Ardelyx (ARDX) 10-K 17 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 10, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	ARDX
Entity Registrant Name	Ardelyx, Inc.
Entity Central Index Key	1,437,402
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		47,327,610
Entity Public Float			$ 197,442,141

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 74,598	$ 107,004
Short-term investments	126,225
Prepaid expenses and other current assets	3,169	5,027
Total current assets	203,992	112,031
Property and equipment, net	8,991	4,711
Other assets	148	104
Restricted cash		100
Total assets	213,131	116,946
Current liabilities:
Accounts payable	5,635	2,777
Accrued compensation and benefits	3,161	2,366
Accrued and other liabilities	10,405	2,580
Total current liabilities	19,201	7,723
Other long-term liabilities	779	322
Total liabilities	19,980	8,045
Commitments and contingencies (Note 14)
Stockholders' equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized as of December 31, 2016 and December 31, 2015, respectively; no shares issued and outstanding as of December 31, 2016 and December 31, 2015, respectively.
Common stock, $0.0001 par value; 300,000,000 shares authorized as of December 31, 2016 and December 31, 2015, respectively; 47,309,422 and 25,964,886 shares issued and outstanding as of December 31, 2016 and December 31, 2015, respectively.	5	3
Additional paid-in capital	407,092	210,386
Accumulated deficit	(213,875)	(101,488)
Accumulated other comprehensive loss	(71)
Total stockholders' equity	193,151	108,901
Total liabilities and stockholders' equity	$ 213,131	$ 116,946

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	47,309,422	25,964,886
Common stock, shares outstanding	47,309,422	25,964,886

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Licensing revenue		$ 21,611	$ 18,394
Collaborative development revenue		2,415	13,229
Total revenue		24,026	31,623
Operating expenses:
Research and development	$ 94,161	39,885	25,900
General and administrative	18,734	13,530	7,287
Total operating expenses	112,895	53,415	33,187
Loss from operations	(112,895)	(29,389)	(1,564)
Other income (expense), net	508	(261)	10
Change in fair value of preferred stock warrant liability			(1,593)
Loss before provision for income taxes	(112,387)	(29,650)	(3,147)
Benefit from (Provision for) income taxes		29	(67)
Net loss	$ (112,387)	$ (29,621)	$ (3,214)
Net loss per common share, basic and diluted	$ (2.80)	$ (1.29)	$ (0.31)
Weighted-average number of common shares used in net loss per share, basic and diluted	40,118,522	22,892,640	10,248,337

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (112,387)	$ (29,621)	$ (3,214)
Unrealized loss on available-for-sale securities, net of tax	(71)
Comprehensive loss	$ (112,458)	$ (29,621)	$ (3,214)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	IPO [Member]	Private Placement [Member]	Public Offering [Member]	Private Investment in Public Equity (PIPE) [Member]	Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member]Restricted Stock Units (RSUs) [Member]	Common Stock [Member]IPO [Member]	Common Stock [Member]Private Placement [Member]	Common Stock [Member]Public Offering [Member]	Common Stock [Member]Private Investment in Public Equity (PIPE) [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]IPO [Member]	Additional Paid-in Capital [Member]Private Placement [Member]	Additional Paid-in Capital [Member]Public Offering [Member]	Additional Paid-in Capital [Member]Private Investment in Public Equity (PIPE) [Member]	Accumulated Deficit [Member]	Other Comprehensive Income (Loss) [Member]
Balance, amount at Dec. 31, 2013						$ 56,155
Issuance of common stock, value		$ 61,241							$ 1					$ 61,240
Balance, amount at Dec. 31, 2013	$ (63,479)												$ 5,174					$ (68,653)
Issuance of common stock, shares									4,928,900
Balance, shares at Dec. 31, 2013						11,517,222
Balance, shares at Dec. 31, 2013							1,225,481
Conversion of convertible preferred stock to common stock in connection with initial public offering, amount	56,155					$ (56,155)	$ 1						56,154
Conversion of convertible preferred stock to common stock in connection with initial public offering, shares						(11,517,222)	11,517,222
Net exercise and conversion of preferred stock warrants to common stock in connection with initial public offering, amount	8,049												8,049
Net exercise and conversion of preferred stock warrants to common stock in connection with initial public offering, shares							571,244
Exercise of stock options and vesting of early exercised stock options, net of repurchases, amount	$ 238												238
Exercise of stock options and vesting of early exercised stock options, net of repurchases, shares	336,398						336,398
Issuance of common stock for services, amount	$ 208												208
Issuance of common stock for services, shares	10,000						10,000
Stock-based compensation	$ 1,484												1,484
Net loss	(3,214)																	(3,214)
Balance, amount at Dec. 31, 2014	60,682						$ 2						132,547					(71,867)
Balance, shares at Dec. 31, 2014							18,589,245
Issuance of common stock, value			$ 74,323							$ 1					$ 74,322
Issuance of common stock, shares										7,242,992
Issuance of common stock under employee stock purchase plan ,amount	548												548
Issuance of common stock under employee stock purchase plan , shares							41,580
Exercise of stock options and vesting of early exercised stock options, net of repurchases, amount	$ 111												111
Exercise of stock options and vesting of early exercised stock options, net of repurchases, shares	77,784						77,784
Issuance of common stock for services, amount	$ 194												194
Issuance of common stock for services, shares	13,285						13,285
Stock-based compensation	$ 2,634												2,634
Other	30												30
Net loss	(29,621)																	(29,621)
Balance, amount at Dec. 31, 2015	108,901						$ 3						210,386					(101,488)
Balance, shares at Dec. 31, 2015							25,964,886
Issuance of common stock, value				$ 80,837	$ 109,736						$ 1	$ 1				$ 80,836	$ 109,735
Issuance of common stock, shares								5,000			8,625,000	12,600,230
Issuance of common stock under employee stock purchase plan ,amount	$ 576												576
Balance, shares at Dec. 31, 2015	25,964,886
Issuance of common stock under employee stock purchase plan , shares							69,054
Exercise of stock options and vesting of early exercised stock options, net of repurchases, amount	$ 55												55
Exercise of stock options and vesting of early exercised stock options, net of repurchases, shares	25,134						25,134
Issuance of common stock for services, amount	$ 187												187
Issuance of common stock for services, shares	20,118						20,118
Stock-based compensation	$ 5,317												5,317
Other comprehensive loss	(71)																		$ (71)
Net loss	(112,387)																	(112,387)
Balance, amount at Dec. 31, 2016	$ 193,151						$ 5						$ 407,092					$ (213,875)	$ (71)
Balance, shares at Dec. 31, 2016							47,309,422

Consolidated Statements of Con7

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Private Placement [Member]
Stock issuance costs		$ 3,449
Public Offering [Member]
Stock issuance costs	$ 5,413
Private Investment in Public Equity (PIPE) [Member]
Stock issuance costs	$ 263

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (112,387)	$ (29,621)	$ (3,214)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	1,295	829	302
Amortization of deferred financing costs	346	351
Amortization of deferred compensation for services	194	107
Amortization of premium on investment securities	(86)
Stock-based compensation	5,317	2,634	1,692
Change in fair value of preferred stock warrant liability			1,593
Loss from disposal of fixed assets		65
Changes in operating assets and liabilities:
Accounts receivable		2,584	3,852
Prepaid expenses and other assets	1,562	(4,083)	96
Accounts payable	2,148	(371)	831
Accrued compensation and benefits	795	718	721
Accrued and other liabilities	8,282	2,000	647
Deferred revenue		(47,053)	6,755
Other long-term liabilities			122
Net cash (used in) provided by operating activities	(92,534)	(71,840)	13,397
Investing activities
Purchases of short-term investments	(133,810)
Proceeds from maturities of short-term investments	7,600
Purchases of property and equipment	(4,866)	(3,454)	(1,856)
Net cash used in investing activities	(131,076)	(3,454)	(1,856)
Financing activities
Proceeds from issuance of common stock, net of issuance costs	190,573	74,323	61,241
Proceeds from issuance of common stock under stock plans	631	659	71
Other		30	(2)
Net cash provided by (used in) financing activities	191,204	75,012	61,310
Net increase in cash and cash equivalents	(32,406)	(282)	72,851
Cash and cash equivalents at beginning of period	107,004	107,286	34,435
Cash and cash equivalents at end of period	74,598	107,004	107,286
Supplementary disclosure of cash flow information
Income taxes paid		$ 69
Supplementary disclosure of non-cash financing information:
Acquisition of property and equipment included in accounts payable and accrued liabilities	730
Services settled through the issuance of common stock	$ 187		208
Reclassification of convertible preferred warrant liability to additional paid-in capital			8,049
Conversion of convertible preferred stock to common stock at closing of initial public offering			$ 56,155

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Organization and Basis of Presentation	1. ORGANIZATION AND BASIS OF PRESENTATION The Company is focused on enhancing the way patients with cardiorenal and gastrointestinal, or GI, diseases are treated by using the gut as the gateway to delivering medicines that matter. The Company has pioneered the development of small molecule therapeutics that act predominantly in the GI tract, thereby avoiding potentially negative side effects on the rest of the body. The Company’s strategy is to evolve from R&D-focused Cardiorenal Portfolio • Tenapanor: Phase 3 clinical development for treatment of ESRD patients on dialysis suffering from elevated phosphate, or hyperphosphatemia • RDX7675: Phase 3 clinical development for the treatment of patients with hyperkalemia, common in patients with CKD and/or heart failure • Research Programs: the Company is evaluating small-molecule approaches to treat hyperkalemia in order to significantly reduce pill burden as well as leveraging its knowledge of phosphorus absorption to discover improved approaches. Gastrointestinal Portfolio • Tenapanor: Phase 3 clinical development for treatment of IBS-C • RDX8940: IND filed in late 2016 to begin clinical studies. • Research Programs: The Company is leveraging our knowledge of the mechanisms of tenapanor in order to discover new agents that modulate transport of ions and other processes in the gut. The Company operates in only one business segment, which is the development of biopharmaceutical products.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying consolidated financial statements include the accounts of Ardelyx and its wholly-owned subsidiary, Ardelyx Cayman Islands, and have been prepared in accordance with U.S. generally accepted accounting principles (“US GAAP”). Intercompany transactions and balances have been eliminated in consolidation. Use of Estimates The preparation of consolidated financial statements in conformity with US GAAP requires management to make estimates and judgments that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue, clinical trial accruals, contract manufacturing accruals, fair value of assets and liabilities, income taxes, and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates. Liquidity The Company has never been profitable on an annual basis and, as of December 31, 2016, the Company has an accumulated deficit of $213.9 million. The Company has incurred net losses of approximately $112.4 million, $29.6 million and $3.2 million in the years ended December 31, 2016, 2015 and 2014, respectively. The Company expects to continue to incur net operating losses for the foreseeable future, as the Company continues the development of, seeks regulatory approval for, and if approved, begins to commercialize, tenapanor and RDX7675. The Company will need additional funding to support its future operating activities and adequate funding may not be available to the Company on acceptable terms, or at all. The Company’s failure to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the business, results of operations, and financial condition. The Company will need to generate significant revenues to achieve profitability and may never do so. Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original maturity date of 90 days or less on the date of purchase to be cash equivalents. Short-Term Investments Short-term investments consist of debt securities classified as available-for-sale available-for-sale available-for-sale Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and short-term investments. The Company is exposed to credit risks in the event of default by the issuers to the extent of the amount recorded in its Consolidated Balance Sheets. Cash, cash equivalents and short-term investments are invested through banks and other financial institutions in the United States. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized over the lesser of the estimated useful lives or the related remaining lease term. Impairment of Long-Lived Assets The carrying value of long-lived assets, including property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate that the asset may not be recoverable. An impairment loss is recognized when the total of estimated future undiscounted cash flows, expected to result from the use of the asset and its eventual disposition, are less than its carrying amount. Impairment, if any, would be assessed using discounted cash flows or other appropriate measures of fair value. Through December 31, 2016, there have been no such impairment losses. Income Taxes The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Revenue Recognition Revenue from research activities made under collaboration partnership agreements are recognized as the services are provided and when there is persuasive evidence that an arrangement exists, delivery has occurred, the price is fixed or determinable, and collectability is reasonably assured. Revenue generated from research and licensing agreements typically includes up-front For revenue agreements with multiple-element arrangements, such as license and development agreements, the Company allocates revenue to each unit of accounting based on the relative selling price of each unit. When applying the relative selling price method, the Company determines the selling price for each deliverable using vendor-specific objective evidence or third-party evidence. If neither exists, the Company uses its best estimate of selling price for that deliverable. Revenue allocated is then recognized when the four basic revenue recognition criteria are met for each deliverable. The Company recognizes revenue from upfront payments ratably over the term of its estimated period of performance under the agreement which is recorded as licensing revenue. Reimbursements for development costs incurred under the Company’s license agreement with AstraZeneca are classified as collaborative development revenue. The Company recognizes cost reimbursement revenue under collaboration partnership agreements as the related research and development costs for services are rendered. Deferred revenue represents the portion of research or license payments received which has not been earned. Revenues from milestones, if they are nonrefundable and deemed substantive, are recognized upon successful accomplishment of the milestones. To the extent that non-substantive non-substantive Research and Development Costs Research and development costs are charged to expense as incurred and consist of costs incurred to further the Company’s research and development activities including salaries and related employee benefits, costs associated with clinical trials, costs related to pre-commercialization Accrued Research and Development Expenses As part of the process of preparing our financial statements, the Company is required to estimate its accrued expenses. This process involves reviewing open contracts and purchase orders, communicating with its personnel to identify services that have been performed on its behalf and estimating the level of service performed and the associated cost incurred for the service when the Company has not yet been invoiced or otherwise notified of the actual cost. The majority of the Company’s service providers invoice its monthly invoices in arrears for services performed or when contractual milestones are met. The Company makes estimates of its accrued expenses as of each balance sheet date in its financial statements based on facts and circumstances known to the Company at that time. The Company periodically confirms the accuracy of its estimates with the service providers and make adjustments if necessary. Examples of estimated accrued research and development expenses include fees paid to: • CROs in connection with clinical studies; • investigative sites in connection with clinical studies; • vendors related to product manufacturing, development and distribution of clinical supplies; • collaborator entities in connection with our collaboration agreements; and • vendors in connection with preclinical development activities. The Company records expenses related to clinical studies and manufacturing development activities based on its estimates of the services received and efforts expended pursuant to contracts with multiple CROs and manufacturing vendors that conduct and manage these activities on its behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract, and may result in uneven payment flows. There may be instances in which payments made to the Company’s vendors will exceed the level of services provided and result in a prepayment of the expense. Payments under some of these contracts depend on factors such as the successful enrollment of subjects and the completion of clinical trial milestones. In accruing service fees, the Company estimates the time period over which services will be performed, enrollment of subjects, number of sites activated and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the Company’s estimate, the Company will adjust the accrued or prepaid expense balance accordingly. To date, there have been no material differences from the Company’s estimates to the amounts actually incurred. Stock-Based Compensation The Company recognizes compensation expense for all share-based payment awards made to employees and directors based on estimated fair values. For employee stock options, the Company determines the grant date fair value of the awards using the Black-Scholes option-pricing model and generally recognizes the fair value as stock-based compensation expense on a straight-line basis over the vesting period of the respective awards. Stock-based compensation expense is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company’s stock-based compensation is reduced for the estimated forfeitures at the date of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. For restricted stock, the compensation cost for these awards is based on the closing price of the Company’s common stock on the date of grant and recognized as compensation expense on a straight-line basis over the requisite service period. The Company accounts for equity instruments issued to nonemployees based on their fair values on the measurement dates using the Black-Scholes option-pricing model. The estimated fair values of the options granted to nonemployees are remeasured as they vest. As a result, the noncash charge to operations for nonemployee options with vesting conditions is affected each reporting period by changes in the fair value of the Company’s common stock. Convertible Preferred Stock Warrant Liability The Company accounted for freestanding warrants to purchase shares of convertible preferred stock that were contingently redeemable as liabilities in the balance sheets at their estimated fair value. Convertible preferred stock warrants were subject to remeasurement at each balance sheet date, and any change in fair value was recognized as a component of other expense, net in the statements of operations and comprehensive loss. The Company continued to adjust the carrying value of the warrants until the closing of its initial public offering (IPO), at which time the warrants were net exercised for shares of the Company’s common stock and the liability was reclassified to stockholders’ equity (deficit). Comprehensive Loss Comprehensive loss is composed of two components: net loss and other comprehensive loss. Other comprehensive loss refers to gains and losses that under GAAP are recorded as an element of stockholders’ equity (deficit), but are excluded from net loss. Net Loss per Share Basic net loss per common share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. Diluted net loss per common share in the periods presented is the same as basic net loss per common share, since the effects of potentially dilutive securities are antidilutive. Recent Accounting Pronouncements In May, 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers 2014-09”), 2014-09 2014-09, - Revenue from Contracts with Customers 2016-08 2016-10 2016-11 2014-09 2014-16 2016-12 In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements—Going Concern: Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern 2014-15”). 2014-15 2014-15 2014-15 In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) right-of-use 2016-02 2016-02 2016-02, In March 2016, the FASB issued Accounting Standards 2016-09, Improvements to Employee Share-Based Payment Accounting 2016-09 2016-09, In August 2016, the FASB issued Accounting Standards Update (ASU) 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments 2016-15 In November 2016, the FASB issued ASU 2016-18, Restricted Cash, 2016-08 2016-18 The Company has reviewed all other significant newly-issued accounting pronouncements and concluded that they either are not applicable to the Company’s operations or that no material effect is expected on its consolidated financial statements as a result of future adoption.

Cash, Cash Equivalents and Inve

Cash, Cash Equivalents and Investments	12 Months Ended
	Dec. 31, 2016
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Investments	3. CASH, CASH EQUIVALENTS AND INVESTMENTS Securities classified as cash and cash equivalents and short-term investments as of December 31, 2016 and December 31, 2015 are summarized below (in thousands). Estimated fair value is based on quoted market prices for these investments. December 31, 2016 Amortized Gross Unrealized Fair Value Gains Losses Cash and cash equivalents: Cash $ 3,638 $ — $ — $ 3,638 Money market funds 68,561 — — 68,561 Commercial paper 2,399 — — 2,399 Total cash and cash equivalents $ 74,598 $ — $ — $ 74,598 Short-term investments Corporate bonds 58,464 2 (56 ) $ 58,410 Commercial paper 62,946 5 (20 ) 62,931 Asset-backed securities 4,886 — (2 ) 4,884 Total short-term investments $ 126,296 $ 7 $ (78 ) $ 126,225 Total $ 200,894 $ 7 $ (78 ) $ 200,823 December 31, 2015 Amortized Gross Unrealized Fair Value Gains Losses Cash and cash equivalents: Cash $ 25,194 $ — $ — $ 25,194 Money market funds 81,810 — — 81,810 Total cash and cash equivalents $ 107,004 $ — $ — $ 107,004 During the three months ended December 31, 2016, the Company determined that one of its bank accounts comprising $24.0 million at December 31, 2015 should have been classified as cash rather than as money market funds. Accordingly, the impact of this reclassification has been reflected in the table for December 31, 2015 presented above. The Company made a similar reclassification in NOTE 4, FAIR VALUE MEASUREMENTS Cash equivalents consist of money market funds and corporate debt securities with original maturities of three months or less at the time of purchase, and the carrying amount is a reasonable approximation of fair value. The Company invests its cash in high quality securities of financial and commercial institutions. These securities are carried at fair value, which is based on readily available market information, with unrealized gains and losses included in “accumulated other comprehensive loss” within stockholders’ equity on the Company’s consolidated balance sheets. The Company uses the specific identification method to determine the amount of realized gains or losses on sales of marketable securities. For the year ended December 31, 2016, there were no realized gains or losses on the available-for-sale All available-for-sale non-current. available-for-sale available-for-sale

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. FAIR VALUE MEASUREMENTS Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The three-level hierarchy for the inputs to valuation techniques is briefly summarized as follows: Level 1 – Valuations are based on quoted prices in active markets for identical assets or liabilities. Examples of assets and liabilities utilizing Level 1 inputs are certain money market funds, U.S. Treasuries and trading securities with quoted prices on active markets. Level 2 – Valuations based on inputs other than the quoted prices in active markets that are observable either directly or indirectly in active markets. Examples of assets and liabilities utilizing Level 2 inputs are U.S. government agency bonds, corporate bonds, commercial paper, certificates of deposit and over-the-counter Level 3 – Valuations based on unobservable inputs in which there is little or no market data, which require us to develop our own assumptions. The following table sets forth the fair value of the Company’s financial assets measured on a recurring basis by level within the fair value hierarchy: December 31, 2016 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 68,561 $ 68,561 $ — $ — Corporate bonds 58,410 — 58,410 — Commercial paper 65,330 — 65,330 — Asset-backed securities 4,884 — 4,884 — Total $ 197,185 $ 68,561 $ 128,624 $ — December 31, 2015 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 81,810 $ 81,810 $ — $ — Certificates of deposit 100 — 100 — Total $ 81,910 $ 81,810 $ 100 $ — Where quoted prices are available in an active market, securities are classified as Level 1. The Company classifies money market funds as Level 1. When quoted market prices are not available for the specific security, then the Company estimates fair value by using benchmark yields, reported trades, broker/dealer quotes, and issuer spreads. The Company classifies certificates of deposit as Level 2. In certain cases, where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3. There were no transfers between Level 1 and Level 2 during the periods presented. The carrying amounts reflected in the balance sheets for cash equivalents, other receivables, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values at both December 31, 2016 and December 31, 2015, due to their short-term nature.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property and Equipment	5. PROPERTY AND EQUIPMENT Property and equipment consist of the following: December 31, 2016 2015 (in thousands) Laboratory equipment $ 5,487 $ 4,471 Office equipment and furniture 824 134 Leasehold improvements 7,783 3,914 Property and equipment, gross 14,094 8,519 Less: accumulated depreciation (5,103 ) (3,808 ) Total property and equipment, net $ 8,991 $ 4,711 Depreciation expense totaled $1.3 million, $0.8 million and $0.3 million for the years ended December 31, 2016, 2015 and 2014.

Accrued and Other Liabilities

Accrued and Other Liabilities	12 Months Ended
	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued and Other Liabilities	6. ACCRUED AND OTHER LIABILITIES Accrued liabilities and other liabilities consist of the following (in thousands): December 31, 2016 2015 Accrued clinical trial expenses $ 6,694 $ 311 Accrued contract manufacturing 2,705 289 Accrued professional and consulting services 322 272 AstraZeneca clinical trial material accrual — 1,328 Other 684 380 $ 10,405 $ 2,580

Collaboration and Licensing Agr

Collaboration and Licensing Agreements	12 Months Ended
	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration and Licensing Agreements	7. COLLABORATION AND LICENSING AGREEMENTS AstraZeneca AB (“AstraZeneca”) In October 2012, the Company entered into a collaboration partnership with AstraZeneca for the worldwide development and commercialization of tenapanor. Under the terms of the AstraZeneca collaboration partnership agreement, or the AstraZeneca Agreement, the Company received an aggregate of $75 million in up-front In June 2015, the Company entered into a termination agreement with AstraZeneca (the “Termination Agreement”) pursuant to which all licenses granted to AstraZeneca to the Company’s portfolio of NHE3 inhibitors, including the Company’s lead product candidate, tenapanor, were terminated, except for the limited purpose of allowing AstraZeneca to satisfy its obligations under the Termination Agreement. As the AstraZeneca Agreement was terminated in June 2015, the Company recognized the remaining deferred revenue balance of $43.1 million during the three months ended June 30, 2015. In the three months ended June 30, 2015, the Company recorded a $15.0 million payment for the return of the licenses as well as a $10.0 million payment for reimbursement of research and development expenses and the acceleration of the transfer of information and materials as a reduction in licensing revenue in the consolidated statements of operations. There has been no recognition of licensing revenue or collaborative development revenue since the termination of the AstraZeneca agreement in 2015. Sanofi SA (“Sanofi”) In February 2014, the Company entered into a license option and license agreement with Sanofi (the “Sanofi Agreement”) for its phosphate transport NaP2b inhibitor program. Under the terms of the Sanofi Agreement, the Company granted Sanofi an exclusive worldwide license to conduct research utilizing the Company’s small molecule NaP2b inhibitors. In addition, Sanofi had the option to obtain an exclusive license to develop, manufacture and commercialize potential products under the agreement. Under the Sanofi Agreement, the Company received a payment of $1.25 million in March 2014, which was fully recognized as licensing revenue in May 2014 after the Company completed its obligation to provide to Sanofi the background know-how, The Sanofi Agreement was terminated effective September 30, 2015 and all rights were returned to the Company. There was no payment associated with termination and the return of rights to the Company.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2016
Text Block [Abstract]
Convertible Preferred Stock	8. CONVERTIBLE PREFERRED STOCK On June 24, 2014, prior to the closing of the IPO, all outstanding shares of convertible preferred stock converted into 11,517,222 shares of common stock with the related carrying value of $56.2 million reclassified to common stock and additional paid-in

Preferred Stock Warrants

Preferred Stock Warrants	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Preferred Stock Warrants	9. PREFERRED STOCK WARRANTS In connection with the closing of the Series B financing in August 2011, the Company issued warrants for the purchase of 574,953 shares of Series B convertible preferred stock. The exercise price of the warrants was $0.09 per share. The preferred stock warrant liability was measured at fair value on a recurring basis. Changes in fair value were recorded in change in fair value of preferred stock warrant liability in the Statements of Operations and Comprehensive Loss. As of December 31, 2013, the fair value of this convertible preferred stock warrant liability amounted to $6.5 million. Just prior to the IPO close date of June 24, 2014, the preferred stock warrant liability was remeasured prior to the net exercise of the warrants using the IPO price. The preferred stock warrants were net exercised upon the completion of our initial public offering (IPO) in June 2014 and were reclassified to stockholder’s equity.

Equity Incentive Plans

Equity Incentive Plans	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Incentive Plans	10. EQUITY INCENTIVE PLANS 2008 Plan The Company granted options under its 2008 Stock Incentive Plan (the “2008 Plan”) until June 2014 when it was terminated as to future awards, although it continues to govern the terms of options that remain outstanding under the 2008 Plan. The 2008 Plan provided for the granting of incentive and nonstatutory stock options, and stock purchase rights to employees, directors and consultants at the discretion of the Board of Directors. Stock options granted generally vest over a period of four years from the date of grant. In connection with the Board of Directors and stockholders’ approval of the 2014 Plan, all remaining shares available for future award under the 2008 Plan were transferred to 2014 Plan, and the 2008 Plan was terminated. 2014 Plan The 2014 Equity Incentive Award Plan (“2014 Plan”) became effective on June 18, 2014, immediately prior to the time the Company’s Registration Statement on Form S-1 2016 Plan In November 2016, the Company’s board of directors approved the 2016 Employment Commencement Incentive Plan (the Inducement Plan) under which 1,000,000 shares were reserved. As of December 31, 2016, no shares of the Company’s common stock were subject to inducement grants that were issued pursuant to the Inducement Plan. Stock Plan Activity The following table summarizes activity under the 2008 Plan, the 2014 Plan, and the Inducement Plan, including grants to nonemployees issued: Options Issued and Outstanding Shares Available for Grant Number of Shares Weighted-Average Price per Share Aggregate Intrinsic Value (in thousands) Balance at December 31, 2013 3,914 1,162,829 $ 1.03 Options authorized 1,452,661 — — Options granted (188,888 ) 188,888 24.41 Options exercised — (336,398 ) 0.71 Options canceled 4,084 (4,084 ) 2.21 Options repurchased 3,511 (3,511 ) 0.55 Issuance of common stock for services (10,000 ) — — Balance at December 31, 2014 1,265,282 1,007,724 $ 5.51 Options authorized 743,569 — Options granted (379,709 ) 379,709 19.60 Options exercised — (77,784 ) 1.42 Options canceled 28,563 (28,563 ) 12.41 Issuance of common stock for services (13,285 ) — — Balance at December 31, 2015 1,644,420 1,281,086 $ 9.78 Options authorized 1,038,595 — Additional shares reserved under the Inducement Plan 1,000,000 — — Options granted (1,524,014 ) 1,524,014 11.42 Options exercised — (25,134 ) 2.19 Options canceled 67,743 (67,743 ) 16.67 Issuance of common stock for services (20,118 ) — — Balance at December 31, 2016 2,206,626 2,712,223 $ 10.60 $ 13,750 Vested and expected to vest at December 31, 2016 2,640,905 $ 10.54 $ 13,574 Vested at December 31, 2016 1,263,430 $ 7.58 $ 10,187 The weighted-average grant-date estimated fair value of options granted during the years ended December 31, 2016, 2015 and 2014 was $7.69, $12.91 and $18.53 per share. The aggregate intrinsic value was calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s common stock of $14.20 per share as of December 31, 2016. The total estimated fair value of options that vested during the years ended December 31, 2016, 2015 and 2014 was $6.4 million, $2.4 million and $0.5 million, respectively. Restricted Stock Units During 2016, the Compensation Committee made awards of RSUs to certain employees of the Company. The RSUs awarded under the Plan are generally subject to ratable vesting and are contingent on such employee’s continued service on such date. RSUs are generally subject to forfeiture if employment terminates prior to the release of vesting restrictions. The Company expenses the cost of the RSUs, which is determined to be the fair market value of the shares of common stock underlying the RSUs at the date of grant, ratably over the period during which the vesting restrictions lapse. A summary of non-vested Number of Shares Weighted-Average Non-vested 9,425 $ 18.04 Granted 174,389 14.34 Vested (30,122 ) 16.35 Forfieted (5,000 ) 18.04 Non-vested 148,692 $ 14.17 The total estimated fair value of restricted stock vested during 2016 was $0.5 million. Employee Stock Purchase Plan The Company adopted the 2014 Employee Stock Purchase Plan (ESPP) and initially reserved 202,762 shares of common stock as of its effective date of June 18, 2014. If approved by the Administrator of the ESPP, on the first day of each calendar year, ending in 2024, the number of shares in the reserve will increase by an amount equal to the lesser of (i) one percent (1.0%) of the shares of common stock outstanding on the last day of the immediately preceding fiscal year and (ii) such number of shares of common stock as determined by the board of directors; provided, however, no more than 2,230,374 shares of our common stock may be issued under the ESPP. Effective January 1, 2015, the ESPP share reserve was increased by 185,892. Under the ESPP, participants are offered the option to purchase shares of the Company’s common stock at a discount during a series of successive offering periods normally commencing on March 1 and September 1 of each year. The initial offering period commenced on September 1, 2014 and will end on February 27, 2015. As of December 31, 2016 278,020 shares were available for future issuance under the ESPP. The following table illustrates the weighted-average assumptions for the Black-Scholes option-pricing model used in determining the fair value of ESPP purchase rights granted to employees: Year Ended December 31, 2016 2016 2015 Expected term ( years) 0.5 0.5 Volatility 76 % 97 % Risk-free interest rate 0.48 % 0.16 % Dividend yield — % — % There were no shares issued during the year ended December 31, 2014 under the ESPP. In 2015, the Company sold 41,580 shares of its common stock under the ESPP. The shares were purchased at a weighted- average purchase price of $13.25 with proceeds of approximately $0.6 million. In 2016, the Company sold 69,054 shares of its common stock under the ESPP. The shares were purchased at a weighted-average purchase price of $8.34 with proceeds of approximately $0.6 million. Modification of Stock Awards During September 2014, the Company entered into a Transition and Separation Agreement with its Chief Scientific Officer, Dominique Charmot, under which certain restricted shares that were subject to vesting and repurchase by the Company have become fully vested as of Dr. Charmot’s separation from the Company as an employee and director on December 23, 2014. This resulted in the acceleration of the vesting for 58,969 shares of restricted stock. As a result of the acceleration, the Company has recorded a stock-based compensation charge of $0.8 million during the year ended December 31, 2014 to reflect the revised service period for the restricted stock and related vesting of shares that would otherwise not have vested. Offering of Common Stock and Warrants In June 2015, the Company sold and issued an aggregate of 7,242,992 shares of its common stock and warrants to purchase 2,172,899 shares of common stock for aggregate gross proceeds of approximately $77.8 million or net proceeds, after deducting issuance costs, of approximately $74.3 million. The purchase price for the common stock was $10.70 per share and the purchase price for the warrants was $0.125 per warrant. The warrants are exercisable for an exercise price of $13.91 per share at any time prior to the earlier of (i) 5 years from the date of issuance or (ii) certain changes in control of the Company. The Company has determined that the warrants should be classified as equity. In July 2015, the Company filed a registration statement with the SEC with respect to the common stock and warrants. Other than with respect to warrants issued to holders affiliated with New Enterprise Associates, the warrants contain limitations that prevent each holder of warrants from acquiring shares upon exercise of the warrants that would cause the number of shares beneficially owned by it and its affiliates to exceed 9.99% of the total number of shares of the Company’s common stock then issued and outstanding. In addition, upon certain changes in control of the Company, each holder of a warrant can elect to receive, subject to certain limitations and assumptions, securities in a successor entity. None of the warrants issued in June 2015 have been exercised during each of the years ended December 31, 2015 and December 31, 2016. Stock-based Compensation Total stock-based compensation recognized was as follows (in thousands): Year Ended December 31, 2016 2015 2014 (in thousands) Research and development $ 2,786 $ 1,327 $ 1,376 General and administrative 2,531 1,307 316 Total stock-based compensation $ 5,317 $ 2,634 $ 1,692 As of December 31, 2016, the Company had $11.5 million, $2.1 million and $0.1 million of total unrecognized compensation expense, net of estimated forfeitures, related to stock option grants, restricted stock unit grants and ESPP, respectively, that will be recognized over an average vesting period of 2.9 years, 3.5 years and 0.2 years, respectively. The estimated grant date fair value of employee stock options was calculated using the Black-Scholes option-pricing model, based on the following weighted assumptions: Year Ended December 31, 2016 2015 2014 Expected term ( years) 5.99 5.89 5.97 Volatility 77 % 75 % 94 % Risk-free interest rate 1.62 % 1.64 % 1.79 % Dividend yield — % — % — % Expected Term Expected Volatility comparable Risk-Free Interest Rate zero-coupon Expected Dividend Options Granted to Nonemployees. The Company has granted options to purchase shares of common stock to consultants in exchange for services performed. The Company granted options to purchase 12,500, 5,000 and 10,000 shares with average exercise prices of $13.71, $18.58 and $20.77 per share, respectively, during the years ended December 31, 2016, 2015 and 2014, respectively. These options vest upon grant or various terms up to three years. The Company recognized non-employee non-employee Issuance of Common Stock for Services During the year ended December 31, 2016, the Company issued 20,118 shares of common stock in exchange for services performed. The shares issued were valued at $0.2 million based on the fair value of the common stock on the date of grant. During the year ended December 31, 2015, the Company issued 13,285 shares of common stock in exchange for services performed. The shares issued were valued at $0.2 million based on the fair value of the common stock on the date of grant. During the year ended December 31, 2014, the Company issued 10,000 shares of common stock in exchange for services performed. The shares issued were valued at $0.2 million based on the fair value of the common stock on the date of grant.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	11. INCOME TAXES The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate: December 31, 2016 2015 2014 Expected income tax provision at the federal statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit 0.3 (3.8 ) 4.6 Change in valuation allowance (36.2 ) (30.7 ) (17.9 ) Nondeductible expenses — — (20.6 ) Tax credits 0.3 1.3 — Other 0.6 (1.7 ) (3.2 ) Income tax provision 0.0 % 0.1 % (2.1 %) Significant components of the Company’s deferred tax assets are as follows: December 31, 2016 2015 (in thousands) Deferred tax assets: Net operating loss carryforwards $ 68,639 $ 30,572 Research credits 2,643 1,919 Stock awards 2,583 1,011 Other 1,558 571 Gross deferred tax assets 75,423 34,073 Valuation allowance (74,520 ) (33,845 ) Total deferred tax assets 903 228 Deferred tax liabilities (903 ) (228 ) Net deferred tax assets $ — $ — The Company assesses the available positive and negative evidence to estimate whether sufficient future taxable income will be generated to permit use of the existing deferred tax assets. A significant piece of objective negative evidence evaluated was the cumulative loss incurred over the two-year At December 31, 2016, the Company had net operating loss carryforwards for federal income tax purposes of approximately $192.0 million that expire beginning in 2030 if not utilized, and federal research and development tax credit carryforwards of approximately $3.4 million that expire beginning in 2027 if not utilized. In addition, the Company had net operating loss carryforwards for California income tax purposes of approximately $31.1 million that expire beginning of 2030 if not utilized, and state research and development tax credit carryforwards of approximately $3.8 million which can be carried forward indefinitely. The Company had other state net operating losses of approximately $1.1 million that begin to expire in 2025. The Company had approximately insignificant and $0.2 million of minimum tax credit carryovers for federal and California income tax purposes, respectively. The minimum tax credits have no expiration date. The future utilization of the net operating loss and tax credit carryforwards and credits may be subject to an annual limitation, pursuant to Internal Revenue Code Sections 382 and 383, as a result of ownership changes that may have occurred previously or that could occur in the future. Due to the existence of the valuation allowance, future changes under Sections 382 and 383 will not impact the Company’s effective tax rate. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: December 31, 2016 2015 2014 (in thousands) Balance at beginning of year $ 3,298 $ 2,815 $ 1,411 Additions (subtractions) based on tax positions related to prior year 45 (58 ) 405 Additions based on tax positions related to current year 549 541 999 Balance at end of year $ 3,892 $ 3,298 $ 2,815 The unrecognized tax benefits, if recognized and in absence of full valuation allowance, would impact the income tax provision by $3.9 million, $3.3 million and $2.8 million as of December 31, 2016, 2015 and 2014, respectively. The Company has elected to include interest and penalties as a component of tax expense. During the years ended December 31, 2016, 2015 and 2014, the Company did not recognize accrued interest and penalties related to unrecognized tax benefits. Although the timing and outcome of an income tax audit is highly uncertain, the Company does not anticipate that the amount of existing unrecognized tax benefits will significantly change during the next 12 months. The Company files income tax returns in the U.S. federal, California, Maryland, Massachusetts, New Hampshire and New Jersey, tax jurisdictions. Due to the Company’s net operating loss and tax credit carryforwards, the income tax returns remain open to U.S. federal and California state tax examinations. The Company is not currently under examination in any tax jurisdiction.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Net Loss Per Share	12. NET LOSS PER SHARE Basic net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, less shares subject to repurchase, and excludes any dilutive effects of share-based awards and warrants. Diluted net loss per common share is computed giving effect to all potential dilutive common shares, including common stock issuable upon exercise of stock options, and unvested restricted common stock and stock units. As the Company had net losses for the years ended December 31, 2016, 2015 and 2014, all potential common shares were determined to be anti-dilutive. The following table sets forth the computation of net loss per common share (in thousands, except share and per share amounts): December 31, 2016 2015 2014 Numerator: Net loss $ (112,387 ) $ (29,621 ) $ (3,214 ) Denominator: Weighted average number of shares outstanding—basic and diluted 40,118,522 22,892,640 10,248,337 Net loss per share-basic and diluted $ (2.80 ) $ (1.29 ) $ (0.31 ) Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: December 31, 2016 2015 2014 Options to purchase common stock 2,557,314 1,244,442 1,007,724 Warrants to purchase common stock 2,172,899 300,302 — Total 4,730,213 1,544,744 1,007,724

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2016
Spouse of Executive Officer [Member] | Clinical Operations Consulting Arrangement [Member]
Related Party Transactions	13. RELATED PARTY TRANSACTIONS There were no related party transactions in 2016 and 2015. As part of the consulting arrangement with the spouse of an executive of the Company to provide research and development services related to clinical operations, the Company incurred expenses of $0.2 million for services rendered during year ended December 31, 2014.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	14. COMMITMENTS AND CONTINGENCIES The Company has a lease agreement for a facility in Fremont, California that was amended in December 2012 to extend the lease agreement to September 2016. In September 2014, the Company signed the second amendment to its facility lease agreement in Fremont, California to add space and to extend the lease term through September 2019. In addition, the amended lease agreement provides for a tenant improvement allowance of up to $0.6 million. In May 2016, the Company signed a third amendment to its facility lease agreement in Fremont, California to add space and to extend the lease term through September 2021 (the “Third Amendment”). The Third Amendment provides for a tenant improvement allowance of up to $0.4 million and the extended lease has rent escalation clauses throughout the lease term. Rent increases, including the impact of a rent holiday and leasehold improvement allowance from the landlord, will be recognized as deferred rent and amortized on a straight-line basis over the term of the lease. Under the terms of the lease agreement, the Company provided the lessor with a security deposit in the amount of $0.1 million. The lessor shall be entitled to draw on the security deposit in the event of any uncured default by the Company under the terms of the lease. The future minimum payments under the noncancelable operating lease at December 31, 2016, are as follows (in thousands): Year ending December 31, Amounts 2017 $ 1,460 2018 1,502 2019 1,686 2020 2,026 2021 1,439 Total $ 8,113 Rent expense under operating leases was $1.3 million, $0.9 million and $0.6 million for the years ended December 31, 2016, 2015 and 2014, respectively. Guarantees and Indemnifications The Company indemnifies each of its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at our request in such capacity, as permitted under Delaware law and in accordance with our certificate of incorporation and bylaws. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity. The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director and officer liability insurance. This insurance allows the transfer of risk associated with our exposure and may enable the Company to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations for any period presented.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	15. SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) Selected quarterly financial results from operations for the years ended December 31, 2016 and 2015 are as follows (in thousands, except per share amounts): 2016 Quarter End March 31, June 30 September 30 December 31 Total revenue $ — $ — $ — $ — Operating expenses 23,529 28,690 29,200 31,476 Net loss (23,467 ) (28,613 ) (29,031 ) (31,276 ) Net loss per share: Basic and Diluted (0.70 ) (0.83 ) (0.65 ) (0.66 ) 2015 Quarter End March 31, June 30 September 30 December 31 Total revenue $ 5,883 $ 18,143 $ — $ — Operating expenses 9,373 9,087 18,079 16,876 Net (loss) income (3,502 ) 9,007 (18,126 ) (17,000 ) Net (loss) income per share: Basic (0.19 ) 0.43 (0.70 ) (0.65 ) Diluted (0.19 ) 0.42 (0.70 ) (0.65 )

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	16. SUBSEQUENT EVENTS None.

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of Ardelyx and its wholly-owned subsidiary, Ardelyx Cayman Islands, and have been prepared in accordance with U.S. generally accepted accounting principles (“US GAAP”). Intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with US GAAP requires management to make estimates and judgments that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue, clinical trial accruals, contract manufacturing accruals, fair value of assets and liabilities, income taxes, and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Liquidity	Liquidity The Company has never been profitable on an annual basis and, as of December 31, 2016, the Company has an accumulated deficit of $213.9 million. The Company has incurred net losses of approximately $112.4 million, $29.6 million and $3.2 million in the years ended December 31, 2016, 2015 and 2014, respectively. The Company expects to continue to incur net operating losses for the foreseeable future, as the Company continues the development of, seeks regulatory approval for, and if approved, begins to commercialize, tenapanor and RDX7675. The Company will need additional funding to support its future operating activities and adequate funding may not be available to the Company on acceptable terms, or at all. The Company’s failure to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the business, results of operations, and financial condition. The Company will need to generate significant revenues to achieve profitability and may never do so.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original maturity date of 90 days or less on the date of purchase to be cash equivalents.
Short-Term Investments	Short-Term Investments Short-term investments consist of debt securities classified as available-for-sale available-for-sale available-for-sale
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and short-term investments. The Company is exposed to credit risks in the event of default by the issuers to the extent of the amount recorded in its Consolidated Balance Sheets. Cash, cash equivalents and short-term investments are invested through banks and other financial institutions in the United States.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized over the lesser of the estimated useful lives or the related remaining lease term.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The carrying value of long-lived assets, including property and equipment, are reviewed for impairment whenever events or changes in circumstances indicate that the asset may not be recoverable. An impairment loss is recognized when the total of estimated future undiscounted cash flows, expected to result from the use of the asset and its eventual disposition, are less than its carrying amount. Impairment, if any, would be assessed using discounted cash flows or other appropriate measures of fair value. Through December 31, 2016, there have been no such impairment losses.
Income Taxes	Income Taxes The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized.
Revenue Recognition	Revenue Recognition Revenue from research activities made under collaboration partnership agreements are recognized as the services are provided and when there is persuasive evidence that an arrangement exists, delivery has occurred, the price is fixed or determinable, and collectability is reasonably assured. Revenue generated from research and licensing agreements typically includes up-front For revenue agreements with multiple-element arrangements, such as license and development agreements, the Company allocates revenue to each unit of accounting based on the relative selling price of each unit. When applying the relative selling price method, the Company determines the selling price for each deliverable using vendor-specific objective evidence or third-party evidence. If neither exists, the Company uses its best estimate of selling price for that deliverable. Revenue allocated is then recognized when the four basic revenue recognition criteria are met for each deliverable. The Company recognizes revenue from upfront payments ratably over the term of its estimated period of performance under the agreement which is recorded as licensing revenue. Reimbursements for development costs incurred under the Company’s license agreement with AstraZeneca are classified as collaborative development revenue. The Company recognizes cost reimbursement revenue under collaboration partnership agreements as the related research and development costs for services are rendered. Deferred revenue represents the portion of research or license payments received which has not been earned. Revenues from milestones, if they are nonrefundable and deemed substantive, are recognized upon successful accomplishment of the milestones. To the extent that non-substantive non-substantive
Research and Development Costs	Research and Development Costs Research and development costs are charged to expense as incurred and consist of costs incurred to further the Company’s research and development activities including salaries and related employee benefits, costs associated with clinical trials, costs related to pre-commercialization
Accrued Research and Development Expenses	Accrued Research and Development Expenses As part of the process of preparing our financial statements, the Company is required to estimate its accrued expenses. This process involves reviewing open contracts and purchase orders, communicating with its personnel to identify services that have been performed on its behalf and estimating the level of service performed and the associated cost incurred for the service when the Company has not yet been invoiced or otherwise notified of the actual cost. The majority of the Company’s service providers invoice its monthly invoices in arrears for services performed or when contractual milestones are met. The Company makes estimates of its accrued expenses as of each balance sheet date in its financial statements based on facts and circumstances known to the Company at that time. The Company periodically confirms the accuracy of its estimates with the service providers and make adjustments if necessary. Examples of estimated accrued research and development expenses include fees paid to: • CROs in connection with clinical studies; • investigative sites in connection with clinical studies; • vendors related to product manufacturing, development and distribution of clinical supplies; • collaborator entities in connection with our collaboration agreements; and • vendors in connection with preclinical development activities. The Company records expenses related to clinical studies and manufacturing development activities based on its estimates of the services received and efforts expended pursuant to contracts with multiple CROs and manufacturing vendors that conduct and manage these activities on its behalf. The financial terms of these agreements are subject to negotiation, vary from contract to contract, and may result in uneven payment flows. There may be instances in which payments made to the Company’s vendors will exceed the level of services provided and result in a prepayment of the expense. Payments under some of these contracts depend on factors such as the successful enrollment of subjects and the completion of clinical trial milestones. In accruing service fees, the Company estimates the time period over which services will be performed, enrollment of subjects, number of sites activated and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the Company’s estimate, the Company will adjust the accrued or prepaid expense balance accordingly. To date, there have been no material differences from the Company’s estimates to the amounts actually incurred.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes compensation expense for all share-based payment awards made to employees and directors based on estimated fair values. For employee stock options, the Company determines the grant date fair value of the awards using the Black-Scholes option-pricing model and generally recognizes the fair value as stock-based compensation expense on a straight-line basis over the vesting period of the respective awards. Stock-based compensation expense is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company’s stock-based compensation is reduced for the estimated forfeitures at the date of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. For restricted stock, the compensation cost for these awards is based on the closing price of the Company’s common stock on the date of grant and recognized as compensation expense on a straight-line basis over the requisite service period. The Company accounts for equity instruments issued to nonemployees based on their fair values on the measurement dates using the Black-Scholes option-pricing model. The estimated fair values of the options granted to nonemployees are remeasured as they vest. As a result, the noncash charge to operations for nonemployee options with vesting conditions is affected each reporting period by changes in the fair value of the Company’s common stock.
Convertible Preferred Stock Warrant Liability	Convertible Preferred Stock Warrant Liability The Company accounted for freestanding warrants to purchase shares of convertible preferred stock that were contingently redeemable as liabilities in the balance sheets at their estimated fair value. Convertible preferred stock warrants were subject to remeasurement at each balance sheet date, and any change in fair value was recognized as a component of other expense, net in the statements of operations and comprehensive loss. The Company continued to adjust the carrying value of the warrants until the closing of its initial public offering (IPO), at which time the warrants were net exercised for shares of the Company’s common stock and the liability was reclassified to stockholders’ equity (deficit).
Comprehensive Loss	Comprehensive Loss Comprehensive loss is composed of two components: net loss and other comprehensive loss. Other comprehensive loss refers to gains and losses that under GAAP are recorded as an element of stockholders’ equity (deficit), but are excluded from net loss.
Net Loss per Share	Net Loss per Share Basic net loss per common share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. Diluted net loss per common share in the periods presented is the same as basic net loss per common share, since the effects of potentially dilutive securities are antidilutive.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May, 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers 2014-09”), 2014-09 2014-09, - Revenue from Contracts with Customers 2016-08 2016-10 2016-11 2014-09 2014-16 2016-12 In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements—Going Concern: Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern 2014-15”). 2014-15 2014-15 2014-15 In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) right-of-use 2016-02 2016-02 2016-02, In March 2016, the FASB issued Accounting Standards 2016-09, Improvements to Employee Share-Based Payment Accounting 2016-09 2016-09, In August 2016, the FASB issued Accounting Standards Update (ASU) 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments 2016-15 In November 2016, the FASB issued ASU 2016-18, Restricted Cash, 2016-08 2016-18 The Company has reviewed all other significant newly-issued accounting pronouncements and concluded that they either are not applicable to the Company’s operations or that no material effect is expected on its consolidated financial statements as a result of future adoption.
Fair Value Measurements	Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The three-level hierarchy for the inputs to valuation techniques is briefly summarized as follows: Level 1 – Valuations are based on quoted prices in active markets for identical assets or liabilities. Examples of assets and liabilities utilizing Level 1 inputs are certain money market funds, U.S. Treasuries and trading securities with quoted prices on active markets. Level 2 – Valuations based on inputs other than the quoted prices in active markets that are observable either directly or indirectly in active markets. Examples of assets and liabilities utilizing Level 2 inputs are U.S. government agency bonds, corporate bonds, commercial paper, certificates of deposit and over-the-counter Level 3 – Valuations based on unobservable inputs in which there is little or no market data, which require us to develop our own assumptions.

Cash, Cash Equivalents and In26

Cash, Cash Equivalents and Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Cash and Cash Equivalents [Abstract]
Schedule of Securities Classified as Cash and Cash Equivalents and Short-term Investments	Securities classified as cash and cash equivalents and short-term investments as of December 31, 2016 and December 31, 2015 are summarized below (in thousands). Estimated fair value is based on quoted market prices for these investments. December 31, 2016 Amortized Gross Unrealized Fair Value Gains Losses Cash and cash equivalents: Cash $ 3,638 $ — $ — $ 3,638 Money market funds 68,561 — — 68,561 Commercial paper 2,399 — — 2,399 Total cash and cash equivalents $ 74,598 $ — $ — $ 74,598 Short-term investments Corporate bonds 58,464 2 (56 ) $ 58,410 Commercial paper 62,946 5 (20 ) 62,931 Asset-backed securities 4,886 — (2 ) 4,884 Total short-term investments $ 126,296 $ 7 $ (78 ) $ 126,225 Total $ 200,894 $ 7 $ (78 ) $ 200,823 December 31, 2015 Amortized Gross Unrealized Fair Value Gains Losses Cash and cash equivalents: Cash $ 25,194 $ — $ — $ 25,194 Money market funds 81,810 — — 81,810 Total cash and cash equivalents $ 107,004 $ — $ — $ 107,004

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Summary of Fair Value Measurements of Company's Financial Assets	The following table sets forth the fair value of the Company’s financial assets measured on a recurring basis by level within the fair value hierarchy: December 31, 2016 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 68,561 $ 68,561 $ — $ — Corporate bonds 58,410 — 58,410 — Commercial paper 65,330 — 65,330 — Asset-backed securities 4,884 — 4,884 — Total $ 197,185 $ 68,561 $ 128,624 $ — December 31, 2015 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 81,810 $ 81,810 $ — $ — Certificates of deposit 100 — 100 — Total $ 81,910 $ 81,810 $ 100 $ —

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment consist of the following: December 31, 2016 2015 (in thousands) Laboratory equipment $ 5,487 $ 4,471 Office equipment and furniture 824 134 Leasehold improvements 7,783 3,914 Property and equipment, gross 14,094 8,519 Less: accumulated depreciation (5,103 ) (3,808 ) Total property and equipment, net $ 8,991 $ 4,711

Accrued and Other Liabilities (

Accrued and Other Liabilities (Tables)	12 Months Ended
	Dec. 31, 2016
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities and Other Liabilities	Accrued liabilities and other liabilities consist of the following (in thousands): December 31, 2016 2015 Accrued clinical trial expenses $ 6,694 $ 311 Accrued contract manufacturing 2,705 289 Accrued professional and consulting services 322 272 AstraZeneca clinical trial material accrual — 1,328 Other 684 380 $ 10,405 $ 2,580

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Summary of Activity Under 2008 Plan, 2014 Plan and Inducement Plan Including Grants to Nonemployees Issued	The following table summarizes activity under the 2008 Plan, the 2014 Plan, and the Inducement Plan, including grants to nonemployees issued: Options Issued and Outstanding Shares Available for Grant Number of Shares Weighted-Average Price per Share Aggregate Intrinsic Value (in thousands) Balance at December 31, 2013 3,914 1,162,829 $ 1.03 Options authorized 1,452,661 — — Options granted (188,888 ) 188,888 24.41 Options exercised — (336,398 ) 0.71 Options canceled 4,084 (4,084 ) 2.21 Options repurchased 3,511 (3,511 ) 0.55 Issuance of common stock for services (10,000 ) — — Balance at December 31, 2014 1,265,282 1,007,724 $ 5.51 Options authorized 743,569 — Options granted (379,709 ) 379,709 19.60 Options exercised — (77,784 ) 1.42 Options canceled 28,563 (28,563 ) 12.41 Issuance of common stock for services (13,285 ) — — Balance at December 31, 2015 1,644,420 1,281,086 $ 9.78 Options authorized 1,038,595 — Additional shares reserved under the Inducement Plan 1,000,000 — — Options granted (1,524,014 ) 1,524,014 11.42 Options exercised — (25,134 ) 2.19 Options canceled 67,743 (67,743 ) 16.67 Issuance of common stock for services (20,118 ) — — Balance at December 31, 2016 2,206,626 2,712,223 $ 10.60 $ 13,750 Vested and expected to vest at December 31, 2016 2,640,905 $ 10.54 $ 13,574 Vested at December 31, 2016 1,263,430 $ 7.58 $ 10,187
Summary of Non-vested RSU Activity	A summary of non-vested Number of Shares Weighted-Average Non-vested 9,425 $ 18.04 Granted 174,389 14.34 Vested (30,122 ) 16.35 Forfieted (5,000 ) 18.04 Non-vested 148,692 $ 14.17
Summary of Weighted Average Assumptions to Estimate Fair Value of Stock Option Awards and Employee Stock Purchase Plan	The estimated grant date fair value of employee stock options was calculated using the Black-Scholes option-pricing model, based on the following weighted assumptions: Year Ended December 31, 2016 2015 2014 Expected term ( years) 5.99 5.89 5.97 Volatility 77 % 75 % 94 % Risk-free interest rate 1.62 % 1.64 % 1.79 % Dividend yield — % — % — %
Summary of Stock-Based Compensation Recognized	Total stock-based compensation recognized was as follows (in thousands): Year Ended December 31, 2016 2015 2014 (in thousands) Research and development $ 2,786 $ 1,327 $ 1,376 General and administrative 2,531 1,307 316 Total stock-based compensation $ 5,317 $ 2,634 $ 1,692
2014 Employee Stock Purchase Plan [Member]
Summary of Weighted Average Assumptions to Estimate Fair Value of Stock Option Awards and Employee Stock Purchase Plan	The following table illustrates the weighted-average assumptions for the Black-Scholes option-pricing model used in determining the fair value of ESPP purchase rights granted to employees: Year Ended December 31, 2016 2016 2015 Expected term ( years) 0.5 0.5 Volatility 76 % 97 % Risk-free interest rate 0.48 % 0.16 % Dividend yield — % — %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Reconciliation of Statutory Federal Income Tax Rate to the Company's Effective Tax Rate	The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate: December 31, 2016 2015 2014 Expected income tax provision at the federal statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit 0.3 (3.8 ) 4.6 Change in valuation allowance (36.2 ) (30.7 ) (17.9 ) Nondeductible expenses — — (20.6 ) Tax credits 0.3 1.3 — Other 0.6 (1.7 ) (3.2 ) Income tax provision 0.0 % 0.1 % (2.1 %)
Significant Components of the Company's Deferred Tax Assets	Significant components of the Company’s deferred tax assets are as follows: December 31, 2016 2015 (in thousands) Deferred tax assets: Net operating loss carryforwards $ 68,639 $ 30,572 Research credits 2,643 1,919 Stock awards 2,583 1,011 Other 1,558 571 Gross deferred tax assets 75,423 34,073 Valuation allowance (74,520 ) (33,845 ) Total deferred tax assets 903 228 Deferred tax liabilities (903 ) (228 ) Net deferred tax assets $ — $ —
Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: December 31, 2016 2015 2014 (in thousands) Balance at beginning of year $ 3,298 $ 2,815 $ 1,411 Additions (subtractions) based on tax positions related to prior year 45 (58 ) 405 Additions based on tax positions related to current year 549 541 999 Balance at end of year $ 3,892 $ 3,298 $ 2,815

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Computation of Net Loss Per Common Share	The following table sets forth the computation of net loss per common share (in thousands, except share and per share amounts): December 31, 2016 2015 2014 Numerator: Net loss $ (112,387 ) $ (29,621 ) $ (3,214 ) Denominator: Weighted average number of shares outstanding—basic and diluted 40,118,522 22,892,640 10,248,337 Net loss per share-basic and diluted $ (2.80 ) $ (1.29 ) $ (0.31 )
Calculation of Anti-dilutive Potentially Dilutive Securities Not Included in Diluted Per Share	Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: December 31, 2016 2015 2014 Options to purchase common stock 2,557,314 1,244,442 1,007,724 Warrants to purchase common stock 2,172,899 300,302 — Total 4,730,213 1,544,744 1,007,724

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments Under the Noncancelable Operating Lease	The future minimum payments under the noncancelable operating lease at December 31, 2016, are as follows (in thousands): Year ending December 31, Amounts 2017 $ 1,460 2018 1,502 2019 1,686 2020 2,026 2021 1,439 Total $ 8,113

Selected Quarterly Financial 34

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Quarterly Financial Results from Operations	Selected quarterly financial results from operations for the years ended December 31, 2016 and 2015 are as follows (in thousands, except per share amounts): 2016 Quarter End March 31, June 30 September 30 December 31 Total revenue $ — $ — $ — $ — Operating expenses 23,529 28,690 29,200 31,476 Net loss (23,467 ) (28,613 ) (29,031 ) (31,276 ) Net loss per share: Basic and Diluted (0.70 ) (0.83 ) (0.65 ) (0.66 ) 2015 Quarter End March 31, June 30 September 30 December 31 Total revenue $ 5,883 $ 18,143 $ — $ — Operating expenses 9,373 9,087 18,079 16,876 Net (loss) income (3,502 ) 9,007 (18,126 ) (17,000 ) Net (loss) income per share: Basic (0.19 ) 0.43 (0.70 ) (0.65 ) Diluted (0.19 ) 0.42 (0.70 ) (0.65 )

Organization and Basis of Pre35

Organization and Basis of Presentation - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016Segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments	1

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 01, 2016	Dec. 31, 2013
Organization And Basis Of Presentation [Line Items]
Accumulated deficit	$ (213,875,000)				$ (101,488,000)				$ (213,875,000)	$ (101,488,000)
Net loss	(31,276,000)	$ (29,031,000)	$ (28,613,000)	$ (23,467,000)	(17,000,000)	$ (18,126,000)	$ 9,007,000	$ (3,502,000)	$ (112,387,000)	(29,621,000)	$ (3,214,000)
Cash and cash equivalents original maturity dates									90 days or less
Short-term investments maturity period description									Short-term investments consist of debt securities classified as available-for-sale and have maturities greater than 90 days, but less than 365 days from the date of acquisition.
Impairment loss of long lived assets									$ 0
Income tax benefit										(29,000)	67,000
Unrecognized excess tax benefit	$ 3,892,000				$ 3,298,000				3,892,000	$ 3,298,000	$ 2,815,000		$ 1,411,000
ASU 2016-09 [Member]
Organization And Basis Of Presentation [Line Items]
Income tax benefit									$ 800,000
Unrecognized excess tax benefit												$ 700,000
Minimum [Member]
Organization And Basis Of Presentation [Line Items]
Property and equipment, estimated useful lives									3 years
Maximum [Member]
Organization And Basis Of Presentation [Line Items]
Property and equipment, estimated useful lives									5 years

Cash, Cash Equivalents and In37

Cash, Cash Equivalents and Investments - Schedule of Securities Classified as Cash and Cash Equivalents and Short-term Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Cash Equivalents And Short Term Investments [Line Items]
Cash and cash equivalents, Amortized Cost	$ 74,598	$ 107,004	$ 107,286	$ 34,435
Cash and cash equivalents, Gross Unrealized Gains	0	0
Cash and cash equivalents, Gross Unrealized Losses	0	0
Cash and cash equivalents, Fair Value	74,598	107,004
Short-term investments, Amortized Cost	126,296
Short-term investments, Gross Unrealized Gains	7
Short-term investments, Gross Unrealized Losses	(78)
Short-term investments, Fair Value	126,225
Cash equivalents and short-term investments, Amortized Cost	200,894
Cash equivalents and short-term investments, Gross Unrealized Gains	7
Cash equivalents and short-term investments, Gross Unrealized Losses	(78)
Cash equivalents and short-term investments, Fair Value	200,823
Cash [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Cash and cash equivalents, Amortized Cost	3,638	25,194
Cash and cash equivalents, Gross Unrealized Gains	0	0
Cash and cash equivalents, Gross Unrealized Losses	0	0
Cash and cash equivalents, Fair Value	3,638	25,194
Money Market Funds [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Cash and cash equivalents, Amortized Cost	68,561	81,810
Cash and cash equivalents, Gross Unrealized Gains	0	0
Cash and cash equivalents, Gross Unrealized Losses	0	0
Cash and cash equivalents, Fair Value	68,561	$ 81,810
Commercial Paper (Cash Equivalents) [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Cash and cash equivalents, Amortized Cost	2,399
Cash and cash equivalents, Gross Unrealized Gains	0
Cash and cash equivalents, Gross Unrealized Losses	0
Cash and cash equivalents, Fair Value	2,399
Corporate Bonds (Investments) [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Short-term investments, Amortized Cost	58,464
Short-term investments, Gross Unrealized Gains	2
Short-term investments, Gross Unrealized Losses	(56)
Short-term investments, Fair Value	58,410
Commercial Paper (Investments) [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Short-term investments, Amortized Cost	62,946
Short-term investments, Gross Unrealized Gains	5
Short-term investments, Gross Unrealized Losses	(20)
Short-term investments, Fair Value	62,931
Asset-Backed Securities [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Short-term investments, Amortized Cost	4,886
Short-term investments, Gross Unrealized Losses	(2)
Short-term investments, Fair Value	$ 4,884

Cash, Cash Equivalents and In38

Cash, Cash Equivalents and Investments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)
Cash Cash Equivalents And Short Term Investments [Line Items]
Bank accounts	$ 24,000,000
Available-for-sale securities, realized gains or losses	0
Investment in continuous unrealized loss position for more than one year	$ 0
Maximum [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Available for sale securities contractual maturity period	1 year

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value Measurements of Company's Financial Assets (Detail) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets:
Assets at fair value	$ 197,185	$ 81,910
Level 1 [Member]
Assets:
Assets at fair value	68,561	81,810
Level 2 [Member]
Assets:
Assets at fair value	128,624	100
Money Market Funds [Member]
Assets:
Assets at fair value	68,561	81,810
Money Market Funds [Member] | Level 1 [Member]
Assets:
Assets at fair value	68,561	81,810
Certificates of Deposit [Member]
Assets:
Assets at fair value		100
Certificates of Deposit [Member] | Level 2 [Member]
Assets:
Assets at fair value		$ 100
Corporate Bonds [Member]
Assets:
Assets at fair value	58,410
Corporate Bonds [Member] | Level 2 [Member]
Assets:
Assets at fair value	58,410
Commercial Paper [Member]
Assets:
Assets at fair value	65,330
Commercial Paper [Member] | Level 2 [Member]
Assets:
Assets at fair value	65,330
Asset-Backed Securities [Member]
Assets:
Assets at fair value	4,884
Asset-Backed Securities [Member] | Level 2 [Member]
Assets:
Assets at fair value	$ 4,884

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	Dec. 31, 2016USD ($)
Fair Value Disclosures [Abstract]
Transfer of assets from Level 1 to Level 2	$ 0
Transfer of assets from Level 2 to Level 1	$ 0

Property and Equipment - Summar

Property and Equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 14,094	$ 8,519
Less: accumulated depreciation	(5,103)	(3,808)
Total property and equipment, net	8,991	4,711
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	5,487	4,471
Office Equipment And Furniture [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	824	134
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 7,783	$ 3,914

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 1.3	$ 0.8	$ 0.3

Accrued and Other Liabilities -

Accrued and Other Liabilities - Schedule of Accrued Liabilities and Other Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Accrued clinical trial expenses	$ 6,694	$ 311
Accrued contract manufacturing	2,705	289
Accrued professional and consulting services	322	272
AstraZeneca clinical trial material accrual		1,328
Other	684	380
Accrued liabilities and other liabilities	$ 10,405	$ 2,580

Collaboration and Licensing A44

Collaboration and Licensing Agreements - Additional Information (Detail) - USD ($)	1 Months Ended			3 Months Ended	6 Months Ended
	Sep. 30, 2015	May 31, 2014	Oct. 31, 2012	Jun. 30, 2015	Jun. 30, 2016
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Payment received on termination and return of rights	$ 0
AstraZeneca [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Upfront payment received			$ 75,000,000
Amount of upfront payment for return of licenses				$ 15,000,000
Amount of reimbursement paid for certain research and development expenses in consideration of acceleration of transfer of information and materials				10,000,000
Recognized deferred revenue				$ 43,100,000
Recognition of licensing and collaborative development revenue					$ 0
Sanofi [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenue recognized		$ 1,250,000

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 24, 2014	Dec. 31, 2014
Class of Stock [Line Items]
Convertible preferred stock converted to common stock, value		$ 56,155
Common Stock [Member]
Class of Stock [Line Items]
Convertible preferred stock converted to common stock, shares	11,517,222
Convertible preferred stock converted to common stock, value	$ 56,200

Preferred Stock Warrants - Addi

Preferred Stock Warrants - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2013	Aug. 31, 2011
Class of Stock Disclosures [Abstract]
Convertible preferred stock warrant liability	$ 6.5
Company issued warrants		574,953

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Detail) - USD ($)	Jan. 01, 2017	Jan. 01, 2015	Jun. 18, 2014	Jun. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 30, 2016	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					4 years
Common stock reserved					1,454,549
Increase in shares reserved for issuance, maximum shares to be issued up on exercise of stock options			1,153,279
Number of shares granted during the period					1,524,014	379,709	188,888
Weighted-average grant-date estimated fair value of options granted					$ 7.69	$ 12.91	$ 18.53
Estimated fair value of common stock					$ 14.20
Estimated fair value of options vested during period					$ 6,400,000	$ 2,400,000	$ 500,000
Estimated fair value of restricted stock vested during period					$ 500,000
Shares available for future grant					2,206,626	1,644,420	1,265,282		3,914
Stock-based compensation charge							$ 800,000
Gross proceeds from issuance of common stock				$ 77,800,000
Proceeds from issuance of common stock, net of issuance costs				$ 74,300,000	$ 190,573,000	$ 74,323,000	$ 61,241,000
Common stock sold and issued				7,242,992
Purchase price of common shares				$ 10.70
Warrants issued to purchase common stock				2,172,899
Purchase price for warrants				$ 0.125
Warrants exercise price per share				$ 13.91
Warrants expiration term				5 years
Warrants description					The warrants are exercisable for an exercise price of $13.91 per share at any time prior to the earlier of (i) 5 years from the date of issuance or (ii) certain changes in control of the Company.
Maximum warrants ownership percentage by each holder of warrants				9.99%
Number of warrants exercised					0	0
Expected dividend yield					$ 0
Issuance of common stock for services (Shares)					20,118	13,285	10,000
Issuance of common stock for services, amount					$ 187,000	$ 194,000	$ 208,000
Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares reserved for issuance, maximum shares to be issued up on exercise of stock options	1,892,376
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock based compensation expense					$ 100,000
Unrecognized stock based compensation expense, weighted-average remaining recognition period					2 months 12 days
2014 Equity Incentive Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved					1,419,328
Increase in shares reserved for issuance, maximum shares to be issued up on exercise of stock options					10,683,053
Possible increase in shares reserved for issuance as percentage of outstanding stock					4.00%
2008 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved					35,221
2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved					202,762
Increase in shares reserved for issuance, maximum shares to be issued up on exercise of stock options		185,892			2,230,374
Possible increase in shares reserved for issuance as percentage of outstanding stock					1.00%
Employee stock purchase plan initial offering commenced period					Sep. 1, 2014
Employee stock purchase plan initial offering ending period					Feb. 27, 2015
Shares available for future grant					278,020
Number of shares sold under the plan					69,054	41,580	0
Weighted-average purchase price					$ 8.34	$ 13.25
Proceeds from issuance of shares					$ 600,000	$ 600,000
2016 Employment Commencement Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted during the period					0
2016 Employment Commencement Incentive Plan [Member] | Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved								1,000,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based award accelerated vesting number of shares							58,969
Options to Purchase Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock based compensation expense					$ 11,500,000
Unrecognized stock based compensation expense, weighted-average remaining recognition period					2 years 10 months 24 days
Non Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted during the period					12,500	5,000	10,000
Weighted-average grant-date estimated fair value of options granted					$ 13.71	$ 18.58	$ 20.77
Stock-based compensation charge					$ 100,000	$ 200,000	$ 100,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock based compensation expense					$ 2,100,000
Unrecognized stock based compensation expense, weighted-average remaining recognition period					3 years 6 months

Equity Incentive Plans - Summar

Equity Incentive Plans - Summary of Activity Under 2008 Plan, 2014 Plan and Inducement Plan Including Grants to Nonemployees Issued (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Shares Available for Grant, Beginning balance	1,644,420	1,265,282	3,914
Options Issued and Outstanding Average Exercise Price per Share, Additional shares reserved under the Inducement Plan	$ 0
Shares Available for Grant, Options authorized	1,038,595	743,569	1,452,661
Shares Available for Grant, Additional shares reserved under the Inducement Plan	1,000,000
Shares Available for Grant, Options granted	(1,524,014)	(379,709)	(188,888)
Shares Available for Grant, Options exercised	0	0	0
Shares Available for Grant, Options canceled	67,743	28,563	4,084
Shares Available for Grant, Options repurchased			3,511
Shares Available for Grant, Issuance of common stock for services	(20,118)	(13,285)	(10,000)
Shares Available for Grant, Ending balance	2,206,626	1,644,420	1,265,282
Options Issued and Outstanding Number of Shares, Beginning balance	1,281,086	1,007,724	1,162,829
Options Issued and Outstanding Number of Shares, Options authorized	0	0	0
Options Issued and Outstanding Number of Shares, Additional shares reserved under the Inducement Plan	0
Options Issued and Outstanding Number of Shares, Options granted	1,524,014	379,709	188,888
Options Issued and Outstanding Number of Shares, Options exercised	(25,134)	(77,784)	(336,398)
Options Issued and Outstanding Number, Options cancelled	(67,743)	(28,563)	(4,084)
Options Issued and Outstanding Number of Shares, Options repurchased			(3,511)
Options Issued and Outstanding Number of Shares, Issuance of common stock for services	0	0	0
Options Issued and Outstanding Number of Shares, Ending balance	2,712,223	1,281,086	1,007,724
Options Issued and Outstanding Average Exercise Price per Share, Beginning balance	$ 9.78	$ 5.51	$ 1.03
Options Issued and Outstanding Number of Shares, Expected to vest	2,640,905
Options Issued and Outstanding Number of Shares, Vested	1,263,430
Options Issued and Outstanding Average Exercise Price per Share, Options granted	$ 11.42	19.60	24.41
Options Issued and Outstanding Average Exercise Price per Share, Options exercised	2.19	1.42	0.71
Options Issued and Outstanding Average Exercise Price per Share, Options canceled	16.67	12.41	2.21
Options Issued and Outstanding Average Exercise Price per Share, Options repurchased			0.55
Options Issued and Outstanding Average Exercise Price per Share, Issuance of common stock for services	0	0	0
Options Issued and Outstanding Average Exercise Price per Share, Ending balance	10.60	$ 9.78	$ 5.51
Options Issued and Outstanding Average Exercise Price per Share, Expected to vest	10.54
Options Issued and Outstanding Average Exercise Price per Share, Vested	$ 7.58
Aggregate Intrinsic Value, Ending balance	$ 13,750
Aggregate Intrinsic Value, Expected to Vest	13,574
Aggregate Intrinsic Value, Vested	$ 10,187

Equity Incentive Plans - Summ49

Equity Incentive Plans - Summary of Non-vested RSU Activity (Detail) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Beginning balance | shares	9,425
Number of Shares, Granted | shares	174,389
Number of Shares, Vested | shares	(30,122)
Number of Shares, Forfieted | shares	(5,000)
Number of Shares, Ending balance | shares	148,692
Weighted-Average Grant Date Fair Value Per Share, Beginning balance | $ / shares	$ 18.04
Weighted-Average Grant Date Fair Value Per Share, Granted | $ / shares	14.34
Weighted-Average Grant Date Fair Value Per Share, Vested | $ / shares	16.35
Weighted-Average Grant Date Fair Value Per Share, Forfieted | $ / shares	18.04
Weighted-Average Grant Date Fair Value Per Share, Ending balance | $ / shares	$ 14.17

Equity Incentive Plans - Summ50

Equity Incentive Plans - Summary of Weighted Average Assumptions to Estimate Fair value of Stock Option Awards and Employee Stock Purchase Plan (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term ( years)	5 years 11 months 27 days	5 years 10 months 21 days	5 years 11 months 19 days
Volatility	77.00%	75.00%	94.00%
Risk-free interest rate	1.62%	1.64%	1.79%
Dividend yield	0.00%	0.00%	0.00%
2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term ( years)	6 months	6 months
Volatility	76.00%	97.00%
Risk-free interest rate	0.48%	0.16%
Dividend yield	0.00%	0.00%

Equity Incentive Plans - Summ51

Equity Incentive Plans - Summary of Stock-Based Compensation Expense Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	$ 5,317	$ 2,634	$ 1,692
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	2,786	1,327	1,376
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	$ 2,531	$ 1,307	$ 316

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Statutory Federal Income Tax Rate to the Company's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Expected income tax provision at the federal statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	0.30%	(3.80%)	4.60%
Change in valuation allowance	(36.20%)	(30.70%)	(17.90%)
Nondeductible expenses			(20.60%)
Tax credits	0.30%	1.30%
Other	0.60%	(1.70%)	(3.20%)
Income tax provision	0.00%	0.10%	(2.10%)

Income Taxes - Significant Comp

Income Taxes - Significant Components of the Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Assets, Net [Abstract]
Net operating loss carryforwards	$ 68,639	$ 30,572
Research credits	2,643	1,919
Stock awards	2,583	1,011
Other	1,558	571
Gross deferred tax assets	75,423	34,073
Valuation allowance	(74,520)	(33,845)
Total deferred tax assets	903	228
Deferred tax liabilities	(903)	(228)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Line Items]
Increase (decrease) in deferred tax valuation allowance	$ 40,700,000	$ 9,100,000
Unrecognized tax benefits that would affect the effective tax rate if recognized	3,900,000	3,300,000	$ 2,800,000
Accrued interest and penalties related to unrecognized tax benefits	0	$ 0	$ 0
Federal Tax Authority [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 192,000,000
Operating loss carryforward expiration year	2,030
Federal Tax Authority [Member] | Research and Development Tax Credit [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 3,400,000
Tax credit carryforward expiration year	2,027
State Tax Authority [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforward expiration year	2,025
Other net operating losses	$ 1,100,000
State Tax Authority [Member] | California
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 31,100,000
Operating loss carryforward expiration year	2,030
State Tax Authority [Member] | Research and Development Tax Credit [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 3,800,000
State Tax Authority [Member] | Minimum Tax Credit Carryforward [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforwards	$ 200,000

Income Taxes - Reconciliation55

Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 3,298	$ 2,815	$ 1,411
Additions (subtractions) based on tax positions related to prior year	45	(58)	405
Additions based on tax positions related to current year	549	541	999
Balance at end of year	$ 3,892	$ 3,298	$ 2,815

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Net Loss Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator:
Net loss	$ (31,276)	$ (29,031)	$ (28,613)	$ (23,467)	$ (17,000)	$ (18,126)	$ 9,007	$ (3,502)	$ (112,387)	$ (29,621)	$ (3,214)
Denominator:
Weighted average number of shares outstanding-basic and diluted									40,118,522	22,892,640	10,248,337
Net loss per share-basic and diluted	$ (0.66)	$ (0.65)	$ (0.83)	$ (0.70)					$ (2.80)	$ (1.29)	$ (0.31)

Net Loss per Share - Calculatio

Net Loss per Share - Calculation of Anti-dilutive Potentially Dilutive Securities Not Included in Diluted Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, shares	4,730,213	1,544,744	1,007,724
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, shares	2,557,314	1,244,442	1,007,724
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, shares	2,172,899	300,302

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Related party transactions	$ 0	$ 0
Clinical Operations Consulting Arrangement [Member] | Spouse of Executive Officer [Member]
Related Party Transaction [Line Items]
Research and development service expenses			$ 200,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	1 Months Ended			12 Months Ended
	May 31, 2016	Sep. 30, 2014	Dec. 31, 2012	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loss Contingencies [Line Items]
Amount provided lessor with irrevocable letter of credit				$ 100,000
Rent expense under operating leases				$ 1,300,000	$ 900,000	$ 600,000
December 2012, Amended Facility Lease Agreement [Member]
Loss Contingencies [Line Items]
Lease expiration date			Sep. 30, 2016
September 2014, Amended Facility Lease Agreement [Member]
Loss Contingencies [Line Items]
Lease expiration date		Sep. 30, 2019
Lease improvement allowance maximum amount		$ 600,000
May 2016, Amended Facility Lease Agreement [Member]
Loss Contingencies [Line Items]
Lease expiration date	Sep. 30, 2021
Lease improvement allowance maximum amount	$ 400,000

Commitments and Contingencies60

Commitments and Contingencies - Schedule of Future Minimum Payments Under the Noncancelable Operating Lease (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,017	$ 1,460
2,018	1,502
2,019	1,686
2,020	2,026
2,021	1,439
Total	$ 8,113

Selected Quarterly Financial 61

Selected Quarterly Financial Data (Unaudited) - Schedule of Selected Quarterly Financial Results from Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Total revenue							$ 18,143	$ 5,883		$ 24,026	$ 31,623
Operating expenses	$ 31,476	$ 29,200	$ 28,690	$ 23,529	$ 16,876	$ 18,079	9,087	9,373	$ 112,895	53,415	33,187
Net (loss) income	$ (31,276)	$ (29,031)	$ (28,613)	$ (23,467)	$ (17,000)	$ (18,126)	$ 9,007	$ (3,502)	$ (112,387)	$ (29,621)	$ (3,214)
Net (loss) income per share:
Basic and Diluted	$ (0.66)	$ (0.65)	$ (0.83)	$ (0.70)					$ (2.80)	$ (1.29)	$ (0.31)
Basic					$ (0.65)	$ (0.70)	$ 0.43	$ (0.19)
Diluted					$ (0.65)	$ (0.70)	$ 0.42	$ (0.19)