Neil Koby Reid

Introduction. Chimeric Antigen Receptor (CAR) T-cell therapy is one branch of immunotherapy that is successful in treating refractory hematological malignancies^1,2. Current CAR immune cells are host-specific cells that express transmembrane proteins that activate intrinsic immune cell pathways without the traditional MHC presentation. Newer generations of CAR therapies improve upon the precision, safety, and versatility of existing treatments. Antigen escape, immunosuppressive tumor microenvironments, and clinical & finical toxicity are some of the biggest obstacles being investigated today^2–6. As the collaborative efforts between physicians, engineers and scientists continue to grow, novel solutions are being developed that integrate concepts like logical circuits and synthetic biology into new, living immunotherapies. Methods. SUPRA CARs utilize a modular design including signaling and co-stimulatory domains like CD3z, CD28, 41BB, and many others on CD4+, CD8+, Treg, and NK immune cells^7,8. The CAR immune cells were validated on HER2+ K562 cells in vitro by measuring the release of cytokines cd69 and IFN-y. Following this, tumor clearance was followed in immunocompromised mice after the introduction of SK-BR-3 breast cancer cells and Jurkat T cancer cells as xenograft tumor models. Alternative CAR T cell designs were created targeting GPC2 fetal antigen to investigate the low antigen thresholds that are common in tumor microenvironments around solid tumors⁹. Lastly, the management of Cytokine Release Syndrome was investigated with patients on an FDA-approved CAR T cell therapy utilizing the IL-6R antibody tocilizumab to compare with upcoming generations of CAR immune cells that contain emergency abort features^7,10,11. Results. The introduction of the logical operations of AND gates in CD8+ T cells and NOT gates in NK cells produced more specific targeting of tumors by modulating zipFv concentrations⁸. Additionally a three-input (A AND B) AND NOT C logic showed synergistic trends in IFN-y production that contributed to improved on-target specificity when compared with non-integrated CAR receptors. The tunability of split CARs increased safety demonstrated by controlled and predictable titrations of extracellular fragments⁷. Importantly many CAR designs incorporate mechanisms for a sudden reversal of cytokine release syndrome that behaves similarly to tocilizumab¹¹. Discussion. There is a plethora of new research around CAR cell therapy addressing many different obstacles being encountered with existing CAR immune therapies. Incorporating logical circuits and split designs pave the way for a new generation of tunable, safer, and more specific immunotherapies; however, more investigation is needed into the single-cell and clinical applications of these newer generations of CAR immune cells.

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