Optimizing current and emerging therapies in multiple myeloma: a guide for the hematologist

Multiple myeloma (MM) is the second most common hematologic malignancy. The diagnosis of MM requires ⩾10% clonal plasma cells in the bone marrow or biopsy-proven plasmacytoma, plus evidence of end-organ damage (hypercalcemia, renal failure, anemia, and lytic bone lesions). The definition of MM has recently been expanded to include a ⩾60% clonal plasma cell burden in the bone marrow, serum involved/uninvolved light chain ratio of ⩾100, or more than one focal lesion on magnetic resonance imaging ⩾5 mm in the absence of end-organ damage. MM is an incurable malignancy previously associated with poor survival rates. However, over the past two decades, the introduction of novel treatment options has resulted in a dramatic improvement in response rates and overall survival (OS). The combination of a proteasome inhibitor and an immunomodulator (IMiD) is the preferred induction treatment for newly diagnosed transplant-eligible MM patients. After induction, high-dose therapy with autologous stem cell transplant (ASCT) is still the standard of care for these patients. In patients who are transplant ineligible, dose adjusted IMiDs or proteasome inhibitor-based combinations are the preferred treatment option. With the recent approval of novel drugs like carfilzomib, ixazomib, pomalidomide, panobinostat, and monoclonal antibodies (elotuzumab and daratumumab), as well as improved understanding of risk stratification, management of comorbidities and treatment side effects, clinicians can optimize anti-MM therapy, particularly in relapse/refractory MM patients. In this review, we outline the current therapeutic approach to the management of MM.