Viking Therapeutics (VKTX) 10-Q 5 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Nov. 02, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Trading Symbol	VKTX
Entity Registrant Name	Viking Therapeutics, Inc.
Entity Central Index Key	1,607,678
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		9,678,312

Balance Sheets

Balance Sheets - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 2,140,115	$ 755,857
Short-term investments – available for sale	15,349,507
Prepaid expenses and other current assets	1,442,629	17,827
Total current assets	18,932,251	773,684
Deferred IPO financing costs		2,268,675
Other assets	80,000	775
Total assets	19,012,251	3,043,134
Current liabilities:
Accounts payable	401,672	1,830,724
Accrued license fees		19,865,863
Other accrued liabilities	1,103,432	380,257
Accrued interest	152,361	77,222
Convertible notes payable, current portion (net of discount of $588,976 and $6,076 at September 30, 2015 and December 31, 2014, respectively)	1,911,024	304,274
Debt conversion feature liability	2,154,062	58,742
Total current liabilities	5,722,551	22,517,082
Convertible notes payable (net of discount of $0 and $1,235,886 at September 30, 2015 and December 31, 2014, respectively)		1,264,114
Debt conversion feature liability		1,390,469
Deferred rent	19,149
Total long-term liabilities	19,149	2,654,583
Total liabilities	$ 5,741,700	$ 25,171,665
Commitments and contingencies (Note 7)
Stockholders’ equity (deficit):
Common stock, $0.00001 par value: 300,000,000 shares authorized at September 30, 2015 and 25,000,000 shares authorized at December 31, 2014; 9,783,312 shares issued and outstanding at September 30, 2015 and 6,000,000 shares issued and outstanding at December 31, 2014	$ 98	$ 60
Additional paid-in capital	53,729,783	12,866
Accumulated deficit	(40,454,482)	(22,141,457)
Accumulated other comprehensive loss	(4,848)
Total stockholders’ equity (deficit)	13,270,551	(22,128,531)
Total liabilities and stockholders’ equity (deficit)	$ 19,012,251	$ 3,043,134

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Convertible notes payable, discount, current portion	$ 588,976	$ 6,076
Convertible notes payable, discount, noncurrent portion	$ 0	$ 1,235,886
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	300,000,000	25,000,000
Common stock, shares issued	9,783,312	6,000,000
Common stock, shares outstanding	9,783,312	6,000,000

Statements of Operations and Co

Statements of Operations and Comprehensive Loss (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Revenues	$ 0	$ 0	$ 0	$ 0
Operating expenses:
Research and development	2,507,553	788,646	3,747,428	22,080,286
General and administrative	1,780,668	360,403	3,628,747	1,034,132
Total operating expenses	4,288,221	1,149,049	7,376,175	23,114,418
Loss from operations	(4,288,221)	(1,149,049)	(7,376,175)	(23,114,418)
Other income (expense):
Change in fair value of accrued license fees		695,251	(9,381,848)	(264,112)
Change in fair value of debt conversion feature liability	(197,496)	413,703	(826,637)	405,782
Amortization of debt discount	(240,515)	(196,669)	(652,986)	(263,651)
Interest expense, net	(10,312)	(25,037)	(75,379)	(37,131)
Total other income (expense)	(448,323)	887,248	(10,936,850)	(159,112)
Net loss	(4,736,544)	(261,801)	(18,313,025)	(23,273,530)
Other comprehensive loss, net of tax:
Unrealized gain (loss) on securities	7,613		(4,848)
Comprehensive loss	$ (4,728,931)	$ (261,801)	$ (18,317,873)	$ (23,273,530)
Basic and diluted net loss per share	$ (0.53)	$ (0.06)	$ (2.69)	$ (5.84)
Weighted-average shares used to compute basic and diluted net loss per share	8,947,480	4,518,439	6,802,169	3,982,147

Statements of Cash Flows (Unaud

Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities
Net loss	$ (261,801)	$ (18,313,025)	$ (23,273,530)
Adjustments to reconcile net loss to net cash used in operating activities
Amortization of debt discount on notes payable	196,669	652,986	263,651
Amortization of investment premiums		67,692
Change in fair value of accrued license fees	(695,251)	9,381,848	264,112
Change in fair value of debt conversion feature liability	(413,703)	826,637	(405,782)
Stock-based compensation		2,074,004	5,355
Changes in operating assets and liabilities:
Prepaid expenses and other current assets		(1,504,027)	(16,781)
Accounts payable		137,286	84,727
Accrued license fees			21,687,576
Accrued expenses		1,244,495	240,215
Net cash used in operating activities		(5,432,104)	(1,150,457)
Cash flows from investing activities
Purchases of investments		(16,033,042)
Proceeds from sales and maturities of investments		607,000
Net cash used in investing activities		(15,426,042)
Cash flows from financing activities
Net proceeds from issuances of common stock		25,392,500
Public offering costs		(2,733,798)	(234,745)
Value of shares withheld related to employee tax withholding		(418,412)
Repurchases of common stock		(38)	(2)
Proceeds from convertible notes payable			2,000,000
Proceeds from stock issuance under employee stock purchase plan		2,152
Net cash provided by financing activities		22,242,404	1,765,253
Net increase in cash and cash equivalents		1,384,258	614,796
Cash and cash equivalents beginning of period		755,857	179,619
Cash and cash equivalents end of period	794,415	2,140,115	794,415
Supplemental disclosure of non-cash investing and financing transactions
Shares issued in lieu of license fee		29,247,711
Unpaid deferred IPO costs	$ 1,895,950		$ 1,895,950
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	9 Months Ended
	Sep. 30, 2015
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, first-in-class or best-in-class 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, California. Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The accompanying balance sheet as of September 30, 2015, statements of operations for the three and nine months ended September 30, 2015 and 2014 and statements of cash flows for the nine months ended September 30, 2015 and 2014 are unaudited. These unaudited financial statements have been prepared in accordance with the rules and regulations of the United States Securities and Exchange Commission (“SEC”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. These financial statements should be read in conjunction with the audited financial statements and the accompanying notes for the year ended December 31, 2014 contained in the final prospectus filed by the Company with the SEC on April 29, 2015 relating to the Company’s initial public offering (the “IPO”). The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments (consisting of normal recurring adjustments) necessary to state fairly the Company’s financial position as of September 30, 2015 and the results of operations for the three and nine months ended September 30, 2015 and 2014 and cash flows for the nine months ended September 30, 2015 and 2014. The December 31, 2014 balance sheet included herein was derived from the audited financial statements, but does not include all disclosures or notes required by GAAP for complete financial statements. The financial data and other information disclosed in these notes to the financial statements related to the three and nine months ended September 30, 2015 and 2014 are unaudited. Interim results are not necessarily indicative of results for an entire year. 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. Recent Accounting Pronouncements For a discussion of recent accounting pronouncements, please refer to Note 1, “Organization, Liquidity and Management’s Plan, and Summary of Significant Accounting Policies” of the financial statements in the final prospectus filed by the Company with the SEC on April 29, 2015 relating to the IPO. The Company did not adopt any new accounting pronouncements during the nine months ended September 30, 2015 that had a material effect on its condensed financial statements. 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 May 2015, the Company completed the IPO, issuing 3,450,000 shares of its common stock and raising $25,392,500 in net proceeds, including the full exercise of the over-allotment option, and after deducting underwriting discounts, commissions and a non-accountable expense in an aggregate amount of $2,207,500, but before deducting other offering costs and expenses. These additional funds raised in May 2015 alleviate any doubt in regards to the Company’s ability to continue as a going concern over the next 12 months. (See Note 4 regarding proceeds from the IPO received in May 2015.) Deferred IPO Financing Costs Deferred IPO financing costs represent legal, accounting and other direct costs related to the Company’s efforts to raise capital through a public sale of the Company’s common stock. Costs related to the IPO were deferred until the completion of the IPO, at which time they were reclassified to additional paid-in capital as a reduction of the IPO proceeds. Through September 30, 2015, $3,066,136 of offering costs were recorded as a reduction of the proceeds received. 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 to be recognized over the period that any related services are to be provided by the Company. Amounts received for research funding are to be 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 to be recorded as revenue for the gross amount of the reimbursement, and the costs associated with these reimbursements are to be reflected as a component of research and development expense in the statements of operations. Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 605-28, Revenue Recognition – Milestone Method 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 clinical 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. The Company’s historical research and development expenses primarily related to obtaining the option to license compounds and related intellectual property rights from Ligand Pharmaceuticals Incorporated (“Ligand”). In May 2014, the Company entered into a master license agreement with Ligand, as amended (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. Prior to 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 are deemed probable of being met, then the Company will then begin 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 are 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. Income tax positions must meet a more-likely-than-not recognition threshold to be recognized. Income tax positions that previously failed to meet the more-likely-than-not threshold are recognized in the first subsequent financial reporting period in which that threshold is met. Previously recognized tax positions that no longer meet the more-likely-than-not threshold are derecognized in the first subsequent financial reporting period in which that threshold is no longer met. 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: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Historical net loss per share Numerator Net loss attributable to common stockholders $ (4,736,544 ) $ (261,801 ) $ (18,313,025 ) $ (23,273,530 ) Denominator Weighted-average common shares outstanding 9,783,312 6,000,000 8,120,639 5,813,187 Less: Weighted-average shares subject to repurchase (835,832 ) (1,481,561 ) (1,318,470 ) (1,831,040 ) Denominator for basic and diluted net loss per share 8,947,480 4,518,439 6,802,169 3,982,147 Basic and diluted net loss per share $ (0.53 ) $ (0.06 ) $ (2.69 ) $ (5.84 ) 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): Three and Nine Months Ended September 30, 2015 2014 Common stock warrants 82,500 — Restricted stock units 84,000 — Common stock subject to repurchase 772,963 2,295,833 Common stock options 410,144 — Shares issued upon conversion of debt 663,090 — 2,012,697 2,295,833 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.

Investments in Marketable Secur

Investments in Marketable Securities	9 Months Ended
	Sep. 30, 2015
Investments Debt And Equity Securities [Abstract]
Investments in Marketable Securities	2. Investments in Marketable Securities The Company did not have any investments classified as available-for-sale as of December 31, 2014. Investments classified as available-for-sale at September 30, 2015 consisted of the following: Amortized Cost Gross Unrealized Gains (1) Gross Unrealized Losses (1) Aggregate Estimated Fair Value Money market funds (2) 1,269,047 — — 1,269,047 Certificates of deposit (3) 7,089,727 — — 7,089,727 Corporate debt securities (4) 8,264,628 975 (5,823 ) 8,259,780 $ 16,623,402 $ 975 $ (5,823 ) $ 16,618,554 (1) Unrealized gains and losses on available-for-sale securities are included as a component of comprehensive loss. At September 30, 2015, there were 12 securities in an unrealized loss position. These unrealized losses were less than $2,000 individually and $6,000 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) All money market funds are classified as cash equivalents. (3) At September 30, 2015, none of these securities were classified as cash and cash equivalents on the Company’s balance sheet and $249,348 of these securities were scheduled to mature outside of one year. (4) At September 30, 2015, none of these securities were classified as cash and cash equivalents on the Company’s balance sheet and $0 of these securities were scheduled to mature outside of one year. There were no sales of available-for-sale securities during either the three or nine months ended September 30, 2015.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2015
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. 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 September 30, 2015, the Company’s investments were in money market funds, certificates of deposit and corporate debt securities. As of September 30, 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 liabilities that were subject to fair value measurements consist 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 liability at December 31, 2014 required management to make assumptions about the probability of the occurrence of a capital stock issuance by the Company resulting in net proceeds of at least $5,000,000 and the related convertible notes being converted based on the applicable conversion terms. The fair value of the debt conversion feature – current liability as of September 30, 2015 required management to make a fair value estimate 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 liabilities: Fair Value Measurements at September 30, 2015 Total Level 1 Level 2 Level 3 Financial assets carried at fair value: Cash equivalents: Money market funds $ 1,269,047 $ 1,269,047 $ — $ — Short-term investments Certificates of deposit 7,089,727 7,089,727 — — Corporate debt securities, available-for-sale 8,259,780 — 8,259,780 — Total financial assets $ 16,618,554 $ 8,358,773 $ 8,259,780 $ — Financial liabilities carried at fair value: Debt conversion feature - current $ 2,154,062 $ — $ — $ 2,154,062 Total financial liabilities $ 2,154,062 $ — $ — $ 2,154,062 Fair Value Measurements at December 31, 2014 Total Level 1 Level 2 Level 3 Financial liabilities carried at fair value: Accrued license fees $ 19,865,863 $ — $ — $ 19,865,863 Debt conversion feature – current 58,742 — — 58,742 Debt conversion feature – long-term 1,390,469 — — 1,390,469 Total financial liabilities $ 21,315,074 $ — $ — $ 21,315,074 The table below presents a summary of changes in the Company’s accrued license fee and debt conversion feature liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three and nine months ended September 30, 2015 and 2014: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Accrued license fees: Beginning balance $ — $ 22,128,979 $ 19,865,863 $ — Additions — 517,960 — 21,687,576 Adjustments resulting from changes in fair value recognized in earnings — (695,251 ) 9,381,848 264,112 Issuance of shares of common stock — — (29,247,711 ) — Ending balance $ — $ 21,951,688 $ — $ 21,951,688 Debt conversion feature: Beginning balance $ 1,956,566 $ 1,063,543 $ 1,449,211 $ 71,655 Additions — 508,105 — 1,492,072 Adjustments resulting from changes in fair value recognized in earnings 197,496 (413,703 ) 826,637 (405,782 ) Issuance of shares of common stock — — (121,786 ) — Ending balance $ 2,154,062 $ 1,157,945 $ 2,154,062 $ 1,157,945 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 Unobservable Input Range Assets Liabilities Valuation Technique(s) Accrued license fees: December 31, 2014 $ — $ 19,865,863 Probability weighted expected return model Probability weightings assigned to each scenario 30% to 40% Time assumptions to liquidation events 4/30/2015- 3/31/2017 Discount rates 12% to 60% Debt conversion feature liability September 30, 2015 $ — $ 2,154,062 Discounted cash flow model Timing of the events 5/21/2016 Probabilities of Occurrence 100% Discount rate 37.5% December 31, 2014 $ — $ 1,449,211 Discounted cash flow model Timing of the events 3/31/2015 to 6/30/2015 Probabilities of Occurrence 30% to 40% Discount rate 37.5% Level 3 Fair Value Sensitivity Accrued License Fees For accrued license fees, generally increases (decreases) in the probability weightings assigned to each scenario would result in increases (decreases) to the fair value. In general, an increase (decrease) in discount rate tends to result in (decreases) increases to fair value. Debt Conversion Feature Liability 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.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Stockholders' Equity (Deficit)	4. Stockholders’ Equity (Deficit) 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. To appropriately account for this stock purchase, the Company determined the fair value of the common stock on the date of purchase as well as the likelihood of achievement of each of the performance conditions included in the agreement. The valuation methodology utilized in determining fair value relied on the PWERM, which incorporates relevant events and expected future exit scenarios for the Company. The exit scenarios included merger and acquisition and initial public offering scenarios. The enterprise value under each scenario was based primarily on the market approach and probability-weighted expected exit values for the Company under each scenario. Similar merger and acquisition transactions and publicly traded companies were utilized within the market approach and appropriate metrics were applied to the Company along with qualitative comparable assessments. The indicated value under the market approach was used as the starting aggregate value for the valuation of these performance-based shares. The Company utilized a Monte Carlo simulation method to determine the fair value of the performance-based shares as of the issuance date. The Monte Carlo simulation method takes into consideration the expected timing of the performance milestones, probability of achieving the milestones and estimated per share common stock prices at expected vesting dates. The Company determined that the issuance in February 2014 had a deemed fair value lower than the reassessed fair value of the common stock on the date of issuance based upon the PWERM. Since the stock issuance to the founder is tied to certain performance criteria, the Company reviewed the probability of achieving such criteria at February 20, 2014, September 30, 2014 and September 30, 2015 and determined that it was not probable that the criteria would be met. Therefore, no compensation expense has been recorded for this issuance through September 30, 2015. The Company will continue to reassess at each reporting period whether it is probable that either of the two performance criteria will be met, and if and when either are 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 criteria will actually be met. 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 $61,566. On April 8, 2015, the Company entered into a Second Amendment to Master License Agreement with Ligand, pursuant to which the parties agreed to revise (1) the calculations used to determine the number of securities to be issued to Ligand upon the closing of the IPO, and (2) certain of the royalty percentages payable by the Company to Ligand based on worldwide annual net sales of the products licensed under the Master License Agreement. Further, on April 8, 2015, the Company and Ligand entered into a First Amendment to Loan and Security Agreement with Ligand (the “Loan Amendment”), pursuant to which the parties agreed to amend, among other things, the timing of Ligand’s conversion rights under the Secured Convertible Promissory Note issued to Ligand on May 21, 2014 (the “Ligand Note”) following certain Company transactions. Under the terms of the Loan Amendment, following the consummation of the earlier to occur of (1) a bona fide capital financing transaction or series of financing transactions with one or more financial non-strategic investors resulting in aggregate net proceeds to the Company of at least $20,000,000 and pursuant to which the Company issues shares of its equity securities, (2) a firmly underwritten public offering pursuant to the Securities Act of 1933, as amended, on Form S-1 or Form S-3, or any successor forms, or (3) May 4, 2016 (the one year anniversary of the closing of the IPO), Ligand may elect to convert the Ligand Note into shares of the Company’s common stock and/or cash in an amount equal to 200% of the principal amount of the loan plus all accrued and previously unpaid interest thereon. Additionally, pursuant to the Loan Amendment, Ligand has agreed that it will not, until the earlier of (A) 270 days from the date of conversion of the Ligand Note or (B) April 28, 2016 (one year following the date of the prospectus filed with the SEC relating to the IPO), sell or otherwise transfer or dispose of the shares of common stock issuable upon conversion of the Ligand Note. On May 4, 2015, the Company completed the IPO pursuant to a Registration Statement on Form S-1 that was declared effective on April 28, 2015. 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 $22,080,500 in net proceeds after deducting underwriting discounts, commissions and a non-accountable expense allowance in an aggregate amount of $1,919,500, but before deducting other offering costs and expenses. Costs directly associated with the IPO of $2,980,000 were capitalized and recorded as deferred IPO costs prior to the closing of the IPO. 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 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 $3,312,000, after deducting underwriting discounts and commissions of $288,000, but before deducting other offering costs and expenses. 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 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 20, 2015, and in accordance with the Company’s 2014 Employee Stock Purchase Plan (the “ESPP”), the Company issued 282 shares of its common stock to certain employees. As of September 30, 2015, the Company had 9,783,312 shares issued and outstanding.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	5. 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 reserved for issuance under the 2014 Plan, and 458,331 shares of the Company’s common stock were 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 three and nine months ended September 30, 2015 and 2014, the Company recognized the following stock-based compensation expense: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Stock-based compensation expense by type of award: Stock options $ 373,881 $ — $ 725,572 $ — Restricted stock and restricted stock units 227,712 904 1,348,432 5,355 Total stock-based compensation expense included in expenses $ 601,593 $ 904 $ 2,074,004 $ 5,355 Stock-based compensation expense by line item: Research and development expenses $ 164,125 $ — $ 665,226 $ 2,643 General and administrative expenses 437,468 904 1,408,778 2,712 Total stock-based compensation expense included in expenses $ 601,593 $ 904 $ 2,074,004 $ 5,355 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 September 30, 2015 Unrecognized Net of Estimated Forfeitures Weighted-average Recognition Period (in years) Type of award: Stock options $ 2,023,067 2.80 Restricted stock and restricted stock units $ 2,731,371 2.85 The following table is a summary of restricted shares granted during the nine months ended September 30, 2015 and the year ended December 31, 2014: Shares Weighted- Average Grant Date Fair Value Unvested at December 31, 2013 2,189,583 $ 0.003 Granted 1,000,000 $ 0.17 Vested (1,170,831 ) $ 0.003 Forfeited — $ — Unvested at December 31, 2014 2,018,752 $ 0.08 Granted 462,090 $ 9.49 Vested (702,165 ) $ 1.37 Forfeited — $ — Repurchased (1,005,714 ) $ 0.03 Unvested at September 30, 2015 772,963 $ 4.45 The following table summarizes stock option activity during the nine months ended September 30, 2015: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Options outstanding at December 31, 2014 — $ — — Granted 443,894 $ 8.49 — Exercised — $ — — Cancelled (33,750 ) $ 9.49 — Options outstanding at September 30, 2015 410,144 $ 8.41 9.66 Options exercisable at September 30, 2015 51,500 $ 9.49 9.60 During the nine months ended September 30, 2015, the Company issued an aggregate of 84,000 restricted stock units to certain employees of the Company. There were no restricted stock units issued during the nine months ended September 30, 2014. On October 1, 2015, 105,000 shares of restricted stock were forfeited. Compensation cost 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 nine months ended September 30, 2015 was $6.25. The options outstanding and exercisable at September 30, 2015 had no intrinsic value in the aggregate. As stock-based compensation expense recognized is based on options ultimately expected to vest, the expense has been reduced for estimated forfeitures. The fair value of each employee option grant during the nine months ended September 30, 2015 was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: Nine Months Ended September 30, 2015 Expected volatility 85.2 % Expected term (in years) 6.49 Risk-free interest rate 1.81 % 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 estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates. The Company estimates forfeitures based on its historical experience. Groups of employees that have similar historical forfeiture behavior are considered separately for expense recognition. During the nine months ended September 30, 2015, 282 shares of common stock were issued under the ESPP. The Company issues new shares of common stock on each purchase date under the ESPP. Since the Company had a net operating loss carryforward as of September 30, 2015, no excess tax benefits for the tax deductions related to stock-based awards were recognized in the Statements of Operations.

Representative's Warrant

Representative's Warrant	9 Months Ended
	Sep. 30, 2015
Warrants And Rights Note Disclosure [Abstract]
Representative's Warrant	6. Representative’s Warrant 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 an 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. The representative (or permitted assignees) agreed not to sell, transfer, assign, pledge or hypothecate the warrant or the shares of common stock underlying the warrant, or to engage in any hedging, short sale, derivative, put or call transaction that would result in the effective economic disposition of the warrant or the underlying shares of common stock until October 25, 2015. 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.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2015
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. 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 (the “Premises”). 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 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. Future minimum payments pursuant to the Sublease are as follows: Year Ending December 31: 2015 (Three months remaining) $ 39,474 2016 199,740 2017 247,611 2018 190,337 Total minimum lease payments $ 677,162

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2015
Subsequent Events [Abstract]
Subsequent Events	8. Subsequent Events The Company has evaluated all subsequent events through the filing date of this Quarterly Report on Form 10-Q with the SEC, to ensure that this filing includes appropriate disclosure of events both recognized in the financial statements as of September 30, 2015, and events which occurred subsequent to September 30, 2015 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.

Organization, Liquidity and M14

Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2015
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, first-in-class or best-in-class 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, California.
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”). The accompanying balance sheet as of September 30, 2015, statements of operations for the three and nine months ended September 30, 2015 and 2014 and statements of cash flows for the nine months ended September 30, 2015 and 2014 are unaudited. These unaudited financial statements have been prepared in accordance with the rules and regulations of the United States Securities and Exchange Commission (“SEC”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. These financial statements should be read in conjunction with the audited financial statements and the accompanying notes for the year ended December 31, 2014 contained in the final prospectus filed by the Company with the SEC on April 29, 2015 relating to the Company’s initial public offering (the “IPO”). The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments (consisting of normal recurring adjustments) necessary to state fairly the Company’s financial position as of September 30, 2015 and the results of operations for the three and nine months ended September 30, 2015 and 2014 and cash flows for the nine months ended September 30, 2015 and 2014. The December 31, 2014 balance sheet included herein was derived from the audited financial statements, but does not include all disclosures or notes required by GAAP for complete financial statements. The financial data and other information disclosed in these notes to the financial statements related to the three and nine months ended September 30, 2015 and 2014 are unaudited. Interim results are not necessarily indicative of results for an entire year.
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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements For a discussion of recent accounting pronouncements, please refer to Note 1, “Organization, Liquidity and Management’s Plan, and Summary of Significant Accounting Policies” of the financial statements in the final prospectus filed by the Company with the SEC on April 29, 2015 relating to the IPO. The Company did not adopt any new accounting pronouncements during the nine months ended September 30, 2015 that had a material effect on its condensed financial statements.
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 May 2015, the Company completed the IPO, issuing 3,450,000 shares of its common stock and raising $25,392,500 in net proceeds, including the full exercise of the over-allotment option, and after deducting underwriting discounts, commissions and a non-accountable expense in an aggregate amount of $2,207,500, but before deducting other offering costs and expenses. These additional funds raised in May 2015 alleviate any doubt in regards to the Company’s ability to continue as a going concern over the next 12 months. (See Note 4 regarding proceeds from the IPO received in May 2015.)
Deferred IPO Financing Costs	Deferred IPO Financing Costs Deferred IPO financing costs represent legal, accounting and other direct costs related to the Company’s efforts to raise capital through a public sale of the Company’s common stock. Costs related to the IPO were deferred until the completion of the IPO, at which time they were reclassified to additional paid-in capital as a reduction of the IPO proceeds. Through September 30, 2015, $3,066,136 of offering costs were recorded as a reduction of the proceeds received.
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 to be recognized over the period that any related services are to be provided by the Company. Amounts received for research funding are to be 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 to be recorded as revenue for the gross amount of the reimbursement, and the costs associated with these reimbursements are to be reflected as a component of research and development expense in the statements of operations. Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 605-28, Revenue Recognition – Milestone Method 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 clinical 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. The Company’s historical research and development expenses primarily related to obtaining the option to license compounds and related intellectual property rights from Ligand Pharmaceuticals Incorporated (“Ligand”). In May 2014, the Company entered into a master license agreement with Ligand, as amended (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. Prior to 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 are deemed probable of being met, then the Company will then begin 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 are 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. Income tax positions must meet a more-likely-than-not recognition threshold to be recognized. Income tax positions that previously failed to meet the more-likely-than-not threshold are recognized in the first subsequent financial reporting period in which that threshold is met. Previously recognized tax positions that no longer meet the more-likely-than-not threshold are derecognized in the first subsequent financial reporting period in which that threshold is no longer met.
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: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Historical net loss per share Numerator Net loss attributable to common stockholders $ (4,736,544 ) $ (261,801 ) $ (18,313,025 ) $ (23,273,530 ) Denominator Weighted-average common shares outstanding 9,783,312 6,000,000 8,120,639 5,813,187 Less: Weighted-average shares subject to repurchase (835,832 ) (1,481,561 ) (1,318,470 ) (1,831,040 ) Denominator for basic and diluted net loss per share 8,947,480 4,518,439 6,802,169 3,982,147 Basic and diluted net loss per share $ (0.53 ) $ (0.06 ) $ (2.69 ) $ (5.84 ) 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): Three and Nine Months Ended September 30, 2015 2014 Common stock warrants 82,500 — Restricted stock units 84,000 — Common stock subject to repurchase 772,963 2,295,833 Common stock options 410,144 — Shares issued upon conversion of debt 663,090 — 2,012,697 2,295,833
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.

Organization, Liquidity and M15

Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2015
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: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Historical net loss per share Numerator Net loss attributable to common stockholders $ (4,736,544 ) $ (261,801 ) $ (18,313,025 ) $ (23,273,530 ) Denominator Weighted-average common shares outstanding 9,783,312 6,000,000 8,120,639 5,813,187 Less: Weighted-average shares subject to repurchase (835,832 ) (1,481,561 ) (1,318,470 ) (1,831,040 ) Denominator for basic and diluted net loss per share 8,947,480 4,518,439 6,802,169 3,982,147 Basic and diluted net loss per share $ (0.53 ) $ (0.06 ) $ (2.69 ) $ (5.84 )
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): Three and Nine Months Ended September 30, 2015 2014 Common stock warrants 82,500 — Restricted stock units 84,000 — Common stock subject to repurchase 772,963 2,295,833 Common stock options 410,144 — Shares issued upon conversion of debt 663,090 — 2,012,697 2,295,833

Investments in Marketable Sec16

Investments in Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2015
Investments Debt And Equity Securities [Abstract]
Summary of Investments Classified As Available-For-Sale Securities	Investments classified as available-for-sale at September 30, 2015 consisted of the following: Amortized Cost Gross Unrealized Gains (1) Gross Unrealized Losses (1) Aggregate Estimated Fair Value Money market funds (2) 1,269,047 — — 1,269,047 Certificates of deposit (3) 7,089,727 — — 7,089,727 Corporate debt securities (4) 8,264,628 975 (5,823 ) 8,259,780 $ 16,623,402 $ 975 $ (5,823 ) $ 16,618,554 (1) Unrealized gains and losses on available-for-sale securities are included as a component of comprehensive loss. At September 30, 2015, there were 12 securities in an unrealized loss position. These unrealized losses were less than $2,000 individually and $6,000 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) All money market funds are classified as cash equivalents. (3) At September 30, 2015, none of these securities were classified as cash and cash equivalents on the Company’s balance sheet and $249,348 of these securities were scheduled to mature outside of one year. (4) At September 30, 2015, none of these securities were classified as cash and cash equivalents on the Company’s balance sheet and $0 of these securities were scheduled to mature outside of one year.

Fair Value of Financial Instr17

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements of Financial Assets and Liabilities Valued Using Observable Inputs	Fair Value Measurements at September 30, 2015 Total Level 1 Level 2 Level 3 Financial assets carried at fair value: Cash equivalents: Money market funds $ 1,269,047 $ 1,269,047 $ — $ — Short-term investments Certificates of deposit 7,089,727 7,089,727 — — Corporate debt securities, available-for-sale 8,259,780 — 8,259,780 — Total financial assets $ 16,618,554 $ 8,358,773 $ 8,259,780 $ — Financial liabilities carried at fair value: Debt conversion feature - current $ 2,154,062 $ — $ — $ 2,154,062 Total financial liabilities $ 2,154,062 $ — $ — $ 2,154,062 Fair Value Measurements at December 31, 2014 Total Level 1 Level 2 Level 3 Financial liabilities carried at fair value: Accrued license fees $ 19,865,863 $ — $ — $ 19,865,863 Debt conversion feature – current 58,742 — — 58,742 Debt conversion feature – long-term 1,390,469 — — 1,390,469 Total financial liabilities $ 21,315,074 $ — $ — $ 21,315,074
Summary of Changes in Accrued License Fee and Debt Conversion Feature Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs	The table below presents a summary of changes in the Company’s accrued license fee and debt conversion feature liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three and nine months ended September 30, 2015 and 2014: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Accrued license fees: Beginning balance $ — $ 22,128,979 $ 19,865,863 $ — Additions — 517,960 — 21,687,576 Adjustments resulting from changes in fair value recognized in earnings — (695,251 ) 9,381,848 264,112 Issuance of shares of common stock — — (29,247,711 ) — Ending balance $ — $ 21,951,688 $ — $ 21,951,688 Debt conversion feature: Beginning balance $ 1,956,566 $ 1,063,543 $ 1,449,211 $ 71,655 Additions — 508,105 — 1,492,072 Adjustments resulting from changes in fair value recognized in earnings 197,496 (413,703 ) 826,637 (405,782 ) Issuance of shares of common stock — — (121,786 ) — Ending balance $ 2,154,062 $ 1,157,945 $ 2,154,062 $ 1,157,945
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 Unobservable Input Range Assets Liabilities Valuation Technique(s) Accrued license fees: December 31, 2014 $ — $ 19,865,863 Probability weighted expected return model Probability weightings assigned to each scenario 30% to 40% Time assumptions to liquidation events 4/30/2015- 3/31/2017 Discount rates 12% to 60% Debt conversion feature liability September 30, 2015 $ — $ 2,154,062 Discounted cash flow model Timing of the events 5/21/2016 Probabilities of Occurrence 100% Discount rate 37.5% December 31, 2014 $ — $ 1,449,211 Discounted cash flow model Timing of the events 3/31/2015 to 6/30/2015 Probabilities of Occurrence 30% to 40% Discount rate 37.5%

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock-based Compensation Expense Recognized	During the three and nine months ended September 30, 2015 and 2014, the Company recognized the following stock-based compensation expense: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Stock-based compensation expense by type of award: Stock options $ 373,881 $ — $ 725,572 $ — Restricted stock and restricted stock units 227,712 904 1,348,432 5,355 Total stock-based compensation expense included in expenses $ 601,593 $ 904 $ 2,074,004 $ 5,355 Stock-based compensation expense by line item: Research and development expenses $ 164,125 $ — $ 665,226 $ 2,643 General and administrative expenses 437,468 904 1,408,778 2,712 Total stock-based compensation expense included in expenses $ 601,593 $ 904 $ 2,074,004 $ 5,355
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 September 30, 2015 Unrecognized Net of Estimated Forfeitures Weighted-average Recognition Period (in years) Type of award: Stock options $ 2,023,067 2.80 Restricted stock and restricted stock units $ 2,731,371 2.85
Summary of Restricted Shares Granted	The following table is a summary of restricted shares granted during the nine months ended September 30, 2015 and the year ended December 31, 2014: Shares Weighted- Average Grant Date Fair Value Unvested at December 31, 2013 2,189,583 $ 0.003 Granted 1,000,000 $ 0.17 Vested (1,170,831 ) $ 0.003 Forfeited — $ — Unvested at December 31, 2014 2,018,752 $ 0.08 Granted 462,090 $ 9.49 Vested (702,165 ) $ 1.37 Forfeited — $ — Repurchased (1,005,714 ) $ 0.03 Unvested at September 30, 2015 772,963 $ 4.45
Summary of Stock Option Activity	The following table summarizes stock option activity during the nine months ended September 30, 2015: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Options outstanding at December 31, 2014 — $ — — Granted 443,894 $ 8.49 — Exercised — $ — — Cancelled (33,750 ) $ 9.49 — Options outstanding at September 30, 2015 410,144 $ 8.41 9.66 Options exercisable at September 30, 2015 51,500 $ 9.49 9.60
Schedule of Weighted Average Assumptions using Black-Scholes Option Pricing Model	The fair value of each employee option grant during the nine months ended September 30, 2015 was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: Nine Months Ended September 30, 2015 Expected volatility 85.2 % Expected term (in years) 6.49 Risk-free interest rate 1.81 % Expected dividend yield 0 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2015
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: 2015 (Three months remaining) $ 39,474 2016 199,740 2017 247,611 2018 190,337 Total minimum lease payments $ 677,162

Organization, Liquidity and M20

Organization, Liquidity and Management's Plan, and Summary of Significant Accounting Policies - Additional Information (Detail)	May. 28, 2015USD ($)	May. 04, 2015USD ($)shares	Apr. 28, 2015USD ($)shares	May. 31, 2015USD ($)shares	Sep. 30, 2015USD ($)Segment
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
Offering costs recorded as reduction of proceeds received					$ 3,066,136
Number of operating segment | Segment					1
IPO [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Common stock sold | shares		3,427,859	3,000,000	3,450,000
Net proceeds after deducting underwriting discounts and commissions	$ 3,312,000		$ 22,080,500	$ 25,392,500
Underwriting discounts, commissions and a non-accountable expense		$ 1,919,500		$ 2,207,500

Organization, Liquidity and M21

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 ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator
Net loss attributable to common stockholders	$ (4,736,544)	$ (261,801)	$ (18,313,025)	$ (23,273,530)
Denominator
Weighted-average common shares outstanding	9,783,312	6,000,000	8,120,639	5,813,187
Less: Weighted-average shares subject to repurchase	(835,832)	(1,481,561)	(1,318,470)	(1,831,040)
Denominator for basic and diluted net loss per share	8,947,480	4,518,439	6,802,169	3,982,147
Basic and diluted net loss per share	$ (0.53)	$ (0.06)	$ (2.69)	$ (5.84)

Organization, Liquidity and M22

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	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded in calculation of diluted net loss per share	2,012,697	2,295,833
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	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	84,000
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	772,963	2,295,833
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	410,144
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	663,090

Investments in Marketable Sec23

Investments in Marketable Securities - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Available For Sale Securities [Abstract]
Investments classified as available-for-sale	$ 16,618,554	$ 16,618,554	$ 0
Proceeds from sales of available-for-sale securities	$ 0	$ 0

Investments in Marketable Sec24

Investments in Marketable Securities - Summary of Investments Classified As Available-For-Sale Securities (Detail) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 16,623,402
Gross Unrealized Gains	975
Gross Unrealized Losses	(5,823)
Aggregate Estimated Fair Value	16,618,554	$ 0
Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,269,047
Aggregate Estimated Fair Value	1,269,047
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,089,727
Aggregate Estimated Fair Value	7,089,727
Corporate debt securities, available-for-sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,264,628
Gross Unrealized Gains	975
Gross Unrealized Losses	(5,823)
Aggregate Estimated Fair Value	$ 8,259,780

Investments in Marketable Sec25

Investments in Marketable Securities - Summary of Investments Classified As Available-For-Sale Securities (Parenthetical) (Detail)	Sep. 30, 2015USD ($)Security
Schedule of Available-for-sale Securities [Line Items]
Number of securities in unrealized loss position | Security	12
Investments classified as available-for-sale, current	$ 15,349,507
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments classified as available-for-sale, noncurrent	249,348
Corporate debt securities, available-for-sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments classified as available-for-sale, noncurrent	0
Cash equivalents [Member] | Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments classified as available-for-sale, current	0
Cash equivalents [Member] | Corporate debt securities, available-for-sale [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments classified as available-for-sale, current	0
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
unrealized losses, individually	2,000
unrealized losses, aggregate	$ 6,000

Fair Value of Financial Instr26

Fair Value of Financial Instruments - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net proceeds from issuance of capital stock	$ 25,392,500
Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net proceeds from issuance of capital stock	$ 5,000,000

Fair Value of Financial Instr27

Fair Value of Financial Instruments - Fair Value Measurements of Financial Assets and Liabilities Valued Using Observable Inputs (Detail) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Financial assets carried at fair value:
Short-term investments, available for sale	$ 16,618,554	$ 0
Total financial assets	16,618,554
Financial liabilities carried at fair value:
Accrued license fees		19,865,863
Debt conversion feature – current	2,154,062	58,742
Debt conversion feature – long-term		1,390,469
Total financial liabilities	2,154,062	21,315,074
Level 1 [Member]
Financial assets carried at fair value:
Total financial assets	8,358,773
Level 2 [Member]
Financial assets carried at fair value:
Total financial assets	8,259,780
Level 3 [Member]
Financial liabilities carried at fair value:
Accrued license fees		19,865,863
Debt conversion feature – current	2,154,062	58,742
Debt conversion feature – long-term		1,390,469
Total financial liabilities	2,154,062	$ 21,315,074
Money market funds [Member]
Financial assets carried at fair value:
Cash and cash equivalents, fair value disclosure	1,269,047
Money market funds [Member] | Level 1 [Member]
Financial assets carried at fair value:
Cash and cash equivalents, fair value disclosure	1,269,047
Certificates of deposit [Member]
Financial assets carried at fair value:
Short-term investments, available for sale	7,089,727
Certificates of deposit [Member] | Level 1 [Member]
Financial assets carried at fair value:
Short-term investments, available for sale	7,089,727
Corporate debt securities, available-for-sale [Member]
Financial assets carried at fair value:
Short-term investments, available for sale	8,259,780
Corporate debt securities, available-for-sale [Member] | Level 2 [Member]
Financial assets carried at fair value:
Short-term investments, available for sale	$ 8,259,780

Fair Value of Financial Instr28

Fair Value of Financial Instruments - Summary of Changes in Accrued License Fee and Debt Conversion Feature Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accrued License Fees [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		$ 22,128,979	$ 19,865,863
Additions		517,960		$ 21,687,576
Adjustments resulting from changes in fair value recognized in earnings		(695,251)	9,381,848	264,112
Issuance of shares of common stock			(29,247,711)
Ending balance		21,951,688		21,951,688
Debt Conversion Feature Liability [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 1,956,566	1,063,543	1,449,211	71,655
Additions		508,105		1,492,072
Adjustments resulting from changes in fair value recognized in earnings	197,496	(413,703)	826,637	(405,782)
Issuance of shares of common stock			(121,786)
Ending balance	$ 2,154,062	$ 1,157,945	$ 2,154,062	$ 1,157,945

Fair Value of Financial Instr29

Fair Value of Financial Instruments - Schedule of Valuation Techniques and Significant Unobservable Inputs Used to Determine Fair Value of Significant Level 3 Liabilities (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Jun. 30, 2015	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Accrued License Fees [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Liabilities		$ 19,865,863		$ 21,951,688	$ 22,128,979
Debt Conversion Feature Liability [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Liabilities	$ 2,154,062	1,449,211	$ 1,956,566	$ 1,157,945	$ 1,063,543	$ 71,655
Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Assets		0
Fair Value, Liabilities		$ 1,449,211
Valuation Technique(s)	Discounted cash flow model
Level 3 [Member] | Discounted Cash Flow Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Probabilities of Occurrence Discount rate, Range		37.50%
Level 3 [Member] | Minimum [Member] | Probability Weighted Expected Return Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate, Range		12.00%
Level 3 [Member] | Minimum [Member] | Discounted Cash Flow Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Timing of the events, Range		Mar. 31, 2015
Probabilities of Occurrence Discount rate, Range		30.00%
Level 3 [Member] | Maximum [Member] | Probability Weighted Expected Return Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate, Range		60.00%
Level 3 [Member] | Maximum [Member] | Discounted Cash Flow Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Timing of the events, Range		Jun. 30, 2015
Probabilities of Occurrence Discount rate, Range		40.00%
Level 3 [Member] | Accrued License Fees [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Assets		$ 0
Fair Value, Liabilities		$ 19,865,863
Valuation Technique(s)	Probability weighted expected return model
Level 3 [Member] | Accrued License Fees [Member] | Minimum [Member] | Probability Weighted Expected Return Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Probability weightings assigned to each scenario, Range		30.00%
Time assumptions to liquidation events, Range		Apr. 30, 2015
Level 3 [Member] | Accrued License Fees [Member] | Maximum [Member] | Probability Weighted Expected Return Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Probability weightings assigned to each scenario, Range		40.00%
Time assumptions to liquidation events, Range		Mar. 31, 2017
Level 3 [Member] | Debt Conversion Feature Liability [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Assets	$ 0
Fair Value, Liabilities	$ 2,154,062
Valuation Technique(s)	Discounted cash flow model
Level 3 [Member] | Debt Conversion Feature Liability [Member] | Discounted Cash Flow Model [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate, Range	37.50%
Level 3 [Member] | Debt Conversion Feature Liability [Member] | Minimum [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%

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) - Additional Information (Detail)	May. 28, 2015USD ($)shares	May. 26, 2015$ / sharesshares	May. 20, 2015shares	May. 04, 2015USD ($)$ / sharesshares	Apr. 28, 2015USD ($)$ / sharesshares	Apr. 08, 2015USD ($)	May. 31, 2015USD ($)$ / sharesshares	Feb. 28, 2014Tranche$ / sharesshares	Sep. 30, 2015USD ($)shares	Sep. 30, 2015USD ($)shares	Sep. 30, 2014USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)shares	Feb. 20, 2014USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
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 | $									$ 61,566	$ 61,566				$ 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
Compensation expense | $									0	$ 2,074,004	$ 5,355
Anniversary date of closing of IPO										May 4, 2016
Granted, Shares										443,894
Accrued license fees | $													$ 19,865,863
Convertible notes payable, current | $									1,911,024	$ 1,911,024			304,274
Convertible notes payable, interest | $									$ 152,361	$ 152,361			$ 77,222
Shares issued under ESPP			282							282
Common stock, shares issued									9,783,312	9,783,312			6,000,000
Common stock, shares outstanding									9,783,312	9,783,312			6,000,000
Non-employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Shares					83,144
IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchase of common stock from stockholders, per share | $ / shares				$ 0.00001
Anniversary date of closing of IPO					May 4, 2015
Common stock sold				3,427,859	3,000,000		3,450,000
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
Net proceeds after deducting underwriting discounts and commissions | $	$ 3,312,000				$ 22,080,500		$ 25,392,500
Underwriting discounts, commissions and a non-accountable expense | $				$ 1,919,500			$ 2,207,500
Deferred IPO costs | $				$ 2,980,000
Repurchase of common stock				3,802,859
Repurchase of common stock from stockholders, value | $				$ 38
Additional shares purchase under underwriting agreement		450,000
Underwriting discounts and commission | $	$ 288,000
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
IPO [Member] | Accrued License Fees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued license fees converted into common stock, shares issued				3,427,859
IPO [Member] | Employees, Directors and Consultants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock sold										422,879
Granted, Shares										206,000
IPO [Member] | Ligand And Metabasis Therapeutics Inc [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock sold	228,105
Loan Amendment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Note conversion, principal amount of loan plus all accrued and previously unpaid interest						200.00%
Note conversion, description										Ligand has agreed that it will not, until the earlier of (A) 270 days from the date of conversion of the Ligand Note or (B) April 28, 2016 (one year following the date of the prospectus filed with the SEC relating to the IPO), sell or otherwise transfer or dispose of the shares of common stock issuable upon conversion of the Ligand Note.
Minimum [Member] | Loan Amendment [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate net proceeds from issue of equity securities | $						$ 20,000,000
Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of common stock for issuance in exchange for future services from founders								500,000
Remaining number of repurchased shares							183,095
Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [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)	Oct. 01, 2015shares	Sep. 30, 2015USD ($)shares	May. 20, 2015shares	Sep. 30, 2015USD ($)Period$ / sharesshares	Sep. 30, 2014shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of stock options granted to employees | $ / shares				$ 6.25
Options outstanding, Aggregate Intrinsic Value | $		$ 0		$ 0
Options exercisable, Aggregate Intrinsic Value | $		0		$ 0
Issuance of restricted stock				84,000	0
Shares issued under ESPP			282	282
Excess tax benefit from stock-based awards | $		$ 0
Restricted Stock [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares forfeited	105,000
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		1,527,770
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%
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance		458,331		458,331
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%
The 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		1,527,770
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance		458,331		458,331

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-based Compensation Expense Recognized (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	$ 601,593	$ 904	$ 2,074,004	$ 5,355
Research and development expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	164,125		665,226	2,643
General and administrative expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	437,468	904	1,408,778	2,712
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense included in expenses	373,881		725,572
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	$ 227,712	$ 904	$ 1,348,432	$ 5,355

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 ($)	9 Months Ended
	Sep. 30, 2015	Feb. 20, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense, Net of Estimated Forfeitures	$ 61,566	$ 168,000
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense, Net of Estimated Forfeitures	$ 2,023,067
Weighted-average Recognition Period	2 years 9 months 18 days
Restricted stock and restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Expense, Net of Estimated Forfeitures	$ 2,731,371
Weighted-average Recognition Period	2 years 10 months 6 days

Stock-Based Compensation - Su34

Stock-Based Compensation - Summary of Restricted Shares Granted (Detail) - Restricted stock units [Member] - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Unvested, Beginning balance	2,018,752	2,189,583
Shares, Granted	462,090	1,000,000
Shares, Vested	(702,165)	(1,170,831)
Shares, Forfeited	0	0
Shares, Repurchased	(1,005,714)
Shares, Unvested, Ending balance	772,963	2,018,752
Weighted-Average Grant Date Fair Value, Unvested, Beginning balance	$ 0.08	$ 0.003
Weighted-Average Grant Date Fair Value, Granted	9.49	0.17
Weighted-Average Grant Date Fair Value, Vested	1.37	0.003
Weighted-Average Grant Date Fair Value, Forfeited	0	0
Weighted-Average Grant Date Fair Value, Repurchased	0.03
Weighted-Average Grant Date Fair Value, Unvested, Ending balance	$ 4.45	$ 0.08

Stock-Based Compensation - Su35

Stock-Based Compensation - Summary of Stock Option Activity (Detail)	9 Months Ended
	Sep. 30, 2015$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Granted, Shares	443,894
Exercised, Shares	0
Cancelled, Shares	(33,750)
Outstanding ending balance, Shares	410,144
Options exercisable, Shares	51,500
Granted, Weighted- Average Exercise Price | $ / shares	$ 8.49
Exercised, Weighted- Average Exercise Price | $ / shares	0
Cancelled, Weighted- Average Exercise Price | $ / shares	9.49
Outstanding ending balance, Weighted- Average Exercise Price | $ / shares	8.41
Options exercisable, Weighted- Average Exercise Price | $ / shares	$ 9.49
Options outstanding, Weighted Average Remaining Contractual Term	9 years 7 months 28 days
Options exercisable, Weighted Average Remaining Contractual Term	9 years 7 months 6 days

Stock-Based Compensation - Sc36

Stock-Based Compensation - Schedule of Weighted Average Assumptions using Black-Scholes Option Pricing Model (Detail)	9 Months Ended
	Sep. 30, 2015
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]
Expected volatility	85.20%
Expected term (in years)	6 years 5 months 27 days
Risk-free interest rate	1.81%
Expected dividend yield	0.00%

Representative's Warrant - Addi

Representative's Warrant - Additional Information (Detail) - $ / shares	May. 04, 2015	Sep. 30, 2015
Class of Warrant or Right [Line Items]
Exercise price of warrant		$ 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. The representative (or permitted assignees) agreed not to sell, transfer, assign, pledge or hypothecate the warrant or the shares of common stock underlying the warrant, or to engage in any hedging, short sale, derivative, put or call transaction that would result in the effective economic disposition of the warrant or the underlying shares of common stock until October 25, 2015. 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
Common stock warrants [Member]
Class of Warrant or Right [Line Items]
Issuance of shares of common stock	82,500

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Jul. 07, 2015ft²
Commitments And Contingencies Disclosure [Abstract]
Area of subleased premises	7,049

Commitments and Contingencies39

Commitments and Contingencies - Summary of Future Minimum Payments for Sublease (Detail)	Sep. 30, 2015USD ($)
Operating Leases, Future Minimum Payments [Abstract]
2015 (Three months remaining)	$ 39,474
2,016	199,740
2,017	247,611
2,018	190,337
Total minimum lease payments	$ 677,162