Cell Therapeutics, Inc. (CTI), a biopharmaceutical company, has reached an agreement with the US Food and Drug Administration (FDA) on a Special Protocol Assessment (SPA) for the planned pivotal phase 3 clinical trial, known as the PERSIST-2 trial, evaluating pacritinib compared to best available therapy, including approved JAK2 inhibitors such as ruxolitinib, in patients with myelofibrosis whose platelet counts are <100,000/uL.  

The SPA is a written agreement between CTI and the FDA regarding the design, endpoints and planned statistical analysis approach of the trial to be used in support of a potential New Drug Application (NDA) submission.  The PERSIST-2 trial is the second of two planned phase 3 clinical trials in patients with myelofibrosis.  CTI expects to initiate the PERSIST-2 clinical trial in the fourth quarter of 2013.

"The FDA worked closely with us to achieve SPA agreement during first cycle review of the PERSIST-2 trial protocol for pacritinib," stated James A. Bianco, CTI's president and CEO.  "As a result of the SPA, which established agreement on trial design to support regulatory approval, we expect that we will be able to initiate this pivotal phase 3 clinical trial of pacritinib by the end of the year.  Myelofibrosis is a chronic disease and JAK inhibitors have had a dramatic impact on the lives of people living with myelofibrosis.  Data from earlier studies of pacritinib showed a clinically meaningful improvement in symptoms with minimal suppression of platelets or red blood cells.  We believe patients with myelofibrosis, particularly those with low platelet counts, could benefit from new treatment options."

PERSIST-2 is a 300 patient randomized, open-label, multi-center pivotal trial in patients with myelofibrosis whose platelet counts are <100,000/uL.  The trial will evaluate pacritinib as compared to best available therapy, including approved JAK2 inhibitors that are dosed according to the product label for myelofibrosis patients with thrombocytopenia.  Patients will be randomized (1:1:1) to receive 200 mg pacritinib twice daily, 400 mg pacritinib once daily or best available therapy.  The agreed upon co-primary endpoints are the percentage of patients achieving a 35 per cent or greater reduction in spleen volume measured by MRI or CT at 24 weeks of treatment and the percentage of patients achieving a Total Symptom Score (TSS) reduction of 50 per cent or greater using six key symptoms as measured by the modified Myelofibrosis Symptom Assessment Form (MF-SAF) diary.  The trial is expected to enroll patients at clinical sites in the United States, Europe and Australia.  

Based on pacritinib's efficacy and tolerability profile demonstrated to date, CTI is pursuing a broad approach to advancing this therapy for myelofibrosis patients by conducting two phase 3 clinical trials: one in a broad set of patients without limitations on blood platelet counts, the PERSIST-1 trial, and the other in patients with low platelet counts, the PERSIST-2 trial, as described above, which is expected to begin in the fourth quarter of 2013.

In January 2013, CTI initiated PERSIST-1, which is a 270 patient randomized, open-label, multicenter phase 3 trial comparing the efficacy and safety of pacritinib with that of best available therapy in patients with myelofibrosis.  Best available therapy includes any physician-selected treatment other than JAK inhibitors and there is no exclusion by patient platelet count.  The trial is currently enrolling patients at clinical sites in Europe, Australia, Russia and the United States.  

Pacritinib is an oral tyrosine kinase inhibitor (TKI) with dual activity against JAK2 and FLT3.  The JAK family of enzymes are a central component in signal transduction pathways, which are critical to normal blood cell growth and development as well as inflammatory cytokine expression and immune responses.  Mutations in these kinases have been shown to be directly related to the development of a variety of blood related cancers including myeloproliferative neoplasms, leukemia and lymphoma.  Pacritinib may offer an advantage over other JAK inhibitors through effective treatment of symptoms while having less treatment-emergent thrombocytopenia and anemia than has been seen in currently approved and in-development JAK inhibitors.

Cell Therapeutics, Inc. is a biopharmaceutical company committed to the development and commercialization of an integrated portfolio of oncology products aimed at making cancer more treatable.