The regulation of MHC class I expression in HER2-positive cancer cells by T-DXd may depend on the cell type (e.g., CRC cells vs. GC cell lines, species differences [mice and human]) and methods of stimulation and analysis (e.g., T-DXd vs. DXd, treatment duration, and assay time, etc.). Here, ERBB2 is linked to colorectal carcinoma.