Results of the Daratumumab Monotherapy Early Access Treatment Protocol in Patients from Brazil with Relapsed or Refractory Multiple Myeloma

Introduction: Daratumumab is a CD38-targeting monoclonal antibody with established efficacy and safety in patients with relapsed or refractory multiple myeloma (RRMM). We report results of an early access protocol (EAP) of daratumumab monotherapy for RRMM in a cohort of Brazilian patients.

Methods: Patients with RRMM and ≥3 prior lines of therapy, including a proteasome inhibitor (PI) and an immunomodulatory drug (IMiD), or who were double refractory to both a PI and IMiD received daratumumab, 16 mg/kg, intravenously weekly for 8 weeks, biweekly for 16 weeks, and every 4 weeks thereafter until disease progression, unacceptable toxicity, loss of clinical benefit, or study conclusion or if daratumumab became available with reimbursement.

Results: Forty-nine patients received ≥1 dose of daratumumab. The median (range) duration of treatment was 6.4 (0.3-11.8) months, with a median (range) of 8 (1-13) treatment cycles. Grade 3/4 treatment-emergent adverse events (TEAEs) were reported in 38.8% of patients, most frequently neutropenia and pneumonia (10.2% each). Seven (14.3%) patients discontinued treatment due to TEAEs; 3 patients discontinued due to daratumumab-related TEAEs. Serious TEAEs occurred in 38.8% of patients. Infusion-related reactions were reported in 25 (51.0%) patients, were primarily grade 1/2, and the majority (23 patients) occurred during the first infusion. Twenty (40.8%) patients achieved a partial response or better; median progression-free survival was 8.25 (95% confidence interval, 5.55-17.54) months.

Conclusion: In this EAP, daratumumab monotherapy in Brazilian patients showed a safety and efficacy profile consistent with clinical studies of daratumumab monotherapy in patients with heavily pretreated RRMM.