Medigene AG presents superior recombinant T cell receptor (rTCR) engineered T cell functionality as well as a favorable safety profile when rTCR-T cells are armored and enhanced with the PD1-41BB costimulatory switch protein (CSP) at the American Association for Cancer Research (AACR) Annual Meeting 2024 taking place April 5-10, 2024, in San Diego, USA. The data presented in the poster demonstrated that the CSP-mediated costimulatory signal is TCR-gated, such that costimulation only takes place when a specific peptide-human leukocyte antigen (pHLA) complex is present on a tumor cell and triggers a signal through the rTCR expressed by the TCR-T cells. Enhanced, gated T cell functionality of CSP-armored rTCR-T cells increased secretion of interferon-?

(IFN?) only when tumor cells simultaneously expressed the pHLA target antigen and PD-L1. In addition, CSP-armored rTCR-T cells showed high sensitivity in recognition of diverse tumor cell lines of different tissue origin, such as melanoma, sarcoma, and gastric cancer which varied in levels of pHLA and PD-L1 in vitro. Rapid and sustained killing of 3D tumor cell-derived spheroids only occurred when PD-L1-positive tumor cells simultaneously expressed the specific pHLA target antigen.

Importantly, no recognition of healthy cells occurred if they lacked the pHLA target antigen, irrespective of PD-L1 expression, underpinning the safety of combining the CSP with a rTCR to generate rTCR-T cells that displayed no signs of toxicity for diverse healthy tissues in vitro.