Daratumumab monotherapy compared with historical control data in heavily pretreated and highly refractory patients with multiple myeloma: An adjusted treatment comparison

Daratumumab is a human CD38-directed monoclonal antibody approved in the United States as monotherapy for patients with multiple myeloma (MM) who have received ≥3 prior lines of therapy (LOTs), including a proteasome inhibitor (PI) and an immunomodulatory agent (IMiD) or who are double refractory to a PI and an IMiD, and in combination with lenalidomide/dexamethasone or bortezomib/dexamethasone for patients with MM who have received ≥1 prior LOT. This study compared the efficacy of daratumumab monotherapy versus historical controls through adjusted treatment comparison. Patient-level data were pooled from two daratumumab monotherapy studies (16 mg/kg; GEN501 and SIRIUS) and two independent US databases (IMS LifeLink and OPTUM), which reflect treatments used in real-world patients with MM who received ≥3 prior LOTs or were double refractory to a PI and an IMiD. Using a multivariate proportional hazards regression model, the relative treatment effect of daratumumab versus historical controls was estimated, adjusting for imbalances in characteristics between cohorts. Baseline characteristics that differed between patients treated with daratumumab (N = 148) and historical control (N = 658) were prior treatment with pomalidomide (55% vs 15%) or carfilzomib (41% vs 28%) and triple/quadruple refractory status (64% vs 14%). The adjusted overall survival-hazard ratio (OS-HR) for daratumumab versus historical control was 0.33 (95% confidence interval, 0.24-0.46) compared with 0.46 (0.35-0.59) for unadjusted HR. Impact of adjustment was mainly driven by refractory status and prior pomalidomide/carfilzomib exposure. This adjusted treatment comparison suggests that daratumumab demonstrates improved OS compared with historical control data in heavily pretreated and highly refractory MM patients.