P06.06 Enhancing trafficking and resistance to immunosuppression of synthetic agonistic receptor-transduced T cells in solid tumor models

Background Chimeric antigen receptor therapy – although very efficacious in B cell malignancies is facing many challenges which limit its success solid tumors, e.g. on-target off-tumor toxicities, heterogeneity, lack of T migration into tumors and an immunosuppressive tumor microenvironment. To better control effects address heterogeneity we developed a modular approach where equipped cells with synthetic agonistic (SAR). The SAR only activated the presence bispecific antibody (BiAb) cross-linking tumor-associated antigen. While could show efficacy platform different models, limited infiltration immune suppression still hamper function. We previously demonstrate that can be enhanced by transduction carefully chosen chemokine receptors like CXCR6, CCR4 CCR8. At same time, gene silencing checkpoint molecules PD-1 make more resistant to immunosuppression, thus assumed combining these approaches might generate desired product. Materials Methods All constructs had been generated overlap-extension cloning. EGFRvIII (E3) consists extracellular EGFRvIII, transmembrane CD28 intracellular CD3ζ. Human CXCR6-GFP, CCR4-GFP CCR8-GFP are composed fused GFP via 2A sequence. Primary human were retrovirally transduced stably express receptors. analyzed migration, cytotoxicity activation single double (E3 receptor) cells. In addition, was knocked out using CRISPR-Cas9 killing kinetics target assessed. Results Co-transduction significantly increased E3 their respective ligand while lysis target-expressing BiAb not affected vitro . Additionally knocking + CXCR6-GFP compared corresponding mock electroporated Conclusions Using controllable stopping dosing if adverse events occur. redirected alternative exchanging case escape. Here present add-ons this for resistance immunosuppression. Since upon co-transduction accelerated knockout two additional modifications seem promising options further improve vivo. Disclosure Information M. Schwerdtfeger: None. Benmebarek: F. Märkl: C.H. Karches: A. Employment (full or part-time); Significant; Daiichi Sankyo Deutschland GmbH. Öner: Geiger: Roche. B. Cadilha: S. Endres: V. Desiderio: C. Klein: Kobold: