TCR engaging antigen-scaffolds for targeted expansion of functionally improved T cells for adoptive cell therapy

Abstract

Abstract Background Precise targeting of patient’s tumor can be facilitated through T cells recognizing specific pMHC complexes on these tumors. Once such antigen landscape is defined, an additional challenge relates to the ability to mount a functional T cell response specific to such antigens. Current T Cell expansion techniques provide no efficient strategy for antigen-specific stimulation and results largely in exhausted T cells. Here we present a new technology for ex-vivo peptide-MHC directed expansion and functional enhancement of T cells, using artificial antigen-presenting scaffolds (Ag-scaffolds). Methods Dextran backbone conjugated with streptavidin was used for Ag-scaffold assembly. Such backbone was incubated together with biotinylated MHC class I molecules holding a given peptide (pMHC) and biotinylated human cytokines in various ratios. PBMCs from healthy donors with known virus epitopes and from melanoma patients with known epitopes were expanded for 2 weeks with Ag-scaffold, added when the cell cultures were initiated and twice per week for two weeks. The expansion of antigen-specific CD8 T cells was monitored and analyzed by flow cytometry. Results Here we demonstrate the value of the antigen-scaffold based expansion, by the expansion of virus-CD8 T cells from peripheral blood, and tumor-specific T cells from both peripheral blood and tumor site. We can favorably expand both neo- and shared antigen specific T cell populations. The resulting T cell product exhibit a multifunctional cytokine profile upon antigen challenge, high levels of CD28 expression, and reduced levels of PD-1 expression. Importantly, numerous different pMHC-specific T-cell populations can be stimulated in a single culture, and we can obtain better tumor killing properties than conventional TIL-ACT products. Conclusion This study presents a new technology for expanding functionally enhanced antigen-specific CD8 T cells suited for implementation to ACT strategies. T cell phenotype and functionality are known to be important parameters in successful adoptive T cell transfer, and hence it´s plausible that antigen scaffold based expanded T cell product may improve treatment outcome compared to conventional expansion strategies. Legal entity responsible for the study The authors. Funding Innovation Fund Denmark. Disclosure All authors have declared no conflicts of interest.