Single-agent daratumumab in very advanced relapsed and refractory multiple myeloma patients: a real-life single-center retrospective study

The anti-CD38 monoclonal antibody daratumumab is approved as a single agent for the treatment of patients with relapsed and refractory multiple myeloma (RRMM) who have received at least three prior lines of therapy, including a proteasome inhibitor (PI) and an immunomodulatory agent (IMID), or who are double refractory to a PI and an IMID. To date, no real-life data on the efficacy and tolerance of daratumumab in this setting are available. We report here the results of a single-center series of 41 RRMM patients treated with single-agent daratumumab outside clinical trials. Patients received a median number of 4 prior therapies. All patients were previously exposed to PI and IMID and all patients were refractory to the last line of therapy. Most patients presented with high-risk characteristics, including 24% adverse cytogenetics (del17p/t(4,14)), 31% extramedullary disease and 12% circulating plasmacytosis at time of daratumumab therapy. The overall response rate was 24%, including 5% very good partial response or better. After a median follow-up of 6.5 months, all patients experienced disease relapse. The median progression-free survival was 1.9 months. At the time of disease progression, 44% of patients did not receive subsequent therapy. The median overall survival was 6.5 months. No new safety signal was identified. These real-life results revealed modest efficacy of single-agent daratumumab in advanced patients with RRMM in comparison with data from clinical trials.