Genome editing of immune checkpoints: CRISPR-mediated PD-1 inhibition in cancer
- Semin Oncol. 2026 Feb;53(1):152438. doi: 10.1016/j.seminoncol.2025.152438.
- 1. Electronic Marketing and Social Media, Economic and Administrative Sciences Zarqa University, Jordan; Research follower, INTI International University, Negeri Sembilan 71800, Malaysia. Electronic address: [email protected].
- 2. Biomedical Engineering Department, College of Engineering, Al-Mustaqbal University, Hillah, Babil 51001, Iraq. Electronic address: [email protected].
- 3. Faculty of Business and Communications, INTI International University, Negeri Sembilan 71800, Malaysia; Shinawatra University, 99 Moo 10, Bangtoey, Samkhok, Pathum Thani 12160, Thailand. Electronic address: [email protected].
- 4. Department of Chemistry and Biochemistry, School of Sciences, JAIN (Deemed to be University), Bangalore, Karnataka, India.
- 5. College of Applied Sciences, University of technology, Baghdad, Iraq.
- 6. Department of Medical Oncology, IMS and SUM Hospital, Siksha 'O' Anusandhan (Deemed to be University), Bhubaneswar, Odisha, India.
- 7. Department of Medical Analysis, Medical Laboratory Technique College, the Islamic University of Babylon, Babylon, Iraq.
- 8. University Institute of Pharma Sciences, Chandigarh University, Mohali, Punjab, India.
- 9. Department of Pharmaceutics, College of Pharmacy, University of Kut, Wasit, Iraq.
- 10. Department of CHEMISTRY, Sathyabama Institute of Science and Technology, Chennai, Tamil Nadu, India; Sharda School of Pharmacy, Sharda University, Greater Noida, India.
The programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint is a primary mechanism by which Tumors evade immune surveillance, limiting the efficacy of cytotoxic T lymphocytes (CTLs) and tumor-infiltrating lymphocytes (TILs). Although immune checkpoint blockade therapies have revolutionized Cancer treatment, their efficacy is restricted by acquired resistance, T-cell exhaustion, and tumor heterogeneity. The advent of CRISPR-Cas9 genome editing provides a precise and versatile approach to disrupt PD-1 or PD-L1, directly enhancing anti-tumor immune responses. Preclinical studies demonstrate that ex vivo PD-1 knockout in primary human T cells or TILs enhances proliferation, cytokine production, and cytotoxicity, resulting in improved tumor clearance in xenograft and humanized mouse models. In chimeric antigen receptor (CAR) T cell therapy, CRISPR-mediated disruption of PD-1 improves effector function, persistence, and resistance to exhaustion, with universal and allogeneic CAR-T platforms benefiting from multiplex genome editing. Direct PD-L1 knockout in tumor cells, often facilitated via nanoparticle- or biomaterial-assisted delivery, reshapes the immunosuppressive tumor microenvironment, promotes T cell infiltration, and enhances the efficacy of adoptive cellular therapy. Combination approaches integrating PD-1 editing with viral antigen targeting, long noncoding RNA (lncRNA) modulation, or conventional checkpoint blockade demonstrate synergistic anti-tumor effects. Clinically, early-phase trials in Non-Small Cell Lung Cancer, mesothelin-positive solid Tumors, and hematological malignancies establish the feasibility, safety, and preliminary efficacy of PD-1-deficient T cells. Despite these promising outcomes, challenges such as off-target effects, delivery efficiency, immunogenicity, long-term persistence, and regulatory considerations remain. This review aims to comprehensively evaluate preclinical and clinical studies investigating CRISPR-mediated PD-1/PD-L1 inhibition across various cancers, summarize mechanistic insights, and highlight translational opportunities and challenges for clinical implementation.