MCL1 and neoplasm: In this context, other BH3 mimetics such as ABT-737 and its oral derivative navitoclax, which bind to Bcl-2, Bcl-xL and Bcl-w (but not Mcl-1) with high affinity have also been investigated in MM, but their development was precluded either due to lack of anti-tumor activity or unacceptable toxicity [37].