CTI BioPharma prepares myelofibrosis patients for second phase testing of pacritinib

CTI BioPharma has enrolled 150 patients with myelofibrosis previously treated with ruxolitinibto be tested on pacritinib in the second phase, testing three dosing schedules over 24 weeks. 

The company said it expects to report the determination of the optimal dose of pacritinib – oral tyrosine kinase inhibitor – in mid-2019 following a meeting with the U.S. Food and Drug Administration (FDA). Furthermore, the topline efficacy and safety data are expected in the third quarter of 2019, with the new Phase 3 study targeted to commence enrollment in the third quarter of 2019.

FDA has earlier given the company an input on key elements of the design of a new randomized Phase 3 study of pacritinib in adult patients with myelofibrosis (primary myelofibrosis, post-polycythemia vera myelofibrosis, or post-essential thrombocythemia myelofibrosis) and who have severe thrombocytopenia (as defined by patients with platelet counts of less than 50,000 per microliter), an indication that has been recognized by the medical community as an important unmet medical need. A planned interim safety review by an Independent Data Monitoring Committee (IDMC) is scheduled to occur in the first quarter of 2019, the company said.

CTI BioPharma points out that Pacritinib has demonstrated encouraging results in Phase 1 and 2 studies for patients with myelofibrosis and 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.

Pacritinib has activity against two important activating mutations: Janus Associated Kinase 2 (JAK2) and FMS-like tyrosine kinase 3 (FLT3).

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.

Activating mutations of JAK2 are implicated in certain blood-related cancers, including myeloproliferative neoplasms (MPNs), leukemia and certain solid tumors.

FLT3 is a gene commonly found mutated in patients with acute myeloid leukemia (AML).