Nanobody CAR-T cells in cancer: From molecular design to clinical translation

Chimeric antigen receptor (CAR)-T cell therapy has revolutionized the management of hematologic malignancies. This review provides an overview of nanobody-based CAR-T therapy, highlighting how structural advancements in single-domain antibody (VHH) design enhance tumor targeting, safety, and manufacturability. Traditional CARs utilizing single-chain variable fragments (ScFv) continue to encounter numerous issues, including misfolding, tonic signaling, immunogenicity, and the difficulty in identifying certain tumor epitopes. Nanobody-based CARs employing VHHs constitute a compact, small, and highly selective alternative for tumor targeting. This review analyzes the molecular architecture, functional advantages, and clinical utilizations of nanobody CAR-T cells. We describe the structural features, including solubility, chemical resistance, and modularity that facilitate the advanced development of bispecific, trivalent, and logic-gated CAR forms. Preclinical studies demonstrate significant cytotoxicity of cells in vitro, elevated cytokine release, and successful in vivo tumor regression in both hematologic malignancies and solid tumors. Early-phase clinical trials, particularly targeting approaches based on BCMA (B cell maturation antigen), have presented encouraging safety profiles, persistence, and antitumor activity. Although there has been so much advancement, there are several limitations, such as the challenge of tumor heterogeneity, immune evasion, and T cell exhaustion. Innovative approaches, such as off-the-shelf allogeneic CARs, armored CARs, combination therapy based on checkpoint blockade or vaccines, and synthetic biology circuits, have the capabilities for overcoming several challenges listed above. Overall, nanobody CAR-T cells represent a flexible and innovative platform, which has a likelihood of increasing specificity, safety, and accessibility, thus paving the way for their wider integration in precision oncology beyond hematologic cancers.