Pacritinib for myelofibrosis in adults with thrombocytopenia

Myelofibrosis is a rare progressive cancer of the bone marrow that disrupts the normal production of healthy blood cells, leading to bone marrow failure. Patients with myelofibrosis and severe thrombocytopenia (platelet count below 50 × 10⁹/L) have a wide range of unmet medical needs compared with those without thrombocytopenia. Usually, these patients have an increased disease burden, increased transfusion dependence, shorter overall survival, and limited treatment options. Pacritinib is a new oral kinase inhibitor specifically targeting Janus kinase 2 (JAK2), interleukin-1 receptor-associated kinase 1 (IRAK-1) and colony-stimulating factor 1 receptor (CSF-1R), and is indicated for the treatment of adults with moderate or high risk of primary or secondary myelofibrosis (post-polycythemia or post-primary thrombocytopenia) whose platelet count is less than 50 × 10⁹/L. In this review, we introduce pacritinib and make a brief comparison of different JAK inhibitors in clinical application.