Nature of Organization and Operations	3 Months Ended
Mar. 31, 2019
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 complications of diabetes. In March 2019, the Company announced the top line results of its AKB-9778 Phase 2b (TIME-2b) clinical trial initiated in June 2017 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. While the Company believed AKB-9778 had the potential to slow down or possibly reverse retinal vascular changes caused by diabetes, the subcutaneous administration of AKB-9778 twice daily did not meet the study’s primary endpoint of increasing the percentage of patients with an improvement of two or more steps in diabetic retinopathy severity score in the study eye, compared to placebo. However, the Company did see encouraging data in a number of prespecified, key secondary endpoints related to the changes in the Urine Albumin-Creatinine Ratio, a measure of kidney function, and in reducing intraocular pressure. As a result, the Company plans to advance a topical drop formulation of AKB-9778 into clinical development as a potential treatment for open-angle glaucoma and expects to initiate a Phase 1b clinical trial in the second quarter of 2019 with results anticipated by the end of 2019. In addition, the Company’s pipeline program, ARP-1536, a humanized monoclonal antibody directed at the same target as 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. 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). 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 March 31, 2019 and 2018, include the accounts of the Company and its wholly owned subsidiary, Aerpio Therapeutics, LLC. 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 Bio., Inc, during 2018. Future revenue is dependent on the terms of the license agreement with Gossamer Bio., Inc as further described in Footnote 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 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. The Company’s inability to obtain required funding in the near future could have a material adverse effect on its operations and strategic development plan for future growth. If the Company cannot successfully raise additional capital and implement its strategic development plan, its liquidity, financial condition and business prospects will be materially and adversely affected, and the Company may have to cease operations. Based on the Company’s current cash reserves of $53.4 million at March 31, 2019 and financial condition as of this Quarterly Report on Form 10-Q, we believe our existing cash and cash equivalent will be sufficient to fund currently planned operations at least through the second quarter of fiscal year 2021.

Nature of Organization and Operations

3 Months Ended

Mar. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

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 complications of diabetes. In March 2019, the Company announced the top line results of its AKB-9778 Phase 2b (TIME-2b) clinical trial initiated in June 2017 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. While the Company believed AKB-9778 had the potential to slow down or possibly reverse retinal vascular changes caused by diabetes, the subcutaneous administration of AKB-9778 twice daily did not meet the study’s primary endpoint of increasing the percentage of patients with an improvement of two or more steps in diabetic retinopathy severity score in the study eye, compared to placebo. However, the Company did see encouraging data in a number of prespecified, key secondary endpoints related to the changes in the Urine Albumin-Creatinine Ratio, a measure of kidney function, and in reducing intraocular pressure. As a result, the Company plans to advance a topical drop formulation of AKB-9778 into clinical development as a potential treatment for open-angle glaucoma and expects to initiate a Phase 1b clinical trial in the second quarter of 2019 with results anticipated by the end of 2019.

In addition, the Company’s pipeline program, ARP-1536, a humanized monoclonal antibody directed at the same target as 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.

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). 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 March 31, 2019 and 2018, include the accounts of the Company and its wholly owned subsidiary, Aerpio Therapeutics, LLC.

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 Bio., Inc, during 2018. Future revenue is dependent on the terms of the license agreement with Gossamer Bio., Inc as further described in Footnote 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 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.

The Company’s inability to obtain required funding in the near future could have a material adverse effect on its operations and strategic development plan for future growth. If the Company cannot successfully raise additional capital and implement its strategic development plan, its liquidity, financial condition and business prospects will be materially and adversely affected, and the Company may have to cease operations. Based on the Company’s current cash reserves of $53.4 million at March 31, 2019 and financial condition as of this Quarterly Report on Form 10-Q, we believe our existing cash and cash equivalent will be sufficient to fund currently planned operations at least through the second quarter of fiscal year 2021.