Rigel reports initial Phase 1b data for R289 in LR-MDS; 40% response rate in evaluable TD patients at ≥500 mg QD

RIGEL PHARMACEUTICALS INC

22 LR-MDS patients enrolled; median age 76, median 3 prior therapies; 73% high transfusion burden.
R289 well tolerated; most common AEs diarrhea/fatigue (27%), chills/nausea/pruritus (23%), all Grade 1/2.
Among evaluable TD patients at doses ≥500 mg QD, 40% (4/10) achieved RBC-TI/HI-E; 3 achieved RBC-TI ≥8 weeks.
Two HTB patients achieved RBC-TI >24 weeks; median RBC-TI duration 29 weeks (range 12.7-51.9 weeks).
FDA granted Fast Track designation for R289 in previously-treated transfusion-dependent LR-MDS.

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