Bispecific nanobodies - promising engineered candidates with high therapeutic efficiency

Bispecific nanobodies are the emerging class of engineered nanobodies with great scope for targeted therapy due to their small size, high stability, extended half-life, and dual antigenic recognition properties. They can bind to two different antigens simultaneously which significantly improves the therapeutic index in the treatment of various diseases. To achieve enhanced binding avidity, specificity and minimal off-target effects, the bispecific nanobodies have been further subjected to advanced engineering strategies such as site-specific combinations, fusions and multivalent formats. The recombinant production of bispecific nanobodies has been tested in bacterial, yeast and mammalian expression platforms to facilitate their large-scale production and cost-effective clinical applications. This review exclusively focuses on recent progress in the design and development of bispecific nanobodies. It presents the engineering of nanobodies into bispecific formats, their design, expression strategies and therapeutic outcomes. It also discusses the recent preclinical and clinical developments of bispecific nanobodies focusing on tackling half-life extension problems, reducing immunogenicity and optimal delivery modalities. Overall, with the promising scope of bispecific nanobodies as targeted therapies, their acceptance into mainstream medicine holds great promise for precision and personalized therapeutic approaches for the effective treatment of various infections, cancers, autoimmune and neurodegenerative diseases.