FDA Grants Priority Review to Pacritinib for Treating Myelofibrosis With Severe Thrombocytopenia

The priority review designation for pacritinib is based off results from 3 trials investigating pacritinib 200 mg twice daily for patients with myelofibrosis and severe thrombocytopenia.

The FDA granted priority review to a new drug application (NDA) for pacritinib as treatment of myelofibrosis with severe thrombocytopenia, according to a press release from the company responsible for the agent, CTI BioPharma Corp.

The decision is informed by results from the phase 3 PERSIST-2 (NCT02055781) and PERSIST-1 (NCT01773187) trials and the phase 2 PAC203 trial (NCT03165734) focusing on patients with severe thrombocytopenia who received pacritinib 200 mg twice a day.

“We are pleased that the FDA’s acceptance of our NDA brings us one step closer to our goal of providing myelofibrosis patients with severe thrombocytopenia a new treatment option,” Adam R. Craig, MD, PhD, President and Chief Executive Officer of CTI Biopharma, said in a press release.1 “With commercial preparation underway, we believe we will be well positioned for a potential U.S. launch later this year. We look forward to working with the FDA during its review of our application.”

In PERSIST-2, 311 patients were analyzed, showing that pacritinib at 200 mg twice daily was significantly more effective in treating patients with myelofibrosis and thrombocytopenia than the existing best available therapies. The results suggest that pacritinib can provide an alternative treatment option for patients whose options are limited.2 Specifically, a reduction in spleen volume of at least 35% was observed in 29% of patients treated with pacritinib compared with only 3% of patients treated with the best available therapy.

“In patients with myelofibrosis and thrombocytopenia, including those with prior anti-JAK therapy, pacritinib twice daily was more effective than BAT, including ruxolitinib [Jakafi], for reducing splenomegaly and symptoms,” wrote the investigators of the PERSIST-2 study.

The results from PERSIST-1 indicated that pacritinib therapy was well tolerated and induced significant spleen volume and symptom reduction among patients with myelofibrosis, irrespective of baseline cytopenias.3 For patients receiving pacritinib therapy, the most common grade 3/4 adverse effects through week 24 of treatment included anemia (17%), thrombocytopenia (12%), and diarrhea (5%).

PAC203 paved the way for the selection of pacritinib at 200 mg twice per day as the recommended dose for the phase 3 study, as the results showed positive clinical activity and an acceptable safety profile.4

This NDA fits a previously unmet medical need for patients with myelofibrosis and severe thrombocytopenia, with a Prescription Drug User Fee Act (PDUFA) Action Date set for November 30, 2021, according to CTI BioPharma.

Pacritinib is an oral kinase inhibitor with specificity for JAK2, IRAK1, and CSF1R. Mutations among these kinases have been shown to associate directly with the development of blood-related cancers, including myeloproliferative neoplasms, leukemia, and lymphoma.

References:

1. CTI BioPharma Announces Acceptance of NDA Granted with Priority Review of Pacritinib for Treatment of Patients with Myelofibrosis. News release. CTI BioPharma Corp. Published June 1, 2021. Accessed June 1, 2021. https://bit.ly/34BNhez

2. Mascarenhas J, Hoffman R, Talpaz M, et al. Pacritinib vs Best Available Therapy, Including Ruxolitinib, in Patients With Myelofibrosis. JAMA Oncol. 2018;4(5):652-659. doi:10.1001/jamaoncol.2017.5818

3. Mesa RA, Vannucchi AM, Mead A, et al. Pacritinib versus best available therapy for the treatment of myelofibrosis irrespective of baseline cytopenias (PERSIST-1): an international, randomised, phase 3 trial. Lancet Haematol. 2017;4(5):e225-e236. doi:10.1016/S2352-3026(17)30027-3

4. Gerds AT, Savona MR, Scott BL, et al. Determining the recommended dose of pacritinib: results from the PAC203 dose-finding trial in advanced myelofibrosis. Blood Adv. 2020;4(22):5825-5835. doi:10.1182/bloodadvances.2020003314