Eledon Pharmaceuticals (ELDN) 10-K 3 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Jan. 31, 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	TKAI
Entity Registrant Name	TOKAI PHARMACEUTICALS INC
Entity Central Index Key	1,404,281
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		22,641,651
Entity Public Float			$ 53,968,136

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 23,223	$ 24,023
Marketable securities	4,175	39,934
Restricted cash	150
Prepaid expenses and other current assets	1,995	3,213
Total current assets	29,543	67,170
Property and equipment, net	98	489
Restricted cash	120	270
Other assets		45
Total assets	29,761	67,974
Current liabilities:
Accounts payable	430	1,208
Accrued expenses	2,389	4,954
Total current liabilities	2,819	6,162
Long-term liabilities	84	88
Total liabilities	2,903	6,250
Commitments and contingencies (Note 9)
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.001 par value; 200,000,000 shares authorized; 22,641,651 and 22,597,144 shares issued and outstanding at December 31, 2016 and December 31, 2015, respectively	23	23
Additional paid-in capital	196,233	193,194
Accumulated other comprehensive loss	(1)	(55)
Accumulated deficit	(169,397)	(131,438)
Total stockholders' equity	26,858	61,724
Total liabilities and stockholders' equity	$ 29,761	$ 67,974

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
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	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	22,641,651	22,597,144
Common stock, shares outstanding	22,641,651	22,597,144

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Revenue	$ 0	$ 0	$ 0
Operating expenses:
Research and development	25,024	32,638	14,577
General and administrative	13,099	12,623	8,885
Total operating expenses	38,123	45,261	23,462
Loss from operations	(38,123)	(45,261)	(23,462)
Interest and other income, net	164	174	166
Net loss	$ (37,959)	$ (45,087)	$ (23,296)
Net loss per share, basic and diluted	$ (1.68)	$ (2.01)	$ (3.60)
Weighted average common shares outstanding, basic and diluted	22,634,641	22,484,343	6,469,289
Comprehensive loss:
Net loss	$ (37,959)	$ (45,087)	$ (23,296)
Other comprehensive income (loss):
Unrealized gains (losses) on marketable securities	54	(55)
Total other comprehensive income (loss)	54	(55)
Total comprehensive loss	$ (37,905)	$ (45,142)	$ (23,296)

Statements of Changes in Redeem

Statements of Changes in Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	IPO [Member]	Series A, B-1, B-2, C,D-1, D-2, D-3 and E Redeemable Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member]IPO [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]IPO [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2013	$ (55,267)					$ 7,788			$ (63,055)
Beginning Balance at Dec. 31, 2013			$ 85,345
Beginning Balance, Shares at Dec. 31, 2013				493,292
Beginning Balance, Shares at Dec. 31, 2013			155,586,141
Issuance of common stock upon exercise of stock options	16					16
Issuance of common stock upon exercise of stock options, Shares				8,875
Stock-based compensation expense	2,108					2,108
Conversion of preferred stock to common stock	85,345		$ (85,345)	$ 15		85,330
Conversion of preferred stock to common stock, Shares			(155,586,141)	14,860,173
Issuance of common stock upon initial public offering		$ 97,929			$ 7		$ 97,922
Issuance of common stock upon initial public offering, Shares					7,020,000
Issuance costs	(3,334)					(3,334)
Net loss	(23,296)								(23,296)
Ending Balance at Dec. 31, 2014	103,501			$ 22		189,830			(86,351)
Ending Balance, Shares at Dec. 31, 2014				22,382,340
Issuance of common stock upon exercise of stock options	464			$ 1		463
Issuance of common stock upon exercise of stock options, Shares				201,153
Issuance of common stock upon vesting of restricted stock units	0		$ 0	$ 0		0		$ 0	0
Issuance of common stock upon vesting of restricted stock units, Shares				13,651
Stock-based compensation expense	2,901					2,901
Unrealized gain (loss) on marketable securities	(55)							(55)
Net loss	(45,087)								(45,087)
Ending Balance at Dec. 31, 2015	61,724			$ 23		193,194		(55)	(131,438)
Ending Balance, Shares at Dec. 31, 2015				22,597,144
Issuance of common stock upon exercise of stock options	$ 37					37
Issuance of common stock upon exercise of stock options, Shares	30,856			30,856
Issuance of common stock upon vesting of restricted stock units	$ 0		$ 0	$ 0		0		0	0
Issuance of common stock upon vesting of restricted stock units, Shares				13,651
Stock-based compensation expense	3,002					3,002
Unrealized gain (loss) on marketable securities	54							54
Net loss	(37,959)								(37,959)
Ending Balance at Dec. 31, 2016	$ 26,858			$ 23		$ 196,233		$ (1)	$ (169,397)
Ending Balance, Shares at Dec. 31, 2016				22,641,651

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net loss	$ (37,959)	$ (45,087)	$ (23,296)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	3,002	2,901	2,108
Depreciation expense	171	109	21
Impairment of property and equipment	237
Release of reserve for loan to former advisor		(49)	(158)
Premium on purchase of marketable securities	(2)	(186)
Amortization of premium on marketable securities	115	72
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,263	(958)	(1,830)
Accounts payable	(778)	443	760
Accrued expenses	(2,565)	1,476	1,274
Other assets		(45)
Other long-term liabilities	(4)	88
Net cash used in operating activities	(36,520)	(41,236)	(21,121)
Cash flows from investing activities:
Proceeds from maturities of marketable securities	36,200
Purchases of marketable securities	(500)	(39,875)
Purchases of property and equipment	(17)	(565)	(25)
Change in restricted cash		(70)	(150)
Net cash provided by (used in) investing activities	35,683	(40,510)	(175)
Cash flows from financing activities:
Proceeds from exercise of common stock options	37	464	16
Repayment of notes receivable		49	158
Proceeds from initial public offering, net of underwriting discounts and commissions			97,929
Payments of initial public offering costs			(3,304)
Net cash provided by financing activities	37	513	94,799
Net increase (decrease) in cash and cash equivalents	(800)	(81,233)	73,503
Cash and cash equivalents at beginning of period	24,023	105,256	31,753
Cash and cash equivalents at end of period	$ 23,223	$ 24,023	105,256
Supplemental disclosure of non-cash investing activities:
Conversion of redeemable convertible preferred stock to common stock			$ (85,345)

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation Tokai Pharmaceuticals, Inc. (the “Company”) was incorporated on March 26, 2004 under the laws of the State of Delaware. The Company is a biopharmaceutical company focused on developing and commercializing innovative therapies for the treatment of prostate cancer and other hormonally-driven diseases. The Company has focused substantially all of its research and development efforts on the development of galeterone, an oral small molecule, including clinical trials of galeterone for the treatment of patients with metastatic castration-resistant prostate cancer, or mCRPC. The Company also has a drug discovery program, known as ARDA (androgen receptor degradation agents), under which it identified novel compounds for patients with androgen receptor signaling diseases, including prostate cancer. In July 2016, the Company announced its plan to discontinue the ARMOR3-SV, ® treatment-naïve AR-V7 ARMOR3-SV AR-V7 ARMOR3-SV ARMOR3-SV In addition, in August 2016, the Company determined to discontinue enrollment in its Phase 2 ARMOR2 expansion clinical trial of galeterone in mCRPC patients with acquired resistance to Xtandi and not to proceed with its planned study of galeterone in mCRPC patients who rapidly progress on either enzalutamide or Zytiga ® In September 2016, the Company announced that the board of directors had initiated a review of strategic alternatives that could result in changes to its business strategy and future operations. The objective of this review, which is being conducted in parallel with the review of development options for galeterone and the ARDA program, was to maximize shareholder value. On December 21, 2016, the Company entered into a Share Purchase Agreement (the “Share Purchase Agreement”) with Otic Pharma, Ltd., a private limited company organized under the laws of the State of Israel (“Otic”) and the shareholders of Otic (the “Selling Shareholders”) pursuant to which, among other things, each Selling Shareholder agreed to sell to the Company, and the Company agreed to purchase from each Selling Shareholder, all of the ordinary and preferred shares of Otic (the “Otic Shares”) owned by such Selling Shareholder (the “Otic Transaction”). See “Note 13. Share Purchase Agreement” for further information regarding the Otic Transaction. The Company amended and restated the Share Purchase Agreement on March 2, 2017 to update the allocation of shares of the Company’s common stock among the Selling Shareholders and to extend to May 31, 2017, the date after which the Company or Otic may terminate the Share Purchase Agreement. The Company is subject to risks common to companies in the biotechnology industry including, but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing. Galeterone and any product candidates that the Company may seek to develop in the future under the ARDA program or otherwise, will require significant additional research and development efforts, including extensive preclinical and clinical testing, formulation development and manufacturing, and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure, and extensive compliance capabilities. There can be no assurance that the Company’s research and development activities will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained or maintained, that any products developed will obtain necessary regulatory approval or that any approved products will be commercially viable. Even if the Company’s drug development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees, consultants and contracted service providers. The Company’s financial statements have been prepared on the basis of continuity of operations, realization of assets and satisfaction of liabilities in the ordinary course of business. The Company has incurred losses and negative cash flows from operations since inception. As of December 31, 2016, the Company had an accumulated deficit of $169,397 and had cash and investments of $27,398. In light of the discontinuation of the ARMOR3-SV

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 Use of Estimates The preparation of financial statements in conformity with U.S. Generally Accepted Accounting Principles (“GAAP”) requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting periods. Significant estimates, assumptions and judgments reflected in these financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates. Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of ninety days or less at date of purchase to be cash equivalents. Cash equivalents, which consist of money market accounts, are stated at fair value. Marketable Securities The Company’s marketable securities are classified as available-for-sale Concentration of Risk Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents and marketable securities. The Company has all cash and cash equivalents and marketable securities’ balances at two accredited financial institutions, in amounts that exceed federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company is dependent on third-party manufacturers to supply products for research and development activities in its programs. In particular, the Company relies and expects to continue to rely on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs. Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. 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. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices) such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method based upon estimated useful lives as follows: Years Lab equipment 3 Computer equipment 3 Furniture and fixtures 5 Leasehold improvements Shorter of life of lease or estimated useful life Upon retirement or sale of property and equipment, the cost and related accumulated depreciation of such property and equipment disposed of are removed from the accounts and any resulting gain or loss is included in loss from operations. Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends, and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows. During the year ended December 31, 2016, the Company recorded an impairment loss of $237 related to property and equipment, including lab equipment which will no longer be used as a result of the discontinuation of the ARMOR3-SV Research and Development Costs Research and development costs are expensed as incurred. Included in research and development expenses are salaries, stock-based compensation and benefits of employees, third-party license fees and other operational costs related to the Company’s research and development activities, including manufacturing expenses and external costs of outside vendors engaged to conduct both preclinical studies and clinical trials. The Company expenses raw materials used to manufacture its drug substance when received. As part of the process of preparing financial statements, the Company is required to estimate its accrued research and development expenses. This process involves reviewing open contracts and purchase orders, communicating with company personnel and outside vendors to identify services that have been performed on the Company’s behalf and estimating the level of service performed and the associated costs incurred for the services when the Company has not yet been invoiced or otherwise notified of the actual costs. The majority of the Company’s service providers invoice in arrears for services performed, on a pre-determined • clinical research organizations in connection with clinical trials; • investigative sites or other providers in connection with clinical trials; • Qiagen in connection with the development of the AR-V7 • vendors in connection with preclinical development activities; and • vendors related to product manufacturing, development and distribution of clinical supplies. The Company bases its expenses related to clinical trials on its estimates of the services received and efforts expended pursuant to contracts with multiple clinical research organizations and investigative sites that manage and conduct clinical trials on the Company’s 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 vendors will exceed the level of services provided and result in a prepayment of the clinical expense. Payments under some of these contracts depend on factors such as the successful enrollment of patients 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 patients, 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 its estimate, the Company adjusts the accrual or amount of prepaid expense accordingly. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low in any particular period. For the years ended December 31, 2016, 2015 and 2014, the Company has not made any material adjustments to its prior estimates of accrued research and development expenses. Patent Costs All patent-related costs incurred in connection with filing and prosecuting patent applications are recorded as general and administrative expenses as incurred, as recoverability of such expenditures is uncertain. Accounting for Stock-Based Compensation The Company measures all stock options and other stock-based awards granted to employees and directors at the fair value on the date of the grant using the Black-Scholes option-pricing model. The fair value of the awards is recognized as expense, net of estimated forfeitures, over the requisite service period, which is generally the vesting period of the respective award. The straight-line method of expense recognition is applied to all awards with service-only conditions, while the graded vesting method is applied to all grants with both service and performance conditions. For stock-based awards granted to non-employees, non-employees re-measured The Company classifies stock-based compensation expense in its statement of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. The Company recognizes compensation expense for only the portion of awards that are expected to vest. In developing a forfeiture rate estimate, the Company has considered its historical experience to estimate pre-vesting Income Taxes The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the financial statements or in the Company’s tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. The Company accounts for uncertainty in income taxes recognized in its financial statements by applying a two-step Segment Data The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company’s singular focus is on developing novel proprietary therapies for the treatment of prostate cancer and other hormonally-driven diseases. No revenue has been generated since inception. All of the Company’s assets are located in the United States. Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2016 and 2015, the Company’s only element of other comprehensive loss was unrealized gains (losses) on marketable securities. For the year ended December 31, 2014, there was no difference between net loss and comprehensive loss. Net Income (Loss) Per Share Basic net income (loss) per share is computed by dividing the net income (loss) the weighted average number of common shares outstanding for the period. Diluted net income (loss) per share is computed by dividing the diluted net income (loss) by the weighted average number of common shares, including potential dilutive common shares assuming the dilutive effect of outstanding stock options and unvested restricted common shares, as determined using the treasury stock method. For periods in which the Company has reported net losses, diluted net loss per common share is the same as basic net loss per common share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The following common stock equivalents outstanding as of December 31, 2016, 2015 and 2014 were excluded from the computation of diluted net loss per share for the years ended December 31, 2016, 2015 and 2014, because they had an anti-dilutive impact: December 31, 2016 2015 2014 Stock options to purchase common stock 1,896,169 2,861,011 2,146,927 Unvested restricted common stock units — 40,953 54,604 1,896,169 2,901,964 2,201,531 Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases 2016-02”), 2016-02 In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation 2016-09”). 2016-09 2016-09 In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows: Restricted Cash 2016-18”). 2016-18 2016-18

Marketable Securities and Fair

Marketable Securities and Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Marketable Securities and Fair Value Measurements	3. Marketable Securities and Fair Value Measurements As of December 31, 2016, marketable securities by security type consisted of: Amortized Gross Gross Estimated Certificates of Deposit (due within one year) $ 1,175 $ — $ — $ 1,175 United States Treasury Notes (due within one year) 3,001 — (1 ) 3,000 Total $ 4,176 $ — $ (1 ) $ 4,175 As of December 31, 2015, marketable securities by security type consisted of: Amortized Gross Gross Estimated Certificates of Deposit (due within one year) $ 13,709 $ — $ — $ 13,709 Certificates of Deposit (due after one year through two years) 1,178 — — 1,178 United States Treasury Notes (due within one year) 22,596 — (47 ) 22,549 United States Treasury Notes (due after one year through two years) 2,506 — (8 ) 2,498 Total $ 39,989 $ — $ (55 ) $ 39,934 The following tables present the Company’s fair value hierarchy for its cash equivalents and marketable securities, which are measured at fair value on a recurring basis as of December 31, 2016 and 2015: Fair Value Measurements at December 31, 2016 Using Level 1 Level 2 Level 3 Total Cash equivalents: Money Market Instruments $ — $ 17,748 $ — $ 17,748 Marketable securities: Certificates of Deposit — 1,175 — 1,175 United States Treasury Notes — 3,000 — 3,000 Total $ — $ 21,923 $ — $ 21,923 Fair Value Measurements at December 31, 2015 Level 1 Level 2 Level 3 Total Cash equivalents: Money Market Instruments $ — $ 18,361 $ — $ 18,361 Marketable securities: Certificates of Deposit — 14,887 — 14,887 United States Treasury Notes — 25,047 — 25,047 Total $ — $ 58,295 $ — $ 58,295 The carrying values of accounts payable and accrued expenses approximate their fair value due to the short-term

Property and Equipment, net

Property and Equipment, net	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property and Equipment, net	4. Property and Equipment, net Property and equipment, net consisted of the following as of December 31, 2016 and 2015: December 31, 2016 2015 Computer equipment $ 162 $ 243 Leasehold improvements 66 66 Lab equipment — 322 Furniture and fixtures — 23 228 654 Less: Accumulated depreciation (130 ) (165 ) $ 98 $ 489 Depreciation expense was $171, $109 and $21 for the years ended December 31, 2016, 2015 and 2014, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consisted of the following as of December 31, 2016 and 2015: December 31, 2016 2015 Accrued research and development expenses $ 907 $ 3,188 Accrued professional fees 871 699 Accrued payroll and related expenses 394 900 Accrued other 217 167 $ 2,389 $ 4,954

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Redeemable Convertible Preferred Stock	6. Redeemable Convertible Preferred Stock Prior to the completion of its initial public offering (“IPO”) in September 2014 (Note 7), the Company had outstanding Series A, Series B-1, B-2, D-1, D-2, D-3 10.47-for-1

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Common Stock	7. Common Stock On August 29, 2014, the Company effected a 1-for-10.47 On September 22, 2014, the Company completed an IPO of its common stock through the issuance and sale of 6,480,000 shares of common stock at a price to the public of $15.00 per share, resulting in net proceeds of $87,062 after deducting underwriting discounts and commissions and offering expenses. Upon the closing of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock automatically converted into 14,860,173 shares of the Company’s common stock. On October 9, 2014, the Company issued and sold an additional 540,000 shares of its common stock at the public offering price of $15.00 per share as a result of the partial exercise by the underwriters of their option to purchase additional shares of common stock, resulting in additional net proceeds to the Company of $7,533 after deducting underwriting discounts and commissions. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are not entitled to receive dividends, unless declared by the board of directors.

Stock-Based Awards

Stock-Based Awards	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Awards	8. Stock-Based Awards The Company’s 2014 Stock Incentive Plan (the “2014 Plan”) permits the Company to make grants of incentive stock options, non-statutory As required by the 2007 Plan and 2014 Plan, the exercise price for stock options granted is not to be less than the fair value of common stock as of the date of grant. The Company bases fair value of common stock on the quoted market price. Prior to the IPO, the value of common stock was determined by the Company’s board of directors by taking into consideration its most recently available valuation of common stock performed by management and the board of directors as well as additional factors which might have changed since the date of the most recent contemporaneous valuation through the date of grant. During the years ended December 31, 2016, 2015 and 2014, the Company granted options to purchase 324,900, 996,845 and 1,039,155 shares of common stock, respectively, to certain employees, consultants and directors. The vesting of most of these awards is time-based and the restrictions typically lapse over three to four years. 2014 Employee Stock Purchase Plan Under the 2014 Employee Stock Purchase Plan (the “ESPP”), an aggregate of 225,000 shares of the Company’s common stock are reserved for issuance. The number of shares of the Company’s common stock reserved for issuance under the ESPP will automatically increase on the first day of each fiscal year equal to the lesser of (1) 450,000 shares of the Company’s common stock, (2) 1% of the total number of shares of the Company’s common stock outstanding on the first day of the applicable fiscal year and (3) an amount determined by the Company’s board of directors. No offering periods have commenced under the ESPP. The number of shares reserved for issuance under the ESPP was increased by 226,416 shares effective as of January 1, 2017. Stock Option Valuation The fair value of each stock option grant is estimated on the date of grant using the Black-Scholes option-pricing model. Prior to its IPO, the Company was a private company and lacked company-specific historical and implied volatility information. Therefore, the Company estimated its expected stock volatility based on the historical volatility of a publicly traded group of peer companies. The Company expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The expected term of stock options granted to non-employees The following table sets forth the assumptions that the Company used to determine the fair value of the stock options granted, presented on a weighted average basis: Year Ended December 31, 2016 2015 2014 Risk-free interest rate 1.52 % 1.79 % 1.83 % Expected term (in years) 5.91 6.01 5.95 Expected volatility 74.7 % 74.2 % 79.4 % Expected dividend yield 0 % 0 % 0 % The following table summarizes the Company’s stock option activity from January 1, 2016 through December 31, 2016: Shares Issuable Weighted Weighted Aggregate (In years) Outstanding as of December 31, 2015 2,861,011 $ 7.57 8.3 $ 7,906 Granted 324,900 6.17 Exercised (30,856 ) 1.18 Forfeited (1,258,886 ) 8.90 Outstanding as of December 31, 2016 1,896,169 $ 6.55 6.1 $ 13 Options vested and expected to vest as of December 31, 2016 1,889,406 $ 6.53 6.1 $ 13 Options exercisable as of December 31, 2016 1,434,904 $ 5.58 5.4 $ 13 The aggregate intrinsic value was calculated based on the positive differences between the market value of the Company’s common stock on December 31, 2016 and 2015, of $0.98 and $8.72 per share, respectively, and the exercise prices of the options. The weighted average grant date fair value of stock options granted was $4.02, $6.94 and $6.70 per share for the years ended December 31, 2016, 2015 and 2014, respectively. The total intrinsic value of stock options exercised was $144, $2,236 and $35 for the years ended December 31, 2016, 2015 and 2014, respectively. Restricted Common Stock Units The 2014 Plan provides for the award of restricted common stock units. The Company has granted restricted common stock units with time-based vesting conditions. Unvested shares of restricted common stock may not be sold or transferred by the holder. These restrictions lapse according to the time-based vesting conditions of each award. The table below summarizes the Company’s restricted stock unit activity from January 1, 2016 through December 31, 2016: Shares Weighted Unvested restricted common stock units as of December 31, 2015 40,953 $ 15.00 Issued — — Vested (13,651 ) 15.00 Forfeited (27,302 ) 15.00 Unvested restricted common stock units as of December 31, 2016 — During 2014, the Company granted 54,604 restricted stock units with a fair value of $15.00 per share that were subject to time-based vesting conditions that lapse over four years. Upon vesting, the restricted stock units entitle the holder to one share of common stock for each restricted stock unit. All restricted stock units currently granted had been classified as equity instruments as their terms require settlement in shares. Restricted stock units with time-based vesting conditions are valued on the grant date using the grant date market price of the underlying shares. The Company did not grant restricted stock units in 2016 or 2015. Stock-based Compensation The Company recorded stock-based compensation expense related to stock options and restricted common stock units in the following expense categories of its statements of operations: Year Ended December 31, 2016 2015 2014 Research and development $ 526 $ 634 $ 552 General and administrative 2,476 2,267 1,556 $ 3,002 $ 2,901 $ 2,108 Stock-based compensation expense for the year ended December 31, 2014 includes $880 of stock-based compensation expense related to a performance-based option grant which vested during 2014. As of December 31, 2016, the Company had an aggregate of $2,675 of unrecognized stock-based compensation expense, which it expects to recognize over a weighted average period of 2.2 years.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Leases In February 2015, the Company entered into a sublease with a Massachusetts limited liability company (the “Sublandlord”) for 15,981 square feet of office space in Boston, Massachusetts. The sublease was subject and subordinate to a prime lease between the Sublandlord and the prime landlord. The term of the sublease commenced on April 1, 2015 and expired on December 31, 2016. In June 2015, the Company entered into a lease (the “New Lease”) for the existing space with the prime landlord (the “Landlord”), which effectively extends the term until July 31, 2018. Payment escalations specified in the lease agreements are accrued such that rent expense per square foot is recognized on a straight-line basis over the terms of occupancy. Prior to April 2015, the Company leased office space in Cambridge, Massachusetts, and obtained certain office-related services on a month-to-month 30-day During the years ended December 31 2016, 2015 and 2014, the Company recognized $696, $835 and $520 of rental expense related to office space. As of December 31, 2016, future minimum lease payments under noncancelable office leases are as follows: 2017 $ 839 2018 489 $ 1,328 Restricted Cash and Letters of Credit The Company held a money market account of $200 to collateralize a credit card account with its bank, which was classified as restricted cash on the balance sheet as of December 31, 2016 and 2015. The Company is required to maintain a letter of credit totaling $70 for the benefit of the Landlord of the New Lease. The Landlord can draw against the letter of credit in the event of default by the Company. The Company held $70 in a money market account to collateralize the letter of credit, which amount was also included in restricted cash on the balance sheet as of December 31, 2016 and 2015. Intellectual Property Licenses The Company has a master license agreement with the University of Maryland, Baltimore (“UMB”). Pursuant to the license agreement, UMB granted an exclusive, worldwide license, with the right to sublicense, under certain patents and patent applications to make, have made, use, sell, offer to sell and import certain anti-androgen steroids, including galeterone, for the prevention, diagnosis, treatment or control of any human or animal disease. In addition, UMB granted the Company a first option to receive an exclusive license to UMB’s rights in certain improvements to the licensed products. The Company has exercised its option and acquired exclusive rights to licensed improvements under four amendments to the license agreement. The Company is obligated to pay UMB an annual maintenance fee of $10 each year until the first commercial sale of a product developed using the licensed technology. The Company is also obligated to make milestone payments of an additional $50 for the filing of each additional investigational new drug application filed for a licensed product, aggregate milestone payments of up to $150 associated with the development of a licensed product for a particular non-prostate The Company must also pay UMB a low-single product-by-licensed country-by-country last-to-expire non-royalty In January 2015, the Company entered into an exclusive license agreement with The Johns Hopkins University (“Johns Hopkins”) pursuant to which Johns Hopkins granted the Company an exclusive, worldwide license under certain patents and patent applications, and a non-exclusive know-how, In consideration for the rights granted to the Company under the license agreement, the Company made an upfront payment to Johns Hopkins of $75 following the execution of the license agreement, which was recognized as research and development expense during the year ended December 31, 2015. The Company is obligated to pay Johns Hopkins an annual minimum royalty of up to $30 and to make milestone payments to Johns Hopkins upon the achievement of specified technical and commercial milestones. If all such milestones were achieved, the total milestone payments owed to Johns Hopkins would equal $700 in the aggregate. During the year ended December 31, 2015, the Company expensed $50 upon the achievement of two of these milestones. The Company has not achieved any other milestones and, therefore, no additional liabilities for such milestone payments have been recorded in the Company’s financial statements. The Company must also pay Johns Hopkins single digit percentage royalties on aggregate worldwide net sales of licensed products (but not galeterone), including sales by sublicensees, on a licensed product-by-licensed country-by-country last-to-expire non-royalty Companion Diagnostic Development Agreement In March 2015, the Company entered into a project work plan with Qiagen Manchester Limited (“Qiagen”) under a Master Collaboration Agreement, dated January 12, 2015, between the Company and Qiagen (together with the project work plan, the “CDx Agreement”). Pursuant to the CDx Agreement, Qiagen had agreed to develop and commercialize a companion diagnostic test for use with galeterone to identify mCRPC patients with the AR-V7 AR-V7, Subject to the terms of the CDx Agreement, the Company paid Qiagen a fee for the exclusive right to have the circulating tumor cell enrichment technology used in the development of the companion diagnostic test, which was recognized as research and development expense during the year ended December 31, 2015. The Company also paid Qiagen fees for the development of the AR-V7 Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with each of its directors and executive officers, which provide, among other things, that the Company will indemnify such directors and executive officers to the fullest extent permitted by law for claims arising in his or her capacity as a director or officer. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred material costs as a result of the indemnification agreements described above. In addition, the Company maintains directors and officers insurance coverage. The Company is unable to predict if any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows and has not accrued any material liabilities related to such possible obligations in its financial statements as of December 31, 2016. Legal Proceedings On August 1, 2016, a purported stockholder of the Company filed a putative class action lawsuit in the U.S. District Court for the Southern District of New York against the Company, Jodie P. Morrison, and Lee H. Kalowski, entitled Doshi v. Tokai Pharmaceuticals, Inc., et al., No. 1:16-cv-06106 10b-5 On August 19, 2016, a purported stockholder of the Company filed a putative class action lawsuit in the Superior Court of the State of California, County of San Francisco, against the Company, Jodie P. Morrison, Lee H. Kalowski, Seth L. Harrison, Timothy J. Barberich, David A. Kessler, Joseph A. Yanchik, III, and the underwriters of the Company’s “IPO”, entitled Jackie888, Inc. v. Tokai Pharmaceuticals, Inc., et al., No. CGC-16-553796. On September 29, 2016, two purported stockholders of the Company filed a putative class action lawsuit in the U.S. District Court for the District of Massachusetts against the Company, Jodie Pope Morrison, Lee H. Kalowski, Seth L. Harrison, Timothy J. Barberich, David A. Kessler, Joseph A. Yanchik, III, and the underwriters of the Company’s IPO, entitled Garbowski, et al. v. Tokai Pharmaceuticals, Inc., et al., No. 1:16-cv-11963 10b-5. On December 5, 2016, a putative securities class action was filed in the Business Litigation Session of the Superior Court Department of the Suffolk County Trial Court, Massachusetts (“Massachusetts State Court”) against the Company, Jodie P. Morrison, Lee H. Kalowski, Seth L. Harrison, Timothy J. Barberich, David A. Kessler, Joseph A. Yanchik, III, and the underwriters of the Company’s IPO, entitled Wu v. Tokai Pharmaceuticals, Inc., et al., 16-3725 16-cv-12550, The Company believes it has valid defenses, and intends to engage in a vigorous defense of the litigation. However, the Company is unable to predict the ultimate outcome of these actions, and, therefore cannot estimate possible losses or ranges of losses, if any, or the materiality thereof. An unexpected unfavorable resolution of these matters in any reporting period may have a material adverse effect on the Company’s results of operations and cash flows for that period.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes During the years ended December 31, 2016, 2015 and 2014, the Company recorded no income tax benefits for the net operating losses incurred in each year, due to its uncertainty of realizing a benefit from those items. A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2016 2015 2014 Federal statutory income tax rate (34.0 )% (34.0 )% (34.0 )% Federal research and development tax credit (0.6 ) (0.5 ) (0.9 ) State taxes, net of federal benefit (5.2 ) (5.3 ) (4.5 ) Stock-based compensation expense 1.3 0.4 1.1 Other — 0.1 0.2 Increase in deferred tax asset valuation allowance 38.5 39.3 38.1 Effective income tax rate 0.0 % 0.0 % 0.0 % Net deferred tax assets as of December 31, 2016 and 2015 consisted of the following: December 31, 2016 2015 Deferred tax assets: Capitalized research and development expenses $ 47,594 $ 37,765 Net operating loss carryforwards 14,252 10,224 Stock-based compensation 1,956 1,371 Research and development tax credit carryforwards 1,590 1,273 Accrued expenses 207 339 Other 44 56 Total gross deferred tax assets 65,643 51,028 Valuation allowance (65,643 ) (51,028 ) Net deferred tax assets $ — $ — Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2016, 2015 and 2014 related primarily to the increase in capitalized research and development expenses, net operating loss carryforwards and stock-based compensation and were as follows: Year Ended December 31, 2016 2015 2014 Valuation allowance as of beginning of year $ 51,028 $ 33,272 $ 24,402 Decreases recorded as benefit to income tax provision — — — Increases recorded to income tax provision 14,615 17,756 8,870 Valuation allowance as of end of year $ 65,643 $ 51,028 $ 33,272 As of December 31, 2016, the Company had net operating loss carryforwards for federal and state income tax purposes of $38,200 and $34,300, respectively, which begin to expire in 2024 and 2030, respectively. As of December 31, 2016, the federal and state net operating loss carryforwards include $1,400 of deductions for stock option compensation for which the associated tax benefit will be credited to additional paid-in tax-exempt The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management has considered the Company’s history of cumulative net losses incurred since inception and its lack of commercialization of any products since inception and has concluded that it is more likely than not that the Company will not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance has been established against the deferred tax assets as of December 31, 2016 and 2015. Management reevaluates the positive and negative evidence at each reporting period. The Company has not recorded any amounts for unrecognized tax benefits as of December 31, 2016 or 2015. The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. There are currently no pending income tax examinations. The Company’s tax years are still open under statute from 2013 to the present. Earlier years may be examined to the extent that tax credit or net operating loss carryforwards are used in future periods. The Company’s policy is to record interest and penalties related to income taxes as part of its income tax provision.

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2016
Postemployment Benefits [Abstract]
401(k) Plan	11. 401(k) Plan The Company has a 401(k) plan available for participating employees who meet certain eligibility requirements. Eligible employees may defer a portion of their salary as defined by the plan. Company contributions to the plan may be made at the discretion of the Board of Directors. Since January 1, 2016, the Company has made matching contributions for the plan year ending December 31, 2016 at a rate of 100% of each employee’s contribution up to a maximum matching contribution of 3% of the employee’s eligible plan compensation and at a rate of 50% of each employee’s contribution in excess of 3% up to a maximum of 5% of the employee’s eligible plan compensation. For the year ended December 31, 2016, the Company made matching contributions of $127.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Related Party Transactions	12. Related Party Transactions In September 21, 2016, the Company entered into a consulting agreement with Apple Tree Life Sciences, Inc. (“Apple Tree”) under which Apple Tree agreed to provide consulting, advisory and related services to and for the Company from time to time. There is no fee for these services except for reimbursement of out of pocket expenses. Affiliates of Apple Tree beneficially own approximately 35% of the Company, and Dr. Seth Harrison, a member of the Company’s board of directors, is a principal of Apple Tree. The Company had an outstanding loan to a former advisor comprised of unpaid principal and interest in the amount of $220 that was deemed uncollectable and as a result, was fully reserved for in 2007. In 2014, the Company started to receive repayment of this note. This loan was fully repaid in April 2015. The Company recorded $49 and $158 for the years ended December 31, 2015 and 2014, respectively, in interest and other income, net, representing cash collected during those periods.

Share Purchase Agreement

Share Purchase Agreement	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Share Purchase Agreement	13. Share Purchase Agreement On December 21, 2016, the Company entered into the Share Purchase Agreement with Otic and the Selling Shareholders pursuant to which, among other things, each Selling Shareholder agreed to sell to the Company, and the Company agreed to purchase from each Selling Shareholder, all of the Otic Shares owned by such Selling Shareholder. Immediately following the closing of the Otic Transaction, the Selling Shareholders are expected to own approximately 60% of the Company’s outstanding common stock (62% if all of Otic’s outstanding options and warrants are exercised prior to closing). Consummation of the Otic Transaction is subject to certain closing conditions, including, among other things, approval by the Company’s stockholders. The Share Purchase Agreement contains certain termination rights for both the Company and Otic, and further provides that, upon termination of the Share Purchase Agreement under specified circumstances, the Company may be required to pay Otic a termination fee of $1,000, or Otic may be required to pay the Company a termination fee of $1,500. Upon consummation of the Otic Transaction, the Company will owe its strategic advisor $1,000. There can be no assurances that the Otic Transaction will be consummated. The Company amended and restated the Share Purchase Agreement on March 2, 2017 to update the allocation of shares of the Company’s common stock among the Selling Shareholders and to extend to May 31, 2017, the date after which the Company or Otic may terminate the Share Purchase Agreement. In addition, the Company has entered into a commitment letter with Otic and certain purchasers set forth therein under which the purchasers have agreed to invest up to $7,000 of new capital in Otic and/or Tokai prior to or upon the closing of the Otic Transaction. Pursuant to this commitment letter, on January 31, 2017, the Company entered into a stock purchase agreement with the parties to the commitment letter under which such parties agreed to purchase 3,603,601 shares of the Company’s common stock at a price of $1.11 per share. The purchase and sale of the Company’s common stock pursuant to this stock purchase agreement will occur at the time of the closing of the Otic Transaction. The remaining $3,000 will be invested in Otic prior to the closing of the Otic Transaction through the exercise of outstanding warrants.

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)	14. Selected Quarterly Financial Data (Unaudited) Three Months Ended Dec. 31, (1) Sept. 30, (1) June 30, March 31, Dec. 31, Sept. 30, June 30, March 31, Statements of Operations Data: Revenue $ — $ — $ — $ — $ — $ — $ — $ — Loss from operations (3,760 ) (9,308 ) (13,575 ) (11,480 ) (11,072 ) (11,907 ) (8,982 ) (13,300 ) Net loss (3,737 ) (9,270 ) (13,526 ) (11,426 ) (11,017 ) (11,853 ) (8,957 ) (13,260 ) Basic and diluted net loss per share $ (0.17 ) $ (0.41 ) $ (0.60 ) $ (0.51 ) $ (0.49 ) $ (0.53 ) $ (0.40 ) $ (0.59 ) (1) In July 2016, the Company announced its plan to discontinue the ARMOR3-SV

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. Generally Accepted Accounting Principles (“GAAP”) requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting periods. Significant estimates, assumptions and judgments reflected in these financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.
Cash Equivalents	Cash Equivalents The Company considers all short-term, highly liquid investments with original maturities of ninety days or less at date of purchase to be cash equivalents. Cash equivalents, which consist of money market accounts, are stated at fair value.
Marketable Securities	Marketable Securities The Company’s marketable securities are classified as available-for-sale
Concentration of Risk	Concentration of Risk Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents and marketable securities. The Company has all cash and cash equivalents and marketable securities’ balances at two accredited financial institutions, in amounts that exceed federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company is dependent on third-party manufacturers to supply products for research and development activities in its programs. In particular, the Company relies and expects to continue to rely on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value under GAAP. 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. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices) such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation expense is recognized using the straight-line method based upon estimated useful lives as follows: Years Lab equipment 3 Computer equipment 3 Furniture and fixtures 5 Leasehold improvements Shorter of life of lease or estimated useful life Upon retirement or sale of property and equipment, the cost and related accumulated depreciation of such property and equipment disposed of are removed from the accounts and any resulting gain or loss is included in loss from operations.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends, and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows. During the year ended December 31, 2016, the Company recorded an impairment loss of $237 related to property and equipment, including lab equipment which will no longer be used as a result of the discontinuation of the ARMOR3-SV
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred. Included in research and development expenses are salaries, stock-based compensation and benefits of employees, third-party license fees and other operational costs related to the Company’s research and development activities, including manufacturing expenses and external costs of outside vendors engaged to conduct both preclinical studies and clinical trials. The Company expenses raw materials used to manufacture its drug substance when received. As part of the process of preparing financial statements, the Company is required to estimate its accrued research and development expenses. This process involves reviewing open contracts and purchase orders, communicating with company personnel and outside vendors to identify services that have been performed on the Company’s behalf and estimating the level of service performed and the associated costs incurred for the services when the Company has not yet been invoiced or otherwise notified of the actual costs. The majority of the Company’s service providers invoice in arrears for services performed, on a pre-determined • clinical research organizations in connection with clinical trials; • investigative sites or other providers in connection with clinical trials; • Qiagen in connection with the development of the AR-V7 • vendors in connection with preclinical development activities; and • vendors related to product manufacturing, development and distribution of clinical supplies. The Company bases its expenses related to clinical trials on its estimates of the services received and efforts expended pursuant to contracts with multiple clinical research organizations and investigative sites that manage and conduct clinical trials on the Company’s 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 vendors will exceed the level of services provided and result in a prepayment of the clinical expense. Payments under some of these contracts depend on factors such as the successful enrollment of patients 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 patients, 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 its estimate, the Company adjusts the accrual or amount of prepaid expense accordingly. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low in any particular period. For the years ended December 31, 2016, 2015 and 2014, the Company has not made any material adjustments to its prior estimates of accrued research and development expenses.
Patent Costs	Patent Costs All patent-related costs incurred in connection with filing and prosecuting patent applications are recorded as general and administrative expenses as incurred, as recoverability of such expenditures is uncertain.
Accounting for Stock-Based Compensation	Accounting for Stock-Based Compensation The Company measures all stock options and other stock-based awards granted to employees and directors at the fair value on the date of the grant using the Black-Scholes option-pricing model. The fair value of the awards is recognized as expense, net of estimated forfeitures, over the requisite service period, which is generally the vesting period of the respective award. The straight-line method of expense recognition is applied to all awards with service-only conditions, while the graded vesting method is applied to all grants with both service and performance conditions. For stock-based awards granted to non-employees, non-employees re-measured The Company classifies stock-based compensation expense in its statement of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. The Company recognizes compensation expense for only the portion of awards that are expected to vest. In developing a forfeiture rate estimate, the Company has considered its historical experience to estimate pre-vesting
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been recognized in the financial statements or in the Company’s tax returns. Deferred taxes are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. The Company accounts for uncertainty in income taxes recognized in its financial statements by applying a two-step
Segment Data	Segment Data The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company’s singular focus is on developing novel proprietary therapies for the treatment of prostate cancer and other hormonally-driven diseases. No revenue has been generated since inception. All of the Company’s assets are located in the United States.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the years ended December 31, 2016 and 2015, the Company’s only element of other comprehensive loss was unrealized gains (losses) on marketable securities. For the year ended December 31, 2014, there was no difference between net loss and comprehensive loss.
Net Income (Loss) Per Share	Net Income (Loss) Per Share Basic net income (loss) per share is computed by dividing the net income (loss) the weighted average number of common shares outstanding for the period. Diluted net income (loss) per share is computed by dividing the diluted net income (loss) by the weighted average number of common shares, including potential dilutive common shares assuming the dilutive effect of outstanding stock options and unvested restricted common shares, as determined using the treasury stock method. For periods in which the Company has reported net losses, diluted net loss per common share is the same as basic net loss per common share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The following common stock equivalents outstanding as of December 31, 2016, 2015 and 2014 were excluded from the computation of diluted net loss per share for the years ended December 31, 2016, 2015 and 2014, because they had an anti-dilutive impact: December 31, 2016 2015 2014 Stock options to purchase common stock 1,896,169 2,861,011 2,146,927 Unvested restricted common stock units — 40,953 54,604 1,896,169 2,901,964 2,201,531
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases 2016-02”), 2016-02 In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation 2016-09”). 2016-09 2016-09 In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows: Restricted Cash 2016-18”). 2016-18 2016-18

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Schedule of Property and Equipment	Depreciation expense is recognized using the straight-line method based upon estimated useful lives as follows: Years Lab equipment 3 Computer equipment 3 Furniture and fixtures 5 Leasehold improvements Shorter of life of lease or estimated useful life
Schedule of Common Stock Equivalents, Excluded from Computation of Diluted Net Loss per Share	The following common stock equivalents outstanding as of December 31, 2016, 2015 and 2014 were excluded from the computation of diluted net loss per share for the years ended December 31, 2016, 2015 and 2014, because they had an anti-dilutive impact: December 31, 2016 2015 2014 Stock options to purchase common stock 1,896,169 2,861,011 2,146,927 Unvested restricted common stock units — 40,953 54,604 1,896,169 2,901,964 2,201,531

Marketable Securities and Fai23

Marketable Securities and Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Schedule of Marketable Securities by Security Type	As of December 31, 2016, marketable securities by security type consisted of: Amortized Gross Gross Estimated Certificates of Deposit (due within one year) $ 1,175 $ — $ — $ 1,175 United States Treasury Notes (due within one year) 3,001 — (1 ) 3,000 Total $ 4,176 $ — $ (1 ) $ 4,175 As of December 31, 2015, marketable securities by security type consisted of: Amortized Gross Gross Estimated Certificates of Deposit (due within one year) $ 13,709 $ — $ — $ 13,709 Certificates of Deposit (due after one year through two years) 1,178 — — 1,178 United States Treasury Notes (due within one year) 22,596 — (47 ) 22,549 United States Treasury Notes (due after one year through two years) 2,506 — (8 ) 2,498 Total $ 39,989 $ — $ (55 ) $ 39,934
Schedule of Fair Value Measured on Recurring Basis	The following tables present the Company’s fair value hierarchy for its cash equivalents and marketable securities, which are measured at fair value on a recurring basis as of December 31, 2016 and 2015: Fair Value Measurements at December 31, 2016 Using Level 1 Level 2 Level 3 Total Cash equivalents: Money Market Instruments $ — $ 17,748 $ — $ 17,748 Marketable securities: Certificates of Deposit — 1,175 — 1,175 United States Treasury Notes — 3,000 — 3,000 Total $ — $ 21,923 $ — $ 21,923 Fair Value Measurements at December 31, 2015 Level 1 Level 2 Level 3 Total Cash equivalents: Money Market Instruments $ — $ 18,361 $ — $ 18,361 Marketable securities: Certificates of Deposit — 14,887 — 14,887 United States Treasury Notes — 25,047 — 25,047 Total $ — $ 58,295 $ — $ 58,295

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment, net consisted of the following as of December 31, 2016 and 2015: December 31, 2016 2015 Computer equipment $ 162 $ 243 Leasehold improvements 66 66 Lab equipment — 322 Furniture and fixtures — 23 228 654 Less: Accumulated depreciation (130 ) (165 ) $ 98 $ 489

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2016
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following as of December 31, 2016 and 2015: December 31, 2016 2015 Accrued research and development expenses $ 907 $ 3,188 Accrued professional fees 871 699 Accrued payroll and related expenses 394 900 Accrued other 217 167 $ 2,389 $ 4,954

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Fair Value of Stock Options Granted	The following table sets forth the assumptions that the Company used to determine the fair value of the stock options granted, presented on a weighted average basis: Year Ended December 31, 2016 2015 2014 Risk-free interest rate 1.52 % 1.79 % 1.83 % Expected term (in years) 5.91 6.01 5.95 Expected volatility 74.7 % 74.2 % 79.4 % Expected dividend yield 0 % 0 % 0 %
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity from January 1, 2016 through December 31, 2016: Shares Issuable Weighted Weighted Aggregate (In years) Outstanding as of December 31, 2015 2,861,011 $ 7.57 8.3 $ 7,906 Granted 324,900 6.17 Exercised (30,856 ) 1.18 Forfeited (1,258,886 ) 8.90 Outstanding as of December 31, 2016 1,896,169 $ 6.55 6.1 $ 13 Options vested and expected to vest as of December 31, 2016 1,889,406 $ 6.53 6.1 $ 13 Options exercisable as of December 31, 2016 1,434,904 $ 5.58 5.4 $ 13
Summary of Restricted Stock Unit Activity	The table below summarizes the Company’s restricted stock unit activity from January 1, 2016 through December 31, 2016: Shares Weighted Unvested restricted common stock units as of December 31, 2015 40,953 $ 15.00 Issued — — Vested (13,651 ) 15.00 Forfeited (27,302 ) 15.00 Unvested restricted common stock units as of December 31, 2016 —
Schedule of Stock-Based Compensation Expense Related to Stock Options and Restricted Common Stock Units	The Company recorded stock-based compensation expense related to stock options and restricted common stock units in the following expense categories of its statements of operations: Year Ended December 31, 2016 2015 2014 Research and development $ 526 $ 634 $ 552 General and administrative 2,476 2,267 1,556 $ 3,002 $ 2,901 $ 2,108

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments Under Noncancelable Office Leases	As of December 31, 2016, future minimum lease payments under noncancelable office leases are as follows: 2017 $ 839 2018 489 $ 1,328

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Reconciliation of U.S. Federal Statutory Income Tax Rate	A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2016 2015 2014 Federal statutory income tax rate (34.0 )% (34.0 )% (34.0 )% Federal research and development tax credit (0.6 ) (0.5 ) (0.9 ) State taxes, net of federal benefit (5.2 ) (5.3 ) (4.5 ) Stock-based compensation expense 1.3 0.4 1.1 Other — 0.1 0.2 Increase in deferred tax asset valuation allowance 38.5 39.3 38.1 Effective income tax rate 0.0 % 0.0 % 0.0 %
Schedule of Net Deferred Tax Assets	Net deferred tax assets as of December 31, 2016 and 2015 consisted of the following: December 31, 2016 2015 Deferred tax assets: Capitalized research and development expenses $ 47,594 $ 37,765 Net operating loss carryforwards 14,252 10,224 Stock-based compensation 1,956 1,371 Research and development tax credit carryforwards 1,590 1,273 Accrued expenses 207 339 Other 44 56 Total gross deferred tax assets 65,643 51,028 Valuation allowance (65,643 ) (51,028 ) Net deferred tax assets $ — $ —
Summary of Changes in Valuation Allowance for Deferred Tax Assets	Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2016, 2015 and 2014 related primarily to the increase in capitalized research and development expenses, net operating loss carryforwards and stock-based compensation and were as follows: Year Ended December 31, 2016 2015 2014 Valuation allowance as of beginning of year $ 51,028 $ 33,272 $ 24,402 Decreases recorded as benefit to income tax provision — — — Increases recorded to income tax provision 14,615 17,756 8,870 Valuation allowance as of end of year $ 65,643 $ 51,028 $ 33,272

Selected Quarterly Financial 29

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Quarterly Financial Data	Dec. 31, (1) Sept. 30, (1) June 30, March 31, Dec. 31, Sept. 30, June 30, March 31, Statements of Operations Data: Revenue $ — $ — $ — $ — $ — $ — $ — $ — Loss from operations (3,760 ) (9,308 ) (13,575 ) (11,480 ) (11,072 ) (11,907 ) (8,982 ) (13,300 ) Net loss (3,737 ) (9,270 ) (13,526 ) (11,426 ) (11,017 ) (11,853 ) (8,957 ) (13,260 ) Basic and diluted net loss per share $ (0.17 ) $ (0.41 ) $ (0.60 ) $ (0.51 ) $ (0.49 ) $ (0.53 ) $ (0.40 ) $ (0.59 ) (1) In July 2016, the Company announced its plan to discontinue the ARMOR3-SV

Nature of the Business and Ba30

Nature of the Business and Basis of Presentation - Additional Information (Detail) $ in Thousands	Jan. 31, 2017Patient	Jul. 31, 2016	Mar. 31, 2017USD ($)	Sep. 30, 2016	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Nature Of Business And Basis Of Presentation [Line Items]
Percentage of reduction in workforce		60.00%		60.00%
Payments for Severance					$ 1,042
Accrued expenses					2,389	$ 4,954
Accumulated deficit					(169,397)	$ (131,438)
Cash and investments					27,398
Subsequent Event [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Number of patients | Patient	10
Employee Severance [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Payments for Severance					842
Accrued expenses					200
Employee Severance [Member] | Scenario, Forecast [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Payments for Severance			$ 200
Research and Development [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Payments for Severance					369
General and Administrative [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Payments for Severance					$ 673

Summary of Significant Accoun31

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)
Accounting Policies [Abstract]
Cash equivalents, maturity period	Ninety days or less
Impairment of property and equipment	$ 237,000
Income tax examination, likelihood of settlement, description	The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement.
Income tax examination, likelihood of settlement, percentage	50.00%
Revenue since inception	$ 0

Summary of Significant Accoun32

Summary of Significant Accounting Policies - Schedule of Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2016
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	3 years
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	3 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful life	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, estimated useful lives	Shorter of life of lease or estimated useful life

Summary of Significant Accoun33

Summary of Significant Accounting Policies - Schedule of Common Stock Equivalents, Excluded from Computation of Diluted Net Loss 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]
Total options, restricted stock units exercisable or convertible into common stock	1,896,169	2,901,964	2,201,531
Stock Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total options, restricted stock units exercisable or convertible into common stock	1,896,169	2,861,011	2,146,927
Unvested Restricted Common Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total options, restricted stock units exercisable or convertible into common stock		40,953	54,604

Marketable Securities and Fai34

Marketable Securities and Fair Value Measurements - Schedule of Marketable Securities by Security Type (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 4,176	$ 39,989
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(55)
Estimated Fair Value	4,175	39,934
Certificates of Deposit Due within One Year [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,175	13,709
Gross Unrealized Gains	0	0
Estimated Fair Value	1,175	13,709
Certificates of Deposit Due after One Year through Two Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		1,178
Gross Unrealized Gains		0
Estimated Fair Value		1,178
United States Treasury Notes Due Within One Year [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,001	22,596
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(47)
Estimated Fair Value	$ 3,000	22,549
United States Treasury Notes Due after One Year through Two Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,506
Gross Unrealized Gains		0
Gross Unrealized Losses		(8)
Estimated Fair Value		$ 2,498

Marketable Securities and Fai35

Marketable Securities and Fair Value Measurements - Schedule of Fair Value Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, cash equivalents and marketable securities	$ 21,923	$ 58,295
Money Market Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, cash equivalents and marketable securities	17,748	18,361
Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, cash equivalents and marketable securities	1,175	14,887
United States Treasury Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, cash equivalents and marketable securities	3,000	25,047
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, cash equivalents and marketable securities	21,923	58,295
Level 2 [Member] | Money Market Instruments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, cash equivalents and marketable securities	17,748	18,361
Level 2 [Member] | Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, cash equivalents and marketable securities	1,175	14,887
Level 2 [Member] | United States Treasury Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, cash equivalents and marketable securities	$ 3,000	$ 25,047

Property and Equipment, net - S

Property and Equipment, net - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 228	$ 654
Less: Accumulated depreciation	(130)	(165)
Property and Equipment, net	98	489
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	162	243
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross	$ 66	66
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross		322
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, gross		$ 23

Property and Equipment, net - A

Property and Equipment, net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 171	$ 109	$ 21

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 907	$ 3,188
Accrued professional fees	871	699
Accrued payroll and related expenses	394	900
Accrued other	217	167
Total	$ 2,389	$ 4,954

Redeemable Convertible Prefer39

Redeemable Convertible Preferred Stock - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Preferred stock, shares outstanding	0	0
Conversion of Redeemable Preferred Stock	10.47-for-1 basis
Series A, B-1, B-2, C,D-1, D-2, D-3 and E Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding	0	0

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Oct. 09, 2014	Sep. 22, 2014	Dec. 31, 2016	Dec. 31, 2014
Class of Stock [Line Items]
Reverse stock split conversion description			The Company effected a 1-for-10.47 reverse stock split of its issued and outstanding shares of common stock.
Proceeds from initial public offering, net of underwriting discounts and commissions				$ 97,929
Number of common shares issued on conversion of redeemable convertible preferred stock		14,860,173
Option to Purchase Additional Shares of Common Stock Granted to the Underwriters in Connection with the IPO [Member]
Class of Stock [Line Items]
Common Stock, shares issued and sold	540,000
Common stock, public offering price per share	$ 15
Proceeds from initial public offering, net of underwriting discounts and commissions	$ 7,533
Common Stock [Member]
Class of Stock [Line Items]
Number of common shares issued on conversion of redeemable convertible preferred stock				14,860,173
Common Stock [Member] | IPO [Member]
Class of Stock [Line Items]
Common Stock, shares issued and sold		6,480,000		7,020,000
Common stock, public offering price per share		$ 15
Proceeds from initial public offering, net of underwriting discounts and commissions		$ 87,062

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jan. 01, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 01, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted to employee		324,900	996,845	1,039,155
Market value of common stock		$ 0.98	$ 8.72
Weighted average grant date fair value of stock options granted		$ 4.02	$ 6.94	$ 6.70
Total intrinsic value of stock options exercised		$ 144	$ 2,236	$ 35
Unrecognized stock-based compensation expense		$ 2,675
Weighted average period of unrecognized stock-based compensation expense expects to be recognize		2 years 2 months 12 days
Stock-based compensation expense		$ 3,002	$ 2,901	$ 2,108
Unvested Restricted Common Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted		0	0	54,604
Restricted stock units granted, fair value		$ 0		$ 15
Performance-based Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				$ 880
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock options		3 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock options		4 years
Maximum [Member] | Unvested Restricted Common Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of stock options				4 years
2014 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized for issuance		1,745,413
Maximum annual increase in common stock reserved for future issuance	1,800,000
Additional shares of common stock, percentage	4.00%
Remaining shares available for issuance		3,021,327
2014 Stock Incentive Plan [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increased number of shares reserved for issuance					905,666
2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized for issuance		225,000
Maximum annual increase in common stock reserved for future issuance		450,000
Additional shares of common stock, percentage		1.00%
2014 Employee Stock Purchase Plan [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increased number of shares reserved for issuance					226,416

Stock-Based Awards - Fair Value

Stock-Based Awards - Fair Value of Stock Options Granted (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Risk-free interest rate	1.52%	1.79%	1.83%
Expected term (in years)	5 years 10 months 28 days	6 years 4 days	5 years 11 months 12 days
Expected volatility	74.70%	74.20%	79.40%
Expected dividend yield	0.00%	0.00%	0.00%

Stock-Based Awards - Summary of

Stock-Based Awards - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Shares Issuable Under Options
Outstanding as of December 31, 2015	2,861,011
Granted	324,900	996,845	1,039,155
Exercised	(30,856)
Forfeited	(1,258,886)
Outstanding as of December 31, 2016	1,896,169	2,861,011
Options vested and expected to vest as of December 31, 2016	1,889,406
Options exercisable as of December 31, 2016	1,434,904
Weighted Average Exercise Price
Outstanding as of December 31, 2015	$ 7.57
Granted	6.17
Exercised	1.18
Forfeited	8.90
Outstanding as of December 31, 2016	6.55	$ 7.57
Options vested and expected to vest as of December 31, 2016	6.53
Options exercisable as of December 31, 2016	$ 5.58
Weighted Average Remaining Contractual Term (In years)
Outstanding as of December 31, 2015	6 years 1 month 6 days	8 years 3 months 18 days
Options vested and expected to vest as of December 31, 2016	6 years 1 month 6 days
Options exercisable as of December 31, 2016	5 years 4 months 24 days
Aggregate Intrinsic Value
Aggregate intrinsic value, Outstanding	$ 13	$ 7,906
Options vested and expected to vest as of December 31, 2016	13
Options exercisable as of December 31, 2016	$ 13

Stock-Based Awards - Summary 44

Stock-Based Awards - Summary of Restricted Stock Unit Activity (Detail) - Unvested Restricted Common Stock Units [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Shares
Unvested restricted common stock units as of December 31, 2015	40,953
Issued	0	0	54,604
Vested	(13,651)
Forfeited	(27,302)
Unvested restricted common stock units as of December 31, 2016		40,953
Weighted Average Grant Date Fair Value
Unvested restricted common stock units as of December 31, 2015	$ 15
Issued	0		$ 15
Vested	15
Forfeited	$ 15
Unvested restricted common stock units as of December 31, 2016		$ 15

Stock-Based Awards - Schedule o

Stock-Based Awards - Schedule of Stock-Based Compensation Expense Related to Stock Options and Restricted Common Stock Units (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 expense	$ 3,002	$ 2,901	$ 2,108
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	526	634	552
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,476	$ 2,267	$ 1,556

Commitments and Contingencies46

Commitments and Contingencies (Leases) - Additional Information (Detail) $ in Thousands	1 Months Ended		12 Months Ended
	Jun. 30, 2015	Feb. 28, 2015ft²	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Other Commitments [Line Items]
Rental expense			$ 696	$ 835	$ 520
Sublease [Member]
Other Commitments [Line Items]
Area of office space | ft²		15,981
Leases expiration date			Dec. 31, 2016
New Lease [Member]
Other Commitments [Line Items]
Leases expiration date	Jul. 31, 2018
Cambridge Lease [Member]
Other Commitments [Line Items]
Exit cost				$ 133
Operating service agreement period				30 days

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Noncancelable Office Leases (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,017	$ 839
2,018	489
Total	$ 1,328

Commitments and Contingencies48

Commitments and Contingencies (Restricted Cash and Letters of Credit) - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Other Commitments [Line Items]
Restricted cash	$ 120	$ 270
Money Market Instruments [Member]
Other Commitments [Line Items]
Restricted cash	200	200
Money Market Instruments [Member] | Letter of Credit [Member]
Other Commitments [Line Items]
Restricted cash	$ 70	$ 70

Commitments and Contingencies49

Commitments and Contingencies (Intellectual Property Licenses) - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2016USD ($)AmendmentsMilestone	Dec. 31, 2015USD ($)Milestone	Dec. 31, 2014Milestone
Other Commitments [Line Items]
Number of milestones achieved | Milestone		0	0	0
License Agreement [Member] | Johns Hopkins [Member]
Other Commitments [Line Items]
Percentage of non-royalty sub license income	20.00%
Upfront payment			$ 75,000
Potential milestone payments under license agreement			700,000
Milestone payments expensed during period			50,000
Additional liabilities for milestone payments			0
License Agreement [Member] | Johns Hopkins [Member] | Minimum [Member]
Other Commitments [Line Items]
Annual royalty			$ 30,000
Master License Agreement [Member] | UMB [Member]
Other Commitments [Line Items]
Number of amendments | Amendments		4
Annual maintenance fee		$ 10,000
Percentage of non-royalty sub license income		10.00%
Master License Agreement [Member] | UMB [Member] | Minimum [Member]
Other Commitments [Line Items]
Annual royalty		$ 50,000
IND [Member] | Master License Agreement [Member] | UMB [Member] | Upon Filing IND Application For Licensed Product [Member]
Other Commitments [Line Items]
Milestone payment		50,000
IND [Member] | Master License Agreement [Member] | UMB [Member] | Upon FDA Approval [Member]
Other Commitments [Line Items]
Milestone payment		100,000
Investigational Drug Application Non Prostate Disease [Member] | Master License Agreement [Member] | UMB [Member] | Maximum [Member]
Other Commitments [Line Items]
Aggregate milestone payments associated with development of licensed product		$ 150,000

Commitments and Contingencies50

Commitments and Contingencies (Commercial Development Agreement) - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Commitments [Line Items]
Research and development expense	$ 25,024	$ 32,638	$ 14,577
Law suit filing date	February 27, 2017
Master Collaboration Agreement [Member] | Qiagen [Member]
Other Commitments [Line Items]
Final payment	$ 1,099
Research and development expense	$ 1,099

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Tax Credit Carryforward [Line Items]
Income tax benefits	$ 0	$ 0	$ 0
Income tax benefits related to the deduction of share-based compensation	1,400,000
Research and development tax credit carryforwards for federal and state income tax purposes	1,590,000	1,273,000
Unrecognized tax benefits	0	$ 0
Domestic Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards for federal income tax purposes	$ 38,200,000
Net operating loss carryforwards for federal and state income tax, expiration period	2,024
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Research and development tax credit carryforwards for federal and state income tax purposes	$ 1,279,000
Research and development tax credit carryforwards for federal and state income tax purposes, expiration period	2,025
State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards for State income tax purposes	$ 34,300,000
Net operating loss carryforwards for federal and state income tax, expiration period	2,030
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward [Line Items]
Research and development tax credit carryforwards for federal and state income tax purposes	$ 471,000
Research and development tax credit carryforwards for federal and state income tax purposes, expiration period	2,028

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of U.S. Federal Statutory Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	(34.00%)	(34.00%)	(34.00%)
Federal research and development tax credit	(0.60%)	(0.50%)	(0.90%)
State taxes, net of federal benefit	(5.20%)	(5.30%)	(4.50%)
Stock-based compensation expense	1.30%	0.40%	1.10%
Other		0.10%	0.20%
Increase in deferred tax asset valuation allowance	38.50%	39.30%	38.10%
Effective income tax rate	0.00%	0.00%	0.00%

Income Taxes - Schedule of Net

Income Taxes - Schedule of Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Capitalized research and development expenses	$ 47,594	$ 37,765
Net operating loss carryforwards	14,252	10,224
Stock-based compensation	1,956	1,371
Research and development tax credit carryforwards	1,590	1,273
Accrued expenses	207	339
Other	44	56
Total gross deferred tax assets	65,643	51,028
Valuation allowance	(65,643)	(51,028)	$ (33,272)	$ (24,402)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Summary of Chang

Income Taxes - Summary of Changes in Valuation Allowance for Deferred Tax Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Valuation allowance, beginning balance	$ 51,028	$ 33,272	$ 24,402
Decreases recorded as benefit to income tax provision	0	0	0
Increases recorded to income tax provision	14,615	17,756	8,870
Valuation allowance, ending balance	$ 65,643	$ 51,028	$ 33,272

401(k) Plan - Additional Inform

401(k) Plan - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Defined Contribution Plan Disclosure [Line Items]
Company contributions to 401 (k) plan	$ 127
100% Matching Employer Contribution [Member] | Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Employee's contribution	3.00%
Employer's contribution	100.00%
50% Matching Employer Contribution [Member] | Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Employee's contribution	5.00%
Employer's contribution	50.00%
50% Matching Employer Contribution [Member] | Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Employee's contribution	3.00%

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 21, 2016	Dec. 31, 2007
Apple Tree Life Sciences, Inc. [Member] | Consulting Agreement [Member]
Related Party Transaction [Line Items]
Beneficial ownership percentage				35.00%
Former Advisor [Member]
Related Party Transaction [Line Items]
Balance due, fully reserved for					$ 220
Payments from loans receivable		$ 49	$ 158
Loan repayment date	2015-04

Share Purchase Agreement - Addi

Share Purchase Agreement - Additional Information (Detail) - USD ($)	Dec. 21, 2016	Jan. 31, 2017
Share Purchase Agreement [Line Items]
Strategic advisor fees payable	$ 1,000,000
Termination fee payable under share purchase agreement	$ 1,000,000
Otic Pharma, Ltd. [Member]
Share Purchase Agreement [Line Items]
Percentage of ownership if Options and warrants are exercised before closing	62.00%
Percentage of ownership	60.00%
Termination fee receivable under share purchase agreement	$ 1,500,000
Otic Pharma, Ltd. [Member] | Subsequent Event [Member]
Share Purchase Agreement [Line Items]
Number of shares Issued under Stock purchase agreement		3,603,601
Price of shares Issued under Stock purchase agreement		$ 1.11
Investment through exercise of warrants		3,000,000
Otic Pharma, Ltd. [Member] | Subsequent Event [Member] | Maximum [Member]
Share Purchase Agreement [Line Items]
Investment		$ 7,000,000

Selected Quarterly Financial 58

Selected Quarterly Financial Data (Unaudited) - Schedule of Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended										12 Months Ended
	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	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]
Revenue	$ 0		$ 0		$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Loss from operations	(3,760)		(9,308)		(13,575)	(11,480)	(11,072)	(11,907)	(8,982)	(13,300)	(38,123)	(45,261)	(23,462)
Net loss	$ (3,737)		$ (9,270)		$ (13,526)	$ (11,426)	$ (11,017)	$ (11,853)	$ (8,957)	$ (13,260)	$ (37,959)	$ (45,087)	$ (23,296)
Basic and diluted net loss per share	$ (0.17)		$ (0.41)		$ (0.60)	$ (0.51)	$ (0.49)	$ (0.53)	$ (0.40)	$ (0.59)	$ (1.68)	$ (2.01)	$ (3.60)
[1]	In July 2016, the Company announced its plan to discontinue the ARMOR3-SV Phase 3 clinical trial and reduced its workforce by approximately 60%.

Selected Quarterly Financial 59

Selected Quarterly Financial Data (Unaudited) - Schedule of Selected Quarterly Financial Data (Parenthetical) (Detail)	1 Months Ended	3 Months Ended
	Jul. 31, 2016	Sep. 30, 2016
Quarterly Financial Information Disclosure [Abstract]
Percentage of reduction in workforce	60.00%	60.00%