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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2020	Aug. 10, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
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		42,068,004
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity File Number	001-38560
Entity Tax Identification Number	61-1547850
Entity Address, Address Line One	9987 Carver Road
Entity Address, City or Town	Cincinnati
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45242
City Area Code	513
Local Phone Number	985-1920
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance Sheets (Unaudited) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 44,864,284	$ 38,524,536
Prepaid research and development contracts	307,400	311,154
Other current assets	263,081	734,785
Total current assets	45,434,765	39,570,475
Furniture and equipment, net	146,216	164,187
Operating lease right-of-use assets, net	114,714	162,124
Deposits	20,000	40,000
Total assets	45,715,695	39,936,786
Current liabilities:
Accounts payable and accrued expenses	2,994,228	3,231,450
Current portion of operating lease liability	111,053	102,555
Total current liabilities	3,105,281	3,334,005
Operating lease liability, net of current portion	9,955	67,438
Total liabilities	3,115,236	3,401,443
Commitments and contingencies (Note 9)
Stockholders’ equity:
Common stock, $0.0001 par value per share; 300,000,000 shares authorized and 40,588,004 shares issued and outstanding at June 30, 2020 and December 31, 2019.	4,059	4,059
Additional paid-in capital	179,474,553	178,766,806
Accumulated deficit	(136,878,153)	(142,235,522)
Total stockholders’ equity	42,600,459	36,535,343
Total liabilities and stockholders’ equity	$ 45,715,695	$ 39,936,786

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
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	40,588,004
Common stock, shares outstanding	40,588,004	40,588,004

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (unaudited) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
License revenue	$ 15,000,000		$ 15,000,000
Revenue, Product and Service [Extensible List]	arpo:LicenseRevenueMember		arpo:LicenseRevenueMember
Operating expenses
Research and development	$ 3,548,572	$ 2,264,255	$ 5,377,614	$ 7,850,506
General and administrative	2,195,515	2,799,570	4,481,406	6,054,612
Restructuring expense		915,094		915,094
Total operating expenses	5,744,087	5,978,919	9,859,020	14,820,212
Income (loss) from operations	9,255,913	(5,978,919)	5,140,980	(14,820,212)
Grant income		4,924	79,900	20,272
Interest income	20,119	290,379	136,489	623,499
Total other income	20,119	295,303	216,389	643,771
Net and comprehensive income (loss)	$ 9,276,032	$ (5,683,616)	$ 5,357,369	$ (14,176,441)
Net and comprehensive income (loss) per share
Basic and diluted	$ 0.23	$ (0.14)	$ 0.13	$ (0.35)
Weighted average number of common shares used in computing net and comprehensive income (loss) per share
Basic	40,588,004	40,588,004	40,588,004	40,588,004
Diluted	40,905,288	40,588,004	40,747,960	40,588,004

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance at Dec. 31, 2018	$ 58,666,575	$ 4,059	$ 177,621,807		$ (118,959,291)
Balance (ASU 2018-07 [Member]) at Dec. 31, 2018				$ 5,717		$ (5,717)
Balance, Shares at Dec. 31, 2018		40,588,004
Stock-based compensation expense	621,685		621,685
Net and comprehensive income (loss)	(8,492,825)				(8,492,825)
Balance at Mar. 31, 2019	50,795,435	$ 4,059	178,249,209		(127,457,833)
Balance, Shares at Mar. 31, 2019		40,588,004
Balance at Dec. 31, 2018	58,666,575	$ 4,059	177,621,807		(118,959,291)
Balance (ASU 2018-07 [Member]) at Dec. 31, 2018				$ 5,717		$ (5,717)
Balance, Shares at Dec. 31, 2018		40,588,004
Net and comprehensive income (loss)	(14,176,441)
Balance at Jun. 30, 2019	45,716,480	$ 4,059	178,853,870		(133,141,449)
Balance, Shares at Jun. 30, 2019		40,588,004
Balance at Mar. 31, 2019	50,795,435	$ 4,059	178,249,209		(127,457,833)
Balance, Shares at Mar. 31, 2019		40,588,004
Stock-based compensation expense	604,661		604,661
Net and comprehensive income (loss)	(5,683,616)				(5,683,616)
Balance at Jun. 30, 2019	45,716,480	$ 4,059	178,853,870		(133,141,449)
Balance, Shares at Jun. 30, 2019		40,588,004
Balance at Dec. 31, 2019	36,535,343	$ 4,059	178,766,806		(142,235,522)
Balance, Shares at Dec. 31, 2019		40,588,004
Issuance of warrants	62,347		62,347
Stock-based compensation expense	327,467		327,467
Net and comprehensive income (loss)	(3,918,663)				(3,918,663)
Balance at Mar. 31, 2020	33,006,494	$ 4,059	179,156,620		(146,154,185)
Balance, Shares at Mar. 31, 2020		40,588,004
Balance at Dec. 31, 2019	36,535,343	$ 4,059	178,766,806		(142,235,522)
Balance, Shares at Dec. 31, 2019		40,588,004
Net and comprehensive income (loss)	5,357,369
Balance at Jun. 30, 2020	42,600,459	$ 4,059	179,474,553		(136,878,153)
Balance, Shares at Jun. 30, 2020		40,588,004
Balance at Mar. 31, 2020	33,006,494	$ 4,059	179,156,620		(146,154,185)
Balance, Shares at Mar. 31, 2020		40,588,004
Issuance of warrants	9,592		9,592
Stock-based compensation expense	308,341		308,341
Net and comprehensive income (loss)	9,276,032				9,276,032
Balance at Jun. 30, 2020	$ 42,600,459	$ 4,059	$ 179,474,553		$ (136,878,153)
Balance, Shares at Jun. 30, 2020		40,588,004

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

+ References + Details

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities:
Net and comprehensive income (loss)	$ 5,357,369	$ (14,176,441)
Adjustments to reconcile net and comprehensive income (loss) to net cash provided by (used in) operating activities:
Depreciation	30,169	33,503
Stock-based compensation	635,808	1,226,346
Consulting expense related to warrants	71,939
Changes in operating assets and liabilities:
Prepaid research and development contracts	3,754	386,344
Other current assets	491,704	351,376
Accounts payable and other current liabilities	(238,797)	(2,045,456)
Net cash provided by (used in) operating activities	6,351,946	(14,224,328)
Investing activities:
Purchase of furniture and equipment	(12,198)	(232,672)
Net cash used in investing activities	(12,198)	(232,672)
Net increase (decrease) in cash and cash equivalents	6,339,748	(14,457,000)
Cash and cash equivalents at beginning of year	38,524,536	62,614,010
Cash and cash equivalents, six months ended	$ 44,864,284	$ 48,157,010

Nature of Organization and Operations

6 Months Ended

Jun. 30, 2020

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 developing compounds that activate Tie2 to treat ocular diseases and diabetic complications, as well as other indications in which the Company believes that activation of Tie2 may have therapeutic potential, including acute respiratory distress syndrome (“ARDS”) associated with COVID-19 infections. The Company was incorporated as Zeta Acquisition Corp. II (“Zeta”) in the State of Delaware on November 16, 2007. Zeta was a “shell company” (as defined in Rule 12b-2 of the Securities Exchange Act of 1934, as amended).

The Company’s pipeline includes the following programs:

Glaucoma: Based on the preclinical proof of concept and the results of the Phase 1b trial showing a reduction in intraocular pressure (“IOP”) in patients with ocular hypertension (“OHT”) and open angle glaucoma (“OAG”), the Company initiated a Phase 2 clinical trial in June 2020 designed to evaluate the safety and efficacy of a topical formulation of razuprotafib (AKB-9778) in approximately 195 patients followed over a 28-day period. Patients enrolled in the trial will be administered a baseline of latanoprost ophthalmic solution 0.005%, and then randomized in a 1:1:1 fashion to receive adjunctive therapy consisting of placebo, 40 mg/ml razuprotafib once-daily, or 40 mg/ml razuprotafib twice-daily. The primary endpoint of the study is mean diurnal IOP at 28 days in the razuprotafib treated groups compared to the latanoprost monotherapy group. The Company expects to have results in the fourth quarter of 2020, subject to potential delays in subject enrollment and study completion, including due to delays arising from the ongoing COVID-19 pandemic.

Acute Respiratory Distress Syndrome (“ARDS”): Based on results in preclinical studies and observations in patients in the TIME-2 and TIME-2b trials, the Company believes that a vascular endothelial receptor, Tie2, may play a pivotal role in the defense against microvascular breach in ARDS. The Company hypothesizes that razuprotafib, the Company’s lead Tie2 activator, may have therapeutic potential for the treatment of COVID-19 associated ARDS. In May 2020, the Company was selected by Quantum Leap Healthcare Collaborative to participate in the I-SPY COVID-19 Trial (Investigation of Serial studies to Predict Your COVID Therapeutic Response with biomarker Integration and Adaptive Learning) to evaluate razuprotafib for the treatment of COVID-19 related ARDS in adult patients with critical COVID-19. The Company expects the trial to be initiated during the third quarter of 2020 with trial updates anticipated in the first half of 2021, subject to potential delays in subject enrollment and study completion, including due to delays arising from the ongoing COVID-19 pandemic.

Diabetic Kidney Disease: In two consecutive trials, TIME-2 and TIME-2b, subcutaneous razuprotafib (AKB-9778) showed reduction in Urine Albumin-Creatinine Ratio (“UACR”), a measure of progression of diabetic kidney disease. The Company believes that systemic treatment with razuprotafib could have the potential to change the treatment paradigm for diabetics in the future and potentially address a major societal problem by lowering the cost of care associated generally with diabetes.

ARP-1536: The humanized monoclonal antibody, ARP-1536, directed at the same target as subcutaneous razuprotafib (AKB-9778), is in preclinical development. The Company is evaluating development options for ARP-1536, including subcutaneous injection for the treatment of diabetic vascular complications, e.g., diabetic nephropathy and intravitreal injection as an adjunctive therapy for diabetic macular edema.

The Company is also developing a bispecific antibody that binds both VEGF and VE-PTP which is designed to inhibit VEGF activation and activate Tie2. The Company believes this bispecific antibody has the potential to be an improved treatment for wet aged-related macular degeneration (“AMD”) and diabetic macular edema via intravitreal injection.

In June 2018, the Company licensed AKB-4924 (now GB004), a selective stabilizer of hypoxia-inducible factor-1 alpha (“HIF-1 alpha”) to a wholly-owned subsidiary of Gossamer Bio, Inc., GB004, Inc. (collectively “Gossamer”), which is being developed for the treatment of inflammatory bowel disease (“IBD”). HIF-1 alpha is involved in mucosal wound healing and the reduction of inflammation in the gastrointestinal tract. Gossamer completed the Phase 1b clinical study in ulcerative colitis patients and reported results during the second quarter of 2020. Gossamer has reported that it is planning for the commencement of its Phase 2 program for GB004 in the first half of 2021, subject to potential delays in subject enrollment and study completion, including due to delays arising from the ongoing COVID-19 pandemic.

In May 2020, the Company received a one-time payment of $15.0 million pursuant to an amendment to its license agreement with Gossamer resulting in a reduction in future potential milestone payments and tiered royalty rates over the life of the Agreement. Gossamer is responsible for all remaining development and commercial activities for GB004.

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 has been primarily limited to license revenue from Gossamer described in Note 11. 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 pipeline products that are approved, and protection of proprietary technology. If the Company does not successfully commercialize any of its pipeline products or mitigate any of these other risks, it will be unable to generate revenue or achieve profitability.

Excluding the one-time payments from Gossamer, the Company incurred losses from operations and had negative cash flows from operating activities for the six months ended June 30, 2020 and 2019 (and since inception). The Company’s current operating plan indicates that it will continue to incur losses from operations and generate negative cash flows from operating activities given ongoing expenditures related to the completion of its ongoing clinical trials and the Company’s lack of product revenue generating activities. However, the Company believes it has the ability to control its current operating plan and that existing cash and cash equivalents of approximately $44.9 million at June 30, 2020 will be sufficient to allow the Company to fund its current operating plan through at least the fourth quarter of 2021.

There can be no assurance, however, that the current operating plan will be achieved in the time frame anticipated by the Company, or that its cash resources will fund the Company’s operating plan for the period anticipated by the Company or that additional funding will be available on terms acceptable to the Company, or at all. The Company will need to raise additional funds in order to further advance its clinical research programs, commence additional clinical trials, and operate its business and meet its obligations as they come due. The Company is pursuing financing alternatives, which include permanent equity financing, business development arrangements, and licensing arrangements. However, financing may not be available to the Company in the necessary time frame, in amounts that the Company requires, on terms that are acceptable to the Company, or at all. If the Company raises additional funds through collaboration, licensing or other similar arrangements, it may be necessary to relinquish valuable rights to its potential products or proprietary technologies or grant licenses on terms that are not favorable to the Company. If the Company is unable to raise the necessary funds when needed or reduce spending on currently planned activities, it may not be able to continue the development of its product candidates or the Company could be required to delay, scale back, or eliminate some or all of its development programs and other operations and will materially harm its business, financial position and results of operations.

COVID-19 has resulted, and will likely continue to result, in significant governmental measures being implemented to control the spread of the virus through quarantines, travel restrictions, heightened border security and other measures. While the Company cannot predict the scope and severity, these developments and measures could materially and adversely affect its business, including its planned Phase 2 clinical trials for the glaucoma and ARDS programs, results of operations and financial condition. In addition, in response to the continuing spread of COVID-19, the Company has kept its executive offices closed with its employees continuing their work outside of the office. The Company is closely monitoring the impact of COVID-19 on all aspects of its business and is taking steps to minimize the impact on its business. However, the extent to which COVID-19 ultimately impacts the Company’s business, results of operations or financial condition will depend on future developments, which remain highly uncertain and cannot be predicted with confidence, such as the duration of the pandemic, new information that may emerge concerning the severity of COVID-19 and the effectiveness of actions taken to contain the pandemic or treat its impact, among others. While states and jurisdictions have started to rollback stay-at-home and quarantine orders, it is difficult to predict what the lasting impact of the pandemic will be, and if the Company or any of the third parties with whom it engages were to experience additional shutdowns or other prolonged business disruptions, the Company’s ability to conduct its business in the manner and on the timelines presently planned could have a material adverse impact on the Company’s business, results of operation and financial condition.

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2020

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. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). 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 as of and for the year ended December 31, 2019, included in the Company’s Annual Report on Form 10-K filed with the SEC on March 16, 2020. 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.

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 that are 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: prepaid and accrued research and development expense, stock-based compensation expense, revenue recognition and income taxes.

The Company’s results can also be affected by economic conditions, global health concerns, such as COVID-19, and 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 and $100,000 invested in short-term certificates of deposits with original maturities of three months or less at the time of purchase. At June 30, 2020 and December 31, 2019, the Company’s cash equivalents are primarily in money market funds. The Company maintains 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.

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 (or one-time) 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 cash is received or 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, 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

Research and development costs 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, and (iv) costs associated with clinical, preclinical and regulatory activities.

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 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 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 June 30, 2020 and December 31, 2019, the Company does not have any uncertain tax positions. The Company recognizes interest and penalties related to uncertain tax positions, if any exist, in income tax expense.

Net and Comprehensive Income (Loss) per Share Attributable to Common Stockholders

The Company’s basic net and comprehensive income (loss) per share attributable to common stockholders is calculated by dividing the net and comprehensive income (loss) by the weighted average number of shares of common stock outstanding for the period. The diluted net and comprehensive 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 ASC Topic 718, Compensation – Stock Compensation (“ASC 718”). ASC 718 requires all stock-based payments to employees, including grants of employee stock options, to 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 awards using the Black-Scholes option pricing model, which requires the input of 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.

Due to the historical lack of public market for 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 and 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. 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 six months ended June 30, 2020 or 2019. The assets of the Company measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019, are summarized below:

	Fair Value Measurements Using
	Level 1		Level 2		Level 3		Total
June 30, 2020
Assets:
Cash and cash equivalents	$	44,864,284	$	—	$	—	$	44,864,284
Total assets	$	44,864,284	$	—	$	—	$	44,864,284
December 31, 2019
Assets:
Cash and cash equivalents	$	38,524,536	$	—	$	—	$	38,524,536
Total assets	$	38,524,536	$	—	$	—	$	38,524,536

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 June 30, 2020 and December 31, 2019, 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).

Leases

At the inception of an arrangement the Company determines whether the arrangement is or contains a lease based on the circumstances present. All leases with a term greater than one year are recognized on the condensed consolidated balance sheet as right-of-use assets, lease liabilities and, if applicable, long-term lease liabilities. The Company has elected not to recognize on the condensed consolidated balance sheet leases with terms of one-year or less if entered into. Lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes the appropriate incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received.

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 financial position or results of operations upon adoption.

In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”). ASU 2018-07 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 ASU 2018-07 are effective for public companies for fiscal years beginning after December 31, 2018, including interim periods within that fiscal year. The Company adopted ASU 2018-07 as of January 1, 2019 and recorded a one-time cumulative adjustment of $5,717 upon adoption.

No other new accounting pronouncement recently issued or newly effective had or is expected to have a material impact on the Company’s condensed consolidated financial statements.

Accounts Payable and Accrued Expenses

6 Months Ended

Jun. 30, 2020

Payables And Accruals [Abstract]

Accounts Payable and Accrued Expenses

3. Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses are as follows:

	June 30,		December 31,
	2020		2019
Accrued retention bonus	$	918,944	$	521,859
Accounts payable		622,658		439,785
Accrued project costs		389,854		382,131
Professional fees		355,602		346,999
Accrued bonus		318,591		689,830
Restructuring accrual (see Note 12)		278,846		793,913
Accrued vacation		79,820		43,470
Other		29,913		13,463
Total accounts payable and accrued expenses	$	2,994,228	$	3,231,450

Common Stock

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Common Stock

4. Common Stock

As of June 30, 2020 and December 31, 2019, 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 of the Company (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 June 30, 2020 and December 31, 2019, the Company had warrants outstanding for the purchase of 600,000 and 917,562 shares, respectively, of the Company’s common stock. In October 2019, the Company issued warrants for the purchase of 600,000 shares of the Company’s common stock at an exercise price of $0.486 per share in connection with the hiring of a strategic advisor consultant for a six-month period. These warrants vested in equal monthly installments over a six-month period beginning October 14, 2019 and expire on October 24, 2024. At the date of grant the fair value of these awards were determined using a Black-Scholes Merton pricing model. Included at December 31,2019, are warrants for the purchase of 317,562 shares of the Company’s common stock at an exercise price of $5.00 per share that were issued in connection with the 2017 Offering and have a three-year term. The 317,562 warrants expired on March 15, 2020, and none were exercised or settled as the fair value of the Company’s common stock was below the exercise price.

The number of shares and the exercise price shall be adjusted for standard anti-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

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Preferred Stock

5. Preferred Stock

As of June 30, 2020 and December 31, 2019, 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 June 30, 2020 and December 31, 2019.

Stock-Based Compensation

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

6. Stock-Based Compensation

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 March 2020, the Company’s Board of Directors approved a 4% increase adding 1,623,520 shares to the 2017 Plan, which was effective as of January 1, 2020.

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. In May 2019, the Company issued a special retention grant of options to purchase an aggregate of 2,419,050 shares of common stock which vest in installments of 50% at June 30, 2020 and 50% at June 30, 2021, 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. During the three months ended June 30, 2020 and 2019, option awards to purchase an aggregate of 260,720 and 2,801,600 shares of common stock were granted, respectively, and option awards to purchase an aggregate of 962,720 and 4,622,428 shares of common stock were granted in the six months ended June 30, 2020 and 2019, respectively.

As of June 30, 2020 and December 31, 2019, 3,570,705 and 1,983,093 shares were reserved for issuance under the 2017 Plan, respectively.

The following table summarizes the stock option activity during the six months ended June 30, 2020:

	Stock Option Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value
Outstanding, January 1, 2020		5,335,850		$	2.60		6.23	$	2,866
Granted		962,720			0.71
Exercised		—			—
Expired/cancelled		(1,452,470	)		4.01
Outstanding, June 30, 2020		4,846,100		$	1.80		7.39	$	1,014,874
Expected to vest, June 30, 2020		2,295,314		$	1.56		8.98	$	678,430
Options exercisable, June 30, 2020		2,550,786		$	2.02		5.97	$	336,444

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

As of June 30, 2020, there was $2,108,948 of unrecognized compensation cost related to stock options, which is expected to be recognized over a weighted average period of 1.98 years.

Compensation Expense Summary

The Company recognized the following compensation cost related to stock-based compensation activity for the periods presented:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Research and development	$	176,110	$	73,463	$	371,899	$	232,794
General and administrative		132,231		531,198		263,909		993,552
Total	$	308,341	$	604,661	$	635,808	$	1,226,346

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 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 six months ended June 30, 2020 was $0.76 and $0.43 per share, respectively. The calculation was based on the following assumptions.

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020	2019
Expected term (years)		5.50		5.82	5.92	5.77
Risk-free interest rate	0.38%		2.21%		0.53%	2.32%
Expected volatility	74.82%		65.97%		69.36%	65.83%
Expected dividend yield	0.00%		0.00%		0.00%	0.00%

Income Taxes

6 Months Ended

Jun. 30, 2020

Income Tax Disclosure [Abstract]

Income Taxes

7. Income Taxes

The Company did not record a current or deferred income tax expense or benefit for the three and six months ended June 30, 2020 and 2019, due to the Company’s net and comprehensive income (loss) and increases in its deferred tax asset valuation allowance.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Net and Comprehensive Income (Loss) Per Share Attributable to Common Stockholders

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Net and Comprehensive Income (Loss) Per Share Attributable to Common Stockholders

8. Net and Comprehensive Income (Loss) per Share Attributable to Common Stockholders

The following table sets forth the computation of the Company’s basic and diluted net and comprehensive income (loss) per share (“EPS”) attributable to common stockholders for the periods presented:

	Three Months Ended June 30,					Six Months Ended June 30,
	2020		2019			2020		2019
Numerator:
Net and comprehensive income (loss) per share	$	9,276,032	$	(5,683,616	)	$	5,357,369	$	(14,176,441	)
Denominator:
Weighted average common shares used in computing EPS
Basic		40,588,004		40,588,004			40,588,004		40,588,004
Diluted		40,905,288		40,588,004			40,747,960		40,588,004

Basic and diluted EPS	$	0.23	$	(0.14	)	$	0.13	$	(0.35	)

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 and comprehensive income (loss) per share for the periods presented because including them would have had an anti-dilutive effect:

	Six Months Ended June 30,
	2020		2019
Options to purchase common stock		4,846,100		6,771,807
Warrants to purchase common stock		600,000		317,562

Leases

6 Months Ended

Jun. 30, 2020

Leases [Abstract]

Leases

9. Leases

At June 30, 2020, the Company is a party to one property lease in Cincinnati, Ohio under an arrangement which provides the right to use the underlying asset and require lease payments for the lease term. During the fourth quarter of 2019, the Company terminated its leases in Lexington, Massachusetts and Dexter, Michigan; no penalties were incurred related to these terminations. The Cincinnati, Ohio lease agreement obligates the Company to pay real estate taxes, insurance and certain maintenance costs (hereinafter referred to as non-lease components). The Company’s lease arrangement contains a renewal provision of 5 years, exercisable at the Company's option. The Company’s lease agreement does not contain any material residual value guarantees or material restrictive covenants.

Operating lease assets and operating lease liabilities are recognized at commencement date based on the present value of lease payments over the lease term and include options to extend or terminate the lease when they are reasonably certain to be exercised. The present value of lease payments is determined primarily using the incremental borrowing rate based on the information available at lease commencement date. Lease agreements with lease and non-lease components are generally accounted for as a single lease component. The Company’s operating lease expense is recognized on a straight-line basis over the lease term and are recorded in general and administrative expenses on the condensed consolidated statements of operations and comprehensive income (loss).

The following table presents the lease cost and information related to the right-of-use assets and operating lease liabilities:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020			2019
Lease cost
Average rent expense	$	28,357	$	62,085	$	56,715		$	124,140

Other information
Cash paid for amounts included in the measurement of operating lease liabilities	$	29,145	$	62,154	$	58,290		$	124,308

The weighted average remaining lease term and discount rate at June 30, 2020
Weighted-average remaining lease term - operating leases						1.08
Weighted-average discount rate - operating leases						13.28	%

As of June 30, 2020, future payments related to operating leases activities are presented in the table below:

	2020		2021		2022 and Thereafter		Total Lease Payments
Operating leases	$	59,490	$	69,685	$	—	$	129,175
Less interest								(8,167	)
Present value of lease liabilities							$	121,008

Employee Stock Purchase Plan

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Employee Stock Purchase Plan

10. 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. In March 2020, the Company’s Board of Directors approved an increase of 350,000 shares to the ESPP, which increase was effective as of January 1, 2020. No shares under the ESPP are outstanding at June 30, 2020 and December 31, 2019.

License Agreement

6 Months Ended

Jun. 30, 2020

Revenue From Contract With Customer [Abstract]

License Agreement

11. License Agreement

On June 24, 2018, the Company entered into a license agreement (the “Gossamer License Agreement”) with 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”). Prior to the execution of the Gossamer License Agreement, AKB-4924 was a pipeline program for the Company that completed a Phase 1a clinical trial in healthy volunteers.

On May 12, 2020, the Company entered into Amendment No. 1 to the Gossamer License Agreement (“Amendment 1”). Pursuant to Amendment 1, Gossamer made a payment to the Company of $15.0 million on May 12, 2020. For the three and six months ended June 30, 2020, the Company recognized revenue of $15.0 million based on the terms of Amendment 1.

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 Gossamer License Agreement and as amended by Amendment 1 (the “Gossamer 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 Gossamer 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 Gossamer Agreement.

Under the terms of the Gossamer Agreement, the Company is eligible to receive up to $40.0 million in approval milestone payments related to indications in ulcerative colitis and Crohn’s disease, and up to $50.0 million in sales milestone payments. The Company is also eligible to receive the tiered royalties on sales of licensed products from percentages ranging from a low-single-digit to mid-single-digit, 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 20% 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, in which case each of the royalty rate percentages described above would automatically be increased by low single digits). Conversely, the Company could be required to accept such 20% 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 transaction includes pharmaceutical candidates or products or other named asset categories in addition to the licensed products.

The Gossamer 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 Gossamer Agreement for an uncured material breach by the other party or upon the bankruptcy or insolvency of the other party. Gossamer may terminate the Gossamer Agreement in the event Gossamer determines there is a potential safety or efficacy issue with the licensed products. The Company may terminate the Gossamer 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 June 30, 2020 and 2019, all development milestones, sales-based milestones and royalty payments within the Gossamer License Agreements are constrained to the point where no transaction price has been allocated to the future milestones or royalty payments.

Restructuring

6 Months Ended

Jun. 30, 2020

Restructuring And Related Activities [Abstract]

Restructuring

12. Restructuring

In April 2019, the Company executed a realignment plan to reduce operating costs and better align its workforce with the needs of its ongoing business and in October 2019, the Company’s Chief Executive Officer and Chief Financial Officer departed from their positions. As a result, the Company recorded employee severance expense of $0.9 million during the three and six months ended June 30, 2019 and an additional $1.0 million in the three months ended December 31, 2019. The severance liability as of December 31, 2019 was approximately $0.8 million and was included in accounts payable and accrued expenses in the condensed consolidated balance sheet.

Total cash payments against the severance liability was approximately $0.3 million and $0.6 million in the three and six months ended June 30, 2020, respectively. The remaining liability as of June 30, 2020, was approximately $0.3 million and is included in accounts payable and accrued expenses in the condensed consolidated balance sheet. These amounts are expected to be substantially paid in cash by October 31, 2020.

Subsequent Event

6 Months Ended

Jun. 30, 2020

Subsequent Events [Abstract]

Subsequent Event

13. Subsequent Event

In February 2018, the Company filed a shelf registration statement on Form S-3 with the SEC which was declared effective by the SEC on April 11, 2018 (the “Form S-3”). On February 21, 2018, and pursuant to the Form S-3, the Company entered into a Controlled Equity Offering Sales Agreement (the “Sales Agreement”) with Cantor Fitzgerald & Co. (“Cantor”), pursuant to which it may issue and sell, from time to time, shares of its common stock having an aggregate offering price of up to $75.0 million through Cantor as the sales agent. Cantor may sell the Company’s common stock by any method permitted by law deemed to be an “at the market offering” as defined in Rule 415(a)(4) of the Securities Act, including sales made directly on or through the Nasdaq Capital Market or any other existing trade market for the Company’s common stock, in negotiated transactions at market prices prevailing at the time of sale or at prices related to prevailing market prices, or any other method permitted by law. On August 5, 2020, 1,480,000 shares of the Company’s common stock were sold under the Sales Agreement, pursuant to the Form S-3, the related prospectus, and the prospectus supplement. The net proceeds received from this transaction were $2.3 million, after deducting expenses of approximately $186,000 (including sales agent compensation of approximately $75,000) related to the sale of the Company’s common stock.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2020

Accounting Policies [Abstract]

Basis of Presentation

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 and Comprehensive 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
June 30, 2020
Assets:
Cash and cash equivalents	$	44,864,284	$	—	$	—	$	44,864,284
Total assets	$	44,864,284	$	—	$	—	$	44,864,284
December 31, 2019
Assets:
Cash and cash equivalents	$	38,524,536	$	—	$	—	$	38,524,536
Total assets	$	38,524,536	$	—	$	—	$	38,524,536

Concentrations of Credit Risk and Off-Balance Sheet Risk

Comprehensive Income (Loss)

Furniture and Equipment

Leases

Recent Accounting Pronouncements

No other new accounting pronouncement recently issued or newly effective had or is expected to have a material impact on the Company’s condensed consolidated financial statements.

Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2020

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 June 30, 2020 and December 31, 2019, are summarized below:

	Fair Value Measurements Using
	Level 1		Level 2		Level 3		Total
June 30, 2020
Assets:
Cash and cash equivalents	$	44,864,284	$	—	$	—	$	44,864,284
Total assets	$	44,864,284	$	—	$	—	$	44,864,284
December 31, 2019
Assets:
Cash and cash equivalents	$	38,524,536	$	—	$	—	$	38,524,536
Total assets	$	38,524,536	$	—	$	—	$	38,524,536

Accounts Payable and Accrued Expenses (Tables)

6 Months Ended

Jun. 30, 2020

Payables And Accruals [Abstract]

Schedule of Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses are as follows:

	June 30,		December 31,
	2020		2019
Accrued retention bonus	$	918,944	$	521,859
Accounts payable		622,658		439,785
Accrued project costs		389,854		382,131
Professional fees		355,602		346,999
Accrued bonus		318,591		689,830
Restructuring accrual (see Note 12)		278,846		793,913
Accrued vacation		79,820		43,470
Other		29,913		13,463
Total accounts payable and accrued expenses	$	2,994,228	$	3,231,450

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes the stock option activity during the six months ended June 30, 2020:

	Stock Option Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value
Outstanding, January 1, 2020		5,335,850		$	2.60		6.23	$	2,866
Granted		962,720			0.71
Exercised		—			—
Expired/cancelled		(1,452,470	)		4.01
Outstanding, June 30, 2020		4,846,100		$	1.80		7.39	$	1,014,874
Expected to vest, June 30, 2020		2,295,314		$	1.56		8.98	$	678,430
Options exercisable, June 30, 2020		2,550,786		$	2.02		5.97	$	336,444

Summary of Recognized Compensation Cost Related to Stock-Based Compensation Activity

The Company recognized the following compensation cost related to stock-based compensation activity for the periods presented:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Research and development	$	176,110	$	73,463	$	371,899	$	232,794
General and administrative		132,231		531,198		263,909		993,552
Total	$	308,341	$	604,661	$	635,808	$	1,226,346

Stock Options Valuation Assumptions

The calculation was based on the following assumptions.

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020	2019
Expected term (years)		5.50		5.82	5.92	5.77
Risk-free interest rate	0.38%		2.21%		0.53%	2.32%
Expected volatility	74.82%		65.97%		69.36%	65.83%
Expected dividend yield	0.00%		0.00%		0.00%	0.00%

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

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Net and Comprehensive Income (Loss) per Share

	Three Months Ended June 30,					Six Months Ended June 30,
	2020		2019			2020		2019
Numerator:
Net and comprehensive income (loss) per share	$	9,276,032	$	(5,683,616	)	$	5,357,369	$	(14,176,441	)
Denominator:
Weighted average common shares used in computing EPS
Basic		40,588,004		40,588,004			40,588,004		40,588,004
Diluted		40,905,288		40,588,004			40,747,960		40,588,004

Basic and diluted EPS	$	0.23	$	(0.14	)	$	0.13	$	(0.35	)

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

	Six Months Ended June 30,
	2020		2019
Options to purchase common stock		4,846,100		6,771,807
Warrants to purchase common stock		600,000		317,562

Leases (Tables)

6 Months Ended

Jun. 30, 2020

Leases [Abstract]

Summary of Lease Cost and Information Related to the Right-of-Use Assets and Operating Lease Liabilities

The following table presents the lease cost and information related to the right-of-use assets and operating lease liabilities:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020			2019
Lease cost
Average rent expense	$	28,357	$	62,085	$	56,715		$	124,140

Other information
Cash paid for amounts included in the measurement of operating lease liabilities	$	29,145	$	62,154	$	58,290		$	124,308

The weighted average remaining lease term and discount rate at June 30, 2020
Weighted-average remaining lease term - operating leases						1.08
Weighted-average discount rate - operating leases						13.28	%

Schedule of Future Payments Related to Operating Leases Activities

As of June 30, 2020, future payments related to operating leases activities are presented in the table below:

	2020		2021		2022 and Thereafter		Total Lease Payments
Operating leases	$	59,490	$	69,685	$	—	$	129,175
Less interest								(8,167	)
Present value of lease liabilities							$	121,008

Nature of Organization and Operations - Additional Information (Detail)		1 Months Ended
	May 12, 2020 USD ($)	Jun. 30, 2020 USD ($) Patient	May 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
One-time payment received	$ 15,000,000		$ 15,000,000
Cash and cash equivalents		$ 44,864,284		$ 38,524,536
Razuprotafib [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of patients dosed in clinical trial \| Patient		195
Period of treatment		28 days
Latanoprost Ophthalmic [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Percentage of dosage for patients enrolled in trial		0.005%

Summary of Significant Accounting Policies - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2020 USD ($) Segment	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segment \| Segment	1
Uncertain tax positions	$ 0		$ 0
One-time cumulative adjustment upon adoption	$ 42,600,459	$ 33,006,494	$ 36,535,343	$ 45,716,480	$ 50,795,435		$ 58,666,575
ASU 2018-07 [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Summary Of Significant Accounting Policies [Line Items]
One-time cumulative adjustment upon adoption						$ 5,717
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
Certificates of Deposits [Member]
Summary Of Significant Accounting Policies [Line Items]
Short-term investments	$ 100,000

Summary of Significant Accounting Policies - Schedule of Assets Measured on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Assets:
Cash and cash equivalents	$ 44,864,284	$ 38,524,536
Total assets	44,864,284	38,524,536
Level 1 [Member]
Assets:
Cash and cash equivalents	44,864,284	38,524,536
Total assets	$ 44,864,284	$ 38,524,536

Accounts Payable and Accrued Expenses - Schedule of Accounts Payable and Accrued Expenses (Detail) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued retention bonus	$ 918,944	$ 521,859
Accounts payable	622,658	439,785
Accrued project costs	389,854	382,131
Professional fees	355,602	346,999
Accrued bonus	318,591	689,830
Restructuring accrual (see Note 12)	278,846	793,913
Accrued vacation	79,820	43,470
Other	29,913	13,463
Total accounts payable and accrued expenses	$ 2,994,228	$ 3,231,450

Common Stock - Additional Information (Detail) - USD ($)		6 Months Ended	12 Months Ended
	Oct. 14, 2019	Jun. 30, 2020	Dec. 31, 2019	Mar. 15, 2020
Equity [Abstract]
Common stock, shares authorized		300,000,000	300,000,000
Common stock, par value		$ 0.0001	$ 0.0001
Dividends common stock declared or paid		$ 0
Warrants outstanding		600,000	917,562
Number of warrants issued to purchase common stock	600,000		317,562
Warrants exercise price per share	$ 0.486		$ 5.00
Warrants term			3 years
Warrants vesting period	6 months
Warrants expiration date		Oct. 24, 2024	Mar. 15, 2020
Number of warrants expired				317,562

Preferred Stock - Additional Information (Detail) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Temporary Equity Disclosure [Abstract]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 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		6 Months Ended
	Mar. 31, 2020	May 31, 2019	Mar. 31, 2017	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jan. 01, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options to purchase common stock, granted						962,720
Unrecognized compensation cost related to stock options				$ 2,108,948		$ 2,108,948
Weighted-average fair value of options granted				$ 0.76		$ 0.43
Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period						48 months
Weighted average period expected to be recognized						1 year 11 months 23 days
2017 Stock Option and Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares available for issuance			4,600,000					1,623,520
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				3,570,705		3,570,705			1,983,093
Term of options to be granted						10 years
Shares issued for special retention grant		2,419,050
Options to purchase common stock, granted				260,720	2,801,600	962,720	4,622,428
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%
2017 Stock Option and Incentive Plan [Member] \| Stock Option [Member] \| First Installment [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage		50.00%
Option, vesting date		Jun. 30, 2020
2017 Stock Option and Incentive Plan [Member] \| Stock Option [Member] \| Second Installment [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage		50.00%
Option, vesting date		Jun. 30, 2021

Stock-Based Compensation - Summary of Stock Option Activity (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding at beginning balance \| shares	5,335,850
Shares, Granted \| shares	962,720
Shares, Expired/cancelled \| shares	(1,452,470)
Shares, Outstanding at ending balance \| shares	4,846,100	5,335,850
Shares, Expected to vest \| shares	2,295,314
Shares, Options exercisable \| shares	2,550,786
Weighted Average Exercise Price, Outstanding at beginning balance \| $ / shares	$ 2.60
Weighted Average Exercise Price, Granted \| $ / shares	0.71
Weighted Average Exercise Price, Expired/cancelled \| $ / shares	4.01
Weighted Average Exercise Price, Outstanding at ending balance \| $ / shares	1.80	$ 2.60
Weighted Average Exercise Price, Expected to vest \| $ / shares	1.56
Weighted Average Exercise Price, Options exercisable \| $ / shares	$ 2.02
Weighted Average Remaining Contractual Term, Outstanding	7 years 4 months 20 days	6 years 2 months 23 days
Weighted Average Remaining Contractual Term, Expected to vest	8 years 11 months 23 days
Weighted Average Remaining Contractual Term, Options exercisable	5 years 11 months 19 days
Aggregate Intrinsic Value, Outstanding \| $	$ 1,014,874	$ 2,866
Aggregate Intrinsic Value, Expected to vest \| $	678,430
Aggregate Intrinsic Value, Options exercisable \| $	$ 336,444

Stock-Based Compensation - Summary of Recognized Compensation Cost Related to Stock-Based Compensation Activity (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 308,341	$ 604,661	$ 635,808	$ 1,226,346
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	176,110	73,463	371,899	232,794
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 132,231	$ 531,198	$ 263,909	$ 993,552

Stock-Based Compensation - Stock Options Valuation Assumptions (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term (years)	5 years 6 months	5 years 9 months 25 days	5 years 11 months 1 day	5 years 9 months 7 days
Risk-free interest rate	0.38%	2.21%	0.53%	2.32%
Expected volatility	74.82%	65.97%	69.36%	65.83%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Current income tax expense or benefit	$ 0	$ 0	$ 0	$ 0
Deferred income tax expense or benefit	$ 0	$ 0	$ 0	$ 0

Net and Comprehensive Income (Loss) Per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Net and Comprehensive Income (Loss) Per Share (Detail) - USD ($)	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net and comprehensive income (loss) per share	$ 9,276,032	$ (3,918,663)	$ (5,683,616)	$ (8,492,825)	$ 5,357,369	$ (14,176,441)
Weighted average common shares used in computing EPS
Basic	40,588,004		40,588,004		40,588,004	40,588,004
Diluted	40,905,288		40,588,004		40,747,960	40,588,004
Basic and diluted EPS	$ 0.23		$ (0.14)		$ 0.13	$ (0.35)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Net and Comprehensive Income (Loss) Per Share Attributable to Common Stockholders - Schedule of Weighted Average Common Stock Equivalents Excluded from Calculation of Basic and Diluted Net and Comprehensive Income (Loss) per Share (Detail) - Weighted Average [Member] - shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average common stock equivalents excluded from calculation of basic and diluted net and comprehensive income (loss) per share	4,846,100	6,771,807
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average common stock equivalents excluded from calculation of basic and diluted net and comprehensive income (loss) per share	600,000	317,562

Leases - Additional Information (Detail) - USD ($)	3 Months Ended
Leases - Additional Information (Detail) - USD ($)	Dec. 31, 2019	Jun. 30, 2020
Leases [Abstract]
Penalties incurred on termination of leases	$ 0
Lease arrangements, renewal term		5 years

Leases - Summary of Lease Cost and Information Related to the Right-of-Use Assets and Operating Lease Liabilities (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Lease cost
Average rent expense	$ 28,357	$ 62,085	$ 56,715	$ 124,140
Other information
Cash paid for amounts included in the measurement of operating lease liabilities	$ 29,145	$ 62,154	$ 58,290	$ 124,308
The weighted average remaining lease term and discount rate
Weighted-average remaining lease term - operating leases	1 year 29 days		1 year 29 days
Weighted-average discount rate - operating leases	13.28%		13.28%

Leases - Schedule of Future Payments Related to Operating Leases Activities (Detail)	Jun. 30, 2020 USD ($)
Leases [Abstract]
Operating leases, 2020	$ 59,490
Operating leases, 2021	69,685
Total Lease Payments	129,175
Less interest	(8,167)
Present value of lease liabilities	$ 121,008

Employee Stock Purchase Plan - Additional Information (Detail) - shares	Jun. 20, 2018	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding		4,846,100		5,335,850
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		350,000
Percentage of annual increase in number of shares reserved for issuance	1.00%

License Agreement - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended	6 Months Ended
	May 12, 2020	May 31, 2020	Jun. 30, 2020	Jun. 30, 2020
Revenue From Contract With Customer [Abstract]
Payment received from license agreement	$ 15,000,000	$ 15,000,000
Revenue recognized			$ 15,000,000	$ 15,000,000
Revenue, Product and Service [Extensible List]			arpo:LicenseRevenueMember	arpo:LicenseRevenueMember
Maximum amount of milestone payments eligible to receive under license agreement				$ 40,000,000
Maximum amount of sales milestone payments eligible to receive under license agreement				$ 50,000,000
Percentage of payments received				20.00%

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Restructuring - Additional Information (Detail) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost And Reserve [Line Items]
Remaining liability related to severance	$ 278,846	$ 793,913		$ 278,846
Accounts Payable and Accrued Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Remaining liability related to severance	300,000	800,000		300,000
Workforce Reduction [Member]
Restructuring Cost And Reserve [Line Items]
Realignment plan, employee severance expense		$ 1,000,000	$ 900,000		$ 900,000
Cash payments against severance liability	$ 300,000			$ 600,000

Subsequent Event - Additional Information (Detail) - ATM [Member] - Sales Agreement [Member] - Common Stock [Member] - Cantor [Member] - USD ($)	Aug. 05, 2020	Feb. 21, 2018
Subsequent Event [Line Items]
Aggregate maximum offering price of shares		$ 75,000,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Net proceeds from sale of shares	$ 2,300,000
Sale of shares of common stock	1,480,000
Expenses related to sale of shares	$ 186,000
Subsequent Event [Member] \| Sales Agent Compensation [Member]
Subsequent Event [Line Items]
Expenses related to sale of shares	$ 75,000