pacritinib

Pacritinib is an oral small molecule kinase inhibitor used to treat adults with intermediate or high-risk primary or secondary myelofibrosis, particularly in patients with severe thrombocytopenia (platelet count below 50 × 10⁹/L). It selectively inhibits Janus kinase 2 (JAK2), including the mutant JAK2V617F form, as well as FMS-like tyrosine kinase 3 (FLT3), interleukin-1 receptor-associated kinase 1 (IRAK1), and colony-stimulating factor 1 receptor (CSF1R). Pacritinib does not inhibit JAK1 at clinically relevant concentrations. By blocking these kinases, it disrupts abnormal signaling pathways that drive excessive inflammation and proliferation in myelofibrosis. The drug was developed for patients who are not candidates for other JAK inhibitors due to low platelet counts. Pacritinib received accelerated FDA approval in February 2022 based on its ability to reduce spleen volume; continued approval may depend on confirmatory clinical benefit.

Brand names

Vonjo

Other names

pacritinib citrate