Smoldering Multiple Myeloma: Emerging Concepts and Therapeutics

Smoldering multiple myeloma (SMM) is a pre-malignant condition with an inherent risk for progression to multiple myeloma (MM). The 2014 IMWG guidelines define smoldering multiple myeloma as a monoclonal gammopathy disorder with serum monoclonal protein (IgG or IgA) ≥30 g/L or urinary monoclonal protein ≥500 mg per 24 h and/or clonal bone marrow plasma cells 10–60 % without any myeloma-defining events or amyloidosis. The risk for progression of SMM to MM vary based on clinical, laboratory, imaging, and molecular characteristics. Observation, with periodic monitoring is the current standard of care for SMM. Over last few years, research advances in SMM have led to the delineation of newer risk factors for progression and identification of a “high-risk” group that would potentially benefit from early treatment. This review focuses on advances in the SMM risk-stratification model and recent clinical trials in this patient population.