Efficacy of daratumumab-based therapies in patients with relapsed, refractory multiple myeloma treated outside of clinical trials

Outside of clinical trials, experience with daratumumab-based combination therapies (DCTs) using bortezomib (V)/lenalidomide (R)/pomalidomide (P), and dexamethasone (d) in relapsed/refractory multiple myeloma (RRMM) is limited. We reviewed the outcomes of 126 patients who received ≥ 1 cycle of any DCT. Median age at DCT initiation was 67 (range, 43-93) years. High-risk cytogenetics was present in 33% patients. Median number of prior therapies was 4 (range, 1-14) and time to first DCT from diagnosis was 4.3 years (range, 0.4-13.0). Seventeen (13%) patients were refractory to single agent daratumumab. Fifty-two (41%), 34 (27%), 23 (18%), and 17 (14%) received DPd, DRd, DVd and “other” DCTs, respectively. Overall response rate was 47%. Median follow-up was 5.5 months (95% CI, 4.2-6.1). Median progression-free survival (PFS) was 5.5 months (95% CI, 4.2-7.8). Median overall survival was not reached (NR) with any regimen. Median PFS (months) was worst for penta-refractory MM (n = 8) vs quadruple refractory MM (n = 18) and others (n = 100) (2.2 [95% CI, 1-2.4] vs 3.1 [95% CI, 2.1-NR] vs 5.9 [95% CI, 5.0-NR]; P <.001); those who were refractory to ≥1 agents used in the DCT vs others (4.9 [95% CI, 3.1-6.0] vs 8.2 [95% CI, 4.6-NR]; P =.02); and those who received >2 prior therapies vs others (5.0 months [95% CI, 3.7-5.9] vs NR [95% CI, NR-NR]; P =.002). Non-hematologic toxicities included infections (38%), fatigue (32%), and infusion reactions (18%). Grade 3 or higher hematological toxicities were seen in 41% of patients. DCTs are effective in RRMM. ORR and PFS in heavily pretreated patients are lower than those reported in clinical trials.