Dr. Mesa on the FDA Approval of Pacritinib in Intermediate- or High-Risk Myelofibrosis With Severe Thrombocytopenia

Ruben A. Mesa, MD, director of the Mays Cancer Center at UT Health San Antonio MD Anderson Cancer Center, discusses the FDA approval of pacritinib (Vonjo) for patients with myelofibrosis and severe thrombocytopenia.

On February 28, 2022, the FDA granted an accelerated approval to pacritinib for the treatment of adult patients with intermediate or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis with a platelet count below 50 × 10⁹/L.

The regulatory decision will have an immediate effect on the treatment of this patient population and will likely be incorporated into the National Comprehensive Cancer Network guidelines for myelofibrosis management, Mesa explains.

Based on the safety and efficacy data from the phase 3 PERSIST-1 trial (NCT01773187), pacritinib will have a role as frontline therapy for patients with myelofibrosis and marked thrombocytopenia, Mesa says. Ruxolitinib (Jakafi) and fedratinib (Inrebic) have been used off-label for patients with myelofibrosis whose platelet counts are greater than 50,000 μL, but they are typically given at a significantly reduced dose. Pacritinib can be given at full dose for this patient population, Mesa explains. Pacritinib also has a role in the frontline treatment of patients with anemia.

In the second-line setting, pacritinib could become preferred to ruxolitinib and fedratinib to treat patients with thrombocytopenia and/or anemia, Mesa says.

Ultimately, although the approval will likely affect treatment guidelines and clinical options for patients with myelofibrosis, the field will have to gain experience in managing the toxicities associated with pacritinib and individual use with the agent based on cytopenias, Mesa concludes.