Kawther Zaher, Jehan Alrahimi
Background: Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of select hematologic malignancies and is increasingly being explored for non-oncological indications, including autoimmune diseases and persistent infectious diseases. This systematic review synthesized current evidence on CAR T cell and CAR-Treg approaches beyond oncology, with emphasis on therapeutic targets, translational and clinical outcomes, safety, and implementation barriers. Methods: The review followed PRISMA 2020 guidelines. PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, ClinicalTrials.gov, and major trial registries were searched for studies published from 1 January 2010 to 31 March 2026. Eligible studies included clinical, preclinical, and translational investigations of CAR T cell or CAR-Treg strategies in autoimmune or infectious diseases. Results: Because of heterogeneity in disease indications, CAR constructs, endpoints, and study designs, findings were synthesized descriptively. The strongest early clinical signals were observed with B cell-directed CAR T cell therapy for severe, refractory autoimmune diseases, particularly systemic lupus erythematosus, systemic sclerosis, and inflammatory myopathies. Infectious disease applications, mainly HIV and hepatitis B, showed preliminary safety, persistence, and partial antiviral activity, but durable pathogen eradication remains unproven. Conclusion: Overall, CAR T cell therapy beyond oncology is promising but remains preliminary, requiring standardized reporting, long-term safety monitoring, scalable manufacturing, and carefully defined risk-benefit thresholds. Human clinical evidence was interpreted separately from preclinical and mechanistic evidence, and clinical conclusions were based primarily on human studies.