Once monthly elotuzumab, lenalidomide plus dexamethasone for multiple myeloma; a multicenter observation study

Introduction: Elotuzumab, lenalidomide plus dexamethasone (ERd) is a standard salvage chemotherapy for multiple myeloma, and elotuzumab is commonly administered every 2 weeks after cycle 3 (conventional ERd). Alternatively, elotuzumab may often be used every four weeks (monthly ERd) in real-world practice. The purpose of this multicenter observational study was to investigate the efficacy and tolerability of monthly ERd
Methods: We investigated the efficacy and tolerability between conventional and monthly ERd regimens for the myeloma patients in six institutes retrospectively. 
Results: Seventy-five patients were included in this study. The median patient age was 68 years. The median number of prior chemotherapies was two (1-5). The number of patients with prior lenalidomide exposure was 57 (76.0%). The number of progressive disease (PD) and non-PD before ERd were 23 (30.7%) and 52 (69.3%), respectively. The frequency of PD before ERd was significantly lower in the monthly ERd group than in the conventional ERd group. In 26.9 months of median follow-up period, the 2-year progression-free survival (PFS) rate in the monthly ERd group was significantly longer than that in the conventional ERd group (95.0% and 62.0%, hazard ratio 0.082, P = 0.002). However, no significant difference of PFS in these two ERd groups was found using multivariate analysis. The complete response rates were similar between the monthly and conventional ERd groups (55.0% and 32.7%, P = 0.109). There was no significant difference in the incidence of adverse events between the monthly and conventional ERd groups (35.0% and 54.5%, P = 0.192). There was no significant difference in the kinetics of the mean absolute lymphocyte count, CD4, CD8, CD16, CD56, and CD57 positive lymphocyte counts, and CD4 to CD8 ratio between the monthly and conventional ERd groups. 
Discussion/conclusion: The efficacy and tolerability of monthly ERd were similar to those of conventional ERd. Thus, monthly ERd might be a reasonable option, considering the quality of life of patients and convenience.