Dr Pemmaraju on Spleen Volume Reduction With Pacritinib in Myelofibrosis

Naveen Pemmaraju, MD, associate professor, Department of Leukemia, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, discusses the importance of introducing pacritinib (Vonjo) to the treatment paradigm for patients with myelofibrosis with low platelet counts.

Dr Pemmaraju on the PERSIST-2 Trial in Myelofibrosis

The phase 3 PERSIST-2 trial (NCT02055781) evaluated the JAK/FLT3 inhibitor pacritinib vs best available therapy (BAT) in patients with myelofibrosis and thrombocytopenia, defined as platelet counts of 100 x 109/L or less. The most common BAT therapies included ruxolitinib (Jakafi) and watchful waiting. Initial results from this trial demonstrated that pacritinib led to a 35% or greater spleen volume reduction (SVR) in 18% of patients vs 3% of patients who received BAT.

PERSIST-2 determined pacritinib to be an effective JAK inhibitor in patients with low platelet counts, Pemmaraju said. These findings are important and fill an unmet need in the thrombocytopenic population, as the other JAK inhibitors approved for patients with myelofibrosis, ruxolitinib and fedratinib (Inrebic), are only indicated for patients with platelet counts of at least 50 x 109/L, Pemmaraju explains.

Dr Pemmaraju on OS With Pacritinib in Myelofibrosis

Findings from the updated overall survival (OS) analysis of PERSIST-2 were presented at the 2023 ASCO Annual Meeting and showed that SVR was associated with an overall survival (OS) benefit in this population. Specifically, patients who received the full study dose of pacritinib and achieved at least a 10% SVR by week 12 experienced a significant OS benefit (P < .0001) compared with those who received BAT (P = .4888).

These OS findings show that pacritinib can induce spleen and symptom improvement, as well as disease modification, Pemmaraju emphasizes. The correlation between spleen/symptom improvement and OS improvement, as shown in PERSIST-2, indicate that JAK inhibitor monotherapies or future combination therapies may help patients live longer with reduced splenomegaly and other physical symptoms, Pemmaraju notes. Similar to previous findings with ruxolitinib, disease modification with pacritinib in patients with myelofibrosis with thrombocytopenia is encouraging and may pave the way for future JAK inhibitor research as well, Pemmaraju concludes.