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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2018	Nov. 07, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Trading Symbol	ARPO
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Registrant Name	Aerpio Pharmaceuticals, Inc.
Entity Central Index Key	0001422142
Entity Common Stock, Shares Outstanding		40,588,004

Condensed Consolidated Balance Sheets (Unaudited) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 68,807,267	$ 20,264,109
Prepaid research and development contracts	337,192	313,140
Other current assets	895,091	322,221
Total current assets	70,039,550	20,899,470
Furniture and equipment, net	101,291	107,223
Deposits	20,960	20,960
Total assets	70,161,801	21,027,653
Current liabilities:
Accounts payable and accrued expenses	3,644,685	3,592,164
Total current liabilities	3,644,685	3,592,164
Commitments and contingencies (Note 10)
Stockholders’ equity:
Common stock, $0.0001 par value per share; 300,000,000 shares authorized and 40,588,004 and 27,070,038 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively.	4,059	2,707
Additional paid-in capital	176,953,759	125,995,438
Accumulated deficit	(110,440,702)	(108,562,656)
Total stockholders’ equity	66,517,116	17,435,489
Total liabilities and stockholders’ equity	$ 70,161,801	$ 21,027,653

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	40,588,004	27,070,038
Common stock, shares outstanding	40,588,004	27,070,038

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
License revenue, and other	$ 18,821,953		$ 20,155,286
Type of Revenue [Extensible List]	arpo:LicenseRevenueAndOtherMember		arpo:LicenseRevenueAndOtherMember
Operating expenses
Research and development	$ 4,346,381	$ 2,942,170	$ 12,604,125	$ 8,366,869
General and administrative	3,277,535	1,814,068	9,866,227	6,732,816
Total operating expenses	7,623,916	4,756,238	22,470,352	15,099,685
Income (loss) from operations	11,198,037	(4,756,238)	(2,315,066)	(15,099,685)
Grant income	6,394	46,824	6,394	93,720
Interest income (expense), net	333,047	59,847	430,626	(159,612)
Total other income (expense)	339,441	106,671	437,020	(65,892)
Net and comprehensive income (loss)	11,537,478	(4,649,567)	(1,878,046)	(15,165,577)
Reconciliation of net income (loss) attributable to common stockholders:
Net and comprehensive income (loss)	11,537,478	(4,649,567)	(1,878,046)	(15,165,577)
Adjustment of redeemable convertible preferred stock to redemption value				(943,297)
Net income (loss) attributable to common stockholders	$ 11,537,478	$ (4,649,567)	$ (1,878,046)	$ (16,108,874)
Net income (loss) per share
Basic and diluted	$ 0.28	$ (0.17)	$ (0.06)	$ (0.81)
Weighted average number of common shares used in computing net income (loss) per share
Basic	40,527,722	26,926,673	31,687,434	19,889,984
Diluted	40,961,620	26,926,673	31,687,434	19,889,984

Condensed Consolidated Statement of Stockholders' Equity - 9 months ended Sep. 30, 2018 - USD ($)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2017	$ 17,435,489	$ 2,707	$ 125,995,438	$ (108,562,656)
Balance, Shares at Dec. 31, 2017		27,070,038
Issuance of restricted stock		$ 6	(6)
Issuance of restricted stock, Shares		60,000
Issuance of common stock upon exercise of stock options	$ 76,756	$ 5	76,751
Issuance of common stock upon exercise of stock options, Shares	52,099	52,099
Issuance of common stock, net of issuance costs of $3,502,543	$ 48,119,027	$ 1,341	48,117,686
Issuance of common stock, net of issuance costs, Shares		13,408,200
Forfeiture of restricted stock, Shares		(2,333)
Share-based compensation expense	2,763,890		2,763,890
Net and comprehensive loss	(1,878,046)			(1,878,046)
Balance at Sep. 30, 2018	$ 66,517,116	$ 4,059	$ 176,953,759	$ (110,440,702)
Balance, Shares at Sep. 30, 2018		40,588,004

Condensed Consolidated Statement of Stockholders' Equity (Parenthetical) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Statement Of Stockholders Equity [Abstract]
Payments of stock issuance cost	$ 3,502,543	$ 3,084,385

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities:
Net and comprehensive loss	$ (1,878,046)	$ (15,165,577)
Adjustments to reconcile net and comprehensive loss to net cash provided by (used in) operating activities:
Depreciation	35,312	39,269
Stock-based compensation	2,763,890	394,268
Amortization of debt issuance costs		75,561
Interest expense related to convertible note conversion		204,929
Changes in operating assets and liabilities:
Prepaid research and development contracts	(24,052)	238,658
Other current assets	(572,870)	(656,896)
Accounts payable and other current liabilities	52,521	598,706
Net cash provided by (used in) operating activities	376,755	(14,271,082)
Investing activities:
Purchase of furniture and equipment	(29,380)	(6,547)
Net cash used in investing activities	(29,380)	(6,547)
Financing activities:
Proceeds from exercise of stock options	76,756	36,101
Proceeds from issuances of convertible notes		297,354
Proceeds from sale of common stock	51,621,570	40,247,775
Cash paid in connection with the sale of common stock	(3,502,543)	(3,084,385)
Net cash provided by financing activities	48,195,783	37,496,845
Net increase in cash and cash equivalents	48,543,158	23,219,216
Cash and cash equivalents at beginning of year	20,264,109	1,609,694
Cash and cash equivalents, nine months ended	$ 68,807,267	24,828,910
Non-cash financing activities
Conversion of redeemable convertible preferred stock into common stock		74,701,187
Conversion of convertible notes and accrued interest into common stock		13,447,934
Accretion of redeemable convertible preferred stock to redemption value		$ 943,297

Nature of Organization and Operations	9 Months Ended
Nature of Organization and Operations	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Organization and Operations	1. Nature of Organization and Operations Aerpio Pharmaceuticals, Inc. (the “Company”) is a biopharmaceutical company focused on advancing first-in-class treatments for ocular disease. The Company’s lead product candidate, AKB-9778, a small molecule activator of the Tie2 pathway, is being developed for the treatment of non-proliferative diabetic retinopathy, or NPDR, a disease characterized by progressive compromise of blood vessels in the back of the eye. The Company was incorporated as Zeta Acquisition Corp. II (“Zeta”) in the State of Delaware on November 16, 2007. Prior to the Merger, (as defined below), Zeta was a “shell company” (as defined in Rule 12b-2 of the Securities Exchange Act of 1934, as amended). On March 3, 2017, the Company’s Board of Directors, and on March 10, 2017, the Company’s pre-Merger (as defined below) stockholders, approved an amended and restated certificate of incorporation, which, among other things, increased authorized capital stock from 100,000,000 shares of common stock, par value $0.0001 per share, and 10,000,000 shares of preferred stock, par value $0.0001 per share, to 300,000,000 shares of common stock, par value $0.0001 per share, and 10,000,000 shares of preferred stock, par value $0.0001 per share. On March 15, 2017, Zeta changed its name to Aerpio Pharmaceuticals, Inc. and its wholly-owned subsidiary, Aerpio Acquisition Corp., a corporation formed in the State of Delaware on March 3, 2017, merged with and into Aerpio Therapeutics, Inc., (“Aerpio”), (the “Merger”), a corporation incorporated on November 17, 2011 in the State of Delaware. Pursuant to the Merger, Aerpio remained as the surviving corporation and became the Company’s wholly-owned subsidiary. At the effective time of the Merger, the shares of Aerpio’s (i) common stock issued and outstanding immediately prior to the closing of the Merger (including restricted common stock, whether vested or unvested, issued under the Aerpio’s 2011 Equity Incentive Plan), and (ii) redeemable convertible preferred stock issued and outstanding immediately prior to the closing of the Merger, were converted into shares of the Company’s common stock. In addition, immediately prior to the Merger, the outstanding amounts under certain senior secured convertible notes issued by Aerpio to its pre-Merger noteholders were converted into shares of Aerpio’s preferred stock, which were then converted to shares of Aerpio’s common stock and subsequently were converted into shares of the Company’s common stock, together with the other shares of the Aerpio’s common stock described above. In addition, pursuant to the Merger Agreement options to purchase shares of Aerpio’s common stock issued and outstanding immediately prior to the closing of the Merger were assumed and converted into options to purchase shares of the Company’s common stock. All the outstanding capital stock of Aerpio was converted into shares of the Company’s common stock on a 2.3336572:1 basis. As a result of the Merger, the Company acquired the business of Aerpio and will continue the existing business operations of Aerpio as a public reporting company under the name Aerpio Pharmaceuticals, Inc. Immediately after the Merger, on March 15, 2017, Aerpio converted into a Delaware limited liability company (the “Conversion”). Immediately following the Conversion, the pre-Merger stockholders of Zeta surrendered for cancellation 4,000,000 of the 5,000,000 shares of the outstanding common stock of Zeta, (the “Share Cancellation”). Following the Share Cancellation, on March 15, 2017, the Company closed a private placement offering (the “2017 Offering”) of 8,049,555 shares of the Company’s common stock, at a purchase price of $5.00 per share, for net proceeds of $37.2 million and the issuance of warrants with a term of three years, to purchase 317,562 shares of the Company’s common stock at an exercise price of $5.00 per share. The Merger was treated as a recapitalization and reverse acquisition for financial reporting purposes. The Company is the legal acquirer of Aerpio in the transaction. However, Aerpio is considered the acquiring company for accounting purposes since (i) former Aerpio stockholders own in excess of 50% of the combined enterprise on a fully diluted basis immediately following the Merger and 2017 Offering, and (ii) all members of the Company’s executive management and Board of Directors are from Aerpio. In accordance with “reverse merger” or “reverse acquisition” accounting treatment, the unaudited condensed consolidated financial statements for the periods ended September 30, 2018 and 2017, include the accounts of the Company and its wholly owned subsidiary, Aerpio Therapeutics, LLC. On June 28, 2018, the Company closed an underwritten public offering for the sale of 11,688,000 shares of its common stock, and subsequently on July 2, 2018, the Company closed on the sale of an additional 1,720,200 shares of its common stock, pursuant to the underwriters’ partial exercise of their option to purchase additional shares of common stock (the “2018 Offering”). In the aggregate, the Company received net proceeds of approximately $ 48.1 million from the 2018 Offering after a deduction of $3.5 million related to underwriting discounts and commissions and offering expenses paid in conjunction with the 2018 Offering. On June 24, 2018, the Company entered into a License Agreement (the “Agreement”) with a wholly-owned subsidiary of Gossamer Bio, Inc., GB004, Inc. (collectively “Gossamer”), under which the Company granted Gossamer an exclusive, sublicensable license to develop and commercialize AKB-4924 and other structurally related products worldwide, with initial development expected in the indications of induction and maintenance in ulcerative colitis and Crohn’s Disease. The Company’s operations to date have been limited to organizing and staffing the Company, business planning, raising capital, acquiring and developing its technology, identifying potential product candidates, and undertaking preclinical and clinical studies. The Company’s revenue to date has been primarily limited to license revenue from Gossamer. Future revenue is dependent on the terms of the Agreement. The Company’s product candidates are subject to long development cycles, and there is no assurance the Company will be able to successfully develop, obtain regulatory approval for, or market its product candidates. The Company is subject to a number of risks similar to other life science companies in the current stage of its life cycle including, but not limited to, the need to obtain adequate additional funding, possible failure of preclinical testing or clinical trials, the need to obtain marketing approval for its product candidates, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of any of the Company’s products that are approved, and protection of proprietary technology. If the Company does not successfully commercialize any of its products or mitigate any of these other risks, it will be unable to generate revenue or achieve profitability.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The unaudited condensed consolidated financial statements have been prepared in accordance with U.S. Securities and Exchange Commission (“SEC”) regulations and include all of the information and disclosures required by U.S. generally accepted accounting principles ("U.S. GAAP" or "GAAP") for interim financial reporting, and, in the opinion of management include all adjustments necessary for a fair presentation of the results of operations, financial position, changes in stockholders’ equity and cash flows for each period presented. All adjustments are of a normal and recurring in nature. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements of the Company for the year ended December 31, 2017, included in the Annual Report on Form 10-K filed with the SEC on March 15, 2018. The results of operations for the interim periods are not necessarily indicative of results of operations for a full year. The Company’s condensed consolidated financial statements are stated in U.S. Dollars.

Reclassification

Certain prior year balances within the condensed consolidated statement of cash flows were reclassified to conform with current period presentation. As a result of the current year reclassification, there were no changes in any subtotals of the condensed consolidated statement of cash flows.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment, which is the business of developing and commercializing proprietary therapeutics. All the assets and operations of the Company’s sole operating segment are located in the United States.

Use of Estimates

The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results may differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls and in developing the estimates and assumptions used in the preparation of these condensed consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Estimates are used in the following areas, among others: grant date fair value of the Company’s stock-based awards, accrued expenses, revenue recognition and income taxes.

The Company’s results can also be affected by economic, political, legislative, regulatory, and legal actions. Economic conditions, such as recessionary trends, inflation, interest and monetary exchange rates, government fiscal policies, and changes in the prices of research studies, can have a significant effect on operations. While the Company maintains reserves for anticipated liabilities and carries various levels of insurance, the Company could be affected by civil, criminal, regulatory or administrative actions, claims or proceedings.

Cash and Cash Equivalents

Cash and cash equivalents consist of all cash on hand, deposits and funds invested in short-term investments with original maturities of three months or less at the time of purchase. The Company may maintain balances with its banks in excess of federally insured limits.

Revenue Recognition

At the inception of an arrangement, the Company evaluates if a counterparty to a contract is a customer, if the arrangement is within the scope of revenue from contracts with customers guidance and the term of the contract. The Company recognizes revenue when its customer obtains control of promised goods or services in a contract for an amount that reflects the consideration the Company expects to receive in exchange for those goods or services. For contracts with customers, the Company applies the following five-step model in order to determine this amount: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. As part of the accounting for contracts with customers, the Company must develop assumptions that require judgment to determine the standalone selling price of each performance obligation identified in the contract. The Company then allocates the total transaction price to each performance obligation based on the estimated standalone selling prices of each performance obligation. The Company recognizes the amount of the transaction price as revenue that is allocated to the respective performance obligation when the performance obligation is satisfied or as it is satisfied.

The Company enters into collaboration arrangements, under which it licenses certain rights to its intellectual property to third parties. The terms of these agreements may include payment to the Company of one or more of the following: nonrefundable upfront license fees; development, sale and commercial milestone payments and royalties on net sales of licensed products. Each of these types of payments are classified as license revenue except for revenue from royalties on net sales of licensed products, which are classified as royalty revenue.

For each collaboration agreement that results in revenues, the Company identifies all material promised goods and services, which may include a license to intellectual property, research and development activities and/or transition activities. Promised goods or services are considered to be separate performance obligations if they are distinct. In order to determine the transaction price to be allocated to each performance obligation, in addition to any upfront payment, the Company estimates the amount of variable consideration at the outset of the contract either utilizing the expected value or most likely amount method, depending on the facts and circumstances relative to the contract. The Company constrains (reduces) the estimates of variable consideration such that it is probable that a significant reversal of previously recognized revenue will not occur throughout the life of the contract. When determining if variable consideration should be constrained, management considers whether there are factors outside the Company’s control that could result in a significant reversal of revenue. In making these assessments, the Company considers the likelihood and magnitude of a potential reversal of revenue. These estimates are re-assessed each reporting period as required.

Once the estimated transaction price is established, amounts are allocated to the performance obligations that have been identified. The transaction price is generally allocated to each separate performance obligation on a relative standalone selling price basis. The Company must develop assumptions that require judgment to determine the standalone selling price (SSP) in order to account for these agreements. To determine the standalone selling price the Company’s assumptions may include (i) assumptions regarding the probability of obtaining marketing approval for the drug candidate; (ii) estimates regarding the timing of and the expected costs to develop and commercialize the drug candidate; (iii) estimates of future cash flows from potential product sales with respect to the drug candidate; and (iv) appropriate discount and tax rates. Standalone selling prices used to perform the initial allocation are not updated after contract inception. The Company does not include a financing component to its estimated transaction price at contract inception unless it estimates that certain performance obligations will not be satisfied within one year.

Upfront License Fees: If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from nonrefundable, upfront license fees based on the relative value prescribed to the license compared to the total value of the arrangement. The revenue is recognized when the license is transferred to the collaborator and the collaborator is able to use and benefit from the license. For licenses that are not distinct from other obligations identified in the arrangement, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time. If the combined performance obligation is satisfied over time, the Company applies an appropriate method of measuring progress for purposes of recognizing revenue from nonrefundable, upfront license fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition.

Development Milestone Payments: Depending on facts and circumstances, the Company may conclude it is appropriate to include the milestone in the estimated transaction price using the most likely amount method or it is appropriate to fully constrain the milestone. A milestone payment is included in the transaction price in the reporting period the Company concludes that it is probable that recording revenue in the period will not result in a significant reversal in amounts recognized in future periods. The Company may record revenues from certain milestones in a reporting period before the milestone is achieved if the Company concludes that achievement of the milestone is probable and that recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods. The Company records a corresponding contract asset when this conclusion is reached. Milestone payments that have not been included in the transaction price to date are fully constrained. These milestones remain fully constrained until the Company concludes that achievement of the milestone is probable and recognition of revenue related to the milestone will not result in a significant reversal in amounts recognized in future periods. The Company re-evaluates the probability of achievement of such development milestones and any related constraint each reporting period. The Company adjusts its estimate of the overall transaction price, including the amount of collaborative revenue that it has recorded, if necessary.

Sales-based Milestone and Royalty Payments: The Company’s collaborators may be required to pay the Company sales-based milestone payments or royalties on future sales of commercial products. The Company recognizes revenues related to sales-based milestone and royalty payments upon the later to occur of (i) achievement of the collaborator’s underlying sales or (ii) satisfaction of any performance obligation(s) related to these sales, in each case assuming the license to the Company’s intellectual property is deemed to be the predominant item to which the sales-based milestones and/or royalties relate.

Grant Income

Grant income is recognized as earned based on contract work performed.

Research and Development

Costs incurred in connection with research and development activities are expensed as incurred. Research and development expense consists of (i) employee-related expenses, including salaries, benefits, travel and stock-based compensation expense; (ii) external research and development expenses incurred under arrangements with third parties, such as contract research organizations and consultants; (iii) the cost of acquiring, developing and manufacturing clinical study materials; (iv) facilities and other expenses, which include direct and allocated expenses for rent and maintenance of facilities and laboratory and other supplies; and (v) costs associated with preclinical activities and regulatory operations.

The Company enters into consulting, research and other agreements with commercial firms, researchers, universities, and others for the provision of goods and services. Under such agreements, the Company may pay for services on a monthly, quarterly, project, or other basis. Such arrangements are generally cancellable upon reasonable notice and payment of costs incurred. Costs are considered incurred based on an evaluation of the progress to completion of specific tasks under each contract using information and data provided to the Company by its clinical sites and vendors. These costs consist of direct and indirect costs associated with specific projects, as well as fees paid to various entities that perform certain research on behalf of the Company.

Patents

Costs incurred in connection with the application for and issuances of patents are expensed as incurred.

Income Taxes

Income taxes are recorded in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (ASC) Topic 740, Income Taxes (ASC 740), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the condensed consolidated financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the condensed consolidated financial statement and tax bases of assets and liabilities and for loss and credit carryforwards using enacted tax rates anticipated to be in effect for the year in which the differences are expected to reverse. Valuation allowances are provided, if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that some or all of the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of September 30, 2018, and December 31, 2017, the Company does not have any significant uncertain tax positions. If incurred, the Company would classify interest and penalties on uncertain tax positions as income tax expense.

Net Income (Loss) per Share Attributable to Common Stockholders

The Company’s basic net income (loss) per share attributable to common stockholders is calculated by dividing the net income (loss) attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period. The diluted net income (loss) per share attributable to common stockholders is computed by adjusting the weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury stock method.

Stock-Based Compensation

The Company accounts for its stock-based compensation awards in accordance with FASB ASC Topic 718, Compensation – Stock Compensation (ASC 718), which requires that all stock-based payments to employees, including grants of employee stock options and restricted stock, be recognized in the condensed consolidated statements of operations and comprehensive income (loss) based on their fair values. All the Company’s stock-based awards are subject only to service-based vesting conditions. The Company estimates the fair value of its stock-based option awards using the Black-Scholes option pricing model, which requires the input of subjective assumptions, including (a) the expected stock price volatility; (b) the calculation of expected term of the award; (c) the risk-free interest rate; and (d) expected dividends. The fair value of restricted stock awards is determined based on the Company’s estimated common stock value.

Due to the lack of a public market for the trading of the Company’s common stock and a lack of company-specific historical and implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. The computation of expected volatility is based on the historical volatility of a representative group of companies with similar characteristics to the Company, including stage of product development and life science industry focus. The Company believes the group selected has sufficient similar economic and industry characteristics and includes companies that are most representative of the Company.

The Company uses the simplified method as prescribed by the SEC Staff Accounting Bulletin No. 107, Share-Based Payment, to calculate the expected term, as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term for options granted to employees and utilizes the contractual term for options granted to non-employees. The expected term is applied to the stock option grant group as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its employee population. The risk-free interest rate is based on a treasury instrument whose term is consistent with the expected life of the stock options.

Compensation expense related to awards to employees is calculated on a straight-line basis by recognizing the grant date fair value over the associated service period of the award which is generally the vesting term.

Fair Value of Financial Instruments

The Company’s financial instruments consist of cash equivalents, accounts payable and accrued expenses. The Company values cash equivalents using quoted market prices. The fair value of accounts payable and accrued expenses approximates its carrying value because of its short-term nature.

The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurements and Disclosures (ASC 820), establishes a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available.

Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below:

•

Level 1 – Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date

•

Level 2 – Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly

•

Level 3 – Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable

To the extent that a valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. There were no transfers within the fair value hierarchy during the nine months ended September 30, 2018. The assets of the Company measured at fair value on a recurring basis as of September 30, 2018, and December 31, 2017, are summarized below:

	Fair Value Measurements Using
	Level 1		Level 2		Level 3		Total
September 30, 2018
Assets:
Cash and cash equivalents	$	68,807,267	$	—	$	—	$	68,807,267
Total assets	$	68,807,267	$	—	$	—	$	68,807,267
December 31, 2017
Assets:
Cash and cash equivalents	$	20,264,109	$	—	$	—	$	20,264,109
Total assets	$	20,264,109	$	—	$	—	$	20,264,109

Concentrations of Credit Risk and Off-Balance Sheet Risk

Cash and cash equivalents are the only financial instruments that potentially subject the Company to concentrations of credit risk. At September 30, 2018, and December 31, 2017, all the Company’s cash was deposited in accounts at two principal financial institutions. The Company maintains its cash and cash equivalents with high-quality, accredited financial institutions and, accordingly, such funds are subject to minimal credit risk. The Company has no significant off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts or other hedging arrangements.

Comprehensive Income (Loss)

Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources, if any. Comprehensive income (loss) equaled net income (loss) for all periods presented.

Furniture and Equipment

Furniture and equipment is stated at cost, less accumulated depreciation. Furniture and equipment is depreciated using the straight-line method over the estimated useful lives of the assets, generally three to seven years. Such costs are periodically reviewed for recoverability when impairment indicators are present. Such indicators include, among other factors, operating losses, unused capacity, market value declines, and technological obsolescence. Recorded values of asset groups of furniture and equipment that are not expected to be recovered through undiscounted future net cash flows are written down to current fair value, which generally is determined from estimated discounted future net cash flows (assets held for use) or net realizable value (assets held for sale).

Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes the impact of recently issued standards that are not yet effective will not have a material impact on its condensed consolidated financial position or results of operations upon adoption.

In May 2014, the FASB issued amended guidance for revenue recognition, Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606).” This ASU outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers. The core principle of the guidance is that an entity should recognize revenue for the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. Additionally, the ASU requires improved disclosure to help users of financial statements better understand the nature, amount, timing and uncertainty of revenue that is recognized. The Company adopted the new guidance on January 1, 2018, as it relates to the Agreement discussed in Footnote 12.

In February 2016, the FASB issued ASU 2016-02, “Leases.” This ASU will require lessees to recognize almost all leases on the balance sheet as a right-of-use asset and a lease liability. For statement of operations purposes, the FASB retained a dual model, requiring leases to be classified as finance leases or operating leases. This update is effective for interim and annual periods beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the complete population of leases assessed under this ASU and evaluating the effect that adoption of this new standard will have on its accounting and disclosures. The adoption of this ASU will likely have a material impact on the condensed consolidated balance sheet.

In March 2016, the FASB issued ASU 2016-09, “Improvements to Employee Share-Based Payment Accounting.” This ASU is intended to simplify accounting for share-based payments and requires that excess tax benefits for share-based payments be recorded as a reduction of income tax expense and reflected within operating cash flows rather than being recorded within equity and reflected within financing cash flows. The ASU also provides an option for companies to recognize forfeitures as they occur rather than estimating the number of awards expected to be forfeited. The Company adopted this ASU on January 1, 2017 and has applied the new guidance related to excess tax benefits on a prospective basis. The Company also elected to account for forfeitures of share-based payments as they occur. The adoption of this ASU was not material to the condensed consolidated financial statements.

In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230).” The objective of this ASU is to provide additional guidance and reduce diversity in practice when classifying certain transactions within the statement of cash flows. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash.” This ASU requires that the statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. These ASUs are effective for financial statements issued for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company adopted these ASUs as of January 1, 2018. The adoption of these ASUs did not have a material impact on the Company’s condensed consolidated financial statements.

In May 2017, the FASB issued ASU 2017-09, “Stock Compensation - Scope of Modification Accounting.” This ASU provides clarification around which changes to the terms or conditions of a share-based payment award require the application of modification accounting under ASC 718. The Company adopted this ASU as of January 1, 2018. The adoption of this ASU did not have a material impact on the Company’s condensed consolidated financial statements.

In June 2018, the FASB issued ASU 2018-07, “Improvements to Nonemployee Share-Based Payment Accounting.” This ASU improves financial reporting for share-based payments issued to nonemployees under ASC 718 by expanding the scope of the employee share-based payments guidance to include share-based payments issued to nonemployees. The amendments in this ASU are effective for public companies for fiscal years beginning after December 31, 2018, including interim periods within that fiscal year. The Company has not yet adopted this ASU and is currently evaluating the effect that adoption of this new standard will have on its condensed consolidated financial statements.

Accounts Payable and Accrued Expenses

9 Months Ended

Sep. 30, 2018

Payables And Accruals [Abstract]

Accounts Payable and Accrued Expenses

3. Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses are as follows:

	September 30,		December 31,
	2018		2017
Accounts payable	$	717,000	$	1,276,537
Professional fees		499,835		277,217
Accrued bonus		1,077,901		833,650
Accrued vacation		228,048		69,549
Accrued project costs		1,032,787		1,069,852
Other		89,114		65,359
Total accounts payable and accrued expenses	$	3,644,685	$	3,592,164

Notes Payable to Investors	9 Months Ended
Notes Payable to Investors	Sep. 30, 2018
Debt Disclosure [Abstract]
Notes Payable to Investors	4. Notes Payable to Investors In 2016, Aerpio entered into a senior secured convertible note financing (the “Convertible Notes” or the “Convertible Note Financing”) totaling approximately $9,000,000. The Convertible Notes accrued interest at 8% per annum, compounded annually. The Convertible Notes were subject to mandatory prepayment upon the occurrence of certain events, such as a liquidation, dissolution or sale of Aerpio. In addition, and prior to maturity, the Convertible Notes were automatically convertible into shares of Aerpio capital stock upon the occurrence of a sale of Aerpio’s capital stock in a single transaction resulting in gross proceeds to Aerpio of $30,000,000 (hereinafter referred to as an “Investor Sale”). The type and class of Aerpio capital stock issued to the holder of each Convertible Note upon conversion would have been identical to the type and class of Aerpio capital stock issued in the Investor Sale. The holder of each Convertible Note was entitled to a number of shares of Aerpio capital determined by dividing (i) the outstanding principal amount of the Convertible Note plus any unpaid accrued interest by (ii) an amount equal to the price per share of Aerpio capital stock paid by the purchasers of such shares in connection with the Investor Sale. The Convertible Notes were secured by a first priority perfected security interest in all of the Aerpio’s assets. In October 2016 and February 2017, Aerpio executed additional senior secured Convertible Note financings (the “Additional Convertible Notes” or the “Additional Convertible Note Financings”) totaling approximately $3,500,000 and $300,000, respectively, with certain investors of Aerpio. The terms of the Additional Convertible Notes were identical to the Convertible Notes and were treated as extensions of the original Convertible Note Financing. The Company incurred $125,935 of costs associated with these transactions, which were amortized to the maturity date of March 31, 2017. In connection with the Additional Convertible Note Financings, the Convertible Notes were amended and their respective maturity dates were extended from October 31, 2016 to March 31, 2017. The amendments were accounted for as a modification for accounting purposes. In connection with the Merger (Note 1) the Convertible Notes, Additional Convertible Notes and accrued interest were converted into the Company’s common stock.

Common Stock	9 Months Ended
Common Stock	Sep. 30, 2018
Equity [Abstract]
Common Stock	5. Common Stock As of September 30, 2018 and December 31, 2017, the Company had 300,000,000 shares of authorized common stock with par value of $0.0001 per share. The common stock has the following characteristics. Voting The holders of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings. Dividends The holders of common stock are entitled to receive dividends, if and when declared by the Board of Directors. Since the Company’s inception, no dividends have been declared or paid to the holders of common stock. Liquidation In the event of any voluntary or involuntary liquidation, dissolution, or winding-up of the Company, the holders of common stock are entitled to share ratably in the Company’s assets. Warrants to Purchase Common Stock At September 30, 2018, and December 31, 2017, the Company had warrants outstanding for the purchase of 317,562 shares of the Company’s common stock at an exercise price of $5.00 per share. The warrants have a three-year term and expire on March 15, 2020. The warrants were issued in connection with the 2017 Offering. At the expiration date of the warrant, if the fair value of the Company’s common stock exceeds the exercise price, the warrant will be automatically exercised and the exercise price will be fulfilled through the net share settlement provisions. The number of shares and the exercise price shall be adjusted for standard ant-dilution events such as stock splits, combinations, reorganizations, or issue shares as part of a stock dividend. Upon a change of control, the warrant holder will have the right to receive securities, cash or other properties it would have been entitled to receive had the warrant been exercised. The warrants are equity classified instruments and do not contain contingent exercise provisions, or other features, that would preclude the Company from concluding that the warrants are indexed solely to the Company’s common stock.

Preferred Stock	9 Months Ended
Preferred Stock	Sep. 30, 2018
Equity [Abstract]
Preferred Stock	6. Preferred Stock As of both September 30, 2018 and December 31, 2017 the Company had 10,000,000 shares of preferred stock, par value $0.0001 per share, in authorized capital. No preferred stock was issued and outstanding at September 30, 2018 and December 31, 2017.

Stock-Based Compensation

9 Months Ended

Sep. 30, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

7. Stock-Based Compensation

Pursuant to the Merger (Note 1), the Company assumed the Aerpio Therapeutics, Inc. 2011 Equity Incentive Plan (the “2011 Plan”). Options covering an aggregate of 821,914 and 898,962 shares of the Company’s common stock at September 30, 2018, and December 31, 2017, respectively, are still governed by the 2011 Plan except that all references in the 2011 Plan to Aerpio, will now be the Company.

In March 2017, the Company’s Board of Directors adopted, and the stockholders approved, the 2017 Stock Option and Incentive Plan (the “2017 Plan”), that became effective in April 2017. The 2017 Plan provides for the issuance of incentive awards up to 4,600,000 shares of common stock to officers, employees, consultants and directors, less the number of shares subject to issued and outstanding awards under the 2011 Plan that were assumed in the Merger. The 2017 Plan also provides that the number of shares reserved for issuance thereunder will be increased annually on the first day of each year beginning in 2018 by four percent (4%) of the shares of our common stock outstanding on the last day of the immediately preceding year or such smaller increase as determined by our Board of Directors. In April 2018, the Company’s Board of Directors approved a 4% increase adding 1,082,802 shares to the 2017 Plan. As of September 30, 2018, and December 31, 2017, 2,615,062 and 1,179,410 stock awards were outstanding under the 2017 Plan and the 2011 Plan, respectively. This excludes 733,570 inducement stock awards issued outside of the 2017 Plan and the 2011 Plan outstanding at September 30, 2018, and December 31, 2017.

Stock Options

The options granted generally vest over 48 months. Under the 2017 Plan, options vest in installments of 25% at the one-year anniversary and thereafter in 36 equal monthly installments beginning on the 1^st of the month after the one-year anniversary date, subject to the employee’s continuous service with the Company. The options generally expire ten years after the date of grant. The fair value of the options at the date of grant is recognized as an expense over the requisite service period. 97,500 and 1,612,700 option awards were granted in the three and nine months ended September 30, 2018, respectively, and no option awards were granted in the three and nine months ended September 30, 2017. As of September 30, 2018, and December 31, 2017, 2,962,062 and 3,391,960 shares are reserved for issuance under the 2017 Plan, respectively.

The following table summarizes the stock option activity during the nine months ended September 30, 2018:

	Stock Option Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value
Outstanding, January 1, 2018		1,912,980		$	3.72		8.24	$	2,738,704
Granted		1,612,700			3.64
Exercised		(52,099	)		1.47
Expired/cancelled		(124,949	)		3.23
Outstanding, September 30, 2018		3,348,632		$	3.73		8.47	$	1,129,828
Expected to vest, September 30, 2018		2,436,229		$	4.27	9.41		$	61,555
Options exercisable, September 30, 2018		912,403		$	2.28		5.96	$	1,068,273

Aggregate intrinsic value represents the estimated fair value of the Company’s common stock at September 30, 2018, in excess of the weighted average exercise price multiplied by the number of options outstanding or exercisable.

Compensation expense for stock options was $759,978 and $53,814 for the three months ended September 30, 2018 and 2017, respectively and $2,314,201 and $173,888 for the nine months ended September 30, 2018 and 2017, respectively. As of September 30, 2018, there was $4,568,480 of unrecognized compensation cost related to stock options, which is expected to be recognized over a weighted average period of 2.63 years.

Restricted Stock

Shares of restricted stock generally have similar vesting terms as stock options. A summary of the Company’s restricted stock activity and related information during the nine months ended September 30, 2018 is as follows:

	Restricted Stock Shares			Weighted Average Grant Date Fair Value
Nonvested, January 1, 2018		91,576		$	2.12
Granted		60,000			4.75
Vested		(142,205	)		3.23
Forfeited		(2,333	)		2.25
Nonvested, September 30, 2018		7,038		$	2.21

The Company recognized compensation expense for restricted stock of $46,433 and $73,545 for the three months ended September 30, 2018 and 2017, respectively, and $449,689 and $220,380 for the nine months ended September 30, 2018 and 2017, respectively.

Compensation Expense Summary

The Company recognized the following compensation cost related to employee and non-employee stock-based compensation activity:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Research and development	$	139,492	$	88,443	$	313,505	$	276,778
General and administrative		666,919		38,916		2,450,385		117,490
Total	$	806,411	$	127,359	$	2,763,890	$	394,268

The Company uses the Black-Scholes option pricing model to determine the estimated fair value for stock-based awards. Option pricing and models require the input of various subjective assumptions, including the option’s expected life, expected dividend yield, price volatility and risk-free interest rate of the underlying stock. Accordingly, the weighted-average fair value of the options granted during the three and nine months ended September 30, 2018 was $2.13 and $2.24 per share, respectively. The calculation was based on the following assumptions.

	Three Months Ended	Nine Months Ended
	September 30, 2018	September 30, 2018
Expected term (years)	6.00	6.07
Risk-free interest rate	2.83%	2.85%
Expected volatility	65.12%	66.04%
Expected dividend yield	0.00%	0.00%

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes The Company did not record a current or deferred income tax expense or benefit for the nine months ended September 30, 2018 and 2017 due to the Company’s net losses and increases in its deferred tax asset valuation allowance. The impacts of The Tax Cuts and Jobs Act (the “2017 Tax Act”) disclosed in the December 31, 2017 Form 10-K were provisional in nature and there have been no adjustments the provisional amounts in the nine months ended September 30, 2018. We will continue to evaluate the provisional amounts in light of the requirements of the 2017 Tax Act until our 2017 Federal Income Tax Return is filed with the Internal Revenue Service Agency.

Net Income (Loss) Per Share Attributable to Common Stockholders

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

Net Income (Loss) Per Share Attributable to Common Stockholders

9. Net Income (Loss) per Share Attributable to Common Stockholders

The following is a reconciliation of the numerator and denominator of the basic and diluted net income (loss) per share (“EPS”) computations:

	Three Months Ended September 30,					Nine Months Ended September 30,
	2018		2017			2018			2017
Numerator:
Net and comprehensive income (loss)	$	11,537,478	$	(4,649,567	)	$	(1,878,046	)	$	(15,165,577	)
Adjustment of redeemable convertible preferred stock to redemption value		—		—			—			(943,297	)
Net income (loss) attributable to common stockholders	$	11,537,478	$	(4,649,567	)	$	(1,878,046	)	$	(16,108,874	)
Denominator:
Denominator for basic EPS - weighted-average common shares		40,527,722		26,926,673			31,687,434			19,889,984
Dilutive effect of options to purchase common shares		426,860		-			-			-
Dilutive effect of unvested restricted stock		7,038		-			-			-
Denominator for diluted EPS - adjusted weighted-average common shares		40,961,620		26,926,673			31,687,434			19,889,984

Basic and diluted EPS	$	0.28	$	(0.17	)	$	(0.06	)	$	(0.81	)

The diluted EPS calculation for the three months ended September 30, 2018 excludes 2.4 million options to purchase common stock that was outstanding but unvested and the effect of weighted average common stock share equivalents of 0.1 million for options to purchase common stock and 0.3 million for warrants to purchase common stock as their effect is anti-dilutive. Holders of non-vested stock-based compensation awards do not have voting rights.

The following weighted average common stock equivalents were excluded from the calculation of basic and diluted net loss per share attributable to common stockholders for the nine-month periods presented:

	Nine Months Ended September 30,
	2018		2017
Options to purchase common stock		3,348,632		898,962
Unvested restricted stock		7,038		129,835
Warrants to purchase common stock		317,562		317,562

Commitments and Contingencies

9 Months Ended

Sep. 30, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

10. Commitments and Contingencies

The Company is a party to a lease covering 7,580 square feet of space in Cincinnati, Ohio. The Company signed a fourth lease amendment in March 2018, extending the lease through July 2021. The lease agreement contains free rent and escalating rent payments. Rent expense is recorded on the straight-line basis over the initial term with the differences between rent expense and rent payments recorded as deferred rent. In November 2017, the Company renewed a lease covering 687 square feet of space in Dexter, MI that expires in October 2019. Total rent expense for all operating leases was $116,640 and $155,513 for the nine months ended September 30, 2018 and 2017, respectively. As of September 30, 2018, future payments related to operating leases activities are presented in the table below.

2018

2019

2020 and

Thereafter

Total

Operating leases

31,653

125,660

187,466

344,779

The Company contracts with various organizations to conduct research and development activities, including clinical trial organizations to manage clinical trial activities. The scope of the services under these research and development contracts can be modified and the contracts cancelled by the Company upon written notice. In the event of a cancellation, the Company would be liable for the cost and expenses incurred to date as well as any close out costs of the service arrangement.

Employee Stock Purchase Plan	9 Months Ended
Employee Stock Purchase Plan	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Employee Stock Purchase Plan	11. Employee Stock Purchase Plan In March 2017, the Board of Directors adopted and the stockholders approved the Employee Stock Purchase Plan that became effective in April 2017. On June 20, 2018, the Company’s shareholders approved the Amended and Restated 2017 Employee Stock Purchase Plan ("ESPP") at the Annual Meeting of Shareholders. Pursuant to the terms of the ESPP, the Company will reserve for issuance 300,000 shares of the Company's common stock in the aggregate, plus, on January 1, 2019 and each January 1 thereafter through January 1, 2028, the number of shares of the Company's common stock reserved and available for issuance under the ESPP will be cumulatively increased by the least of (i) one percent of the number of shares of the Company’s common stock issued and outstanding on the immediately preceding December 31; (ii) 350,000 shares; or (iii) such lesser number of shares of the Company’s common stock as determined by the Board of Directors, in each case subject to adjustment in accordance with the terms of the ESPP. No shares under the ESPP are outstanding at September 30, 2018 and December 31, 2017.

License Agreement	9 Months Ended
License Agreement	Sep. 30, 2018
Revenue From Contract With Customer [Abstract]
License Agreement	12. License Agreement On June 24, 2018, the Company entered into a License Agreement (the “Agreement”) with a wholly-owned subsidiary of Gossamer Bio, Inc., GB004, Inc. (collectively “Gossamer”), under which the Company granted Gossamer an exclusive, sublicensable license to develop and commercialize AKB-4924 and other structurally related products worldwide, with initial development expected in the indications of induction and maintenance in ulcerative colitis and Crohn’s Disease (collectively “initial indications”). Gossamer is responsible for the development and commercialization of the licensed products, and a joint development committee has been formed to oversee the development and manufacturing activities related to the licensed products. Under the terms of the Agreement, Gossamer is obligated to use its commercially reasonable efforts to develop and commercialize licensed products in the United States, two major European countries and Japan for at least one of the initial indications. The Agreement includes an exclusivity provision that prohibits the Company from developing, manufacturing or commercializing, and prohibits Gossamer from clinically developing or commercializing certain HIF stabilizing compounds other than as permitted in the Agreement. Pursuant to the terms of the Agreement, Gossamer made an upfront payment to the Company of $20.0 million on June 28, 2018. The Company is also eligible to receive development, commercial and sales milestone payments, with such payments contingent on the achievement of specified milestones with respect to the first licensed product for each of the first two initial indications. The Company is also eligible to receive tiered royalties on sales of licensed products at percentages ranging from a high-single-digit to mid-teens, subject to certain customary reductions. In addition, under certain circumstances, in lieu of receiving the foregoing milestone payments and royalties, the Company may elect to receive a specified percentage of payments received by Gossamer and its stockholders (with some exclusions) in connection with Gossamer’s grant of a sublicense or other rights to the licensed products or if Gossamer undergoes a change of control and the value of the transaction exceeds a certain value (provided that Gossamer can prevent the Company from exercising this option if the parent company of Gossamer is the entity undergoing the change of control). Conversely, the Company could be required to accept such a specified percentage of those payments if Gossamer agrees to pay the Company a certain minimum upon Gossamer and its stockholders being paid. Such amount may be reduced if the subject transaction includes pharmaceutical candidates or products or other named asset categories in addition to the licensed products. The Agreement expires on a licensed-product-by-licensed-product and country-by-country basis on the later of fifteen years from the date of first commercial sale or when there is no longer a valid patent claim covering such licensed product in such country. Either party may terminate the Agreement for an uncured material breach by the other party or upon the bankruptcy or insolvency of the other party. Gossamer may terminate the Agreement in the event Gossamer determines there is a potential safety or efficacy issue with the licensed products. The Company may terminate the Agreement if Gossamer institutes certain actions related to the licensed patents. Under certain termination circumstances, the Company would have worldwide rights to the terminated program. As of September 30, 2018 all development milestones, sales-based milestones and royalty payments within the Agreement are constrained to the point where no transaction price has been allocated to the future milestones or royalty payments. Consequently, at the date the Agreement was signed, the transaction price was solely attributable to the upfront payment which was recognized ratably over a ninety-day transition period in accordance with Topic 606 and the Company’s policy. The aforementioned transition period commenced on June 25, 2018 and $18.7 million and $20.0 million of license revenue was recorded within the condensed consolidated statement of operations and comprehensive income (loss) for the three and nine months ended September 30, 2018, respectively.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Basis of Presentation

Reclassification

Segment Information

Use of Estimates

Cash and Cash Equivalents

Revenue Recognition

Grant Income

Grant income is recognized as earned based on contract work performed.

Research and Development

Patents

Costs incurred in connection with the application for and issuances of patents are expensed as incurred.

Income Taxes

Net Income (Loss) per Share Attributable to Common Stockholders

Stock-Based Compensation

Fair Value of Financial Instruments

•

Level 1 – Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date

•

Level 2 – Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly

•

Level 3 – Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable

	Fair Value Measurements Using
	Level 1		Level 2		Level 3		Total
September 30, 2018
Assets:
Cash and cash equivalents	$	68,807,267	$	—	$	—	$	68,807,267
Total assets	$	68,807,267	$	—	$	—	$	68,807,267
December 31, 2017
Assets:
Cash and cash equivalents	$	20,264,109	$	—	$	—	$	20,264,109
Total assets	$	20,264,109	$	—	$	—	$	20,264,109

Concentrations of Credit Risk and Off-Balance Sheet Risk

Comprehensive Income (Loss)

Furniture and Equipment

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2018

Accounting Policies [Abstract]

Schedule of Assets Measured on Recurring Basis

The assets of the Company measured at fair value on a recurring basis as of September 30, 2018, and December 31, 2017, are summarized below:

	Fair Value Measurements Using
	Level 1		Level 2		Level 3		Total
September 30, 2018
Assets:
Cash and cash equivalents	$	68,807,267	$	—	$	—	$	68,807,267
Total assets	$	68,807,267	$	—	$	—	$	68,807,267
December 31, 2017
Assets:
Cash and cash equivalents	$	20,264,109	$	—	$	—	$	20,264,109
Total assets	$	20,264,109	$	—	$	—	$	20,264,109

Accounts Payable and Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2018

Payables And Accruals [Abstract]

Schedule of Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses are as follows:

	September 30,		December 31,
	2018		2017
Accounts payable	$	717,000	$	1,276,537
Professional fees		499,835		277,217
Accrued bonus		1,077,901		833,650
Accrued vacation		228,048		69,549
Accrued project costs		1,032,787		1,069,852
Other		89,114		65,359
Total accounts payable and accrued expenses	$	3,644,685	$	3,592,164

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes the stock option activity during the nine months ended September 30, 2018:

	Stock Option Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value
Outstanding, January 1, 2018		1,912,980		$	3.72		8.24	$	2,738,704
Granted		1,612,700			3.64
Exercised		(52,099	)		1.47
Expired/cancelled		(124,949	)		3.23
Outstanding, September 30, 2018		3,348,632		$	3.73		8.47	$	1,129,828
Expected to vest, September 30, 2018		2,436,229		$	4.27	9.41		$	61,555
Options exercisable, September 30, 2018		912,403		$	2.28		5.96	$	1,068,273

Summary of Restricted Stock Activity

A summary of the Company’s restricted stock activity and related information during the nine months ended September 30, 2018 is as follows:

	Restricted Stock Shares			Weighted Average Grant Date Fair Value
Nonvested, January 1, 2018		91,576		$	2.12
Granted		60,000			4.75
Vested		(142,205	)		3.23
Forfeited		(2,333	)		2.25
Nonvested, September 30, 2018		7,038		$	2.21

Summary of Recognized Compensation Cost Related to Employee and Non-employee Stock-Based Compensation Activity

The Company recognized the following compensation cost related to employee and non-employee stock-based compensation activity:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Research and development	$	139,492	$	88,443	$	313,505	$	276,778
General and administrative		666,919		38,916		2,450,385		117,490
Total	$	806,411	$	127,359	$	2,763,890	$	394,268

Stock Options Valuation Assumptions

The calculation was based on the following assumptions.

	Three Months Ended	Nine Months Ended
	September 30, 2018	September 30, 2018
Expected term (years)	6.00	6.07
Risk-free interest rate	2.83%	2.85%
Expected volatility	65.12%	66.04%
Expected dividend yield	0.00%	0.00%

Net Income (Loss) Per Share Attributable to Common Stockholders (Tables)

9 Months Ended

Sep. 30, 2018

Earnings Per Share [Abstract]

Schedule of Reconciliation of Numerator and Denominator of the Basic and Diluted Net Income (Loss) per Share

The following is a reconciliation of the numerator and denominator of the basic and diluted net income (loss) per share (“EPS”) computations:

	Three Months Ended September 30,					Nine Months Ended September 30,
	2018		2017			2018			2017
Numerator:
Net and comprehensive income (loss)	$	11,537,478	$	(4,649,567	)	$	(1,878,046	)	$	(15,165,577	)
Adjustment of redeemable convertible preferred stock to redemption value		—		—			—			(943,297	)
Net income (loss) attributable to common stockholders	$	11,537,478	$	(4,649,567	)	$	(1,878,046	)	$	(16,108,874	)
Denominator:
Denominator for basic EPS - weighted-average common shares		40,527,722		26,926,673			31,687,434			19,889,984
Dilutive effect of options to purchase common shares		426,860		-			-			-
Dilutive effect of unvested restricted stock		7,038		-			-			-
Denominator for diluted EPS - adjusted weighted-average common shares		40,961,620		26,926,673			31,687,434			19,889,984

Basic and diluted EPS	$	0.28	$	(0.17	)	$	(0.06	)	$	(0.81	)

Schedule of Weighted Average Common Stock Equivalents Excluded from Calculation of Basic and Diluted Net Loss per Share

	Nine Months Ended September 30,
	2018		2017
Options to purchase common stock		3,348,632		898,962
Unvested restricted stock		7,038		129,835
Warrants to purchase common stock		317,562		317,562

Commitments and Contingencies (Tables)

9 Months Ended

Sep. 30, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Payments Related to Operating Leases

As of September 30, 2018, future payments related to operating leases activities are presented in the table below

2018

2019

2020 and

Thereafter

Total

Operating leases

31,653

125,660

187,466

344,779

Nature of Organization and Operations - Additional Information (Detail)				9 Months Ended
	Jul. 02, 2018 USD ($) shares	Jun. 28, 2018 shares	Mar. 15, 2017 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2017 USD ($)	Dec. 31, 2017 $ / shares shares	Mar. 14, 2017 shares	Mar. 10, 2017 $ / shares shares	Mar. 03, 2017 $ / shares shares
Class Of Stock [Line Items]
Common stock, shares authorized				300,000,000		300,000,000		300,000,000	100,000,000
Common stock, par value \| $ / shares				$ 0.0001		$ 0.0001		$ 0.0001	$ 0.0001
Preferred stock, shares authorized				10,000,000		10,000,000		10,000,000	10,000,000
Preferred stock, par value \| $ / shares				$ 0.0001		$ 0.0001		$ 0.0001	$ 0.0001
Capital stock conversion basis ratio			2.3336572
Common stock, shares outstanding				40,588,004		27,070,038
Net proceeds of common stock issued to private placement \| $				$ 48,119,027
Warrants issued to purchase common stock, exercise price \| $ / shares				$ 5.00		$ 5.00
Payments of stock issuance cost \| $				$ 3,502,543	$ 3,084,385
Proceeds from sale of common stock \| $				$ 51,621,570	$ 40,247,775
2018 Public Offering [Member]
Class Of Stock [Line Items]
Common stock issued to private placement		11,688,000
Payments of stock issuance cost \| $	$ 3,500,000
Proceeds from sale of common stock \| $	$ 48,100,000
Underwriters’ Exercise of Option [Member]
Class Of Stock [Line Items]
Common stock issued to private placement	1,720,200
Minimum [Member]
Class Of Stock [Line Items]
Percentage of Interest owned in the combined enterprise			50.00%
Common Stock [Member]
Class Of Stock [Line Items]
Common stock issued to private placement				13,408,200
Net proceeds of common stock issued to private placement \| $				$ 1,341
Zeta Acquisition Corp. II [Member]
Class Of Stock [Line Items]
Number of shares surrendered for cancellation			4,000,000
Common stock, shares outstanding							5,000,000
Issuance of warrants term			3 years
Number of warrants issued to purchase common stock			317,562
Warrants issued to purchase common stock, exercise price \| $ / shares			$ 5.00
Zeta Acquisition Corp. II [Member] \| Common Stock [Member]
Class Of Stock [Line Items]
Common stock issued to private placement			8,049,555
Common stock issued to private placement, price per share \| $ / shares			$ 5.00
Net proceeds of common stock issued to private placement \| $			$ 37,200,000

Summary of Significant Accounting Policies - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2018 USD ($) Segment Institution	Dec. 31, 2017 USD ($) Institution
Summary Of Significant Accounting Policies [Line Items]
Number of operating segment \| Segment	1
Significant uncertain tax positions \| $	$ 0	$ 0
Number of principal financial institutions in cash deposit \| Institution	2	2
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Furniture and equipment estimated useful lives	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Furniture and equipment estimated useful lives	7 years

Summary of Significant Accounting Policies - Schedule of Assets Measured on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Assets:
Cash and cash equivalents	$ 68,807,267	$ 20,264,109
Total assets	68,807,267	20,264,109
Level 1 [Member]
Assets:
Cash and cash equivalents	68,807,267	20,264,109
Total assets	$ 68,807,267	$ 20,264,109

Accounts Payable and Accrued Expenses - Schedule of Accounts Payable and Accrued Expenses (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accounts payable	$ 717,000	$ 1,276,537
Professional fees	499,835	277,217
Accrued bonus	1,077,901	833,650
Accrued vacation	228,048	69,549
Accrued project costs	1,032,787	1,069,852
Other	89,114	65,359
Total accounts payable and accrued expenses	$ 3,644,685	$ 3,592,164

Notes Payable to Investors - Additional Information (Detail) - USD ($)	1 Months Ended		9 Months Ended
	Feb. 28, 2017	Oct. 31, 2016	Sep. 30, 2018	Dec. 31, 2016
Convertible Note Financing [Member]
Debt Instrument [Line Items]
Convertible notes payable				$ 9,000,000
Debt instrument, accrued interest rate			8.00%
Gross proceeds from sale of capital stock			$ 30,000,000
Additional Convertible Note Financings [Member]
Debt Instrument [Line Items]
Convertible notes payable	$ 300,000	$ 3,500,000
Maturity date	Mar. 31, 2017	Mar. 31, 2017
Debt issuance cost	$ 125,935	$ 125,935

Common Stock - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Mar. 10, 2017	Mar. 03, 2017
Equity [Abstract]
Common stock, shares authorized	300,000,000	300,000,000	300,000,000	100,000,000
Common stock, par value	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Dividends common stock declared or paid	$ 0
Warrants outstanding	317,562	317,562
Warrants exercise price per share	$ 5.00	$ 5.00
Warrants term	3 years	3 years
Warrants expiration date	Mar. 15, 2020	Mar. 15, 2020

Preferred Stock - Additional Information (Detail) - $ / shares	Sep. 30, 2018	Dec. 31, 2017	Mar. 10, 2017	Mar. 03, 2017
Temporary Equity Disclosure [Abstract]
Preferred stock, shares authorized	10,000,000	10,000,000	10,000,000	10,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Stock-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate number of common stock		3,348,632		3,348,632		1,912,980
Number of awards granted				1,612,700
Unrecognized compensation cost related to stock options		$ 4,568,480		$ 4,568,480
Weighted-average fair value of options granted		$ 2.13		$ 2.24
Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period				48 months
Compensation expense for stock options		$ 759,978	$ 53,814	$ 2,314,201	$ 173,888
Weighted average period expected to be recognized				2 years 7 months 17 days
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation expense for stock options		$ 46,433	$ 73,545	$ 449,689	$ 220,380
2011 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate number of common stock		821,914		821,914		898,962
2017 Stock Option and Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares available for issuance	1,082,802	4,600,000		4,600,000
Percentage applied to the outstanding shares as annual increase in number of shares authorized for issuance	4.00%			4.00%
2017 Stock Option and Incentive Plan [Member] \| Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares available for issuance		2,962,062		2,962,062		3,391,960
Term of options to be granted				10 years
Number of awards granted		97,500	0	1,612,700	0
2017 Stock Option and Incentive Plan [Member] \| Stock Option [Member] \| One-year Anniversary [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage				25.00%
Two Thousand Seventeen And Two Thousand Eleven Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate number of common stock		2,615,062		2,615,062		1,179,410
Two Thousand Seventeen And Two Thousand Eleven Plan \| Inducement Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate number of common stock		733,570		733,570		733,570

Stock-Based Compensation - Summary of Stock Option Activity (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding at beginning balance \| shares	1,912,980
Shares, Granted \| shares	1,612,700
Shares, Exercised \| shares	(52,099)
Shares, Expired/cancelled \| shares	(124,949)
Shares, Outstanding at ending balance \| shares	3,348,632	1,912,980
Shares, Expected to vest \| shares	2,436,229
Shares, Options exercisable \| shares	912,403
Weighted Average Exercise Price, Outstanding at beginning balance \| $ / shares	$ 3.72
Weighted Average Exercise Price, Granted \| $ / shares	3.64
Weighted Average Exercise Price, Exercised \| $ / shares	1.47
Weighted Average Exercise Price, Expired/cancelled \| $ / shares	3.23
Weighted Average Exercise Price, Outstanding at ending balance \| $ / shares	3.73	$ 3.72
Weighted Average Exercise Price, Expected to vest \| $ / shares	4.27
Weighted Average Exercise Price, Options exercisable \| $ / shares	$ 2.28
Weighted Average Remaining Contractual Term, Outstanding	8 years 5 months 19 days	8 years 2 months 26 days
Weighted Average Remaining Contractual Term, Expected to vest	9 years 4 months 28 days
Weighted Average Remaining Contractual Term, Options exercisable	5 years 11 months 15 days
Aggregate Intrinsic Value, Outstanding \| $	$ 1,129,828	$ 2,738,704
Aggregate Intrinsic Value, Expected to vest \| $	61,555
Aggregate Intrinsic Value, Options exercisable \| $	$ 1,068,273

Stock-Based Compensation - Summary of Restricted Stock Activity (Detail) - Restricted Stock [Member]	9 Months Ended
	Sep. 30, 2018 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Nonvested beginning balance \| shares	91,576
Shares, Granted \| shares	60,000
Shares, Vested \| shares	(142,205)
Shares, Forfeited \| shares	(2,333)
Shares, Nonvested ending balance \| shares	7,038
Weighted Average Grant Date Fair Value, Nonvested beginning balance \| $ / shares	$ 2.12
Weighted Average Grant Date Fair Value, Granted \| $ / shares	4.75
Weighted Average Grant Date Fair Value, Vested \| $ / shares	3.23
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	2.25
Weighted Average Grant Date Fair Value, Nonvested ending balance \| $ / shares	$ 2.21

Stock-Based Compensation - Summary of Recognized Compensation Cost Related to Employee and Non-employee Stock-Based Compensation Activity (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 806,411	$ 127,359	$ 2,763,890	$ 394,268
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	139,492	88,443	313,505	276,778
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 666,919	$ 38,916	$ 2,450,385	$ 117,490

Stock-Based Compensation - Stock Options Valuation Assumptions (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term (years)	6 years	6 years
Risk-free interest rate	2.83%	2.85%
Expected volatility	65.12%	66.04%
Expected dividend yield	0.00%	0.00%

Income Taxes - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Current income tax expense or benefit	$ 0	$ 0
Deferred income tax expense or benefit	0	$ 0
Tax Cuts and Jobs Act, Adjustments of provisional income tax expense benefit	$ 0

Net Income (Loss) Per Share Attributable to Common Stockholders - Schedule of Reconciliation of Numerator and Denominator of the Basic and Diluted Net Income (Loss) per Share (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Line Items]
Net and comprehensive income (loss)	$ 11,537,478	$ (4,649,567)	$ (1,878,046)	$ (15,165,577)
Adjustment of redeemable convertible preferred stock to redemption value				(943,297)
Net income (loss) attributable to common stockholders	$ 11,537,478	$ (4,649,567)	$ (1,878,046)	$ (16,108,874)
Denominator for basic EPS - weighted-average common shares	40,527,722	26,926,673	31,687,434	19,889,984
Denominator for diluted EPS - adjusted weighted-average common shares	40,961,620	26,926,673	31,687,434	19,889,984
Basic and diluted EPS	$ 0.28	$ (0.17)	$ (0.06)	$ (0.81)
Stock Option [Member]
Earnings Per Share [Line Items]
Dilutive effect of shares	426,860
Restricted Stock [Member]
Earnings Per Share [Line Items]
Dilutive effect of shares	7,038

Net Income (Loss) Per Share Attributable to Common Stockholders - Additional Information (Detail) - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Number of anti-dilutive securities excluded from computation of earnings per share	2,400,000
Weighted Average [Member] \| Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Number of anti-dilutive securities excluded from computation of earnings per share	100,000	3,348,632	898,962
Weighted Average [Member] \| Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Number of anti-dilutive securities excluded from computation of earnings per share	300,000	317,562	317,562

Net Income (Loss) Per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Net Loss per Share (Detail) - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total amount of anti-dilutive securities excluded from computation of earnings per share	2,400,000
Options to Purchase Common Stock [Member] \| Weighted Average [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total amount of anti-dilutive securities excluded from computation of earnings per share	100,000	3,348,632	898,962
Restricted Stock [Member] \| Weighted Average [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total amount of anti-dilutive securities excluded from computation of earnings per share		7,038	129,835
Warrants to Purchase Common Stock [Member] \| Weighted Average [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total amount of anti-dilutive securities excluded from computation of earnings per share	300,000	317,562	317,562

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	9 Months Ended
	Nov. 30, 2017 ft²	Sep. 30, 2018 USD ($) ft²	Sep. 30, 2017 USD ($)
Loss Contingencies [Line Items]
Total operating leases rent expense \| $		$ 116,640	$ 155,513
Cincinnati, Ohio [Member]
Loss Contingencies [Line Items]
Area of lease property		7,580
Lease expiration date		Jul. 31, 2021
Dexter, MI [Member]
Loss Contingencies [Line Items]
Area of lease property	687
Lease expiration date	Oct. 31, 2019

Commitments and Contingencies - Schedule of Future Payments Related to Operating Leases (Detail)	Sep. 30, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Operating leases, 2018	$ 31,653
Operating leases, 2019	125,660
Operating leases, 2020 and Thereafter	187,466
Operating leases, Total	$ 344,779

Employee Stock Purchase Plan - Additional Information (Detail) - shares	Jun. 20, 2018	Sep. 30, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding		3,348,632	1,912,980
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding		0	0
Common Stock [Member] \| Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares available for issuance	300,000
Maximum number of shares provided for issuance	350,000
Percentage of annual increase in number of shares reserved for issuance	1.00%

License Agreement - Additional Information (Detail) - USD ($)		3 Months Ended	9 Months Ended
	Jun. 28, 2018	Sep. 30, 2018	Sep. 30, 2018
License Agreement [Line Items]
Cash received from license agreement	$ 20,000,000
Revenue recognition period			90 days
License revenue		$ 18,821,953	$ 20,155,286
License [Member]
License Agreement [Line Items]
License revenue		$ 18,700,000	$ 20,000,000