Early Access Program Results From Turkey and a Literature Review on Daratumumab Monotherapy Among Heavily Pretreated Patients With Relapsed/Refractory Myeloma

In countries where frontline drug approval is limited to first-generation proteasome inhibitors or immunomodulatory drugs, relapses have been both more frequent and less durable. We investigated real world data on the efficacy and safety of daratumumab monotherapy among patients with relapsed refractory multiple myeloma (RRMM) from Turkey using a prospective early access program. A total of 42 patients with RRMM after a minimum of 3 previous lines of proteasome inhibitor/immunomodulatory drug-based treatments were included from 25 centers across Turkey. Daratumumab monotherapy was administered intravenously at a dose of 16 mg/kg weekly (cycles 1-2), on alternate weeks (cycles 3-6), and monthly thereafter. The median daratumumab monotherapy duration was 5.5 months (range, 0.2-28.7 months). The overall response rate was 45.2%, including 14 (33.3%) partial responses, 4 (9.5%) very good partial responses, and 1 (2.4%) complete response. The median duration of response was 4.9 months. The median progression-free survival (PFS) was 5.5 (95% confidence interval, 2.6-8.4 months) with 12- and 18-month PFS rates of 35.7% and 31.0%, respectively. The median overall survival was not reached; the 12- and 18-month overall survival rates were 64.3% and 59.5%, respectively. The depth of response had a significant effect on PFS (log-rank test, P = .026). Overall, of the 76 adverse events reported, 33 (43.4%) were grade ≥ 3; only 4 (9.52%) were grade 3 infusion-related reactions. No infusion-related reactions or adverse events led to treatment discontinuation. The present findings from our daratumumab early access program have confirmed the efficacy and safety profile of daratumumab monotherapy in heavily pretreated Turkish patients with RRMM. The present study investigated the efficacy and safety profile of daratumumab monotherapy in 42 patients with relapsed refractory multiple myeloma through a Turkish early access program. The current findings have confirmed the efficacy of daratumumab monotherapy in heavily pretreated patients with refractory multiple myeloma because of the deep and durable responses and favorable safety and tolerability profile.