The Transgenic Mouse Human PD-1/L Model is the latest service offering to immuno-oncology researchers. This model could help speed the development of new cancer therapies by targeting a key checkpoint inhibitor of medicines already on the market that activates the immune system in fighting tumor cells. Animals or tumors expressing the human form of PD-1/L1 or CTLA-4 will allow for evaluation of the fully human-form of checkpoint inhibitors, either alone or in combination with other immune modulating agents, chemotherapeutics, oncolytic viruses, or radiation. The first of these models is ready to help speed the development of PD-1/L1 targeted therapeutics as single agents—or in combination with chemotherapeutics. The PD-1/L1 mouse is in the C57BL/6 strain with a double knock-in/out, replacing the murine PD-1 and PD-L1 with human genes. This model uses the syngeneic tumor MC38 expressing human PD-L1. The system was genotyped and expression of human PD-1 and PD-L1 verified by flow cytometry analysis.