Circulating Tumor DNA in Multiple Myeloma: Current Insights and Future Perspectives.

Circulating tumor DNA (ctDNA) has emerged as a promising minimally invasive biomarker in multiple myeloma (MM), providing dynamic insight into tumor burden, clonal evolution and molecular heterogeneity. Unlike conventional bone marrow-based diagnostics, ctDNA analysis offers a systemic approach to disease assessment and may better reflect spatially heterogeneous and extramedullary disease. Recent advances in highly sensitive molecular techniques, including digital droplet polymerase chain reaction and next-generation sequencing, have improved the feasibility of ctDNA detection and longitudinal disease monitoring in MM. Increasing evidence demonstrates substantial concordance between ctDNA and bone marrow genomic profiles, while also highlighting the ability of ctDNA to identify resistant subclones, molecular relapse and genomic evolution during therapy. ctDNA has shown potential clinical utility in molecular profiling, therapeutic monitoring and minimal residual disease assessment. ctDNA may become increasingly relevant in the era of novel immunotherapies, including chimeric antigen receptor T-cell therapy and bispecific antibodies. Despite these promising applications, several biological and technical limitations still restrict routine clinical implementation, including low ctDNA concentration in patients with minimal disease burden and lack of methodological standardization. Overall, ctDNA represents a rapidly evolving tool with significant potential to improve personalized disease monitoring and therapeutic strategies in MM.