Rigel Pharmaceuticals doses first patient in Phase 1b study of R289

Rigel Pharmaceuticals announced it dosed the first patient in its Phase 1b study of R289, an IRAK1/4 dual inhibitor, in patients with lower-risk myelodysplastic syndromes who are refractory or resistant to prior therapies. Rigel’s open-label, Phase 1b study of R289 is expected to enroll approximately 22 patients with lower-risk MDS who are refractory or resistant to prior therapies. The primary objective of the study is safety, with secondary and exploratory objectives to assess preliminary efficacy and characterize the pharmacokinetic and pharmacodynamic profile of R289. The safety and efficacy data from this Phase 1b study, along with the safety and PK/PD data from the completed first-in-human study in heathy volunteers, are intended to be used to determine the recommended Phase 2 dose for future clinical development of R289 targeting lower-risk MDS.