Radioligand-Antibody Conjugates: Integrating Antibody Engineering, Chelator Chemistry, and Radioligands for Precision Theranosis.

Radioligand-antibody conjugates (RadioBodies), also known as radiolabeled antibodies, represent an emerging class that enables targeted delivery of radionuclides to tumor cells using antibodies. Conventional antibodies (full-length antibodies) and nonconventional antibodies (antibody fragments) are ideal agents for targeted delivery of radionuclides to tumor sites, owing to their high affinity and specificity. Antibody guides the radionuclide to a precise target, where it participates in killing of cancer cells (therapy) or helps with imaging (diagnosis). RadioBodies are yet to be effectively employed in cancer theranostics but have the potential for the same. Conventional antibodies have long circulatory half-lives, a feature that limits their application in diagnosis but is desirable for therapy. Using nonconventional antibodies (antibody fragments) offers the advantages of small size and removal of the Fc function, which reduces the serum half-life. In recent years, advances in antibody engineering, chelator chemistry and radionuclide technology have greatly facilitated the development of RadioBodies for desired applications. In this review, we discuss the roles of antibodies, chelators, and radionuclides in the clinical development of RadioBodies for cancer theranostics.