Daratumumab therapy for relapsed or refractory multiple myeloma: a single-center retrospective study.

Background: Significant advancements have been achieved in the quality of treatment for relapsed/refractory multiple myeloma (RRMM). Currently, daratumumab (DARA) is a highly effective drug widely used for RRMM; however, the knowledge on its efficacy and safety in Japanese patients remains limited. Accordingly, we aimed to evaluate the efficacy and safety of DARA therapy for RRMM.

Methods: We reviewed the medical records of patients who received DARA combination therapy and evaluated its efficacy and safety in our hospital.

Results: DARA was administered to 44 patients between October 2017 and March 2019. The median number of previous therapies was three (range 1-9). The rates of ≥ complete response and overall response were 27.3% and 61.4%, respectively. The median progression-free survival (PFS) duration was 12.3 months [95% confidence interval (CI) 5.1 to not reached (NR)] and estimated 2-year overall survival rate was 63.7% (95% CI 46.9-76.5%). In the multivariate analysis, patients with ≥ three previous lines of therapy and mass lesions showed significantly shorter PFS durations. The observed grade 3/4 adverse events (≥ 10%) included neutropenia (59.0%), thrombocytopenia (29.5%), anemia (36.4%), lymphopenia (38.6%) and febrile neutropenia (18.2%). None of the patients discontinued DARA therapy in spite of these AEs.

Conclusion: DARA is an effective treatment option for most patients and is tolerable. However, patients with heavy treatment before DARA therapy and mass lesions are likely to show poorer outcomes. Our findings suggest the use of DARA therapy early in the course of the disease.