Tumoral micro-environment in malignant haematological diseases, notably in multiple myeloma, is active on plasma cells survival and proliferation. Monocytosis and monocytes typing are described in multiple myeloma response as factors on proliferation and cell death evasion. CART cells have improved multiple myeloma care in last 5 years, nethertheless, early relapse occur and we must identify predictor factors of better response. The aim of this study is to analyze basic level and phenotyping of monocytes before and after CART cells infusion and study their impact on multiple myeloma response