Disease Characteristics and Outcomes of 493 Young Myeloma Patients Treated With Modern Therapies: A Canadian Myeloma Research Group Database Study

BACKGROUND: Young patients ≤ 50 years old with multiple myeloma (MM) account for about 10% of cases and are underrepresented in the literature. METHODS: We explored disease characteristics, treatments, and outcomes following modern therapies of young MM patients using the Canadian Myeloma Research Group (CMRG) database. We included 493 patients ≤ 50 years old diagnosed with MM or plasma cell leukemia without concurrent amyloidosis or POEMS syndrome from January 1, 2010, to July 1, 2022. RESULTS: The median age was 46 years old (range: 25.6-50). Most patients fell into the R-ISS II category (72.7%), and 24.1% had high-risk cytogenetics. The majority of patients (89.9%) received a proteasome inhibitor-based first-line treatment, 92.1% received a stem cell transplant, and 65.6% had maintenance therapy post-autologous stem cell transplant (ASCT). Median follow-up from initial treatment to patients' last follow-up was 48.5 (range: 0-155) months. Median progression-free survival (PFS) was 45.0 months (95% CI: 40.2-50.0). Maintenance therapy post-ASCT improved median PFS to 52.3 months (95% CI: 43.1-68.2), compared to 23.6 months (95% CI: 20.0-34.8) without maintenance [p < 0.001]. CONCLUSION: Although the overall survival has not yet been reached in this young population, our reported median PFS of only 45 months highlights the urgent need to develop innovative treatments to induce more profound and durable responses.