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. Cancer immunotherapy is a rapidly developing approach that uses the patient’s own immune system to recognize and destroy cancer cells. One of the most advanced forms of this treatment is chimeric antigen receptor (CAR) therapy, in which immune cells are genetically modified to better identify and attack tumors. However, current CAR therapies still face several challenges, including limited recognition of some cancer cells, treatment resistance, side effects, and difficulties in manufacturing. Nanobodies are very small antibody-like molecules that can be used as the cancer-recognizing part of CAR therapies. Compared with conventional antibody fragments, nanobodies are more compact, stable, and easier to modify, allowing scientists to design more flexible and potentially safer immune cell therapies. In this review, we discuss how nanobody-based CAR systems are being developed using different immune cells, including T cells, natural killer cells, gamma-delta T cells, and macrophages. Recent studies show that nanobody-based CAR therapies can improve cancer cell recognition, overcome tumor diversity, and support new treatment designs such as multi-target CARs, universal CAR platforms, and CAR cells that release additional immune-activating molecules. Early clinical studies have demonstrated promising activity in blood cancers such as leukemia and multiple myeloma. Although important challenges remain, including safety control, long-term effectiveness, and large-scale production, nanobody-based CAR therapies represent an exciting direction for future personalized cancer treatments. Continued research may help develop more adaptable and accessible immune-based therapies for patients with difficult-to-treat cancers.