Rigel Announces One Oral and Four Poster Presentations at the 67th American Society of Hematology Annual Meeting and Exposition

Core Insights - Rigel Pharmaceuticals is set to present data from its ongoing Phase 1b study of R289, a dual IRAK1/4 inhibitor, at the 67th American Society of Hematology (ASH) Annual Meeting on December 7, 2025, focusing on patients with relapsed or refractory lower-risk myelodysplastic syndrome (MDS) [1][2][5] - The ASH Annual Meeting will also feature four poster presentations regarding REZLIDHIA (olutasidenib) for treating relapsed or refractory mutated isocitrate dehydrogenase-1 (mIDH1) acute myeloid leukemia (AML) [1][5] R289 Study Details - The Phase 1b study of R289 has enrolled 33 patients as of July 15, 2025, with a median age of 75 and a median of 3 prior therapies; 61% of these patients had a high transfusion burden at baseline [6] - R289 was administered at doses ranging from 250 mg once daily to 500 mg twice daily, with the most common treatment-emergent adverse events being diarrhea (28.1%), constipation (25%), and increased creatinine/ALT (21.9%) [6] - Among evaluable transfusion-dependent patients receiving doses of at least 500 mg, 31% achieved durable red blood cell transfusion independence for over 8 weeks, with a median time to onset of 2.2 months and a median duration of 24.3 weeks [6] REZLIDHIA Data Highlights - In a pivotal cohort of the Phase 2 registrational study involving 147 patients with R/R mIDH1 AML, 24% maintained stable disease after two treatment cycles, with a subsequent response rate of 33% [9] - The median overall survival for late responders was reported at 23.9 months, indicating that patients with stable disease after two cycles may benefit from continued treatment [9][10] - The overall response rate in a real-world cohort of olutasidenib-treated patients was 50%, supporting its use as a viable therapeutic option in post-venetoclax treatment settings [9][10] Company Overview - Rigel Pharmaceuticals, Inc. is a biotechnology company focused on developing therapies for hematologic disorders and cancer, founded in 1996 and based in South San Francisco, California [26]