Patients with triple-class refractory (TCR) multiple myeloma (MM) have limited treatment options and poor prognoses. This high unmet need has prompted the development of new therapies allowing for improved outcomes for these patients. Recently, new targeted therapies for the treatment of patients with relapsed or refractory MM have been approved based on single-arm clinical trial results. Real-world (RW) data enable a better understanding of the effectiveness of new therapies in clinical practice and provide external controls for single-arm studies. However, using RW data to identify patients with TCR MM is challenging and subject to limitations.

Daratumumab (dara)-based triplet therapies are commonly used in the second-line (2L) and third-line (3L) settings in relapsed/refractory multiple myeloma (RRMM), usually in combination with dexamethasone and either bortezomib (dara-Vd), carfilzomib (dara-Kd), or pomalidomide (dara-Pd). We performed a real-world (rw) analysis to directly compare these regimens, to our knowledge, for the first time. This was an observational, retrospective cohort study using COTA’s rw database of patients with MM who have initiated 2L or 3L therapy with dara-Vd, dara-Kd, or dara-Pd. rw time to next treatment (rwTTNT) and rw overall survival (rwOS) were analyzed using the Kaplan-Meier method. Comparative analyses were conducted using a trimmed inverse probability of treatment weighting method to control for potential confounders. A total of 639 patients received a dara-based regimen as either 2L or 3L therapy (dara-Vd, n = 201; dara-Kd, n = 122; and dara-Pd, n = 316). A high proportion had functional (52%) or cytogenetic (26%) high-risk disease; 49% were lenalidomide refractory. Median rwTTNT for dara-Vd was 7.6 months and was 12.9 months for dara-Kd (hazard ratio [HR], 0.70; 95% confidence interval [CI], 0.49-0.99). Similarly, median rwTTNT for dara-Vd was 6.9 months and 15.3 months for dara-Pd (HR, 0.57; 95% CI, 0.43-0.77). Median rwTTNT for dara-Pd was 15.7 months, and for dara-Kd 13.2 months (HR, 1.1; 95% CI, 0.8-1.6). No regimen was associated with superior rwOS. Among patients with RRMM receiving 2L or 3L therapy with a dara-based triplet, dara-Vd was associated with inferior rwTTNT compared with both dara-Kd and dara-Pd. dara-Vd may not be a suitable control arm for most phase 3 studies.

Elranatamab efficacy in the single-arm, registrational MagnetisMM-3 trial (NCT04649359) was compared with that of physician’s choice of treatment (PCT) for triple-class refractory multiple myeloma. MagnestisMM-3 eligibility criteria were applied to two USA-based oncology electronic health record databases, COTA and Flatiron Health (FH), to identify cohorts for this study (NCT05932290). Applied statistical techniques accounted for cohort imbalances. MagnetisMM-3 (BCMA-naive; n = 123) outcomes were compared with those from COTA (n = 239) and FH (n = 152). Elranatamab was associated with a significantly higher objective response rate (risk ratios, 1.88–2.25), significantly longer progression-free survival (hazard ratios [HRs], 0.37–0.57), and, across most analyses, significantly longer overall survival (HRs, 0.46–0.66) versus PCT. BCMA-naive patients who were treated with elranatamab exhibited significantly better outcomes than patients treated in real-world clinical practice.