Pacritinib and its use in the treatment of patients with myelofibrosis who have thrombocytopenia

The treatment landscape for myelofibrosis (MF) has reached the molecular era by targeting different pathways that are implied in this myeloproliferative neoplasm. A few years ago, the first-in-class JAK1/JAK2 inhibitor ruxolitinib, demonstrated reductions in both constitutional symptoms and splenomegaly, leading to the US FDA approval. The development or worsening of cytopenias in patients receiving ruxolitinib uncovered an unmet need that has been addressed by alternative approaches. Pacritinib, a dual JAK2 and FLT3 inhibitor which also inhibits IRAK1, has demonstrated the ability to favorably impact MF-associated splenomegaly and symptom burden, while having limited myelosuppression with manageable gastrointestinal toxicity. Herein, we provide an overview of pacritinib, from early preclinical studies to the latest and ongoing PAC203 trial, as an emerging therapy for MF.