Conducting chromium release [51Cr] assays with isolated CD8+ T cells, we found that miRNA-mediated silencing of EBAG9 in BCMA CAR T cells translated into more potent killing of BCMA+ MM (OPM-2) and B-NHL (DOHH-2, JeKo-1) target cell lines. Here, CD8A is linked to Miyoshi myopathy.