From antibodies to nanobodies: The next frontier in cancer theranostics for solid tumors

The field of cancer therapeutics has witnessed significant advancements over the past decades, particularly with the emergence of immunotherapy. This chapter traces the transformative journey from traditional antibody-based therapies to the innovative use of nanobodies in the treatment and diagnosis of solid tumors. Nanobodies are the smallest fragments of antibodies derived from camelid immunoglobulins and have redefined the possibilities in cancer theranostics due to their unique structural and functional properties. We provide an overview of the biochemical characteristics of nanobodies that make them particularly suitable for theranostic applications, such as their small size, high stability, enhanced infiltration into the complex tumor microenvironment (TME) and ability to bind with high affinity to epitopes that are inaccessible to conventional antibodies. Further, their ease of modification and functionalization has enabled the development of nanobody-based drug conjugates/toxins and radiolabeled compounds for precise imaging and targeted radiotherapy. We elucidate how nanobodies are being served as valuable tools for prognostic assessment, enabling clinicians to predict disease aggressiveness, monitor treatment response, and stratify patients for personalized therapeutic interventions.