Researchers from the University of Ottawa have developed a functional screening technique for testing biological activity of bi-specific T-cell engager (BiTE) proteins using Jurkat T cells (a technique termed “BiTE-J”). Published in PLoS One, the authors used BiTE-J to identify EGFRvIII-CD3 engaging molecules and present this platform as a high-throughput, rapid, and cost-effective method for screening BiTEs. This approach allows researchers to quickly discover and optimize ideal BiTE candidates for further clinical development or integration into synthetic therapeutics.

BiTE antibodies are a class of immunomodulatory therapeutics that can induce strong antigen-targeted T cell responses. The development of BiTEs involves connecting two antigen-binding molecules (scFv) with a flexible linker, composed of a repeating amino acid sequence. This interaction between T cells and target cells triggers T cell activation and target cell killing. Unfortunately, optimizing BiTE-based therapies is time consuming and expensive. Thus, to broaden the application of BiTE therapeutics, there is a need for cost-effective high-throughput platforms for BiTE discovery and development. In this study, the authors sought to determine a high-throughput method for generating novel bi-specific antibody plasmids and rapidly producing BiTE proteins.

The initial modularized bispecific plasmid was developed using the amino acid sequence for blinatumomab, allowing either end of the BiTE DNA to be swapped for an alternative scFv in a single pot restriction ligation reaction. To test the plasmid, the authors used Jurkat T and HEK293T cells for transient BiTE production and activity. Efficient exchange of antigen-binding arms was demonstrated and multiple BiTE variants against different target cells, including EGFRvIII and CD19-positive cells were found. The results showed successful screening of novel BiTE molecules that induced T-cell activation and target cell killing, demonstrating the platform's flexibility and potential for discovering new therapeutic candidates. This method allows for rapid identification of promising BiTE candidates eliminates the need for antibody preparation, purification, or characterization. Overall, this study showcases the platform's potential for discovering new therapeutics, offering a cost-effective and accessible tool for the development of BiTE-based therapeutic agents.

Reference:

Shepherd A, Bennychen B, Marcil A, et al. A simplified function-first method for the discovery and optimization of bispecific immune engaging antibodies. PLoS One. 2023;18(6):e0273884. Published 2023 Jun 22. https://doi.org/10.1371/journal.pone.0273884

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