Rigel Pharmaceuticals Inc. has announced updated data from its ongoing Phase 1b clinical study evaluating R289, an oral prodrug of R835 and a dual IRAK1/4 inhibitor, in patients with relapsed or refractory lower-risk myelodysplastic syndrome (MDS). The data were presented by Dr. Guillermo Garcia-Manero during an oral session at the 67th American Society of Hematology $(ASH)$ Annual Meeting and Exposition held December 6-9, 2025. According to the company, R289 continues to be generally well tolerated. Preliminary efficacy was observed at doses of 500 mg or greater once daily, with 33% of evaluable transfusion dependent patients achieving red blood cell transfusion independence (RBC-TI). The ongoing study is assessing safety, tolerability, pharmacokinetics, and preliminary efficacy, with the dose expansion phase currently enrolling patients to determine the recommended Phase 2 dose. Rigel anticipates selecting this dose for future clinical studies in the second half of 2026. R289 has received Orphan Drug and Fast Track designations from the U.S. FDA for the treatment of myelodysplastic syndromes.
Disclaimer: This news brief was created by Public Technologies (PUBT) using generative artificial intelligence. While PUBT strives to provide accurate and timely information, this AI-generated content is for informational purposes only and should not be interpreted as financial, investment, or legal advice. Rigel Pharmaceuticals Inc. published the original content used to generate this news brief via EDGAR, the Electronic Data Gathering, Analysis, and Retrieval system operated by the U.S. Securities and Exchange Commission (Ref. ID: 0001104659-25-119976), on December 10, 2025, and is solely responsible for the information contained therein.
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