CD274 and neoplasm: We next evaluated the antitumor efficacy of AP-diABZI in mice inoculated with parental or PD-L1 knockout EMT6 cells and found that it was less effective (100% vs. 60% CR rate) when PD-L1 was not expressed by breast cancer cells (Fig. 5g,h, Fig. S24), potentially due to decreased tumor accumulation and/or reduced checkpoint inhibition.