Acer Therapeutics and Relief Therapeutics Announce U.S. FDA Approval of OLPRUVA™ for Patients with Urea Cycle Disorders

Acer Therapeutics Inc. (Nasdaq: ACER) (Acer) and its collaboration partner, RELIEF THERAPEUTICS Holding SA (SIX: RLF, OTCQB: RLFTF, RLFTY) (Relief), today announced that the U.S. Food and Drug Administration (FDA) has approved OLPRUVA (sodium phenylbutyrate) for oral suspension in the U.S. for the treatment of certain patients living with urea cycle disorders (UCDs) involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS).

The FDAs approval of OLPRUVA, an innovative formulation of sodium phenylbutyrate packaged for the first time in single-dose envelopes, marks the culmination of our ongoing dedication to develop new and differentiated treatment options for those affected by rare diseases, said Chris Schelling, chief executive officer and founder of Acer. Patients who are living with UCDs now have an alternative treatment option with OLPRUVA, to address some of the challenges they may have with existing therapy. We are pleased to be able to provide a new, approved treatment choice for those living with this challenging disease.

Mr. Schelling continued, This approval represents the first FDA-approved product for Acer, validating our ability to identify and develop treatments where science can be applied in novel ways and make them available to patients as quickly and efficiently as possible. In addition, this approval unlocks our Marathon debt funding option and provides us with resources to advance our pipeline of investigational product candidates.

The daily challenges of living with a UCD can be overwhelming and emotionally draining for patients and their families, said Tresa Warner, president of the National Urea Cycle Disorders Foundation. We welcome new treatment options that can help patients, caregivers and their healthcare teams manage UCDs.

OLPRUVAs approval triggers the availability of a $42.5 million term loan to Acer under the previously announced March 2022 loan agreement the Company entered into with affiliates of Marathon Asset Management L.P. If Acer requests and receives the loan proceeds, management believes it will have sufficient resources to fund current operations into H2 2023.

OLPRUVA has been approved as an oral suspension by the FDA for the treatment of patients with UCDs. UCDs are a group of rare, genetic disorders that can cause harmful ammonia to build up in the blood, potentially resulting in brain damage and neurocognitive impairments, if ammonia levels are not controlled.1 Any increase in ammonia over time is serious. Therefore, it is important to adhere to any dietary protein restrictions and have alternative medication options to help control ammonia levels.

This FDA approval is a significant milestone for patients with UCDs in the U.S., offering an additional choice to manage their condition, added Jack Weinstein, chief executive officer of Relief. We look forward to building on OLPRUVAs approval in the U.S. and expanding its availability into other territories outside of the U.S.

OLPRUVA received FDA approval under section 505(b)(2) of the Federal Food, Drug and Cosmetic Act (FDCA), a regulatory pathway that allows applicants to rely, at least in part, on third party data for approval. In its New Drug Application (NDA), Acer cited preclinical and clinical safety and efficacy data from the reference listed drug (RLD), BUPHENYL powder, which is approved as adjunctive therapy in the chronic management of patients with UCDs involving deficiencies of CPS, OTC or AS. In its NDA, Acer also provided additional data including studies that evaluated the bioavailability and bioequivalence of OLPRUVA compared to BUPHENYL powder. The data from these studies, presented at the Society for Inherited Metabolic Disorders (SIMD) Annual Meeting in April 2022 and the Genetic Metabolic Dieticians International (GMDI) Conference in May 2022, showed that OLPRUVA was bioequivalent to BUPHENYL powder.

Commitment to Patient Access

Acer intends to offer Navigator by Acer Therapeutics, a suite of integrated patient support services designed to facilitate access to therapy. Navigator by Acer Therapeutics is designed to assist UCD patients with support, access, education, and adherence.

Financial Outlook

Acer is not currently providing specific revenue or operating expense guidance for OLPRUVA. Based on current forecasted operating expenses and revenue, and assuming receipt of the $42.5 million term loan funds from its March 2022 term loan arrangement with Marathon (less the amount to repay the bridge loan and fees), and Acers existing cash and equivalents, Acer believes its cash resources will be sufficient to fund its operations into H2 2023. Further information with respect to Acers March 2022 term loan arrangement, as well as a bridge loan facility (as amended in August 2022) and a convertible note financing which also funded in March 2022 can be found in the SEC Filings section of Acers website.

About OLPRUVA

OLPRUVA is a prescription medicine used along with certain therapy, including changes in diet, for the long-term management of adults and children weighing 44 pounds (20 kg) or greater and with a body surface area (BSA) of 1.2 m2 or greater, with urea cycle disorders (UCDs), involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC) or argininosuccinic acid synthetase (AS). OLPRUVA is not used to treat rapid increase of ammonia in the blood (acute hyperammonemia), which can be life-threatening and requires emergency medical treatment.

Important Safety Information

Certain medicines may increase the level of ammonia in your blood or cause serious side effects when taken during treatment with OLPRUVA. Tell your doctor about all the medicines you or your child takes especially if you or your child takes corticosteroids, valproic acid, haloperidol, and/or probenecid. OLPRUVA can cause serious side effects, including: 1) nervous system problems (neurotoxicity). Symptoms include sleepiness, tiredness, lightheadedness, vomiting, nausea, headache, confusion, 2) low potassium levels in your blood (hypokalemia) and 3) conditions related to swelling (edema). OLPRUVA contains salt (sodium), which can cause swelling from salt and water retention. Tell your doctor right away if you or your child get any of these symptoms. Your doctor may do certain blood tests to check for side effects during treatment with OLPRUVA. If you have certain medical conditions such as heart, liver or kidney problems, are pregnant/planning to get pregnant or breast-feeding, your doctor will decide if OLPRUVA is right for you.

The most common side effects of OLPRUVA include absent or irregular menstrual periods, decreased appetite, body odor, bad taste or avoiding foods you ate prior to getting sick (taste aversion). These are not all of the possible side effects of OLPRUVA. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

For additional Important Safety Information, see full Prescribing Information, Patient Information and discuss with your doctor.

About Acer Therapeutics Inc.

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. In the U.S., OLPRUVA (sodium phenylbutyrate) is approved for the treatment of urea cycle disorders (UCDs) involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS). Acer is also advancing a pipeline of investigational product candidates for rare and life-threatening diseases, including: OLPRUVA (sodium phenylbutyrate) for treatment of various other inborn errors of metabolism, including Maple Syrup Urine Disease (MSUD); ACER-801 (osanetant) for treatment of induced Vasomotor Symptoms (iVMS) and Post-traumatic Stress Disorder (PTSD); EDSIVO (celiprolol) for treatment of vascular Ehlers-Danlos syndrome (vEDS) in patients with a confirmed type III collagen (COL3A1) mutation; and ACER-2820 (emetine), a host-directed therapy against a variety of viruses, including cytomegalovirus, Zika, dengue, Ebola and COVID-19. In March 2021, Acer entered into a Collaboration and License Agreement with Relief for development and commercialization of OLPRUVA in which Acer retains development and commercialization rights in the U.S., Canada, Brazil, Turkey, and Japan. For more information, visit www.acertx.com .

About RELIEF THERAPEUTICS Holding SA

RELIEF THERAPEUTICS Holding SA is a Swiss, commercial-stage, biopharmaceutical company focused on identification, development and commercialization of novel, patent protected products intended for the treatment of rare and ultra-rare diseases including metabolic disorders, pulmonary diseases and connective tissue disorders. Reliefs diversified pipeline consists of assets with the potential to effectively address significant unmet medical needs, including PKU GOLIKE, engineered with the proprietary Physiomimic technology, which is the first prolonged-release amino acid product commercialized for the dietary management of phenylketonuria (PKU). Relief has a collaboration and license agreement with Acer Therapeutics for the worldwide development and commercialization of ACER-001 (sodium phenylbutyrate) for the treatment of various inborn errors of metabolism, including urea cycle disorders (UCDs) and maple syrup urine disease (MSUD). Relief also continues to develop aviptadil for several rare pulmonary indications. Further, Relief is in clinical development for APR-TD011, a differentiated acid oxidizing solution of hypochlorous acid intended for the treatment of epidermolysis bullosa (EB), a group of rare, genetic, life-threatening connective tissue disorders; A