'JAK-ing' up the treatment of primary myelofibrosis: Building better combination strategies

Purpose of review The article discusses the promising agents that are approved or currently under investigation for the treatment of myelofibrosis and reviews the ongoing Janus kinase (JAK) inhibitors-based combinatorial strategies in this setting. Recent findings Myelofibrosis is a Philadelphia-negative myeloproliferative neoplasm with constitutive JAK/STAT activation. The JAK-inhibitor ruxolitinib is the only approved drug for this disease in the United States and Europe based on two randomized phase III studies that demonstrated clinically meaningful reduction in spleen size, improvement in symptoms, quality of life, and an overall survival advantage with prolonged follow-up. Emerging data have revealed the complex molecular architecture of myelofibrosis with clonal evolution playing a central role in disease progression or transformation. These molecular pathways may explain the heterogeneous benefits obtained by JAK-inhibitors in patients with myelofibrosis. In addition, the genetic and epigenetic mutations appear to work in concert with overactive JAK/STAT signaling and contribute to myelofibrosis pathogenesis and prognosis, suggesting a potential to exploit them as potential therapeutic targets. Summary Combining JAK-inhibitors with agents that target parallel prosurvival pathways or agents that enhance hematopoiesis may enhance efficacy and/or mitigate on-target myelosuppression, thereby extending the therapeutic benefits observed with JAK-inhibitors alone.