Subcutaneous daratumumab in Chinese patients with relapsed or refractory multiple myeloma: an open-label, multicenter, phase 1 study (MMY1010).

Despite recent progress in multiple myeloma (MM) treatments, most patients will relapse and require additional treatment. Intravenous daratumumab, a human IgGκ monoclonal antibody targeting CD38, has shown good efficacy in the treatment of MM. A subcutaneous version of daratumumab was formulated to reduce the burden of intravenous infusions. We aimed to investigate the efficacy and safety of subcutaneous daratumumab in Chinese patients with relapsed/refractory MM based on the demonstrated noninferiority of subcutaneous daratumumab to intravenous daratumumab, with a shorter administration time and reduced infusion-related reaction rate in global studies. This phase 1, multicenter study (MMY1010; ClinicalTrials.gov Identifier: NCT04121260) evaluated subcutaneous daratumumab in Chinese patients with relapsed/refractory MM after 1 prior line (n = 1) or ≥2 prior lines (n = 20) of therapy, including a proteasome inhibitor and an immunomodulatory drug. Primary endpoints were pharmacokinetics and safety. Mean (standard deviation) maximum trough concentration of daratumumab was 826 (335) μg/mL, which was consistent with prior studies of subcutaneous daratumumab and intravenous daratumumab. Safety was consistent with safety profiles observed in other daratumumab studies, with no new safety concerns identified. Incidences of infusion-related reactions and injection-site reactions were low and consistent with other subcutaneous daratumumab studies. At a median follow-up of 7.5 months, the overall response rate was 57.1%, with a very good partial response or better rate of 38.1% and complete response or better rate of 19.0%. Our results demonstrate a favorable benefit/risk profile of subcutaneous daratumumab in Chinese patients with relapsed/refractory MM, potentially impacting clinical administration of daratumumab in this population.