Recent advances of CRISPR screen in cancer immunology

Cancer has become a major global health concern due to its high incidence and mortality. Despite continuous progress in diagnosis and treatment, effective long-term management of cancer remains challenging for many patients. One of the major reasons for this is the intrinsic complexity of tumors, which includes extensive heterogeneity among cancer cells, the emergence of drug resistance, and the capability of tumor cells to escape immune surveillance through diverse molecular mechanisms. Conventional treatments such as surgical resection, radiotherapy, and chemotherapy have indeed prolonged survival in numerous cases, but they are often associated with considerable toxicity, limited specificity, and a lack of durable responses. Moreover, these approaches frequently lead to tumor recurrence and metastasis, especially in advanced-stage patients. In recent years, immunotherapy has emerged as a revolutionary approach in oncology. By leveraging patients’ own immune system to recognize and eliminate cancer cells, immunotherapy offers advantages that conventional treatments lack—namely, high specificity, adaptability, and the potential for long-term immune memory. Over the past decade, therapies such as immune checkpoint therapy (ICT) and adoptive cell therapy (ACT) have led to remarkable clinical success in various cancers, including melanoma, non-small cell lung cancer (NSCLC), renal cell carcinoma, and hematologic malignancies such as acute lymphoblastic leukemia, follicular lymphoma, and mantle cell lymphoma. Some patients have even achieved complete and long-lasting remission. Nevertheless, the response to immunotherapy varies widely among individuals, and many patients still fail to respond initially or develop resistance over time. This has highlighted the urgent need to identify more effective, broadly applicable, and safer therapeutic targets. CRISPR screen has become a powerful tool in the field of cancer research and immunotherapy. Based on the CRISPR/Cas system, this technology allows for precise, high-throughput genome editing to investigate gene function. Genome-wide CRISPR knockout, CRISPRa, or CRISPRi screen can be applied in both immune cells and tumor cells to identify genes that affect critical biological processes. CRISPR screens in immune cells can uncover key regulators of cell proliferation, activation, differentiation, migration, and cytotoxic functions—factors that are essential for mounting robust antitumor immune responses. Modifying such genes can enhance the efficacy and help overcome dysfunctional exhaustion or immunosuppression of immune cells in the tumor microenvironment. CRISPR screens in tumor cells have been used to identify genes involved in immune evasion, resistance to immune cell killing, promotion of cell proliferation, and metastasis. These screens are particularly valuable for discovering molecular pathways that contribute to resistance in patients who do not respond to existing immunotherapies and await new immunotherapies. Here, we review recent advances in CRISPR screen technology and its diverse applications in immuno-oncology. We summarize the integration of CRISPR screen with advanced technologies such as single-cell RNA sequencing, epigenomic profiling, and proteomics, which allows for more precise target identification and mechanistic insights. We highlight how CRISPR screens in both immune and tumor cells have helped identify critical regulatory networks involved in tumor progression, metastasis, immune evasion, and therapy resistance. These findings may lay the solid foundation for the development of next-generation immunotherapies aimed at improving treatment response, broadening patient coverage, and achieving long-term remission.