Towards Effective Immunotherapy of Multiple Myeloma: Enhanced Elimination of Myeloma Cells by Combination of Lenalidomide with the Human CD38 Monoclonal Antibody Daratumumab

Abstract 3059

Since its approval by the FDA, lenalidomide (LEN) demonstrates impressive results in patients with newly-diagnosed and relapsed multiple myeloma (MM). Despite these improvements, MM remains incurable, and new innovative treatments need to be developed in efforts to improve long term outcomes. Recently we have developed a new human CD38 antibody, daratumumab (DARA) which mediates MM cell killing via complement dependent cytotoxicity (CDC), antibody dependent cellular cytotoxicity (ADCC) and apoptosis. In the current study we evaluated the potential benefits of combining lenalidomide (LEN) with daratumumab (DARA). We demonstrate that DARA-dependent ADCC of purified primary MM cells, as well as of CD38⁺ UM 9 MM cells was significantly augmented by pre-treatment of PBMC effector cells with LEN. Importantly, a synergism between LEN and DARA was observed in ex-vivo assays, which allowed us to investigate ADCC directly in whole BM-MNC, thus without isolating MM cells from their natural environment. Interestingly, DARA-induced ADCC was significantly upregulated in PBMC derived from three MM patients who were undergoing LEN treatment. In conclusion, these results support the hypothesis that powerful and complementary effects may be achieved by combining LEN and DARA in clinical MM management.