A Rational Design Strategy for Engineering CH4 Domain of IgE for Heterodimerization

The use of bispecific antibodies in cancer immunotherapy is a rapidly expanding domain. Growing relevance of diverse bispecific formats mediating multiple novel mechanisms of action is indicated by the approval of nine bispecific antibodies between 2021 and 2023. Likewise, interest is extending to explore different isotypes of monoclonal antibodies comprising IgA and IgE. Compared to IgG, IgE has been reported to elicit superior antitumour activity in ovarian carcinomas, melanomas, and breast carcinomas. Exploring other isotypes, such as IgE, in a bispecific format may enhance therapeutic applicability and efficacy in the case of solid tumors. However, studies investigating IgE antibodies in bispecific formats are limited due to missing technologies for heterodimerization with only one study providing a proof of concept for the development of bispecific IgE. Our study explored a computational approach for designing heterodimeric IgE antibodies on the basis of the conventional IgG knob-into-hole (KiH) strategy. Furthermore, the resulting novel variant of heterodimeric IgE retained target binding and Fc epsilon receptor engagement, thus providing a proof of concept for future development of therapeutic bispecific IgEs.