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Rigel Presents Updated Data from the Ongoing Phase 1b Study Evaluating R289 in Patients with Lower-Risk MDS at the 67th ASH Annual Meeting and Exposition
Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL), a commercial stage biotechnology company focused on hematologic disorders and cancer, today announced updated data from its ongoing Phase 1b study evaluating R2891, an oral prodrug of R835, a potent and selective dual inhibitor of interleukin receptor-associated kinases 1 and 4 (IRAK1/4), in patients with relapsed or refractory (R/R) lower-risk myelodysplastic syndrome (MDS). The data are being presented today in an oral session by Dr. Guillermo Garcia
About this update from Rigel Pharmaceuticals, Inc.
[{"type":"list","items":[{"val":[{"type":"text","content":"R289 continues to be generally well tolerated and at doses of ≥500 mg QD preliminary efficacy was observed in elderly, heavily pre-treated lower-risk MDS patients","length":162,"tagName":"p"}]},{"val":[{"type":"text","content":"RBC-TI was achieved by 33% (6/18) of evaluable transfusion dependent patients receiving R289 doses ≥500 mg QD, including 40% (2/5) in the 500 mg BID dose group","length":159,"tagName":"p"}]}],"tagName":"ul","bulletedList":true,"length":321,"olType":false},{"type":"text","content":"SOUTH SAN FRANCISCO, Calif., Dec. 7, 2025 /PRNewswire/ -- Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL), a commercial stage biotechnology company focused on hematologic disorders and cancer, today announced updated data from its ongoing Phase 1b study evaluating R2891, an oral prodrug of R835, a potent and selective dual inhibitor of interleukin receptor-associated kinases 1 and 4 (IRAK1/4), in patients with relapsed or refractory (R/R) lower-risk myelodysplastic syndrome (MDS). The data are being presented today in an oral session by Dr. Guillermo Garcia-Manero at the 67th American Society of Hematology (ASH) Annual Meeting and Exposition being held December 6-9, in Orlando, Florida and virtually.","length":714,"tagName":"p"},{"type":"text","content":""New therapies are needed for patients with transfusion dependent lower-risk MDS. We're pleased to share these updated study results, which underscore the potential of R289 to become a treatment option for these patients," said Lisa Rojkjaer, M.D., Rigel's chief medical officer. "We look forward to concluding the dose expansion phase of the study and anticipate selection of the recommended Phase 2 dose for future clinical studies in the second half of 2026."","length":490,"tagName":"p"},{"type":"text","content":"Rigel's open-label Phase 1b study of R289 is evaluating the safety, tolerability, pharmacokinetics and preliminary efficacy in patients with R/R lower-risk MDS (NCT05308264). Enrollment in the dose escalation phase of the study was completed in July 2025. In October 2025, the first patient was dosed in the dose expansion phase where up to 40 patients will be randomized to either 500 mg once or twice daily to determine the recommended Phase 2 dose for future clinical trials.","length":482,"tagName":"p"},...