BESP for each unit of accounting would not have a significant impact on the allocation of arrangement consideration. Allocable arrangement consideration is comprised of: (i) the up-front payment of $20.0 million, (ii) the estimate of the cost for the Phase 2 studies of at least $20.0 million, and (iii) the cost of all clinical supply provided to MTPC for the Phase 3 studies. No amounts were allocated to the Rights to Know How Unit of Accounting because the associated BESP was determined to be immaterial therefore the arrangement consideration will be allocated to the License, Research Services and Clinical Supply Unit of Accounting. The has evaluated all the development, regulatory sales milestones may received in connection with the MTPC Agreement. In evaluating if milestone is substantive, assesses whether: (i) consideration is commensurate with either Company’s to achieve the milestone the of value of delivered item(s) result of specific resulting performance to achieve milestone, (ii) the relates to performance, and (iii) the consideration is reasonable relative to all the deliverables and payment terms within the arrangement. All regulatory milestones, with the exception of one development milestone associated with the near term progress of the Phase 3 study, substantive contingent nature the milestone, specifically reviewing factors scientific, clinical, regulatory, commercial other risks must overcome to achieve the milestone well as level of effort investment Accordingly, amounts will recognized revenue in full in in which the associated milestone is all other revenue recognition criteria are met. The non-substantive development milestone will be included in the arrangement consideration, if and when received, and allocated to the License, Research Services and Clinical Unit of Accounting within the arrangement and recognized as revenue when those underlying obligations are satisfied. The total aggregate amount of development milestones is million and total aggregate of milestones is up to million. All milestones, up to $175.0 million, will accounted for in same manner royalties recorded revenue upon achievement the milestone, assuming all . The will recognize royalty revenue in sale of related product(s), the terms, that the sales measurable and no performance obligations, other revenue recognition criteria met. Revenue for the fixed and determinable consideration of $40.0 million that was received in January 2016, will be recognized, using a proportional performance method, as the Company delivers clinical supply of vadadustat to MTPC for the Phase 3 study. The Company expects to begin to deliver the clinical supply of vadadustat to MTPC in the fourth quarter of 2017. Therefore, at September 30, 2017 the $40.0 million is recorded as deferred revenue in the accompanying consolidated balance sheets. Otsuka Pharmaceutical Co. Ltd. U.S. Collaboration and License Agreement Summary of Agreement On December 18, 2016, the Company entered into a collaboration and license agreement with Otsuka, or the Otsuka U.S. Agreement. The collaboration is focused on the development and commercialization of vadadustat in the United States. Under the terms of the Otsuka U.S. Agreement, the Company will continue to lead the development of vadadustat, including the ongoing Phase 3 development program. The Company and Otsuka will co-commercialize vadadustat in the United States, subject to the approval of vadadustat by the FDA. Under the terms of the Otsuka U.S. Agreement, the Company granted to Otsuka a co-exclusive, non-sublicensable license under certain intellectual property controlled by the Company solely to perform medical affairs activities and to conduct non-promotional and commercialization activities related to vadadustat in accordance with the associated plans. The co-exclusive license relates to activities that will be jointly conducted by the Company and Otsuka pursuant to the terms of the Otsuka U.S. Agreement. Pursuant to the terms of the Otsuka U.S. Agreement, the Company is responsible for performing all activities related to the development of vadadustat as outlined in the current global development plan. The current global development plan encompasses all activities with respect to the ongoing PRO 2 2 Under the Otsuka U.S. Agreement, the parties jointly conduct, and have equal responsibility for, all medical affairs, commercialization and non-promotional activities pursuant to underlying plans as agreed to by the parties. If approved by the FDA, the Company will provide vadadustat to Otsuka for commercialization pursuant to a separate supply agreement to be negotiated. The activities under the Otsuka U.S. Agreement are governed by a joint steering committee, or JSC, formed by an equal number of representatives from the Company and Otsuka. The JSC coordinates and monitors the parties’ activities under the collaboration. Among other responsibilities, the JSC manages the overall strategic alignment between the parties, oversees the current global development plan and reviews the other detailed plans setting forth the parties’ activities under the arrangement, including the medical affairs plan and commercialization and non-promotional activities plan. Additionally, the parties established a joint development committee, or JDC, which is comprised of an equal number of representatives from the Company and Otsuka. Among other responsibilities, the JDC will share information related to, and review and discuss activities and progress under, the current global development plan and any other development that may be conducted pursuant to the collaboration. In support of the potential commercialization of vadadustat, the parties will establish a joint commercialization committee, or JCC, which will be comprised of an equal number of representatives from the Company and Otsuka. Among other responsibilities, the JCC will manage the activities and progress under the commercialization and non-promotional activities plan and all other sales and marketing activities. The Company has retained the final decision‑making authority with respect to all development matters, pricing strategy and certain other key commercialization matters. Under the terms of the Otsuka U.S. Agreement, the Company received a $125.0 million up-front, non-refundable, non-creditable cash payment in December 2016. In March 2017, the Company received a payment of approximately $33.8 million, which represents reimbursement for Otsuka’s share of costs previously incurred by the Company in implementing the current global development plan through December 31, 2016. Going forward, Otsuka will contribute a percentage of the remaining costs to be incurred under the current global development plan subsequent to December 31, 2016, commencing upon the date on which the Company has incurred a specified amount of incremental costs. The Company estimates that Otsuka’s funding of the current global development plan costs subsequent to December 31, 2016 will total $153.6 million or more. The costs associated with the performance of any development activities in addition to those outlined in the current global development plan will be subject to a cost sharing or reimbursement mechanism to be determined by the parties. Costs incurred with respect to medical affairs and commercialization and non-promotional activities will generally be shared equally by the parties. Either party’s share of the medical affairs and/or commercialization activities may be increased at such party’s request upon mutual agreement of the parties. In addition, if the costs incurred in completing the activities under the current global development plan exceed a certain threshold, then the Company may elect to require Otsuka to fund a higher percentage of the current global development costs. In such event, the excess of the payments made under such election and Otsuka’s allocated share of the current global development costs is fully creditable against future payments due to the Company under the arrangement. In addition, Otsuka would be required to make certain milestone payments to the Company upon the achievement of specified development, regulatory and commercial events. More specifically, the Company is eligible to receive up to $125.0 million in development milestone payments and up to $65.0 million in regulatory milestone payments for the first product to achieve the associated event. Moreover, the Company is eligible for up to $575.0 million in commercial milestone payments associated with aggregate sales of all products. Due to the uncertainty of pharmaceutical development and the high historical failure rates associated therewith, no milestone payments may ever be received from Otsuka. Under the Otsuka U.S. Agreement, the Company and Otsuka share the costs of developing and commercializing vadadustat in the United States and the profits from the sales of vadadustat after approval by the FDA. In connection with the profit share calculation, net sales include gross sales to third-party customers net of discounts, rebates, chargebacks, taxes, freight and insurance charges and other applicable deductions. Shared costs generally include costs attributable or reasonably allocable to the manufacture of vadadustat for commercialization purposes and the performance of medical affairs activities, non-promotional activities and commercialization activities. Under the Otsuka U.S. Agreement, Otsuka originally had a limited period of time in which it can exercise an option to convert the arrangement from a profit share to a right to receive a mid-single digit royalty on future net sales of commercialized products (the Royalty Conversion Option). On August 4, 2017, Otsuka agreed to waive its right to exercise the Royalty Conversion Option in advance of its expiration, consequently, Otsuka has no further right to elect to exercise this option. Unless earlier terminated, the Agreement will expire on a country-by-country and product-by-product basis on the date that one or more generic versions of vadadustat first achieves 90% market penetration. Either party may terminate the Otsuka U.S. Agreement in its entirety upon an uncured breach or insolvency on the part of the other party. Otsuka may terminate the Otsuka U.S. Agreement in its entirety upon 12 months’ prior written notice at any time after the release of the first topline data from the global Phase 3 development program. In the event of termination of the Otsuka U.S. Agreement, all rights and licensees granted to Otsuka under the Otsuka U.S. Agreement will automatically terminate and the licenses granted to the Company will become freely sublicensable. In addition, the upfront payment, all development costs and milestone payments received by the Company prior to such termination will not be refunded to Otsuka. Revenue Recognition The Company evaluated the elements of the Otsuka US Agreement in accordance with the provisions of ASC 605-25. The Company’s arrangement with Otsuka contains the following deliverables: (i) license under certain of the Company’s intellectual property to develop, perform medical affairs activities with respect to and conduct non-promotional and commercialization activities related to vadadustat and products containing or comprising vadadustat (the License Deliverable), (ii) development services to be performed pursuant to the current global development plan (the Development Services Deliverable), (iii) rights to future intellectual property (the Future IP Deliverable), and (iv) joint committee services (the Committee Deliverable). The Company has identified three units of accounting in connection with its obligations under the Otsuka U.S. Agreement. Factors considered in making the assessment of standalone value included, among other things, the capabilities of the collaboration partner, whether any other vendor sells the item separately, whether the value of the deliverable is dependent on the other elements in the arrangement, whether there are other vendors that can provide the items and if the customer could use the item for its intended purpose without the other deliverables in the arrangement. Additionally, the Otsuka U.S. Agreement does not include a general right of return. The three units of accounting identified in connection with the Company’s obligations under the Otsuka U.S. Agreement are as follows: (i) License and Development Services Combined (License Unit of Accounting) The License Deliverable does not qualify for separation from the Development Services Deliverable, due to the contractual limitations inherent in the license conveyed. More specifically, Otsuka does not have the contractual right to manufacture vadadustat and products containing or comprising vadadustat. However, the manufacturing and supply services that are conducted as part of the services to be performed pursuant to the current global development plan are necessary for Otsuka to fully exploit the associated license for its intended purpose. The value of the rights provided through the license conveyed will be realized when the underlying products covered by the intellectual property progress through the development cycle, receive regulatory approval and are commercialized. Products containing or comprising vadadustat cannot be commercialized until the development services under the current global development plan are completed. Accordingly, Otsuka must obtain the manufacturing and supply of the associated products that is included within the development services to be performed pursuant to the current global development plan from the Company in order to derive benefit from the license which significantly limits the ability for Otsuka to utilize the License Deliverable for its intended purpose on a standalone basis. (ii) Rights to Future Intellectual Property The License Deliverable and the Development Services Deliverable qualify for separation from the Future IP Deliverable because Otsuka can obtain the value of the license using the clinical trial materials implicit in the development services without the receipt of any other intellectual property that may be discovered or developed in the future. The Future IP Deliverable qualifies for separation from the Committee Deliverable because the joint committee services have no bearing on the value to be derived from the rights to potential future intellectual property. (iii) Joint Committee Services The License Deliverable and Development Services Deliverable qualify for separation from the Committee Deliverable because Otsuka can obtain the value of the license using the clinical trial materials implicit in the development services without the joint committee services. The Committee Deliverable has standalone value from the rights to Future IP Deliverable because the joint committee services have no bearing on the value to be derived from the rights to potential future intellectual property. The Company has determined that neither VSOE of selling price nor TPE of selling price is available for any of the units of accounting identified at inception of the arrangement with Otsuka. Accordingly, the selling price of each unit of accounting was determined based on the Company’s BESP. The Company developed the BESP with the objective of determining the price at which it would sell such an item if it were to be sold regularly on a standalone basis. In developing the BESP for the Joint Committee Services Unit of Accounting, the Company considered the nature of the services to be performed and estimates of the associated effort and rates applicable to such services that would be expected to be realized under similar contracts. The Company developed the BESP for the Rights to Future Intellectual Property Unit of Accounting primarily based on the likelihood that additional intellectual property covered by the license conveyed will be developed during the term of the arrangement. The Company did not develop a BESP for the License Unit of Accounting due to the following: (i) the BESP associated with the Rights to Future Intellectual Property Unit of Accounting was determined to be immaterial and (ii) the period of performance and pattern of recognition for the License Unit of Accounting and the Joint Committee Services Unit of Accounting was determined to be similar. The Company has concluded that a change in the key assumptions used to determine the BESP for each unit of accounting would not have a significant impact on the allocation of arrangement consideration. Allocable arrangement consideration at inception is comprised of: (i) the up-front payment of $125.0 million, (ii) the cost share payment with respect to amounts incurred by the Company through December 31, 2016 of $33.8 million, and (iii) an estimate of the cost share payments to be received with respect to amounts incurred by the Company subsequent to December 31, 2016 of $153.6 million. No amounts were allocated to the Rights to Future Intellectual Property Unit of Accounting because the associated BESP was determined to be immaterial. Due to the similar performance period and recognition pattern between the License Unit of Accounting and the Joint Committee Services Unit of Accounting, the arrangement consideration totaling $312.4 million has been allocated to the License Unit of Accounting and the Joint Committee Services Unit of Accounting on a combined basis. Accordingly, the Company will recognize revenue related to the allocable arrangement consideration on a proportional performance basis as the underlying development services are performed pursuant to the current global development plan which is commensurate with the period and consistent with the pattern over which the Company’s obligations are satisfied for both the License Unit of Accounting and the Joint Committee Services Unit of Accounting. Effectively, the Company has treated the arrangement as if the License Unit of Accounting and the Joint Committee Services Unit of Accounting are a single unit of accounting. The has evaluated all the development, regulatory commercial milestones may received in connection with the Otsuka U.S. Agreement. In evaluating if milestone is substantive, assesses whether: (i) consideration is commensurate with either Company’s to achieve the milestone the of value of delivered item(s) result of specific resulting performance to achieve milestone, (ii) the relates to performance, and (iii) the consideration is reasonable relative to all the deliverables and payment terms within the arrangement. All regulatory milestones substantive contingent nature the milestone, specifically reviewing factors scientific, clinical, regulatory, commercial other risks must overcome to achieve the milestone well as level of effort investment Accordingly, amounts will recognized revenue in full in in which the associated milestone is all other revenue recognition met. All milestones will be recorded revenue upon achievement of the milestone, assuming all revenue recognition met. During the three and nine months ended September 30, 2017, the Company recognized revenue totaling approximately $22.5 million and $60.0 million, respectively, with respect to the Otsuka U.S. Agreement. The revenue is classified as collaboration revenue in the accompanying consolidated statement of operations. As of September 30, 2017, there is approximately $97.3 million of deferred revenue related to the Otsuka U.S. Agreement of which $48.5 million is classified as current and $48.8 million is classified as long-term in the accompanying consolidated balance sheet based on the performance period of the underlying obligations. The Company determined that the medical affairs, commercialization and non-promotional activities elements of the Otsuka U.S. Agreement represent joint operating activities in which both parties are active participants and of which both parties are exposed to significant risks and rewards that are dependent on the success of the activities. Accordingly, the Company is accounting for the joint medical affairs, commercialization and non-promotional activities in accordance with ASC No. 808, Collaborative Arrangements Revenue Recognition–Multiple-Element Arrangements During the three months ended September 30, 2017, the Company incurred approximately $0.3 million of costs related to the cost-sharing provisions of the Otsuka U.S. Agreement of which approximately $0.1 million are reimbursable by Otsuka and recorded as a reduction to research and development expense during the three months ended September 30, 2017. Otsuka Pharmaceutical Co. Ltd. EU Collaboration and License Agreement Summary of Agreement On April 25, 2017, the Company entered into a collaboration and license agreement with Otsuka, the Otsuka EU Agreement. The collaboration is focused on the development and commercialization of vadadustat in Europe, Russia, China, Canada, Australia, the Middle East and certain other territories, collectively, the Territory. Under the terms of the Otsuka EU Agreement, the Company will continue to lead the development of vadadustat, including the ongoing global Phase 3 development program. Otsuka has the sole responsibility, at its own cost, for the commercialization of vadadustat in the Territory, subject to the approval by the relevant regulatory authorities. Under the terms of the Otsuka EU Agreement, the Company granted to Otsuka an exclusive, sublicensable license under certain intellectual property controlled by the Company to develop and commercialize vadadustat and products containing or comprising vadadustat in the Territory. Pursuant to the terms of the Otsuka EU Agreement, the Company is responsible for performing all activities related to the development of vadadustat as outlined in the current global development plan; however, the parties may agree to allocate certain responsibilities to Otsuka. The current global development plan encompasses all activities with respect to the ongoing PRO 2 2 Under the Otsuka EU Agreement, Otsuka is to be solely responsible for the conduct of all medical affairs and commercialization activities in the Territory pursuant to underlying plans as reviewed and discussed by the parties. If approved by the relevant jurisdictional regulatory health authorities in the Territory, the Company will provide vadadustat to Otsuka for commercialization pursuant to a separate supply agreement to be negotiated

Available for Sale Securities

Available for Sale Securities	9 Months Ended
	Sep. 30, 2017
Investments Debt And Equity Securities [Abstract]
Available for Sale Securities	4. Available for sale securities Available for sale securities at September 30, 2017 and December 31, 2016 consist of the following : Gross Gross Unrealized Unrealized Amortized Cost Gains Losses Fair Value (in thousands) September 30, 2017 Cash and cash equivalents $ 89,599 $ — $ — $ 89,599 Available for sale securities: Certificates of deposit $ 17,788 — — $ 17,788 U.S. Government debt securities 152,913 — (144 ) 152,769 Corporate debt securities 69,587 2 (40 ) 69,549 Total available for sale securities $ 240,288 $ 2 $ (184 ) $ 240,106 Total cash, cash equivalents, and available for sale securities $ 329,887 $ 2 $ (184 ) $ 329,705 Gross Gross Unrealized Unrealized Amortized Cost Gains Losses Fair Value (in thousands) December 31, 2016 Cash and cash equivalents $ 187,335 $ — $ — $ 187,335 Available for sale securities: Certificates of deposit $ 12,698 — — $ 12,698 U.S. Government debt securities 50,952 — (32 ) 50,920 Corporate debt securities 9,398 — (8 ) 9,390 Total available for sale securities $ 73,048 $ — $ (40 ) $ 73,008 Total cash, cash equivalents, and available for sale securities $ 260,383 $ — $ (40 ) $ 260,343 The estimated fair value of the Company’s available for sale securities balance at September 30, 2017, by contractual maturity, is as follows: Due in one year or less $ 217,429 Due after one year 22,677 Total available for sale securities $ 240,106

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	5. Fair Value of Financial Instruments The Company utilizes a portfolio management company for the valuation of the majority of its investments. This company is an independent, third-party vendor recognized to be an industry leader with access to market information that obtains or computes fair market values from quoted market prices, pricing for similar securities, recently executed transactions, cash flow models with yield curves and other pricing models. For valuations obtained from the pricing service, the Company performs due diligence to understand how the valuation was calculated or derived, focusing on the valuation technique used and the nature of the inputs. Based on the fair value hierarchy, the Company classifies its cash equivalents and marketable securities within Level 1 or Level 2. This is because the Company values its cash equivalents and marketable securities using quoted market prices or alternative pricing sources and models utilizing market observable inputs. Assets measured or disclosed at fair value on a recurring basis as of September 30, 2017 and December 31, 2016 are summarized below: Fair Value Measurements Using Level 1 Level 2 Level 3 Total (in thousands) September 30, 2017 Assets: Cash and cash equivalents $ 89,599 $ — $ — $ 89,599 Certificates of deposit — 17,788 — 17,788 U.S. Government debt securities — 152,769 — 152,769 Corporate debt securities — 69,549 — 69,549 $ 89,599 $ 240,106 $ — $ 329,705 Fair Value Measurements Using Level 1 Level 2 Level 3 Total (in thousands) December 31, 2016 Assets: Cash and cash equivalents $ 187,335 $ — $ — $ 187,335 Certificates of deposit — 12,698 — 12,698 U.S. Government debt securities — 50,920 — 50,920 Corporate debt securities — 9,390 — 9,390 $ 187,335 $ 73,008 $ — $ 260,343 The Company’s corporate debt securities are all investment grade. The Company had no assets or liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) at September 30, 2017 and December 31, 2016. Investment securities are exposed to various risks such as interest rate, market and credit risks. Due to the level of risk associated with certain investment securities and the level of uncertainty related to changes in the value of investment securities, it is at least reasonably possible that changes in risks in the near term would result in material changes in the fair value of investments.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2017
Payables And Accruals [Abstract]
Accrued Expenses	6. Accrued Expenses Accrued expenses are as follows: September 30, 2017 December 31, 2016 (in thousands) Accrued clinical expenses $ 13,977 $ 23,643 Accrued bonus 2,403 2,995 Accrued professional fees 1,541 539 Accrued vacation 691 513 Accrued payroll 536 596 Accrued other 2,279 1,975 Total accrued expenses $ 21,427 $ 30,261

Warrant

Warrant	9 Months Ended
	Sep. 30, 2017
Warrant Disclosure [Abstract]
Warrant	7. Warrant In connection with the Janssen Agreement, in February 2017 the Company issued a warrant to purchase 509,611 shares of the Company’s common stock at an exercise price of $9.81 per share. The warrant is fully vested upon issuance and exercisable in whole or in part, at any time prior to the fifth anniversary of the date of issuance. The warrant satisfied the equity classification criteria of ASC 815, and is therefore classified as an equity instrument. The fair value at issuance of $3.4 million was calculated using the Black Scholes option pricing model and was charged to research and development expense as it represented consideration for a license for which the underlying intellectual property was deemed to have no alternative future use. As of September 30, 2017, the warrant remains outstanding and expires on February 9, 2022.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	8. Stockholders’ Equity Authorized and Outstanding Capital Stock As of September 30, 2017, the authorized capital stock of the Company included 175,000,000 shares of common stock, par value $0.00001 per share, of which 47,238,001 and 38,615,709 shares are issued and outstanding at September 30, 2017 and December 31, 2016, respectively; and 25,000,000 shares of undesignated preferred stock, par value $0.00001 per share, of which 0 shares are issued and outstanding at September 30, 2017 and December 31, 2016. Equity Plans On February 28, 2014, the Company’s Board of Directors adopted its 2014 Incentive Plan (the “2014 Plan”) and its 2014 Employee Stock Purchase Plan (the “ESPP”), which were subsequently approved by its stockholders and became effective upon the closing of the Company’s initial public offering on March 25, 2014. The 2014 Plan replaced the 2008 Equity Incentive Plan (as amended, the “2008 Plan”); however, options or other awards granted under the 2008 Plan prior to the adoption of the 2014 Plan that have not been settled or forfeited remain outstanding and effective. In May 2016 the Company’s Board of Directors approved an inducement award program that was separate from the Company’s equity plans and which, consistent with NASDAQ listing rules, did not require shareholder approval (the 2016 program and similar programs, each an “Inducement Award Program”) under which 350,000 shares were reserved to be issued in 2016 and awards relating to 255,000 shares were granted and remain eligible to vest. The Company continues to grant inducement awards to new hires under a 2017 authorization. The 2014 Plan allows for the granting of stock options, stock appreciation rights (SARs), restricted stock, unrestricted stock, restricted stock units (RSUs), performance awards and other awards convertible into or otherwise based on shares of our common stock. Dividend equivalents may also be provided in connection with an award under the 2014 Plan. The Company’s employees, officers, directors and consultants and advisors are eligible to receive awards under the 2014 Plan. The Company initially reserved 1,785,000 shares of its common stock for the issuance of awards under the 2014 Plan. The 2014 Plan provides that the number of shares reserved and available for issuance under the 2014 Plan will automatically increase annually on January 1 st st st The ESPP provides for the issuance of options to purchase shares of the Company’s common stock to participating employees at a discount to their fair market value. The maximum aggregate number of shares of common stock available for purchase pursuant to the exercise of options granted under the ESPP will be the lesser of (a) 262,500 shares, increased on each anniversary of the adoption of the ESPP by one percent (1%) of the total shares of common stock then outstanding (the “ESPP Evergreen Provision”) and (b) 739,611 shares (which is equal to five percent (5%) of the total shares of common stock outstanding on the date of the adoption of the ESPP on a fully diluted, as converted basis. Under the ESPP, each offering period is six months, at the end of which employees may purchase shares of common stock through payroll deductions made over the term of the offering. The per-share purchase price at the end of each offering period is equal to the lesser of eighty-five percent (85%) of the closing price of our common stock at the beginning or end of the offering period. Shares Reserved for Future Issuance The Company has reserved for future issuance the following number of shares of common stock: September 30, 2017 December 31, 2016 Common stock options and RSUs outstanding 4,471,741 3,579,694 Shares available for issuance under the 2014 Plan (1) 1,003,137 885,328 Warrant to purchase common stock 509,611 — Shares available for issuance under the ESPP (2) 652,290 803,105 Total 6,636,779 5,268,127 (1) On January 1, 2017 and January 1, 2016, the shares reserved for future grants under the 2014 Plan increased by 1,265,863 and 986,800 shares, respectively, pursuant to the 2014 Plan Evergreen Provision. (2) On February 28, 2016, the shares reserved for future issuance under the ESPP increased by 273,404 shares pursuant to the ESPP Evergreen Provision. Stock-Based Compensation Stock Options On February 21, 2017, as part of the Company’s annual grant of equity, the Company issued 719,400 stock options to employees. In addition, the Company issues stock options to new hires and occasionally to other employees not in connection with the annual grant process. Options granted by the Company vest over periods of between 12 and 48 months, subject, in each case, to the individual’s continued service through the applicable vesting date. Options vest in installments of (i) 25% at the one year anniversary and (ii) in either 36 or 48 equal monthly or 12 equal quarterly installments beginning in the thirteenth month after the initial vesting commencement date or grant date, subject to the individual’s continuous service with the Company. Options generally expire ten years after the date of grant. The Company recorded approximately $1.6 million and approximately $1.2 million of stock-based compensation expense related to stock options during the three months ended September 30, 2017 and 2016, respectively and approximately $4.9 million and $3.4 million during the nine months ended September 30, 2017 and 2016, respectively. Restricted Stock On December 23, 2013, the Company issued 450,224 shares of restricted stock to employees and 79,067 shares of restricted stock to non-employees at a grant date fair value of $7.42 per share. The aggregate grant date fair value for the shares of restricted stock issued on December 23, 2013 totaled approximately $3.9 million. The awards of restricted stock contained a performance condition wherein vesting is contingent upon the Company’s consummation of a liquidity event, as defined, prior to the fifth anniversary of the date of grant. Certain of the awards of restricted stock have a requisite service period that was complete upon grant. The remainder of the awards of restricted stock have a requisite service period of four years whereby the award vests 25% on the one year anniversary of the Vesting Commencement Date (as defined), then ratably on the first day of each calendar quarter for 12 quarters, subject to continuous service by the individual and achievement of the performance target. Due to the nature of the performance condition, the Company had concluded that the performance condition was not probable of achievement and therefore, recognition of compensation cost had been deferred until the occurrence of a liquidity event, as defined. Compensation expense related to the restricted stock awards is being recognized over the associated requisite service period which commenced on March 25, 2014. The Company recorded approximately $0.1 million of stock-based compensation expense related to restricted stock during each of the three months ended September 30, 2017 and 2016, and approximately $0.2 million and $0.1 million during the nine months ended September 30, 2017 and 2016, respectively, as a result of mark to market adjustments related to non-employees. Restricted Stock Units On February 21, 2017, as part of the Company’s annual grant of equity, the Company issued 423,650 RSUs to employees. In addition, the Company occasionally issues RSUs not in connection with the annual grant process to employees. 100% of each RSU grant vests on the third anniversary of the grant date, subject, in each case, to the individual’s continued service through the applicable vesting date. Total stock-compensation expense to be recognized over the life of the RSUs is $2.9 million and will be recognized on a straight-line basis over the vesting period. The Company recorded approximately $0.4 million and $0.2 million of stock-based compensation expense related to the RSUs during the three months ended September 30, 2017 and 2016, respectively, and approximately $1.5 million and $0.5 million during the nine months ended September 30, 2017 and 2016, respectively. Employee Stock Purchase Plan T Stock-Based Compensation Expense Summary The Company has classified its stock-based compensation expense related to share-based awards as follows: Three months ended Nine months ended September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 (in thousands) (in thousands) Research and development $ 569 $ 636 $ 5,741 $ 1,393 General and administrative 1,584 992 4,346 2,708 Total $ 2,153 $ 1,628 $ 10,087 $ 4,101 Compensation expense by type of award: Three months ended Nine months ended September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 (in thousands) (in thousands) Stock options $ 1,606 $ 1,229 $ 4,927 $ 3,378 Restricted stock 93 135 158 148 Restricted stock units 407 232 1,458 496 Employee stock purchase plan 47 32 131 79 Warrant — — 3,413 — Total $ 2,153 $ 1,628 $ 10,087 (1) $ 4,101 (1) This amount includes $3.4 million of fair value related to the warrants issued to Janssen

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using statutory rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. There were no significant income tax provisions or benefits for the three months ended September 30, 2017 and 2016. Due to the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has recorded a full valuation allowance against the Company’s otherwise recognizable net deferred tax assets.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies The Company leases approximately 45,362 square feet of office and lab space in Cambridge, Massachusetts under a lease which was most recently amended in July 2016, collectively, the Lease. Total monthly lease payments for base rent are approximately $242,000 per month which is subject to annual rent escalations. In addition to such annual rent escalations, base rent payments for a portion of said premises commenced on January 1, 2017 in the monthly amount of approximately $22,000. Landlord contributions included in the Lease from the landlord totaled $2,169,920, including $70,526 in leasehold improvements not yet utilized. The landlord contributions are being accounted for as a deferred lease incentive and reduction in monthly rent expense over the term of the Lease. The term of the Lease with respect to the office space expires on September 11, 2026, with one five year extension option available. The term of the Lease for the lab space is five years, with an extension option for one additional period of two years. The total security deposit in connection with the Lease of $1,280,857 is included in other assets in the Company’s condensed consolidated balance sheets as of September 30, 2017 and December 31, 2016. The Company recognizes rent expense and records a deferred lease obligation representing the cumulative difference between actual facility lease payments and lease expense recognized ratably over the lease period, which is included in the Company’s condensed consolidated balance sheets as of September 30, 2017 and December 31, 2016. Under the Lease, the Company took possession of the remaining 3,384 square feet of office space on January 1, 2017, and subleased this space on that date (the Sublease) as it did not intend to use the space for its operations. The term of the Sublease is two years and the monthly rent to be received by the Company is approximately $22,000. Under the Sublease, the Company’s operating lease obligations through 2018 are partially offset by the receipt of future Sublease payments of approximately $0.3 million. The total security deposit in connection with the Sublease of $21,432, which is due within 30 days from the execution of the Sublease, is included in other current assets and other liabilities in the Company’s condensed consolidated balance sheets. The Company leases office equipment under three year capital leases with payments commencing in February 2014, April 2015 and February 2016, respectively. The capital lease amounts are included in accrued expenses and other liabilities. At September 30, 2017, the Company’s future minimum payments required under these leases are as follows: Lease Payments Operating to be Received Net Operating Capital Lease from Sublease Lease Payments Lease Total (in thousands) 2017 $ 886 $ 64 $ 822 $ 2 $ 824 2018 3,545 257 $ 3,288 5 $ 3,293 2019 3,545 — $ 3,545 — $ 3,545 2020 3,545 — $ 3,545 — $ 3,545 2021 3,510 — $ 3,510 — $ 3,510 Thereafter 14,666 — $ 14,666 — $ 14,666 Total $ 29,697 $ 321 $ 29,376 7 $ 29,383 Less amount representing interest — Present value of minimum lease payments at September 30, 2017 $ 7 The Company recorded approximately $0.8 million and $0.6 million in rent expense for the three months ended September 30, 2017 and 2016, respectively, and approximately $2.4 million and $1.7 million for the nine months ended September 30, 2017 and 2016, respectively. Under the Company’s agreement with a subsidiary of Quintiles IMS Holdings, Inc., or Quintiles, to provide services for the PRO 2 2 In July 2011, a third party filed an opposition to our issued European Patent No. 2044005, or the ’005 Patent. During the oral proceedings, which took place on April 10, 2013, the Opposition Division of the European Patent Office maintained the ’005 Patent on the basis of the third auxiliary request filed during the oral proceedings. This decision resulted in the maintenance of a claim directed to a compound chosen from a group of eight compounds, including vadadustat, as well as claims to compositions and methods for treating various diseases, including, but not limited to, anemia. Both parties have appealed the decision of the Opposition Division and a hearing has been scheduled for May 8, 2018. The Company cannot be assured of the breadth of the claims that will remain in the ’005 Patent or that the patent will not be revoked in its entirety. The Company has had a number of positive developments in its opposition and invalidity proceedings against FibroGen, Inc., or FibroGen. With regard to the opposition that the Company filed in Europe against FibroGen’s European Patent No. 1463823, or the ’823 patent, an oral proceeding took place March 8 and 9, 2016. Following the oral proceeding, the European Opposition Division ruled that the patent as granted did not meet the requirements for patentability under the European Patent Convention and, therefore, revoked the patent in its entirety. FibroGen has appealed that decision and the appeal process is expected to take 2 to 3 years. Likewise, with regard to the invalidity proceeding that the Company filed in Japan against certain claims of FibroGen’s Japanese Patent No. 4804131, or the ’131 patent, which is the Japanese counterpart to the ’823 patent, the Japan Patent Office, or JPO, issued a preliminary decision finding all of the challenged claims to be invalid. FibroGen subsequently amended the claims and the JPO accepted the amendments. The resulting FibroGen Japanese ’131 patent does not cover vadadustat or any pyridine carboxamide compounds. To date, FibroGen has been unsuccessful in its attempts to obtain a patent in the United States covering the same claim scope as it obtained initially in Europe and Japan in the ’823 and ’131 patents. In the event FibroGen were to obtain such a patent in the United States, the Company may decide to challenge them like the Company has done in Europe and Japan. With regard to the opposition that we filed in Europe against FibroGen’s European Patent No. 163333, or the ’333 patent, an oral proceeding took place December 8 and 9, 2016. Following the oral proceeding, the European Opposition Division ruled that the patent as granted did not meet the requirements for patentability under the European Patent Convention and, therefore, revoked the patent in its entirety. FibroGen has appealed that decision. On May 13, 2015, May 20, 2015 and July 6, 2015, the Company filed oppositions to FibroGen’s European Patent Nos. 2322153, 2322155, and 1633333, or the ’153 patent, the ’155 patent, and the ’333 patent, respectively, requesting the patents be revoked in their entirety. These related patents claim, among other things, various compounds that either stabilize HIFα or inhibit a HIF hydroxylase or a HIF prolyl hydroxylase for treating or preventing various conditions, including, inter alia The Company’s policy is to record a liability if a loss in a significant legal dispute is considered probable and an amount can be reasonably estimated. The Company provides disclosure when a loss in excess of any reserve is reasonably possible, and the Company is in a position to estimate the potential loss or range of possible loss. Significant judgment is required to assess the likelihood of various potential outcomes and the quantification of loss in those scenarios. The Company’s estimates change as litigation progresses and new information comes to light. Changes in Company estimates could have a material impact on the Company’s results and financial position.

Employee Retirement Plan

Employee Retirement Plan	9 Months Ended
	Sep. 30, 2017
Compensation And Retirement Disclosure [Abstract]
Employee Retirement Plan	11. Employee Retirement Plan During 2008, the Company established a retirement plan (the Plan) authorized by Section 401(k) of the Internal Revenue Code. In accordance with the Plan, all employees who have attained the age of 21 are eligible to participate in the Plan as of the first Entry Date, as defined therein, following their date of employment. Each employee can contribute a percentage of compensation up to a maximum of the statutory limits per year. Company contributions are discretionary and contributions in the amount of approximately $27,000 and $21,000 were made during the three months ended September 30, 2017 and 2016, respectively, and approximately $0.2 million and $0.1 million during the nine months ended September 30, 2017 and 2016, respectively.

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Net Loss per Share	12. Net Loss per Share The shares in the table below were excluded from the calculation of diluted net loss per share, prior to the use of the treasury stock method, due to their anti-dilutive effect: As of September 30, 2017 2016 Warrants 509,611 — Outstanding stock options 3,743,303 2,977,986 Unvested restricted stock 13,982 132,739 Unvested restricted stock units 728,438 438,563 Total 4,995,334 3,549,288

Summary of Significant Accoun18

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Akebia Therapeutics Securities Corporation and Akebia Europe Limited. All intercompany balances and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (U.S. GAAP). Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (ASC) and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB). In the quarter ended June 30, 2017, we identified and corrected an immaterial error in the amount of research and development expenses related to our global Phase 3 study of vadadustat. This adjustment also affected the amount of revenue recognized pursuant to our license and collaboration agreements with Otsuka. The adjustments impacted our results of operations in each quarter of 2016 and the first quarter of 2017. We concluded the effect of these adjustments was not material to our consolidated financial statements for any prior period.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard-setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In February 2016, the FASB issued ASU 2016-02, Leases In May 2014, the FASB issued a new revenue recognition standard which amends revenue recognition principles and provides a single, comprehensive set of criteria for revenue recognition within and across all industries. The new standard provides a five-step framework whereby revenue is recognized when promised goods or services are transferred to a customer at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard also requires enhanced disclosures pertaining to revenue recognition in both interim and annual periods. In August 2015, the FASB deferred the effective date of the new revenue standard from January 1, 2017 to January 1, 2018. Early adoption is permitted any time after the original effective date, which for us was January 1, 2017. The Company intends to adopt the new standard on January 1, 2018. The standard allows for adoption using a full retrospective method or a modified retrospective method. The Company’s historical revenue has been derived from its collaboration agreements with Otsuka Pharmaceutical Co. Ltd., or Otsuka. The Company will commence revenue recognition under its collaboration agreement with Mitsubishi Tanabe Pharma Corporation, or MTPC, when it begins to deliver the clinical supply of vadadustat to MTPC which the Company expects to be in the fourth quarter of 2017. These arrangements contain multiple-elements and have been accounted for pursuant to Revenue Recognition Multiple‑Element Arrangements . The new revenue standard provides guidance in assessing what comprises the distinct service being provided to a customer that may have implications to our performance obligations and unit of account identified in our three existing collaborations which could be defined differently under the new guidance. As a result, there could be changes to the timing of revenue recognition upon adoption of the new standard. The Company is currently assessing the impact of the new revenue recognition standard on its collaboration agreements with MTPC and Otsuka and evaluating which method it will adopt.
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment, which is the business of developing and commercializing proprietary therapeutics based on HIF biology.
Derivative Financial Instruments	Derivative Financial Instruments The Company accounts for warrants and other derivative financial instruments as either equity or liabilities in accordance with ASC Topic 815, Derivatives and Hedging (ASC 815) based upon the characteristics and provisions of each instrument. Warrants classified as equity are recorded at fair value as of the date of issuance on the Company’s consolidated balance sheets and no further adjustments to their valuation are made. Warrants classified as derivative liabilities and other derivative financial instruments that require separate accounting as liabilities are recorded on the Company’s consolidated balance sheets at their fair value on the date of issuance and will be revalued on each subsequent balance sheet date until such instruments are exercised or expire, with any changes in the fair value between reporting periods recorded as other income or expense. The warrant issued by the Company in connection with the Janssen Pharmaceutica NV Research and License Agreement, the Janssen Agreement, is classified as equity in the Company’s condensed consolidated bal ance sheet. (See Note 7).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, among others: prepaid and accrued research and development expense, stock-based compensation expense, revenue and income taxes.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of all cash on hand, deposits and funds invested in available-for-sale securities with original maturities of three months or less at the time of purchase. At September 30, 2017, the Company’s cash is primarily in money market funds. The Company may maintain balances with its banks in excess of federally insured limits.
Investments	Investments Management determines the appropriate classification of securities at the time of purchase and reevaluates such designation as of each balance sheet date. Currently, the Company classifies all securities as available-for-sale which are included in current assets as they are intended to fund current operations. The Company carries available-for-sale securities at fair value. The Company conducts periodic reviews to identify and evaluate each investment that has an unrealized loss, in accordance with the meaning of other-than-temporary impairment and its application to certain investments. When assessing whether a decline in the fair value of a security is other-than-temporary, the Company considers the fair market value of the security, the duration of the security’s decline, and prospects for the underlying business. Based on these considerations, the Company did not identify any other-than-temporary unrealized losses at September 30, 2017. Unrealized losses on available-for-sale securities that are determined to be temporary, and not related to credit loss, are recorded in accumulated other comprehensive loss, a component of stockholders’ equity. The amortized cost of debt securities in this category reflects amortization of premiums and accretion of discounts to maturity computed under the effective interest method. The Company includes this amortization in the caption “Interest income” within the consolidated statements of operations and comprehensive loss. The Company also includes in net investment income, realized gains and losses and declines in value determined to be other than temporary. The Company bases the cost of securities sold upon the specific identification method, and includes interest and dividends on securities in interest income.
Revenue Recognition	Revenue Recognition To date, the Company has not generated any revenue from the sales of products. For the foreseeable future, the Company expects substantially all of its revenues will be generated from its collaborations with MTPC and Otsuka (see Note 3) and any other collaborations the Company may enter into. Multiple-Element Arrangements The Company recognizes revenue in accordance with ASC Topic 605, Revenue Recognition • Persuasive evidence of an arrangement exists; • Delivery has occurred or services have been rendered; • The seller’s price to the buyer is fixed or determinable; and • Collectability is reasonably assured. Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified in current liabilities. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Revenue recognition from our MTPC collaboration will commence when we begin to deliver the clinical supply of vadadustat to MTPC which the Company expects to begin in the fourth quarter of 2017. Therefore, collaboration revenue in the current period is exclusively from our collaborations agreements with Otsuka. The terms of these arrangements contain multiple deliverables, which include at inception: (i) license, (ii) development services, (iii) rights to future intellectual property and (iv) joint committee services. Non-refundable payments to the Company under these arrangements include: (i) up-front fee, (ii) payments for development services and (iii) payments based on the achievement of certain milestones. Also, under the Otsuka U.S. Agreement, the Company and Otsuka share costs incurred with respect to jointly conducted medical affairs and commercialization and non-promotional activities under the collaboration. Additionally, the Company may receive its share of net sales and bear its share of shared costs from the sale of products containing or comprising vadadustat in the United States through its U.S. collaboration with Otsuka. The Company will recognize revenue related to amounts allocated to the License Unit of Accounting on a proportional performance basis as the underlying services are performed. The Company evaluates multiple‑element arrangements based on the guidance in ASC 605‑25. Pursuant to the guidance in ASC 605‑25, the Company evaluates multiple‑element arrangements to determine (i) the deliverables included in the arrangement and (ii) whether the individual deliverables represent separate units of accounting or whether they must be accounted for as a combined unit of accounting. This evaluation involves subjective determinations and requires the Company to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. Deliverables are considered separate units of accounting provided that: (i) the delivered item(s) has value to the customer on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company’s control. In assessing whether an item has standalone value, the Company considers factors such as the research, development, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can use the other deliverable(s) for their intended purpose without the receipt of the remaining deliverable(s), whether the value of the deliverable is dependent on the undelivered item and whether there are other vendors that can provide the undelivered item(s). The Company’s collaboration arrangements do not contain a general right of return relative to delivered item(s). Arrangement consideration that is fixed or determinable is allocated among the separate units of accounting using the relative selling price method. The Company determines the selling price for a unit of accounting following the hierarchy of evidence prescribed by ASC 605-25. Accordingly, the Company determines the estimated selling price for units of accounting within each arrangement using vendor‑specific objective evidence (VSOE) of selling price, if available, third‑party evidence (TPE) of selling price if VSOE is not available, or best estimate of selling price (BESP) if neither VSOE nor TPE is available. Determining the BESP for a unit of accounting requires significant judgment. In developing the BESP for a unit of accounting, the Company considers applicable market conditions and relevant entity‑specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. The Company validates the BESP for units of accounting by evaluating whether changes in the key assumptions used to determine the BESP will have a significant effect on the allocation of arrangement consideration between multiple units of accounting. The Company recognizes arrangement consideration allocated to each unit of accounting when all of the revenue recognition criteria in ASC 605 are satisfied for that particular unit of accounting. The Company recognizes as revenue arrangement consideration attributed to licenses that have standalone value from other deliverables to be provided in an arrangement upon delivery. The Company recognizes as revenue arrangement consideration attributed to licenses that do not have standalone value from the other deliverables to be provided in an arrangement over the contractual or estimated performance period associated with the undelivered elements included in the combined unit of accounting, which is typically the term of the Company’s development obligations. If there is no discernible pattern of performance and/or objectively measurable performance measures do not exist, then the Company recognizes revenue under the arrangement on a straight‑line basis over the period the Company is expected to complete its performance obligations. Conversely, if the pattern of performance in which the service is provided to the customer can be determined and objectively measurable performance measures exist, then the Company recognizes revenue under the arrangement using the proportional performance method. Revenue recognized is limited to the lesser of the cumulative amount of payments received or the cumulative amount of revenue earned, as determined using the straight‑line method or proportional performance method, as applicable, as of the period ending date. The Company recognizes revenue associated with milestones in accordance with the provisions of ASC Topic 605-28, Revenue Recognition-Milestone Method The Company will recognize royalty revenue in the period of sale of the related product(s), based on the underlying contract terms, provided that the reported sales are reliably measurable and the Company has no remaining performance obligations, assuming all other revenue recognition criteria are met. Collaborative Arrangements The Company records the elements of its collaboration agreements that represent joint operating activities in accordance with ASC Topic 808, Collaborative Arrangements Revenue Recognition—Principal Agent Considerations During the three months ended September 30, 2017, the Company incurred approximately $0.3 million of costs related to the cost-sharing provisions of the Otsuka U.S. Agreement of which approximately $0.1 million are reimbursable by Otsuka and recorded as a reduction to research and development expense during the three months ended September 30, 2017.
Patents	Patents Costs incurred in connection with the application for and issuance of patents are expensed as incurred.
Income Taxes	Income Taxes Income taxes are recorded in accordance with FASB Topic 740, Income Taxes The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of September 30, 2017 and 2016, the Company does not have any significant uncertain tax positions. The Company recognizes interest and penalties related to uncertain tax positions in income tax expense.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for its stock-based compensation awards in accordance with ASC Topic 718, Compensation—Stock Compensation Equity-Based Payments to Non-Employees The Black-Scholes option pricing model requires the input of certain subjective assumptions, including (a) the expected stock price volatility, (b) the calculation of expected term of the award, (c) the risk-free interest rate and (d) expected dividends. Due to the lack of company-specific historical and implied volatility data for trading the Company’s stock in the public market, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The historical volatility is calculated based on a period of time commensurate with the expected term assumption. The computation of expected volatility is based on the historical volatility of a representative group of companies with similar characteristics to the Company, including stage of product development and life science industry focus. During 2017, the Company began to estimate its volatility by using a blend of its stock price history for the length of time it has market data for its stock and the historical volatility of similar public companies for the expected term of each grant. The Company is in the product development stage with no product revenue and the representative group of companies has certain similar characteristics to the Company. The Company believes the group selected has sufficient similar economic and industry characteristics, and includes companies that are most representative of the Company. The Company uses the simplified method as prescribed by the SEC Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term for options granted to employees as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its employee population. For options granted to non-employees, the Company utilizes the contractual term of the arrangement as the basis for the expected term assumption. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected life of the stock options. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on its common stock, which is similar to the Company’s peer group. The Company’s stock-based awards are subject to service based vesting conditions. Compensation expense related to awards to employees with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Consistent with the guidance in ASC 505- 50, compensation expense related to awards to non-employees with service-based vesting conditions is recognized on a straight-line basis based on the then-current fair value at each financial reporting date prior to the measurement date over the associated service period of the award, which is generally the vesting term. The Company adopted ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, recognized
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. ASC Topic 820, Fair Value Measurements and Disclosures Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments, and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below: • Level 1 – Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. • Level 2 – Valuations based on quoted prices for similar assets or liabilities in markets that are not active, or for which all significant inputs are observable, either directly or indirectly. • Level 3 – Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Items measured at fair value on a recurring basis include short-term investments (see Note 4). The carrying amounts of prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to their short-term maturities. The rate implicit within the Company’s capital lease obligation approximates market interest rates.
Concentrations of Credit Risk and Off-Balance Sheet Risk	Concentrations of Credit Risk and Off-Balance Sheet Risk Cash and investments are the only financial instruments that potentially subject the Company to concentrations of credit risk. The Company maintains its cash with high quality, accredited financial institutions and, accordingly, such funds are subject to minimal credit risk. The Company has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.
Net Loss per Share	Net Loss per Share Basic net loss per share is calculated by dividing net loss by the weighted-average shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by adjusting weighted-average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the diluted net loss per share calculation, preferred stock, stock options, warrants, unvested restricted stock and RSUs are considered to be common stock equivalents, but have been excluded from the calculation of diluted net loss per share, as their effect would be anti-dilutive for all periods presented. Therefore, basic and diluted net loss per share were the same for all periods presented.
Property and Equipment	Property and Equipment Property and equipment is stated at cost, less accumulated depreciation. Assets under capital lease are included in property and equipment. Property and equipment is depreciated using the straight-line method over the estimated useful lives of the assets, generally three to seven years. Such costs are periodically reviewed for recoverability when impairment indicators are present. Such indicators include, among other factors, operating losses, unused capacity, market value declines and technological obsolescence. Recorded values of asset groups of equipment that are not expected to be recovered through undiscounted future net cash flows are written down to current fair value, which generally is determined from estimated discounted future net cash flows (assets held for use) or net realizable value (assets held for sale). The following is the summary of property and equipment and related accumulated depreciation as of September 30, 2017 and December 31, 2016. Useful Life September 30, 2017 December 31, 2016 (in thousands) Computer equipment and software 3 $ 589 $ 476 Furniture and fixtures 5 800 729 Equipment 7 348 50 Leasehold improvements Shorter of the useful life or remaining lease term (10 years) 2,453 1,763 Office equipment under capital lease 3 36 36 4,226 3,054 Less accumulated depreciation (862 ) (442 ) Net property and equipment $ 3,364 $ 2,612 Depreciation expense, including expense associated with assets under capital leases, was approximately $0.2 million

Summary of Significant Accoun19

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Property and Equipment and Related Accumulated Depreciation	The following is the summary of property and equipment and related accumulated depreciation as of September 30, 2017 and December 31, 2016. Useful Life September 30, 2017 December 31, 2016 (in thousands) Computer equipment and software 3 $ 589 $ 476 Furniture and fixtures 5 800 729 Equipment 7 348 50 Leasehold improvements Shorter of the useful life or remaining lease term (10 years) 2,453 1,763 Office equipment under capital lease 3 36 36 4,226 3,054 Less accumulated depreciation (862 ) (442 ) Net property and equipment $ 3,364 $ 2,612

Available for Sale Securities (

Available for Sale Securities (Tables)	9 Months Ended
	Sep. 30, 2017
Investments Debt And Equity Securities [Abstract]
Summary of Available for Sale Securities at Fair Value	Available for sale securities at September 30, 2017 and December 31, 2016 consist of the following : Gross Gross Unrealized Unrealized Amortized Cost Gains Losses Fair Value (in thousands) September 30, 2017 Cash and cash equivalents $ 89,599 $ — $ — $ 89,599 Available for sale securities: Certificates of deposit $ 17,788 — — $ 17,788 U.S. Government debt securities 152,913 — (144 ) 152,769 Corporate debt securities 69,587 2 (40 ) 69,549 Total available for sale securities $ 240,288 $ 2 $ (184 ) $ 240,106 Total cash, cash equivalents, and available for sale securities $ 329,887 $ 2 $ (184 ) $ 329,705 Gross Gross Unrealized Unrealized Amortized Cost Gains Losses Fair Value (in thousands) December 31, 2016 Cash and cash equivalents $ 187,335 $ — $ — $ 187,335 Available for sale securities: Certificates of deposit $ 12,698 — — $ 12,698 U.S. Government debt securities 50,952 — (32 ) 50,920 Corporate debt securities 9,398 — (8 ) 9,390 Total available for sale securities $ 73,048 $ — $ (40 ) $ 73,008 Total cash, cash equivalents, and available for sale securities $ 260,383 $ — $ (40 ) $ 260,343
Estimated Fair Value of Available for Sale Securities by Contractual Maturity	The estimated fair value of the Company’s available for sale securities balance at September 30, 2017, by contractual maturity, is as follows: Due in one year or less $ 217,429 Due after one year 22,677 Total available for sale securities $ 240,106

Fair Value of Financial Instr21

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Assets Measured or Disclosed at Fair Value on Recurring Basis	Assets measured or disclosed at fair value on a recurring basis as of September 30, 2017 and December 31, 2016 are summarized below: Fair Value Measurements Using Level 1 Level 2 Level 3 Total (in thousands) September 30, 2017 Assets: Cash and cash equivalents $ 89,599 $ — $ — $ 89,599 Certificates of deposit — 17,788 — 17,788 U.S. Government debt securities — 152,769 — 152,769 Corporate debt securities — 69,549 — 69,549 $ 89,599 $ 240,106 $ — $ 329,705 Fair Value Measurements Using Level 1 Level 2 Level 3 Total (in thousands) December 31, 2016 Assets: Cash and cash equivalents $ 187,335 $ — $ — $ 187,335 Certificates of deposit — 12,698 — 12,698 U.S. Government debt securities — 50,920 — 50,920 Corporate debt securities — 9,390 — 9,390 $ 187,335 $ 73,008 $ — $ 260,343

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2017
Payables And Accruals [Abstract]
Components of Accrued Expenses	Accrued expenses are as follows: September 30, 2017 December 31, 2016 (in thousands) Accrued clinical expenses $ 13,977 $ 23,643 Accrued bonus 2,403 2,995 Accrued professional fees 1,541 539 Accrued vacation 691 513 Accrued payroll 536 596 Accrued other 2,279 1,975 Total accrued expenses $ 21,427 $ 30,261

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Summary of Reserved Shares of Common Stock for Future Issuance	The Company has reserved for future issuance the following number of shares of common stock: September 30, 2017 December 31, 2016 Common stock options and RSUs outstanding 4,471,741 3,579,694 Shares available for issuance under the 2014 Plan (1) 1,003,137 885,328 Warrant to purchase common stock 509,611 — Shares available for issuance under the ESPP (2) 652,290 803,105 Total 6,636,779 5,268,127 (1) On January 1, 2017 and January 1, 2016, the shares reserved for future grants under the 2014 Plan increased by 1,265,863 and 986,800 shares, respectively, pursuant to the 2014 Plan Evergreen Provision. (2) On February 28, 2016, the shares reserved for future issuance under the ESPP increased by 273,404 shares pursuant to the ESPP Evergreen Provision.
Stock-Based Compensation Expense Related to Share-Based Awards	The Company has classified its stock-based compensation expense related to share-based awards as follows: Three months ended Nine months ended September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 (in thousands) (in thousands) Research and development $ 569 $ 636 $ 5,741 $ 1,393 General and administrative 1,584 992 4,346 2,708 Total $ 2,153 $ 1,628 $ 10,087 $ 4,101
Schedule of Compensation Expense by Type of Award	Compensation expense by type of award: Three months ended Nine months ended September 30, 2017 September 30, 2016 September 30, 2017 September 30, 2016 (in thousands) (in thousands) Stock options $ 1,606 $ 1,229 $ 4,927 $ 3,378 Restricted stock 93 135 158 148 Restricted stock units 407 232 1,458 496 Employee stock purchase plan 47 32 131 79 Warrant — — 3,413 — Total $ 2,153 $ 1,628 $ 10,087 (1) $ 4,101 (1) This amount includes $3.4 million of fair value related to the warrants issued to Janssen

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments Required Under Leases	At September 30, 2017, the Company’s future minimum payments required under these leases are as follows: Lease Payments Operating to be Received Net Operating Capital Lease from Sublease Lease Payments Lease Total (in thousands) 2017 $ 886 $ 64 $ 822 $ 2 $ 824 2018 3,545 257 $ 3,288 5 $ 3,293 2019 3,545 — $ 3,545 — $ 3,545 2020 3,545 — $ 3,545 — $ 3,545 2021 3,510 — $ 3,510 — $ 3,510 Thereafter 14,666 — $ 14,666 — $ 14,666 Total $ 29,697 $ 321 $ 29,376 7 $ 29,383 Less amount representing interest — Present value of minimum lease payments at September 30, 2017 $ 7

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share	The shares in the table below were excluded from the calculation of diluted net loss per share, prior to the use of the treasury stock method, due to their anti-dilutive effect: As of September 30, 2017 2016 Warrants 509,611 — Outstanding stock options 3,743,303 2,977,986 Unvested restricted stock 13,982 132,739 Unvested restricted stock units 728,438 438,563 Total 4,995,334 3,549,288

Nature of Organization and Op26

Nature of Organization and Operations - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Nature Of Organization And Operations [Line Items]
Cash and cash equivalents and available for sale securities	$ 329,705	$ 260,343
Number of months for operating plan sufficiently funded by cash resources	12 months

Summary of Significant Accoun27

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)Segment	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | Segment			1
Cost share payment received					$ 33,800,000
Significant uncertain tax positions	$ 0	$ 0	$ 0	$ 0
Expected dividend yield			0.00%
Depreciation expense	200,000	$ 100,000	$ 400,000	$ 200,000
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, Useful life			3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, Useful life			7 years
Otsuka U.S. Agreement
Summary Of Significant Accounting Policies [Line Items]
Cost share payment received	300,000
Reimbursable by Otsuka	$ 100,000

Summary of Significant Accoun28

Summary of Significant Accounting Policies - Summary of Property and Equipment and Related Accumulated Depreciation (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 4,226	$ 3,054
Less accumulated depreciation	(862)	(442)
Net property and equipment	$ 3,364	2,612
Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Useful life	7 years
Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Useful life	3 years
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Useful life	3 years
Gross property, plant and equipment	$ 589	476
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Useful life	5 years
Gross property, plant and equipment	$ 800	729
Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Useful life	7 years
Gross property, plant and equipment	$ 348	50
Leasehold improvements
Property, Plant and Equipment [Line Items]
Leasehold improvements, Useful Life	Shorter of the useful life or remaining lease term (10 years)
Gross property, plant and equipment	$ 2,453	1,763
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Useful life	10 years
Office equipment under capital lease
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Useful life	3 years
Gross property, plant and equipment	$ 36	$ 36

Strategic Collaborations and 29

Strategic Collaborations and Other Significant Agreements - Additional Information (Details)	Apr. 25, 2017USD ($)	Apr. 02, 2017USD ($)	Jan. 02, 2017USD ($)	Sep. 30, 2017USD ($)$ / sharesshares	May 31, 2017USD ($)$ / sharesshares	Mar. 31, 2017USD ($)	Feb. 28, 2017USD ($)$ / sharesshares	Sep. 30, 2017USD ($)$ / sharesshares	Mar. 31, 2017USD ($)	Sep. 30, 2017USD ($)AccountingUnit$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										$ 236,700,000
Number of accounting units | AccountingUnit										3
Deferred revenue, noncurrent				$ 84,701,000				$ 84,701,000		$ 84,701,000	$ 115,321,000
Cost share payment received											33,800,000
Estimated cost share payment receivable			$ 153,600,000
Allocated arrangement consideration										312,400,000
Recognized revenue under license agreement								41,283,000		90,668,000
Deferred revenue, current				$ 121,031,000				$ 121,031,000		$ 121,031,000	$ 81,968,000
Common stock shares sold | shares				47,238,001				47,238,001		47,238,001	38,615,709
Common stock, par value | $ / shares				$ 0.00001				$ 0.00001		$ 0.00001	$ 0.00001
Upfront
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											$ 125,000,000
Otsuka U.S. Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue, noncurrent				$ 48,800,000				$ 48,800,000		$ 48,800,000
Cost share payment received								300,000
Deferred revenue, current				48,500,000				48,500,000		48,500,000
Reimbursable by Otsuka								100,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										0
Additional milestone payments to be received as development costs under local scenario										0
Development costs incurred										17,400,000
Expected additional development costs										8,000,000
Expected reimbursement for development costs										$ 5,000,000
Collaboration Agreement, expiration period										10 years
Collaboration Agreement, notice period for termination										12 months
Number of accounting units | AccountingUnit										2
Deferred revenue, noncurrent				40,000,000				40,000,000		$ 40,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated cost										20,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Development Regulatory And Sales Milestones | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										$ 245,000,000
Percentage of royalty payments on sales										20.00%
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Upfront
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										$ 20,000,000	40,000,000
Incurred clinical and commercial development cost										20,000,000
Milestone revenue refundable				20,000,000				20,000,000		20,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Development, Regulatory and Commercial Events
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										225,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Development Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										10,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Development Milestones | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										10,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Regulatory Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										40,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Commercial Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										175,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Approval Milestones | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										65,000,000
Mitsubishi Tanabe Pharma Corporation | Development and Commercialize Collaboration Agreement | Sales Milestones | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										175,000,000
Mitsubishi Tanabe Pharma Corporation | New Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue				25,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										$ 0
Percentage of market penetration for license agreement										90.00%
License agreement, notice period for termination										12 months
Recognized revenue under license agreement								22,500,000		$ 60,000,000
Deferred revenue				97,300,000				97,300,000		97,300,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement for Otsuka's share of costs previously incurred						$ 33,800,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Minimum | Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated fund			$ 153,600,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Development Milestones | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										125,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Regulatory Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										65,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Commercial Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue										575,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize United States Collaboration and License Agreement | Up-front, Non-refundable and Non-creditable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue											$ 125,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize European Union Collaboration and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue, noncurrent				31,300,000				31,300,000		31,300,000
Recognized revenue under license agreement								18,800,000		30,700,000
Deferred revenue				63,800,000				63,800,000		63,800,000
Deferred revenue, current				$ 32,500,000				$ 32,500,000		$ 32,500,000
Milestone or royalty payments received	$ 0
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize European Union Collaboration and License Agreement | Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reimbursement for Otsuka's share of costs previously incurred									$ 200,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize European Union Collaboration and License Agreement | Minimum | Global Development Plan
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated fund		$ 163,600,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize European Union Collaboration and License Agreement | Development Milestones | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue	80,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize European Union Collaboration and License Agreement | Regulatory Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue	52,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize European Union Collaboration and License Agreement | Commercial Milestone Payments | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue	525,000,000
Otsuka Pharmaceutical Company. Ltd. | Development and Commercialize European Union Collaboration and License Agreement | Up-front, Non-refundable and Non-creditable
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue	$ 73,000,000
Janssen Pharmaceutica NV | Development and Commercialize Research and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration Agreement, expiration period							10 years
Collaboration Agreement, notice period for termination							180 days
Upfront payment made in cash							$ 1,000,000
Warrant to purchase common stock, shares | shares							509,611
Fair value of warrant						3,400,000			3,400,000
Aggregate specified development milestone payments payable							$ 16,500,000
Specified commercial milestones as well as tiered, escalating royalties payable							$ 215,000,000
Johnson & Johnson Innovation | Development and Commercialize Research and License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Warrant to purchase common stock, shares | shares							509,611
Fair value of warrant						$ 3,400,000			$ 3,400,000
Exercise price | $ / shares							$ 9.81
Vifor (International) Ltd. | License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone revenue					$ 20,000,000
Deferred revenue, noncurrent					$ 4,700,000
License agreement, notice period for termination					12 months
Common stock shares sold | shares					3,571,429
Common stock, par value | $ / shares					$ 0.00001
Sale of stock, price per share | $ / shares					$ 14
Proceeds from common stock sold					$ 50,000,000
Premium over the closing stock price of common stock | $ / shares					$ 12.69
Premium amount over the closing stock price of common stock					$ 4,700,000

Available for Sale Securities -

Available for Sale Securities - Summary of Available for Sale Securities at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 240,288	$ 73,048
Gross Unrealized Gains	2
Gross Unrealized Losses	(184)	(40)
Fair Value	240,106	73,008
Cash and cash equivalents	89,599	187,335	$ 65,830	$ 49,778
Cash and cash equivalents, Fair Value	89,599	187,335
Total cash, cash equivalents, and available for sale securities - Amortized Cost	329,887	260,383
Total cash, cash equivalents, and available for sale securities - Fair Value	329,705	260,343
U.S. Government debt securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	152,913	50,952
Gross Unrealized Losses	(144)	(32)
Fair Value	152,769	50,920
Certificates of deposit
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	17,788	12,698
Fair Value	17,788	12,698
Corporate debt securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	69,587	9,398
Gross Unrealized Gains	2
Gross Unrealized Losses	(40)	(8)
Fair Value	$ 69,549	$ 9,390

Available for Sale Securities31

Available for Sale Securities - Estimated Fair Value of Available for Sale Securities by Contractual Maturity (Details) $ in Thousands	Sep. 30, 2017USD ($)
Investments Debt And Equity Securities [Abstract]
Due in one year or less	$ 217,429
Due after one year	22,677
Total available for sale securities	$ 240,106

Fair Value of Financial Instr32

Fair Value of Financial Instruments - Assets Measured or Disclosed at Fair Value on Recurring Basis (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	$ 0	$ 0
Fair value measurements recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	329,705,000	260,343,000
Fair value measurements recurring | U.S. Government debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	152,769,000	50,920,000
Fair value measurements recurring | Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	89,599,000	187,335,000
Fair value measurements recurring | Certificates of deposit
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	17,788,000	12,698,000
Fair value measurements recurring | Corporate debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	69,549,000	9,390,000
Fair value measurements recurring | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	89,599,000	187,335,000
Fair value measurements recurring | Level 1 | Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	89,599,000	187,335,000
Fair value measurements recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	240,106,000	73,008,000
Fair value measurements recurring | Level 2 | U.S. Government debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	152,769,000	50,920,000
Fair value measurements recurring | Level 2 | Certificates of deposit
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	17,788,000	12,698,000
Fair value measurements recurring | Level 2 | Corporate debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	$ 69,549,000	$ 9,390,000

Fair Value of Financial Instr33

Fair Value of Financial Instruments - Additional Information (Details) - Level 3 - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Measured at fair value on recurring basis	$ 0	$ 0
Liabilities measured at fair value on recurring basis	$ 0	$ 0

Accrued Expenses - Components o

Accrued Expenses - Components of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accrued clinical expenses	$ 13,977	$ 23,643
Accrued bonus	2,403	2,995
Accrued professional fees	1,541	539
Accrued vacation	691	513
Accrued payroll	536	596
Accrued other	2,279	1,975
Total accrued expenses	$ 21,427	$ 30,261

Warrant - Additional Informatio

Warrant - Additional Information (Details) - Janssen Agreement - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2017	Feb. 28, 2017
Class Of Warrant Or Right [Line Items]
Warrant to purchase common stock, shares		509,611
Exercise price		$ 9.81
Fair value of warrant at issuance	$ 3.4
Warrant expiration date	Feb. 9, 2022

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	Feb. 21, 2017	Dec. 23, 2013	May 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	May 01, 2016	Feb. 28, 2014
Class of Stock [Line Items]
Common stock, shares authorized				175,000,000		175,000,000		175,000,000
Common stock, par value				$ 0.00001		$ 0.00001		$ 0.00001
Common stock, shares issued				47,238,001		47,238,001		38,615,709
Common stock, shares outstanding				47,238,001		47,238,001		38,615,709
Preferred stock, shares authorized				25,000,000		25,000,000		25,000,000
Preferred stock, par value				$ 0.00001		$ 0.00001		$ 0.00001
Preferred stock, shares issued				0		0		0
Preferred stock, shares outstanding				0		0		0
Common stock, shares reserved for future issuance				6,636,779		6,636,779		5,268,127
Stock-based compensation expense				$ 2,153,000	$ 1,628,000	$ 10,087,000	$ 4,101,000
Restricted Stock Units
Class of Stock [Line Items]
Granted shares of restricted stock	423,650
Vesting periods						3 years
Stock-based compensation expense				407,000	232,000	$ 1,458,000	496,000
Total compensation cost to be recognized				2,900,000		$ 2,900,000
Restricted Stock Units | Share Based Compensation Award Tranche One
Class of Stock [Line Items]
Vesting percentage						100.00%
Stock Options
Class of Stock [Line Items]
Shares issued	719,400
Stock-based compensation description						Options granted by the Company vest over periods of between 12 and 48 months, subject, in each case, to the individual’s continued service through the applicable vesting date. Options vest in installments of (i) 25% at the one year anniversary and (ii) in either 36 or 48 equal monthly or 12 equal quarterly installments beginning in the thirteenth month after the initial vesting commencement date or grant date, subject to the individual’s continuous service with the Company.
Options expiration after the date of grant						10 years
Stock-based compensation expense				1,606,000	1,229,000	$ 4,927,000	3,378,000
Stock Options | Minimum
Class of Stock [Line Items]
Vesting periods						12 months
Stock Options | Maximum
Class of Stock [Line Items]
Vesting periods						48 months
Stock Options | Share Based Compensation Award Tranche One
Class of Stock [Line Items]
Vesting percentage						25.00%
Restricted Stock
Class of Stock [Line Items]
Vesting periods		1 year
Stock-based compensation expense				93,000	135,000	$ 158,000	148,000
Granted, Weighted-Average Grant Date Fair Value		$ 7.42
Restricted stock requisite service period description						The awards of restricted stock contained a performance condition wherein vesting is contingent upon the Company’s consummation of a liquidity event, as defined, prior to the fifth anniversary of the date of grant. Certain of the awards of restricted stock have a requisite service period that was complete upon grant. The remainder of the awards of restricted stock have a requisite service period of four years whereby the award vests 25% on the one year anniversary of the Vesting Commencement Date (as defined), then ratably on the first day of each calendar quarter for 12 quarters, subject to continuous service by the individual and achievement of the performance target.
Grant-date fair value of restricted stock issued		$ 3,900,000
Award requisite service period		4 years
Restricted Stock | Share Based Compensation Award Tranche One
Class of Stock [Line Items]
Vesting percentage		25.00%
Restricted Stock | Employees
Class of Stock [Line Items]
Granted shares of restricted stock		450,224
Restricted Stock | Non Employees
Class of Stock [Line Items]
Granted shares of restricted stock		79,067
Stock-based compensation expense				$ 100,000	100,000	$ 200,000	100,000
2014 Plans
Class of Stock [Line Items]
Common stock, shares reserved for future issuance				1,003,137		1,003,137		885,328		1,785,000
Incremental rate at which the shares reserved for issuance increase						3.00%
2014 Plans | Employees
Class of Stock [Line Items]
Granted, Shares						1,124,400
2014 Plans | Director
Class of Stock [Line Items]
Granted, Shares						87,500
2014 Plans | Inducement Award Program
Class of Stock [Line Items]
Common stock, shares reserved for future issuance									350,000
Granted, Shares			255,000
2014 Plans | Inducement Award Program | Employees
Class of Stock [Line Items]
Granted, Shares						405,000
2014 Plans | Restricted Stock Units | Employees
Class of Stock [Line Items]
Granted shares of restricted stock						439,900
2014 Employee Stock Purchase Plan
Class of Stock [Line Items]
Maximum shares of common stock authorized to be issued				262,500		262,500
Percentage of increase on common stock authorized on each anniversary						1.00%
Number of common stock outstanding						739,611
Common stock shares authorized percentage under the plan						5.00%
Purchase price at the end of offering period						85.00%
Offering period						6 months
Shares issued						44,789
Stock-based compensation expense				$ 47,000	$ 32,000	$ 100,000	$ 100,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Reserved Shares of Common Stock for Future Issuance (Details) - shares	Sep. 30, 2017	Dec. 31, 2016	Feb. 28, 2014
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	6,636,779	5,268,127
Stock Options and Restricted Stock Units
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	4,471,741	3,579,694
2014 Plans
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	1,003,137	885,328	1,785,000
Warrant To Purchase Common Stock
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	509,611
Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	652,290	803,105

Stockholders' Equity - Summar38

Stockholders' Equity - Summary of Reserved Shares of Common Stock for Future Issuance (Parenthetical) (Details) - shares	Jan. 01, 2017	Feb. 28, 2016	Jan. 01, 2016
2014 Plans
Class of Stock [Line Items]
Increase in common stock, shares reserved for future issuance	1,265,863		986,800
Employee Stock Purchase Plan
Class of Stock [Line Items]
Increase in common stock, shares reserved for future issuance		273,404

Stockholders Equity - Stock-Bas

Stockholders Equity - Stock-Based Compensation Expense Related to Share-Based Awards (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 2,153	$ 1,628	$ 10,087	$ 4,101
Research and Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	569	636	5,741	1,393
General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,584	$ 992	$ 4,346	$ 2,708

Stockholders Equity - Schedule

Stockholders Equity - Schedule of Compensation Expense by Type of Award (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 2,153	$ 1,628	$ 10,087	$ 4,101
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,606	1,229	4,927	3,378
Restricted Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	93	135	158	148
Restricted Stock Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	407	232	1,458	496
Employee Stock Purchase Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 47	$ 32	131	$ 79
Warrants
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense			$ 3,413

Stockholders Equity - Schedul41

Stockholders Equity - Schedule of Compensation Expense by Type of Award (Parenthetical) (Details) $ in Millions	Sep. 30, 2017USD ($)
Janssen Agreement
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Fair value related to warrants	$ 3.4

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income tax provisions or benefits	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017USD ($)ft²Extension_Option	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)ft²Extension_Option	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)	Oct. 31, 2017USD ($)	Jul. 31, 2016ft²
Commitments And Contingencies [Line Items]
Area of property leased | ft²	3,384		3,384				45,362
Monthly lease payments			$ 242,000
Operating lease payments commencement date			Jan. 1, 2017
Landlord contributions accounted for deferred lease incentive	$ 2,169,920		$ 2,169,920
Landlord contribution for leasehold improvements	70,526		$ 70,526
Sublease term			2 years
Frequency of sublease rent receivable			monthly
Sublease monthly rent receivable			$ 22,000
Operating lease obligations partially offset by receipt of future sublease payments	321,000		$ 321,000
Term for security deposit from execution of sublease			30 days
Rent expense associated with lease	800,000	$ 600,000	$ 2,400,000	$ 1,700,000
Contract cost incurred in research and development activities			43,800,000		$ 24,900,000
Total remaining contract costs	$ 293,800,000		$ 293,800,000
FibroGen, Inc. | Minimum
Commitments And Contingencies [Line Items]
Expected appeal process period			2 years
FibroGen, Inc. | Maximum
Commitments And Contingencies [Line Items]
Expected appeal process period			3 years
Subsequent Event
Commitments And Contingencies [Line Items]
Additional contract costs						$ 32,900,000
Office Space
Commitments And Contingencies [Line Items]
Lease expiration date			Sep. 11, 2026
Lease period, number of extension options | Extension_Option	1		1
Lease extension period			5 years
Lab Space
Commitments And Contingencies [Line Items]
Lease period, number of extension options | Extension_Option	1		1
Lease extension period			2 years
Lease period			5 years
Office Equipment One
Commitments And Contingencies [Line Items]
Capital leases term			3 years
Capital lease commencement period			2014-02
Office Equipment Two
Commitments And Contingencies [Line Items]
Capital leases term			3 years
Capital lease commencement period			2015-04
Office Equipment Three
Commitments And Contingencies [Line Items]
Capital leases term			3 years
Capital lease commencement period			2016-02
Other Assets
Commitments And Contingencies [Line Items]
Total security deposit in connection with lease	$ 1,280,857		$ 1,280,857		$ 1,280,857
Other Current Assets
Commitments And Contingencies [Line Items]
Total security deposit in connection with lease	21,432		21,432
Other Liabilities
Commitments And Contingencies [Line Items]
Total security deposit liability in connection with sublease	$ 21,432		21,432
Lease Monthly Payments On Or About January 1 2017
Commitments And Contingencies [Line Items]
Monthly lease payments			$ 22,000

Commitments and Contingencies44

Commitments and Contingencies - Schedule of Future Minimum Payments Required Under Leases (Details) $ in Thousands	Sep. 30, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
Operating Lease, 2017	$ 886
Operating Lease, 2018	3,545
Operating Lease, 2019	3,545
Operating Lease, 2020	3,545
Operating Lease, 2021	3,510
Operating Lease, Thereafter	14,666
Operating Lease, Total	29,697
Lease Payments to be Received from Sublease, 2017	64
Lease Payments to be Received from Sublease, 2018	257
Lease Payments to be Received from Sublease, Total	321
Net Operating Lease Payments, 2017	822
Net Operating Lease Payments, 2018	3,288
Net Operating Lease Payments, 2019	3,545
Net Operating Lease Payments, 2020	3,545
Net Operating Lease Payments, 2021	3,510
Net Operating Lease Payments, Thereafter	14,666
Net Operating Lease Payments, Total	29,376
Capital Lease, 2017	2
Capital Lease, 2018	5
Capital Lease, Total	7
Capital Lease, Present value of minimum lease payments at June 30, 2017	7
Net Operating Lease Payments and Capital Lease, 2017	824
Net Operating Lease Payments and Capital Lease, 2018	3,293
Net Operating Lease Payments and Capital Lease, 2019	3,545
Net Operating Lease Payments and Capital Lease, 2020	3,545
Net Operating Lease Payments and Capital Lease, 2021	3,510
Net Operating Lease Payments and Capital Lease, Thereafter	14,666
Net Operating Lease Payments and Capital Lease, Total	$ 29,383

Employee Retirement Plan - Addi

Employee Retirement Plan - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Compensation And Retirement Disclosure [Abstract]
Employers contributions to defined contribution plan	$ 27,000	$ 21,000	$ 200,000	$ 100,000
Employees eligibility age to participate in retirement plan			21 years

Net Loss per Share - Anti-Dilut

Net Loss per Share - Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share (Details) - shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	4,995,334	3,549,288
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	509,611
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	3,743,303	2,977,986
Unvested Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	13,982	132,739
Unvested Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	728,438	438,563