Engineered SH3-Derived Sherpabodies Function as a Modular Platform for Targeted T-cell Immunotherapy

Engineered T-cell therapies have emerged as a promising approach for cancer treatment, yet their application to solid tumors remains challenging because of the limited specificity and persistence of current antigen recognition strategies. In this study, we introduce sherpabodies, engineered from a human SH3 domain scaffold, as a class of antibody-mimetic proteins capable of precise tumor-associated antigen (TAA) recognition. A phage display library identified sherpabodies against a panel of popular TAAs, which were subsequently incorporated into second-generation chimeric antigen receptor (CAR) constructs that were termed sherpabody-guided CARs (SbCAR). These SbCARs demonstrated potent in vitro specificity and cytotoxicity against solid cancer TAAs, without cross-reactivity to closely related proteins. The modularity, versatility, and small size of sherpabodies enabled generation of multispecific SbCARs, in particular trispecific SbCARs with OR logic that could robustly activate with cells expressing any or combinations of three cognate TAA targets, as well as circuits with IF-THEN logic in combination with synthetic Notch. In vivo, SbCAR T cells elicited a dose-dependent antitumor response in xenograft mouse models, highlighting their potential for therapeutic application. Furthermore, an inducible SbCAR system displayed enhanced persistence and antitumor activity when compared with constitutive CARs. These findings suggest that sherpabodies represent a versatile and promising platform for the next generation of CAR T-cell therapies, particularly for solid tumors. Significance: Sherpabodies represent a biological targeting technology that could help extend the success of CAR T-cell therapy from treating leukemias and lymphomas to the treatment of solid cancers.