Diabodies: molecular engineering and therapeutic applications.

Bispecific antibodies are capable of interacting with two different antigens and when selected properly, can redirect cytotoxic effector cells to tumor cells for effective killing. These antibodies are therefore of great interest in the research and development of cancer treatment. Over the last two decades, many different bispecific antibody-derived molecular formats have been described, among which diabodies represent an important class of engineered molecules that possess tumor-targeting function. Since diabodies were first introduced in the early 1990s, extensive efforts have been made to optimize their physicochemical and key functional properties, as well as to provide in vivo proof of concept of their antitumor efficacy in animal models. With the clinical validation of the T-cell-retargeting mechanism for cancer therapy currently in place, there is renewed interest in this bispecific class of biologic molecules, with additional novel formats being described in recent years. Even with the remaining challenges of the manufacturing yields and drug-like properties, diabodies and their derivatives remain viable therapeutic modalities that warrant further consideration and development.