biostudies-literatureUnknown15(1)Inoue HThe advent of immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway has revolutionized cancer treatment, resulting in improved clinical outcomes. However, resistance remains a critical challenge. This study aimed to comparatively elucidate immunophenotypic changes in syngeneic mouse models sensitive (MC-38) or resistant (LLC1) to anti-PD-1 monoclonal antibody (mAb) treatment. In the sensitive MC-38 model, anti-PD-1 therapy increased dendritic cells (DCs) and macrophages, while decreasing myeloid-derived suppressor cells (MDSCs) within the tumor microenvironment. Enhanced expression of antigen presentation molecules (MHC I/II) and costimulatory molecules (CD80/CD86) was observed on tumor-associated DCs and macrophages. Tumor-infiltrating CD4⁺T, CD8⁺T, regulatorScientific reports8311https://www.ebi.ac.uk/biostudies/studies/S-EPMC11894063biostudies-literatureComprehensive immunophenotyping reveals distinct tumor microenvironment alterations in anti-PD-1 sensitive and resistant syngeneic mouse model.PMC11894063Ebi NFujita MHamasaki TNakao AMinomo HInoue KNagata IInoue HHorai NfalseComprehensive immunophenotyping reveals distinct tumor microenvironment alterations in anti-PD-1 sensitive and resistant syngeneic mouse model.The advent of immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway has revolutionized cancer treatment, resulting in improved clinical outcomes. However, resistance remains a critical challenge. This study aimed to comparatively elucidate immunophenotypic changes in syngeneic mouse models sensitive (MC-38) or resistant (LLC1) to anti-PD-1 monoclonal antibody (mAb) treatment. In the sensitive MC-38 model, anti-PD-1 therapy increased dendritic cells (DCs) and macrophages, while decreasing myeloid-derived suppressor cells (MDSCs) within the tumor microenvironment. Enhanced expression of antigen presentation molecules (MHC I/II) and costimulatory molecules (CD80/CD86) was observed on tumor-associated DCs and macrophages. Tumor-infiltrating CD4⁺T, CD8⁺T, regulator2025-01-01T00:00:00Z2025 Mar2025-04-04T20:26:00.244Z2025-04-04T20:26:00.244ZS-EPMC118940634006491510.1038/s41598-025-91979-w