Understanding biology to tackle the disease: Multiple myeloma from bench to bedside, and back.

Multiple myeloma (MM) is a cancer of antibody-producing plasma cells. The pathognomonic laboratory finding is a monoclonal immunoglobulin or free light chain in the serum and/or urine in association with bone marrow infiltration by malignant plasma cells. MM develops from a premalignant condition, monoclonal gammopathy of undetermined significance (MGUS), often via an intermediate stage termed smoldering multiple myeloma (SMM), which differs from active myeloma by the absence of disease-related end-organ damage. Unlike MGUS and SMM, active MM requires therapy. Over the past 6 decades, major advancements in the care of MM patients have occurred, in particular, the introduction of novel agents (ie, proteasome inhibitors, immunomodulatory agents) and the implementation of hematopoietic stem cell transplantation in suitable candidates. The effectiveness and good tolerability of novel agents allowed for their combined use in induction, consolidation, and maintenance therapy, resulting in deeper and more sustained clinical response and extended progression-free and overall survival. Previously a rapidly lethal cancer with few therapeutic options, MM is the hematologic cancer with the most novel US Food and Drug Administration-approved drugs in the past 15 years. These advances have resulted in more frequent long-term remissions, transforming MM into a chronic illness for many patients.