Early Intervention With a Curative Intent Through an Intensive Therapy Versus Immunologic Disease Control Using a Minimal Intensity Approach in the Management of High-risk Smoldering Multiple Myeloma: A Systematic Review of Evidence From Clinical Trials

Abstract

A subset of individuals with smoldering myeloma (SMM) are at a high risk of progression to symptomatic myeloma. Current efforts are focused on identifying this high-risk group and intercepting the disease process before its progression. There is no consensus on what the goal of an intervention should be, whether to aim for a cure through a high-intensity intervention or pursue immunologic disease control using the least intense approach. This systematic review summarized current evidence in support of the optimum approach. A database search of Medline/PubMed, Scopus, EMBASE, Web of Science, CINAHL, Wiley Cochrane Library, clinicaltrials.gov, and conference proceedings of ASH, EHA, ASCO, ESMO was performed. Results were presented using narrative synthesis of quantitative data. Of the 2088 identified records, a total of 10 eligible studies made up of 6 minimal-intensity clinical trials, 3 moderate-intensity trials, and 1 high-intensity trial were included in this review with a total demographic population of 588 high-risk SMM patients. Minimal intensity lenalidomide-based regimen demonstrated clinical effectiveness in delaying disease progression and improving overall survival in high-risk SMM. The single-agent monoclonal antibodies did not have any major impact on improving overall survival, although the studies were not powered to do so. There is a marked increase in the depth of response as the intensity of treatment increases without a proportional improvement in overall survival. Moderate- and high-intensity interventions yielded similar minimal residual disease negativity rates and overall survival. The minimal, moderate, and high-intensity approaches all demonstrated clinical benefits in delaying disease progression and improving overall survival in patients with high-risk SMM and increasing intensity of intervention does not necessarily translate to improved overall survival.

Keywords: Autologous stem cell transplantation; Daratumumab; Elotuzumab; Isatuximab; Lenalidomide.