TOP1 and neoplasm: Next, using an HCT116 colon tumor xenograft model, we compared the anti-tumor efficacy of m276-SL-PBD with that of DS-7300a, a CD276 ADC that recently entered clinical trials and employs a DNA topoisomerase I inhibitor payload.20 We also labeled the m276 antibody with the PBD drug linker tesirine, following the same method used for the clinically approved CD19-targeted loncastuximab tesirine ADC.