FDA Places Clinical Hold on Pacritinib for Myelofibrosis

Nick Mulcahy

February 10, 2016

The US Food and Drug Administration (FDA) had placed a full clinical hold on pacritinib (CTI BioPharma), an investigational agent for the treatment of myelofibrosis.

All clinical trial patients currently on pacritinib must discontinue the agent immediately, and no patients can be enrolled or start pacritinib as initial or crossover treatment.

CTI BioPharma said that it has withdrawn its New Drug Application until it can review safety and efficacy data from the PERSIST-2 phase 3 clinical trial and "decide next steps."

In a February 8 letter, the FDA noted that interim overall survival results from PERSIST-2 show a detrimental effect on survival consistent with  results from a previous trial, PERSIST-1. The causes of death in PERSIST-2 include intracranial hemorrhage, cardiac failure, and cardiac arrest in pacritinib-treated patients.

According to a statement from the company, the FDA is currently recommending that CTI BioPharma conduct dose-exploration studies, submit final study reports and datasets for PERSIST-1 and PERSIST-2, provide certain notifications, revise relevant statements in the related Investigator's Brochure and informed consent documents, and make certain modifications to protocols.

All clinical investigators worldwide have been delivered notice of the full clinical hold, which followed an earlier partial clinical hold.

At the 2015 annual meeting of the American Society of Clinical Oncology (ASCO), pacritinib was lauded as potentially addressing an unmet need in myelofibrosis because the agent demonstrated efficacy even in patients with very low platelet counts, for whom there is currently no other approved therapy.

Only one drug, ruxolitinib (Jakafi, Incyte), is currently approved by the FDA for myelofibrosis, but it is not safe for patients with low platelet counts, pacritinib investigator Ruben A. Mesa, MD, from the Mayo Clinic Cancer Center in Scottsdale, Arizona, said at the ASCO meeting.

About one-third of patients with myelofibrosis have low platelet counts, Dr Mesa noted at that time, adding that these patients tend to have shorter survival and are at higher risk for leukemic transformations.

Myelofibrosis affects about 20,000 people in the United States. The disease develops when the bone marrow does not make enough normal blood cells, so the spleen takes over blood cell production and becomes enlarged. Patients often experience tiredness, weakness, shortness of breath, fever, and weight loss. In about one-third of patients, myelofibrosis transforms into acute leukemia, according to 2015 ASCO meeting press materials.


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