Safety and efficacy of daratumumab in Chinese patients with relapsed or refractory multiple myeloma: a phase 1, dose-escalation study (MMY1003)

Daratumumab monotherapy demonstrated favorable safety and efficacy in relapsed/refractory multiple myeloma (RRMM) patients in the global phase 1/2 GEN501 and phase 2 SIRIUS studies. MMY1003 evaluated daratumumab monotherapy specifically in Chinese patients with RRMM. This 3-part, open-label, phase 1, dose-escalation study included patients with ≥ 2 prior lines of therapy. Part 3 included patients who had received a proteasome inhibitor (PI) and immunomodulatory drug (IMiD) and experienced disease progression on their last regimen. Patients received intravenous daratumumab 8 mg/kg or 16 mg/kg in part 1 and 16 mg/kg in parts 2 + 3. Primary endpoints were dose-limiting toxicity (DLT; part 1), pharmacokinetics (parts 1 + 2), and adverse events (AEs). Fifty patients enrolled. The first 3 patients in part 1 received daratumumab 8 mg/kg; remaining patients in parts 1–3 received daratumumab 16 mg/kg. In the daratumumab 16 mg/kg group (n = 47), patients received a median of 4 prior lines of therapy; 32% were refractory to a PI and IMiD, and 79% were refractory to their last prior therapy. No DLTs occurred. Thirty-six (77%) patients reported grade 3/4 treatment-emergent AEs. Thirteen (28%) patients experienced infusion-related reactions. At an 18.5-month median follow-up, overall response rate was 43%. Median progression-free survival (PFS) and overall survival (OS) were 6.7 months and not reached, respectively; 12-month PFS and OS rates were 35% and 70%. Pharmacokinetic results (n = 22) were consistent with other studies. Safety, pharmacokinetics, and efficacy of daratumumab monotherapy were confirmed in Chinese patients with RRMM. This trial is registered on ClinicalTrials.gov (NCT02852837).