Acer Therapeutics and Relief Therapeutics Announce ACER-001 IND Submission for the Treatment of Maple Syrup Urine Disease

Relief Therapeutics Holding SA / Key word(s): Regulatory Admission Acer Therapeutics and Relief Therapeutics Announce ACER-001 IND Submission for the Treatment of Maple Syrup Urine Disease 28-Jul-2022 / 07:05 CET/CEST Release of an ad hoc announcement pursuant to Art. 53 LR The issuer is solely responsible for the content of this announcement. Acer Therapeutics and Relief Therapeutics Announce ACER-001 IND Submission for the Treatment of Maple Syrup Urine Disease

Phase 2a trial initiation planned for the first half of 2023 subject to IND clearance and available capital

NEWTON, MA and GENEVA, SWITZERLAND – July 28, 2022 – Acer Therapeutics Inc. (Nasdaq: ACER) (Acer) and its collaboration partner, RELIEF THERAPEUTICS Holding SA (SIX: RLF, OTCQB: RLFTF, RLFTY) (Relief), today announced the submission of an Investigational New Drug (IND) application to the U.S. Food and Drug Administration (FDA) to evaluate the efficacy and safety of ACER-001 (sodium phenylbutyrate) for the potential treatment of patients with maple syrup urine disease (MSUD).

MSUD is a rare, life-threatening metabolic disorder caused by a deficiency in an enzyme complex that metabolizes branched chain ketoacids, the breakdown products of the three branched-chain amino acids (BCAAs), leucine, valine, and isoleucine. Left untreated, MSUD leads to elevated plasma concentrations of these amino acids, which can lead to chronic and acute neurological damage, ranging from developmental delays in children, seizures, cognitive challenges and in some cases death. Currently, the only treatment option for patients with MSUD is a life-long, protein-restricted diet.

“We are very pleased to expand ACER-001’s clinical development into a second rare disease, and one for which there are currently no approved pharmacologic therapies,” said Adrian Quartel, MD, FFPM, Chief Medical Officer of Acer. “Even with strict dietary management, people with MSUD still remain at serious risk for a wide range of life-threatening complications. We look forward to the initiation of this investigational trial and learning more about ACER-001’s potential to reduce branched-chain amino acids, and specifically leucine levels, in MSUD patients.”