Trevena (TRVN) 10-K 9 Mar 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Mar. 03, 2016	Jun. 30, 2015
Document and Entity Information
Entity Registrant Name	TREVENA INC
Entity Central Index Key	1,429,560
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Smaller Reporting Company
Entity Public Float			$ 144.6
Entity Common Stock, Shares Outstanding		52,169,958
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY

Balance Sheets

Balance Sheets - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 46,773,566	$ 36,205,559
Marketable securities	125,864,447	70,698,640
Prepaid expenses and other current assets	1,892,217	669,155
Total current assets	174,530,230	107,573,354
Property and equipment, net	696,280	553,294
Restricted cash	112,620	112,410
Intangible asset, net	14,844
Total assets	175,353,974	108,239,058
Current liabilities:
Accounts payable	6,749,625	4,342,480
Accrued expenses and other current liabilities	3,029,782	2,578,269
Deferred revenue	3,750,000
Deferred rent	43,907	38,359
Total current liabilities	13,573,314	6,959,108
Loans payable, net	18,185,898	1,692,884
Capital lease, net of current portion	7,942	10,677
Deferred rent, net of current portion	238,917	281,885
Warrant liability	153,238	82,851
Other long term liabilities	63,200	8,025
Total liabilities	$ 32,222,509	$ 9,035,430
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock - $0.001 par value; 100,000 shares authorized, 50,802,603 and 39,241,173 shares issued and outstanding at December 31, 2015 and 2014, respectively	$ 50,802	$ 39,241
Preferred stock - $0.001 par value; 5,000,000 shares authorized, none issued
Additional paid-in capital	$ 325,784,484	$ 231,152,894
Accumulated deficit	(182,497,965)	(131,969,725)
Accumulated other comprehensive income (loss)	(205,856)	(18,782)
Total stockholders' equity	143,131,465	99,203,628
Total liabilities, redeemable convertible preferred stock and stockholders' equity	$ 175,353,974	$ 108,239,058

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	50,802,603	39,241,173
Common stock, shares outstanding	50,802,603	39,241,173
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Collaboration revenue	$ 6,250,000
Total revenue	6,250,000
Operating expenses:
General and administrative	12,797,010	$ 9,403,254
Research and development	44,074,157	40,546,666
Total operating expenses	56,871,167	49,949,920
Loss from operations	(50,621,167)	(49,949,920)
Other income (expense):
Change in fair value of warrant liability	(70,387)	122,412
Miscellaneous income	174,338	184,015
Loss on asset disposal	(7,864)	(4,104)
Interest income	331,205	17,372
Interest expense	(334,365)	(70,650)
Total other income	92,927	249,045
Net loss	(50,528,240)	(49,700,875)
Accretion of redeemable convertible preferred stock		(28,521)
Net loss attributable to common stockholders	(50,528,240)	(49,729,396)
Other comprehensive income, net:
Change in unrealized loss on marketable securities	(187,074)	(18,782)
Other comprehensive gains	(187,074)	(18,782)
Comprehensive loss	$ (50,715,314)	$ (49,748,178)
Per share information:
Net loss per share of common stock, basic and diluted (in dollars per share)	$ (1.15)	$ (2.02)
Weighted average shares outstanding, basic and diluted (in shares)	43,794,276	24,655,603

Statements of Redeemable Conver

Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity - USD ($)	Series A convertible preferred stock	Series B convertible preferred stock	Series B 1 convertible preferred stock	Series C convertible preferred stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Total
Balance at Dec. 31, 2013	$ 25,024,373	$ 30,778,700	$ 4,823,079	$ 59,935,986					$ 120,562,138
Balance (in shares) at Dec. 31, 2013	25,074,999	30,800,000	4,750,000	36,764,704
Increase (Decrease) in Temporary Equity
Accretion of Series A, Series B/B-1 and Series C convertible preferred stock to its redemption value	$ 1,688	$ 709	$ 23,990	$ 2,134					28,521
Conversion of Series A convertible preferred stock to common stock upon initial public offering	$ (25,026,061)								(25,026,061)
Conversion of Series A convertible preferred stock to common stock upon initial public offering (in shares)	(25,074,999)
Conversion of Series B convertible preferred stock to common stock upon initial public offering		$ (30,779,409)							(30,779,409)
Conversion of Series B convertible preferred stock to common stock upon initial public offering (in shares)		(30,800,000)
Conversion of Series B-1 convertible preferred stock to common stock upon initial public offering			$ (4,847,069)						(4,847,069)
Conversion of Series B-1 convertible preferred stock to common stock upon initial public offering (in shares)			(4,750,000)
Conversion of Series C convertible preferred stock to common stock upon initial public offering				$ (59,938,120)					(59,938,120)
Conversion of Series C convertible preferred stock to common stock upon initial public offering (in shares)				(36,764,704)
Balance at Dec. 31, 2013					$ 958	$ 697,283	$ (82,268,850)		(81,570,609)
Balance (in shares) at Dec. 31, 2013					957,756
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense						2,383,399			2,383,399
Exercise of stock options					$ 186	111,592			111,778
Exercise of stock options (in shares)					186,682
Accretion of Series A, Series B/B-1 and Series C convertible preferred stock to its redemption value						(28,521)			(28,521)
Conversion of Series A convertible preferred stock to common stock					$ 4,044	25,022,017			25,026,061
Conversion of Series A convertible preferred stock to common stock (in shares)					4,044,354
Conversion of Series B convertible preferred stock to common stock					$ 4,968	30,774,441			30,779,409
Conversion of Series B convertible preferred stock to common stock (in shares)					4,967,741
Conversion of Series B-1 convertible preferred stock to common stock					$ 766	4,846,303			4,847,069
Conversion of Series B-1 convertible preferred stock to common stock ( in shares)					766,129
Conversion of Series C convertible preferred stock to common stock					$ 5,930	59,932,190			59,938,120
Conversion of Series C convertible preferred stock to common stock (in shares)					5,929,789
Net conversion of preferred stock warrants common stock upon initial public offering (in shares)					20,273
Net conversion of preferred stock warrants common stock upon initial public offering					$ 20	(20)
Reclassification of convertible preferred stock warrant liability						145,256			145,256
Issuance of common stock warrants						1,000			1,000
Issuance of common stock, net of issuance costs					$ 22,369	107,267,954			107,290,323
Issuance of common stock (in shares)					22,368,449
Change in unrealized loss on marketable securities								$ (18,782)	(18,782)
Net loss							(49,700,875)		(49,700,875)
Balance at Dec. 31, 2014					$ 39,241	231,152,894	(131,969,725)	(18,782)	$ 99,203,628
Balance (in shares) at Dec. 31, 2014					39,241,173				39,241,173
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense						3,426,730			$ 3,426,730
Exercise of stock options					$ 384	905,403			905,787
Exercise of stock options (in shares)					384,033
Net exercise of common stock warrant					$ 2	(2)
Net exercise of common stock warrant (in shares)					2,397
Issuance of common stock warrants						4,000			4,000
Issuance of common stock, net of issuance costs					$ 11,175	90,295,459			90,306,634
Issuance of common stock (in shares)					11,175,000
Change in unrealized loss on marketable securities								(187,074)	(187,074)
Net loss			$ (50,528,240)				(50,528,240)		(50,528,240)
Balance at Dec. 31, 2015					$ 50,802	$ 325,784,484	$ (182,497,965)	$ (205,856)	$ 143,131,465
Balance (in shares) at Dec. 31, 2015					50,802,603				50,802,603

Statements of Cash Flows

Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net loss	$ (50,528,240)	$ (49,700,875)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	207,897	239,390
Stock-based compensation	3,426,730	2,383,399
Noncash interest expense on loans	179,747	33,442
Loss on disposal of assets	10,520	5,015
Revaluation of warrant liability	70,387	(122,412)
Amortization of bond premium on marketable securities	1,210,205
Changes in operating assets and liabilities:
Prepaid expenses, offering costs and other assets	(1,223,272)	3,196,559
Accounts payable and other liabilities	2,821,066	4,187,552
Deferred revenue	3,750,000
Net cash used in operating activities	(40,074,960)	(39,777,930)
Investing activities:
Purchase of property and equipment	(361,247)	(440,381)
Purchase of intangible asset	(15,000)
Purchases of marketable securities	(56,563,087)	(70,717,422)
Net cash provided by (used in) investing activities	(56,939,334)	(71,157,803)
Financing activities:
Proceeds from exercise of common stock options	905,787	111,778
Proceeds from loans payable, net	16,368,443	1,775,012
Proceeds from issuance of common stock, net	90,310,634	107,290,323
Capital lease payments	(2,563)	(1,019)
Net cash provided by financing activities	107,582,301	109,176,094
Net increase (decrease) in cash and cash equivalents	10,568,007	(1,759,639)
Cash and cash equivalents-beginning of period	36,205,559	37,965,198
Cash and cash equivalents-end of period	46,773,566	36,205,559
Supplemental disclosure of cash flow information:
Cash paid for interest	154,618	37,209
Capital lease additions		14,259
Common Stock
Supplemental disclosure of cash flow information:
Fair value of stock warrants issued	$ 4,000	$ 1,000

Organization and Description of

Organization and Description of the Business	12 Months Ended
	Dec. 31, 2015
Organization and Description of the Business
Organization and Description of the Business	1. Organization and Description of the Business Trevena, Inc. (the "Company") was incorporated in Delaware as Parallax Therapeutics, Inc. on November 9, 2007. The Company began operations in December 2007, and its name was changed to Trevena, Inc. on January 3, 2008. The Company is a clinical stage biopharmaceutical company that discovers, develops and intends to commercialize therapeutics that use a novel approach to target G protein coupled receptors. The Company operates in one segment and has its principal office in King of Prussia, Pennsylvania. The Company's revenue has been derived from research grants and a research collaboration with a pharmaceutical company. Liquidity At December 31, 2015, the Company had an accumulated deficit of $182.5 million. The net loss was $50.5 million and $49.7 million for the years ended December 31, 2015 and 2014, respectively. The Company expects its cash and cash equivalents of $46.8 million and marketable securities of $125.9 million as of December 31, 2015, together with interest thereon, to be sufficient to fund its operating expenses and capital expenditure requirements into 2018.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP"). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). The Company considers the U.S. dollar to be its functional currency. Use of Estimates Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements if these results differ from historical experience, or other assumptions do not turn out to be substantially accurate, even if such assumptions are reasonable when made. In preparing these financial statements, management used significant estimates in the following areas, among others: stock-based compensation expense, the determination of the fair value of stock-based awards, the fair value of liability-classified common stock warrants, and the accounting for research and development costs, accrued expenses and the recoverability of the Company's net deferred tax assets and related valuation allowance. Cash, Cash Equivalents, Investments and Concentration of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash, cash equivalents, marketable securities and restricted cash. The Company's investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company considers all highly liquid investments that have maturities of three months or less when acquired to be cash equivalents. Cash equivalents are valued at cost, which approximates their fair market value. The Company maintains a portion of its cash and cash equivalent balances in money market mutual funds that invest substantially all of their assets in U.S. government agency securities, U.S. Treasury securities reverse repurchase agreements, or RRAs. RRAs are collateralized by deposits in the form of 'Government Securities and Obligations' for an amount not less than 102% of their value. The Company does not record an asset or liability related to the collateral, as the Company is not permitted to sell or repledge the associated collateral. The Company maintains its marketable securities balances in the form of U.S. Treasury and U.S. government agency securities. The Company classifies its marketable securities as "available-for-sale", pursuant to ASC Topic 320, Investments—Debt and Equity Securities ("ASC 320"), carries them at fair market value and classifies them as current assets on its balance sheets. Unrealized gains and losses on marketable securities are recorded as a separate component of accumulated other comprehensive income/(loss) included in stockholders' equity. As of December 31, 2015 and 2014, the Company had $125.9 million and $70.7 million, respectively, in available-for-sale investments, all classified as current assets. See Note 3 for additional information. The fair value of our investments is determined based on observable market quotes or valuation models using assessments of counterparty credit worthiness, credit default risk of underlying security and overall capital market liquidity. The company reviews unrealized losses associated with available-for-sale securities to determine the classification as "temporary" or "other-than-temporary" impairment. A temporary impairment results in an unrealized loss being recorded in other comprehensive income. If a decline in the fair value is considered other-than-temporary, based on available evidence, the unrealized loss is transferred from other comprehensive loss to the statement of operations. The Company considers various factors in determining the classification, including the length of time and extent to which the fair value has been less than the Company's cost basis, the financial condition and near-term prospects of the issuer or investee, and the Company's ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. There were no charges taken for other-than-temporary declines in fair value of short-term or long-term investments during the years ended December 31, 2015 and 2014. The Company recorded unrealized losses of $187,074 and $18,782 during the years ended December 31, 2015 and 2014, respectively. Realized gains and losses are included in interest income in the statement of operations and comprehensive loss on a specific identification basis. The Company did not record any realized gains or losses during the years ended December 31, 2015 and 2014. The Company maintains a letter of credit totaling $112,000 as collateral for the Company's facility lease obligations in Pennsylvania and has recorded this and accumulated interest thereon as restricted cash on its balance sheet. Fair Value of Financial Instruments The carrying amount of the Company's financial instruments, which include cash and cash equivalents, marketable securities, restricted cash, accounts payable and accrued expenses approximate their fair values, given their short-term nature. The carrying amount of the Company's loans payable at December 31, 2015 and 2014 approximates fair value because the interest rate is reflective of the rate the Company could obtain on debt with similar terms and conditions. The common stock warrants are carried at fair value as disclosed below. The Company has evaluated the estimated fair value of financial instruments using available market information and management's estimates. The use of different market assumptions and/or estimation methodologies could have a significant effect on the estimated fair value amounts. See Note 3 for additional information. Property and Equipment Property and equipment consists of computer and laboratory equipment, software, office equipment, furniture and leasehold improvements and is recorded at cost. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed to operations as incurred. Upon disposal, retirement or sale the related cost and accumulated depreciation is removed from the accounts and any resulting gain or loss is included in the results of operations. Property and equipment are depreciated on a straight-line basis over their estimated useful lives. The Company uses a life of three years for computer equipment, and five years for laboratory equipment, office equipment, furniture and software. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the asset. The Company reviews long-lived assets when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparison of the book values of the assets to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets. No impairment losses have been recorded since inception. Intangible Asset Identifiable intangible assets are initially recorded at fair market value at the time of acquisition, utilizing a cost approach and the initial value is amortized over the expected useful life of the asset. The Company also capitalizes costs incurred to renew or extend the term of recognized intangible assets. In 2015, the Company recorded an intangible asset of $15,000 related to the Company website and expects to recognize approximately $1,875 in amortization over each of the next eight years. Amortization expense on intangible assets was $156 for the year ended December 31, 2015. The determination of the value of intangible assets requires management to make estimates and assumptions that affect the Company's consolidated financial statements. The Company assesses potential impairments to intangible assets when there is evidence of events or changes in circumstances that indicate the carrying amount of an asset may not be recovered. The Company's judgements regarding the existence of impairment indicators and future cash flows related to intangible assets are based on operational performance of our Company, market conditions and other factors. If impairment is indicated, the Company will reduce the carrying value of the intangible assets to fair value. The Company believes the future cash flows to be received from its intangible asset will exceed the intangible asset carrying value, and accordingly, the Company has not recognized any impairment losses through December 31, 2015. Common Stock Warrants Freestanding warrants that are related to the purchase of common stock are classified as liabilities and recorded at fair value regardless of the timing of the redemption feature or the redemption price or the likelihood of redemption. The warrants are subject to re-measurement at each balance sheet date and any change in fair value is recognized as a component of change in fair value of warrant liability in the statements of operations and comprehensive loss. The Company will continue to adjust the liability for changes in fair value until the earlier of the exercise or expiration of the warrants. The warrants are classified as Level 3 liabilities (see Note 3 for additional information). Segment Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, or decision-making group, in making decisions on how to allocate resources and assess performance. The Company's chief operating decision maker is the chief executive officer. The Company and the chief executive officer view the Company's operations and manage its business as one operating segment. All long-lived assets of the Company reside in the United States. Revenue The Company recognizes grant revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed and determinable, and collectibility is reasonably assured. The Company recognizes revenue under grants in earnings in the period in which the related expenditures are incurred. The Company recognizes collaboration revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed and determinable, and collectibility is reasonably assured. Research and Development Research and development costs are charged to expense as incurred. These costs include, but are not limited to, employee-related expenses, including salaries, benefits and travel and stock based compensation of our research and development personnel; expenses incurred under agreements with contract research organizations and investigative sites that conduct clinical trials and preclinical studies; the cost of acquiring, developing and manufacturing clinical trial materials; other laboratory supplies; allocated facilities, depreciation and other expenses, which include rent and utilities; insurance; and costs associated with preclinical activities and regulatory operations. Costs for certain development activities, such as clinical trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as subject enrollment, clinical site activations or information provided to the Company by its vendors with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the financial statements as prepaid or accrued research and development expense, as the case may be. As part of the process of preparing its financial statements, the Company is required to estimate its expenses resulting from its obligations under contracts with vendors, clinical research organizations and consultants and under clinical site agreements in connection with conducting clinical trials. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company's objective is to reflect the appropriate trial expenses in its financial statements by matching those expenses with the period in which services are performed and efforts are expended. The Company may account for these expenses according to the progress of the trial as measured by subject progression and the timing of various aspects of the trial. The Company determines accrual estimates through financial models taking into account discussion with applicable personnel and outside service providers as to the progress or state of consummation of trials, or the services completed. During the course of a clinical trial, the Company adjusts its clinical expense recognition if actual results differ from its estimates. The Company makes estimates of its accrued expenses as of each balance sheet date based on the facts and circumstances known to it at that time. The Company's clinical trial accruals are dependent upon the timely and accurate reporting of contract research organizations and other third party vendors. 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 it reporting amounts that are too high or too low for any particular period. For the years ended December 31, 2015 and 2014, there were no material adjustments to the Company's prior period estimates of accrued expenses for clinical trials. Stock-Based Compensation At December 31, 2015, the Company had one stock-based compensation plan, which is more fully described in Note 7. The Company accounts for stock-based compensation in accordance with the provisions of ASC Topic 718, Compensation—Stock Compensation ("ASC 718"), which requires the recognition of expense related to the fair value of stock-based compensation awards in the Statements of Operations and Comprehensive Loss. For stock options issued to employees and members of the Board for their services on the Board, the Company estimates the grant date fair value of each option using the Black-Scholes option-pricing model. The use of the Black- Scholes option pricing model requires management to make assumptions with respect to the expected term of the option, the expected volatility of the common stock consistent with the expected life of the option, risk-free interest rates, the value of the common stock and expected dividend yields of the common stock. For awards subject to service-based vesting conditions, the Company recognizes stock-based compensation expense, net of estimated forfeitures, equal to the grant date fair value of stock options on a straight-line basis over the requisite service period, which is generally the vesting term. For awards subject to both performance and service-based vesting conditions, the Company recognizes stock-based compensation expense using the accelerated attribution method when it is probable that the performance condition will be achieved. Forfeitures are required to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Share-based payments issued to non-employees are recorded at their fair values, and are periodically revalued as the equity instruments vest and are recognized as expense over the related service period in accordance with the provisions of ASC 718 and ASC Topic 505, Equity. See Note 7 for a discussion of the assumptions used by the Company in determining the grant date fair value of options granted under the Black-Scholes option pricing model, as well as a summary of the stock option activity under the Company's stock-based compensation plan for the years ended December 31, 2015 and 2014. Income Taxes Income taxes are recorded in accordance with ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided, if based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of December 31, 2015 and 2014, the Company does not have any significant uncertain tax positions. Comprehensive Loss Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive loss relates to unrealized investment losses on the Company's marketable securities for the years ended December 31, 2015 and 2014. Basic and Diluted Net Loss Per Share of Common Stock Basic net loss per share of common stock is computed by dividing net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, excluding the dilutive effects of preferred stock, warrants to purchase preferred stock and stock options. Diluted net loss per share of common stock is computed by dividing the net loss attributable to common stockholders by the sum of the weighted-average number of shares of common stock outstanding during the period plus the potential dilutive effects of preferred stock and warrants to purchase preferred stock, and stock options outstanding during the period calculated in accordance with the treasury stock method, although these shares, options and warrants are excluded if their effect is anti-dilutive. Because the impact of these items is anti-dilutive during periods of net loss, there was no difference between basic and diluted net loss per share of common stock for the years ended December 31, 2015 and 2014. Recent Accounting Pronouncements On April 7, 2015, the FASB issued Accounting Standards Update 2015-03, Simplifying the Presentation of Debt Issuance Costs ("ASU 2015-03"). ASU 2015-03 requires debt issuance costs to be presented in the balance sheets as a direct deduction from the associated debt liability. Although the standard is retrospectively effective for annual reporting periods beginning after December 15, 2015, early adoption is permitted for any annual reporting period or interim period for which the entity's financial statements have not yet been issued. The Company elected early adoption during the first quarter of 2015, which resulted in a balance sheet adjustment as of December 31, 2014 of $98,401 to other assets and loans payable, net. The Company's adoption of this standard had no impact on its results of operations or cash flows. See Note 6. In May 2014, the FASB issued Accounting Standards Update 2014-09 Revenue from Contracts with Customers ("ASU 2014-09"). ASU 2014-09 is a comprehensive new revenue recognition model requiring a company to recognize revenue to depict the transfer of goods or services to a customer in an amount reflecting the consideration it expects to receive in exchange for those goods or services. In July 2015, the FASB decided to defer the effective date of the standard from January 1, 2017, to January 1, 2018, with an option that permits companies to adopt the standard as early as the original effective date. Early application prior to the original effective date is not permitted. The standard permits the use of either the retrospective or cumulative effect transition method. We are evaluating the transition method we will elect. The adoption of this standard is not expected to have a material impact on the Company's financial statements.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2015
Fair Value of Financial Instruments
Fair Value of Financial Instruments	3. Fair Value of Financial Instruments ASC Topic 820, Fair Value Measurement ("ASC 820"), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company's own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company's assumptions about the inputs that market participants would use in pricing the asset or liability, and are developed based on the best information available in the circumstances. ASC 820 identifies fair value as the exchange price, or exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, ASC Topic 820 establishes a three-tier fair value hierarchy that distinguishes among the following: • Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access. • Level 2—Valuations based on quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active and models for which all significant inputs are observable, either directly or indirectly. • Level 3—Valuations based on inputs that are unobservable and significant to the overall fair value measurement. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument's level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Cash, Cash Equivalents and Marketable Securities All highly liquid investments that have maturities of three months or less when acquired are considered by the Company to be cash equivalents and are valued at cost, which approximates fair market value. The Company classifies its marketable securities as "available-for-sale", carries them at fair market value and classifies them as current assets on its balance sheets. Unrealized gains and losses on marketable securities are recorded as a separate component of accumulated other comprehensive income/(loss) included in stockholders' equity. There were no charges taken for other-than-temporary declines in fair value of investments during the years ended December 31, 2015 and 2014. The following table presents the Company's cash and available-for-sale securities' adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category recorded as cash and cash equivalents or marketable securities as of December 31, 2015 and 2014: December 31, 2015 Adjusted Cost Unrealized Gains Unrealized Losses Fair Value Cash and Cash Equivalents Marketable Securities Cash $ $ — $ — $ $ $ — Level 1(1): Money market funds — — — U.S. Treasury securities ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 2(2): Repurchase agreements — — — U.S. government agency securities ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ) $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2014 Adjusted Cost Unrealized Gains Unrealized Losses Fair Value Cash and Cash Equivalents Marketable Securities Cash $ $ — $ — $ $ $ — Level 1(1): Money market funds — — — U.S. Treasury securities ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ) $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The fair value of Level 1 securities is estimated based on quoted prices in active markets for identical assets or liabilities. (2) The fair value of Level 2 securities is estimated based on observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term on the assets or liabilities. As of December 31, 2015, the Company held $22.5 million of available-for-sale investment securities with contractual maturity dates of more than one year and less than two years. The Company did not hold any investment securities exceeding a two-year maturity. The Company recognizes transfers between levels of the fair value hierarchy as of the end of the reporting period. There were no transfers in or out of Level 3 in the hierarchy during the years ended December 31, 2015 or 2014. Warrant Liability At December 31, 2015, there is an outstanding warrant to purchase up to 20,161 shares of the Company's common stock with a fair value recorded as a liability of $153,238 as it contains a cash settlement feature upon certain strategic transactions. The following table sets forth a summary of changes in the fair value of this warrant liability, which represents a recurring measurement that is classified within Level 3 of the fair value hierarchy, wherein fair value is estimated using significant unobservable inputs: Warrant Liability Balance as of January 1, 2014 $ Amounts acquired or issued — Changes in estimated fair value ) Amounts reclassified to additional paid-in capital ) ​ ​ ​ ​ ​ Balance as of December 31, 2014 Amounts acquired or issued — Changes in estimated fair value ​ ​ ​ ​ ​ Balance as of December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ On each re-measurement date, the fair value of the warrant classified as a liability is estimated using the Black-Scholes option pricing model. For this liability, the Company develops its own assumptions that do not have observable inputs or available market data to support the fair value. This method of valuation involves using inputs such as the fair value of the Company's common stock, stock price volatility, the contractual term of the warrants, risk-free interest rates and dividend yields. Due to the nature of these inputs, the valuation of the warrants is considered a Level 3 measurement. The following assumptions were used at December 31, 2015 and 2014 to determine the warrant liability: December 31, 2015 2014 Common stock warrant liability Common stock warrant liability Estimated remaining term 6.3 years 7.3 years Risk-free interest rate % % Volatility % % Dividend yield % % Fair value of underlying instrument* $ $ * Trevena, Inc. closing stock price. The warrant liability is recorded on its own line item on the Company's balance sheets and is marked-to-market at each reporting period with the change in fair value recorded on its own line in the statements of operations and comprehensive loss. In connection with the issuance of debt, on September 19, 2014 and December 23, 2015, the Company issued to the lenders and the placement agent in the transaction warrants to purchase an aggregate of 42,639 shares of the Company's common stock. These detachable warrant instruments have qualified for equity classification and have been allocated upon the relative fair value of the base instrument and the warrants, according to the guidance of ASC 470-20-25-2. See Note 6 for additional information.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2015
Property and Equipment
Property and Equipment	4. Property and Equipment Property and equipment consisted of the following: December 31, 2015 2014 Laboratory equipment $ $ Computers and software Office equipment and furniture Leasehold improvements Leased assets ​ ​ ​ ​ ​ ​ ​ ​ Total property and equipment Less accumulated depreciation and amortization ) ) ​ ​ ​ ​ ​ ​ ​ ​ Property and equipment, net $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Depreciation and amortization expense was $207,897and $239,390 for the years ended December 31, 2015 and 2014, respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2015
Accrued Expenses and Other Current Liabilities
Accrued Expenses and Other Current Liabilities	5. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: December 31, 2015 2014 Compensation and benefits $ $ Clinical trial expenses Other research and development expenses — Other accrued expenses and other current liabilities ​ ​ ​ ​ ​ ​ ​ ​ Total accrued expenses and other current liabilities $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Loans Payable

Loans Payable	12 Months Ended
	Dec. 31, 2015
Loans Payable.
Loans Payable	6. Loans Payable In September 2014, the Company entered into a loan and security agreement with Oxford Finance LLC and Pacific Western Bank (formerly Square 1 Bank), or the lenders, pursuant to which the lenders agreed to lend the Company up to $35.0 million in a three-tranche series of term loans (Term Loans A, B, and C). Upon initially entering into the agreement, the Company borrowed $2.0 million under Term Loan A. On April 13, 2015, the Company amended the agreement with the lenders to change the draw period for Term Loan B. On December 23, 2015, the Company further amended the agreement with the lenders to, among other things, change the draw period for Term Loan C, modify the interest only period, and modify the maturity date of the loan. In December 2015, the Company borrowed the Term Loan B tranche of $16.5 million. The Company may now, at its sole discretion, borrow from the lenders an additional $16.5 million under Term Loan C, at any time on or before December 31, 2016, subject to the satisfaction of specified conditions related to the results of the Company's Phase 2b clinical trial of TRV027. The proceeds from Term Loan A and Term Loan B, and future proceeds, if any, from Term Loan C, may be used to satisfy the Company's future working capital needs, potentially including the development of its clinical and preclinical product candidates. Borrowings accrue interest at a fixed rate of 6.50% per annum. The Company is required to make payments of interest only on borrowings under the loan agreement on a monthly basis through and including January 1, 2017 (the interest only termination date), after which payments of principal in equal monthly installments and accrued interest will be due until the loan matures on March 1, 2020. Both the interest only termination date and the maturity date may be further modified as follows if the Company meet the conditions related to the Phase 2b trial of TRV027 by December 31, 2016: • the interest only termination date will be extended until January 1, 2018, and • the maturity date will be extended to December 1, 2020 if the Company also has received net cash proceeds of at least $50.0 million from its existing option and license with Allergan or another strategic partnership satisfactory to the lenders. The Company paid the lenders a facility fee of $175,000 in connection with the execution of the original agreement and an amendment fee of $20,000 in connection with the execution of the second amendment to the agreement. Upon the last payment date of the amounts borrowed under the agreement, the Company will be required to pay a final payment fee ranging from 6.1% to 7.0% of the aggregate amounts borrowed. In addition, if the Company repays Term Loan A and Term Loan B prior to the applicable maturity date, it will pay the Lenders a prepayment fee of 3.00% of the total amount prepaid if the prepayment occurs prior to December 23, 2016, 2.00% percent of the total amount prepaid if the prepayment occurs between December 23, 2016 and December 23, 2017, and 1.00% percent of the total amount prepaid if the prepayment occurs on or after December 24, 2017. The Company's obligations under the loan and security agreement are secured by a first priority security interest in substantially all of the assets of the Company, other than intellectual property. The Company has agreed not to pledge or otherwise encumber its intellectual property, other than through grants of certain permitted non-exclusive or exclusive licenses or other conveyances of its intellectual property. The loan and security agreement includes affirmative and restrictive covenants, including: (a) financial reporting requirements; (b) limitations on the incurrence of indebtedness; (c) limitations on liens; (d) limitations on certain merger and acquisition transactions; (e) limitations on dispositions of certain assets; (f) limitations on fundamental corporate changes (including changes in control); (g) limitations on investments; (h) limitations on payments and distributions and (i) other covenants. The agreement also contains certain events of default, including for payment defaults, breaches of covenants, a material adverse change in the collateral, the Company's business, operations or condition (financial or otherwise), certain levies, attachments and other restraints on the Company's business, insolvency, defaults under other agreements and misrepresentations. Three Point Capital, LLC served as a placement agent in connection with the term loans. The Company paid the agent $65,000 upon execution of the agreement and $87,500 upon its draw of Term Loan B; the Company will be obligated to pay up to an additional $87,500 if it draws on Term Loan C. In connection with entering into the agreement, the Company issued to the lenders and the placement agent warrants to purchase an aggregate of 7,678 shares of Trevena common stock. These detachable warrant instruments have qualified for equity classification and have been allocated upon the relative fair value of the base instrument and the warrants, according to the guidance of ASC 470-20-25-2. These warrants are exercisable immediately and have an exercise price of $5.8610 per share. The warrants may be exercised on a cashless basis and will terminate on the earlier of September 19, 2024 or the closing of a merger or consolidation transaction in which the Company is not the surviving entity. In connection with the draw of Term Loan B, the Company issued to the lenders and the placement agent additional warrants to purchase an aggregate of 34,961 shares of Trevena common stock. These warrants have substantially the same terms as those noted above, have an exercise price of $10.6190 per share and an expiration date of December 23, 2025. If the Company draws on Term Loan C, it will issue additional warrants to purchase shares of Trevena common stock on substantially the same terms as those contained in the initial warrants. The number of shares underlying these additional warrants will depend on the amount of additional borrowings. As of December 31, 2015, Term Loans A and B have been issued, all of which remains outstanding as of such date. Interest expense of $164,667 and $36,833 was recorded during the years ended December 31, 2015 and 2014, respectively. The Company incurred lender and third party costs of $225,988 and $106,545, respectively, related to the issuance of Term Loan A. The Company incurred lender and third party costs of $44,058 and $87,500, respectively, related to the issuance of Term Loan B. The lender costs are classified as a debt discount and the third party costs are classified as debt issuance costs. Per ASU 2015-03, debt discount and debt issuance costs are to be presented as a contra-liability to the debt on the balance sheet. These costs will be amortized to interest expense over the life of Term Loan A using the effective interest method. A total of $124,572 and $25,417 of debt discount and debt issuance costs was amortized to interest expense during the years ended December 31, 2015 and 2014, respectively. The following table summarizes how the issuance of Term Loans A and B are reflected on the balance sheet at December 31, 2015: December 31, 2015 Gross proceeds $ Debt discount ) Debt issuance costs ) ​ ​ ​ ​ ​ Carrying value $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Aggregate maturities of long term debt as of December 31, 2015 are as follows: 2016 — 2017 2018 2019 2020 ​ ​ ​ ​ ​ Debt Discount and deferred financing costs ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity
Stockholders' Equity	7. Stockholders' Equity Equity Offerings On September 16, 2015, the Company issued and sold 7,475,000 shares of common stock in a public offering at a price of $9.75 per share, for gross proceeds of approximately $72.9 million. The net offering proceeds to the Company were approximately $68.3 million, after deducting underwriting discounts and commissions of approximately $4.4 million and offering costs of $0.2 million. On July 7, 2015, the Company issued and sold 1,000,000 shares of common stock through Cowen and Company, LLC (Cowen), pursuant to an at-the-market (ATM) sales facility dated April 3, 2015. The shares were sold at a weighted average price per share of $6.0001, for aggregate gross proceeds of $6.0 million. The net offering proceeds to the Company were approximately $5.8 million after deducting related expenses, including commissions of approximately $0.2 million. On May 8, 2015, the Company issued and sold 2,700,000 shares of common stock through Cowen pursuant to the ATM facility at a weighted average price per share of $6.2503, for aggregate gross proceeds of $16.9 million. The net offering proceeds to the Company were approximately $16.2 million after deducting related expenses, including commissions of approximately $0.5 million. On December 10, 2014, the Company issued and sold 11,250,000 shares of common stock in a public offering of shares as well as 1,598,000 shares of common stock pursuant to the partial exercise of the underwriters' over-allotment option for a total of 12,848,000 shares at a price of $4.00 per share, for aggregate gross proceeds of approximately $51.4 million. On February 5, 2014, the Company issued and sold 9,250,000 shares of common stock in an IPO at a price of $7.00 per share, for aggregate gross proceeds of approximately $64.8 million. On March 6, 2014, in connection with the partial exercise of the IPO underwriters' over-allotment option, the Company sold an additional 270,449 shares of common stock at a price of $7.00 per share, for aggregate gross proceeds of approximately $1.9 million. Under its certificate of incorporation, the Company was authorized to issue up to 100,000,000 shares of common stock as of December 31, 2015 and December 31, 2014, respectively. The Company also was authorized to issue up to 5,000,000 shares of preferred stock as of December 31, 2015. The Company is required, at all times, to reserve and keep available out of its authorized but unissued shares of common stock sufficient shares to effect the conversion of the shares of the preferred stock and all outstanding stock options and warrants. Equity Incentive Plans In 2008, the Company adopted the 2008 Equity Incentive Plan, as amended on February 29, 2008, January 7, 2010, July 8, 2010, December 10, 2010, June 23, 2011 and June 17, 2013 (collectively, the "2008 Plan") that authorized the Company to grant restricted stock and stock options to eligible employees, directors and consultants to the Company. In 2013, the Company adopted the 2013 Equity Incentive Plan, as amended on May 14, 2014 (collectively, the "2013 Plan"). The 2013 Plan became effective upon the Company's entry into the underwriting agreement related to its initial public offering (IPO) in January 2014 and, as of such date, the Company may not make further grants under the 2008 Plan. The 2013 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance-based stock awards and other forms of equity compensation (collectively, stock awards), all of which may be granted to employees, including officers, non-employee directors and consultants of the Company. Additionally, the 2013 Plan provides for the grant of cash and stock based performance awards. The 2013 Plan contains an "evergreen" provision, pursuant to which the number of shares of common stock available for issuance under the plan automatically increases on January 1 of each year beginning in 2015. Under both the 2008 and 2013 Plans, the amount, terms of grants and exercisability provisions are determined by the board of directors or its designee. The term of the options may be up to 10 years, and options are exercisable in cash or as otherwise determined by the board of directors. Vesting generally occurs over a period of not greater than four years. The estimated grant-date fair value of the Company's share-based awards is amortized ratably over the awards' service periods. Share-based compensation expense recognized was as follows: Year Ended December 31, 2015 2014 Research and development $ $ General and administrative ​ ​ ​ ​ ​ ​ ​ ​ Total stock-based compensation $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding Number of Shares Weighted- Average Exercise Price Weighted Average Remaining Contractual Term (in years) Balance, December 31, 2013 $ Granted Exercised ) Forfeitures ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2014 $ Granted Exercised ) Forfeitures ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Vested or expected to vest at December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Exercisable at December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The intrinsic value of the options exercisable as of December 31, 2015 was $14.4 million, based on the Company's closing stock price of $10.50 per share and a weighted average exercise price of $3.10 per share. The Company uses the Black-Scholes option-pricing model to estimate the fair value of stock options at the grant date. The Black-Scholes model requires the Company to make certain estimates and assumptions, including estimating the fair value of the Company's common stock, assumptions related to the expected price volatility of the Company's stock, the period during which the options will be outstanding, the rate of return on risk-free investments and the expected dividend yield for the Company's stock. The per-share weighted-average grant date fair value of the options granted to employees and directors during the year ended December 31, 2015 and 2014 was estimated at $4.49 and $4.43 per share, respectively, on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions: Year Ended December 31, 2015 Year Ended December 31, 2014 Expected term of options (in years) Risk-free interest rate % % Expected volatility % % Dividend yield % % The weighted-average valuation assumptions were determined as follows: • Risk-free interest rate: The Company based the risk-free interest rate on the interest rate payable on U.S. Treasury securities in effect at the time of grant for a period that is commensurate with the assumed expected option term. • Expected term of options: Due to its lack of sufficient historical data, the Company estimates the expected life of its employee stock options using the "simplified" method, as prescribed in Staff Accounting Bulletin (SAB) No. 107, whereby the expected life equals the arithmetic average of the vesting term and the original contractual term of the option. • Expected stock price volatility: The Company estimated the expected volatility based on actual historical volatility of the stock price of similar companies with publicly-traded equity securities. The Company calculated the historical volatility of the selected companies by using daily closing prices over a period of the expected term of the associated award. The companies were selected based on their enterprise value, risk profiles, position within the industry and with historical share price information sufficient to meet the expected term of the associated award. A decrease in the selected volatility would have decreased the fair value of the underlying instrument. • Expected annual dividend yield: The Company estimated the expected dividend yield based on consideration of its historical dividend experience and future dividend expectations. The Company has not historically declared or paid dividends to stockholders. Moreover, it does not intend to pay dividends in the future, but instead expects to retain any earnings to invest in the continued growth of the business. Accordingly, the Company assumed an expected dividend yield of 0.0%. • Estimated forfeiture rate: The Company's estimated annual forfeiture rate on 2015 and 2014 stock option grants was 9% and 7%, respectively, based on the historical forfeiture experience. The fair value of the Company's common stock, prior to the IPO, was determined by its board of directors with assistance from its management. The board of directors and management considered numerous objective and subjective factors in the assessment of fair value, including the price for the Company's preferred stock that was sold to investors and the rights, preferences and privileges of the preferred stock and common stock, the Company's financial condition and results of operations during the relevant periods and the status of strategic initiatives. These estimates involved a significant level of judgment. As of December 31, 2015, there was $9.0 million of total unrecognized compensation expense related to unvested options that will be recognized over the weighted average remaining period of 2.76 years. Shares Available for Future Grant At December 31, 2015, the Company has the following shares available to be granted under the 2013 Plan: Available at December 31, 2014 Authorized Granted ) Forfeitures/Expirations ​ ​ ​ ​ ​ Available at December 31, 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares Reserved for Future Issuance At December 31, 2015, the Company has reserved the following shares of common stock for issuance: Stock options outstanding Shares available for future grant under 2013 Plan Employee stock purchase plan Warrants outstanding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies.
Commitments and Contingencies	8. Commitments and Contingencies Licenses On May 3, 2013, the Company entered into an option agreement and a license agreement with Allergan plc (formerly Actavis plc and Forest Laboratories Holdings Limited), under which the Company granted to Allergan an exclusive option to license its product candidate, TRV027. If Allergan exercises this option, the license agreement between the Company and Allergan will become effective and Allergan will have an exclusive worldwide license to develop and commercialize TRV027 and specified related compounds. At the Company's request, Allergan will consider in good faith whether to grant the Company the right to co-promote the licensed products in the United States under terms to be agreed upon by the parties. Allergan will be responsible for subsequent development, regulatory approval and commercialization of TRV027 at Allergan's sole cost and expense. Under the option agreement, the Company is conducting, at its expense, a Phase 2b trial of TRV027 in acute heart failure, or AHF. In March 2015, Allergan and the Company signed a letter agreement pursuant to which Allergan paid the Company $10.0 million to fund the expansion of the Phase 2b trial of TRV027 from 500 patients to 620 patients. As part of this agreement, the Company and Allergan agreed to certain testing and analysis with respect to the study. The extended Phase 2b trial and related analysis are currently expected to be completed in the second quarter of 2016. Collaboration revenue will be recognized on a straight line basis over the study period. At the end of each reporting period, the Company will reassess the trial completion date and adjust the recognition period if necessary. The March 2015 letter agreement does not otherwise amend the terms of the May 2013 option agreement. Allergan may exercise its option during the pendency of the Phase 2b clinical trial or during a specified time period after the Company delivers the data from the Phase 2b clinical trial to Allergan. During the option period, the Company is not permitted to negotiate for or enter into any agreement with a third party for the development and commercialization of TRV027 and its related compounds. Under specified circumstances linked to adverse changes in the market or related to the results from the Phase 2b trial of TRV027, Allergan has the right to renegotiate the terms of the license agreement. If Allergan exercises such right, the Company will be obligated to negotiate in good faith with Allergan for a period of time the terms of any new arrangement. If the Company and Allergan are unable to agree on the terms of any new arrangement, then the option agreement will terminate and for a specified period of time thereafter the Company may not offer a license to any third party on terms better than those last proposed by either the Company or Allergan during the negotiations. If Allergan does not exercise its option during the specified period, the option will expire and the license agreement will not become effective. In that case, the Company would be free to enter into a collaboration arrangement with another party for the development and commercialization of TRV027 or to pursue development and commercialization on its own. The Company received no consideration upon the grant of the option to Allergan. If Allergan exercises the option, the Company would receive a $65.0 million option exercise fee and could potentially receive up to an additional $365.0 million depending upon the achievement of future development and commercial milestones. The Company also could receive tiered royalties between 10% and 20% on net sales of licensed products worldwide, with the royalty rates on net sales of licensed products in the United States being somewhat higher than the royalty rates on net sales of licensed products outside the United States. The term of the royalty on sales of TRV027 for a given country would extend until the latest to occur of (i) 10 years from first commercial sale of TRV027 in that country, (ii) the expiration of the last to expire patent claiming TRV027 that is sufficient to block the entrance of a generic version of the product, or (iii) the expiration of any period of exclusivity granted by applicable law or any regulatory authority in such country that confers exclusive marketing rights on the product. If the license agreement becomes effective, Allergan has the right to grant sublicenses under the license agreement to affiliates and third parties. Any sublicensing does not act to relieve Allergan of any of its obligations under the license agreement, including Allergan's obligation to make milestone payments to the Company with respect to TRV027 or pay royalties to the Company on sales of TRV027 by such sublicensee. Under the license, both Allergan and the Company have the right to terminate the agreement in the event of an uncured material breach or insolvency of the other party. In addition, Allergan is permitted to terminate the license agreement without cause at any time upon prior written notice or immediately for product safety reasons. Following a termination of the license agreement, all licenses granted to Allergan would terminate, and Allergan would grant the Company an exclusive royalty-bearing license under specified patents and know-how to develop and commercialize reverted licensed products. If not terminated, the license agreement would remain in effect until the expiration of the last royalty term for the last licensed product. Operating Leases The Company leases office and laboratory space in Pennsylvania. The Company's leases contain escalating rent clauses, which require higher rent payments in future years. The Company expenses rent on a straight-line basis over the term of the lease, including any rent-free periods. In July 2013, the Company extended the lease for the Company's office and laboratory lease in Pennsylvania until September 2020. In 2014 and 2015, the Company extended the square footage of the lease. The Company has the option to terminate the lease after May 31, 2018 with a required termination payment of $150,000. In addition, the Company leases vivarium space in Pennsylvania. The vivarium lease can be terminated at any time upon 90 days' written notice by the Company. Rent expense under operating leases was $589,762 and $489,810 in 2015 and 2014, respectively. Future minimum lease payments, including termination fees, under noncancelable lease agreements as of December 31, 2015, are as follows: Operating Lease 2016 $ 2017 2018 2019 2020 and beyond ​ ​ ​ ​ ​ Total minimum lease payments $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Company had deferred rent of $282,824 and $320,244 at December 31, 2015 and 2014, respectively. This balance related entirely to the Pennsylvania office and laboratory lease. Legal Proceedings The Company is not involved in any legal proceeding that it expects to have a material effect on its business, financial condition, results of operations and cash flows.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2015
Revenue
Revenue	9. Revenue For the year ended December 31, 2015, the Company recognized collaboration revenue of $6.3 million related to its March 2015 letter agreement with Allergan. The terms of this agreement contain multiple deliverables which include (i) research and development activities and (ii) testing and analysis related to the ongoing Phase 2b trial of TRV027 in exchange for a nonrefundable upfront fee of $10.0 million. Collaboration revenue is recognized only when the price is fixed or determinable, persuasive evidence of an arrangement exists, delivery has occurred or the services have been rendered and the Company has fulfilled its performance obligations under the contract. For arrangements with multiple elements, the Company recognizes revenue in accordance with the FASB's Accounting Standards Update No. 2009-13, Multiple-Deliverable Revenue Arrangements ("ASU 2009-13"), which provides guidance for separating and allocating consideration in a multiple element arrangement. Deliverables under the arrangement are separate units of accounting if the delivered item has value to the customer on a standalone basis and if the arrangement includes a general right of return relative to the delivery or performance of the undelivered item is considered probable and substantially within the Company's control. The consideration that is fixed or determinable at the inception of the arrangement is allocated to the separate units of accounting based on their relative selling prices. Management exercises significant judgement in determining whether a deliverable is a separate unit of accounting. In determining the separate units of accounting, the Company evaluates whether the components have standalone value to the collaborator based on consideration of the relevant facts and circumstances for each arrangements. Whenever the Company determines that an element is delivered over a period of time, revenue is recognized using either a proportional performance model, if a pattern of performance can be determined, or a straight-line model over the period of performance, which is typically the research and development term.

Net Loss Per Common Share

Net Loss Per Common Share	12 Months Ended
	Dec. 31, 2015
Net Loss Per Common Share
Net Loss Per Common Share	10. Net Loss Per Common Share The following table sets forth the computation of basic and diluted net loss per share for the periods indicated: Year Ended December 31, 2015 2014 Basic and diluted net loss per common share calculation: Net loss $ ) $ ) Accretion of redeemable convertible preferred stock — ) ​ ​ ​ ​ ​ ​ ​ ​ Net loss attributable to common stockholders $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average common shares outstanding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share of common stock—basic and diluted $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following outstanding securities at December, 31, 2015 and 2014 have been excluded from the computation of diluted weighted shares outstanding, as they would have been anti-dilutive: December 31, 2015 2014 Options outstanding Warrants ​ ​ ​ ​ ​ ​ ​ ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Comprehensive Loss

Comprehensive Loss	12 Months Ended
	Dec. 31, 2015
Comprehensive Loss
Comprehensive Loss	11. Comprehensive Loss The following table presents changes in the components of accumulated other comprehensive income or loss, net of tax: Balance, January 1, 2014 $ — Net unrealized loss arising during the period ​ ​ ​ ​ ​ Balance, December 31, 2014 $ Net unrealized loss arising during the period ​ ​ ​ ​ ​ Balance, December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ There were no reclassifications out of accumulated other comprehensive income or loss during the years ended December 31, 2015 and 2014. There was no tax effect during the years ended December 31, 2015 and 2014.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Taxes
Income Taxes	12. Income Taxes The Company provides for income taxes under ASC 740. Under ASC 740, the liability method is used in accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities, and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company has not recorded a current or deferred income tax expense or benefit since its inception. The Company's loss before income taxes was $50.5 million and $49.7 million for the years ended December 31, 2015 and 2014, respectively, and was generated entirely in the United States. Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The significant components of the Company's deferred tax assets are the following: December 31, 2015 2014 Deferred tax assets: Net operating loss carryforwards $ $ Research and development credits Research and development expenses capitalized for tax purposes Deferred rent Depreciation Other temporary differences ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax assets Deferred tax liabilities: Prepaid expenses ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax assets Less valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax asset $ — $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets. Based on the Company's history of operating losses since inception, the Company has concluded that it is more likely than not that the benefit of its deferred tax assets will not be realized. Accordingly, the Company has provided a full valuation allowance for deferred tax assets as of December 31, 2015 and 2014. The valuation allowance increased by $22.4 million and $22.1 million during the years ended December 31, 2015 and 2014, respectively, due primarily to the generation of net operating losses during the periods. A reconciliation of income tax expense computed at the statutory federal income tax rate to income taxes as reflected in the financial statements is as follows: December 31, 2015 2014 Percent of pre-tax income: U.S. federal statutory income tax rate % % Permanent Differences % )% State taxes, net of federal benefit % % Research and development credit % % Other % — Change in valuation allowance )% )% ​ ​ ​ ​ ​ ​ ​ ​ Effective income tax rate % % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2015 and 2014, the Company had U.S. federal net operating loss carryforwards of $28.7 million and $22.8 million, respectively, which may be available to offset future income tax liabilities and will begin to expire at various dates starting in 2027. As of December 31, 2015 and 2014, the Company also had U.S. state net operating loss carryforwards of $28.7 million and $22.8 million, respectively, which may be available to offset future income tax liabilities and will begin to expire at various dates starting in 2027. As of December 31, 2015 and 2014, the Company had federal research and development tax credit carryforwards of $6.8 million and $4.7 million, respectively, available to reduce future tax liabilities which will begin to expire at various dates starting in 2027. Under the provisions of the Internal Revenue Code, the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50 percent, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has completed several financings since its inception which may have resulted in a change in control as defined by Sections 382 and 383 of the Internal Revenue Code, or could result in a change in control in the future. The Company will recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2015 and 2014, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company's statements of operations and comprehensive loss. For all years through December 31, 2015, the Company generated research credits but has not conducted a study to document the qualified activities. This study may result in an adjustment to the Company's research and development credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position for these years. A full valuation allowance has been provided against the Company's research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carryforwards and the valuation allowance. The Protecting Americans from Tax Hikes Act of 2015, enacted December 18, 2015, permanently extends the research and development credit. The Company recorded a credit of $2.4 million for 2015. The Tax Increase Prevention Act of 2014, enacted December 19, 2014, reinstated the research and development credit through December 31, 2014, and the Company recorded a credit of $1.8 million for 2014. The Company files income tax returns in the United States, and various state jurisdictions. The federal and state income tax returns are generally subject to tax examinations for the tax years ended December 31, 2011 through December 31, 2014. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service or state tax authorities to the extent utilized in a future period.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2015
Employee Benefit Plan
Employee Benefit Plan	13. Employee Benefit Plan The Company sponsors a 401(k) defined contribution plan for its employees. Employee contributions are voluntary. The Company matches employee contributions in an amount equal to 100% of the first 3% of eligible compensation and 50% of the next 2% of eligible compensation, and such employer contributions are immediately vested. During 2015 and 2014, the Company provided matching contributions of $319,282 and $204,537, respectively.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events
Subsequent Events	14. Subsequent Events In February 2016, the Company issued and sold 1,350,755 shares of common stock through Cowen, pursuant to an at-the-market (ATM) sales facility dated April 3, 2015. The shares were sold at a weighted average price per share of $9.00. The net offering proceeds to the Company were approximately $11.8 million after deducting related expenses, including commissions.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP"). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). The Company considers the U.S. dollar to be its functional currency.
Use of Estimates	Use of Estimates Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements if these results differ from historical experience, or other assumptions do not turn out to be substantially accurate, even if such assumptions are reasonable when made. In preparing these financial statements, management used significant estimates in the following areas, among others: stock-based compensation expense, the determination of the fair value of stock-based awards, the fair value of liability-classified common stock warrants, and the accounting for research and development costs, accrued expenses and the recoverability of the Company's net deferred tax assets and related valuation allowance.
Cash, Cash Equivalents, Investments And Concentration Of Credit Risk And Off Balance Sheet Risk	Cash, Cash Equivalents, Investments and Concentration of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash, cash equivalents, marketable securities and restricted cash. The Company's investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company considers all highly liquid investments that have maturities of three months or less when acquired to be cash equivalents. Cash equivalents are valued at cost, which approximates their fair market value. The Company maintains a portion of its cash and cash equivalent balances in money market mutual funds that invest substantially all of their assets in U.S. government agency securities, U.S. Treasury securities reverse repurchase agreements, or RRAs. RRAs are collateralized by deposits in the form of 'Government Securities and Obligations' for an amount not less than 102% of their value. The Company does not record an asset or liability related to the collateral, as the Company is not permitted to sell or repledge the associated collateral. The Company maintains its marketable securities balances in the form of U.S. Treasury and U.S. government agency securities. The Company classifies its marketable securities as "available-for-sale", pursuant to ASC Topic 320, Investments—Debt and Equity Securities ("ASC 320"), carries them at fair market value and classifies them as current assets on its balance sheets. Unrealized gains and losses on marketable securities are recorded as a separate component of accumulated other comprehensive income/(loss) included in stockholders' equity. As of December 31, 2015 and 2014, the Company had $125.9 million and $70.7 million, respectively, in available-for-sale investments, all classified as current assets. See Note 3 for additional information. The fair value of our investments is determined based on observable market quotes or valuation models using assessments of counterparty credit worthiness, credit default risk of underlying security and overall capital market liquidity. The company reviews unrealized losses associated with available-for-sale securities to determine the classification as "temporary" or "other-than-temporary" impairment. A temporary impairment results in an unrealized loss being recorded in other comprehensive income. If a decline in the fair value is considered other-than-temporary, based on available evidence, the unrealized loss is transferred from other comprehensive loss to the statement of operations. The Company considers various factors in determining the classification, including the length of time and extent to which the fair value has been less than the Company's cost basis, the financial condition and near-term prospects of the issuer or investee, and the Company's ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. There were no charges taken for other-than-temporary declines in fair value of short-term or long-term investments during the years ended December 31, 2015 and 2014. The Company recorded unrealized losses of $187,074 and $18,782 during the years ended December 31, 2015 and 2014, respectively. Realized gains and losses are included in interest income in the statement of operations and comprehensive loss on a specific identification basis. The Company did not record any realized gains or losses during the years ended December 31, 2015 and 2014. The Company maintains a letter of credit totaling $112,000 as collateral for the Company's facility lease obligations in Pennsylvania and has recorded this and accumulated interest thereon as restricted cash on its balance sheet.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amount of the Company's financial instruments, which include cash and cash equivalents, marketable securities, restricted cash, accounts payable and accrued expenses approximate their fair values, given their short-term nature. The carrying amount of the Company's loans payable at December 31, 2015 and 2014 approximates fair value because the interest rate is reflective of the rate the Company could obtain on debt with similar terms and conditions. The common stock warrants are carried at fair value as disclosed below. The Company has evaluated the estimated fair value of financial instruments using available market information and management's estimates. The use of different market assumptions and/or estimation methodologies could have a significant effect on the estimated fair value amounts. See Note 3 for additional information.
Property and Equipment	Property and Equipment Property and equipment consists of computer and laboratory equipment, software, office equipment, furniture and leasehold improvements and is recorded at cost. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed to operations as incurred. Upon disposal, retirement or sale the related cost and accumulated depreciation is removed from the accounts and any resulting gain or loss is included in the results of operations. Property and equipment are depreciated on a straight-line basis over their estimated useful lives. The Company uses a life of three years for computer equipment, and five years for laboratory equipment, office equipment, furniture and software. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the asset. The Company reviews long-lived assets when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparison of the book values of the assets to future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value, which is measured based on the projected discounted future net cash flows arising from the assets. No impairment losses have been recorded since inception.
Intangible Asset	Intangible Asset Identifiable intangible assets are initially recorded at fair market value at the time of acquisition, utilizing a cost approach and the initial value is amortized over the expected useful life of the asset. The Company also capitalizes costs incurred to renew or extend the term of recognized intangible assets. In 2015, the Company recorded an intangible asset of $15,000 related to the Company website and expects to recognize approximately $1,875 in amortization over each of the next eight years. Amortization expense on intangible assets was $156 for the year ended December 31, 2015. The determination of the value of intangible assets requires management to make estimates and assumptions that affect the Company's consolidated financial statements. The Company assesses potential impairments to intangible assets when there is evidence of events or changes in circumstances that indicate the carrying amount of an asset may not be recovered. The Company's judgements regarding the existence of impairment indicators and future cash flows related to intangible assets are based on operational performance of our Company, market conditions and other factors. If impairment is indicated, the Company will reduce the carrying value of the intangible assets to fair value. The Company believes the future cash flows to be received from its intangible asset will exceed the intangible asset carrying value, and accordingly, the Company has not recognized any impairment losses through December 31, 2015.
Common Stock Warrants	Common Stock Warrants Freestanding warrants that are related to the purchase of common stock are classified as liabilities and recorded at fair value regardless of the timing of the redemption feature or the redemption price or the likelihood of redemption. The warrants are subject to re-measurement at each balance sheet date and any change in fair value is recognized as a component of change in fair value of warrant liability in the statements of operations and comprehensive loss. The Company will continue to adjust the liability for changes in fair value until the earlier of the exercise or expiration of the warrants. The warrants are classified as Level 3 liabilities (see Note 3 for additional information).
Segment Information	Segment Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, or decision-making group, in making decisions on how to allocate resources and assess performance. The Company's chief operating decision maker is the chief executive officer. The Company and the chief executive officer view the Company's operations and manage its business as one operating segment. All long-lived assets of the Company reside in the United States.
Revenue	Revenue The Company recognizes grant revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed and determinable, and collectibility is reasonably assured. The Company recognizes revenue under grants in earnings in the period in which the related expenditures are incurred. The Company recognizes collaboration revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed and determinable, and collectibility is reasonably assured.
Research and Development	Research and Development Research and development costs are charged to expense as incurred. These costs include, but are not limited to, employee-related expenses, including salaries, benefits and travel and stock based compensation of our research and development personnel; expenses incurred under agreements with contract research organizations and investigative sites that conduct clinical trials and preclinical studies; the cost of acquiring, developing and manufacturing clinical trial materials; other laboratory supplies; allocated facilities, depreciation and other expenses, which include rent and utilities; insurance; and costs associated with preclinical activities and regulatory operations. Costs for certain development activities, such as clinical trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as subject enrollment, clinical site activations or information provided to the Company by its vendors with respect to their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected in the financial statements as prepaid or accrued research and development expense, as the case may be. As part of the process of preparing its financial statements, the Company is required to estimate its expenses resulting from its obligations under contracts with vendors, clinical research organizations and consultants and under clinical site agreements in connection with conducting clinical trials. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided under such contracts. The Company's objective is to reflect the appropriate trial expenses in its financial statements by matching those expenses with the period in which services are performed and efforts are expended. The Company may account for these expenses according to the progress of the trial as measured by subject progression and the timing of various aspects of the trial. The Company determines accrual estimates through financial models taking into account discussion with applicable personnel and outside service providers as to the progress or state of consummation of trials, or the services completed. During the course of a clinical trial, the Company adjusts its clinical expense recognition if actual results differ from its estimates. The Company makes estimates of its accrued expenses as of each balance sheet date based on the facts and circumstances known to it at that time. The Company's clinical trial accruals are dependent upon the timely and accurate reporting of contract research organizations and other third party vendors. 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 it reporting amounts that are too high or too low for any particular period. For the years ended December 31, 2015 and 2014, there were no material adjustments to the Company's prior period estimates of accrued expenses for clinical trials.
Stock-Based Compensation	Stock-Based Compensation At December 31, 2015, the Company had one stock-based compensation plan, which is more fully described in Note 7. The Company accounts for stock-based compensation in accordance with the provisions of ASC Topic 718, Compensation—Stock Compensation ("ASC 718"), which requires the recognition of expense related to the fair value of stock-based compensation awards in the Statements of Operations and Comprehensive Loss. For stock options issued to employees and members of the Board for their services on the Board, the Company estimates the grant date fair value of each option using the Black-Scholes option-pricing model. The use of the Black- Scholes option pricing model requires management to make assumptions with respect to the expected term of the option, the expected volatility of the common stock consistent with the expected life of the option, risk-free interest rates, the value of the common stock and expected dividend yields of the common stock. For awards subject to service-based vesting conditions, the Company recognizes stock-based compensation expense, net of estimated forfeitures, equal to the grant date fair value of stock options on a straight-line basis over the requisite service period, which is generally the vesting term. For awards subject to both performance and service-based vesting conditions, the Company recognizes stock-based compensation expense using the accelerated attribution method when it is probable that the performance condition will be achieved. Forfeitures are required to be estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Share-based payments issued to non-employees are recorded at their fair values, and are periodically revalued as the equity instruments vest and are recognized as expense over the related service period in accordance with the provisions of ASC 718 and ASC Topic 505, Equity. See Note 7 for a discussion of the assumptions used by the Company in determining the grant date fair value of options granted under the Black-Scholes option pricing model, as well as a summary of the stock option activity under the Company's stock-based compensation plan for the years ended December 31, 2015 and 2014.
Income Taxes	Income Taxes Income taxes are recorded in accordance with ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided, if based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of December 31, 2015 and 2014, the Company does not have any significant uncertain tax positions.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive loss relates to unrealized investment losses on the Company's marketable securities for the years ended December 31, 2015 and 2014.
Basic and Diluted Net Loss Per Share of Common Stock	Basic and Diluted Net Loss Per Share of Common Stock Basic net loss per share of common stock is computed by dividing net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, excluding the dilutive effects of preferred stock, warrants to purchase preferred stock and stock options. Diluted net loss per share of common stock is computed by dividing the net loss attributable to common stockholders by the sum of the weighted-average number of shares of common stock outstanding during the period plus the potential dilutive effects of preferred stock and warrants to purchase preferred stock, and stock options outstanding during the period calculated in accordance with the treasury stock method, although these shares, options and warrants are excluded if their effect is anti-dilutive. Because the impact of these items is anti-dilutive during periods of net loss, there was no difference between basic and diluted net loss per share of common stock for the years ended December 31, 2015 and 2014.
Recent Accounting Pronouncements	Recent Accounting Pronouncements On April 7, 2015, the FASB issued Accounting Standards Update 2015-03, Simplifying the Presentation of Debt Issuance Costs ("ASU 2015-03"). ASU 2015-03 requires debt issuance costs to be presented in the balance sheets as a direct deduction from the associated debt liability. Although the standard is retrospectively effective for annual reporting periods beginning after December 15, 2015, early adoption is permitted for any annual reporting period or interim period for which the entity's financial statements have not yet been issued. The Company elected early adoption during the first quarter of 2015, which resulted in a balance sheet adjustment as of December 31, 2014 of $98,401 to other assets and loans payable, net. The Company's adoption of this standard had no impact on its results of operations or cash flows. See Note 6. In May 2014, the FASB issued Accounting Standards Update 2014-09 Revenue from Contracts with Customers ("ASU 2014-09"). ASU 2014-09 is a comprehensive new revenue recognition model requiring a company to recognize revenue to depict the transfer of goods or services to a customer in an amount reflecting the consideration it expects to receive in exchange for those goods or services. In July 2015, the FASB decided to defer the effective date of the standard from January 1, 2017, to January 1, 2018, with an option that permits companies to adopt the standard as early as the original effective date. Early application prior to the original effective date is not permitted. The standard permits the use of either the retrospective or cumulative effect transition method. We are evaluating the transition method we will elect. The adoption of this standard is not expected to have a material impact on the Company's financial statements.

Fair Value of Financial Instr22

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value of Financial Instruments
Schedule of cash and available-for-sale securities' adjusted cost, gross unrealized gains, gross unrealized losses and fair values by significant investment category	December 31, 2015 Adjusted Cost Unrealized Gains Unrealized Losses Fair Value Cash and Cash Equivalents Marketable Securities Cash $ $ — $ — $ $ $ — Level 1(1): Money market funds — — — U.S. Treasury securities ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 2(2): Repurchase agreements — — — U.S. government agency securities ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ) $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2014 Adjusted Cost Unrealized Gains Unrealized Losses Fair Value Cash and Cash Equivalents Marketable Securities Cash $ $ — $ — $ $ $ — Level 1(1): Money market funds — — — U.S. Treasury securities ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ ) $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The fair value of Level 1 securities is estimated based on quoted prices in active markets for identical assets or liabilities. (2) The fair value of Level 2 securities is estimated based on observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term on the assets or liabilities.
Schedule of changes in the fair value of the Company's warrant liability representing a recurring measurement classified within Level 3, wherein fair value is estimated using significant unobservable inputs	Warrant Liability Balance as of January 1, 2014 $ Amounts acquired or issued — Changes in estimated fair value ) Amounts reclassified to additional paid-in capital ) ​ ​ ​ ​ ​ Balance as of December 31, 2014 Amounts acquired or issued — Changes in estimated fair value ​ ​ ​ ​ ​ Balance as of December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of assumptions used for valuation of warrants	December 31, 2015 2014 Common stock warrant liability Common stock warrant liability Estimated remaining term 6.3 years 7.3 years Risk-free interest rate % % Volatility % % Dividend yield % % Fair value of underlying instrument* $ $ * Trevena, Inc. closing stock price.

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property and Equipment
Schedule of property and equipment	December 31, 2015 2014 Laboratory equipment $ $ Computers and software Office equipment and furniture Leasehold improvements Leased assets ​ ​ ​ ​ ​ ​ ​ ​ Total property and equipment Less accumulated depreciation and amortization ) ) ​ ​ ​ ​ ​ ​ ​ ​ Property and equipment, net $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Accrued Expenses and Other Cu24

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2015
Accrued Expenses and Other Current Liabilities
Schedule of accrued expenses and other current liabilities	December 31, 2015 2014 Compensation and benefits $ $ Clinical trial expenses Other research and development expenses — Other accrued expenses and other current liabilities ​ ​ ​ ​ ​ ​ ​ ​ Total accrued expenses and other current liabilities $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Loans Payable (Tables)

Loans Payable (Tables) - Term Loans A and B	12 Months Ended
	Dec. 31, 2015
Long Term Debt
Schedule of loans reflected on the balance sheet	December 31, 2015 Gross proceeds $ Debt discount ) Debt issuance costs ) ​ ​ ​ ​ ​ Carrying value $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of maturities of long term debt	Aggregate maturities of long term debt as of December 31, 2015 are as follows: 2016 — 2017 2018 2019 2020 ​ ​ ​ ​ ​ Debt Discount and deferred financing costs ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule of share-based compensation expense recognized	Year Ended December 31, 2015 2014 Research and development $ $ General and administrative ​ ​ ​ ​ ​ ​ ​ ​ Total stock-based compensation $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Summary of stock option activity	Options Outstanding Number of Shares Weighted- Average Exercise Price Weighted Average Remaining Contractual Term (in years) Balance, December 31, 2013 $ Granted Exercised ) Forfeitures ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2014 $ Granted Exercised ) Forfeitures ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Vested or expected to vest at December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Exercisable at December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of weighted-average assumptions:	Year Ended December 31, 2015 Year Ended December 31, 2014 Expected term of options (in years) Risk-free interest rate % % Expected volatility % % Dividend yield % %
Schedule of shares of common stock reserved/available	At December 31, 2015, the Company has reserved the following shares of common stock for issuance: Stock options outstanding Shares available for future grant under 2013 Plan Employee stock purchase plan Warrants outstanding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
2013 plan
Schedule of shares of common stock reserved/available	Available at December 31, 2014 Authorized Granted ) Forfeitures/Expirations ​ ​ ​ ​ ​ Available at December 31, 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies.
Schedule of future minimum lease payments, including termination fees, under non cancelable lease agreements	Future minimum lease payments, including termination fees, under noncancelable agreements as of December 31, 2015, are as follows: Operating Lease 2016 $ 2017 2018 2019 2020 and beyond ​ ​ ​ ​ ​ Total minimum lease payments $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Net Loss Per Common Share (Tabl

Net Loss Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2015
Net Loss Per Common Share
Schedule of computation of basic and diluted net loss per share	Year Ended December 31, 2015 2014 Basic and diluted net loss per common share calculation: Net loss $ ) $ ) Accretion of redeemable convertible preferred stock — ) ​ ​ ​ ​ ​ ​ ​ ​ Net loss attributable to common stockholders $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average common shares outstanding ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share of common stock—basic and diluted $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of outstanding securities excluded from the computation of diluted weighted shares outstanding as they would have been anti-dilutive	December 31, 2015 2014 Options outstanding Warrants ​ ​ ​ ​ ​ ​ ​ ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Comprehensive Loss (Tables)

Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2015
Comprehensive Loss
Schedule of accumulated other comprehensive income or loss	Balance, January 1, 2014 $ — Net unrealized loss arising during the period ​ ​ ​ ​ ​ Balance, December 31, 2014 $ Net unrealized loss arising during the period ​ ​ ​ ​ ​ Balance, December 31, 2015 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Taxes
Schedule of significant components of the Company's deferred tax assets	December 31, 2015 2014 Deferred tax assets: Net operating loss carryforwards $ $ Research and development credits Research and development expenses capitalized for tax purposes Deferred rent Depreciation Other temporary differences ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax assets Deferred tax liabilities: Prepaid expenses ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax assets Less valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax asset $ — $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of reconciliation of income tax expense computed at the statutory federal income tax rate to income taxes as reflected in the financial statements	December 31, 2015 2014 Percent of pre-tax income: U.S. federal statutory income tax rate % % Permanent Differences % )% State taxes, net of federal benefit % % Research and development credit % % Other % — Change in valuation allowance )% )% ​ ​ ​ ​ ​ ​ ​ ​ Effective income tax rate % % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Organization and Description 31

Organization and Description of the Business (Details)	12 Months Ended
	Dec. 31, 2015USD ($)item	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Organization and Description of the Business
Number of operating segments | item	1
Liquidity
Accumulated deficit	$ 182,497,965	$ 131,969,725
Net loss	(50,528,240)	(49,700,875)
Cash and cash equivalents	46,773,566	36,205,559	$ 37,965,198
Marketable securities	$ 125,864,447	$ 70,698,640

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2015USD ($)item$ / shares	Dec. 31, 2014USD ($)$ / shares
Property and Equipment
Impairment losses	$ 0
Investments
Minimum percentage value of RRAs collateralized by deposits in the form of Government Securities and Obligations	102.00%
Marketable Securities	$ 125,864,447	$ 70,698,640
Charges for other-than-temporary declines in fair value of short-term or long-term investments	0	0
Change in unrealized loss on marketable securities	(187,074)	$ (18,782)
Restricted Cash
Letters of credit	$ 112,000
Stock-Based Compensation
Number of stock-based compensation plans | item	1
Basic and diluted net loss per common share calculation:
Difference between basic and diluted net loss per share of Common Stock | $ / shares	$ 0	$ 0
Accounting pronouncements reclassifications
Loans payable, net	$ 18,185,898	$ 1,692,884
Accounting Standards Update ("ASU") 2015-03 - Simplifying the Presentation of Debt Issuance Costs | Early adoption adjustment amounts
Accounting pronouncements reclassifications
Other assets	(98,401)
Loans payable, net	(98,401)
Company Website
Intangible Asset
Intangible asset	15,000
Amortization expense on intangible assets	156
Amortization expected to recognize in 2016	1,875
Amortization expected to recognize in 2017	1,875
Amortization expected to recognize in 2018	1,875
Amortization expected to recognize in 2019	1,875
Amortization expected to recognize in 2020	1,875
Amortization expected to recognize in 2021	1,875
Amortization expected to recognize in 2022	1,875
Amortization expected to recognize in 2023	$ 1,875
Computer equipment
Property and Equipment
Estimated useful life	P3Y
Laboratory equipment, office equipment, furniture and software
Property and Equipment
Estimated useful life	P5Y

Fair Value of Financial Instr33

Fair Value of Financial Instruments - Hierarchy Table (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair value
Charges for other-than-temporary declines in fair value of investments	$ 0	$ 0
Available-for-sale investment securities with contractual maturity date of more than one but less than two years	22,500,000
Cash
Fair value
Adjusted Cost	20,672,737	7,141,548
Fair Value	20,672,737	7,141,548
Cash and Cash Equivalents | Cash
Fair value
Fair Value	20,672,737	7,141,548
Total
Fair value
Adjusted Cost	172,843,869	106,922,981
Unrealized Gains	361	258
Unrealized Losses	(206,217)	(19,040)
Fair Value	172,638,013	106,904,199
Total | Cash and Cash Equivalents
Fair value
Fair Value	46,773,566	36,205,559
Total | Marketable Securities.
Fair value
Fair Value	125,864,447	70,698,640
Level 1
Fair value
Adjusted Cost	16,121,691	99,781,433
Unrealized Gains	92	258
Unrealized Losses	(1,434)	(19,040)
Fair Value	16,120,349	99,762,651
Level 1 | Cash and Cash Equivalents
Fair value
Fair Value	4,100,829	29,064,011
Level 1 | Marketable Securities.
Fair value
Fair Value	12,019,520	70,698,640
Level 1 | Money market mutual funds
Fair value
Adjusted Cost	4,100,829	29,064,011
Fair Value	4,100,829	29,064,011
Level 1 | Money market mutual funds | Cash and Cash Equivalents
Fair value
Fair Value	4,100,829	29,064,011
Level 1 | U.S. Treasury securities
Fair value
Adjusted Cost	12,020,862	70,717,422
Unrealized Gains	92	258
Unrealized Losses	(1,434)	(19,040)
Fair Value	12,019,520	70,698,640
Level 1 | U.S. Treasury securities | Marketable Securities.
Fair value
Fair Value	12,019,520	70,698,640
Level 2
Fair value
Adjusted Cost	136,049,441
Unrealized Gains	269
Unrealized Losses	(204,783)
Fair Value	135,844,927
Level 2 | Cash and Cash Equivalents
Fair value
Fair Value	22,000,000
Level 2 | Marketable Securities.
Fair value
Fair Value	113,844,927
Level 2 | Repurchase agreements
Fair value
Adjusted Cost	22,000,000
Fair Value	22,000,000
Level 2 | Repurchase agreements | Cash and Cash Equivalents
Fair value
Fair Value	22,000,000
Level 2 | U.S. government agency securities
Fair value
Adjusted Cost	114,049,441
Unrealized Gains	269
Unrealized Losses	(204,783)
Fair Value	113,844,927
Level 2 | U.S. government agency securities | Marketable Securities.
Fair value
Fair Value	113,844,927
Level 3
Fair value
Transfers into Level 3	0	0
Transfers out of Level 3	$ 0	$ 0

Fair Value of Financial Instr34

Fair Value of Financial Instruments - Warrant Liability (Details) - Warrants	Dec. 31, 2015USD ($)shares
Fair value, warrant liability
Fair value of the warrants outstanding | $	$ 153,238
Common Stock | Maximum
Fair value, warrant liability
Number of shares called upon exercise of warrants (in shares) | shares	20,161

Fair Value of Financial Instr35

Fair Value of Financial Instruments - Summary of Changes in Warrant Liability (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Warrant Liability
Changes in estimated fair value	$ 70,387	$ (122,412)
Warrants | Warrant Liability
Warrant Liability
Balance at the beginning of the period	82,851	350,519
Changes in estimated fair value	70,387	(122,412)
Amounts reclassified to additional paid-in capital		(145,256)
Balance at the end of the period	$ 153,238	$ 82,851

Fair Value of Financial Instr36

Fair Value of Financial Instruments - Warrant Liability Assumptions (Details) - Warrants - Common Stock - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 23, 2015	Sep. 19, 2014
Lenders and Placement Agent
Warrants
Number of shares called upon exercise of warrants (in shares)			42,639	42,639
Level 3
Fair value assumptions
Estimated remaining term	6 years 3 months 18 days	7 years 3 months 18 days
Risk-free interest rate (as a percent)	2.00%	2.00%
Volatility (as a percent)	67.40%	71.80%
Dividend yield (as a percent)	0.00%	0.00%
Fair value of underlying instrument (in dollar per share)	$ 10.50	$ 5.98

Property and Equipment (Details

Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property and Equipment
Property and equipment, gross	$ 4,656,924	$ 4,442,338
Less accumulated depreciation and amortization	(3,960,644)	(3,889,044)
Property, plant and equipment, net, total	696,280	553,294
Depreciation and amortization expense	207,897	239,390
Laboratory equipment
Property and Equipment
Property and equipment, gross	1,796,355	1,616,420
Computers and software
Property and Equipment
Property and equipment, gross	503,462	554,658
Office equipment and furniture
Property and Equipment
Property and equipment, gross	281,350	270,845
Leasehold improvements
Property and Equipment
Property and equipment, gross	2,061,498	1,986,156
Leased Assets
Property and Equipment
Property and equipment, gross	$ 14,259	$ 14,259

Accrued Expenses and Other Cu38

Accrued Expenses and Other Current Liabilities (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Accrued Expenses and Other Current Liabilities
Compensation and benefits	$ 2,599,565	$ 1,628,102
Clinical trial expenses	401,029	846,199
Other research and development expenses		96,088
Other accrued expenses and other current liabilities	29,188	7,880
Total accrued expenses and other current liabilities	$ 3,029,782	$ 2,578,269

Loans Payable - Term Loans (Det

Loans Payable - Term Loans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2014
Long Term Debt
Interest rate (as a percent)	6.50%
Amortization of debt discount and issuance costs	$ 124,572	$ 25,417
Carrying value	18,185,898	1,692,884
Interest expense	334,365	70,650
Minimum net cash proceeds from strategic partnerships as a condition to extend the date for payments	50,000,000
Fees
Facility fee			$ 175,000
Debt Instrument Amendment Fee	20,000
Loan and security agreement
Long Term Debt
Face amount			35,000,000
Term Loan A
Long Term Debt
Face amount			2,000,000
Deferred financing fees			106,545
Debt discount			(225,988)
Term Loan B
Long Term Debt
Face amount	16,500,000
Deferred financing fees	87,500
Debt discount	(44,058)
Term Loan C
Long Term Debt
Face amount	16,500,000
Term Loans A and B
Long Term Debt
Gross proceeds	18,500,000
Debt discount	(168,501)
Debt issuance costs	(145,601)
Carrying value	18,185,898
Interest expense	$ 164,667	$ 36,833
Fees
Prepayment fee as a percent of total amount prepaid if prepayment occurs prior to the first anniversary of the funding	3.00%
Prepayment fee as a percent of total amount prepaid if prepayment occurs between the first and second anniversary of the funding	2.00%
Prepayment fee as a percent of total amount prepaid if prepayment occurs on or after the second anniversary of the funding	1.00%
Minimum
Fees
Final payment fee due upon that last payment date of the amounts borrowed under the agreement subject to adjustment (as a percent)	6.10%
Maximum
Fees
Final payment fee due upon that last payment date of the amounts borrowed under the agreement subject to adjustment (as a percent)	7.00%
Three Point
Fees
Facility fee			$ 65,000
Three Point | Term Loan B
Fees
Facility fee	$ 87,500
Three Point | Term Loan C
Fees
Additional fee if draws are made on term loans	$ 87,500
Warrants
Warrants
Exercise price (in dollars per share)	$ 10.6190		$ 5.8610
Warrants | Common Stock | Term Loan B
Warrants
Number of shares called upon exercise of warrants (in shares)	34,961
Warrants | Common Stock | Maximum
Warrants
Number of shares called upon exercise of warrants (in shares)	20,161
Warrants | Common Stock | Lenders and Placement Agent
Warrants
Number of shares called upon exercise of warrants (in shares)			7,678

Loans Payable - Maturities (Det

Loans Payable - Maturities (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Aggregate maturities of long term debt
Loans payable, net	$ 18,185,898	$ 1,692,884
Term Loans A and B
Aggregate maturities of long term debt
2,017	5,692,308
2,018	5,692,307
2,019	5,692,308
2,020	1,423,077
Loans payable, gross	18,500,000
Debt discount and deferred financing costs	(314,102)
Loans payable, net	$ 18,185,898

Stockholders' Equity - Equity O

Stockholders' Equity - Equity Offerings (Details) - USD ($)	Sep. 16, 2015	Jul. 07, 2015	May. 08, 2015	Dec. 10, 2014	Mar. 06, 2014	Feb. 05, 2014	Dec. 31, 2015	Dec. 31, 2014
Equity Offerings
Aggregate gross proceeds from shares sold							$ 90,306,634	$ 107,290,323
Proceeds from issuance of common stock, net							$ 90,310,634	$ 107,290,323
Common stock, shares authorized							100,000,000	100,000,000
Preferred Stock, shares authorized							5,000,000	5,000,000
Public Offering
Equity Offerings
Issuance of common stock in public offering (in shares)				11,250,000
Issuance of common stock underwriters allotment option (in shares)				1,598,000
Issuance of common stock (in shares)	7,475,000			12,848,000
Offering price (in dollars per share)	$ 9.75			$ 4
Aggregate gross proceeds from shares sold	$ 72,900,000			$ 51,400,000
Proceeds from issuance of common stock, net	68,300,000
Payment of underwriting discounts and commissions	4,400,000
Offering expenses	$ 200,000
At-the-market sales facility
Equity Offerings
Issuance of common stock (in shares)		1,000,000	2,700,000
Aggregate gross proceeds from shares sold		$ 6,000,000	$ 16,900,000
Proceeds from issuance of common stock, net		5,800,000	16,200,000
Payment of underwriting discounts and commissions		$ 200,000	$ 500,000
At-the-market sales facility | Weighted-average
Equity Offerings
Offering price (in dollars per share)		$ 6.0001	$ 6.2503
Initial public offering
Equity Offerings
Issuance of common stock underwriters allotment option (in shares)					270,449
Issuance of common stock (in shares)						9,250,000
Offering price (in dollars per share)					$ 7	$ 7
Aggregate gross proceeds from shares sold					$ 1,900,000	$ 64,800,000

Stockholders' Equity - Equity I

Stockholders' Equity - Equity Incentive Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Options outstanding
Equity Incentive Plans
Stock-based compensation	$ 3,426,730	$ 2,383,399
Options outstanding | Research and development
Equity Incentive Plans
Stock-based compensation	1,460,061	1,129,244
Options outstanding | General and administrative
Equity Incentive Plans
Stock-based compensation	$ 1,966,669	$ 1,254,155
2008 and 2013 Plans | Maximum
Equity Incentive Plans
Term of award	10 years
Vesting period	4 years

Stockholder's Equity - Options

Stockholder's Equity - Options Outstanding (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of Shares
Balance at the end of the period (in shares)	4,630,073
Options outstanding
Number of Shares
Balance at the beginning of the period (in shares)	3,574,450	2,795,746
Granted (in shares)	1,645,960	1,095,042
Exercised (in shares)	(384,033)	(186,687)
Forfeitures (in shares)	(206,304)	(129,651)
Balance at the end of the period (in shares)	4,630,073	3,574,450	2,795,746
Vested or expected to vest at the end of the period (in shares)	4,488,894
Exercisable at the end of the period (in shares)	1,941,347
Weighted-Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 3.75	$ 2.52
Granted (in dollars per share)	7.16	6.75
Exercised (in dollars per share)	2.36	0.60
Forfeitures/Expirations (in dollars per share)	6.04	7.20
Balance at the end of the period (in dollars per share)	4.98	$ 3.75	$ 2.52
Vested or expected to vest at the end of the period (in dollars per share)	4.91
Exercisable at the end of the period (in dollars per share)	$ 3.10
Weighted Average Remaining Contractual Term
Options Outstanding at the end of the period	7 years 10 months 13 days	8 years 22 days	8 years 5 months 12 days

Stockholder's Equity - Shares A

Stockholder's Equity - Shares Available for Future Issuance (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Weighted-average assumptions:
Estimated annual forfeiture rate (as a percent)	9.00%	7.00%
Shares Available for Future Grant
Balance at the end of the period (in shares)	959,354
Shares Reserved for Future Issuance
Stock options outstanding (in shares)			4,630,073
Shares available for future grant under 2013 Plan (in shares)	959,354		959,354
Employee stock purchase plan			225,806
Warrants outstanding (in shares)			62,800
Total shares of common stock reserved for issuance			5,878,033
2013 plan
Shares Available for Future Grant
Balance at the beginning of the period (in shares)	829,364
Authorized (in shares)			1,569,646
Granted (in shares)	(1,645,960)
Forfeitures/Expirations (in shares)	206,304
Balance at the end of the period (in shares)	959,354	829,364
Shares Reserved for Future Issuance
Shares available for future grant under 2013 Plan (in shares)	829,364	829,364	959,354	829,364
Options outstanding
Equity Incentive Plans
Intrinsic value of options exercisable			$ 14.4
Per share price of Company's closing stock price (in dollars per share)			$ 10.50
Weighted average exercise price (in dollars per share)			$ 3.10
Per-share weighted-average grant date fair value of options granted (in dollars per share)	$ 4.49	$ 4.43
Weighted-average assumptions:
Unrecognized compensation expense			$ 9
Weighted average remaining period for recognition of unrecognized compensation expense	2 years 9 months 4 days
Shares Reserved for Future Issuance
Stock options outstanding (in shares)			4,630,073	3,574,450	2,795,746
Options outstanding | Weighted-average
Weighted-average assumptions:
Expected term of options (in years)	6 years 2 months 12 days	5 years 9 months 18 days
Risk-free interest rate (as a percent)	1.70%	1.80%
Expected volatility (as a percent)	68.50%	75.90%
Dividend yield (as a percent)	0.00%	0.00%

Commitments and Contingencies -

Commitments and Contingencies - Licenses (Details) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2015USD ($)person	Dec. 31, 2015USD ($)	Dec. 31, 2014
Allergan
Collaboration Revenue.
Payment received to fund expansion of clinical trial	$ 10
Number of patients before expansion of the trial | person	500
Number of patients after expansion of the trial | person	620
Option agreement and a license agreement | Minimum
Collaboration Revenue.
Tiered royalties that could be received, as a percentage of net sales of licensed products		10.00%
Option agreement and a license agreement | Maximum
Collaboration Revenue.
Tiered royalties that could be received, as a percentage of net sales of licensed products			20.00%
Option agreement and a license agreement | Allergan
Collaboration Revenue.
Consideration received upon the grant of the option		$ 0
Aggregate potential consideration		365
Option exercise fee		$ 65
Term of royalty on sales from the first commercial sale of product		10 years

Commitments and Contingencies46

Commitments and Contingencies - Operating Leases (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies
Rent expense	$ 589,762	$ 489,810
Future minimum payments under operating leases
2,016	305,851
2,017	314,208
2,018	322,564
2,019	330,921
2020 and beyond	253,512
Total minimum lease payments	1,527,056
Office and laboratory space
Commitments and Contingencies
Termination payment if the Company opts to terminate the lease	150,000
Future minimum payments under operating leases
Deferred rent	$ 282,824	$ 320,244
Vivarium space
Commitments and Contingencies
Notice period	90 days

Revenue (Details)

Revenue (Details) - USD ($)	1 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2015
Revenue
Collaboration revenue		$ 6,250,000
Allergan
Revenue
Collaboration revenue		$ 6,300,000
Nonrefundable upfront fee	$ 10,000,000

Net Loss Per Common Share (Deta

Net Loss Per Common Share (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Outstanding securities excluded from computation of diluted weighted shares outstanding as they would have been anti dilutive:
Outstanding securities excluded from computation of diluted weighted shares outstanding (in shares)	4,692,873	3,604,708
Basic and diluted net loss per common share calculation:
Net loss	$ (50,528,240)	$ (49,700,875)
Accretion of redeemable convertible preferred stock		(28,521)
Net loss attributable to common stockholders	$ (50,528,240)	$ (49,729,396)
Weighted average common shares outstanding	43,794,276	24,655,603
Net loss per share of common stock-basic and diluted	$ (1.15)	$ (2.02)
Options outstanding
Outstanding securities excluded from computation of diluted weighted shares outstanding as they would have been anti dilutive:
Outstanding securities excluded from computation of diluted weighted shares outstanding (in shares)	4,630,073	3,574,450
Warrants
Outstanding securities excluded from computation of diluted weighted shares outstanding as they would have been anti dilutive:
Outstanding securities excluded from computation of diluted weighted shares outstanding (in shares)	62,800	30,258

Comprehensive Loss (Details)

Comprehensive Loss (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax.
Accumulated other comprehensive income (loss), net of tax, beginning balance	$ 18,782
Net unrealized gain arising during the period	187,074	$ 18,782
Accumulated other comprehensive income (loss), net of tax, ending balance	205,856	18,782
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Tax effect	$ 0	$ 0

Income Taxes - Deferred Taxes (

Income Taxes - Deferred Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income Taxes
Net loss before income taxes	$ 50,528,240	$ 49,700,875
Deferred tax assets:
Net operating loss carryforwards	11,649,441	9,245,934
Research and development credits	6,824,974	5,101,755
Research and development expenses capitalized for tax purposes	61,073,917	43,038,057
Deferred rent	103,454	129,998
Depreciation	552,235	476,799
Other temporary differences	653,078	458,413
Total deferred tax assets	80,857,099	58,450,956
Deferred tax liabilities:
Prepaid expenses	(81,706)	(90,385)
Total deferred tax liabilities	(81,706)	(90,385)
Net deferred tax assets	80,775,393	58,360,571
Less valuation allowance	(80,775,393)	(58,360,571)
Increase in valuation allowance	$ 22,400,000	$ 22,100,000

Income Taxes - Effective Tax Ra

Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating loss carryforwards
Interest and penalties related to uncertain tax positions	$ 0	$ 0
Research and development credit retroactively reinstated	$ 2,400,000	$ 1,800,000
Percent of pre-tax income:
U.S. federal statutory income tax rate (as a percent)	34.00%	34.00%
Permanent Differences (as a percent)	0.10%	(0.60%)
State taxes, net of federal benefit (as a percent)	6.60%	6.50%
Research and development credit (as a percent)	3.90%	3.90%
Other	0.30%
Change in valuation allowance (as a percent)	(44.90%)	(43.80%)
Effective income tax rate (as a percent)	0.00%	0.00%
Research and development.
Operating loss carryforwards
Uncertain tax position recognized	$ 0	$ 0
U.S. federal
Operating loss carryforwards
Net operating loss carryforwards	28,700,000	22,800,000
U.S. federal | Research and development.
Operating loss carryforwards
Tax credit carryforwards	6,800,000	4,700,000
U.S. state
Operating loss carryforwards
Net operating loss carryforwards	$ 28,700,000	$ 22,800,000

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined contribution plan
Employer matching contribution for employee's contributions of the first 3% of eligible compensation (as a percent)	100.00%
Percentage of eligible compensation, matched 100% by employer	3.00%
Employer matching contribution for employee's contributions of the next 2% of eligible compensation (as a percent)	50.00%
Percentage of eligible compensation, matched 50% by employer	2.00%
Company's matching contributions to the plan	$ 319,282	$ 204,537

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	Jul. 07, 2015	May. 08, 2015	Feb. 29, 2016	Dec. 31, 2015	Dec. 31, 2014
Subsequent Event.
Proceeds from issuance of common stock, net				$ 90,310,634	$ 107,290,323
At-the-market sales facility
Subsequent Event.
Issuance of common stock (in shares)	1,000,000	2,700,000
Proceeds from issuance of common stock, net	$ 5,800,000	$ 16,200,000
Subsequent event | At-the-market sales facility
Subsequent Event.
Issuance of common stock (in shares)			1,350,755
Proceeds from issuance of common stock, net			$ 11,800,000
Weighted-average | At-the-market sales facility
Subsequent Event.
Offering price (in dollars per share)	$ 6.0001	$ 6.2503
Weighted-average | Subsequent event | At-the-market sales facility
Subsequent Event.
Offering price (in dollars per share)			$ 9