Immunotherapy and cell therapy have revolutionized the field of cancer treatment by harnessing the power of the immune system to fight cancer cells. However, the development of effective immunotherapy drugs such as immune checkpoint inhibitors requires extensive preclinical testing to ensure safety and efficacy. Breakthroughs in the field are faced with several challenges including the generation of appropriate humanized mouse models for preclinical evaluation. Among others, genetically-engineered mouse models have emerged as valuable tools for improving cancer treatment outcomes.