The development, safety and efficacy of pacritinib for the treatment of myelofibrosis

Introduction: Dysregulation of janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway has been described in myelofibrosis (MF). Currently, there is an unmet need for agents that have the benefit of JAK inhibition, yet also are safe and effective in patients with thrombocytopenia. Areas covered: We discuss the various preclinical and clinical studies describing pacritinib, a selective JAK2/FLT3 inhibitor. So far, it has shown promising results, without significant thrombocytopenia. A PubMed search, using keywords ‘pacritinib’, ‘SB 1518’ and ‘myelofibrosis’ was conducted. Published abstracts from recent national and international meetings were also reviewed for unpublished data. Expert commentary: Currently, pacritinib is on hold by Food and Drugs Administration. It would be imperative to understand if there is a treatment related toxicity that would limit its use. If a safe path is found for this agent, it could have a significant benefit in various settings, based on the data so far.