YM155 (sepantronium bromide) was introduced as a transcriptional suppressor of survivin expression that displayed activity against a broad range of cancer types in preclinical models.1, 3 However, further studies suggested that the YM155-induced inhibition of survivin expression may be a secondary effect downstream of YM155-induced DNA damage1, 4, 5 or associated with Myeloid Cell Leukemia 1 (Mcl-1) depletion.6 This evidence concerns the gene MCL1 and cancer.