Selinexor and Pacritinib in JAK Inhibitor-naïve MF Patients With Cytopenias

This Phase II, multicenter, open-label will evaluate the safety and efficacy of pacritinib and selinexor in JAK inhibitor naïve patients with anemia and thrombocytopenia. Participants will receive pacritinib monotherapy for 1 cycle (4 weeks) and will be assessed for qualification to proceed to combination therapy at Cycle 2 Day 1. Participants who qualify for combination therapy will receiving pacritinib and selinexor for the remaining cycles. Participants who do not qualify at Cycle 2 Day 1 will have weekly assessments and count checks. If they meet criteria for combination therapy at any point, selinexor will be added onto pacritinib. Participants who do not qualify for combination therapy by Cycle 4 Day 1 will complete 6 cycles of pacritinib monotherapy, complete primary endpoint assessments after 24 weeks, and discontinue study participation. Participants receiving combination therapy must demonstrate clinical benefit at Cycle 7 Day 1 (24 weeks) to continue receiving therapy until loss of response, disease progression, unacceptable toxicity, participant/physician withdrawal, or the study is terminated.