The role of JAK inhibitors in multiple myeloma.

Multiple myeloma (MM) is the most common primary malignancy of the bone marrow. No established curative treatment is currently available for patients diagnosed with MM. In recent years, new and more effective drugs have become available for the treatment of MM. Many newer drugs have been evaluated together and in combination with older agents. However, even in combination with other active MM agents, the responses are transient, and; thus, therapeutic approaches to help overcome resistance to these drugs are necessary. Recently, the Janus kinase (JAK) family of tyrosine kinases, including JAK1 and JAK2, has been shown to play a role in the pathogenesis of MM. Preclinical studies have demonstrated that the JAK1/2 inhibitor ruxolitinib, in combination with lenalidomide and dexamethasone, reduces proliferation of the MM cell lines and primary tumor cells derived from MM patients, and this inhibition is greater when these drugs are combined than with single agents. Clinically, early results from the oral treatment regimen of ruxolitinib, corticosteroids (methylprednisolone), and lenalidomide for patients with relapsed/refractory disease are encouraging in terms of safety and efficacy, and additional studies will provide further support for this promising new therapeutic approach for patients with MM.