The compound ABBV-155, which is a first-in-class antibody drug-conjugate comprising a BCL-XL inhibitor conjugated to an anti-B7H3 antibody, is now in clinical trials either as monotherapy or in combination with taxanes for the treatment of relapsed/refractory solid tumours including NSCLC, SCLC and breast cancer (NCT03595059). This evidence concerns the gene BCL2L1 and breast carcinoma.