Viking Therapeutics (VKTX) 10-K 21 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 28, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	VKTX
Entity Registrant Name	Viking Therapeutics, Inc.
Entity Central Index Key	1,607,678
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		23,825,425
Entity Public Float			$ 14,172,784

Balance Sheets

Balance Sheets - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 3,075,502	$ 768,550
Short-term investments – available for sale	10,075,058	13,335,499
Prepaid expenses and other current assets	824,269	1,097,599
Total current assets	13,974,829	15,201,648
Deferred public offering and other financing costs	521,538	157,455
Deposits	39,341	80,000
Total assets	14,535,708	15,439,103
Current liabilities:
Accounts payable	1,203,888	592,414
Other accrued liabilities	1,237,122	1,384,398
Accrued interest	34,894
Convertible notes payable, current portion (net of discount of $675,589 and $0 at December 31, 2016 and 2015, respectively)	3,269,582
Debt conversion feature liability	731,048
Total current liabilities	6,476,534	1,976,812
Accrued interest, non-current		183,611
Convertible notes payable (net of discount of $0 and $348,460 at December 31, 2016 and 2015, respectively)		2,151,540
Debt conversion feature liability	731,048	2,370,903
Deferred rent	16,307	31,239
Total long-term liabilities	16,307	4,737,293
Total liabilities	6,492,841	6,714,105
Commitments and contingencies (Note 12)
Stockholders’ equity:
Preferred stock, $0.00001 par value: 10,000,000 shares authorized at December 31, 2016 and 2015; no shares issued and outstanding at December 31, 2016 and 2015
Common stock, $0.00001 par value: 300,000,000 shares authorized at December 31, 2016 and 2015; 20,823,873 shares issued and outstanding at December 31, 2016 and 9,683,741 shares issued and outstanding at December 31, 2015	208	97
Additional paid-in capital	68,326,818	54,277,716
Accumulated deficit	(60,277,267)	(45,545,445)
Accumulated other comprehensive loss	(6,892)	(7,370)
Total stockholders’ equity	8,042,867	8,724,998
Total liabilities and stockholders’ equity	$ 14,535,708	$ 15,439,103

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Convertible notes payable, discount, current portion	$ 675,589	$ 0
Convertible notes payable, discount, noncurrent portion	$ 0	$ 348,460
Preferred stock, par value	$ 0.00001	$ 0.00001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	20,823,873	9,683,741
Common stock, shares outstanding	20,823,873	9,683,741

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues	$ 0	$ 0
Operating expenses:
Research and development	9,000,499	6,966,842
General and administrative	4,846,776	5,029,636
Total operating expenses	13,847,275	11,996,478
Loss from operations	(13,847,275)	(11,996,478)
Other income (expense):
Change in fair value of accrued license fees		(9,381,848)
Change in fair value of debt conversion feature liability	1,064,170	(1,043,478)
Amortization of debt discount	(1,788,088)	(893,502)
Amortization of financing costs	(138,701)
Interest expense, net	(21,928)	(88,682)
Total other income (expense)	(884,547)	(11,407,510)
Net loss	(14,731,822)	(23,403,988)
Other comprehensive gain (loss), net of tax:
Unrealized gain (loss) on securities	478	(7,370)
Comprehensive loss	$ (14,731,344)	$ (23,411,358)
Basic and diluted net loss per share	$ (0.90)	$ (3.68)
Weighted-average shares used to compute basic and diluted net loss per share	16,278,292	6,355,869

Statements of Stockholders' Equ

Statements of Stockholders' Equity (Deficit) - USD ($)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2014	$ (22,128,531)	$ 60	$ 12,866		$ (22,141,457)
Balance (in shares) at Dec. 31, 2014		6,000,000
Repurchase of common stock	(38)	$ (38)
Repurchase of common stock (in shares)		(3,802,859)
Employee stock-based compensation, net	2,205,676	$ 3	2,205,673
Employee stock-based compensation, net (in shares)		318,708
Issuance of common stock to consultant	28,760		28,760
Issuance of common stock to consultant (in shares)		4,882
Conversion of debt to equity	456,412	$ 1	456,411
Conversion of debt to equity (in shares)		57,046
Issuances of common stock to related party	29,247,711	$ 36	29,247,675
Issuances of common stock to related party (in shares)		3,655,964
Initial public offering, net of issuance costs	22,326,366	$ 35	22,326,331
Initial public offering, net of issuance costs (in shares)		3,450,000
Unrealized gain (loss) on investments	(7,370)			$ (7,370)
Net loss	(23,403,988)				(23,403,988)
Balance at Dec. 31, 2015	8,724,998	$ 97	54,277,716	(7,370)	(45,545,445)
Balance (in shares) at Dec. 31, 2015		9,683,741
Employee stock-based compensation, net	1,785,326		1,785,326
Employee stock-based compensation, net (in shares)		(43,166)
Conversion of debt to equity	1,200,000	$ 9	1,199,991
Conversion of debt to equity (in shares)		960,000
Sale of common stock, net of issuance costs	11,063,887	$ 102	11,063,785
Sale of common stock, net of issuance costs (in shares)		10,223,298
Unrealized gain (loss) on investments	478			478
Net loss	(14,731,822)				(14,731,822)
Balance at Dec. 31, 2016	$ 8,042,867	$ 208	$ 68,326,818	$ (6,892)	$ (60,277,267)
Balance (in shares) at Dec. 31, 2016		20,823,873

Statements of Cash Flows

Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net loss	$ (14,731,822)	$ (23,403,988)
Adjustments to reconcile net loss to net cash used in operating activities
Amortization of debt discount on notes payable	1,788,088	893,502
Amortization of investment premiums	153,735	131,899
Amortization of financing costs	138,701
Change in fair value of accrued license fees		9,381,848
Change in fair value of debt conversion feature liability	(1,064,170)	1,043,478
Stock-based compensation	1,794,327	2,601,448
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	273,329	(1,079,772)
Deposits	40,659	(79,225)
Accounts payable	677,185	219,237
Accrued expenses	(141,295)	1,560,079
Net cash used in operating activities	(11,071,263)	(8,731,494)
Cash flows from investing activities
Purchases of investments	(16,922,235)	(16,033,042)
Proceeds from sales and maturities of investments	19,952,000	2,563,000
Net cash provided by (used in) investing activities	3,029,765	(13,470,042)
Cash flows from financing activities
Proceeds from issuances of common stock, net of underwriting discounts and commissions	11,548,518	25,392,500
Public offering and financing costs	(1,096,205)	(2,782,462)
Value of shares withheld related to employee tax withholding	(31,061)	(418,412)
Repurchases of common stock	(229)	(38)
Repayment of convertible notes payable	(94,861)
Proceeds from stock issuance under employee stock purchase plan	22,288	22,641
Net cash provided by financing activities	10,348,450	22,214,229
Net increase in cash and cash equivalents	2,306,952	12,693
Cash and cash equivalents beginning of period	768,550	755,857
Cash and cash equivalents end of period	3,075,502	768,550
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	205,139
Supplemental disclosure of non-cash investing and financing transactions
Shares issued in lieu of loan payment to related party	1,200,000
Shares issued as commitment fee in connection with Aspire agreement	$ 440,278
Shares issued in lieu of license fee payment		29,247,711
Unpaid deferred public offering and other financing costs		108,791
Conversion of notes payable		456,412
Issuance of common stock to consultant		$ 28,760

Organization, Liquidity and Man

Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies	1. Organization, Liquidity and Management’s Plan, and Summary of Significant Accounting Policies The Company Viking Therapeutics, Inc., a Delaware corporation (the “Company”), is a clinical-stage biopharmaceutical company focused on the development of novel therapies for metabolic and endocrine disorders. The Company was incorporated under the laws of the State of Delaware on September 24, 2012 and its principal executive offices are located in San Diego, CA. Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying financial statements. Significant estimates made in preparing these financial statements relate to determining the fair value of the debt conversion feature liability and accounting for certain commitments. Actual results could differ from those estimates. Cash and Cash Equivalents The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents. Investments Available-for-Sale Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. The amortization of premiums and accretion of discounts is included in interest income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income (expense). The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentration of credit risk, consist primarily of cash and cash equivalents and marketable securities. The Company maintains deposits in federally insured depository institutions in excess of federally insured limits. Management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. Additionally, the Company has established guidelines regarding approved investments and maturities of investments, which are designed to maintain safety and liquidity. Liquidity and Management’s Plan In accordance with Accounting Standards Update In April 2016, the Company completed an underwritten public offering of its common stock and warrants to purchase shares of its common stock (the “Offering”) pursuant to a registration statement on Form S-1 (File No. 333-208182). In the Offering, the Company sold 8,625,000 shares of its common stock and warrants to purchase up to 8,625,000 shares of its common stock at a public offering price of $1.25 per share of common stock and related warrant. The warrants have an exercise price of $1.50 per share of common stock, were immediately exercisable upon issuance and will expire on April 13, 2021. Upon the closing of the Offering in April 2016, the Company received net proceeds of $9,037,686, after deducting underwriting discounts, commissions and other offering expenses of $1,743,564. On June 20, 2016, the Company entered into an Equity Distribution Agreement (the “Distribution Agreement”) with Maxim Group LLC, as sales agent (“Maxim”), pursuant to which the Company may offer and sell, from time to time, through Maxim (the “Maxim Offering”), up to 3,748,726 shares of its common stock. During the year ended December 31, 2016, the Company sold 778,849 shares of its common stock under the Distribution Agreement resulting in net proceeds to the Company of $956,518, after deducting the sales agent’s commission. On August 24, 2016, the Company entered into a Common Stock Purchase Agreement (the “Purchase Agreement”) with Aspire Capital Fund, LLC (“Aspire Capital”), pursuant to which Aspire Capital committed to purchase up to an aggregate of $12.5 million of shares of the Company’s common stock over the 30-month term of the Purchase Agreement. Upon execution of the Purchase Agreement, the Company issued and sold to Aspire Capital under the Purchase Agreement 333,333 shares of common stock (the “Initial Shares”) at a price per share of $1.50, for an aggregate purchase price of $500,000. Concurrently with the execution of the Purchase Agreement, and as consideration for Aspire Capital entering into the Purchase Agreement, the Company issued to Aspire Capital 336,116 shares of common stock as a commitment fee (the “Commitment Shares”). Pursuant to the terms of the Purchase Agreement, the Company may, from time to time and subject to certain limitations, direct Aspire Capital to purchase shares of the Company’s common stock using pricing formulas based on average prevailing market prices around the time of each sale. During the year ended December 31, 2016, 150,000 shares were issued pursuant to the Purchase Agreement resulting in aggregate gross proceeds of $173,250, in addition to the Initial Shares and the Commitment Shares. Although it is difficult to predict the Company’s liquidity requirements, as of December 31, 2016, and based upon the Company’s current operating plan, the Company does not believe that it will have sufficient cash to meet its projected operating requirements for at least the next 12 months following the issuance of the financial statements unless it raises additional capital. As of December 31, 2016, the Company had an accumulated deficit of $60,277,267. These losses have resulted principally from research and development costs incurred in connection with acquiring the exclusive worldwide rights to the portfolio of five drug candidates from Ligand Pharmaceuticals Incorporated (“Ligand”) and the related non-cash interest expense recorded for increases in the deemed fair market value for the license fees payable to Ligand, research and development expenses related to the manufacturing of clinical drug product and clinical development of VK5211, VK2809 and VK0214, consulting fees and general and administrative expenses. The Company anticipates that it will continue to incur net losses for the foreseeable future as it continues the development of its clinical drug candidates and preclinical programs and incurs additional costs associated with being a public company. Deferred Financing Costs Deferred financing costs represent legal, accounting and other direct costs related to the Company’s efforts to raise capital through a public or private sale of the Company’s common stock. Costs related to the public sale of the Company’s common stock are deferred until the completion of the applicable offering, at which time such costs are reclassified to additional paid-in-capital as a reduction of the proceeds. Costs related to the private sale of the Company’s common stock are deferred until the completion of the applicable offering, at which time such costs are amortized over the term of the applicable purchase agreement. Revenue Recognition The Company has not recorded any revenues since its inception. However, in the future, the Company may enter into collaborative research and licensing agreements, under which the Company could be eligible for payments made in the form of upfront license fees, research funding, cost reimbursement, contingent event-based payments and royalties. Revenue from upfront, nonrefundable license fees is recognized over the period that any related services are provided by the Company. Amounts received for research funding are recognized as revenue as the research services that are the subject of such funding are performed. Revenue derived from reimbursement of research and development costs in transactions where the Company acts as a principal are recorded as revenue for the gross amount of the reimbursement, and the costs associated with these reimbursements are reflected as a component of research and development expense in the statements of operations. The Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) Topic 605-28, Revenue Recognition – Milestone Method (“ASC 605-28”), established the milestone method as an acceptable method of revenue recognition for certain contingent event-based payments under research and development arrangements. Under the milestone method, a payment that is contingent upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved. A milestone is an event (1) that can be achieved based in whole or in part on either the Company’s performance or on the occurrence of a specific outcome resulting from the Company’s performance, (2) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved, and (3) that would result in additional payments being due to the Company. The determination that a milestone is substantive is subject to management’s judgment and is made at the inception of the arrangement. Milestones are considered substantive when the consideration earned from the achievement of the milestone is (a) commensurate with either the Company’s performance to achieve the milestone or the enhancement of value of the item delivered as a result of a specific outcome resulting from the Company’s performance to achieve the milestone, (b) relates solely to past performance, and (c) is reasonable relative to all deliverables and payment terms in the arrangement. Other contingent event-based payments received for which payment is either contingent solely upon the passage of time or the results of a collaborative partner’s performance are not considered milestones under ASC 605-28. In accordance with ASC Topic 605-25, Revenue Recognition – Multiple-Element Arrangements Research and Development Expenses All costs of research and development are expensed in the period incurred. Research and development costs primarily consist of fees paid to contract research organizations (“CROs”) and clinical trial sites, employee and consultant related expenses, which include salaries, benefits and stock-based compensation for research and development personnel, external research and development expenses incurred pursuant to agreements with third-party manufacturing organizations, facilities costs, travel costs, dues and subscriptions, depreciation and materials used in preclinical studies, clinical trials and research and development. The Company estimates its preclinical study and clinical trial expenses based on the services it received pursuant to contracts with research institutions and CROs that conduct and manage preclinical studies and clinical trials on the Company’s behalf. Clinical trial-related contracts vary significantly in length, and may be for a fixed amount, based on milestones or deliverables, a variable amount based on actual costs incurred, capped at a certain limit, or for a combination of these elements. The Company accrues service fees based on work performed, which relies on estimates of total costs incurred based on milestones achieved, patient enrollment and other events. The majority of the Company’s service providers invoice the Company in arrears, and to the extent that amounts invoiced differ from its estimates of expenses incurred, the Company accrues for additional costs. The financial terms of these agreements vary from contract to contract and may result in uneven expenses and payment flows. Preclinical study and clinical trial expenses include: • fees paid to CROs, consultants and laboratories in connection with preclinical studies; • fees paid to CROs, clinical trial sites, investigators and consultants in connection with clinical trials; and • fees paid to contract manufacturers and service providers in connection with the production, testing and packaging of active pharmaceutical ingredients and drug materials for preclinical studies and clinical trials. Payments under some of these agreements depend on factors such as the milestones accomplished, including enrollment of certain numbers of patients, site initiation and the completion of clinical trial milestones. To date, the Company has not experienced any events requiring it to make material adjustments to its accruals for service fees. If the Company does not identify costs that it has begun to incur or if it underestimates or overestimates the level of services performed or the costs of these services, its actual expenses could differ from its estimates which could materially affect its results of operations. Adjustments to the Company’s accruals are recorded as changes in estimates become evident. Furthermore, based on amounts invoiced to the Company by its service providers, the Company may also record payments made to those providers as prepaid expenses that will be recognized as expense in future periods as services are rendered. In May 2014, the Company entered into the Master License Agreement, pursuant to which it acquired certain rights to a number of research and development programs from Ligand. In doing so, the Company updated its policy on research and development to include the purchase of rights to intangible assets. In accordance with ASC Topic 730, Research and Development, Patent Costs Costs related to filing and pursuing patent applications are expensed as incurred to general and administrative expense, as recoverability of such expenditures is uncertain. Stock-Based Compensation The Company generally uses the straight-line or graded vesting method to allocate compensation cost to reporting periods over each optionee’s requisite service period, which is generally the vesting period, and estimates the fair value of stock-based awards or restricted stock units to employees and directors using the Black-Scholes option-valuation model. For options with a graded vesting schedule, the Company uses the graded vesting schedule to allocate compensation cost to reporting periods. The Black-Scholes model requires the input of subjective assumptions, including volatility, the expected term and the fair value of the underlying common stock on the date of grant, among other inputs. Stock options granted to non-employees are accounted for using the fair value approach. Stock options granted to non-employees are subject to periodic revaluation over their vesting terms. For restricted stock and restricted stock unit awards, the Company generally uses the straight-line or graded vesting method to allocate compensation cost to reporting periods over the holder’s requisite service period, which is generally the vesting period, and uses the fair value at grant date to value the awards. For restricted stock that vests upon the satisfaction of certain performance conditions, the Company recognizes stock-based compensation expense when it becomes probable that the performance conditions will be met. At the point that it becomes probable that the performance conditions will be met, the Company records a cumulative catch-up of the expense from the grant date to the current date, and the Company then amortizes the remainder of the expense over the remaining service period. Prior to the Company’s initial public offering of its common stock (the “IPO”), the Company accounted for stock-based compensation by measuring and recognizing compensation expense for all stock-based payments made to employees and directors based on estimated award date fair values, which estimates were highly complex and subjective in nature. The Company used the straight-line or graded vesting method to allocate compensation cost to reporting periods over each restricted award’s requisite service period, which was generally the vesting period, and estimated the fair value of restricted stock-based awards to employees and consultants using a Monte Carlo market approach simulation method and performed an allocation of value to common stock based on the estimated time to a liquidity event. In addition, the Company accounted for performance-based restricted stock awards to employees by determining the fair value of the restricted stock award at the date of issuance by using the Probability Weighted Expected Return Method (“PWERM”) and then assessing at each balance sheet date the probability of the performance criteria being met. If the probability of achieving the criteria was deemed less-than-probable, then no expense was recorded. At the point where the criteria were deemed probable of being met, the Company then began recording stock-based compensation with a cumulative catch-up expense in the period first recognized and then on a straight-line basis over the remaining period for which the performance criteria were expected to be completed. Income Taxes The Company accounts for its income taxes using the liability method whereby deferred tax assets and liabilities are determined based on temporary differences between the basis used for financial reporting and income tax reporting purposes. Deferred income taxes are provided based on the enacted tax rates in effect at the time such temporary differences are expected to reverse. A valuation allowance is provided for deferred tax assets if it is more likely than not that the Company will not realize those tax assets through future operations. ASC Topic 740-10, Income Taxes The Company’s policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. Net Loss per Common Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, the Company currently does not have any deemed common share equivalents; therefore, its basic and diluted net loss per share calculations are the same. The following table presents the computation of basic and diluted net loss per common share: Year Ended December 31, 2016 2015 Historical net loss per share Numerator Net loss attributable to common stockholders $ (14,731,822 ) $ (23,403,988 ) Denominator Weighted-average common shares outstanding 16,767,235 8,514,155 Less: Weighted-average shares subject to repurchase (488,943 ) (2,158,286 ) Denominator for basic and diluted net loss per share 16,278,292 6,355,869 Basic and diluted net loss per share $ (0.90 ) $ (3.68 ) Potentially dilutive securities that are not included in the calculation of diluted net loss per share because their effect is anti-dilutive are as follows (in common equivalent shares): Year Ended December 31, 2016 2015 Common stock warrants 9,667,500 82,500 Restricted stock units 80,625 75,750 Common stock subject to repurchase 307,096 667,963 Common stock options 883,837 365,394 Shares issuable upon conversion of debt 3,519,753 670,902 14,458,811 1,862,509 Segments The Company operates in only one segment. Management uses cash flows as the primary measure to manage its business and does not segment its business for internal reporting or decision making purposes. Recent Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. The FASB has subsequently issued the following amendments to ASU No. 2014-09, which have the same effective date and transition date of January 1, 2018: • In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers • In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers • In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers • In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers • In December 2016, the FASB issued ASU No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which amends certain narrow aspects of the guidance issued in ASU No. 2014-09 including guidance related to the disclosure of remaining performance obligations and prior-period performance obligations, as well as other amendments to the guidance on loan guarantee fees, contract costs, refund liabilities, advertising costs and the clarification of certain examples. The Company will continue to evaluate the potential impact that these standards will have on its financial position and results of operations, although there is no current impact of this new guidance on its financial statements as the Company does not currently have any revenue generating arrangements. In February 2016, the FASB issued ASU No. 2016-02, Leases for the Company in the first quarter of fiscal year 2019 and early adoption is permitted. ASU 2016-02 is required to be applied with a modified retrospective approach and requires application of the new standard at the beginning of the earliest comparative period presented. The Company does not expect the adoption of ASU 2016-02 to have a material effect on its financial statements and related disclosures. In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-based Payment Accounting simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. Under this guidance, a company recognizes all excess tax benefits and tax deficiencies as income tax expense or benefit in the statement of operations. This change eliminates the notion of the additional paid-in capital pool and reduces the complexity in accounting for excess tax benefits and tax deficiencies. In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments The Company is evaluating the effect that ASU 2016-13 will have on its financial statements and related disclosures. In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments

Investments in Marketable Secur

Investments in Marketable Securities	12 Months Ended
	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Investments in Marketable Securities	2. Investments in Marketable Securities The Company’s investment strategy is focused on capital preservation. The Company invests in instruments that meet the credit quality standards outlined in the Company’s investment policy. This policy also limits the amount of credit exposure to any one issue or type of instrument. As of December 31, 2016 and 2015, the Company’s investments were in money market funds, certificates of deposit and corporate debt securities. There were no sales of available-for-sale securities during the year ended December 31, 2016 and 2015. Investments classified as available-for-sale as of December 31, 2016 consisted of the following: Amortized Cost Gross Unrealized Gains (1) Gross Unrealized Losses (1) Aggregate Estimated Fair Value Corporate debt securities (2) $ 10,081,950 $ — $ (6,892 ) $ 10,075,058 (1) Unrealized gains and losses on available-for-sale securities are included as a component of comprehensive loss. At December 31, 2016, there were 25 securities in an unrealized loss position. These unrealized losses were less than $1,000 individually and $7,000 in the aggregate. These securities have not been in a continuous unrealized loss position for more than 12 months. The Company does not intend to sell these investments and it is not more likely than not that the Company will be required to sell these investments before recovery of their amortized cost basis, which may be at maturity. The Company reviews its investments to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. ( 2 ) At December 31, 2016, none of these securities were classified as cash and cash equivalents on the Company’s balance sheet and none of these securities were scheduled to mature outside of one year. Investments classified as available-for-sale as of December 31, 2015 consisted of the following: Amortized Cost Gross Unrealized Gains (1) Gross Unrealized Losses (1) Aggregate Estimated Fair Value Certificates of deposit (2) $ 5,851,343 $ — $ — $ 5,851,343 Corporate debt securities (2) 7,491,526 — (7,370 ) 7,484,156 $ 13,342,869 $ — $ (7,370 ) $ 13,335,499 (1) Unrealized gains and losses on available-for-sale securities are included as a component of comprehensive loss. At December 31, 2015, there were 14 securities in an unrealized loss position. These unrealized losses were less than $2,000 individually and $8,000 in the aggregate. These securities have not been in a continuous unrealized loss position for more than 12 months. The Company does not intend to sell these investments and it is not more likely than not that the Company will be required to sell these investments before recovery of their amortized cost basis, which may be at maturity. The Company reviews its investments to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. (2) At December 31, 2015, none of these securities were classified as cash and cash equivalents on the Company’s balance sheet and none of these securities were scheduled to mature outside of one year.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	3. Fair Value of Financial Instruments The Company’s financial instruments consist of cash and cash equivalents, investments, accounts payable, debt and its related debt conversion feature liability. The carrying amounts reported in the accompanying balance sheets for cash and cash equivalents and accounts payable approximate fair value because of the short-term maturity of those instruments. Fair value measurements are classified and disclosed in one of the following three categories: Level 1 —Quoted prices in active markets for identical assets or liabilities. Level 2 —Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 —Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. As of December 31, 2016 and 2015, all of the Company’s financial assets that were subject to fair value measurements were valued using observable inputs. The Company’s financial assets valued based on Level 1 inputs consist of money market funds and certificates of deposit. The Company’s financial assets valued based on Level 2 inputs consist of corporate debt securities, which consist of investments in highly-rated investment-grade corporations. The Company’s financial liability that was subject to fair value measurement consisted of a debt conversion feature that has been recorded as a liability based on Level 3 unobservable inputs. The fair value of the debt conversion feature, current as of December 31, 2016 required management to estimate fair value based on the Black-Scholes-Merton option valuation model. The Black-Scholes-Merton option valuation model was adopted as a result of the Company’s entry in January 2016 into the the conversion terms of the the Loan and Security Agreement. The fair value of the debt conversion feature, long-term as of December 31, 2015 required management to estimate fair value based on assumed timing of conversion and an assumed annual discount rate. Alternate probabilities would have resulted in increases or decreases in the fair value of the debt conversion feature liability. The debt conversion feature embedded in each tranche of the Ligand Note is accounted for under ASC Topic 815 – Derivatives and Hedging The Company’s investment strategy is focused on capital preservation. The Company invests in instruments that meet the credit quality standards outlined in the Company’s investment policy. This policy also limits the amount of credit exposure to any one issue or type of instrument. As of December 31, 2016, the Company’s investments were in government money market funds and corporate debt securities. The fair values of the Company’s financial instruments are presented below: Fair Value Measurements at December 31, 2016 Total Level 1 Level 2 Level 3 Financial assets carried at fair value: Cash equivalents: Money market funds $ 2,519,322 $ 2,519,322 $ — $ — Short-term investments Corporate debt securities, available-for-sale 10,075,058 — 10,075,058 — Total financial assets $ 12,594,380 $ 2,519,322 $ 10,075,058 $ — Financial liabilities carried at fair value: Debt conversion feature - long-term $ 731,048 $ — $ — $ 731,048 Total financial liabilities $ 731,048 $ — $ — $ 731,048 Fair Value Measurements at December 31, 2015 Total Level 1 Level 2 Level 3 Financial assets carried at fair value: Cash equivalents: Money market funds $ 548,872 $ 548,872 $ — $ — Short-term investments Certificates of deposit 5,851,343 5,851,343 — — Corporate debt securities, available-for-sale 7,484,156 — 7,484,156 — Total financial assets $ 13,884,371 $ 6,400,215 $ 7,484,156 $ — Financial liabilities carried at fair value: Debt conversion feature - long-term $ 2,370,903 $ — $ — $ 2,370,903 Total financial liabilities $ 2,370,903 $ — $ — $ 2,370,903 The table below presents a summary of changes in the Company’s debt conversion feature liability measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the years ended December 31, 2016 and 2015: Year Ended December 31, 2016 2015 Debt conversion feature liability: Beginning balance $ 2,370,903 $ 1,449,211 Adjustments resulting from modification of debt (575,685 ) — Adjustments resulting from changes in fair value recognized in earnings (1,064,170 ) 1,043,478 Issuance of shares of common stock — (121,786 ) Ending balance $ 731,048 $ 2,370,903 The following table sets forth the Company’s valuation techniques and significant unobservable inputs used to determine fair value for significant Level 3 liabilities: Fair Value Significant Assets Liabilities Valuation Technique(s) Unobservable Input Range Debt conversion feature liability December 31, 2016 $ — $ 731,048 Black-Scholes-Merton option valuation model Volatility 61% Risk Free Rate 0.57% December 31, 2015 $ — $ 2,370,903 Discounted cash flow model Timing of the events 5/21/2016 Probabilities of Occurrence 100% Discount rate 37.5% Level 3 Fair Value Sensitivity Debt conversion feature liability As of December 31, 2016, the fair value of the debt conversion feature liability includes the estimated volatility and risk free rate. The higher/lower the estimated volatility, the higher/lower the value of the debt conversion feature liability. The higher/lower the risk free interest rate, the higher/lower the value of the debt conversion feature liability. As of December 31, 2015, the fair value of the debt conversion feature liability includes the estimated timing of the events, as well as the related probabilities of occurrence. The shorter/longer the period estimated to the event, the higher/lower the value of the debt conversion feature liability. The higher/lower the probability of occurrence, the higher/lower the value of the debt conversion feature liability.

Agreements with Ligand Pharmace

Agreements with Ligand Pharmaceuticals Incorporated	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Agreements with Ligand Pharmaceuticals Incorporated	4. Agreements with Ligand Pharmaceuticals Incorporated In May 2014, the Company entered into a master license agreement with Ligand, as amended (the “Master License Agreement”), pursuant to which, among other things, the Company acquired the rights to a number of research and development programs under patents related to the Company’s VK5211, VK2809, VK0214, VK0612, erythropoietin receptor (“EPOR”) and diacylglycerol acyltransferase-1 (“DGAT-1”) programs, related know-how controlled by Ligand and physical quantities of VK5211, VK2809, VK0214, VK0612, EPOR and DGAT-1 compounds. Pursuant to the terms of the Master License Agreement, the Company has the exclusive right and sole responsibility and decision-making authority for researching and developing any pharmaceutical products that contain or comprise one or any combination of the technology and compounds licensed from Ligand pursuant to the Master License Agreement (the “Licensed Products”). The Company also has the exclusive right and sole responsibility and decision-making authority to conduct all clinical trials and preclinical studies that the Company believes are appropriate to obtain the regulatory approvals necessary for commercialization of the Licensed Products, and the Company will own and maintain all regulatory filings and all regulatory approvals for the Licensed Products. Additionally, pursuant to the terms of the Master License Agreement, the Company has the sole decision-making authority and responsibility and the exclusive right to commercialize any of the Licensed Products, either by itself or, in certain circumstances, through sublicensees selected by the Company. The Company also has the exclusive right to manufacture or have manufactured any Licensed Product itself or, in certain circumstances, through sublicensees or third parties selected by the Company. The Company will own any intellectual property that it develops in connection with the license granted under the Master License Agreement. As partial consideration for the grant of the rights and licenses to the Company under the Master License Agreement, the Company issued to Ligand at the closing of the IPO 3,655,964 shares of its common stock having an estimated aggregate value of $29.2 million. Furthermore, as partial consideration for the grant of the rights and licenses to the Company under the Master License Agreement the Company entered into the Loan and Security Agreement with Ligand. As further partial consideration for the grant of the rights and licenses to the Company by Ligand under the Master License Agreement, the Company has agreed to pay to Ligand certain one-time, non-refundable milestone payments in connection with the Licensed Products of up to $1.54 billion in the aggregate upon the achievement of certain development, regulatory and sales milestones. The Company will also pay to Ligand royalties on aggregate annual worldwide net sales of Licensed Products by the Company, its affiliates and its sublicensees at tiered percentage rates from the low-to-upper single digits based upon net sales. The term of the Master License Agreement will continue unless the agreement is terminated by the Company or Ligand, and each of the Company and Ligand have the right to terminate the Master License Agreement in certain circumstances, including, without limitation, if the other party defaults on certain of its obligations under the Master License Agreement. Ligand has the right to terminate the Master License Agreement under certain circumstances, including, but not limited to: (1) in the event of the Company’s insolvency or bankruptcy, (2) if the Company does not pay an undisputed amount owing under the Master License Agreement when due and fails to cure such default within a specified period of time, or (3) if the Company defaults on certain of its material and substantial obligations and fails to cure the default within a specified period of time. The Company has the right to terminate the Master License Agreement under certain circumstances, including, but not limited to: (i) if Ligand does not pay an undisputed amount owing under the Master License Agreement when due and fails to cure such default within a specified period of time, or (ii) if Ligand defaults on certain of its material and substantial obligations and fails to cure the default within a specified period of time. In addition, provisions of the Master License Agreement can be terminated on a licensed program-by-program basis under certain circumstances. In the event that the Master License Agreement is terminated in its entirety or with respect to a specific licensed program for any reason: (A) all licenses granted to the Company under the Master License Agreement (or with respect to the specific licensed program) will terminate and the Company will, upon Ligand’s request (subject to Ligand assuming legal responsibility for any clinical trials of the Licensed Products then ongoing), assign and transfer to Ligand (or to such transferee as Ligand may direct), at no cost to Ligand, all regulatory documentation and all regulatory approvals prepared or obtained by the Company or on its behalf related to the Licensed Products (or those related to the specific licensed program), or, if Ligand does not make such a request, the Company will wind down any ongoing clinical trials with respect to the Licensed Products (or those related to the specific licensed program) at no cost to Ligand; (B) the Company will, upon Ligand’s request, sell and transfer to Ligand (or to such transferee as Ligand may direct), at a price equal to 125% of the Company’s costs of goods, any and all chemical, biological or physical materials relating to or comprising the Licensed Products (or those related to the specific licensed program); (C) the Company will have, for a period of six months following termination, the right to sell on the normal business terms in existence before such termination any finished commercial inventory of Licensed Products (or those related to the specific licensed program) which remains on hand, so long as the Company pays to Ligand the applicable royalties and sales milestones; (D) Ligand has the right to require the Company to assign to Ligand the trademarks owned by the Company relating to the Licensed Products (or those related to the specific licensed program); and (E) the Company will grant to Ligand a non-exclusive, worldwide, royalty-bearing sublicensable license under any patent rights and know-how controlled by the Company to the extent necessary to make, have made, import, use, offer to sell and sell the Licensed Products (or those related to the specific licensed program) anywhere in the world at a royalty rate in the low single digits. Under the Master License Agreement, the Company has agreed to indemnify Ligand for claims relating to the performance of the Company’s obligations under the Master License Agreement, any breach of the representations and warranties made by the Company under the Master License Agreement, clinical trials conducted by the Company and the research, development and commercialization of the Licensed Products by the Company and its affiliates, sublicensees, distributors and agents. In addition, Ligand has agreed to indemnify the Company for claims relating to the performance of its obligations under the Master License Agreement, its breach of representations and warranties under the agreement and its research and development of the licensed compounds before the effective date of the Master License Agreement. Each party’s indemnification obligations will not apply to the extent the claims result from the negligence or willful misconduct of the indemnified party or any of its employees, agents, officers or directors or from the indemnified party’s breach of its representations or warranties set forth in the Master License Agreement. On September 6, 2014, the Company and Ligand entered into an amendment to the Master License Agreement pursuant to which the parties agreed to certain modifications to the calculations used to determine the number of shares issuable to Ligand pursuant to the Master License Agreement. As a result of the modification, the Company incurred an incremental charge to research and development expense of $517,960 and a corresponding increase in the accrued license fees. In connection with entering into the Master License Agreement with Ligand, the Company entered into the Loan and Security Agreement, pursuant to which, among other things, Ligand agreed to provide the Company with loans in the aggregate amount of up to $2.5 million. In May 2014, the Company also entered into a Management Rights Letter (the “Management Rights Letter”) with Ligand that requires the Company to expand the size of the Company’s board of directors to create an additional directorship on the Company’s board of directors and to allow Ligand to appoint an individual to fill the new directorship. The Management Rights Letter will terminate upon the earliest to occur of the liquidation or indefinite cessation of the Company’s business operations, the execution by the Company of a general assignment for the benefit of creditors or the appointment of a receiver or trustee to take possession of the Company’s property and assets, an acquisition of the Company by means of any transaction (including, without limitation, any reorganization, merger or consolidation) if the Company’s stockholders of record as constituted immediately prior to the transaction hold less than 50% of the voting power of the surviving or acquiring entity, or following the issuance of the Company’s securities pursuant to the Master License Agreement, the date that Ligand ceases to beneficially own at least 7.5% of the Company’s outstanding voting stock, or the date of May 21, 2024. The Company also entered into a Registration Rights Agreement (the “Registration Rights Agreement”) with Ligand in May 2014 for which the Company granted certain registration rights to Ligand with respect to the securities of the Company issued to Ligand pursuant to the Master License Agreement and the Ligand Note (collectively, the “Viking Securities”), the shares of the Company’s common stock issued or issuable upon conversion of the Viking Securities, if applicable, the shares of the Company’s common stock issued as a dividend or other distribution with respect to, in exchange for or in replacement of the Viking Securities and the shares of the Company’s capital stock issued upon conversion of the Ligand Note, or collectively, the Registrable Securities. Under the Registration Rights Agreement, the Company has agreed to file with the SEC, by no later than the first date on which the lock-up requested by the underwriters for the Company’s initial public offering expires or lapses with respect to Ligand (or the first business day thereafter), a registration statement on Form S-1 under the Securities Act that covers the resale of the full amount of the Registrable Securities. The Company has agreed to use commercially reasonable efforts to have the Registration Statement declared effective by the SEC as soon as practically possible after it is filed with the SEC. There are certain cash payment penalties that the Company may need to pay to Ligand if the Company does not meet certain timelines with the SEC. The Company has also agreed to use commercially reasonable efforts to keep each Registration Statement filed pursuant to the Registration Rights Agreement effective for certain periods of time. On January 22, 2016, the Company entered into a First Amendment to Registration Rights Agreement (the “Registration Rights Agreement Amendment”) with Ligand, which amends the Registration Rights Agreement. The Registration Rights Agreement Amendment extends the deadline by which the Company must file with the SEC a Registration Statement on Form S-1 (the “Registration Statement”) covering the resale of certain Company securities held by Ligand, including the shares of the Company’s common stock issuable to Ligand under the Amended Loan Agreement, by one year from January 23, 2016 to January 23, 2017, and extends the applicable deadline for seeking to have such Registration Statement declared effective by the SEC by one year. On February 14, 2017, the Company filed a Registration Statement on Form S-3 under the Securities Act covering the resale of the full amount of the Registrable Securities.

Accrued License Fees and Licens

Accrued License Fees and License Fees Expense	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accrued License Fees and License Fees Expense	5. Accrued License Fees and License Fees Expense As partial consideration for the grant of the rights and licenses to the Company under the Master License Agreement, the Company issued to Ligand at the closing of the Company’s IPO 3,655,964 shares of its common stock having an estimated aggregate value of $29.2 million. Prior to the IPO, the Company reported the expected issuance of stock to Ligand under the Master License Agreement as a liability in accordance with ASC Topic 480 , Distinguishing Liabilities from Equity, The fair value of the assets was determined using a PWERM, which incorporated relevant events and expected exit scenarios for the Company. The exit scenarios included an initial public offering, a merger or acquisition, which included an assumption of a Private Financing, and a scenario in which neither an initial public offering nor the merger or acquisition occurred. The enterprise value was based primarily on the market approach and probability-weighted expected exit values for the Company under each scenario. As of the execution of the Master License Agreement, the Company ascribed a percentage likelihood to each expected exit scenario, and each was less than 50%. However, since Ligand was entitled to receive shares under the Master License Agreement if either of these IPO or merger or acquisition scenarios were to occur, and the sum of the percentage likelihoods for the two exceeded 50%, the Company determined that a payout of shares was probable. Further, since the valuations would determine a value, the Company determined that the liability under the Master License Agreement should be reported as of the execution of the Master License Agreement. Similar publicly traded companies and merger or acquisition transactions were utilized as part of the market approach, and appropriate metrics were applied to the Company’s numbers along with qualitative comparable assessments. The Company utilized a Monte Carlo simulation method to determine the weighted average per share value as of the acquisition date and in accordance with the Master License Agreement, utilized that per share value to calculate the estimated license fee liability. During 2015, the Company revalued the license fee liability using the Company’s recent refocus to certain other programs; VK5211 to be used in hip fractures and VK0214 to be used in X-ALD and their updated fair values. On May 4, 2015, upon the closing of the Company’s IPO, the license fee liability was determined to be valued at $29,247,711 and the incremental amount of $9,381,848 was recorded as additional Other expense in the Company’s Statement of Operations for the period from January 1, 2015 through May 4, 2015. In accordance with the Master License Agreement, the Company issued 3,655,964 shares of its common stock having an estimated aggregate value equivalent to the May 4, 2015 license fee liability of $29,247,711 and offset this liability against its common stock and additional paid-in-capital.

Convertible Notes Payable

Convertible Notes Payable	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Convertible Notes Payable	6. Convertible Notes Payable Convertible notes payable consisted of the following at: December 31, 2016 2015 Current maturities: Convertible note payable issued during 2014 to Ligand pursuant to the Master License Agreement with a 5% annual interest rate, due during 2016 (amended in January 2016 to a 2.5% annual interest rate with maturity extended to 2017) $ 1,955,139 $ — Conversion payoff value 1,990,032 Discount on notes payable, current (675,589 ) — Convertible notes payable, current portion (net of discount) $ 3,269,582 $ — Long-term maturities: Convertible note payable issued during 2014 to Ligand pursuant to the Master License Agreement with a 5% annual interest rate, due during 2016 (amended in January 2016 to a 2.5% annual interest rate with maturity extended to 2017) $ — $ 2,500,000 Discount on notes payable, long-term — (348,460 ) Convertible notes payable, long-term (net of discount) $ — $ 2,151,540 Pursuant to the Loan and Security Agreement, among other things, Ligand provided the Company with loans in the aggregate amount of $2.5 million as of December 31, 2014. Up until January 21, 2016, the principal amount outstanding under the loans accrued interest at a fixed per annum rate equal to the lesser of 5.0% or the maximum interest rate permitted by law. Effective as of January 22, 2016, the principal amount outstanding under the loans accrue interest at a fixed per annum rate equal to the lesser of 2.5% or the maximum interest rate permitted by law. In the event the Company defaults under the loans, the loans will accrue interest at a fixed per annum rate equal to the lesser of 8% or the maximum interest rate permitted by law. The loans are evidenced by the Ligand Note. Pursuant to the terms of the Loan and Security Agreement and the Ligand Note, the loans will become due and payable upon the written demand of Ligand at any time after the earlier to occur of an event of default under the Loan and Security Agreement or the Ligand Note, or May 21, 2017 (the “Maturity Date”), unless the loans are repaid in cash or converted into equity prior to such time. In addition, under the Loan and Security Agreement, the Company may not declare or pay dividends in respect of its common stock without Ligand’s prior written consent. Additionally, pursuant to the terms of the Loan and Security Agreement, upon the consummation of the Company’s first bona fide capital financing transaction occurring after January 22, 2016, but prior to the Maturity Date, with aggregate net proceeds to the Company of at least $2,000,000 (the “Next Financing”), the Company was required to repay $1,500,000 of the Ligand Note obligation to Ligand, with at least $300,000 of such payment to be paid in cash (with any greater cash amount determined by the Company in its sole and absolute discretion), and the balance of the $1,500,000 payment (the “Balance”) to be paid in the form of such number of shares of the Company’s equity securities that are issued in the Next Financing as is equal to the quotient obtained by dividing the Balance by the lesser of (1) the lowest price per share paid by investors in the Next Financing (the “Financing Price”), and (2) $8.00 (subject to adjustment for stock dividends, splits, combinations or similar transactions). Each $1.00 of the $1,500,000 payment reduced the amount of accrued and unpaid interest and then unpaid principal amount of the loans under the Ligand Note by $0.50. As a result of an amendment to the Loan and Security Agreement entered into on January 22, 2016, which amended the conversion terms of the Ligand Note , beginning with the quarter ended March 31, 2016, management adopted the Black-Scholes-Merton option valuation model for the Ligand Note, resulting in a debt modification adjustment of $575,685 to the debt conversion feature liability offset with an adjustment recorded to the Ligand Note discount and conversion payoff value. On April 13, 2016, the Company completed an underwritten public offering of its common stock and warrants to purchase shares of its common stock resulting in net proceeds of $7,754,286, after deducting underwriting discounts, commissions and other offering expenses of $1,631,964. This offering constituted a Next Financing under the Loan and Security Agreement; therefore, the Company repaid $1,500,000 of the Ligand Note with $300,000 paid in cash and $1,200,000 paid in the form of 960,000 shares of its common stock (the “Ligand Shares”) and a warrant to purchase up to 960,000 shares of Company’s common stock (the “Ligand Warrant”). The Ligand Warrant has an exercise price of $1.50 per share of common stock, was immediately exercisable upon issuance and will expire on April 13, 2021. In addition, the Company may repay any portion of the outstanding principal amount of the loans under the Ligand Note, plus accrued and previously unpaid interest thereon, by delivering a notice to Ligand (the “Additional Repayment Notice”), specifying the amount that the Company wishes to repay (the “Additional Payment Amount”). Ligand will have five days to elect to receive the Additional Payment Amount in cash, shares of the Company’s common stock or a combination of cash and shares of the Company’s common stock. If Ligand does not make an election within such five-day period, the form of the Additional Payment Amount will be at the Company’s sole election and discretion, subject to the number of shares of common stock being reduced to the extent that the issuance of shares would increase Ligand’s beneficial ownership of the Company’s common stock to greater than 49.9%. To the extent that any portion of an Additional Payment Amount will be paid in the form of shares of the Company’s common stock, the number of shares issuable will be equal to the quotient obtained by dividing the portion of the Additional Payment Amount that will be paid in shares by the lesser of (1) (a) if the Company delivers the Additional Repayment Notice within 180 days of the closing of the Next Financing, the Financing Price, or (b) if the Company delivers the Additional Repayment Notice 180 days or more after the closing of the Next Financing, the volume weighted average closing price of the Company’s common stock for the 30 days prior to the date the Company delivers the Additional Repayment Notice, and (2) $8.00 (subject to adjustment for stock dividends, splits, combinations or similar transactions). Each $1.00 of any Additional Repayment Amount will reduce the amount of accrued and unpaid interest and then unpaid principal amount under the Ligand Note by $0.50. Additionally, pursuant to the Loan and Security Agreement, Ligand has agreed that it will not, until January 23, 2017, sell or otherwise transfer or dispose of any of the Company’s securities, including shares issuable upon conversion of the Ligand Note. Following the Maturity Date, Ligand may demand repayment of the loans under the Ligand Note in full. If (1) the Ligand Note is not repaid in full prior to the Maturity Date and Ligand demands repayment, or (2) the Company wishes to repay the full amount owed under the Ligand Note prior to the Maturity Date, the Company will be obligated to repay to Ligand an amount equal to 200% of the aggregate of the outstanding principal amount of the loans under the Ligand Note and of all accrued and unpaid interest thereon, or the Remaining Balance. In either case, the Company may, at its sole election and discretion, elect to pay the Remaining Balance solely in cash. If the Company does not elect to repay the Remaining Balance in cash, the form of payment and mix of cash and shares of the Company’s common stock will be at Ligand’s sole election and discretion. To the extent that any portion of the Remaining Balance will be paid in the form of shares of the Company’s common stock, the number of shares issuable will be equal to the quotient obtained by dividing the portion of the Remaining Balance that will be paid in shares by the lesser of (1) the volume weighted average closing price of the Company’s common stock for the 30 days prior to the date of Ligand’s demand for repayment or the date of the Company’s prepayment of the Remaining Balance in full, and (2) $8.00 (subject to adjustment for stock dividends, splits, combinations or similar transactions). In connection with the Loan and Security Agreement, the Company also granted Ligand a continuing security interest in all of its right, title and interest in and to its assets as collateral for the full, prompt, complete and final payment and performance when due of all obligations under the Loan and Security Agreement and the Ligand Note. During the year ended December 31, 2016, the Company recorded $105,551 of interest expense, $1,788,088 of amortization of debt discount, offset with income of $1,064,170 related to the change in the fair value of the debt conversion feature liability. During the year ended December 31, 2015, the Company recorded $125,000 of interest expense, $887,426 of amortization of debt discount and $980,434 as other expense related to increases in the fair value of the debt conversion feature liability.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Stockholders' Equity (Deficit)	7. Stockholders’ Equity (Deficit) Preferred Stock The Company is authorized to issue up to 10,000,000 shares of $0.00001 par value preferred stock, with no shares of preferred stock outstanding as of December 31, 2016 and 2015. The Board of Directors is authorized to designate the terms and conditions of any preferred stock the company issues without further action by the common stockholders. Common Stock The Company is authorized to issue up to 300,000,000 shares of common stock, $0.00001 par value per share. In February 2014, the Company entered into a stock purchase agreement with one of its founders. The agreement provided for the purchase of 1,000,000 shares of the Company’s common stock at a price per share of $0.01 in exchange for future services to be rendered to the Company as measured by certain performance criteria. The shares were subject to a repurchase option and were to vest in two tranches of 500,000 shares each, upon achievement of the performance target or upon a triggering event as defined. The Company determined that the fair value of the unrecognized expense was $168,000 at February 20, 2014, the grant date. In May 2015, the Company repurchased 633,810 of these shares at a purchase price of $0.00001 per share. In connection with the repurchase, the Company entered into an amendment to the stock purchase agreement to provide that the remaining 366,190 shares will continue to vest in two tranches of 183,095 shares each, upon achievement of the performance target or upon a triggering event as defined. The pro rata grant date fair value of the unrecognized expense is $61,556. In October 2015, a triggering event became probable of occurrence and was deemed achieved in October 2016; therefore, the Company recorded $30,778 of stock-based compensation expense through December 31, 2016, of which $12,371 and $18,407 was recorded as expense during the years ended December 31, 2016 and 2015, respectively. The Company will continue to reassess at each reporting period whether it is probable that the performance target will be met, and if and when it is deemed probable, the Company will begin to record compensation expense using the fair value to determine stock-based compensation expense in its financial statements over the period the Company estimates the performance target will actually be met. On May 4, 2015, the Company completed its IPO pursuant to a registration statement on Form S-1 (File No. 333-197182), which was declared effective by the SEC on April 28, 2015, and a registration statement on Form S-1MEF (File No. 333-203702) filed pursuant to Rule 462(b) of the Securities Act. In the IPO, the Company sold 3,000,000 shares of its common stock at an initial public offering price of $8.00 per share. The underwriters for the IPO had 30 days to exercise an over-allotment option to purchase up to an additional 450,000 shares at the initial public offering price, less the underwriting discount. Upon the closing of the IPO, on May 4, 2015, the Company raised a total of $19,100,500 in net proceeds after deducting underwriting discounts, commissions and other offering expenses of $4,899,500. These costs have been recorded as a reduction of the proceeds received in arriving at the amount to be recorded in additional paid-in capital upon completion of the IPO. On May 4, 2015, prior to the completion of the IPO, the Company repurchased an aggregate of 3,802,859 shares of its common stock from its stockholders at a price of $0.00001 per share for an aggregate purchase price of $38. Pursuant to the Master License Agreement, upon the closing of the IPO, on May 4, 2015, the Company issued an aggregate of 3,427,859 shares of its common stock to Ligand and Metabasis Therapeutics, Inc., a wholly-owned subsidiary of Ligand (“Metabasis”). On April 28, 2015, the date of the execution and delivery of the underwriting agreement for the IPO, the Company granted stock options to purchase an aggregate of 83,144 shares of the Company’s common stock to the non-employee directors of the Company. Upon the closing of the IPO in May 2015, the Company (1) converted $27,422,872 of accrued license fees as of May 4, 2015 into 3,427,859 shares of the Company’s common stock pursuant to the Master License Agreement; (2) incurred a non-cash interest charge of $4,421,338 at the time of conversion of the accrued license fees, relating to the difference between the carrying amounts of the $24,826,374 of accrued license fees and the fair market value of the shares issued in the IPO; (3) converted $310,350 of the Company’s convertible notes payable plus interest of $24,276 as of May 4, 2015 into 57,046 shares of the Company’s common stock; (4) incurred a beneficial conversion charge of $121,786; and (5) issued an aggregate of 422,879 shares of the Company’s common stock and granted options to purchase an aggregate of 206,000 shares of the Company’s common stock to its employees, directors and a consultant of the Company pursuant to employment agreements, offer letters and a consulting agreement. On May 26, 2015, the underwriters for the IPO exercised their full over-allotment option to purchase an additional 450,000 shares of the Company’s common stock at $8.00 per share, less the underwriting discount. On May 28, 2015, the Company sold the 450,000 shares to the underwriters pursuant to the over-allotment option and received additional net proceeds of $3,225,866, after deducting underwriting discounts, commissions and other offering expenses of $374,134. Upon the closing of the over-allotment option, pursuant to the Master License Agreement, on May 28, 2015, the Company issued an additional aggregate of 228,105 shares of its common stock to Ligand and Metabasis. On April 13, 2016, the Company completed the Offering pursuant to a registration statement on Form S-1 (File No. 333-208182) that was declared effective on April 7, 2016, and a registration statement on Form S-1MEF (File No. 333-210650) filed pursuant to Rule 462(b) of the Securities Act. In the Offering, the Company sold 7,500,000 shares of its common stock and warrants to purchase up to 7,500,000 shares of its common stock at a public offering price of $1.25 per share of common stock and related warrant. The warrants have an exercise price of $1.50 per share of common stock, were immediately exercisable upon issuance and will expire on April 13, 2021. The Company granted the underwriters for the Offering a 45-day option to purchase up to an additional 1,125,000 shares of its common stock and/or warrants to purchase up to an additional 1,125,000 shares of its common stock to cover over-allotments, if any. Ligand, a related party to the Company, purchased 560,000 shares of the Company’s common stock and warrants to purchase up to 560,000 shares of Company’s common stock in the Offering. On April 13, 2016, the underwriters partially exercised the over-allotment option for warrants to purchase an additional 1,125,000 shares of the Company’s common stock at a public offering price of $0.01 per warrant. Upon the closing of the Offering on April 13, 2016, the Company received net proceeds of $7,754,286, after deducting underwriting discounts, commissions and other offering expenses of $1,631,964. On April 13, 2016, pursuant to the terms of the Loan and Security Agreement , the Company issued the Ligand Shares and the Ligand Warrant to Ligand. Th beneficial ownership of the Company’s common stock to greater than 49.9%) The Ligand Shares and the Ligand Warrant were issued to Ligand as a repayment of $1,200,000 of the Company’s obligation under the Ligand Note On April 27, 2016, the underwriters for the Offering exercised their over-allotment option to purchase 1,125,000 shares of the Company’s common stock at a public offering price of $1.24 per share. On April 29, 2016, the Company sold the shares to the underwriters pursuant to the over-allotment option and received additional On June 20, 2016, the Company entered into the Distribution Agreement with Maxim pursuant to which the Company may offer and sell, from time to time, through Maxim up to 3,748,726 shares of its common stock. Any shares of common stock offered and sold in the Maxim Offering will be issued pursuant to the Company’s registration statement on Form S-3 (File No. 333-212134) filed with the SEC on June 20, 2016 and the prospectus relating to the Maxim Offering that forms a part of the registration statement on Form S-3. The registration statement on Form S-3 was declared effective by the SEC on July 26, 2016. The number of shares of the Company’s common stock eligible for sale under the Distribution Agreement will be subject to the limitations of General Instruction I.B.6 of Form S-3. During the year ended December 31, 2016, the Company sold 778,849 shares of its common stock under the Distribution Agreement, resulting in net proceeds to the Company of $956,518, after deducting the sales agent’s commission. On August 24, 2016, the Company entered into the Purchase Agreement, pursuant to which Aspire Capital is committed to purchase up to an aggregate of $12.5 million of shares of the Company’s common stock over the 30-month term of the Purchase Agreement. Upon execution of the Purchase Agreement, the Company issued and sold 333,333 of the Initial Shares at a price per share of $1.50, for an aggregate purchase price of $500,000 440,278, which has been recorded as deferred financing costs and is included within other assets in the accompanying balance sheet as of December 31, 2016. The deferred financing costs were proratably charged to additional paid-in-capital for the Initial Shares, with the remainder of the costs being amortized over the term of the Purchase Agreement as there is no guarantee that additional shares will be sold under the Purchase Agreement. Pursuant to the terms of the Purchase Agreement, the Company may, from time to time and subject to certain limitations, direct Aspire Capital to purchase shares of the Company’s common stock using pricing formulas based on average prevailing market prices around the time of each sale. Additionally, the Company and Aspire may not effect any sales of shares of the Company's common stock under the Purchase Agreement during the continuance of an event of default or on any trading day that the closing sale price of its common stock is less than $0.40 per share (subject to adjustment for stock dividends, splits, combinations or similar transactions or events). During the year ended December 31, 2016, 150,000 shares were issued pursuant to the Purchase Agreement resulting in net proceeds to the Company of $173,250, in addition to the Initial Shares and the Commitment Shares. During the year ended December 31, 2016 and 2015, and in accordance with the Company’s 2014 Employee Stock Purchase Plan (the “ESPP”), the Company issued an aggregate of 21,616 and 5,711 shares of its common stock to certain employees, respectively.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	8. Stock-Based Compensation In connection with the IPO, the Company’s 2014 Equity Incentive Plan (the “2014 Plan”) and the ESPP became effective on April 28, 2015, the date of the execution and delivery of the underwriting agreement for the IPO. A total of 1,527,770 shares of the Company’s common stock were initially reserved for issuance under the 2014 Plan, and 458,331 shares of the Company’s common stock were initially reserved for issuance under the ESPP. On January 1, 2016, in accordance with the terms of the 2014 Plan, an additional 338,930 shares of the Company’s common stock were added to the number of shares reserved for issuance under the 2014 Plan and, in accordance with the terms of the ESPP, an additional 96,837 shares of the Company’s common stock were added to the number of shares reserved for issuance under the ESPP. The Company generally uses the straight-line or graded vesting method to allocate compensation cost to reporting periods over each optionee’s requisite service period, which is generally the vesting period, and estimates the fair value of stock-based awards or restricted stock units to employees and directors using the Black-Scholes option-valuation model. For options with a graded vesting schedule, the Company uses the graded vesting schedule to allocate compensation cost to reporting periods. The Black-Scholes model requires the input of subjective assumptions, including volatility, the expected term and the fair value of the underlying common stock on the date of grant, among other inputs. Stock options granted to non-employees are accounted for using the fair value approach. Stock options granted to non-employees are subject to periodic revaluation over their vesting terms. 2014 Plan. The 2014 Plan provides that the compensation committee of the Company’s Board of Directors (the “Compensation Committee”) may grant or issue stock options, stock appreciation rights, restricted shares, restricted stock units and unrestricted shares, deferred share units, performance and cash-settled awards and dividend equivalent rights to participants under the 2014 Plan. Initially, a total of 1,527,770 shares of the Company’s common stock were reserved for issuance pursuant to the 2014 Plan, which number is also the limit on shares of common stock available for awards of incentive stock options. The number of shares available for issuance under the 2014 Plan will, unless otherwise determined by the Company’s Board of Directors or the Compensation Committee, be automatically increased on January 1st of each year commencing on January 1, 2016 and ending on (and including) January 1, 2024, in an amount equal to 3.5% of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year. The shares of common stock deliverable pursuant to awards under the 2014 Plan are authorized but unissued shares of the Company’s common stock, or shares of the Company’s common stock that the Company otherwise holds in treasury or in trust. Any shares of the Company’s common stock underlying awards that are settled in cash or otherwise expire, or are forfeited, terminated or cancelled (including pursuant to an exchange program established by the Compensation Committee) prior to the issuance of stock will again be available for issuance under the 2014 Plan. In addition, shares of the Company’s common stock that are withheld (or not issued) in payment of the exercise price or taxes relating to an award, and shares of the Company’s common stock equal to the number surrendered in payment of any exercise price or withholding taxes relating to an award, will again be available for issuance under the 2014 Plan. ESPP. Initially, a total of 458,331 shares of the Company’s common stock were reserved for issuance pursuant to the ESPP. The number of shares available for issuance under the ESPP will, unless otherwise determined by the Company’s Board of Directors or the Compensation Committee, be automatically increased on January 1st of each year commencing on January 1, 2016 and ending on (and including) January 1, 2024, in an amount equal to 1% of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year. The shares of common stock available for purchase pursuant to the ESPP are authorized but unissued shares of the Company’s common stock, shares of the Company’s common stock that the Company otherwise holds in treasury or shares of the Company’s common stock that were purchased on the open market in arms’ length transactions in accordance with applicable securities laws. Shares of the Company’s common stock will be offered for purchase under the ESPP as determined by the Compensation Committee through a series of successive offerings that each have a term of 24 months and consist of four consecutive purchase periods of six months each. Prior to the commencement of any future offering under the ESPP, the Compensation Committee may determine that the current offering shall end, may commence a new offering on the first day after the end of such terminal purchase period (or any desired later date), and may decide that future offerings will consist of one or more consecutive purchase periods, each to be of such duration as determined by the Compensation Committee; however, no offering will exceed 27 months and no purchase period will exceed one year. Each employee of the Company who (1) is an employee on the first date of any offering under the ESPP, (2) is customarily scheduled to work for more than 20 hours per week and more than five months per calendar year, and (3) meets such other criteria as may be determined by the Compensation Committee (consistent with Section 423 of the Internal Revenue Code of 1986, as amended), is eligible to participate in the ESPP for each purchase period within such offering. The purchase price per share of the Company’s common stock under the ESPP may not be less than, and will initially be equal to, the lesser of: (1) 85% of the fair market value per share of the Company’s common stock on the first day of the offering, or (2) 85% of the fair market value per share of the Company’s common stock on the date the purchase right is exercised, which will be the last day of the applicable purchase period. During the years ended December 31, 2016 and 2015, the Company recognized the following stock-based compensation expense: Year Ended December 31, 2016 2015 Stock-based compensation expense by type of award: Stock options $ 921,556 $ 949,955 Restricted stock and restricted stock units 836,964 1,608,049 Employee stock purchase plan 35,807 43,444 Total stock-based compensation expense included in expenses $ 1,794,327 $ 2,601,448 Stock-based compensation expense by line item: Research and development expenses $ 537,008 $ 852,200 General and administrative expenses 1,257,319 1,749,248 Total stock-based compensation expense included in expenses $ 1,794,327 $ 2,601,448 The following table sets forth the Company’s unrecognized stock-based compensation expense, net of estimated forfeitures, by type of award and the weighted-average period over which that expense is expected to be recognized: As of December 31, 2016 Unrecognized Expense, Net of Estimated Forfeitures Weighted- average Recognition Period (in years) Type of award: Stock options $ 1,042,226 2.42 Restricted stock and restricted stock units $ 1,165,141 1.71 The following table is a summary of restricted shares granted during the year ended December 31, 2016: Shares Weighted- Average Grant Date Fair Value Unvested at December 31, 2015 667,963 $ 3.73 Granted - $ - Vested (291,313 ) $ 2.89 Forfeited (69,554 ) $ 6.37 Repurchased - $ - Unvested at December 31, 2016 307,096 $ 3.93 The following table summarizes restricted stock units activity during the year ended December 31, 2016: Shares Weighted- Average Grant Date Value Unvested at December 31, 2015 75,750 $ 8.27 Granted 40,000 $ 1.19 Vested (28,937 ) $ 5.83 Forfeited (6,188 ) $ 7.25 Repurchased — $ — Unvested December 31, 2016 80,625 $ 5.72 The following table summarizes stock option activity during the year ended December 31, 2016: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Options outstanding at December 31, 2015 365,394 $ 8.48 — Granted 620,818 $ 2.01 — Exercised — $ — — Cancelled (102,375 ) $ 5.55 — Options outstanding at December 31, 2016 883,837 $ 4.28 8.87 Options exercisable at December 31, 2016 301,824 $ 5.72 8.40 Compensation expense for stock options granted to employees is based on the estimated grant date fair value and is recognized ratably over the vesting period of the applicable option. The estimated per share weighted average fair value of stock options granted to employees during the year ended December 31, 2016 was $1.40. The options outstanding and exercisable at December 31, 2016 had no intrinsic value in the aggregate. As stock-based compensation expense recognized is based on options ultimately expected to vest, the fair value of each employee option grant during the year ended December 31, 2016 was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: Year Ended December 31, 2016 Expected volatility 82.6 % Expected term (in years) 5.90 Risk-free interest rate 1.59 % Expected dividend yield 0 % Expected Volatility. The expected volatility rate used to value stock option grants is based on volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the pharmaceutical and biotechnology industry in a similar stage of development to the Company. Expected Term . The Company elected to utilize the “simplified” method for “plain vanilla” options to value stock option grants. Under this approach, the weighted-average expected life is presumed to be the average of the vesting term and the contractual term of the option. Risk-free Interest Rate . The risk-free interest rate assumption was based on zero-coupon U.S. Treasury instruments that had terms consistent with the expected term of the Company’s stock option grants. Expected Dividend Yield . The Company has never declared or paid any cash dividends and does not presently plan to pay cash dividends in the foreseeable future. Forfeitures are accounted for as actual forfeitures occur. Since the Company had a net operating loss carryforward as of December 31, 2016, no excess tax benefits for the tax deductions related to stock-based awards were recognized in the Statements of Operations. Common Stock Reserved for Future Issuance Common stock reserved for future issuance as of December 31, 2016 and 2015 is as follows: Common Stock Reserved for Future Issuance December 31, 2016 2015 Common stock warrants 9,667,500 82,500 Restricted stock units 80,625 75,750 Common stock options 883,837 365,394 Available for grant under the 2014 Plan 631,136 773,629 Available for issuance under Employee Stock Purchase Plan 527,841 452,620 Shares issuable upon conversion of Ligand debt 3,519,753 670,902 15,310,692 2,420,795

Warrants

Warrants	12 Months Ended
	Dec. 31, 2016
Warrants And Rights Note Disclosure [Abstract]
Warrants	9. Warrants Upon the closing of the IPO, on May 4, 2015, the Company issued to the representative of the underwriters as additional compensation a warrant to purchase the aggregate of 82,500 shares of the Company’s common stock. The warrant is exercisable for cash or on a cashless basis at a per share exercise price equal to $10.00 commencing on April 28, 2016, one year following the date of the prospectus filed with the SEC relating to the IPO, and expiring on April 28, 2020. In addition, the warrant provides for registration rights upon request, under certain circumstances. The piggyback registration right provided in connection with the warrant will terminate on April 28, 2022. On February 14, 2017, the Company filed a Registration Statement on Form S-3 under the Securities Act covering the resale of the 82,500 shares of the Company’s common stock issuable upon exercise of the warrant. On April 13, 2016, pursuant to the Offering, the Company sold 7,500,000 shares of its common stock and warrants to purchase up to 7,500,000 shares of its common stock at a public offering price of $1.25 per share of common stock and related warrant. The warrants have an exercise price of $1.50 per share of common stock, were immediately exercisable upon issuance and will expire on April 13, 2021. Additionally, on April 13, 2016, the underwriters for the Offering partially exercised the over-allotment option for warrants to purchase an additional 1,125,000 shares of the Company’s common stock at a public offering price of $0.01 per warrant to purchase a share of common stock. On April 13, 2016, pursuant to the terms of the Loan and Security Agreement , the Company issued to Ligand the Ligand Warrant to purchase up to 960,000 shares of the Company’s common stock. beneficial ownership of the Company’s common stock to greater than 49.9%) The Ligand Warrant was issued to Ligand as a part of the repayment of $1,200,000 of the Company’s obligation under the Ligand Note

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes The reconciliations of the U.S. federal statutory tax rate to the effective income tax rate for the years ended December 31, 2016 and 2015 are as follows: December 31, 2016 2015 Tax provision at U.S. Federal statutory rates 34 % 34 % State income taxes net of federal benefit 3 % 8 % Non-deductible permanent items (7 )% (2 )% Stock options — — Other — — Change in valuation allowance (30 )% (40 )% Effective income tax rate — — Deferred income taxes reflect the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred taxes as of December 31, 2016 and 2015 are as follows: December 31, 2016 2015 Deferred tax assets: Accrued liabilities $ 59,333 $ 48,982 Intangible assets 16,388,591 14,009,497 Net operating loss carryforwards 4,558,964 2,430,249 Share-based compensation 1,289,957 986,534 Share conversion feature - 243,759 Other 3,017 3,510 Total deferred tax assets 22,299,862 17,722,531 Valuation Allowance (22,115,992 ) (17,722,531 ) Total deferred tax assets, net of allowance $ 183,870 $ — Deferred tax liabilities: Debt conversion feature $ (183,870 ) $ — Total deferred tax liabilities: $ (183,870 ) $ — Net deferred tax assets (liabilities): $ — $ — A valuation allowance of $22,115,992 and $17,722,531 at December 31, 2016 and December 31, 2015, respectively, has been recorded to offset net deferred tax assets, as the Company is unable to conclude that it is more likely than not that such deferred tax assets will be realized. At December 31, 2016, the Company had federal and state net operating loss carryforwards of approximately $11,468,000 and $11,307,000, respectively. The federal and state net operating loss carryforwards will begin to expire in 2032. The Company’s ability to utilize its federal net operating loss carryforwards may be limited under Section 382 of the Internal Revenue Code of 1986, as amended (the “Code”). Specifically, this limitation may arise in the event of an “ownership change,” which is defined by Section 382 of the Code as a cumulative change in ownership of the Company of more than 50% within a three-year period. If the Company undergoes one or more ownership changes in connection with any future transactions in its stock, the Company’s ability to utilize net operating loss carryforwards to offset federal taxable income, if any, could potentially result in increased future tax liability to the Company. An ownership change under Section 382 of the Code occurred during the year ended December 31, 2015 in connection with the Company’s initial public offering. A portion of the net operating loss carryforwards are subject to an annual limitation. The Company is subject to U.S. federal income tax as well as income tax in various state jurisdictions. The Company is currently open to audit under the statute of limitations by the Internal Revenue Service and various state agencies for the years ended December 31, 2012 through December 31, 2016. The differences between the Company’s effective income tax rate and the statutory federal rate for the year ended December 31, 2016 and the year ended December 31, 2015 relate primarily to losses incurred for which no tax benefit was recognized, due to the uncertainty of realization. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the period in which those temporary differences become deductible. The Company considers projected future taxable income and tax planning strategies in making this assessment. At each of December 31, 2016 and December 31, 2015, the Company provided a full valuation allowance against its deferred tax assets due to uncertainty surrounding the realization of those assets as a result of historical taxable net losses. The Company has reviewed its operations and has not identified any material uncertain tax positions. As a result, there is no liability for uncertain tax positions in the income tax provision as of December 31, 2016 or December 31, 2015.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Related Party Transactions	11. Related Party Transactions In May 2014, the Company entered into the Master License Agreement with Ligand, pursuant to which, among other things, Ligand granted the Company an exclusive worldwide license to certain clinical and preclinical programs. See Note 4 for more information related to this agreement. In connection with entering into the Master License Agreement, the Company also entered into a Loan and Security Agreement (see Note 6), a Management Rights Letter (see Note 4) and a Registration Rights Agreement (see Note 4 ). As Ligand owns 35.0% of the Company’s outstanding shares as of December 31, 2016, the Company considers Ligand to be a related party.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. Commitments and Contingencies On July 7, 2015, the Company entered into a Sublease (the “Sublease”) for approximately 7,049 rentable square feet of space located at 12340 El Camino Real, Suite 250, San Diego, California 92130. Monthly base rent payments due under the Sublease are $19,737, subject to annual increases of 3.0% during the term of the Sublease. Under the Sublease, the Company is responsible for certain charges for common area maintenance and other costs pursuant to the Sublease, and the Sublease provides for abatement of rent during certain periods and escalating rent payments throughout the term of the Sublease. Rent expense is being recorded on a straight line basis over the life of the Sublease and the difference between the rent expense and rent paid is being recorded as deferred rent. Rent expense was $253,316 and $142,288 for the years ended December 31, 2016 and 2015, respectively. Future minimum payments pursuant to the Sublease are as follows: Year Ending December 31: 2017 227,282 2018 190,337 Total minimum lease payments $ 417,619

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events The Company evaluated subsequent events through March 21, 2017, the date of the filing of this Annual Report on Form 10-K with the SEC, to ensure that this filing includes appropriate disclosure of events both recognized in the financial statements as of December 31, 2016, and events which occurred subsequent to December 31, 2016 but were not recognized in the financial statements. The Company has determined that there were no subsequent events which required recognition, adjustment to or disclosure in the financial statements, except as follows: Subsequent to December 31, 2016, the Company sold an aggregate of 1,815,379 shares of its common stock pursuant to the Distribution Agreement with Maxim and the Purchase Agreement with Aspire Capital, resulting in additional net proceeds to the Company of $2,539,543, after deducting the sales agents’ commissions. On February 8, 2017, the Company entered into a Stock Purchase Agreement (the “SPA”) with PoC Capital, LLC, a California limited liability company (“PoC”), pursuant to which, among other things, the Company sold to PoC, and PoC purchased from the Company, 1,286,173 shares (the “Shares”) of common stock of the Company for an aggregate issue price of $1,800,000. The proceeds from the sale of the Shares are reserved exclusively to fund certain of the Company’s clinical trials pursuant to a master services agreement with a clinical research organization. Pursuant to the SPA, the Company also agreed to prepare and file one or more registration statements with the Securities and Exchange Commission (the “SEC”) for the purpose of registering the Shares for resale. Under the SPA, the Company agreed to file a registration statement with the SEC registering all of the Shares for resale by no later than February 23, 2017. On February 14, 2017, the Company filed a Registration Statement on Form S-3 under the Securities Act covering the resale of the full amount of the Registrable Securities, the shares of Common Stock issuable upon exercise of the warrant issued to the representative of the underwriters of the IPO and the shares issued to PoC pursuant to the SPA.

Organization, Liquidity and M20

Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
The Company	The Company Viking Therapeutics, Inc., a Delaware corporation (the “Company”), is a clinical-stage biopharmaceutical company focused on the development of novel therapies for metabolic and endocrine disorders. The Company was incorporated under the laws of the State of Delaware on September 24, 2012 and its principal executive offices are located in San Diego, CA.
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying financial statements. Significant estimates made in preparing these financial statements relate to determining the fair value of the debt conversion feature liability and accounting for certain commitments. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with maturities of three months or less from the date of purchase to be cash equivalents.
Investments Available-for-Sale	Investments Available-for-Sale Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. The amortization of premiums and accretion of discounts is included in interest income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income (expense). The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments, which potentially subject the Company to concentration of credit risk, consist primarily of cash and cash equivalents and marketable securities. The Company maintains deposits in federally insured depository institutions in excess of federally insured limits. Management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. Additionally, the Company has established guidelines regarding approved investments and maturities of investments, which are designed to maintain safety and liquidity.
Liquidity and Management's Plan	Liquidity and Management’s Plan In accordance with Accounting Standards Update In April 2016, the Company completed an underwritten public offering of its common stock and warrants to purchase shares of its common stock (the “Offering”) pursuant to a registration statement on Form S-1 (File No. 333-208182). In the Offering, the Company sold 8,625,000 shares of its common stock and warrants to purchase up to 8,625,000 shares of its common stock at a public offering price of $1.25 per share of common stock and related warrant. The warrants have an exercise price of $1.50 per share of common stock, were immediately exercisable upon issuance and will expire on April 13, 2021. Upon the closing of the Offering in April 2016, the Company received net proceeds of $9,037,686, after deducting underwriting discounts, commissions and other offering expenses of $1,743,564. On June 20, 2016, the Company entered into an Equity Distribution Agreement (the “Distribution Agreement”) with Maxim Group LLC, as sales agent (“Maxim”), pursuant to which the Company may offer and sell, from time to time, through Maxim (the “Maxim Offering”), up to 3,748,726 shares of its common stock. During the year ended December 31, 2016, the Company sold 778,849 shares of its common stock under the Distribution Agreement resulting in net proceeds to the Company of $956,518, after deducting the sales agent’s commission. On August 24, 2016, the Company entered into a Common Stock Purchase Agreement (the “Purchase Agreement”) with Aspire Capital Fund, LLC (“Aspire Capital”), pursuant to which Aspire Capital committed to purchase up to an aggregate of $12.5 million of shares of the Company’s common stock over the 30-month term of the Purchase Agreement. Upon execution of the Purchase Agreement, the Company issued and sold to Aspire Capital under the Purchase Agreement 333,333 shares of common stock (the “Initial Shares”) at a price per share of $1.50, for an aggregate purchase price of $500,000. Concurrently with the execution of the Purchase Agreement, and as consideration for Aspire Capital entering into the Purchase Agreement, the Company issued to Aspire Capital 336,116 shares of common stock as a commitment fee (the “Commitment Shares”). Pursuant to the terms of the Purchase Agreement, the Company may, from time to time and subject to certain limitations, direct Aspire Capital to purchase shares of the Company’s common stock using pricing formulas based on average prevailing market prices around the time of each sale. During the year ended December 31, 2016, 150,000 shares were issued pursuant to the Purchase Agreement resulting in aggregate gross proceeds of $173,250, in addition to the Initial Shares and the Commitment Shares. Although it is difficult to predict the Company’s liquidity requirements, as of December 31, 2016, and based upon the Company’s current operating plan, the Company does not believe that it will have sufficient cash to meet its projected operating requirements for at least the next 12 months following the issuance of the financial statements unless it raises additional capital. As of December 31, 2016, the Company had an accumulated deficit of $60,277,267. These losses have resulted principally from research and development costs incurred in connection with acquiring the exclusive worldwide rights to the portfolio of five drug candidates from Ligand Pharmaceuticals Incorporated (“Ligand”) and the related non-cash interest expense recorded for increases in the deemed fair market value for the license fees payable to Ligand, research and development expenses related to the manufacturing of clinical drug product and clinical development of VK5211, VK2809 and VK0214, consulting fees and general and administrative expenses. The Company anticipates that it will continue to incur net losses for the foreseeable future as it continues the development of its clinical drug candidates and preclinical programs and incurs additional costs associated with being a public company.
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs represent legal, accounting and other direct costs related to the Company’s efforts to raise capital through a public or private sale of the Company’s common stock. Costs related to the public sale of the Company’s common stock are deferred until the completion of the applicable offering, at which time such costs are reclassified to additional paid-in-capital as a reduction of the proceeds. Costs related to the private sale of the Company’s common stock are deferred until the completion of the applicable offering, at which time such costs are amortized over the term of the applicable purchase agreement.
Revenue Recognition	Revenue Recognition The Company has not recorded any revenues since its inception. However, in the future, the Company may enter into collaborative research and licensing agreements, under which the Company could be eligible for payments made in the form of upfront license fees, research funding, cost reimbursement, contingent event-based payments and royalties. Revenue from upfront, nonrefundable license fees is recognized over the period that any related services are provided by the Company. Amounts received for research funding are recognized as revenue as the research services that are the subject of such funding are performed. Revenue derived from reimbursement of research and development costs in transactions where the Company acts as a principal are recorded as revenue for the gross amount of the reimbursement, and the costs associated with these reimbursements are reflected as a component of research and development expense in the statements of operations. The Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) Topic 605-28, Revenue Recognition – Milestone Method (“ASC 605-28”), established the milestone method as an acceptable method of revenue recognition for certain contingent event-based payments under research and development arrangements. Under the milestone method, a payment that is contingent upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved. A milestone is an event (1) that can be achieved based in whole or in part on either the Company’s performance or on the occurrence of a specific outcome resulting from the Company’s performance, (2) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved, and (3) that would result in additional payments being due to the Company. The determination that a milestone is substantive is subject to management’s judgment and is made at the inception of the arrangement. Milestones are considered substantive when the consideration earned from the achievement of the milestone is (a) commensurate with either the Company’s performance to achieve the milestone or the enhancement of value of the item delivered as a result of a specific outcome resulting from the Company’s performance to achieve the milestone, (b) relates solely to past performance, and (c) is reasonable relative to all deliverables and payment terms in the arrangement. Other contingent event-based payments received for which payment is either contingent solely upon the passage of time or the results of a collaborative partner’s performance are not considered milestones under ASC 605-28. In accordance with ASC Topic 605-25, Revenue Recognition – Multiple-Element Arrangements
Research and Development Expenses	Research and Development Expenses All costs of research and development are expensed in the period incurred. Research and development costs primarily consist of fees paid to contract research organizations (“CROs”) and clinical trial sites, employee and consultant related expenses, which include salaries, benefits and stock-based compensation for research and development personnel, external research and development expenses incurred pursuant to agreements with third-party manufacturing organizations, facilities costs, travel costs, dues and subscriptions, depreciation and materials used in preclinical studies, clinical trials and research and development. The Company estimates its preclinical study and clinical trial expenses based on the services it received pursuant to contracts with research institutions and CROs that conduct and manage preclinical studies and clinical trials on the Company’s behalf. Clinical trial-related contracts vary significantly in length, and may be for a fixed amount, based on milestones or deliverables, a variable amount based on actual costs incurred, capped at a certain limit, or for a combination of these elements. The Company accrues service fees based on work performed, which relies on estimates of total costs incurred based on milestones achieved, patient enrollment and other events. The majority of the Company’s service providers invoice the Company in arrears, and to the extent that amounts invoiced differ from its estimates of expenses incurred, the Company accrues for additional costs. The financial terms of these agreements vary from contract to contract and may result in uneven expenses and payment flows. Preclinical study and clinical trial expenses include: • fees paid to CROs, consultants and laboratories in connection with preclinical studies; • fees paid to CROs, clinical trial sites, investigators and consultants in connection with clinical trials; and • fees paid to contract manufacturers and service providers in connection with the production, testing and packaging of active pharmaceutical ingredients and drug materials for preclinical studies and clinical trials. Payments under some of these agreements depend on factors such as the milestones accomplished, including enrollment of certain numbers of patients, site initiation and the completion of clinical trial milestones. To date, the Company has not experienced any events requiring it to make material adjustments to its accruals for service fees. If the Company does not identify costs that it has begun to incur or if it underestimates or overestimates the level of services performed or the costs of these services, its actual expenses could differ from its estimates which could materially affect its results of operations. Adjustments to the Company’s accruals are recorded as changes in estimates become evident. Furthermore, based on amounts invoiced to the Company by its service providers, the Company may also record payments made to those providers as prepaid expenses that will be recognized as expense in future periods as services are rendered. In May 2014, the Company entered into the Master License Agreement, pursuant to which it acquired certain rights to a number of research and development programs from Ligand. In doing so, the Company updated its policy on research and development to include the purchase of rights to intangible assets. In accordance with ASC Topic 730, Research and Development,
Patent Costs	Patent Costs Costs related to filing and pursuing patent applications are expensed as incurred to general and administrative expense, as recoverability of such expenditures is uncertain.
Stock-Based Compensation	Stock-Based Compensation The Company generally uses the straight-line or graded vesting method to allocate compensation cost to reporting periods over each optionee’s requisite service period, which is generally the vesting period, and estimates the fair value of stock-based awards or restricted stock units to employees and directors using the Black-Scholes option-valuation model. For options with a graded vesting schedule, the Company uses the graded vesting schedule to allocate compensation cost to reporting periods. The Black-Scholes model requires the input of subjective assumptions, including volatility, the expected term and the fair value of the underlying common stock on the date of grant, among other inputs. Stock options granted to non-employees are accounted for using the fair value approach. Stock options granted to non-employees are subject to periodic revaluation over their vesting terms. For restricted stock and restricted stock unit awards, the Company generally uses the straight-line or graded vesting method to allocate compensation cost to reporting periods over the holder’s requisite service period, which is generally the vesting period, and uses the fair value at grant date to value the awards. For restricted stock that vests upon the satisfaction of certain performance conditions, the Company recognizes stock-based compensation expense when it becomes probable that the performance conditions will be met. At the point that it becomes probable that the performance conditions will be met, the Company records a cumulative catch-up of the expense from the grant date to the current date, and the Company then amortizes the remainder of the expense over the remaining service period. Prior to the Company’s initial public offering of its common stock (the “IPO”), the Company accounted for stock-based compensation by measuring and recognizing compensation expense for all stock-based payments made to employees and directors based on estimated award date fair values, which estimates were highly complex and subjective in nature. The Company used the straight-line or graded vesting method to allocate compensation cost to reporting periods over each restricted award’s requisite service period, which was generally the vesting period, and estimated the fair value of restricted stock-based awards to employees and consultants using a Monte Carlo market approach simulation method and performed an allocation of value to common stock based on the estimated time to a liquidity event. In addition, the Company accounted for performance-based restricted stock awards to employees by determining the fair value of the restricted stock award at the date of issuance by using the Probability Weighted Expected Return Method (“PWERM”) and then assessing at each balance sheet date the probability of the performance criteria being met. If the probability of achieving the criteria was deemed less-than-probable, then no expense was recorded. At the point where the criteria were deemed probable of being met, the Company then began recording stock-based compensation with a cumulative catch-up expense in the period first recognized and then on a straight-line basis over the remaining period for which the performance criteria were expected to be completed.
Income Taxes	Income Taxes The Company accounts for its income taxes using the liability method whereby deferred tax assets and liabilities are determined based on temporary differences between the basis used for financial reporting and income tax reporting purposes. Deferred income taxes are provided based on the enacted tax rates in effect at the time such temporary differences are expected to reverse. A valuation allowance is provided for deferred tax assets if it is more likely than not that the Company will not realize those tax assets through future operations. ASC Topic 740-10, Income Taxes The Company’s policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense.
Net Loss per Common Share	Net Loss per Common Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, the Company currently does not have any deemed common share equivalents; therefore, its basic and diluted net loss per share calculations are the same. The following table presents the computation of basic and diluted net loss per common share: Year Ended December 31, 2016 2015 Historical net loss per share Numerator Net loss attributable to common stockholders $ (14,731,822 ) $ (23,403,988 ) Denominator Weighted-average common shares outstanding 16,767,235 8,514,155 Less: Weighted-average shares subject to repurchase (488,943 ) (2,158,286 ) Denominator for basic and diluted net loss per share 16,278,292 6,355,869 Basic and diluted net loss per share $ (0.90 ) $ (3.68 ) Potentially dilutive securities that are not included in the calculation of diluted net loss per share because their effect is anti-dilutive are as follows (in common equivalent shares): Year Ended December 31, 2016 2015 Common stock warrants 9,667,500 82,500 Restricted stock units 80,625 75,750 Common stock subject to repurchase 307,096 667,963 Common stock options 883,837 365,394 Shares issuable upon conversion of debt 3,519,753 670,902 14,458,811 1,862,509
Segments	Segments The Company operates in only one segment. Management uses cash flows as the primary measure to manage its business and does not segment its business for internal reporting or decision making purposes.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. The FASB has subsequently issued the following amendments to ASU No. 2014-09, which have the same effective date and transition date of January 1, 2018: • In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers • In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers • In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers • In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers • In December 2016, the FASB issued ASU No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which amends certain narrow aspects of the guidance issued in ASU No. 2014-09 including guidance related to the disclosure of remaining performance obligations and prior-period performance obligations, as well as other amendments to the guidance on loan guarantee fees, contract costs, refund liabilities, advertising costs and the clarification of certain examples. The Company will continue to evaluate the potential impact that these standards will have on its financial position and results of operations, although there is no current impact of this new guidance on its financial statements as the Company does not currently have any revenue generating arrangements. In February 2016, the FASB issued ASU No. 2016-02, Leases for the Company in the first quarter of fiscal year 2019 and early adoption is permitted. ASU 2016-02 is required to be applied with a modified retrospective approach and requires application of the new standard at the beginning of the earliest comparative period presented. The Company does not expect the adoption of ASU 2016-02 to have a material effect on its financial statements and related disclosures. In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-based Payment Accounting simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. Under this guidance, a company recognizes all excess tax benefits and tax deficiencies as income tax expense or benefit in the statement of operations. This change eliminates the notion of the additional paid-in capital pool and reduces the complexity in accounting for excess tax benefits and tax deficiencies. In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments The Company is evaluating the effect that ASU 2016-13 will have on its financial statements and related disclosures. In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments

Organization, Liquidity and M21

Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Computation of Basic and Diluted Net Loss per Common Share	The following table presents the computation of basic and diluted net loss per common share: Year Ended December 31, 2016 2015 Historical net loss per share Numerator Net loss attributable to common stockholders $ (14,731,822 ) $ (23,403,988 ) Denominator Weighted-average common shares outstanding 16,767,235 8,514,155 Less: Weighted-average shares subject to repurchase (488,943 ) (2,158,286 ) Denominator for basic and diluted net loss per share 16,278,292 6,355,869 Basic and diluted net loss per share $ (0.90 ) $ (3.68 )
Schedule of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss per Share	Potentially dilutive securities that are not included in the calculation of diluted net loss per share because their effect is anti-dilutive are as follows (in common equivalent shares): Year Ended December 31, 2016 2015 Common stock warrants 9,667,500 82,500 Restricted stock units 80,625 75,750 Common stock subject to repurchase 307,096 667,963 Common stock options 883,837 365,394 Shares issuable upon conversion of debt 3,519,753 670,902 14,458,811 1,862,509

Investments in Marketable Sec22

Investments in Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Summary of Investments Classified As Available-For-Sale Securities	Investments classified as available-for-sale as of December 31, 2016 consisted of the following: Amortized Cost Gross Unrealized Gains (1) Gross Unrealized Losses (1) Aggregate Estimated Fair Value Corporate debt securities (2) $ 10,081,950 $ — $ (6,892 ) $ 10,075,058 (1) Unrealized gains and losses on available-for-sale securities are included as a component of comprehensive loss. At December 31, 2016, there were 25 securities in an unrealized loss position. These unrealized losses were less than $1,000 individually and $7,000 in the aggregate. These securities have not been in a continuous unrealized loss position for more than 12 months. The Company does not intend to sell these investments and it is not more likely than not that the Company will be required to sell these investments before recovery of their amortized cost basis, which may be at maturity. The Company reviews its investments to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. ( 2 ) At December 31, 2016, none of these securities were classified as cash and cash equivalents on the Company’s balance sheet and none of these securities were scheduled to mature outside of one year. Investments classified as available-for-sale as of December 31, 2015 consisted of the following: Amortized Cost Gross Unrealized Gains (1) Gross Unrealized Losses (1) Aggregate Estimated Fair Value Certificates of deposit (2) $ 5,851,343 $ — $ — $ 5,851,343 Corporate debt securities (2) 7,491,526 — (7,370 ) 7,484,156 $ 13,342,869 $ — $ (7,370 ) $ 13,335,499 (1) Unrealized gains and losses on available-for-sale securities are included as a component of comprehensive loss. At December 31, 2015, there were 14 securities in an unrealized loss position. These unrealized losses were less than $2,000 individually and $8,000 in the aggregate. These securities have not been in a continuous unrealized loss position for more than 12 months. The Company does not intend to sell these investments and it is not more likely than not that the Company will be required to sell these investments before recovery of their amortized cost basis, which may be at maturity. The Company reviews its investments to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. (2) At December 31, 2015, none of these securities were classified as cash and cash equivalents on the Company’s balance sheet and none of these securities were scheduled to mature outside of one year.

Fair Value of Financial Instr23

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Summary of Fair Values of Financial Instruments	The fair values of the Company’s financial instruments are presented below: Fair Value Measurements at December 31, 2016 Total Level 1 Level 2 Level 3 Financial assets carried at fair value: Cash equivalents: Money market funds $ 2,519,322 $ 2,519,322 $ — $ — Short-term investments Corporate debt securities, available-for-sale 10,075,058 — 10,075,058 — Total financial assets $ 12,594,380 $ 2,519,322 $ 10,075,058 $ — Financial liabilities carried at fair value: Debt conversion feature - long-term $ 731,048 $ — $ — $ 731,048 Total financial liabilities $ 731,048 $ — $ — $ 731,048 Fair Value Measurements at December 31, 2015 Total Level 1 Level 2 Level 3 Financial assets carried at fair value: Cash equivalents: Money market funds $ 548,872 $ 548,872 $ — $ — Short-term investments Certificates of deposit 5,851,343 5,851,343 — — Corporate debt securities, available-for-sale 7,484,156 — 7,484,156 — Total financial assets $ 13,884,371 $ 6,400,215 $ 7,484,156 $ — Financial liabilities carried at fair value: Debt conversion feature - long-term $ 2,370,903 $ — $ — $ 2,370,903 Total financial liabilities $ 2,370,903 $ — $ — $ 2,370,903
Summary of Changes in Accrued License Fees and Debt Conversion Feature Liability Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs	The table below presents a summary of changes in the Company’s debt conversion feature liability measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the years ended December 31, 2016 and 2015: Year Ended December 31, 2016 2015 Debt conversion feature liability: Beginning balance $ 2,370,903 $ 1,449,211 Adjustments resulting from modification of debt (575,685 ) — Adjustments resulting from changes in fair value recognized in earnings (1,064,170 ) 1,043,478 Issuance of shares of common stock — (121,786 ) Ending balance $ 731,048 $ 2,370,903
Schedule of Valuation Techniques and Significant Unobservable Inputs Used to Determine Fair Value of Significant Level 3 Liabilities	The following table sets forth the Company’s valuation techniques and significant unobservable inputs used to determine fair value for significant Level 3 liabilities: Fair Value Significant Assets Liabilities Valuation Technique(s) Unobservable Input Range Debt conversion feature liability December 31, 2016 $ — $ 731,048 Black-Scholes-Merton option valuation model Volatility 61% Risk Free Rate 0.57% December 31, 2015 $ — $ 2,370,903 Discounted cash flow model Timing of the events 5/21/2016 Probabilities of Occurrence 100% Discount rate 37.5%

Convertible Notes Payable (Tabl

Convertible Notes Payable (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Schedule of Convertible Notes Payable	Convertible notes payable consisted of the following at: December 31, 2016 2015 Current maturities: Convertible note payable issued during 2014 to Ligand pursuant to the Master License Agreement with a 5% annual interest rate, due during 2016 (amended in January 2016 to a 2.5% annual interest rate with maturity extended to 2017) $ 1,955,139 $ — Conversion payoff value 1,990,032 Discount on notes payable, current (675,589 ) — Convertible notes payable, current portion (net of discount) $ 3,269,582 $ — Long-term maturities: Convertible note payable issued during 2014 to Ligand pursuant to the Master License Agreement with a 5% annual interest rate, due during 2016 (amended in January 2016 to a 2.5% annual interest rate with maturity extended to 2017) $ — $ 2,500,000 Discount on notes payable, long-term — (348,460 ) Convertible notes payable, long-term (net of discount) $ — $ 2,151,540

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Summary of Stock-based Compensation Expense Recognized	During the years ended December 31, 2016 and 2015, the Company recognized the following stock-based compensation expense: Year Ended December 31, 2016 2015 Stock-based compensation expense by type of award: Stock options $ 921,556 $ 949,955 Restricted stock and restricted stock units 836,964 1,608,049 Employee stock purchase plan 35,807 43,444 Total stock-based compensation expense included in expenses $ 1,794,327 $ 2,601,448 Stock-based compensation expense by line item: Research and development expenses $ 537,008 $ 852,200 General and administrative expenses 1,257,319 1,749,248 Total stock-based compensation expense included in expenses $ 1,794,327 $ 2,601,448
Schedule of Unrecognized Stock-based Compensation Expense, Net of Estimated Forfeitures, by Type of Award and Weighted-average Recognition Period	The following table sets forth the Company’s unrecognized stock-based compensation expense, net of estimated forfeitures, by type of award and the weighted-average period over which that expense is expected to be recognized: As of December 31, 2016 Unrecognized Expense, Net of Estimated Forfeitures Weighted- average Recognition Period (in years) Type of award: Stock options $ 1,042,226 2.42 Restricted stock and restricted stock units $ 1,165,141 1.71
Summary of Stock Option Activity	The following table summarizes stock option activity during the year ended December 31, 2016: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Options outstanding at December 31, 2015 365,394 $ 8.48 — Granted 620,818 $ 2.01 — Exercised — $ — — Cancelled (102,375 ) $ 5.55 — Options outstanding at December 31, 2016 883,837 $ 4.28 8.87 Options exercisable at December 31, 2016 301,824 $ 5.72 8.40
Schedule of Weighted Average Assumptions using Black-Scholes Option Pricing Model	the fair value of each employee option grant during the year ended December 31, 2016 was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: Year Ended December 31, 2016 Expected volatility 82.6 % Expected term (in years) 5.90 Risk-free interest rate 1.59 % Expected dividend yield 0 %
Common Stock Reserved For Future Issuance	Common stock reserved for future issuance as of December 31, 2016 and 2015 is as follows: Common Stock Reserved for Future Issuance December 31, 2016 2015 Common stock warrants 9,667,500 82,500 Restricted stock units 80,625 75,750 Common stock options 883,837 365,394 Available for grant under the 2014 Plan 631,136 773,629 Available for issuance under Employee Stock Purchase Plan 527,841 452,620 Shares issuable upon conversion of Ligand debt 3,519,753 670,902 15,310,692 2,420,795
Restricted shares [Member]
Summary of Shares Granted and Stock Activity	The following table is a summary of restricted shares granted during the year ended December 31, 2016: Shares Weighted- Average Grant Date Fair Value Unvested at December 31, 2015 667,963 $ 3.73 Granted - $ - Vested (291,313 ) $ 2.89 Forfeited (69,554 ) $ 6.37 Repurchased - $ - Unvested at December 31, 2016 307,096 $ 3.93
Restricted stock units [Member]
Summary of Shares Granted and Stock Activity	The following table summarizes restricted stock units activity during the year ended December 31, 2016: Shares Weighted- Average Grant Date Value Unvested at December 31, 2015 75,750 $ 8.27 Granted 40,000 $ 1.19 Vested (28,937 ) $ 5.83 Forfeited (6,188 ) $ 7.25 Repurchased — $ — Unvested December 31, 2016 80,625 $ 5.72

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Schedule of Reconciliations of the U.S. Federal Statutory Tax Rate to the Effective Income Tax Rate	The reconciliations of the U.S. federal statutory tax rate to the effective income tax rate for the years ended December 31, 2016 and 2015 are as follows: December 31, 2016 2015 Tax provision at U.S. Federal statutory rates 34 % 34 % State income taxes net of federal benefit 3 % 8 % Non-deductible permanent items (7 )% (2 )% Stock options — — Other — — Change in valuation allowance (30 )% (40 )% Effective income tax rate — —
Schedule of Significant Components of Company's Deferred Taxes	Significant components of the Company’s deferred taxes as of December 31, 2016 and 2015 are as follows: December 31, 2016 2015 Deferred tax assets: Accrued liabilities $ 59,333 $ 48,982 Intangible assets 16,388,591 14,009,497 Net operating loss carryforwards 4,558,964 2,430,249 Share-based compensation 1,289,957 986,534 Share conversion feature - 243,759 Other 3,017 3,510 Total deferred tax assets 22,299,862 17,722,531 Valuation Allowance (22,115,992 ) (17,722,531 ) Total deferred tax assets, net of allowance $ 183,870 $ — Deferred tax liabilities: Debt conversion feature $ (183,870 ) $ — Total deferred tax liabilities: $ (183,870 ) $ — Net deferred tax assets (liabilities): $ — $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Summary of Future Minimum Payments for Sublease	Future minimum payments pursuant to the Sublease are as follows: Year Ending December 31: 2017 227,282 2018 190,337 Total minimum lease payments $ 417,619

Organization, Liquidity and M28

Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies - Additional Information (Detail)	Aug. 24, 2016USD ($)$ / sharesshares	Jun. 20, 2016shares	Apr. 29, 2016USD ($)shares	Apr. 13, 2016USD ($)$ / sharesshares	Apr. 30, 2016USD ($)$ / sharesshares	Dec. 31, 2016USD ($)CandidateSegment$ / sharesshares	Dec. 31, 2015USD ($)shares
Organization And Summary Of Significant Accounting Policies [Line Items]
Date of incorporation						Sep. 24, 2012
State of Incorporation						Delaware
Highly liquid investments maturities						Three months or less
Common stock sold | shares			1,125,000	7,500,000	8,625,000
Warrants sold | shares				7,500,000	8,625,000
Common stock, price per share | $ / shares				$ 1.25	$ 1.25
Exercise price per share of common stock | $ / shares				$ 1.50	$ 1.50	$ 10
Warrants expiry date					Apr. 13, 2021	Apr. 13, 2021
Cash proceeds from common stock issuance | $			$ 1,283,400	$ 7,754,286	$ 9,037,686	$ 11,548,518	$ 25,392,500
Underwriting discounts, commissions and other offering expenses | $			$ 111,600	$ 1,631,964	$ 1,743,564
Accumulated deficit | $						$ (60,277,267)	$ (45,545,445)
Number of operating segment | Segment						1
Common Stock [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Common stock sold | shares							3,655,964
Maxim [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Cash proceeds from common stock issuance | $						$ 956,518
Maxim [Member] | Common Stock [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Common stock sold | shares						778,849
Maxim [Member] | Common Stock [Member] | Maximum [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Sale of common stock, shares | shares		3,748,726
Aspire Capital [Member] | Common Stock [Member] | Stock Purchase Agreement [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Common stock sold | shares	333,333					150,000
Common stock, price per share | $ / shares	$ 1.50
Cash proceeds from common stock issuance | $						$ 173,250
Common stock sold aggregate purchase price | $	$ 500,000
Common stock purchase agreement term	30 months
Common stock issued as consideration for commitment fee | shares	336,116
Gross proceeds from common stock issuance | $						173,250
Aspire Capital [Member] | Common Stock [Member] | Maximum [Member] | Stock Purchase Agreement [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Common stock sold aggregate purchase price | $	$ 12,500,000
Ligand [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Common stock sold | shares				560,000
Warrants sold | shares				560,000
Accumulated deficit | $						$ (60,277,267)
Number Of Drug Candidates | Candidate						5

Organization, Liquidity and M29

Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies - Schedule of Computation of Basic and Diluted Net Loss per Common Share (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Numerator
Net loss attributable to common stockholders	$ (14,731,822)	$ (23,403,988)
Denominator
Weighted-average common shares outstanding	16,767,235	8,514,155
Less: Weighted-average shares subject to repurchase	(488,943)	(2,158,286)
Denominator for basic and diluted net loss per share	16,278,292	6,355,869
Basic and diluted net loss per share	$ (0.90)	$ (3.68)

Organization, Liquidity and M30

Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded in calculation of diluted net loss per share	14,458,811	1,862,509
Common stock warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded in calculation of diluted net loss per share	9,667,500	82,500
Restricted stock units [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded in calculation of diluted net loss per share	80,625	75,750
Common stock subject to repurchase [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded in calculation of diluted net loss per share	307,096	667,963
Stock options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded in calculation of diluted net loss per share	883,837	365,394
Convertible Debt Securities [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded in calculation of diluted net loss per share	3,519,753	670,902

Investments in Marketable Sec31

Investments in Marketable Securities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Available For Sale Securities [Abstract]
Proceeds from sales of available-for-sale securities	$ 0	$ 0

Investments in Marketable Sec32

Investments in Marketable Securities - Summary of Investments Classified As Available-For-Sale Securities (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		$ 13,342,869
Gross Unrealized Losses		(7,370)
Aggregate Estimated Fair Value	$ 10,075,058	13,335,499
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		5,851,343
Aggregate Estimated Fair Value		5,851,343
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,081,950	7,491,526
Gross Unrealized Losses	(6,892)	(7,370)
Aggregate Estimated Fair Value	$ 10,075,058	$ 7,484,156

Investments in Marketable Sec33

Investments in Marketable Securities - Summary of Investments Classified As Available-For-Sale Securities (Parenthetical) (Detail)	Dec. 31, 2016USD ($)Security	Dec. 31, 2015USD ($)Security
Schedule of Available-for-sale Securities [Line Items]
Number of securities in unrealized loss position | Security	25	14
Unrealized losses, aggregate		$ 7,370
Short-term investments – available for sale	$ 10,075,058	13,335,499
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, aggregate	6,892	7,370
Short-term investments – available for sale	10,075,058	7,484,156
Short-term investments classified as available-for-sale, noncurrent	0	0
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments – available for sale		5,851,343
Short-term investments classified as available-for-sale, noncurrent		0
Cash equivalents [Member] | Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments – available for sale	0	0
Cash equivalents [Member] | Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments – available for sale		0
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, individually	1,000	2,000
Unrealized losses, aggregate	$ 7,000	$ 8,000

Fair Value of Financial Instr34

Fair Value of Financial Instruments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)
Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net proceeds from initial public offering	$ 20,000,000

Fair Value of Financial Instr35

Fair Value of Financial Instruments - Summary of Fair Values of Financial Instruments (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Financial assets carried at fair value:
Short-term investments – available for sale	$ 10,075,058	$ 13,335,499
Total financial assets	12,594,380	13,884,371
Financial liabilities carried at fair value:
Debt conversion feature - long-term	731,048	2,370,903
Total financial liabilities	731,048	2,370,903
Money market funds [Member]
Financial assets carried at fair value:
Cash and cash equivalents, fair value disclosure	2,519,322	548,872
Corporate debt securities, available-for-sale [Member]
Financial assets carried at fair value:
Short-term investments – available for sale	10,075,058	7,484,156
Certificates of deposit [Member]
Financial assets carried at fair value:
Short-term investments – available for sale		5,851,343
Level 1 [Member]
Financial assets carried at fair value:
Total financial assets	2,519,322	6,400,215
Level 1 [Member] | Money market funds [Member]
Financial assets carried at fair value:
Cash and cash equivalents, fair value disclosure	2,519,322	548,872
Level 1 [Member] | Certificates of deposit [Member]
Financial assets carried at fair value:
Short-term investments – available for sale		5,851,343
Level 2 [Member]
Financial assets carried at fair value:
Total financial assets	10,075,058	7,484,156
Level 2 [Member] | Corporate debt securities, available-for-sale [Member]
Financial assets carried at fair value:
Short-term investments – available for sale	10,075,058	7,484,156
Level 3 [Member]
Financial liabilities carried at fair value:
Debt conversion feature - long-term	731,048	2,370,903
Total financial liabilities	$ 731,048	$ 2,370,903

Fair Value of Financial Instr36

Fair Value of Financial Instruments - Summary of Changes in Accrued License Fees and Debt Conversion Feature Liability Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Detail) - Debt Conversion Feature Liability [Member] - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 2,370,903	$ 1,449,211
Adjustments resulting from modification of debt	(575,685)
Adjustments resulting from changes in fair value recognized in earnings	(1,064,170)	1,043,478
Issuance of shares of common stock		(121,786)
Ending balance	$ 731,048	$ 2,370,903

Fair Value of Financial Instr37

Fair Value of Financial Instruments - Schedule of Valuation Techniques and Significant Unobservable Inputs Used to Determine Fair Value of Significant Level 3 Liabilities (Detail) - Debt Conversion Feature Liability [Member] - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Liabilities	$ 731,048	$ 2,370,903	$ 1,449,211
Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Assets	0	0
Fair Value, Liabilities	$ 731,048	$ 2,370,903
Valuation Technique(s)	Black-Scholes-Merton option valuation model	Discounted cash flow model
Level 3 [Member] | Black-Scholes-Merton Option Valuation Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Assumptions, Volatility	61.00%
Fair Value Assumptions, Risk Free Rate	0.57%
Level 3 [Member] | Discounted Cash Flow Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Timing of the events, Range		May 21, 2016
Probabilities of Occurrence Discount rate, Range		100.00%
Discount rate, Range		37.50%

Agreements with Ligand Pharma38

Agreements with Ligand Pharmaceuticals Incorporated - Additional Information (Detail) - USD ($)	Apr. 29, 2016	Apr. 13, 2016	Jan. 22, 2016	Apr. 28, 2015	Sep. 06, 2014	Apr. 30, 2016	May 31, 2014	Dec. 31, 2016
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
License agreement entered date								2014-05
Common stock issued as part of partial consideration of agreement	1,125,000	7,500,000				8,625,000
Date of registration rights agreement amendment								Jan. 22, 2016
Registration Rights Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Period to file registration statement			1 year
Ligand [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock issued as part of partial consideration of agreement		560,000
One time nonrefundable mile stone payments maximum payable amount								$ 1,540,000,000
Legal costs								$ 0
Sale and transfer of price equals to percentage of cost of goods								125.00%
Ligand [Member] | Research and development expenses [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Incremental charges incurred					$ 517,960
Ligand [Member] | Loan and Security Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Maximum aggregate loan amount					$ 2,500,000
Ligand [Member] | Management Rights Letter [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Date agreement might terminate							May 21, 2024
Ligand [Member] | Management Rights Letter [Member] | Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Voting power of the surviving or acquiring entity							50.00%
Ligand [Member] | Management Rights Letter [Member] | Minimum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of voting interest beneficiary owned							7.50%
IPO [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock issued as part of partial consideration of agreement				3,000,000
IPO [Member] | Ligand [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock issued as part of partial consideration of agreement								3,655,964
Common stock issued value as part of partial consideration of agreement								$ 29,200,000

Accrued License Fees and Lice39

Accrued License Fees and License Fees Expense - Additional Information (Detail) - USD ($)	May 04, 2015	Dec. 31, 2016	Dec. 31, 2015	May 31, 2015
Accrued License Fees And License Fees Expense [Line Items]
Common stock, shares issued	3,655,964	20,823,873	9,683,741
Estimated aggregate value of common stock		$ 208	$ 97
License fee liability	$ 29,247,711
Incremental charge	9,381,848
Additional paid-in capital	29,247,711	$ 68,326,818	$ 54,277,716
Maximum [Member]
Accrued License Fees And License Fees Expense [Line Items]
Exit scenario		50.00%
IPO [Member]
Accrued License Fees And License Fees Expense [Line Items]
Estimated aggregate value of common stock		$ 29,200,000
License fee liability	$ 27,422,872			$ 24,826,374
Ligand [Member] | IPO [Member]
Accrued License Fees And License Fees Expense [Line Items]
Common stock, shares issued		3,655,964

Convertible Notes Payable - Sch

Convertible Notes Payable - Schedule of Convertible Notes Payable (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Conversion payoff value	$ 1,990,032
Discount on notes payable, current	(675,589)	$ 0
Convertible notes payable, current portion (net of discount)	3,269,582
Discount on notes payable, long-term	0	(348,460)
Convertible notes payable, long-term (net of discount)		2,151,540
Ligand Note [Member] | Short Term Debt [Member]
Debt Instrument [Line Items]
Convertible note payable issued during 2014 to Ligand pursuant to the Master License Agreement with a 5% annual interest rate, due during 2016 (amended in January 2016 to a 2.5% annual interest rate with maturity extended to 2017)	$ 1,955,139
Ligand Note [Member] | Long Term Debt [Member]
Debt Instrument [Line Items]
Convertible note payable issued during 2014 to Ligand pursuant to the Master License Agreement with a 5% annual interest rate, due during 2016 (amended in January 2016 to a 2.5% annual interest rate with maturity extended to 2017)		$ 2,500,000

Convertible Notes Payable - S41

Convertible Notes Payable - Schedule of Convertible Notes Payable (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Interest rate for current maturities	2.50%	5.00%
Due date for current maturities	2,017	2,016
Interest rate of Long-term maturities	2.50%	5.00%
Due date for Long-term maturities	2,017	2,016

Convertible Notes Payable - Add

Convertible Notes Payable - Additional Information (Detail) - USD ($)	Apr. 29, 2016	Apr. 13, 2016	Jan. 22, 2016	Apr. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Jan. 21, 2016	Dec. 31, 2014
Debt Instrument [Line Items]
Date of registration rights agreement amendment					Jan. 22, 2016
Proceeds from issuances of common stock, net of underwriting discounts and commissions	$ 1,283,400	$ 7,754,286		$ 9,037,686	$ 11,548,518	$ 25,392,500
Underwriting discounts, commissions and other offering expenses	$ 111,600	$ 1,631,964		$ 1,743,564
Repayments of notes payable in stock					$ 1,200,000
Common stock sold	1,125,000	7,500,000		8,625,000
Warrants sold		7,500,000		8,625,000
Exercise price per share of common stock		$ 1.50		$ 1.50	$ 10
Warrants expiry date				Apr. 13, 2021	Apr. 13, 2021
Amortization of debt discount					$ 1,788,088	893,502
(Expense) income related to debt conversion feature liability					1,064,170	(1,043,478)
Ligand [Member]
Debt Instrument [Line Items]
Common stock sold		560,000
Warrants sold		560,000
Ligand Note [Member]
Debt Instrument [Line Items]
Note obligation					1,500,000
Next financing payment to be paid in cash					300,000
Repayments of notes payable in stock					1,200,000
Interest expense					105,551	125,000
Amortization of debt discount					1,788,088	887,426
(Expense) income related to debt conversion feature liability					$ 1,064,170
Other expenses related to debt conversion feature						$ 980,434
Loan and Security Agreement [Member]
Debt Instrument [Line Items]
Aggregate net proceeds from issue of equity securities			$ 2,000,000
Shares issued price per share			$ 8
Debt Instrument repayment, description					Each $1.00 of the $1,500,000 payment reduced the amount of accrued and unpaid interest and then unpaid principal amount of the loans under the Ligand Note by $0.50.
Additional repayment notice period within closing of the next financing					180 days
Additional repayment notice period after the closing of the next financing					180 days
Weighted average closing price of common stock period					30 days
Securities dispose date					Jan. 23, 2017
Loan and Security Agreement [Member] | Ligand [Member]
Debt Instrument [Line Items]
Repayments of notes payable in stock		$ 1,200,000
Common stock sold		960,000
Warrants sold		960,000
Exercise price per share of common stock		$ 1.50
Warrants expiry date					Apr. 13, 2021
Loan and Security Agreement [Member] | Ligand Note [Member]
Debt Instrument [Line Items]
Note obligation			$ 1,500,000
Loan and Security Agreement [Member] | Ligand Note [Member] | Minimum [Member]
Debt Instrument [Line Items]
Next financing payment to be paid in cash			$ 300,000
Debt Conversion Feature Liability [Member]
Debt Instrument [Line Items]
Adjustments resulting from modification of debt					$ 575,685
Debt Conversion Feature Liability [Member] | Ligand Note [Member]
Debt Instrument [Line Items]
Adjustments resulting from modification of debt					$ 575,685
Ligand Debt
Debt Instrument [Line Items]
Loan and security agreement								$ 2,500,000
Fixed accrued interest rate			2.50%				5.00%
Fixed accrued interest rate of default loan					8.00%
Loan and security agreement, maturity date					May 21, 2017
Note conversion, principal amount of loan plus all accrued and previously unpaid interest					200.00%

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) - Additional Information (Detail)	Aug. 24, 2016USD ($)$ / sharesshares	Jun. 20, 2016shares	Apr. 29, 2016USD ($)shares	Apr. 27, 2016$ / sharesshares	Apr. 13, 2016USD ($)$ / sharesshares	May 28, 2015USD ($)shares	May 26, 2015$ / sharesshares	May 04, 2015USD ($)$ / sharesshares	Apr. 28, 2015$ / sharesshares	Apr. 30, 2016USD ($)$ / sharesshares	May 31, 2015USD ($)$ / sharesshares	Feb. 28, 2014Tranche$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Jan. 22, 2016	Feb. 20, 2014USD ($)
Equity [Line Items]
Preferred stock, shares authorized													10,000,000	10,000,000	10,000,000
Preferred stock, par value | $ / shares													$ 0.00001	$ 0.00001	$ 0.00001
Preferred stock, shares outstanding													0	0	0
Common stock, shares authorized													300,000,000	300,000,000	300,000,000
Common stock, par value | $ / shares													$ 0.00001	$ 0.00001	$ 0.00001
Number of common stock for issuance in exchange for future services from founders												1,000,000
Common stock price per share | $ / shares												$ 0.01
Number of tranches | Tranche												2
Unrecognized compensation expense | $											$ 61,556						$ 168,000
Common stock shares repurchased											633,810
Repurchase of common stock from stockholders, per share | $ / shares											$ 0.00001
Remaining number of repurchased shares											366,190
Common stock sold			1,125,000		7,500,000					8,625,000
Common stock, price per share | $ / shares					$ 1.25					$ 1.25
Number of additional common shares pursuant to over-allotment option granted to the underwriters					1,125,000
Cash proceeds from common stock issuance | $			$ 1,283,400		$ 7,754,286					$ 9,037,686			$ 11,548,518	$ 25,392,500
Underwriting discounts, commissions and other offering expenses | $			$ 111,600		$ 1,631,964					$ 1,743,564
Repurchase of common stock from stockholders, value | $														$ 38
Granted, Shares													620,818
Accrued license fees | $								$ 29,247,711
Convertible notes payable, current | $													$ 3,269,582		$ 3,269,582
Convertible notes payable, interest | $													$ 34,894		$ 34,894
Warrants sold					7,500,000					8,625,000
Exercise price per share of common stock | $ / shares					$ 1.50					$ 1.50			$ 10		$ 10
Underwriters grant period option					45 days
Additional warrants granted to underwriters					1,125,000
Additional warrants sold as a result of over allotment exercise					1,125,000
Public offering price per warrant | $ / shares					$ 0.01
Warrants expiry date										Apr. 13, 2021			Apr. 13, 2021
Repayments of notes payable in stock | $													$ 1,200,000
Over-allotment option exercised				1,125,000
Shares issued as commitment fee in connection with Aspire agreement | $													$ 440,278
Shares issued under ESPP													21,616	5,711
Common Stock [Member]
Equity [Line Items]
Common stock sold														3,655,964
Repurchase of common stock														3,802,859
Repurchase of common stock from stockholders, value | $														$ 38
Common stock, shares issued for services														4,882
Minimum [Member] | Loan and Security Agreement [Member]
Equity [Line Items]
Beneficial ownership of company's common stock					49.90%											49.90%
Non-employee Directors [Member]
Equity [Line Items]
Granted, Shares									83,144
Ligand [Member]
Equity [Line Items]
Common stock sold					560,000
Warrants sold					560,000
Ligand [Member] | Loan and Security Agreement [Member]
Equity [Line Items]
Common stock sold					960,000
Warrants sold					960,000
Exercise price per share of common stock | $ / shares					$ 1.50
Warrants expiry date													Apr. 13, 2021
Repayments of notes payable in stock | $					$ 1,200,000
Maxim [Member]
Equity [Line Items]
Cash proceeds from common stock issuance | $													$ 956,518
Maxim [Member] | Common Stock [Member]
Equity [Line Items]
Common stock sold													778,849
Maxim [Member] | Maximum [Member] | Common Stock [Member]
Equity [Line Items]
Sale of common stock, shares		3,748,726
Aspire Capital [Member] | Common Stock [Member] | Stock Purchase Agreement [Member]
Equity [Line Items]
Common stock sold	333,333												150,000
Common stock, price per share | $ / shares	$ 1.50
Cash proceeds from common stock issuance | $													$ 173,250
Common stock sold aggregate purchase price | $	$ 500,000
Common stock purchase agreement term	30 months
Minimum closing sale price per share to execute transactions under agreement | $ / shares	$ 0.40
Common stock issued as consideration for commitment fee	336,116
Shares issued as commitment fee in connection with Aspire agreement | $													$ 440,278
Aspire Capital [Member] | Maximum [Member] | Common Stock [Member] | Stock Purchase Agreement [Member]
Equity [Line Items]
Common stock sold aggregate purchase price | $	$ 12,500,000
IPO [Member]
Equity [Line Items]
Repurchase of common stock from stockholders, per share | $ / shares								$ 0.00001
Anniversary date of closing													May 4, 2015
Common stock sold									3,000,000
Common stock, price per share | $ / shares							$ 8		$ 8
Underwriters option exercise period													30 days
Number of additional common shares pursuant to over-allotment option granted to the underwriters						450,000			450,000
Cash proceeds from common stock issuance | $						$ 3,225,866		$ 19,100,500
Underwriting discounts, commissions and other offering expenses | $						$ 374,134		$ 4,899,500
Repurchase of common stock								3,802,859
Repurchase of common stock from stockholders, value | $								$ 38
Accrued license fees | $								27,422,872			$ 24,826,374
Non-cash interest charge | $								4,421,338
Convertible notes payable, current | $								310,350
Convertible notes payable, interest | $								$ 24,276
Convertible notes payable and interest conversion, shares issued								57,046
Beneficial conversion charge | $													$ 121,786
Additional shares purchase under underwriting agreement							450,000
IPO [Member] | Accrued License Fees [Member]
Equity [Line Items]
Common stock, shares issued for services								3,427,859
IPO [Member] | Employees, Directors and Consultants [Member]
Equity [Line Items]
Common stock sold													422,879
Granted, Shares													206,000
IPO [Member] | Ligand And Metabasis Therapeutics Inc [Member]
Equity [Line Items]
Common stock sold						228,105
Common stock, shares issued for services								3,427,859
IPO [Member] | Ligand [Member]
Equity [Line Items]
Common stock sold													3,655,964
Common stock sold aggregate purchase price | $													$ 29,200,000
Over-Allotment Option [Member]
Equity [Line Items]
Common stock, price per share | $ / shares				$ 1.24
Warrants sold					1,125,000
Tranche One [Member]
Equity [Line Items]
Number of common stock for issuance in exchange for future services from founders												500,000
Remaining number of repurchased shares											183,095
Stock compensation expense | $													$ 12,371	$ 18,407	$ 30,778
Tranche Two [Member]
Equity [Line Items]
Number of common stock for issuance in exchange for future services from founders												500,000
Remaining number of repurchased shares											183,095

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)Period$ / sharesshares	Jan. 01, 2016shares	Dec. 31, 2015shares	Apr. 28, 2015shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance	15,310,692		2,420,795
Weighted average fair value of stock options granted to employees | $ / shares	$ 1.40
Options outstanding, Aggregate Intrinsic Value | $	$ 0
Options exercisable, Aggregate Intrinsic Value | $	0
Excess tax benefit from stock-based awards | $	$ 0
2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance				1,527,770
Additional number of shares of common stock reserved for issuance		338,930
Common stock reserved for issuance, description	Initially, a total of 1,527,770 shares of the Company’s common stock were reserved for issuance pursuant to the 2014 Plan, which number is also the limit on shares of common stock available for awards of incentive stock options. The number of shares available for issuance under the 2014 Plan will, unless otherwise determined by the Company’s Board of Directors or the Compensation Committee, be automatically increased on January 1st of each year commencing on January 1, 2016 and ending on (and including) January 1, 2024, in an amount equal to 3.5% of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year.
Percentage of common stock outstanding to increase shares reserved for issuance	3.50%
2014 ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance				458,331
Additional number of shares of common stock reserved for issuance		96,837
Common stock reserved for issuance, description	The number of shares available for issuance under the ESPP will, unless otherwise determined by the Company’s Board of Directors or the Compensation Committee, be automatically increased on January 1st of each year commencing on January 1, 2016 and ending on (and including) January 1, 2024, in an amount equal to 1% of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year.
Percentage of common stock outstanding to increase shares reserved for issuance	1.00%
Duration of employee stock purchase plan as determined by the compensation committee	24 months
Duration for offering period, employee stock purchase plan	6 months
Employee stock purchase plan, number of purchase periods | Period	4
Maximum duration for purchase under employee stock purchase plan	1 year
Maximum duration of employee stock purchase plan	27 months
Percentage of purchase of common stock	85.00%
Percentage of common stock on the date of purchase	85.00%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-based Compensation Expense Recognized (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	$ 1,794,327	$ 2,601,448
Research and development expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	537,008	852,200
General and administrative expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	1,257,319	1,749,248
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	921,556	949,955
Restricted stock and restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	836,964	1,608,049
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	$ 35,807	$ 43,444

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Unrecognized Stock-based Compensation Expense, Net of Estimated Forfeitures, by Type of Award and Weighted-average Recognition Period (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	May 31, 2015	Feb. 20, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense, Net of Estimated Forfeitures		$ 61,556	$ 168,000
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense, Net of Estimated Forfeitures	$ 1,042,226
Weighted-average Recognition Period	2 years 5 months 1 day
Restricted stock and restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense, Net of Estimated Forfeitures	$ 1,165,141
Weighted-average Recognition Period	1 year 8 months 16 days

Stock-Based Compensation - Su47

Stock-Based Compensation - Summary of Restricted Shares Granted (Detail) - Restricted shares [Member]	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Unvested, Beginning balance | shares	667,963
Shares, Vested | shares	(291,313)
Shares, Forfeited | shares	(69,554)
Shares, Unvested, Ending balance | shares	307,096
Weighted-Average Grant Date Fair Value, Unvested, Beginning balance | $ / shares	$ 3.73
Weighted-Average Grant Date Fair Value, Vested | $ / shares	2.89
Weighted-Average Grant Date Fair Value, Forfeited | $ / shares	6.37
Weighted-Average Grant Date Fair Value, Unvested, Ending balance | $ / shares	$ 3.93

Stock-Based Compensation - Su48

Stock-Based Compensation - Summary of Restricted Stock Units Activity (Detail) - Restricted stock units [Member]	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Unvested, Beginning balance | shares	75,750
Shares, Granted | shares	40,000
Shares, Vested | shares	(28,937)
Shares, Forfeited | shares	(6,188)
Shares, Unvested, Ending balance | shares	80,625
Weighted-Average Grant Date Fair Value, Unvested, Beginning balance | $ / shares	$ 8.27
Weighted-Average Grant Date Fair Value, Granted | $ / shares	1.19
Weighted-Average Grant Date Fair Value, Vested | $ / shares	5.83
Weighted-Average Grant Date Fair Value, Forfeited | $ / shares	7.25
Weighted-Average Grant Date Fair Value, Unvested, Ending balance | $ / shares	$ 5.72

Stock-Based Compensation - Su49

Stock-Based Compensation - Summary of Stock Option Activity (Detail)	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding beginning balance, Shares | shares	365,394
Granted, Shares | shares	620,818
Cancelled, Shares | shares	(102,375)
Options outstanding ending balance, Shares | shares	883,837
Options exercisable, Shares | shares	301,824
Options outstanding beginning balance, Weighted-Average Exercise Price | $ / shares	$ 8.48
Granted, Weighted-Average Exercise Price | $ / shares	2.01
Cancelled, Weighted-Average Exercise Price | $ / shares	5.55
Options outstanding ending balance, Weighted-Average Exercise Price | $ / shares	4.28
Options exercisable, Weighted-Average Exercise Price | $ / shares	$ 5.72
Options outstanding, Weighted-Average Remaining Contractual Term	8 years 10 months 13 days
Options exercisable, Weighted-Average Remaining Contractual Term	8 years 4 months 24 days

Stock-Based Compensation - Sc50

Stock-Based Compensation - Schedule of Weighted Average Assumptions using Black-Scholes Option Pricing Model (Detail)	12 Months Ended
	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]
Expected volatility	82.60%
Expected term (in years)	5 years 10 months 24 days
Risk-free interest rate	1.59%
Expected dividend yield	0.00%

Stock-Based Compensation - Comm

Stock-Based Compensation - Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	15,310,692	2,420,795
Common stock warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	9,667,500	82,500
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	80,625	75,750
Common stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	883,837	365,394
Available for grant under the 2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	631,136	773,629
Available for issuance under Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	527,841	452,620
Shares issuable upon conversion of Ligand debt [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	3,519,753	670,902

Warrants - Additional Informati

Warrants - Additional Information (Detail) - USD ($)	Feb. 14, 2017	Apr. 29, 2016	Apr. 13, 2016	May 04, 2015	Apr. 30, 2016	Dec. 31, 2016	Apr. 27, 2016	Jan. 22, 2016
Class of Warrant or Right [Line Items]
Issuance of shares of common stock		1,125,000	7,500,000		8,625,000
Exercise price of warrant			$ 1.50		$ 1.50	$ 10
Warrant description						The warrant is exercisable for cash or on a cashless basis at a per share exercise price equal to $10.00 commencing on April 28, 2016, one year following the date of the prospectus filed with the SEC relating to the IPO, and expiring on April 28, 2020. In addition, the warrant provides for registration rights upon request, under certain circumstances. The piggyback registration right provided in connection with the warrant will terminate on April 28, 2022.
Warrant termination date						Apr. 28, 2022
Initial public offering, expiration date						Apr. 28, 2020
Warrants sold			7,500,000		8,625,000
Common stock, price per share			$ 1.25		$ 1.25
Warrants expiry date					Apr. 13, 2021	Apr. 13, 2021
Public offering price per warrant			$ 0.01
Repayments of notes payable in stock						$ 1,200,000
Loan and Security Agreement [Member] | Minimum [Member]
Class of Warrant or Right [Line Items]
Beneficial ownership of company's common stock			49.90%					49.90%
Ligand [Member]
Class of Warrant or Right [Line Items]
Issuance of shares of common stock			560,000
Warrants sold			560,000
Ligand [Member] | Loan and Security Agreement [Member]
Class of Warrant or Right [Line Items]
Issuance of shares of common stock			960,000
Exercise price of warrant			$ 1.50
Warrants sold			960,000
Warrants expiry date						Apr. 13, 2021
Repayments of notes payable in stock			$ 1,200,000
Over-Allotment Option [Member]
Class of Warrant or Right [Line Items]
Warrants sold			1,125,000
Common stock, price per share							$ 1.24
Subsequent Event [Member]
Class of Warrant or Right [Line Items]
Resale of common stock issuable upon exercise of warrant	82,500
Common stock warrants [Member]
Class of Warrant or Right [Line Items]
Issuance of shares of common stock				82,500

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliations of the U.S. Federal Statutory Tax Rate to the Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax provision at U.S. Federal statutory rates	34.00%	34.00%
State income taxes net of federal benefit	3.00%	8.00%
Non-deductible permanent items	(7.00%)	(2.00%)
Stock options	0.00%	0.00%
Other	0.00%	0.00%
Change in valuation allowance	(30.00%)	(40.00%)
Effective income tax rate	0.00%	0.00%

Income Taxes - Schedule of Sign

Income Taxes - Schedule of Significant Components of Company's Deferred Taxes (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Accrued liabilities	$ 59,333	$ 48,982
Intangible assets	16,388,591	14,009,497
Net operating loss carryforwards	4,558,964	2,430,249
Share-based compensation	1,289,957	986,534
Share conversion feature		243,759
Other	3,017	3,510
Total deferred tax assets	22,299,862	17,722,531
Valuation Allowance	(22,115,992)	(17,722,531)
Total deferred tax assets, net of allowance	183,870
Deferred tax liabilities:
Debt conversion feature	(183,870)
Total deferred tax liabilities:	(183,870)
Net deferred tax assets (liabilities):	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Valuation Allowance	$ 22,115,992	$ 17,722,531
Federal net operating loss carryforwards	11,468,000
State net operating loss carryforwards	$ 11,307,000
Federal and state net operating loss carryforwards, begin to expiration year.	2,032
Description of the limitations on the use of all operating loss carryforwards	Specifically, this limitation may arise in the event of an “ownership change,” which is defined by Section 382 of the Code as a cumulative change in ownership of the Company of more than 50% within a three-year period. If the Company undergoes one or more ownership changes in connection with any future transactions in its stock, the Company’s ability to utilize net operating loss carryforwards to offset federal taxable income, if any, could potentially result in increased future tax liability to the Company. An ownership change under Section 382 of the Code occurred during the year ended December 31, 2015 in connection with the Company’s initial public offering. A portion of the net operating loss carryforwards are subject to an annual limitation.
Percentage of cumulative change in stock ownership.	50.00%
Tax benefit not recognized	$ 0	0
Liability for uncertain tax positions	$ 0	$ 0

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail)	Dec. 31, 2016
Ligand [Member]
Related Party Transaction [Line Items]
Equity method investment, ownership percentage	35.00%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Jul. 07, 2015USD ($)ft²	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Commitments And Contingencies [Line Items]
Rent expense		$ 253,316	$ 142,288
California [Member] | Sublease [Member]
Commitments And Contingencies [Line Items]
Area of subleased premises | ft²	7,049
Monthly base rent payments	$ 19,737
Percentage of rent increase under sublease	3.00%

Commitments and Contingencies58

Commitments and Contingencies - Summary of Future Minimum Payments for Sublease (Detail)	Dec. 31, 2016USD ($)
Operating Leases, Future Minimum Payments [Abstract]
2,017	$ 227,282
2,018	190,337
Total minimum lease payments	$ 417,619

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($)	Mar. 21, 2017	Feb. 08, 2017	Apr. 29, 2016	Apr. 13, 2016	Apr. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Common stock sold			1,125,000	7,500,000	8,625,000
Cash proceeds from common stock issuance			$ 1,283,400	$ 7,754,286	$ 9,037,686	$ 11,548,518	$ 25,392,500
Maxim and Aspire Capital [Member] | Distribution and Purchase Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Cash proceeds from common stock issuance	$ 2,539,543
Common Stock [Member]
Subsequent Event [Line Items]
Common stock sold							3,655,964
Common Stock [Member] | Maxim and Aspire Capital [Member] | Distribution and Purchase Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Common stock sold	1,815,379
Common Stock [Member] | PoC Capital, LLC [Member] | Stock Purchase Agreement [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Common stock sold		1,286,173
Common stock sold aggregate purchase price		$ 1,800,000