Phase 1b Study of Pelabresib Added to Stable Ruxolitinib Treatment in Japanese Adults with Myelofibrosis

What this Trial Is About

Researchers are evaluating pelabresib as an addition to ruxolitinib in Japanese adults with myelofibrosis, including primary myelofibrosis and post-polycythemia vera or post-essential thrombocythemia myelofibrosis. This Phase 1b, open-label study aims to assess the safety, how the body processes pelabresib, and early signs of effectiveness in this patient group. Participants will receive a fixed dose of 125 mg pelabresib once daily combined with their stable dose of ruxolitinib 5 to 25 mg twice daily. The study includes screening, treatment until disease progression or other stopping reasons, a 30-day safety follow-up after stopping pelabresib, and a long-term follow-up lasting at least two years after the last dose. Pelabresib dosing will continue without planned dose changes during the safety confirmation period of 21 days. During the study, participants will undergo assessments including monitoring for side effects, blood tests, and imaging to measure spleen size and symptom scores. Safety will be checked closely during treatment and follow-up, including looking for leukemic changes. Long-term follow-up visits occur approximately every 12 weeks for up to three years to monitor health status and treatment effects. The study will continue until all participants complete follow-up or pelabresib becomes available through other access routes.

Study of Pelabresib add-on to Ruxolitinib in Japanese Adult Patients With Myelofibrosis