M-9140 (Merck KGaA) is an antibody-drug conjugate (ADC) that carries a DNA topoisomerase 1 (TOP1) inhibitor payload plus an antibody directed against carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5). CEACAM5 is a cell surface protein that is overexpressed in colorectal cancer and other solid tumors.