MCL1 and Miyoshi myopathy: Therefore, further evaluation is necessary, both because of these early signs of cardiac toxicity with several Mcl-1 inhibitors in RRMM, as well as when combining Mcl-1 inhibition with Bcl-2 inhibition, and because of the potential for exacerbation of the known cardiovascular side effects of several anti-MM agents, such as proteasome inhibitors.