Rigel Announces First Patient Enrolled in the Dose Expansion Phase of its Phase 1b Study of R289 in Patients with Lower-Risk MDS

Dose expansion phase will determine the recommended Phase 2 dose of R289 for patients with transfusion dependent R/R lower-risk MDS

SOUTH SAN FRANCISCO, Calif., Oct. 8, 2025 /PRNewswire/ -- Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL), a commercial stage biotechnology company focused on hematologic disorders and cancer, today announced the first patient has been enrolled in the dose expansion phase of the ongoing Phase 1b study of R289¹ in patients with relapsed or refractory (R/R) lower-risk myelodysplastic syndrome (MDS). R289 is Rigel's potent and selective dual inhibitor of interleukin receptor-associated kinases 1 and 4 (IRAK1/4).

Read more at prnewswire.com