Nanobodies as next-generation antigen recognition domains for CAR-based cellular immunotherapies in cancer

Nanobody-based chimeric antigen receptors (CARs) represent a promising strategy for improving the specificity, modularity, and clinical adaptability of cellular immunotherapies. Replacing conventional single-chain variable fragments with camelid-derived variable heavy-chain domains (VHHs) may enhance receptor stability, antigen accessibility, and construct design. This review summarizes nanobody-based CAR applications across T cells, natural killer (NK) cells, γδ T cells, and macrophages, drawing on literature published between 2011 and 2026 and identified through PubMed/MEDLINE, Scopus, Web of Science, and Google Scholar. Nanobody-based CAR-T cells support recognition of hematologic and solid tumors and facilitate dual targeting, tandem receptors, affinity tuning, and immune-modulating designs. CAR-NK cells combine antigen-directed activity with innate cytotoxicity and potential advantages for allogeneic, off-the-shelf treatment. CAR-γδ T cells integrate innate-like surveillance with engineered specificity and may offer reduced graft-versus-host disease risk. CAR-macrophages exploit phagocytosis and tumor microenvironment remodeling to promote antitumor responses. Emerging universal, switchable, -generated, and synthetic antigen-based CAR platforms further highlight the versatility of nanobodies for controllable and scalable therapies. Collectively, these approaches offer opportunities to address tumor heterogeneity, antigen escape, and treatment safety, although further preclinical optimization and rigorous clinical evaluation are needed to establish their efficacy, persistence, and long-term safety in diverse patient populations and clinical settings.