Relief Therapeutics Announces Positive Results from Pivotal Bioequivalence Study of RLF-OD032

“We are extremely pleased to have advanced RLF-OD032 from concept to clinical validation in just three years, demonstrating its bioequivalence and confirming its potential as the first ready-to-use liquid sapropterin formulation,” said Giorgio Reiner, chief scientific officer of Relief. “We believe this innovation will make a meaningful difference for individuals living with PKU, and we are now focused on completing the final regulatory steps to bring this product to market as quickly as possible.”

RLF-OD032 offers a novel approach to PKU management by addressing key limitations of current sapropterin therapies that must be mixed with large volumes of water. As a ready-to-use, highly concentrated liquid, RLF-OD032 can be administered directly, without water, offering a portable, low-volume, and patient-friendly alternative. Its up to 100-fold reduction in dose volume simplifies daily treatment and is expected to improve adherence, optimize outcomes, and enhance quality of life for children and adults living with PKU.

Relief plans to proceed with final data verification and completion of CMC activities in preparation for submission of a 505(b)(2) New Drug Application (NDA). The NDA is expected to be filed in early 2026, seeking U.S. marketing approval for the treatment of PKU, and will be subject to a 10-month FDA review under the 505(b)(2) pathway.

ABOUT RLF-OD032 RLF-OD032 is an innovative, ready-to-use, portable and highly concentrated formulation of sapropterin dihydrochloride in liquid suspension for oral administration, designed to lower blood phenylalanine levels in adult and pediatric PKU patients. It offers a more patient-friendly solution by significantly reducing the volume of medication required compared to current formulations. This advancement aims to enhance compliance, particularly among pediatric patients, who often struggle with the high volumes associated with existing sapropterin treatments. If approved, RLF-OD032 would be the first and only portable, ready-to-use liquid formulation of sapropterin dihydrochloride, with pending patent protection extending through at least 2043.

ABOUT PHENYLKETONURIA Phenylketonuria (PKU) is a genetic disorder caused by a deficiency of the enzyme needed to break down phenylalanine (Phe), leading to a toxic buildup of Phe from the consumption of foods containing protein or aspartame. Individuals with PKU lack the ability to metabolize Phe, which is present in many foods. Without treatment, PKU can cause severe neurological and developmental issues. The standard treatment involves a lifelong phenylalanine-restricted diet supplemented with amino acid-based, phenylalanine-free medical foods to prevent protein deficiency and optimize metabolic control. However, this diet is highly restrictive and often creates barriers to social interaction, limiting compliance and increasing the risk of poor disease management.

ABOUT RELIEF Relief is a commercial-stage biopharmaceutical company dedicated to advancing treatment paradigms and improving the lives of patients with rare and debilitating diseases. With core expertise in drug delivery systems and drug repurposing, Relief's clinical pipeline includes innovative treatments designed to address critical unmet medical needs in rare dermatological, metabolic and respiratory conditions. The Company has also successfully brought several approved products to market through licensing and distribution partnerships. Headquartered in Geneva, Relief is listed on the SIX Swiss Exchange under the symbol RLF and quoted in the U.S. on OTCQB under the symbols RLFTF and RLFTY. For more information, visit www.relieftherapeutics.com.

CONTACT: RELIEF THERAPEUTICS Holding SA Jeremy Meinen Chief Financial Officer contact@relieftherapeutics.com

DISCLAIMER This press release contains forward-looking statements, which may be identified by words such as "believe," "assume," "expect," "intend," "may," "could," "will," or similar expressions. These statements are based on current plans and assumptions and are subject to risks and uncertainties that could cause actual results, financial condition, performance, or achievements to differ materially from those expressed or implied. Such factors include, but are not limited to, changes in economic conditions, market developments, regulatory changes, competitive dynamics, and other risks or changes in circumstances. The clinical results described herein are based on a pre-database lock analysis and remain subject to confirmation upon completion of final data verification and database lock. This communication is provided as of the date hereof, and Relief undertakes no obligation to update any forward-looking statements contained herein as a result of new information, future events or otherwise.

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