FDA Expands Review of Pacritinib for Treatment of Myelofibrosis with Severe Thrombocytopenia


CTI BioPharma’s new drug application had already received priority review. The date for PDUFA was November 30.

On November 30, the FDA extended the review period for pacritinib, a new therapy to treat adult patients with intermediate or high risk primary or secondary myelofibrosis with severe thrombocytopenia. The action date of the Prescription Drug User Fee Act (PDUFA) has been extended by 3 months until February 28, 2022, according to a statement from CTI Biopharma Corp.1

The FDA previously granted a priority review for the New Drug Application (NDA) for patients with myelofibrosis, with a PDUFA date of November 30. During discussions for the drug’s label, the agency requested additional data, which, according to CTI BioPharma’s statement, was submitted on November 24. According to CTI BioPharma, the FDA declared the submission a “major amendment,” triggering the extension to allow for further review. In its statement, CTI said the company was not aware of any major deficiencies in the application.

“CTI continues to work constructively with the FDA when reviewing our NDA,” said Adam R. Craig, MD, PhD, president and CEO of CTI BioPharma, in the release. “We are committed to providing patients with cytopenia myelofibrosis with a new treatment option as soon as possible and are confident in the potential of pacritinib to set a new standard of care.”

Pacritinib, an oral kinase inhibitor specific for JAK2, IRAK1 and CSF1R, received priority review based on the results of a pair of phase 3 trials, PERSIST-2 (NCT02055781) and PERSIST -1 (NCT01773187), as well as an earlier study that examined the efficacy of pacritinib in patients with severe thrombocytopenia.2

PERSIST-2 involved 311 patients and showed pacritinib 200 mg taken twice daily to be significantly more effective than the best available therapies, including ruxolitinib. It should be noted that a reduction in spleen size of at least 35% was seen in 29% of people taking pacritinib, compared to only 3% of those taking the best available treatment.3

In PERSIST-1, researchers found pacritinib to be well tolerated; patients who took it experienced a significant reduction in spleen size and reduced myelofibrosis symptoms. The most common Grade 3/4 adverse reactions up to week 24 of pacritinib treatment were anemia (17%), thrombocytopenia (12%) and diarrhea (5%).4

The company is planning several presentations at the next American Society of Hematology meeting in Atlanta, scheduled for December 10-14.

The references

  1. CTI BioPharma announces the extension of the FDA review period for pacritinib in myelofibrosis with severe thrombocytopenia. Press release. CTI BioPharma. Accessed November 30, 2021. https://bit.ly/3G2XO3m
  2. CTI BioPharma announces the acceptance of the NDA granted with the priority review of pacritinib for the treatment of patients with myelofibrosis. Press release. CTI BioPharma. June 1, 2021. Accessed November 27, 2021. https://bit.ly/3cQZGj4
  3. Mascarenhas J, Hoffman R, Talpaz M, et al. Pacritinib vs the best available treatment, including ruxolitinib, in patients with myelofibrosis. JAMA Oncol. 2018; 4 (5): 652-659. doi: 10.1001 / jamaoncol.2017.5818
  4. Mesa RA, Vannucchi AM, Mead A, et al. Pacritinib versus best available therapy for the treatment of myelofibrosis independent of baseline cytopenias (PERSIST-1): an international, randomized, phase 3 trial. Lancet Haematol. 2017; 4 (5): e225-e236. doi: 10.1016 / S2352-3026 (17) 30027-3


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