FDA Approves Pacritinib For Myelofibrosis With Severe Thrombocytopenia

US Food and Drug Administration

The US Food and Drug Administration (FDA) has approved pacritinib (VONJO) for the treatment of adults with intermediate or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis with a platelet count below 50 x 10⁹/L.

The approval for the rare disease was granted to CTI BioPharma Corp. In the United States, there are approximately 21,000 patients with myelofibrosis, of which 7,000 have severe thrombocytopenia.

The therapy is a novel oral kinase inhibitor with specificity for JAK2 and IRAK1, without inhibiting JAK1, with a recommended dosage of pacritinib is 200 mg orally twice daily. It is the first approved therapy to specifically address the needs of patients with cytopenic myelofibrosis, according to CTI.

"Today's approval of VONJO establishes a new standard of care for myelofibrosis patients suffering from cytopenic myelofibrosis," said John Mascarenhas, MD, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai in a statement. "Myelofibrosis with severe thrombocytopenia, defined as blood platelet counts below 50 × 10⁹/L, has been shown to result in poor survival outcomes coupled with debilitating symptoms. Limited treatment options have rendered this disease as an area of urgent unmet medical need. I am pleased to see that a new, efficacious and safe treatment option is now available for these patients.

The accelerated approval was based on efficacy results from the phase 3 PERSIST-2 study of pacritinib in patients with myelofibrosis. Included patients were randomized 1:1:1 to receive pacritinib 200 mg twice daily, pacritinib 400 mg once daily, or best available therapy. Prior JAK2 inhibitor therapy was permitted in the study.

Findings showed in the cohort of patients treated with pacritinib 200 mg, 29% had a reduction in spleen volume of ≥35% compared to 3% of patients receiving best available therapy, including ruxolitinib.

The most common adverse reactions (≥20%) observed following pacritinib 200 mg twice daily were diarrhea, thrombocytopenia, nausea, anemia, and peripheral edema, while the most frequent serious adverse reactions (≥3%) were anemia, thrombocytopenia, pneumonia, cardiac failure, disease progression, pyrexia, and squamous cell carcinoma of skin.

“With the approval of VONJO, we are excited to now be able to offer a new therapy that is specifically approved for patients with cytopenic myelofibrosis,” said Adam R. Craig, M.D., Ph.D., President and Chief Executive Officer of CTI Biopharma. “We are fully funded for commercial launch, following our debt and royalty transactions with DRI, and we look forward to providing VONJO, the potential best-in-class therapy for cytopenic myelofibrosis patients, to patients within 10 days.”

The release noted as part of the accelerated approval, CTI is required to describe clinical benefit in a confirmatory trial, with the company planning to complete the PACIFICA trial with expected results in 2025.