Emerging CRISPR Approaches for Countering Immune Evasion: Insight from Recent Studies

Cancer immunotherapy has recently become an essential approach for treating cancer, showing considerable promise as a substitute for surgery, radiation therapy, and conventional chemotherapy. It primarily aims to boost the host’s natural defense system to combat cancer malignancies by utilizing components of immune checkpoint blockades (ICBs), mainly programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), along with elements of adoptive cellular therapies (ACTs) like Chimeric Antigen Receptor (CAR) therapy, T Cell Receptor (TCR) therapy and Tumor-Infiltrating Lymphocyte (TIL) therapy. However, cancer cells tend to undermine the effectiveness of cancer immunotherapeutic strategies by employing one or more immune evasion mechanisms. This review briefly highlights how key mechanisms of cancer immune evasion confer resistance to immunotherapy and how the Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 (CRISPR)/Cas9 systems, as gene-editing tools, are poised to enhance cancer immunotherapy for treating challenging cancers. We emphasize that CRISPR/Cas9 systems can be used to explore and positively alter the genes of the immune system, boosting the effectiveness of cancer immunotherapy by editing immune checkpoints, TILs, and CAR-T cells, and disrupting genes, facilitating tumors’ evasion of the immune system. Furthermore, we highlight the growing interest in emerging base editor technology to engineer natural killer (NK) cells to overcome NK-cell-based immunotherapy challenges, particularly human leukocyte antigens (HLA)-mediated limitations, and to engineer CAR-T cells for improved immunotherapy outcomes.