CTI BioPharma Corp. announced two poster presentations from the Company's pacritinib program at the Society of Hematologic Oncology (SOHO) Tenth Annual Meeting, to be held in Houston, Texas and virtually September 28 – October 1, 2022. A new data analysis from the Phase 3 PERSIST-2 trial and an in vitro analysis of pacritinib, a novel JAK2/IRAK1 inhibitor approved by the U.S. FDA for patients with myelofibrosis and a platelet count below 50 x 109/L, will highlight pacritinib's impact on anemia and inhibition of Activin A receptor type 1 (ACVR1).

Retrospective Analysis of Anemia Benefit of Pacritinib from the PERSIST-2 Trial: Abstract Number: MPN-145; Session Name: Poster Session; Session Date: September 28; Presentation Time: 5:05-6:30 p.m. CDT (06:05-7:30 p.m. EDT); Presenter: Dr. Stephen Oh. Pacritinib is a novel JAK2/IRAK1 inhibitor approved by the U.S. Food and Drug Administration (FDA) for patients with myelofibrosis and severe thrombocytopenia (platelet count <50 x 109/L). Previous clinical trials have noted improvements in spleen volume and symptom scores, as well as improvement in anemia and a decline in transfusion burden.

A retrospective analysis of the Phase 3 PERSIST-2 trial was conducted to further assess pacritinib's impact on anemia, and an in vitro analysis was performed to explore pacritinib's inhibition of Activin A receptor type 1 (ACVR1; also known as activin receptor-like kinase 2 [ALK2]). On duplicate assays, pacritinib was shown to be a more potent inhibitor of ACVR1 compared to momelotinib, with a half maximal inhibitory concentration (IC50) of 10.8 and 22.6 nM versus34.9 and 70.2 nM, respectively. The percentage of patients who achieved transfusion independence over any 12-week intervals through week 24 was greater on pacritinib 200 mg twice daily than best available therapy (27% vs 7%), among evaluable non-transfusion independent patients (defined as any red blood cell transfusions in 90 days prior to the first dose or a baseline hemoglobin <8 g/dL).

These data suggest an important role for pacritinib in addressing anemia in patients with myelofibrosis. Retrospective Comparison of Patient Outcomes on Pacritinib Versus Ruxolitinib in Patients with Myelofibrosis (MF) and Thrombocytopenia (encore): Abstract Number: MPN-141; Session Name: Poster Session; Session Date: September 28; Presentation Time: 5:05-6:30 p.m. CDT (06:05-7:30 p.m. EDT); Presenter: Dr. Prithviraj Bose. Pacritinib is a novel JAK2/IRAK1 inhibitor approved by the U.S. FDA for patients with myelofibrosis and severe thrombocytopenia (platelet count <50 x 109/L).

Unlike the JAK 1/2 inhibitor ruxolitinib, which must be dose-reduced or held in patients with thrombocytopenia, pacritinib has been studied at full dose regardless of platelet count. This retrospective analysis reported on the outcomes in patients treated with pacritinib versus ruxolitinib in the Phase 3 PERSIST-2 study. Patients were randomized 1:1:1 to pacritinib 200 mg BID, pacritinib 400 mg once daily (QD) or BAT, with 45% of patients on BAT receiving ruxolitinib.

Results show that pacritinib, administered at the full dose of 200 mg BID, yielded higher response rates and a similar safety profile compared to lower-dose ruxolitinib in patients with myelofibrosis who have moderate or severe thrombocytopenia.