Cancer Network recently featured a press release by CTI BioParma announcing that the FDA has given accelerated approval for pacritinib to treat patients diagnosed with myelofibrosis and severely low platelets (thrombocytopenia). The FDA approval for pacritinib (Vonjo) was based on a 200 mg twice daily dose.
Primary myelofibrosis is a rare disease that usually affects the elderly. The disease is characterized by a buildup of scar tissue (fibrosis) in the bone marrow. Median survival is about four to five years.
The FDA based its decision on results from the PERSIST-2 Phase 3 study involving 311 patients.
Patients receiving a 200 mg dose of pacritinib saw a thirty-five percent reduction in spleen volume after twenty-four months. This compares favorably against three percent of patients receiving the best therapy available.
The FDA included a stipulation in its post-approval for pacritinib. PACIFICA, a Phase 3 clinical trial must be completed, and results announced, by 2025.
PAC293 is a phase 2 dose-finding trial assessing pacritinib against ruxolitinib for patients with myelofibrosis and severe thrombocytopenias. Interim results showed that participants dosed with pacritinib at 200 mg two times each day had the highest spleen volume reduction. Their total reduction in symptom volume was also the highest.
Dr. John Mascarenhas at the Tisch institute commented in a press release that myelofibrosis plus severe thrombocytopenia results in poor overall survival. Dr. Mascarenhas said that thus far there have been few available treatments.
Patients were divided into three groups testing either a once-daily dose versus a twice-daily dose or the best therapy available. There was not a significant difference with respect to overall survival between the three groups. However, treatment with pacritinib resulted in a twenty-five percent reduction in symptoms in pacritinib cohorts versus fourteen percent in the control group.
At week twenty-four, adverse events were anemia, thrombocytopenia, and diarrhea. Twelve percent of patients in the pacritinib group died and thirteen percent died in the control group.
Patients receiving 200 mg of pacritinib twice daily did not have grade 3 or greater cardiac or hemorrhagic events.
