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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2017	Nov. 01, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Trading Symbol	ARDX
Entity Registrant Name	Ardelyx, Inc.
Entity Central Index Key	0001437402
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		47,534,979

Condensed Consolidated Balance Sheets - USD ($)
$ in Thousands

Sep. 30, 2017

Dec. 31, 2016

^[1]

Current assets:

Cash and cash equivalents

$ 59,454

$ 74,598

Short-term investments

69,834

126,225

Prepaid expenses and other current assets

4,342

3,169

Total current assets

133,630

203,992

Property and equipment, net

8,622

8,991

Other assets

853

148

Total assets

143,105

213,131

Current liabilities:

Accounts payable

1,723

5,635

Accrued compensation and benefits

2,722

3,161

Accrued and other liabilities

11,282

10,405

Total current liabilities

15,727

19,201

Other long-term liabilities

741

779

Total liabilities

16,468

19,980

Commitments and contingencies (Note 9)

Stockholders' equity:

Preferred stock, $0.0001 par value; 5,000,000 shares authorized; no shares issued and outstanding as of September 30, 2017 and December 31, 2016.

Common stock, $0.0001 par value; 300,000,000 shares authorized; 47,503,970 and 47,309,422 shares issued and outstanding as of September 30, 2017 and December 31, 2016, respectively.

Additional paid-in capital

414,970

407,092

Accumulated deficit

(288,328)

(213,875)

Accumulated other comprehensive loss

(10)

(71)

Total stockholders' equity

126,637

193,151

Total liabilities and stockholders' equity

$ 143,105

$ 213,131

[1]	Derived from the audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2016.

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares

Sep. 30, 2017

Dec. 31, 2016

^[1]

Statement of Financial Position [Abstract]

Preferred stock, par value

$ 0.0001

Preferred stock, shares authorized

5,000,000

Preferred stock, shares issued

Preferred stock, shares outstanding

Common stock, par value

$ 0.0001

Common stock, shares authorized

300,000,000

Common stock, shares issued

47,503,970

47,309,422

Common stock, shares outstanding

47,503,970

47,309,422

[1]	Derived from the audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2016.

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating expenses:
Research and development	$ 15,365	$ 24,863	$ 58,325	$ 67,951
General and administrative	5,860	4,337	17,752	13,469
Total operating expenses	21,225	29,200	76,077	81,420
Loss from operations	(21,225)	(29,200)	(76,077)	(81,420)
Other income, net	501	169	1,624	307
Loss before provision for income taxes	(20,724)	(29,031)	(74,453)	(81,113)
Provision for income taxes	0	0	0	0
Net loss	$ (20,724)	$ (29,031)	$ (74,453)	$ (81,113)
Net loss per common share - basic and diluted	$ (0.44)	$ (0.65)	$ (1.57)	$ (2.15)
Shares used in computing net loss per share - basic and diluted	47,464,310	44,935,126	47,404,039	37,706,045
Comprehensive Loss:
Net loss	$ (20,724)	$ (29,031)	$ (74,453)	$ (81,113)
Unrealized gain (loss) on available-for-sale securities, net of tax	30	(25)	61	(25)
Comprehensive loss	$ (20,694)	$ (29,056)	$ (74,392)	$ (81,138)

Condensed Consolidated Statements of Cash Flows - USD ($)
$ in Thousands

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Operating activities

Net loss

$ (74,453)

$ (81,113)

Adjustments to reconcile net loss to net cash used in operating activities:

Depreciation expense

1,965

904

Amortization of deferred financing costs

360

289

Amortization of deferred compensation for services

142

148

Amortization of premium on investment securities

(11)

Stock-based compensation

7,001

3,767

Issuance of common stock for services

202

187

Changes in operating assets and liabilities:

Prepaid expenses and other assets

(2,380)

719

Accounts payable

(3,182)

2,678

Accrued compensation and benefits

(439)

(139)

Accrued and other liabilities

839

6,785

Net cash used in operating activities

(69,888)

(65,786)

Investing activities

Proceeds from maturities of investments

109,923

Sales and redemptions of investments

16,857

Purchases of investments

(70,384)

(69,740)

Purchases of property and equipment

(2,327)

(2,108)

Net cash provided by (used in) investing activities

54,069

(71,848)

Financing activities

Proceeds from issuance of common stock, net of issuance costs

190,574

Proceeds from issuance of common stock under stock plans

675

416

Net cash provided by financing activities

675

190,990

Net (decrease) increase in cash and cash equivalents

(15,144)

53,356

Cash and cash equivalents at beginning of period

74,598

^[1]

107,004

Cash and cash equivalents at end of period

$ 59,454

$ 160,360

[1]	Derived from the audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2016.

Organization and Basis of Presentation	9 Months Ended
Organization and Basis of Presentation	Sep. 30, 2017
Accounting Policies [Abstract]
Organization and Basis of Presentation	NOTE 1. ORGANIZATION AND BASIS OF PRESENTATION Ardelyx, Inc., or “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 deliver 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 a research and development-focused company to an integrated biotechnology company, by establishing regional and global partnerships to leverage its own commercial capabilities and experience to help build its cardiorenal and GI portfolios. The Company operates in only one business segment, which is the development of biopharmaceutical products. *Basis of Presentation* These unaudited condensed consolidated financial statements and the related footnote information of the Company have been prepared pursuant to the requirements of the Securities and Exchange Commission, or the SEC, for interim reporting. As permitted under those rules and regulations, certain footnotes or other financial information that are normally required by U.S. generally accepted accounting principles, or U.S. GAAP, have been condensed or omitted pursuant to such rules and regulations. In the opinion of the Company’s management, the accompanying interim unaudited condensed consolidated financial statements include all adjustments (consisting only of normal recurring adjustments) necessary for a fair presentation of the information for the periods presented. The results for the three and nine months ended September 30, 2017, are not necessarily indicative of results to be expected for the entire year ending December 31, 2017, or future operating periods. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2016, included in the Company’s Annual Report on Form 10-K filed with the SEC (the “2016 Form 10-K”). The balance sheet at December 31, 2016, has been derived from the audited consolidated financial statements at that date, as filed with the 2016 Form 10-K. The accompanying condensed consolidated financial statements include the accounts of Ardelyx, Inc. and its wholly-owned subsidiary, Ardelyx Cayman Islands, and have been prepared in accordance with U.S. GAAP. Intercompany transactions and balances have been eliminated in consolidation.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Although management believes these estimates are based upon reasonable assumptions within the bounds of its knowledge of the Company’s business and operations, actual results could differ materially from those estimates.

Accrued Research and Development Expenses

As part of the process of preparing its 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 submit 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 makes adjustments if necessary. Examples of estimated accrued research and development expenses include fees paid to:

•

contract research organizations (“CROs”) in connection with clinical studies;

•

investigative sites in connection with clinical studies;

•

vendors related to product manufacturing, development and distribution of clinical supplies; 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.

Reclassification

Approximately $0.2 million in the nine months ended September 30, 2016, which was previously recorded within “Proceeds from issuance of common stock under stock plans” in Financing activities in the Statement of Cash Flows, has been reclassified as a non-cash item “Issuance of common stock for services” within Operating activities.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014-09 will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. In July 2015, the FASB voted to approve a deferral of the effective date of this ASU by one year, and to permit entities to adopt up to one year earlier if they choose. Therefore, the new standard will become effective for the Company on January 1, 2018, with early application permitted for periods beginning on or after January 1, 2017. The standard permits the use of two transition methods on adoption, either retrospectively to each prior period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective method). Since the issuance of ASU 2014-09, the FASB has issued several amendments which clarify certain points in the new Topic 606 - Revenue from Contracts with Customers, including ASU 2016-08 (“Principal versus Agent Considerations—Reporting Revenue Gross versus Net”), ASU 2016-10 (“Identifying Performance Obligations and Licensing”), ASU 2016-11 (“Rescission of SEC Guidance Because of Accounting Standards Updates 2014-09 and 2014-16 Pursuant to Staff Announcements at the March 3, 2016 EITF Meeting”) and ASU 2016-12 (“Narrow-Scope Improvements and Practical Expedients”). The Company plans to adopt all these standards using the modified retrospective method on January 1, 2018, and will modify its accounting policies to reflect the requirements of these standards. The Company did not recognize revenue for the nine months ended September 30, 2017 or 2016, therefore the planned adoption of these standards will not affect the Company’s condensed consolidated financial statements for these periods, or for future periods until the Company reports revenues.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which replaces most current lease guidance when it becomes effective. This standard update intends to increase the transparency and improve comparability by requiring entities to recognize assets and liabilities on the balance sheet for all leases, with certain exceptions. The new standard states that a lessee will recognize a lease liability for the obligation to make lease payments and a right-of-use asset for the right to use the underlying asset for the lease term. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the consolidated statements of operations. The new guidance will be effective for the Company starting in the first quarter of fiscal 2019. Early adoption is permitted. The Company is currently evaluating the timing of adoption and the effect that the new guidance will have on its consolidated financial statements and related disclosures.

In October 2016, the FASB issued ASU No. 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory (ASU 2016-16). This update is to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. ASU 2016-16 amends the guidance to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. Consequently, the amendments in this update eliminate the exception for an intra-entity transfer of an asset other than inventory. The amendments in this update do not include new disclosure requirements; however, existing disclosure requirements might be applicable when accounting for the current and deferred income taxes for an intra-entity transfer of an asset other than inventory. ASU 2016-16 is effective for our interim and annual reporting periods during the year ending December 31, 2018, and all annual and interim reporting periods thereafter. Early adoption is permitted. The adoption of ASU 2016-16 is not expected to have a material effect on the Company’s condensed consolidated financial statements.

In May 2017, FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718)- Scope of Modification Accounting (ASU 2017-09). The amendments included in this update provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. The amendments in this update will be applied prospectively to an award modified on or after the adoption date. The amendments in ASU 2017-09 are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. The adoption of this standard is not expected to have a material impact on the Company’s condensed consolidated financial statements.

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 no material effect is expected on its condensed consolidated financial statements as a result of future adoption.

Cash, Cash Equivalents and Investments

9 Months Ended

Sep. 30, 2017

Cash and Cash Equivalents [Abstract]

Cash, Cash Equivalents and Investments

NOTE 3. CASH, CASH EQUIVALENTS AND INVESTMENTS

Securities classified as cash, cash equivalents and short-term investments as of September 30, 2017 and December 31, 2016, are summarized below (in thousands). Estimated fair value is based on quoted market prices for these investments.


	September 30, 2017
	Amortized Cost		Gross Unrealized					Fair Value
	Amortized Cost		Gains		Losses			Fair Value
Cash and cash equivalents:
Cash	$	7,254	$	—	$	—		$	7,254
Money market funds		44,155		—		—			44,155
U.S. treasury securities		1,799		—		—			1,799
U.S. government-sponsored agency bonds		1,800		—		—			1,800
Corporate bonds		2,246		—		—			2,246
Commercial paper		2,200		—		—			2,200

Total cash and cash equivalents		59,454		—		—			59,454

Short-term investments
U.S. treasury securities		2,988		—		—			2,988
Corporate bonds		38,247		1		(9	)		38,239
Commercial paper		21,382		1		(3	)		21,380
Asset-backed securities		7,227		1		(1	)		7,227

Total short-term investments		69,844		3		(13	)		69,834

Total cash equivalents and investments	$	129,298	$	3	$	(13	)	$	129,288


	December 31, 2016
	Amortized Cost		Gross Unrealized					Fair Value
	Amortized Cost		Gains		Losses			Fair Value
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 cash equivalents and investments	$	200,894	$	7	$	(78	)	$	200,823

Cash equivalents consist of money market funds and other 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 gain (loss)” within stockholders’ equity on the Company’s condensed consolidated balance sheets. The Company uses the specific identification method to determine the amount of realized gains or losses on sales of marketable securities. Realized gains or losses have been insignificant and are included in “other income, net” in the consolidated condensed statement of operations.

All available-for-sale securities held as of September 30, 2017, had contractual maturities of less than one year. The Company’s available-for-sale securities are subject to a periodic impairment review. The Company considers a debt security to be impaired when its fair value is less than its carrying cost, in which case the Company would further review the investment to determine whether it is other-than-temporarily impaired. When the Company evaluates an investment for other-than-temporary impairment, the Company reviews factors such as the length of time and extent to which fair value has been below cost basis, the financial condition of the issuer and any changes thereto, intent to sell, and whether it is more likely than not the Company will be required to sell the investment before the recovery of it cost basis. If an investment is other-than-temporarily impaired, the Company writes it down through the statement of operations to its fair value and establishes that value as a new cost basis for the investment. The Company did not identify any of its available-for-sale securities as other-than-temporarily impaired in any of the periods presented. As of September 30, 2017, no investment was in a continuous unrealized loss position for more than one year, the unrealized losses were not due to a change in credit risk, and the Company believes that is more likely than not the investments will be held until maturity or a forecasted recovery of fair value.

Fair Value Measurements

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

NOTE 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 and readily accessible by the Company at the reporting date. 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 Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Examples of assets and liabilities utilizing Level 2 inputs are corporate bonds, commercial paper, certificates of deposit and over-the-counter derivatives.

Level 3	–	Valuations based on unobservable inputs in which there is little or no market data, which require the Company to develop its 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 (in thousands):


	September 30, 2017
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	44,155	$	44,155	$	—	$	—
U.S. treasury securities		4,787		4,787		—		—
U.S. government-sponsored agency bonds		1,800		1,800		—		—
Corporate bonds		40,485		—		40,485		—
Commercial paper		23,580		—		23,580		—
Asset-backed securities		7,227		—		7,227		—

Total	$	122,034	$	50,742	$	71,292	$	—


	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	$	—

Where quoted prices are available in an active market, securities are classified as Level 1. The Company classifies money market funds, U.S. treasury securities and U.S. government-sponsored agency bonds 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 corporate bonds, commercial paper and asset-backed securities 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, short-term investments, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values at September 30, 2017 and December 31, 2016, due to their short-term nature.

- Definition

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

+ References + Details

Stock-Based Compensation

9 Months Ended

Sep. 30, 2017

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

Stock-Based Compensation

NOTE 5. STOCK-BASED COMPENSATION

The following table presents stock-based compensation expense recognized for stock options, restricted stock units, or RSUs, performance-based restricted stock units, or PRSUs, and the Company’s employee stock purchase program, or ESPP, in the Company’s statements of operations (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Research and development	$	916	$	685	$	3,361	$	1,992
General and administrative		1,186		606		3,640		1,775

Total	$	2,102	$	1,291	$	7,001	$	3,767

In January 2017, the Company granted PRSU awards to certain employees which vest upon the achievement of certain performance conditions, subject to the employees’ continued service relationship with the Company. None vested during the three and nine months ended September 30, 2017. However, the related compensation cost is recognized as an expense over the estimated vesting period when achievement of the milestone is considered probable. The expense recognized for these awards is based on the grant date fair value of the Company’s common stock multiplied by the number of units granted. The Company recognized $0.1 million and $0.7 million of related expense during the three and nine months ended September 30, 2017, respectively.

At September 30, 2017, the Company had $15.5 million, $2.8 million, $1.1 million and $0.1 million of total unrecognized compensation expense, net of estimated forfeitures, related to stock option grants, RSU grants, PRSUs and ESPP, respectively, that will be recognized over an average vesting period of 2.6 years, 1.9 years, 1.1 years and 0.4 years, respectively.

Net Loss Per Share

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Net Loss Per Share

NOTE 6. NET LOSS PER SHARE

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per common share is computed giving effect to all potential dilutive common shares, comprising common stock issuable upon exercise of stock options and warrants, and unvested restricted common stock and restricted stock units. The Company uses the treasury-stock method to compute diluted earnings per share with respect to its stock options and warrants. For purposes of this calculation, options and warrants to purchase common stock are considered to be potential common shares and are only included in the calculation of diluted net loss per share when their effect is dilutive. Basic and diluted loss per share are calculated as follows (in thousands, except share and per share data):


	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Numerator:
Net loss	$	(20,724	)	$	(29,031	)	$	(74,453	)	$	(81,113	)

Denominator:
Weighted average common shares outstanding - basic and diluted		47,464,310			44,935,126			47,404,039			37,706,045

Net loss per share - basic and diluted	$	(0.44	)	$	(0.65	)	$	(1.57	)	$	(2.15	)

For the three and nine months ended September 30, 2017, the total number of securities that could potentially dilute basic net loss per share in the future that were not included in the computation of diluted net loss per share because the effect would have been antidilutive was 7.0 million and 6.6 million, respectively. For the three and nine months ended September 30, 2016, the total number of securities that could potentially dilute basic net loss per share in the future that were not included in the computation of diluted net loss per share because the effect would have been antidilutive was 4.7 million and 4.6 million, respectively.

Accrued and Other Liabilities

9 Months Ended

Sep. 30, 2017

Payables and Accruals [Abstract]

Accrued and Other Liabilities

NOTE 7. ACCRUED AND OTHER LIABILITIES

Accrued liabilities and other liabilities consist of the following (in thousands):


	September 30,		December 31,
	2017		2016
Accrued clinical and non-clinical expenses	$	6,926	$	6,694
Accrued contract manufacturing		2,895		2,705
Accrued professional and consulting services		761		322
Other		700		684

	$	11,282	$	10,405

Stockholders' Equity	9 Months Ended
Stockholders' Equity	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	NOTE 8. STOCKHOLDERS’ EQUITY *Option Exercises* For the three and nine months ended September 30, 2017, employees exercised options to purchase 4,833 and 33,159 shares, respectively, of the Company’s common stock, with insignificant net proceeds in the three months ended September 30, 2017, and net proceeds to the Company of approximately $0.1 million in the nine months ended September 30, 2017. *Restricted Stock Units* For the three and nine months ended September 30, 2017, the Company issued zero and 15,188 shares, respectively, of its common stock upon vesting of restricted stock units. *Employee Stock Purchase Plan* In February 2017, the Company sold 42,845 shares under the ESPP. The shares were purchased at a purchase price of $8.77 per share with proceeds to the Company of approximately $0.4 million. In August 2017, the Company sold 56,498 shares under the ESPP. The shares were purchased at a purchase price of $4.38 per share with proceeds to the Company of approximately $0.2 million. *Issuance of Common Stock for Services* For the three and nine months ended September 30, 2017, the Company issued zero and 46,858 shares, respectively, of its common stock in exchange for services performed. The shares issued for the nine months ended September 30, 2017, were valued at $0.2 million based on the fair value of the common stock on the date of grant.

Contingencies	9 Months Ended
Contingencies	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Contingencies	NOTE 9. CONTINGENCIES From time to time the Company may be involved in claims arising in connection with its business. Based on information currently available, the Company believes that the amount, or range, of reasonably possible losses in connection with any pending actions against it in excess of established reserves, in the aggregate, not to be material to its consolidated financial condition or cash flows. However, losses may be material to the Company’s operating results for any particular future period, depending on the level of income or loss for such period.

Restructuring	9 Months Ended
Restructuring	Sep. 30, 2017
Restructuring and Related Activities [Abstract]
Restructuring	NOTE 10. RESTRUCTURING In August 2017, the Company announced a corporate restructuring plan that included a significant reduction in its workforce. As a result, the Company recorded one-time charges for employee severance benefits in the three months ended September 30, 2017, for which $0.6 million was included in research and development expenses and $0.3 million in general and administrative expenses in the Statement of Operations. Substantially all of the $0.9 million had been paid as of September 30, 2017.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2017

Accounting Policies [Abstract]

Use of Estimates

Use of Estimates

Accrued Research and Development Expenses

Accrued Research and Development Expenses

•

contract research organizations (“CROs”) in connection with clinical studies;

•

investigative sites in connection with clinical studies;

•

vendors related to product manufacturing, development and distribution of clinical supplies; and

•

vendors in connection with preclinical development activities.

Reclassification

Reclassification

Recent Accounting Pronouncements

Recent Accounting Pronouncements

Fair Value Measurements

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 and readily accessible by the Company at the reporting date. 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 Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Examples of assets and liabilities utilizing Level 2 inputs are corporate bonds, commercial paper, certificates of deposit and over-the-counter derivatives.

Level 3	–	Valuations based on unobservable inputs in which there is little or no market data, which require the Company to develop its own assumptions.

Cash, Cash Equivalents and Investments (Tables)

9 Months Ended

Sep. 30, 2017

Cash and Cash Equivalents [Abstract]

Schedule of Securities Classified as Cash, Cash Equivalents and Short-term Investments


	September 30, 2017
	Amortized Cost		Gross Unrealized					Fair Value
	Amortized Cost		Gains		Losses			Fair Value
Cash and cash equivalents:
Cash	$	7,254	$	—	$	—		$	7,254
Money market funds		44,155		—		—			44,155
U.S. treasury securities		1,799		—		—			1,799
U.S. government-sponsored agency bonds		1,800		—		—			1,800
Corporate bonds		2,246		—		—			2,246
Commercial paper		2,200		—		—			2,200

Total cash and cash equivalents		59,454		—		—			59,454

Short-term investments
U.S. treasury securities		2,988		—		—			2,988
Corporate bonds		38,247		1		(9	)		38,239
Commercial paper		21,382		1		(3	)		21,380
Asset-backed securities		7,227		1		(1	)		7,227

Total short-term investments		69,844		3		(13	)		69,834

Total cash equivalents and investments	$	129,298	$	3	$	(13	)	$	129,288


	December 31, 2016
	Amortized Cost		Gross Unrealized					Fair Value
	Amortized Cost		Gains		Losses			Fair Value
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 cash equivalents and investments	$	200,894	$	7	$	(78	)	$	200,823

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

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 (in thousands):


	September 30, 2017
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds	$	44,155	$	44,155	$	—	$	—
U.S. treasury securities		4,787		4,787		—		—
U.S. government-sponsored agency bonds		1,800		1,800		—		—
Corporate bonds		40,485		—		40,485		—
Commercial paper		23,580		—		23,580		—
Asset-backed securities		7,227		—		7,227		—

Total	$	122,034	$	50,742	$	71,292	$	—


	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	$	—

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

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

Summary of Stock-Based Compensation Recognized


	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Research and development	$	916	$	685	$	3,361	$	1,992
General and administrative		1,186		606		3,640		1,775

Total	$	2,102	$	1,291	$	7,001	$	3,767

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Computation of Basic and Diluted Loss Per Share Attributable to Common Stockholders

Basic and diluted loss per share are calculated as follows (in thousands, except share and per share data):


	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Numerator:
Net loss	$	(20,724	)	$	(29,031	)	$	(74,453	)	$	(81,113	)

Denominator:
Weighted average common shares outstanding - basic and diluted		47,464,310			44,935,126			47,404,039			37,706,045

Net loss per share - basic and diluted	$	(0.44	)	$	(0.65	)	$	(1.57	)	$	(2.15	)

Accrued and Other Liabilities (Tables)

9 Months Ended

Sep. 30, 2017

Payables and Accruals [Abstract]

Schedule of Accrued Liabilities and Other Liabilities

Accrued liabilities and other liabilities consist of the following (in thousands):


	September 30,		December 31,
	2017		2016
Accrued clinical and non-clinical expenses	$	6,926	$	6,694
Accrued contract manufacturing		2,895		2,705
Accrued professional and consulting services		761		322
Other		700		684

	$	11,282	$	10,405

Organization and Basis of Presentation - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017 Segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments	1

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Accounting Policies [Abstract]
Issuance of common stock for services	$ 202	$ 187

Cash Equivalents and Investments - Schedule of Securities Classified as Cash, Cash Equivalents and Short-term Investments (Detail) - USD ($)
$ in Thousands

Sep. 30, 2017

Dec. 31, 2016

Sep. 30, 2016

Dec. 31, 2015

Cash Cash Equivalents And Short Term Investments [Line Items]

Cash and cash equivalents, Amortized Cost

$ 59,454

$ 74,598

^[1]

$ 160,360

$ 107,004

Cash and cash equivalents, Gross Unrealized Gains

Cash and cash equivalents, Gross Unrealized Losses

Cash and cash equivalents, Fair Value

59,454

74,598

Short-term investments, Amortized Cost

69,844

126,296

Short-term investments, Gross Unrealized Gains

Short-term investments, Gross Unrealized Losses

(13)

(78)

Short-term investments, Fair Value

69,834

126,225

Cash equivalents and short-term investments, Amortized Cost

129,298

200,894

Cash equivalents and short-term investments, Gross Unrealized Gains

Cash equivalents and short-term investments, Gross Unrealized Losses

(13)

(78)

Cash equivalents and short-term investments, Fair Value

129,288

200,823

Cash [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Cash and cash equivalents, Amortized Cost

7,254

3,638

Cash and cash equivalents, Gross Unrealized Gains

Cash and cash equivalents, Gross Unrealized Losses

Cash and cash equivalents, Fair Value

7,254

3,638

Money Market Funds [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Cash and cash equivalents, Amortized Cost

44,155

68,561

Cash and cash equivalents, Gross Unrealized Gains

Cash and cash equivalents, Gross Unrealized Losses

Cash and cash equivalents, Fair Value

44,155

68,561

U.S. Treasury Securities [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Cash and cash equivalents, Amortized Cost

1,799

Cash and cash equivalents, Gross Unrealized Gains

Cash and cash equivalents, Gross Unrealized Losses

Cash and cash equivalents, Fair Value

1,799

U.S. Government Sponsored Agency Bonds [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Cash and cash equivalents, Amortized Cost

1,800

Cash and cash equivalents, Gross Unrealized Gains

Cash and cash equivalents, Gross Unrealized Losses

Cash and cash equivalents, Fair Value

1,800

Corporate Bonds [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Cash and cash equivalents, Amortized Cost

2,246

Cash and cash equivalents, Gross Unrealized Gains

Cash and cash equivalents, Gross Unrealized Losses

Cash and cash equivalents, Fair Value

2,246

Commercial Paper (Cash Equivalents) [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Cash and cash equivalents, Amortized Cost

2,200

2,399

Cash and cash equivalents, Gross Unrealized Gains

Cash and cash equivalents, Gross Unrealized Losses

Cash and cash equivalents, Fair Value

2,200

2,399

U.S. Treasury Securities [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Short-term investments, Amortized Cost

2,988

Short-term investments, Fair Value

2,988

Corporate Bonds [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Short-term investments, Amortized Cost

38,247

58,464

Short-term investments, Gross Unrealized Gains

Short-term investments, Gross Unrealized Losses

(9)

(56)

Short-term investments, Fair Value

38,239

58,410

Commercial Paper (Investments) [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Short-term investments, Amortized Cost

21,382

62,946

Short-term investments, Gross Unrealized Gains

Short-term investments, Gross Unrealized Losses

(3)

(20)

Short-term investments, Fair Value

21,380

62,931

Asset-Backed Securities [Member]

Cash Cash Equivalents And Short Term Investments [Line Items]

Short-term investments, Amortized Cost

7,227

4,886

Short-term investments, Gross Unrealized Gains

Short-term investments, Gross Unrealized Losses

(1)

(2)

Short-term investments, Fair Value

$ 7,227

$ 4,884

[1]	Derived from the audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2016.

Cash Equivalents and Investments - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017 USD ($)
Cash Cash Equivalents And Short Term Investments [Line Items]
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 - Summary of Fair Value Measurements of Company's Financial Assets (Detail) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Assets at fair value	$ 122,034	$ 197,185
Level 1 [Member]
Assets:
Assets at fair value	50,742	68,561
Level 2 [Member]
Assets:
Assets at fair value	71,292	128,624
Money Market Funds [Member]
Assets:
Assets at fair value	44,155	68,561
Money Market Funds [Member] \| Level 1 [Member]
Assets:
Assets at fair value	44,155	68,561
U.S. Treasury Securities [Member]
Assets:
Assets at fair value	4,787
U.S. Treasury Securities [Member] \| Level 1 [Member]
Assets:
Assets at fair value	4,787
U.S. Government Sponsored Agency Bonds [Member]
Assets:
Assets at fair value	1,800
U.S. Government Sponsored Agency Bonds [Member] \| Level 1 [Member]
Assets:
Assets at fair value	1,800
Corporate Bonds [Member]
Assets:
Assets at fair value	40,485	58,410
Corporate Bonds [Member] \| Level 2 [Member]
Assets:
Assets at fair value	40,485	58,410
Commercial Paper [Member]
Assets:
Assets at fair value	23,580	65,330
Commercial Paper [Member] \| Level 2 [Member]
Assets:
Assets at fair value	23,580	65,330
Asset-Backed Securities [Member]
Assets:
Assets at fair value	7,227	4,884
Asset-Backed Securities [Member] \| Level 2 [Member]
Assets:
Assets at fair value	$ 7,227	$ 4,884

Fair Value Measurements - Additional Information (Detail)	Sep. 30, 2017 USD ($)
Fair Value Disclosures [Abstract]
Transfer of assets from Level 1 to Level 2	$ 0
Transfer of assets from Level 2 to Level 1	$ 0

Stock-Based Compensation - Summary of Stock-Based Compensation Expense Recognized (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	$ 2,102	$ 1,291	$ 7,001	$ 3,767
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	916	685	3,361	1,992
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation	$ 1,186	$ 606	$ 3,640	$ 1,775

Stock-Based Compensation - Additional Information (Detail) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017 USD ($) shares	Sep. 30, 2017 USD ($) shares
Options to Purchase Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock based compensation expense	$ 15.5	$ 15.5
Unrecognized stock based compensation expense, weighted-average remaining recognition period		2 years 7 months 6 days
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock based compensation expense	$ 2.8	$ 2.8
Unrecognized stock based compensation expense, weighted-average remaining recognition period		1 year 10 months 25 days
Performance-Based Restricted Stock Units (PSRUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of vested shares \| shares	0	0
Recognized stock-based compensation related expense in connection with vesting of award granted	$ 0.1	$ 0.7
Unrecognized stock based compensation expense	1.1	$ 1.1
Unrecognized stock based compensation expense, weighted-average remaining recognition period		1 year 1 month 6 days
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock based compensation expense	$ 0.1	$ 0.1
Unrecognized stock based compensation expense, weighted-average remaining recognition period		4 months 24 days

Net Loss Per Share - Computation of Basic and Diluted Loss Per Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net loss	$ (20,724)	$ (29,031)	$ (74,453)	$ (81,113)
Denominator:
Weighted average common shares outstanding - basic and diluted	47,464,310	44,935,126	47,404,039	37,706,045
Net loss per share - basic and diluted	$ (0.44)	$ (0.65)	$ (1.57)	$ (2.15)

Net Loss Per Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Anti-dilutive securities excluded from computation of diluted net loss per share attributable to common stockholders	7.0	4.7	6.6	4.6

Accrued and Other Liabilities - Schedule of Accrued Liabilities and Other Liabilities (Detail) - USD ($)
$ in Thousands

Sep. 30, 2017

Dec. 31, 2016

Payables and Accruals [Abstract]

Accrued clinical and non-clinical expenses

$ 6,926

$ 6,694

Accrued contract manufacturing

2,895

2,705

Accrued professional and consulting services

761

322

Other

700

684

Accrued liabilities and other liabilities

$ 11,282

$ 10,405

^[1]

[1]	Derived from the audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2016.

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended	9 Months Ended
	Aug. 31, 2017	Feb. 28, 2017	Sep. 30, 2017	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock for services (Shares)			0	46,858
Issuance of common stock for services, amount				$ 0.2
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares sold under ESPP	56,498	42,845
Purchase price of common shares	$ 4.38	$ 8.77
Proceeds from issuance of shares under the ESPP	$ 0.2	$ 0.4
Options to Purchase Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchased by employees on exercise of options			4,833	33,159
Proceeds from exercise of stock options				$ 0.1
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares issued due to RSUs vesting			0	15,188

Restructuring - Additional Information (Detail) - One-time Termination Benefits [Member] $ in Millions	3 Months Ended
	Sep. 30, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Cash payments	$ 0.9
Research and Development [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance benefits	0.6
General and Administrative [Member]
Restructuring Cost and Reserve [Line Items]
Employee severance benefits	$ 0.3