To test if sensitivity could be detected in other B cell malignancies, we performed drug testing on cell line models of CLL (n=4), multiple myeloma (MM) (n=8) and mantle cell lymphoma (MCL) (n=7)....We found that high expression of the anti-apoptotic proteins myeloid cell leukemia-1 (Mcl-1) or B-cell lymphoma-extra large (Bcl-xL) predicted low sensitivity to trametinib + venetoclax.