Safety considerations when treating myelofibrosis.

INTRODUCTION: Myelofibrosis (MF) is a clonal disorder leading to marrow fibrosis, cytopenias and extramedullary haematopoiesis.

AREAS COVERED: Generic management of MF with a specific focus on the efficacy and safety profile of the Janus Kinase (JAK)1/JAK 2 kinase inhibitor, ruxolitinib (Novartis Pharmaceuticals, Basel, Switzerland), will be discussed. This agent has manageable haematological side effects and possesses both beneficial and potentially detrimental immunosuppressive effects. Multiple JAK inhibitors are in various stages of development but some have been withdrawn due to unexpected toxicities such as the occurrence of Wernicke's encephalopathy (Fedratinib; Sanofi, Paris). Traditional therapies such as hydroxycarbamide, interferon, immunomodulatory drugs and androgens will also be discussed.

EXPERT OPINION: Therapeutic options in MF have expanded with the introduction of JAK inhibitors. Ruxolitinib benefits many patients with symptomatic MF. Other JAK inhibitors such as momelotinib may have the additional benefit of alleviating anaemia. Unfortunately, there is no current JAK inhibitor option for patients with severe thrombocytopenia as pacritinib was recently put on clinical hold due to adverse events. Careful consideration needs to be given towards optimal management of patients who lose their response/are resistant to JAK inhibitor therapies and those with a high risk mutational status but lower risk prognostic score.