Phase II trial of daratumumab with DCEP in relapsed/refractory multiple myeloma patients with extramedullary disease

Extramedullary multiple myeloma (EMD) is an aggressive subentity of multiple myeloma (MM) with poor prognosis. As more innovative therapeutic approaches are needed for the treatment of MM with EMD, we conducted this multicenter, non-randomized phase II trial of daratumumab in combination with dexamethasone, cyclophosphamide, etoposide and cisplatin (DARA-DCEP). A total of 32 patients (median age 59, range 35-73) were treated with DARA-DCEP. Based on the best response during the study, the complete remission (CR) rate was 35.5% and overall response rate (ORR) 67.7%. During the median follow-up of 11 months, the median progression-free survival (PFS) was 5 months and median overall survival (OS) 10 months. There were 7 long-term responders whose median PFS was not reached. The most common grade ≥ 3 hematologic AE was thrombocytopenia. The most common non-hematologic AE was nausea (22.6%), followed by dyspepsia, diarrhea and stomatitis (all 12.9%). Grade ≥ 3 daratumumab infusion-related reaction was noted in 9.7% of the patients. Except for the planned 30% dose adjustment in cycle 1, only 2 patients required DCEP dose reduction. This is one of the very few prospective trials focusing on EMD and we successfully laid grounds for implementing immunochemotherapy in MM treatment.