...S killing of HMCL was modestly but statistically significantly correlated with MCL-1 expression but strongly correlated with both BCL-2 expression and the BCLxL:BCL-2, MCL-1:BCL-2 and BCLxL:MYC expression ratios...HMCL killing with S ranged from 0.9-91.6% (100nM) and 1.0-93.3% (500nM) with 70%, 80%, 37% and 61% demonstrating synergy when S was combined with V, A, B or P, respectively...1ºMM, cells were classified as sensitive when >20% cell death was induced and resistant with ≤20% cell death. The proportion of sensitive 1ºMM with single agent drug treatments was S100nM 37%, S500nM 66%...1ºMM demonstrated a statistically significant, albeit modest, correlation with the BCLxL:MCL-1 ratio...and the MCL-1:MYC ratio....The efficiency of MCL1i-induced killing of both HMCL and 1ºMM is modulated by the co-expression of pro-survival members of the BCL-2 family and MYC.