PDCD1 and neoplasm: To dissect the cellular and molecular mechanism by which targeted desialylation augments anticancer immune responses, we injected mice bearing palpable subcutaneous B16D5-HER2 tumors intraperitoneally with two doses of either E-301 or E-301 LOF alone or in combination with PD-1– and CTLA-4–blocking antibodies and performed single-cell RNA sequencing (scRNA-seq) on CD45+ tumor-infiltrating immune cells 7 days after the first treatment (Fig. 4A).