CTI BioPharma Corp. announced that the US Food and Drug Administration (FDA) has accepted its New Drug Application (NDA) for pacritinib as a treatment for myelofibrosis patients with severe thrombocytopenia (platelet counts less than 50 x 109/L), with the NDA being granted Priority Review. The Prescription Drug User Fee Act (PDUFA) target action date is November 30, 2021. The FDA is not currently planning to hold an advisory committee meeting to discuss the NDA.
"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," said Adam R. Craig, M.D., Ph.D., president and chief executive officer of CTI Biopharma. "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."
The NDA was accepted based on the data from the Phase 3 PERSIST-2 and PERSIST-1 and the phase 2 PAC203 clinical trials, with a focus on the severely thrombocytopenic (platelet counts less than 50 x 109/L) patients enrolled in these studies who received pacritinib 200 mg twice a day, including both frontline treatment-naive patients and patients with prior exposure to JAK2 inhibitors. In the PERSIST-2 study, in patients with severe thrombocytopenia who were treated with pacritinib 200 mg twice a day, 29% of patients had a reduction in spleen volume of at least 35%, compared to 3% of patients receiving the best available therapy, which included ruxolitinib.; 23% of patients had a reduction in total symptom scores of at least 50%, compared to 13% of patients receiving the best available therapy. In the same population of patients treated with pacritinib, adverse events were generally low grade, manageable with supportive care, and rarely led to discontinuation. Platelet counts and hemoglobin levels were also stabilized.
Myelofibrosis is a type of bone marrow cancer that results in formation of fibrous scar tissue and can lead to severe thrombocytopenia and anemia, weakness, fatigue and enlarged spleen and liver. Patients with severe thrombocytopenia are estimated to make up one-third of patients treated for myelofibrosis, or approximately 17,000 people in the United States and Europe. Severe thrombocytopenia, defined as blood platelet counts of less than 50 x 109/L, has been shown to result in overall survival rates of just 15 months. Thrombocytopenia in patients with myelofibrosis is associated with the underlying disease but has also been shown to result from treatment with ruxolitinib, which can lead to dose reductions, and as a result, may potentially reduce clinical benefit. Survival in patients who have discontinued ruxolitinib therapy is further compromised, with an average overall survival of seven to 14 months. Myelofibrosis patients with severe thrombocytopenia have limited treatment options, and represent an area of significant area of unmet medical need.
Pacritinib is an investigational oral kinase inhibitor with specificity for JAK2, IRAK1, and CSF1R, but not JAK1. The JAK family of enzymes is 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. In addition to myelofibrosis, the kinase profile of pacritinib suggests its potential therapeutic utility in conditions such as acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia (CMML), and chronic lymphocytic leukemia (CLL), due to its inhibition of c-fms, IRAK1, JAK2 and FLT.
CTI BioPharma Corp is a biopharmaceutical company focused on the acquisition, development and commercialization of novel targeted therapies for blood-related cancers that offer a unique benefit to patients and their healthcare providers.