Acer Therapeutics & Relief Therapeutics Announce NDA Submission for ACER-001 for Treatment of Urea Cycle Disorders

Acer Therapeutics Inc. Relief Therapeutics recently announced the submission of a New Drug Application (NDA) to the US FDA for ACER-001 (sodium phenylbutyrate) for the treatment of Urea Cycle Disorders (UCDs). ACER-001 is a nitrogen-binding agent in development for use as adjunctive therapy in the chronic management of patients with UCDs involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS).

Based on standard FDA review timelines, Acer expects to receive notification from FDA on the potential acceptance of the NDA for filing within 60 days of submission and subsequent substantive review.

The 505(b)(2) NDA submission is supported by results from two previously announced bioequivalence (BE) trials in which ACER-001 showed similar relative bioavailability for both phenylbutyrate (PBA) and phenylacetate (PAA), the active metabolite of sodium phenylbutyrate, compared to BUPHENYL (sodium phenylbutyrate). Acer has also received an Agreement Letter from FDA in response to the company’s initial Pediatric Study Plan (iPSP), which outlines an agreed upon approach that addresses the needs of pediatric patients with UCDs.

“The submission of our NDA for ACER-001 marks an important step toward bringing this potential alternative treatment option to patients with UCDs,” said Chris Schelling, Chief Executive Officer and Founder of Acer. “We look forward to working with the FDA through the review process and will continue advancing our preparations for a potential launch of ACER-001, while also assisting Relief toward regulatory submissions in Europe.”

Jack Weinstein, Chief Financial Officer and Treasurer of Relief Therapeutics, added “We are excited about the progress made to date in support of a potential regulatory approval of ACER-001 for UCDs in the US. With the NDA now submitted, we will continue our efforts to back ACER-001’s development in Europe by targeting submission of a Marketing Authorization Application (MAA) for the treatment of UCDs in Europe by the end of 2021.”

ACER-001 is an investigational product candidate which has not been approved by FDA or the European Medicines Agency (EMA). There is no guarantee that this product candidate will be accepted for substantive review, or if accepted, receive regulatory authority approval in any territory, or become commercially available for the indications under investigation.

UCDs are a group of disorders caused by genetic mutations that result in a deficiency in one of the six enzymes that catalyze the urea cycle, which can lead to an excess accumulation of ammonia in the bloodstream, a condition known as hyperammonemia. Acute hyperammonemia can cause lethargy, somnolence, coma, and multi-organ failure, while chronic hyperammonemia can lead to headaches, confusion, lethargy, failure to thrive, behavioral changes, and learning and cognitive deficits. Common symptoms of both acute and chronic hyperammonemia also include seizures and psychiatric symptoms. The current treatment of UCDs consists of dietary management to limit ammonia production in conjunction with medications that provide alternative pathways for the removal of ammonia from the bloodstream. Some patients may also require individual branched-chain amino acid supplementation.

Current medical treatments for UCDs include nitrogen scavengers, RAVICTI and BUPHENYL, in which the active pharmaceutical ingredients are glycerol phenylbutyrate (GPB) and sodium phenylbutyrate, respectively. According to a 2016 study by Shchelochkov et al., published in Molecular Genetics and Metabolism Reports, while nitrogen scavenging medications have been shown to be effective in helping to manage ammonia levels in some patients with UCDs, non-compliance with treatment is common. Reasons referenced for non-compliance associated with some available medications include unpleasant taste, frequency with which medication must be taken, required number of pills, and the high cost of the medication.

ACER-001 (sodium phenylbutyrate) is being developed for the treatment of various inborn errors of metabolism, including UCDs and MSUD. ACER-001 is a nitrogen-binding agent in development for use as adjunctive therapy in the chronic management of patients with UCDs involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS). The formulation is a multi-particulate dosage formulation for oral administration consisting of a core center, a layer of active drug, and a taste-masked coating designed to avoid the bitter taste in the mouth while quickly dissolving in the low pH of the stomach. ACER-001’s taste-masked formulation is aimed to improve the palatability of sodium phenylbutyrate. Acer is also being developed for Maple Syrup Urine Disease (MSUD) and has been granted orphan drug designation by the FDA for the MSUD indication. ACER-001 is an investigational product candidate which has not been approved by FDA or the European Medicines Agency (EMA).

Acer is a pharmaceutical company focused on the acquisition, development and commercialization of therapies for serious rare and life-threatening diseases with significant unmet medical needs. Acer’s pipeline includes four programs: ACER-001 (sodium phenylbutyrate) for treatment of various inborn errors of metabolism, including urea cycle disorders (UCDs) and Maple Syrup Urine Disease (MSUD); EDSIVO™ (celiprolol) for treatment of vascular Ehlers-Danlos syndrome (vEDS) in patients with a confirmed type III collagen (COL3A1) mutation; ACER-801 (osanetant) for treatment of induced Vasomotor Symptoms (iVMS); and ACER-2820 (emetine), a host-directed therapy against a variety of infectious diseases, including COVID-19. Each of Acer’s product candidates is believed to present a comparatively de-risked profile, having one or more of a favorable safety profile, clinical proof-of-concept data, mechanistic differentiation and/or accelerated paths for development through specific programs and procedures established by the FDA. In March 2021, Acer entered into a Collaboration and License Agreement with Relief Therapeutics for development and commercialization of ACER-001. For more information, visit www.acertx.com.

Relief focuses primarily on clinical-stage programs based on molecules with a history of clinical testing and use in human patients or a strong scientific rationale. Relief’s lead drug candidate RLF-100 (aviptadil), a synthetic form of Vasoactive Intestinal Peptide (VIP), is in late-stage clinical testing in the US for the treatment of respiratory deficiency due to COVID-19. As part of its pipeline diversification strategy, in March 2021, Relief entered into a Collaboration and License Agreement with Acer Therapeutics for development and commercialization of ACER-001. ACER-001 is a taste-masked and immediate release proprietary powder formulation of sodium phenylbutyrate (NaPB) for the treatment of Urea Cycle Disorders and Maple Syrup Urine Disease. In addition, Relief’s recently completed acquisition of APR Applied Pharma Research SA brings a diverse pipeline of marketed and development-stage programs. For more information, visit www.relieftherapeutics.com.