MCL1 and cardiomyopathy: While treatment with ABBV-467 achieved some disease control, it also caused elevated cardiac troponin levels in the plasma in some patients, prompting the study’s termination, despite the absence of other cardiac findings.371 The effect of MCL1 inhibitors on cardiomyocytes was also predicted by genetic studies showing cardiomyopathy and heart failure in cardiomyocyte-specific MCL1 knockout mice,372 indicating on-target toxicity of the MCL1 inhibitors.