Evoke Pharma (EVOK) 10-K 10 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	Feb. 29, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	EVOK
Entity Registrant Name	Evoke Pharma Inc
Entity Central Index Key	1,403,708
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		7,201,774
Entity Public Float		$ 14

Balance Sheets

Balance Sheets - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 8,691,155	$ 14,155,809
Prepaid expenses	833,276	931,461
Other current assets		137,812
Total current assets	9,524,431	15,225,082
Other assets	7,997	7,997
Total assets	9,532,428	15,233,079
Current Liabilities:
Accounts payable and accrued expenses	927,606	1,011,629
Accrued compensation	760,782	697,245
Other current liabilities		12,313
Current portion of long-term debt	146,052	126,806
Total current liabilities	1,834,440	1,847,993
Long-term debt, net of current portion	4,233,059	4,196,422
Total liabilities	$ 6,067,499	$ 6,044,415
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value; authorized shares — 5,000,000 at December 31, 2015 and 2014; issued and outstanding shares — 0 at December 31, 2015 and 2014
Common stock, $0.0001 par value; authorized shares — 50,000,000 at December 31, 2015 and 2014; issued and outstanding shares — 7,201,774 and 6,112,091 at December 31, 2015 and 2014, respectively	$ 720	$ 611
Additional paid-in capital	51,524,821	45,127,202
Accumulated deficit	(48,060,612)	(35,939,149)
Total stockholders' equity	3,464,929	9,188,664
Total liabilities and stockholders' equity	$ 9,532,428	$ 15,233,079

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	7,201,774	6,112,091
Common stock, shares outstanding	7,201,774	6,112,091

Statements of Operations

Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating expenses:
Research and development	$ 8,154,144	$ 9,991,855
General and administrative	3,664,159	3,158,179
Total operating expenses	11,818,303	13,150,034
Loss from operations	(11,818,303)	(13,150,034)
Other expense	(303,160)	(97,647)
Net loss	$ (12,121,463)	$ (13,247,681)
Net loss per common share, basic and diluted	$ (1.87)	$ (2.20)
Weighted-average shares used to compute basic and diluted net loss per share	6,485,794	6,032,560

Statements of Stockholders' Equ

Statements of Stockholders' Equity - USD ($)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2013	$ 21,183,261	$ 610	$ 43,874,119	$ (22,691,468)
Beginning Balance, Shares at Dec. 31, 2013		6,096,752
Stock-based compensation expense	1,102,087		1,102,087
Issuance of common stock upon exercise of warrant, Shares		2,795
Issuance of common stock upon exercise of stock option	1,522		1,522
Issuance of common stock upon exercise of stock option, Shares		5,250
Issuance of common stock from employee stock purchase plan	$ 41,353	$ 1	41,352
Issuance of common stock from employee stock purchase plan, Shares	7,294	7,294
Fair market value of issued warrant	$ 108,122		108,122
Net loss	(13,247,681)			(13,247,681)
Ending Balance at Dec. 31, 2014	$ 9,188,664	$ 611	45,127,202	(35,939,149)
Ending Balance, Shares at Dec. 31, 2014	6,112,091	6,112,091
Stock-based compensation expense	$ 1,504,356		1,504,356
Issuance of common stock from At-The-Market offering, net	4,723,572	$ 105	4,723,467
Issuance of common stock from At-The-Market offering, shares net		1,048,507
Issuance of common stock from employee stock purchase plan	$ 169,800	$ 4	169,796
Issuance of common stock from employee stock purchase plan, Shares	41,176	41,176
Net loss	$ (12,121,463)			(12,121,463)
Ending Balance at Dec. 31, 2015	$ 3,464,929	$ 720	$ 51,524,821	$ (48,060,612)
Ending Balance, Shares at Dec. 31, 2015	7,201,774	7,201,774

Statements of Cash Flows

Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (12,121,463)	$ (13,247,681)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,504,356	1,102,087
Non-cash interest	55,883	59,982
Deferred rent expense	(12,313)	5,483
Change in operating assets and liabilities:
Prepaid expenses and other assets	98,185	(287,503)
Accounts payable and accrued expenses	(20,486)	866,560
Net cash used in operating activities	(10,495,838)	(11,501,072)
Financing activities
Proceeds from bank line of credit		4,500,000
Payment on bank line of credit		(3,000,000)
Costs paid in connection with loan origination		(82,685)
Proceeds from issuance of common stock, net	5,031,184	42,875
Net cash provided by financing activities	5,031,184	1,460,190
Net increase (decrease) in cash and cash equivalents	(5,464,654)	(10,040,882)
Cash and cash equivalents at beginning of period	14,155,809	24,196,691
Cash and cash equivalents at end of period	8,691,155	14,155,809
Supplemental disclosure of cash flow information
Cash paid for interest	230,313	$ 58,790
Non-cash financing activities
Deferred financing costs paid in prior year	$ 137,812

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Evoke Pharma, Inc. (the “Company”) was incorporated in the state of Delaware on January 29, 2007. The Company is a publicly-held specialty pharmaceutical company focused primarily on the development of drugs to treat gastroenterological disorders and disease. Since its inception, the Company has devoted substantially all of its efforts to product development, raising capital and building infrastructure, and has not realized revenues from its planned principal operations. The Company does not anticipate realizing revenues for the foreseeable future. The Company’s activities are subject to significant risks and uncertainties, including funding its operations beyond the completion of its ongoing Phase 3 clinical trial for EVK-001. The Company’s recurring losses from operations raise substantial doubt about its ability to continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Company has experienced significant losses since its inception, including net losses of $12.1 million and $13.2 million for the years ended December 31, 2015 and 2014, respectively. As of December 31, 2015, the Company had an accumulated deficit of $48.1 million, approximately $8.7 million in cash and cash equivalents, and $4.5 million in borrowings under its bank credit facility. Substantially all the Company’s net losses have resulted from costs incurred in connection with its research and development programs and its general and administrative costs to support operations. The Company’s net losses may fluctuate significantly from quarter to quarter and year to year. In its report on the Company’s financial statements for the year ended December 31, 2015, our independent registered public accounting firm included an explanatory paragraph expressing substantial doubt regarding our ability to continue as a going concern. The Company expects to continue to incur net losses for at least the next several years. The Company will need to raise additional debt or equity financing to fund any additional development requirements requested by the U.S. Food and Drug Administration (“FDA”), as well as for new drug application (“NDA”) preparation and pre-commercial activities, including marketing and manufacturing of EVK-001. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, and/or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations, financial condition and future prospects.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”). The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates. Segment Reporting 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 in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment operating in the United States. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less from the date of purchase to be cash equivalents. Cash and cash equivalents include cash in readily available checking and savings accounts. Fair Value of Financial Instruments The carrying amounts of all financial instruments, including accounts payable and accrued expenses, and employee-related liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. Based on the borrowing rates currently available to the Company for loans with similar terms, the Company believes that the fair value of long-term debt approximates its carrying value. Concentrations of Risk Financial instruments that potentially subject the Company to significant credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in a federally insured financial institution in excess of federally insured limits. The Company has established guidelines designed to maintain safety and liquidity, has not experienced any losses in such accounts and believes the exposure to significant risk to the cash balance is minimal. The Company also relies on clinical research organizations (“CROs”) to manage and recruit subjects for its clinical trials. If these CROs are unable to continue managing the clinical trials, or are unable to recruit the sufficient number of subjects, the delays could adversely affect the completion of the trials and the timing of the filing of the Company’s NDA with the FDA. In addition, the Company relies on third-party manufacturers for the production of its drug candidate. If the third-party manufacturers are unable to continue manufacturing the Company’s drug candidate, or if the Company loses one of its sole source suppliers used in its manufacturing processes, the Company may not be able to meet clinical trial supply demand for its product candidate and the development of the product candidate could be materially and adversely affected. Deferred Offering Costs Deferred offering costs of approximately $138,000, which primarily consist of legal, accounting and filing fees relating to the Company’s Form S-3 filed in November 2014, have been capitalized and are included in other current assets as of December 31, 2014 on the accompanying balance sheet. The deferred offering costs were offset against the proceeds from the January 2015 offering described in Note 6. Stock-Based Compensation Stock-based compensation expense for stock option grants and employee stock purchase plan shares is recorded at the estimated fair value of the award as of the grant date and is recognized as expense on a straight-line basis over the employee’s requisite service period. The estimation of stock option and employee stock purchase plan fair value requires management to make estimates and judgments about, among other things, employee exercise behavior, forfeiture rates and volatility of the Company’s common stock. The judgments directly affect the amount of compensation expense that will be recognized. Prior to the Company’s initial public offering (“IPO”), the Company granted stock options to purchase common stock to employees with exercise prices equal to the value of the underlying stock, as determined by the board of directors on the date the equity award was granted. The board of directors determined the fair value of the underlying common stock by considering a number of factors, including historical and projected financial results, the risks the Company faced at the time, the preferences of the Company’s preferred stockholders and the lack of liquidity of the Company’s common stock. Subsequent to the IPO, the exercise price of the stock options granted to employees and members of the board of directors of the Company was determined by the Company’s closing market price on the date the stock options were granted. T he risk-free interest rate assumption was based on the yield of an applicable rate for U.S. Treasury instruments with maturities similar to those of the expected term of the award being valued. The weighted average expected term of options and employee stock purchases was calculated using the simplified method as prescribed by accounting guidance for stock-based compensation. This decision was based on the lack of relevant historical data due to the Company’s limited historical experience. In addition, due to the Company’s limited historical data, the estimated volatility was calculated based upon the Company’s historical volatility, supplemented with historical volatility of comparable companies in the biotechnology industry whose share prices are publicly available for a sufficient period of time. The assumed dividend yield was based on the Company never paying cash dividends and having no expectation of paying cash dividends in the foreseeable future. Research and Development Expenses Research and development costs are expensed as incurred and primarily include compensation and related benefits, stock-based compensation expense, costs paid to third-party contractors to perform research, conduct clinical trials and develop drug materials and delivery devices. The Company expenses costs relating to the purchase and production of pre-approval inventories as research and development expense in the period incurred until FDA approval is received. The Company bases its expense accruals related to clinical studies on estimates of the services received and efforts expended pursuant to contracts with multiple research institutions and CROs that conduct and manage clinical studies on its behalf. The financial terms of these agreements vary from contract to contract and may result in uneven payment flows. Payments under some of these contracts depend on factors, such as the successful enrollment of subjects, site initiation and the completion of clinical study milestones. Service providers typically invoice the Company monthly in arrears for services performed. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the Company does not identify costs that have begun to be incurred, or if the Company underestimates or overestimates the level of services performed or the costs of these services, actual expenses could differ materially from estimates. To date, the Company has not experienced significant changes in estimates of accrued research and development expenses after a reporting period. However, due to the nature of estimates, no assurance can be made that changes to the estimates will not be made in the future as the Company becomes aware of additional information about the status or conduct of clinical studies and other research activities. The Company does not own or operate manufacturing facilities for the production of EVK-001, nor does it plan to develop its own manufacturing operations in the foreseeable future. The Company currently depends on third-party contract manufacturers for all of its required raw materials, drug substance and finished product for its preclinical research and clinical trials. The Company does not have any current contractual relationships for the manufacture of commercial supplies of EVK-001. If EVK-001 is approved by any regulatory agency, the Company intends to enter into agreements with third-party contract manufacturers for the commercial production at that time. The Company currently utilizes a third-party consultant, which it engages on an as-needed, hourly basis, to manage its manufacturing contractors. Income Taxes The Company accounts for income taxes in accordance with ASC 740, Income Taxes The Company’s policy related to accounting for uncertainty in income taxes prescribes a recognition threshold and measurement attributed criteria for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for common stock equivalents and adjusted for the weighted-average number of common shares outstanding that are subject to repurchase. The Company has excluded 45,000 and 70,625 weighted-average shares subject to repurchase from the weighted-average number of common shares outstanding for the years ended December 31, 2015 and 2014, respectively. Diluted net loss per share is calculated by dividing the net loss by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. In addition to the shares subject to repurchase, dilutive common stock equivalents are comprised of warrants for the purchase of common stock, options outstanding under the Company’s equity incentive plans and potential shares to be purchased under the Company’s employee stock purchase plan. For the periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. The following table sets forth the outstanding potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to do so would be anti-dilutive: Year Ended December 31, 2015 2014 Common stock subject to repurchase 45,000 70,625 Warrants to purchase common stock 118,881 118,881 Common stock options 1,037,500 683,500 Employee stock purchase plan 22,818 12,627 Total excluded securities 1,224,199 885,633 Recent Accounting Pronouncements In August 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-15 (Subtopic 205-40), Presentation of Financial Statements Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. Contingencies. In April 2015, the FASB issued ASU 2015-03, Interest – Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In November 2015, the FASB issued ASU No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. In February 2016, the FASB issued ASU No. 2016-02, Leases

Debt

Debt	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt	3. Debt In June 2012, the Company entered into a $3 million loan and security agreement with Silicon Valley Bank (“SVB”), collateralized by the Company’s personal property. The agreement also contained non-financial covenants. By January 2013, the Company had been advanced the entire $3 million. Interest on advances under the agreement was at a fixed interest rate equal to 4.50%. Advances under the loan and security agreement had an interest-only period through December 31, 2013, and had a 24-month payback period that commenced in January 2014. On May 23, 2014, the Company repaid the outstanding principal and accrued interest of approximately $2.4 million to SVB. In addition, the Company expensed approximately $38,000 of unamortized debt discount costs upon the repayment of the loan. With such payoff, the SVB loan agreement and the documents entered into in connection therewith were deemed to be terminated. SVB’s security interest in substantially all of the Company’s assets was also terminated. On May 28, 2014, the Company entered into a $4.5 million loan and security agreement (the “credit facility”) with Square 1 Bank, a division of Pacific Western Bank (“Square 1”), pursuant to which Square 1 agreed to make term loans available to the Company for general corporate and working capital purposes and for capital expenditures. In December 2014, the Company drew down the entire $4.5 million. The credit facility bears interest at a fixed annual rate of 5.50%. As a result of an amendment to the credit facility effected on October 5, 2015, the interest-only payment period was extended through November 28, 2016. The outstanding principal balance plus interest will begin amortizing at the end of the interest-only period, with monthly payments of principal and interest being made by the Company to Square 1 in consecutive monthly installments following November 28, 2016 until the credit facility matures on November 28, 2018. At the Company’s option, it may prepay the outstanding principal balance of the credit facility before November 28, 2018 without penalty or premium. The credit facility includes affirmative and negative covenants applicable to us and any subsidiaries we create in the future. The affirmative covenants include, among others, covenants requiring us to maintain our legal existence and governmental approvals, deliver certain financial reports, maintain insurance coverage and meet certain covenants with respect to enrollment and results of our EVK-001 Phase 3 trial. In September 2015, we announced that we had met a patient enrollment covenant requiring enrollment of 75% of the projected total Phase 3 trial enrollment. Prior to receiving positive results from the Phase 3 trial, we must either maintain a ratio of our cash at Square 1 to our cash burn over the preceding month of at least 4.00 to 1.00, or we must deliver evidence of a forthcoming financing or strategic partnership arrangement to Square 1, in each case in an amount satisfactory to Square 1. After we receive positive results from the Phase 3 trial, if at all (which we must achieve on or prior to September 30, 2016), we must either maintain a ratio of our cash at Square 1 to our cash burn over the preceding month of at least 3.00 to 1.00, or we must deliver evidence of a forthcoming financing or strategic partnership arrangement to Square 1, in each case in an amount satisfactory to Square 1. The negative covenants include, among others, restrictions on our transferring collateral, incurring additional indebtedness, engaging in mergers or acquisitions, paying dividends or making other distributions, making investments, creating liens and selling assets, in each case subject to certain exceptions. The credit facility also includes events of default, the occurrence and continuation of which provide Square 1 with the right to exercise remedies against the Company and the collateral securing the term loans under the credit facility, including foreclosure against the Company’s properties securing the credit facilities, including its cash. These events of default include, among other things, the Company’s failure to pay any amounts due under the credit facility, a breach of covenants under the credit facility, the Company’s insolvency, a material adverse change, the occurrence of any default under certain other indebtedness in an amount greater than $400,000 and a final judgment against the Company in an amount greater than $400,000. In connection with the funding of the term loan, the Company issued to Square 1 a warrant to purchase 22,881 shares of the Company’s common stock at an exercise price of $5.90 per share, the closing price of the Company’s common stock on the day of funding of the credit facility. The warrant expires on December 31, 2024. If the warrant has not been exercised prior to its expiration date, it will be deemed to automatically convert by “cashless” conversion. In the event that the Company is acquired, the warrant will be exercisable or deemed automatically converted, which shall be determined based upon whether the Company’s successor assumes the obligations of the warrant. The estimated fair value of the warrant issued to Square 1 was determined on the date of issuance using the Black-Scholes option-pricing valuation model with the following assumptions: Risk free interest rate 2.17% Expected warrant term 10 Years Expected volatility of common stock 77.19% Expected dividend yield 0.00% The value determined for the warrant of $108,122 has been recorded as a debt discount, as well as to stockholders’ equity. The debt discount is being amortized to interest expense over the remaining term of the credit facility. The Company incurred $82,685 of loan origination costs related to this credit facility. Such costs are being amortized to interest expense over the remaining term of the credit facility. Future maturities of long-term debt and interest payments under the credit facility as of December 31, 2015 are set forth below: 2016 $ 457,687 2017 2,432,904 2018 2,119,935 Total minimum payments 5,010,526 Less amounts representing interest (510,526 ) Gross balance of outstanding debt 4,500,000 Less debt discount (1) (73,978 ) Less origination costs (46,911 ) Total carrying value 4,379,111 Less current portion (146,052 ) Total carrying value, long-term portion $ 4,233,059 (1) Represents the initial fair value of the detachable warrants to purchase common stock issued in connection with the term debt, net of amortization. Total interest incurred under the loan and security agreements for the years ended December 31, 2015 and 2014 (excluding amortization of debt discount and loan origination costs) was $250,938 and $47,165, respectively.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Commitments	4. Commitments In November 2013, the Company entered into an operating lease for office space in Solana Beach, California. The lease commenced on December 1, 2013 and was amended in October 2015 to extend the expiration date to December 31, 2016. Although rent payments did not commence until December 2013, the Company took possession of the facility in November 2013 to move into the facility. The lease contains annual rent increases and the Company received lease incentives in the form of rent abatements and a moving allowance. Rent expense for 2015 and 2014 was $81,381 and $81,086, respectively. The Company also pays pass through costs and utility costs, which are expensed as incurred. As of December 31, 2015, the Company has future minimum lease payments under its operating lease in 2016 of approximately $113,000.

Technology Acquisition Agreemen

Technology Acquisition Agreement	12 Months Ended
	Dec. 31, 2015
Technology Acquisition Agreement [Abstract]
Technology Acquisition Agreement	5. Technology Acquisition Agreement In June 2007, the Company acquired all worldwide rights, data, patents and other related assets associated with EVK-001 from Questcor Pharmaceuticals, Inc. (“Questcor”) pursuant to an Asset Purchase Agreement. The Company paid Questcor $650,000 in the form of an upfront payment and $500,000 in May 2014 as a milestone payment based upon the initiation of the first patient dosing in the Company’s Phase 3 clinical trial for EVK-001. In August 2014, Mallinckrodt, plc, (“Mallinckrodt”) acquired Questcor. As a result of that acquisition, Questcor transferred its rights included in the Asset Purchase Agreement with the Company to Mallinckrodt. In addition to the payments made to Questcor, the Company may also be required to make additional milestone payments to Mallinckrodt totaling up to $51.5 million. These milestones include up to $4.5 million in payments if EVK-001 achieves the following development targets: — $1.5 million upon the FDA’s acceptance for review of an NDA for EVK-001; and — $3 million upon the FDA’s approval of EVK-001. The remaining $47 million in milestone payments depend on EVK-001’s commercial success and will only apply if EVK-001 receives regulatory approval. In addition, the Company will be required to pay to Mallinckrodt a low single digit royalty on net sales of EVK-001. The Company’s obligation to pay such royalties will terminate upon the expiration of the last patent right covering EVK-001, which is expected to occur in 2030.

Preferred Stock, Common Stock a

Preferred Stock, Common Stock and Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Preferred Stock, Common Stock and Stockholders' Equity	6. Preferred Stock, Common Stock and Stockholders’ Equity Preferred Stock Under the Company’s amended and restated certificate of incorporation, the Company is authorized to issue 5,000,000 shares of preferred stock with a $0.0001 par value. No shares of preferred stock were outstanding as of December 31, 2015 or 2014. Common Stock As of December 31, 2015, there were 7,201,774 shares of common stock outstanding. Each share of common stock is entitled to one vote. The holders of the common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors of the Company. To date, no dividends have been declared. On November 13, 2014, the Company entered into an At Market Sales Agreement (“Sales Agreement”) with MLV & Co. LLC (“MLV”), pursuant to which the Company may sell from time to time, at its option, up to an aggregate of $6.6 million worth of shares of common stock through MLV as sales agent. During September 2015, FBR & Co. (“FBR”), acquired MLV and assumed its rights and obligations under the Sales Agreement. The sales of shares of the Company’s common stock made through this equity program are made in “at-the-market” offerings as defined in Rule 415 of the Securities Act of 1933, as amended. During the year ended December 31, 2015, the Company sold 1,048,507 shares of common stock at a weighted average price per share of $4.78 pursuant to the Sales Agreement and received proceeds of approximately $4.9 million, net of commissions and fees. The Company incurred approximately $138,000 of legal, accounting and filing fees related to its Registration Statement on Form S-3 filed in November 2014. Such costs were capitalized and included in other current assets at December 31, 2014, and were reclassified to additional paid-in capital during the first quarter of 2015 as a further offset to the net proceeds. The Company intends to use the net proceeds to continue to fund its ongoing Phase 3 clinical trial and for general corporate purposes. Future sales will depend on a variety of factors including, but not limited to, market conditions, the trading price of the Company’s common stock and the Company’s capital needs. Although sales of the Company’s common stock have taken place pursuant to the Sales Agreement, there can be no assurance that FBR will be successful in consummating future sales based on prevailing market conditions or in the quantities or at the prices that the Company deems appropriate. Under current SEC regulations, at any time during which the aggregate market value of the Company’s common stock held by non-affiliates, or public float, is less than $75 million, the amount the Company can raise through primary public offerings of securities in any twelve-month period using shelf registration statements, including sales under the Sales Agreement, is limited to an aggregate of one-third of the Company’s public float. As of February 29, 2016, the Company’s public float was 4.1 million shares, the value of which was $14.6 million based upon the closing price of the Company’s common stock of $3.57 on February 22, 2016. The value of one-third of the Company’s public float calculated on the same basis was $4.8 million. As of February 29, 2016, the Company was unable to sell any further shares of common stock pursuant to the Sales Agreement due to current capacity restrictions. In addition, the Company will not be able to make future sales of common stock pursuant to the Sales Agreement unless certain conditions are met, which include the accuracy of representations and warranties made to FBR under the Sales Agreement. Furthermore, FBR is permitted to terminate the Sales Agreement in its sole discretion upon ten days’ notice, or at any time in certain circumstances, including the occurrence of an event that would be reasonably likely to have a material adverse effect on the Company’s assets, business, operations, earnings, properties, condition (financial or otherwise), prospects, stockholders’ equity or results of operations. The Company has no obligation to sell the remaining shares available for sale pursuant to the Sales Agreement. As a result of payroll withholdings from the Company’s employees of approximately $170,000, the Company also sold 41,176 shares of common stock through its Employee Stock Purchase Plan (“ESPP”) during the year ended December 31, 2015. Warrants The Company has issued warrants to purchase common stock to banks that have loaned funds to the Company, as well as to representatives of the underwriters of the Company’s initial public offering and certain of its affiliates. A summary of the Company’s warrant activity is as follows: Weighted Weighted Average Average Remaining Exercise Contractual Shares Price Term (Years) Outstanding at December 31, 2014 118,881 $ 16.73 5.35 Issued — — — Exercised — — — Expired/Forfeited — — — Outstanding at December 31, 2015 118,881 $ 16.73 4.35 Stock Options The Company adopted the 2007 Equity Incentive Plan (the “2007 Plan”) in May 2007 under which 450,000 shares of common stock were reserved for issuance to employees, nonemployee directors and consultants of the Company. As of December 31, 2015, no options were available for future grant under this plan. In August 2013, the Company adopted the 2013 Equity Incentive Award Plan (the “2013 Plan”) as a successor to the 2007 Plan. Under the 2013 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units and other awards to individuals who are then employees, officers, non-employee directors or consultants of the Company. A total of 510,000 shares of common stock were initially reserved for issuance under the 2013 Plan. In addition, the number of shares of common stock available for issuance under the 2013 Plan will be annually increased on the first day of each fiscal year during the term of the 2013 Plan, beginning with the 2014 fiscal year, by an amount equal to the least of: (i) 300,000 shares; (ii) four percent of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (iii) such other amount as the Company’s board of directors may determine. As a result of such calculation, since the 2013 Plan originated, the Company has increased the number shares reserved for issuance under the 2013 Plan by 488,354 shares. As of December 31, 2015, 78,854 options remain available for future grant under the 2013 Plan. On January 1, 2016, the Company further increased the number of shares reserved for issuance under the 2013 Plan by 288,071 shares, making 366,925 options available for future grant under the 2013 Plan. Options granted under the 2007 Plan and 2013 Plan have ten year terms from the date of grant and generally vest over a one to four year period. The Company granted options to purchase 354,000 and 64,000 shares of common stock in 2015 and 2014, respectively. The exercise price of all options granted during the years ended December 31, 2015 and 2014 was equal to the market value per share of the Company’s common stock on the date of grant. A summary of the Company’s stock option activity under the 2007 Plan and 2013 Plan is as follows: Weighted Weighted Average Average Remaining Exercise Contractual Aggregate Shares Price Term (Years) Intrinsic Outstanding at December 31, 2014 683,500 $ 7.67 8.45 $ 649,000 Granted 354,000 $ 6.25 9.20 — Exercised — — — — Expired/Forfeited — — — — Outstanding at December 31, 2015 1,037,500 $ 7.19 8.04 $ 342,200 Vested and expected to vest at December 31, 2015 1,037,500 $ 7.19 8.04 $ 342,200 Exercisable at December 31, 2015 530,079 $ 6.80 7.50 $ 342,200 The intrinsic values above represent the aggregate value of the total pre-tax intrinsic value based upon a common stock price of $3.30 and $5.90 at December 31, 2015 and 2014, respectively, and the contractual exercise price. The 2007 Plan permits the early exercise of options, but the Company has the option to repurchase any unvested shares at the original purchase price (the exercise price paid by the purchaser) upon any voluntary or involuntary termination. The shares of common stock issued from the exercise of stock options are restricted and vest over time or on the achievement of certain milestones. Any unvested shares immediately vest in the event of termination for reasons other than cause, and vesting accelerates in the event of a merger, sale, or other change in control of the Company. Of the total 332,000 stock options exercised, 287,000 were vested as of December 31, 2015 and 2014. The remaining 45,000 exercised stock options vest upon the submission of the NDA for EVK-001. The total intrinsic value of the stock option exercised based upon a common stock of $6.73 on the date of exercise was $33,810 for the year ended December 31, 2014. There were no options exercised in 2015. The Company had the following nonvested options under the 2007 Plan and 2013 Plan: Shares Weighted Average Grant Date Fair Value Per Share Nonvested at December 31, 2014 424,419 $ 9.02 Granted 354,000 $ 4.03 Vested (270,998 ) $ 8.07 Expired/Forfeited — — Nonvested at December 31, 2015 507,421 $ 7.60 Stock-Based Compensation Stock-based compensation expense includes charges related to stock option grants and employee stock purchases under the Company’s ESPP. The Company measures stock-based compensation expense based on the grant-date fair value of any awards granted to its employees. Such expense is recognized over the period of time that employees provide service and earn rights to the awards. The estimated fair value of each option award granted was determined on the date of grant using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for options grants during the two years ended December 31, 2015: Year Ended December 31, 2015 2014 Risk free interest rate 1.50% - 1.87% 1.66% - 1.77% Expected option term 5.5 - 6.0 years 5.5 - 6.0 years Expected volatility of common stock 71.99% - 76.74% 71.06% - 73.21% Expected dividend yield 0.0% 0.0% The weighted average grant date fair value per share of employee stock options granted during the years ended December 31, 2015 and 2014, was $4.03 and $4.76, respectively. In February 2016, the Company effected a one-time option exchange, wherein employees were offered the opportunity to exchange certain outstanding stock options for the grant of a lesser number of replacement stock options. The participants received three new stock options for every four stock options tendered for exchange. As a result, 703,500 stock options were exchanged for 527,624 replacement stock options. The 175,876 stock options that were not reissued may be granted in the future. The replacement stock options have a three-year vesting schedule and an exercise price of $3.04 per share, which was the closing price of the Company’s common stock on the date of the option exchange. All other terms of the replacement stock options remain the same as the original stock options that were exchanged. As a result of this transaction, the Company will recognize an incremental stock-based compensation expense of approximately $4,700 at the time of the transaction and an additional approximately $141,000 of stock-based compensation expense over the three-year vesting term of the exchanged options. Employee Stock Purchase Plan On June 13, 2013, the Company’s board of directors adopted the ESPP, and the Company’s stockholders approved the ESPP on August 29, 2013. The ESPP became effective on the day prior to the effectiveness of the IPO. The ESPP permits participants to purchase the Company’s common stock at 85% of the fair market value through payroll deductions of up to 20% of their eligible compensation. A total of 30,000 shares of common stock were initially reserved for issuance under the ESPP. In addition, the number of shares of common stock available for issuance under the ESPP is annually increased on the first day of each fiscal year during the term of the ESPP by an amount equal to the lesser of: (i) 30,000 shares; (ii) one percent of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (iii) such other amount as the Company’s board of directors may determine. As a result, the Company increased the number shares reserved for issuance under the ESPP by 30,000 shares on each of January 1, 2015 and 2014. During 2015 and 2014, 41,176 and 7,294 shares of common stock, respectively, were issued under the ESPP. As of December 31, 2015, 41,530 shares remain available for future issuance under the ESPP. On January 1, 2016, the Company further increased the number of shares reserved for future issuance under the ESPP by 30,000 shares, making 71,530 shares available for future issuance under the ESPP after that increase. The estimated fair value of the shares to be acquired under the ESPP was determined on the initiation date of each six month purchase period using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for ESPP shares to be purchased during the year ended December 31, 2015 and 2014: Year Ended December 31, 2015 2014 Risk free interest rate 0.08% - 0.26% 0.05% - 0.08% Expected term 6 months 6 months Expected volatility of common stock 62.91% - 69.64% 69.32% - 73.21% Expected dividend yield 0.0% 0.0% The Company recognized non-cash stock-based compensation expense to employees and directors in its research and development and its general and administrative functions as follows: Year Ended December 31, 2015 2014 Research and development $ 579,078 $ 410,150 General and administrative 925,278 691,937 Total stock-based compensation expense $ 1,504,356 $ 1,102,087 As of December 31, 2015, there was approximately $2.3 million of unrecognized compensation costs related to outstanding employee and board of director options, which is expected to be recognized over a weighted average period of 1.13 years. Common Stock Reserved for Future Issuance Common stock reserved for future issuance consists of the following at December 31, 2015 and 2014: December 31, 2015 2014 Stock options issued and outstanding 1,037,500 683,500 Authorized for future option grants 78,854 188,370 Warrants to purchase common stock 118,881 118,881 Authorized for employee stock purchase plan 41,530 52,706 Total common stock reserved for future issuance 1,276,765 1,043,457

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2015
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plan	7. Employee Benefit Plan The Company has established a defined contribution 401(k) plan (the “Plan”) for all employees who are at least 21 years of age. Employees are eligible to participate in the Plan beginning on the date of employment. Under the terms of the Plan, employees may make voluntary contributions as a percentage of compensation. The Company’s contributions to the Plan are discretionary, and no contributions have been made by the Company to date. For the years ended December 31, 2015 and 2014, the Company adopted Safe Harbor 401(k) provisions. In order to maintain the Plan’s compliance with Internal Revenue Service regulations, approximately $20,000 was contributed to the accounts of certain employees for the year ended December 31, 2014 and approximately $6,700 will be contributed to the accounts of certain employees for the year ended December 31, 2015.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes The Company accounts for uncertain tax positions in accordance with Accounting Standards Codification Topic 740, Income Taxes (“ASC 740”). The application of income tax law and regulations is inherently complex. Interpretations and guidance surrounding income tax laws and regulations change over time. As such, changes in the Company’s subjective assumptions and judgments can materially affect amounts recognized in its financial statements. The Company’s policy is to recognize interest and/or penalties related to income tax matters in income tax expense. The Company had no accrual for interest and penalties on the balance sheets at December 31, 2015 and 2014. The Company is subject to taxation in the United States and state jurisdictions, and the Company’s tax years beginning 2007 to date are subject to examination by taxing authorities. The Company does not foresee material changes to its gross uncertain income tax position liability within the next twelve months. A reconciliation of the federal statutory income tax rate and the effective income tax rate is as follows for the years ended December 31, 2015 and 2014: December 31, 2015 2014 (%) (%) Federal statutory rate 34.0 34.0 Change in valuation allowance (1.6 ) (1.6 ) State income taxes, net of federal effect 5.8 5.8 Research and development credits 4.1 5.0 Removal of net operating loss and other credits (39.2 ) (41.2 ) Stock compensation and other permanent items (3.1 ) (2.0 ) Effective income tax rate 0.0 0.0 Pursuant to Internal Revenue Code (“IRC”) Sections 382 and 383, annual use of the Company’s net operating loss and research and development credit carryforwards may be limited in the event a cumulative change in ownership of more than 50% occurs within a three-year period. The Company has not completed an IRC Section 382/383 analysis regarding the limitation of net operating loss and research and development credit carryforwards. Until this analysis has been completed, the Company has removed the deferred tax assets for net operating losses of approximately $17.4 million and a research and development credit of approximately $2.1 million generated through December 31, 2015 from its deferred tax asset schedule, and has recorded a corresponding decrease to its valuation allowance. When this analysis is finalized, the Company plans to update its unrecognized tax benefits accordingly. The Company does not expect this analysis to be completed within the next twelve months and, as a result, the Company does not expect that the unrecognized tax benefits will change within twelve months of this reporting date. Due to the existence of the valuation allowance, future changes in the Company’s unrecognized tax benefits will not impact the Company’s effective tax rate. Significant components of the Company’s deferred tax assets at December 31, 2015 and 2014 are as follows: December 31, 2015 2014 Acquired technology $ 276,000 $ 317,000 Stock compensation expense 430,000 223,000 Accruals and other 124,000 105,000 Total deferred tax assets 830,000 645,000 Less valuation allowance (830,000 ) (645,000 ) Net deferred tax assets $ — $ — At December 31, 2015, the Company has federal and California net operating loss carryforwards of approximately $43.9 million and $42.9 million, respectively. The federal and California loss carryforwards begin to expire in 2027 and 2017, respectively, unless previously utilized. The Company also has federal and California research tax credit carryforwards of approximately $1.5 million and $1.0 million, respectively. The federal research credit carryforwards will begin expiring in 2027 unless previously utilized. The California research credit will carry forward indefinitely.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions	9. Related Party Transactions An officer of the Company serves on the executive management team of a CRO that provided clinical trial services to the Company. For the years ended December 31, 2015 and 2014, the Company incurred an aggregate of approximately $218,000, and $255,000, respectively, in fees for these services. As of December 31, 2015, accounts payable did not include any related party transactions. As of December 31, 2014, accounts payable included approximately $22,000 of related party transactions.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	10. Subsequent Events For the purposes of the financial statements as of December 31, 2015 and the year then ended, the Company has evaluated subsequent events through the date the audited annual financial statements were issued. The Company has concluded that no subsequent event has occurred other than what has been disclosed.

Summarized Quarterly Data

Summarized Quarterly Data	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Summarized Quarterly Data	11. Summarized Quarterly Data (Unaudited) The following financial information reflects all adjustments, which include only normal recurring adjustments, which are, in the opinion of management, necessary for a fair statement of the financial results of the interim periods. Summarized quarterly data for the years ended December 31, 2015 and 2014 are as follows: For the Quarters Ended March 31, June 30, September 30, December 31, 2015 Research and development expense $ 2,419,961 $ 2,188,138 $ 1,837,743 $ 1,708,302 General and administrative expense $ 1,025,261 $ 976,418 $ 819,703 $ 842,777 Net loss $ (3,520,748 ) $ (3,241,163 ) $ (2,735,400 ) $ (2,624,152 ) Net loss per common share, basic and diluted (1) $ (0.58 ) $ (0.52 ) $ (0.42 ) $ (0.37 ) Weighted average shares outstanding, basic and diluted 6,103,783 6,212,803 6,494,845 7,123,163 2014 Research and development expense $ 1,852,116 $ 2,874,977 $ 3,088,373 $ 2,176,388 General and administrative expense $ 1,070,479 $ 616,888 $ 732,800 $ 738,012 Net loss $ (2,955,484 ) $ (3,547,040 ) $ (3,825,354 ) $ (2,919,803 ) Net loss per common share, basic and diluted (1) $ (0.49 ) $ (0.59 ) $ (0.63 ) $ (0.48 ) Weighted average shares outstanding, basic and diluted 6,002,936 6,027,672 6,054,250 6,065,841 (1) Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.

Summary of Significant Accoun18

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”). The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates.
Segment Reporting	Segment Reporting 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 in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment operating in the United States.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less from the date of purchase to be cash equivalents. Cash and cash equivalents include cash in readily available checking and savings accounts.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of all financial instruments, including accounts payable and accrued expenses, and employee-related liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. Based on the borrowing rates currently available to the Company for loans with similar terms, the Company believes that the fair value of long-term debt approximates its carrying value.
Concentrations of Risk	Concentrations of Risk Financial instruments that potentially subject the Company to significant credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in a federally insured financial institution in excess of federally insured limits. The Company has established guidelines designed to maintain safety and liquidity, has not experienced any losses in such accounts and believes the exposure to significant risk to the cash balance is minimal. The Company also relies on clinical research organizations (“CROs”) to manage and recruit subjects for its clinical trials. If these CROs are unable to continue managing the clinical trials, or are unable to recruit the sufficient number of subjects, the delays could adversely affect the completion of the trials and the timing of the filing of the Company’s NDA with the FDA. In addition, the Company relies on third-party manufacturers for the production of its drug candidate. If the third-party manufacturers are unable to continue manufacturing the Company’s drug candidate, or if the Company loses one of its sole source suppliers used in its manufacturing processes, the Company may not be able to meet clinical trial supply demand for its product candidate and the development of the product candidate could be materially and adversely affected.
Deferred Offering Costs	Deferred Offering Costs Deferred offering costs of approximately $138,000, which primarily consist of legal, accounting and filing fees relating to the Company’s Form S-3 filed in November 2014, have been capitalized and are included in other current assets as of December 31, 2014 on the accompanying balance sheet. The deferred offering costs were offset against the proceeds from the January 2015 offering described in Note 6.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense for stock option grants and employee stock purchase plan shares is recorded at the estimated fair value of the award as of the grant date and is recognized as expense on a straight-line basis over the employee’s requisite service period. The estimation of stock option and employee stock purchase plan fair value requires management to make estimates and judgments about, among other things, employee exercise behavior, forfeiture rates and volatility of the Company’s common stock. The judgments directly affect the amount of compensation expense that will be recognized. Prior to the Company’s initial public offering (“IPO”), the Company granted stock options to purchase common stock to employees with exercise prices equal to the value of the underlying stock, as determined by the board of directors on the date the equity award was granted. The board of directors determined the fair value of the underlying common stock by considering a number of factors, including historical and projected financial results, the risks the Company faced at the time, the preferences of the Company’s preferred stockholders and the lack of liquidity of the Company’s common stock. Subsequent to the IPO, the exercise price of the stock options granted to employees and members of the board of directors of the Company was determined by the Company’s closing market price on the date the stock options were granted. T he risk-free interest rate assumption was based on the yield of an applicable rate for U.S. Treasury instruments with maturities similar to those of the expected term of the award being valued. The weighted average expected term of options and employee stock purchases was calculated using the simplified method as prescribed by accounting guidance for stock-based compensation. This decision was based on the lack of relevant historical data due to the Company’s limited historical experience. In addition, due to the Company’s limited historical data, the estimated volatility was calculated based upon the Company’s historical volatility, supplemented with historical volatility of comparable companies in the biotechnology industry whose share prices are publicly available for a sufficient period of time. The assumed dividend yield was based on the Company never paying cash dividends and having no expectation of paying cash dividends in the foreseeable future.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred and primarily include compensation and related benefits, stock-based compensation expense, costs paid to third-party contractors to perform research, conduct clinical trials and develop drug materials and delivery devices. The Company expenses costs relating to the purchase and production of pre-approval inventories as research and development expense in the period incurred until FDA approval is received. The Company bases its expense accruals related to clinical studies on estimates of the services received and efforts expended pursuant to contracts with multiple research institutions and CROs that conduct and manage clinical studies on its behalf. The financial terms of these agreements vary from contract to contract and may result in uneven payment flows. Payments under some of these contracts depend on factors, such as the successful enrollment of subjects, site initiation and the completion of clinical study milestones. Service providers typically invoice the Company monthly in arrears for services performed. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the Company does not identify costs that have begun to be incurred, or if the Company underestimates or overestimates the level of services performed or the costs of these services, actual expenses could differ materially from estimates. To date, the Company has not experienced significant changes in estimates of accrued research and development expenses after a reporting period. However, due to the nature of estimates, no assurance can be made that changes to the estimates will not be made in the future as the Company becomes aware of additional information about the status or conduct of clinical studies and other research activities. The Company does not own or operate manufacturing facilities for the production of EVK-001, nor does it plan to develop its own manufacturing operations in the foreseeable future. The Company currently depends on third-party contract manufacturers for all of its required raw materials, drug substance and finished product for its preclinical research and clinical trials. The Company does not have any current contractual relationships for the manufacture of commercial supplies of EVK-001. If EVK-001 is approved by any regulatory agency, the Company intends to enter into agreements with third-party contract manufacturers for the commercial production at that time. The Company currently utilizes a third-party consultant, which it engages on an as-needed, hourly basis, to manage its manufacturing contractors.
Income Taxes	Income Taxes The Company accounts for income taxes in accordance with ASC 740, Income Taxes The Company’s policy related to accounting for uncertainty in income taxes prescribes a recognition threshold and measurement attributed criteria for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for common stock equivalents and adjusted for the weighted-average number of common shares outstanding that are subject to repurchase. The Company has excluded 45,000 and 70,625 weighted-average shares subject to repurchase from the weighted-average number of common shares outstanding for the years ended December 31, 2015 and 2014, respectively. Diluted net loss per share is calculated by dividing the net loss by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. In addition to the shares subject to repurchase, dilutive common stock equivalents are comprised of warrants for the purchase of common stock, options outstanding under the Company’s equity incentive plans and potential shares to be purchased under the Company’s employee stock purchase plan. For the periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. The following table sets forth the outstanding potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to do so would be anti-dilutive: Year Ended December 31, 2015 2014 Common stock subject to repurchase 45,000 70,625 Warrants to purchase common stock 118,881 118,881 Common stock options 1,037,500 683,500 Employee stock purchase plan 22,818 12,627 Total excluded securities 1,224,199 885,633
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-15 (Subtopic 205-40), Presentation of Financial Statements Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. Contingencies. In April 2015, the FASB issued ASU 2015-03, Interest – Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In November 2015, the FASB issued ASU No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. In February 2016, the FASB issued ASU No. 2016-02, Leases

Summary of Significant Accoun19

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Outstanding Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	The following table sets forth the outstanding potentially dilutive securities that have been excluded from the calculation of diluted net loss per share because to do so would be anti-dilutive: Year Ended December 31, 2015 2014 Common stock subject to repurchase 45,000 70,625 Warrants to purchase common stock 118,881 118,881 Common stock options 1,037,500 683,500 Employee stock purchase plan 22,818 12,627 Total excluded securities 1,224,199 885,633

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Assumptions Used in Estimation of Initial Fair Value of Warrants	The estimated fair value of the warrant issued to Square 1 was determined on the date of issuance using the Black-Scholes option-pricing valuation model with the following assumptions: Risk free interest rate 2.17% Expected warrant term 10 Years Expected volatility of common stock 77.19% Expected dividend yield 0.00%
Schedule of Maturities of Long-Term Debt	Future maturities of long-term debt and interest payments under the credit facility as of December 31, 2015 are set forth below: 2016 $ 457,687 2017 2,432,904 2018 2,119,935 Total minimum payments 5,010,526 Less amounts representing interest (510,526 ) Gross balance of outstanding debt 4,500,000 Less debt discount (1) (73,978 ) Less origination costs (46,911 ) Total carrying value 4,379,111 Less current portion (146,052 ) Total carrying value, long-term portion $ 4,233,059 1. Represents the initial fair value of the detachable warrants to purchase common stock issued in connection with the term debt, net of amortization.

Preferred Stock, Common Stock21

Preferred Stock, Common Stock and Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Summary of Warrants Activity	A summary of the Company’s warrant activity is as follows: Weighted Weighted Average Average Remaining Exercise Contractual Shares Price Term (Years) Outstanding at December 31, 2014 118,881 $ 16.73 5.35 Issued — — — Exercised — — — Expired/Forfeited — — — Outstanding at December 31, 2015 118,881 $ 16.73 4.35
Summary of Stock Option Activity	A summary of the Company’s stock option activity under the 2007 Plan and 2013 Plan is as follows: Weighted Weighted Average Average Remaining Exercise Contractual Aggregate Shares Price Term (Years) Intrinsic Outstanding at December 31, 2014 683,500 $ 7.67 8.45 $ 649,000 Granted 354,000 $ 6.25 9.20 — Exercised — — — — Expired/Forfeited — — — — Outstanding at December 31, 2015 1,037,500 $ 7.19 8.04 $ 342,200 Vested and expected to vest at December 31, 2015 1,037,500 $ 7.19 8.04 $ 342,200 Exercisable at December 31, 2015 530,079 $ 6.80 7.50 $ 342,200
Summary of Nonvested Options Activity	The Company had the following nonvested options under the 2007 Plan and 2013 Plan: Shares Weighted Average Grant Date Fair Value Per Share Nonvested at December 31, 2014 424,419 $ 9.02 Granted 354,000 $ 4.03 Vested (270,998 ) $ 8.07 Expired/Forfeited — — Nonvested at December 31, 2015 507,421 $ 7.60
Summary of Estimated Fair Value of Stock Option Award	The estimated fair value of each option award granted was determined on the date of grant using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for options grants during the two years ended December 31, 2015: Year Ended December 31, 2015 2014 Risk free interest rate 1.50% - 1.87% 1.66% - 1.77% Expected option term 5.5 - 6.0 years 5.5 - 6.0 years Expected volatility of common stock 71.99% - 76.74% 71.06% - 73.21% Expected dividend yield 0.0% 0.0%
Summary of Estimated Fair Value of Employee Stock Purchase Plan Award	The estimated fair value of the shares to be acquired under the ESPP was determined on the initiation date of each six month purchase period using the Black-Scholes option-pricing valuation model with the following weighted-average assumptions for ESPP shares to be purchased during the year ended December 31, 2015 and 2014: Year Ended December 31, 2015 2014 Risk free interest rate 0.08% - 0.26% 0.05% - 0.08% Expected term 6 months 6 months Expected volatility of common stock 62.91% - 69.64% 69.32% - 73.21% Expected dividend yield 0.0% 0.0%
Summary of Recognized Non-Cash Stock-Based Compensation Expense	The Company recognized non-cash stock-based compensation expense to employees and directors in its research and development and its general and administrative functions as follows: Year Ended December 31, 2015 2014 Research and development $ 579,078 $ 410,150 General and administrative 925,278 691,937 Total stock-based compensation expense $ 1,504,356 $ 1,102,087
Summary of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance consists of the following at December 31, 2015 and 2014: December 31, 2015 2014 Stock options issued and outstanding 1,037,500 683,500 Authorized for future option grants 78,854 188,370 Warrants to purchase common stock 118,881 118,881 Authorized for employee stock purchase plan 41,530 52,706 Total common stock reserved for future issuance 1,276,765 1,043,457

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Reconciliation of Federal Statutory Income Tax Rate and Effective Income Tax Rate	A reconciliation of the federal statutory income tax rate and the effective income tax rate is as follows for the years ended December 31, 2015 and 2014: December 31, 2015 2014 (%) (%) Federal statutory rate 34.0 34.0 Change in valuation allowance (1.6 ) (1.6 ) State income taxes, net of federal effect 5.8 5.8 Research and development credits 4.1 5.0 Removal of net operating loss and other credits (39.2 ) (41.2 ) Stock compensation and other permanent items (3.1 ) (2.0 ) Effective income tax rate 0.0 0.0
Summary of Significant Components of Deferred Tax Assets	Significant components of the Company’s deferred tax assets at December 31, 2015 and 2014 are as follows: December 31, 2015 2014 Acquired technology $ 276,000 $ 317,000 Stock compensation expense 430,000 223,000 Accruals and other 124,000 105,000 Total deferred tax assets 830,000 645,000 Less valuation allowance (830,000 ) (645,000 ) Net deferred tax assets $ — $ —

Summarized Quarterly Data (Tabl

Summarized Quarterly Data (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Summarized Quarterly Data	Summarized quarterly data for the years ended December 31, 2015 and 2014 are as follows For the Quarters Ended March 31, June 30, September 30, December 31, 2015 Research and development expense $ 2,419,961 $ 2,188,138 $ 1,837,743 $ 1,708,302 General and administrative expense $ 1,025,261 $ 976,418 $ 819,703 $ 842,777 Net loss $ (3,520,748 ) $ (3,241,163 ) $ (2,735,400 ) $ (2,624,152 ) Net loss per common share, basic and diluted (1) $ (0.58 ) $ (0.52 ) $ (0.42 ) $ (0.37 ) Weighted average shares outstanding, basic and diluted 6,103,783 6,212,803 6,494,845 7,123,163 2014 Research and development expense $ 1,852,116 $ 2,874,977 $ 3,088,373 $ 2,176,388 General and administrative expense $ 1,070,479 $ 616,888 $ 732,800 $ 738,012 Net loss $ (2,955,484 ) $ (3,547,040 ) $ (3,825,354 ) $ (2,919,803 ) Net loss per common share, basic and diluted (1) $ (0.49 ) $ (0.59 ) $ (0.63 ) $ (0.48 ) Weighted average shares outstanding, basic and diluted 6,002,936 6,027,672 6,054,250 6,065,841 (1) Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.

Organization and Basis of Pre24

Organization and Basis of Presentation - Additional Information (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Date of incorporation									Jan. 29, 2007
Net loss	$ (2,624,152)	$ (2,735,400)	$ (3,241,163)	$ (3,520,748)	$ (2,919,803)	$ (3,825,354)	$ (3,547,040)	$ (2,955,484)	$ (12,121,463)	$ (13,247,681)
Accumulated deficit	(48,060,612)				(35,939,149)				(48,060,612)	(35,939,149)
Cash and cash equivalents	8,691,155				14,155,809				8,691,155	14,155,809	$ 24,196,691
Square 1 Bank [Member] | Loan and security agreement [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Borrowings under bank credit facility	$ 4,500,000				$ 4,500,000				$ 4,500,000	$ 4,500,000

Summary of Significant Accoun25

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015USD ($)Segmentshares	Dec. 31, 2014USD ($)shares
Significant Accounting Policies [Line Items]
Number of operating segment | Segment	1
Deferred offering costs	$ 138,000
Weighted-average shares subject to repurchase excluded from the weighted-average number of common shares outstanding | shares	45,000	70,625
Current portion of long-term debt	$ 146,052	$ 126,806
Long-term debt, net of current portion	$ 4,233,059	4,196,422
Imputation of Interest [Member]
Significant Accounting Policies [Line Items]
Current portion of long-term debt		23,624
Long-term debt, net of current portion		$ 45,026

Summary of Significant Accoun26

Summary of Significant Accounting Policies - Summary of Outstanding Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of diluted net loss per share	1,224,199	885,633
Common stock subject to repurchase [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of diluted net loss per share	45,000	70,625
Warrants to purchase common stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of diluted net loss per share	118,881	118,881
Common stock options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of diluted net loss per share	1,037,500	683,500
Employee stock purchase plan [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the calculation of diluted net loss per share	22,818	12,627

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($)		Oct. 05, 2015	May. 28, 2014	May. 23, 2014	Sep. 30, 2015	Jun. 30, 2012	Dec. 31, 2015	Dec. 31, 2014	Jan. 31, 2013
Debt Instrument [Line Items]
Repayment of principal and accrued interest								$ 3,000,000
Debt Instrument, Unamortized Discount	[1]						$ 73,978
Warrant exercise price per share							$ 16.73	$ 16.73
Line of credit facility, loan origination cost								$ 82,685
Loan and security agreement [Member]
Debt Instrument [Line Items]
Loan and security agreement, interest incurred							$ 250,938	47,165
Silicon Valley Bank [Member] | Loan and security agreement [Member]
Debt Instrument [Line Items]
Loan and security agreement, maximum credit						$ 3,000,000
Loan and security agreement, amount drawn									$ 3,000,000
Loan and security agreement, interest rate						4.50%
Loan and security agreement, payback period						24 months
Repayment of principal and accrued interest				$ 2,400,000
Debt Instrument, Unamortized Discount				$ 38,000
Square 1 Bank [Member]
Debt Instrument [Line Items]
Patient enrollment covenant					75.00%
Square 1 Bank [Member] | Maximum [Member]
Debt Instrument [Line Items]
Cash burn under credit facility							4.00%
Square 1 Bank [Member] | Maximum [Member] | Upon Receive Positive Results From Phase 3 Trial [Member]
Debt Instrument [Line Items]
Cash burn under credit facility							3.00%
Square 1 Bank [Member] | Minimum [Member]
Debt Instrument [Line Items]
Cash burn under credit facility							1.00%
Square 1 Bank [Member] | Minimum [Member] | Upon Receive Positive Results From Phase 3 Trial [Member]
Debt Instrument [Line Items]
Cash burn under credit facility							1.00%
Square 1 Bank [Member] | Loan and security agreement [Member]
Debt Instrument [Line Items]
Loan and security agreement, amount drawn							$ 4,500,000	$ 4,500,000
Loan and security agreement, available credit			$ 4,500,000
Fixed interest rate								5.50%
Debt instrument interest payment, extended date		Nov. 28, 2016
Credit facility maturity date							Nov. 28, 2018
Loan and security agreement, amount of other indebtedness			400,000				$ 400,000
Warrants exercisable, stock issued							22,881
Warrant exercise price per share							$ 5.90
Warrant expiration date							Dec. 31, 2024
Line of credit facility, loan origination cost			$ 82,685
Square 1 Bank [Member] | Loan and security agreement [Member] | Warrant [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount							$ 108,122
Warrant value recorded in equity							$ 108,122
[1]	Represents the initial fair value of the detachable warrants to purchase common stock issued in connection with the term debt, net of amortization.

Debt - Assumptions Used in Esti

Debt - Assumptions Used in Estimation of Initial Fair Value of Warrants (Detail) - Square 1 Bank [Member]	12 Months Ended
	Dec. 31, 2015
Debt Instrument [Line Items]
Risk free interest rate	2.17%
Expected warrant term	10 years
Expected volatility of common stock	77.19%
Expected dividend yield	0.00%

Debt - Schedule of Maturities o

Debt - Schedule of Maturities of Long-Term Debt (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
2,016		$ 457,687
2,017		2,432,904
2,018		2,119,935
Total minimum payments		5,010,526
Less amounts representing interest		(510,526)
Gross balance of outstanding debt		4,500,000
Less debt discount	[1]	(73,978)
Less origination costs		(46,911)
Total carrying value		4,379,111
Less current portion		(146,052)	$ (126,806)
Long-term debt, net of current portion		$ 4,233,059	$ 4,196,422
[1]	Represents the initial fair value of the detachable warrants to purchase common stock issued in connection with the term debt, net of amortization.

Commitments - Additional Inform

Commitments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Lease commencement date	Dec. 1, 2013
Lease amendment date	2015-10
Lease expiry date	Dec. 31, 2016
Rent expense	$ 81,381	$ 81,086
Future minimum operating lease payment due in 2016	$ 113,000

Technology Acquisition Agreem31

Technology Acquisition Agreement - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	May. 31, 2014	Jun. 30, 2007	Dec. 31, 2015
Technology Acquisition Agreement [Line Items]
Payment expensed as in-process research and development		$ 650,000
Mallinckrodt Plc [Member] | Patented Technology [Member]
Technology Acquisition Agreement [Line Items]
Expected expiration of patent right			2,030
Mallinckrodt Plc [Member] | Rights and Patents Acquired from Questcor Pharmaceuticals Inc [Member] | Maximum [Member]
Technology Acquisition Agreement [Line Items]
Milestone payments contingent amount			$ 51,500,000
Development Target One [Member] | Rights and Patents Acquired from Questcor Pharmaceuticals Inc [Member]
Technology Acquisition Agreement [Line Items]
Milestone payment	$ 500,000
Development targets description			Upon the initiation of the first patient dosing in the Company's Phase 3 clinical trial for EVK-001
Development Target Two And Three [Member] | Mallinckrodt Plc [Member] | Maximum [Member]
Technology Acquisition Agreement [Line Items]
Milestone payments contingent amount			$ 4,500,000
Development Target Two [Member] | Mallinckrodt Plc [Member]
Technology Acquisition Agreement [Line Items]
Development targets description			Upon the FDA’s acceptance for review of an NDA for EVK-001
Milestone payments contingent amount			$ 1,500,000
Development Target Three [Member] | Mallinckrodt Plc [Member]
Technology Acquisition Agreement [Line Items]
Development targets description			Upon the FDA's approval of EVK-001
Milestone payments contingent amount			$ 3,000,000
Development Target Four [Member] | Mallinckrodt Plc [Member] | Patented Technology [Member]
Technology Acquisition Agreement [Line Items]
Development targets description			Depend on EVK-001's commercial success and will only apply if EVK-001 receives regulatory approval. In addition, the Company will be required to pay to Mallinckrodt a low single digit royalty on net sales of EVK-001.
Milestone payments contingent amount			$ 47,000,000

Preferred Stock, Common Stock32

Preferred Stock, Common Stock and Stockholders' Equity - Preferred Stock - Additional Information (Detail) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares outstanding	0	0

Preferred Stock, Common Stock33

Preferred Stock, Common Stock and Stockholders' Equity - Common Stock - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Feb. 29, 2016	Feb. 22, 2016	Nov. 13, 2014
Sale Of Stock [Line Items]
Common stock, shares outstanding	7,201,774	6,112,091
Shareholders voting power description	Each share of common stock is entitled to one vote. The holders of the common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors of the Company.
Dividends declared on common stock	$ 0
Common stock, shares issued	7,201,774	6,112,091
Proceeds from issuance of common stock, net	$ 5,031,184	$ 42,875
Legal, Accounting and Filing Fees	138,000
Payroll withholdings from employees	$ 170,000
Common stock for Employee Stock Purchase Plan	41,176	7,294
Sales Agreement with MLV & Co. LLC [Member]
Sale Of Stock [Line Items]
Common stock, value of shares issuable					$ 6,600,000
Common stock, shares issued	1,048,507
Common stock , weighted average price per share	$ 4.78
Proceeds from issuance of common stock, net	$ 4,900,000
Aggregate market value of entity common stock held by non affiliates	$ 75,000,000
Sales Agreement with MLV & Co. LLC [Member] | Subsequent Event [Member]
Sale Of Stock [Line Items]
Entity public float, common stock shares			4,100,000
Entity public float			$ 14,600,000
Common stock, closing price				$ 3.57
One third value of entity public float			$ 4,800,000

Preferred Stock, Common Stock34

Preferred Stock, Common Stock and Stockholders' Equity - Summary of Warrants Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Shares, Outstanding beginning balance	118,881
Shares, Outstanding ending balance	118,881	118,881
Weighted Average Exercise Price, Outstanding beginning balance	$ 16.73
Weighted Average Exercise Price, Outstanding ending balance	$ 16.73	$ 16.73
Weighted Average Remaining Contractual Term (Years), Outstanding	4 years 4 months 6 days	5 years 4 months 6 days

Preferred Stock, Common Stock35

Preferred Stock, Common Stock and Stockholders' Equity - Stock Options - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Feb. 29, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)Option$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Jan. 01, 2016shares	Aug. 31, 2013shares	May. 31, 2007shares
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance		1,276,765	1,043,457
Options available for future grant		78,854	188,370
Number of stock options granted		354,000
Intrinsic value, common stock price | $ / shares		$ 3.30	$ 5.90
Stock options vested		270,998
Number of stock options unvested		507,421	424,419
Total intrinsic value of stock options exercised | $			$ 33,810
Intrinsic value of stock option exercised, common stock price | $ / shares			$ 6.73
Weighted Average Grant Date Fair Value Per Share, Granted | $ / shares		$ 4.03	$ 4.76
Number of stock options exchanged, outstanding		1,037,500	683,500
Replacement stock options exercise price | $ / shares		$ 7.19	$ 7.67
Unrecognized compensation costs | $		$ 2,300,000
Weighted average period		1 year 1 month 17 days
Subsequent Event [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock options exchanged, outstanding	703,500
Options Granted [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, weighted average term		10 years
Number of stock options granted		354,000	64,000
Options Granted [Member] | Minimum [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting period		1 year
Options Granted [Member] | Maximum [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting period		4 years
2007 Equity Incentive Plan [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance		0				450,000
Issuance of common stock upon exercise of stock option, Shares		332,000
Stock options vested		287,000	287,000
Number of stock options unvested		45,000
Number of options exercised | Option		0
2013 Equity Incentive Award Plan [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance					510,000
Additional common stock reserved for issuance		488,354
Shares of common stock available for issuance description		In addition, the number of shares of common stock available for issuance under the 2013 Plan will be annually increased on the first day of each fiscal year during the term of the 2013 Plan, beginning with the 2014 fiscal year, by an amount equal to the least of: (i) 300,000 shares; (ii) four percent of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (iii) such other amount as the Company’s board of directors may determine.
Options available for future grant		78,854
2013 Equity Incentive Award Plan [Member] | Subsequent Event [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance				288,071
Options available for future grant				366,925
2013 Equity Incentive Award Plan [Member] | Annual Increase in Shares [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance		300,000
Reserve percentage for issuance of shares		4.00%
One-Time Option Exchange Program [Member] | Subsequent Event [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options available for future grant	175,876
Options granted, vesting period	3 years
Number of stock options exchanged, outstanding	527,624
Number of stock options exchange percentage	75.00%
Replacement stock options exercise price | $ / shares	$ 3.04
Incremental compensation expense during period under option exchange | $	$ 4,700
Unrecognized compensation costs | $	$ 141,000
Weighted average period	3 years

Preferred Stock, Common Stock36

Preferred Stock, Common Stock and Stockholders' Equity - Summary of Stock Option Activity (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Outstanding beginning balance	683,500
Shares, Granted	354,000
Shares, Outstanding ending balance	1,037,500	683,500
Shares, Vested and expected to vest at December 31, 2015	1,037,500
Shares, Exercisable at December 31, 2015	530,079
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Outstanding beginning balance	$ 7.67
Weighted Average Exercise Price, Granted	6.25
Weighted Average Exercise Price, Outstanding ending balance	7.19	$ 7.67
Weighted Average Exercise Price, Vested and expected to vest at December 31, 2015	7.19
Weighted Average Exercise Price, Exercisable at December 31, 2015	$ 6.80
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding, Weighted Average Remaining Contractual Term [Abstract]
Weighted Average Remaining Contractual Term (Years), Outstanding	8 years 15 days	8 years 5 months 12 days
Weighted Average Remaining Contractual Term (Years), Granted	9 years 2 months 12 days
Weighted Average Remaining Contractual Term (Years), Vested and expected to vest at December 31, 2015	8 years 15 days
Weighted Average Remaining Contractual Term (Years), Exercisable at December 31, 2015	7 years 6 months
Share Based Compensation Arrangement by Share Based Payment Award Options Outstanding, Aggregate Intrinsic Value [Abstract]
Aggregate Intrinsic Value, Outstanding beginning balance	$ 649,000
Aggregate Intrinsic Value, Outstanding ending balance	342,200	$ 649,000
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2015	342,200
Aggregate Intrinsic Value, Exercisable at December 31, 2015	$ 342,200

Preferred Stock, Common Stock37

Preferred Stock, Common Stock and Stockholders' Equity - Summary of Nonvested Options Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Shares Nonvested , Outstanding beginning balance	424,419
Shares, Granted	354,000
Shares Vested	(270,998)
Shares Nonvested , Outstanding ending balance	507,421	424,419
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted Average Grant Date Fair Value Per Share, Nonvested beginning balance	$ 9.02
Weighted Average Grant Date Fair Value Per Share, Granted	4.03	$ 4.76
Weighted Average Grant Date Fair Value Per Share, Vested	8.07
Weighted Average Grant Date Fair Value Per Share, Nonvested ending balance	$ 7.60	$ 9.02

Preferred Stock, Common Stock38

Preferred Stock, Common Stock and Stockholders' Equity - Summary of Estimated Fair Value of Stock Option Award (Detail) - Stock Options [Member]	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Minimum [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	1.50%	1.66%
Expected option term	5 years 6 months	5 years 6 months
Expected volatility of common stock	71.99%	71.06%
Maximum [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	1.87%	1.77%
Expected option term	6 years	6 years
Expected volatility of common stock	76.74%	73.21%

Preferred Stock, Common Stock39

Preferred Stock, Common Stock and Stockholders' Equity - Stock-Based Compensation and Employee Stock Purchase Plan - Additional Information (Detail) - USD ($) $ in Millions	Jan. 02, 2016	Jun. 13, 2013	Dec. 31, 2015	Dec. 31, 2014	Jan. 01, 2016
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs			$ 2.3
Weighted average period			1 year 1 month 17 days
Common stock reserved for issuance			1,276,765	1,043,457
Issuance of common stock from employee stock purchase plan, Shares			41,176	7,294
Employee stock purchase plan [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock as percentage of fair market value		85.00%
Percentage of deduction of eligible compensation		20.00%
Common stock reserved for issuance		30,000	41,530
Shares of common stock available for issuance description			In addition, the number of shares of common stock available for issuance under the ESPP is annually increased on the first day of each fiscal year during the term of the ESPP by an amount equal to the lesser of: (i) 30,000 shares; (ii) one percent of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (iii) such other amount as the Company’s board of directors may determine.
Reserve percentage for issuance of shares		100.00%
ESPP approval date		Aug. 29, 2013
Subsequent Event [Member] | Employee stock purchase plan [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance					71,530
Stock issued during period, shares, period increase	30,000

Preferred Stock, Common Stock40

Preferred Stock, Common Stock and Stockholders' Equity - Summary of Estimated Fair Value of Employee Stock Purchase Plan Award (Detail) - Employee stock purchase plan [Member]	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option term	6 months	6 months
Expected dividend yield	0.00%	0.00%
Minimum [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	0.08%	0.05%
Expected volatility of common stock	62.91%	69.32%
Maximum [Member]
Stock-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	0.26%	0.08%
Expected volatility of common stock	69.64%	73.21%

Preferred Stock, Common Stock41

Preferred Stock, Common Stock and Stockholders' Equity - Summary of Recognized Non-Cash Stock-Based Compensation Expense (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,504,356	$ 1,102,087
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	579,078	410,150
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 925,278	$ 691,937

Preferred Stock, Common Stock42

Preferred Stock, Common Stock and Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2015	Dec. 31, 2014
Common Stock Reserved for Future Issuance [Line Items]
Stock options issued and outstanding	1,037,500	683,500
Authorized for future option grants	78,854	188,370
Warrants to purchase common stock	118,881	118,881
Total common stock reserved for future issuance	1,276,765	1,043,457
Authorized for Employee Stock Purchase Plan [Member]
Common Stock Reserved for Future Issuance [Line Items]
Total common stock reserved for future issuance	41,530	52,706

Employee Benefit Plan - Additio

Employee Benefit Plan - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Eligible age for employees for participating in the plan	21 years
Company's contributions to employee benefit plan	$ 0	$ 20,000
Future
Defined Benefit Plan Disclosure [Line Items]
Company's contributions to employee benefit plan	$ 6,700

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Accrual on interest and penalties related to income taxes	$ 0	$ 0
Net operating loss carryforwards	$ 17,400,000
Cumulative change in ownership for limitation of use of net operating loss and research and development credit carryforwards	50.00%
Period of cumulative change of ownership	3 years
Research and development credit	$ 2,100,000
Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards	$ 43,900,000
Expiry date of carry forwards	Dec. 31, 2027
Tax credit carry forwards	$ 1,500,000
California [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards	$ 42,900,000
Expiry date of carry forwards	Dec. 31, 2017
Tax credit carry forwards	$ 1,000,000
Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax years subject to examination by taxing authorities	2,007

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Federal Statutory Income Tax Rate and Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal statutory rate	34.00%	34.00%
Change in valuation allowance	(1.60%)	(1.60%)
State income taxes, net of federal effect	5.80%	5.80%
Research and development credits	4.10%	5.00%
Removal of net operating loss and other credits	(39.20%)	(41.20%)
Stock compensation and other permanent items	(3.10%)	(2.00%)
Effective income tax rate	0.00%	0.00%

Income Taxes - Summary of Signi

Income Taxes - Summary of Significant Components of Deferred Tax Assets (Detail) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Acquired technology	$ 276,000	$ 317,000
Stock compensation expense	430,000	223,000
Accruals and other	124,000	105,000
Total deferred tax assets	830,000	645,000
Less valuation allowance	$ (830,000)	$ (645,000)

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - Clinical Trial Services - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Fee incurred for clinical trial services	$ 218,000	$ 255,000
Accounts Payable	$ 0	$ 22,000

Summarized Quarterly Data - Sum

Summarized Quarterly Data - Summarized Quarterly Data (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Research and development expense	$ 1,708,302	$ 1,837,743	$ 2,188,138	$ 2,419,961	$ 2,176,388	$ 3,088,373	$ 2,874,977	$ 1,852,116	$ 8,154,144	$ 9,991,855
General and administrative expense	842,777	819,703	976,418	1,025,261	738,012	732,800	616,888	1,070,479	3,664,159	3,158,179
Net loss	$ (2,624,152)	$ (2,735,400)	$ (3,241,163)	$ (3,520,748)	$ (2,919,803)	$ (3,825,354)	$ (3,547,040)	$ (2,955,484)	$ (12,121,463)	$ (13,247,681)
Net loss per common share, basic and diluted	$ (0.37)	$ (0.42)	$ (0.52)	$ (0.58)	$ (0.48)	$ (0.63)	$ (0.59)	$ (0.49)	$ (1.87)	$ (2.20)
Weighted average shares outstanding, basic and diluted	7,123,163	6,494,845	6,212,803	6,103,783	6,065,841	6,054,250	6,027,672	6,002,936	6,485,794	6,032,560