• David T Rodgers, Magdalena Mazagova, Eric N Hampton, Yu Cao, Nitya S Ramadoss, Ian R Hardy, Andrew Schulman, Juanjuan Du, Feng Wang, Oded Singer, Jennifer Ma, Vanessa Nunez, Jiayin Shen, Ashley K Woods, Timothy M Wright, Peter G Schultz, Chan Hyuk Kim, and Travis S Young.
• Department of Biology, California Institute for Biomedical Research, La Jolla, CA 92019;
• Proc. Natl. Acad. Sci. U.S.A. 2016 Jan 26; 113 (4): E459-68.

AbstractChimeric antigen receptor T (CAR-T) cell therapy has produced impressive results in clinical trials for B-cell malignancies. However, safety concerns related to the inability to control CAR-T cells once infused into the patient remain a significant challenge. Here we report the engineering of recombinant antibody-based bifunctional switches that consist of a tumor antigen-specific Fab molecule engrafted with a peptide neo-epitope, which is bound exclusively by a peptide-specific switchable CAR-T cell (sCAR-T). The switch redirects the activity of the bio-orthogonal sCAR-T cells through the selective formation of immunological synapses, in which the sCAR-T cell, switch, and target cell interact in a structurally defined and temporally controlled manner. Optimized switches specific for CD19 controlled the activity, tissue-homing, cytokine release, and phenotype of sCAR-T cells in a dose-titratable manner in a Nalm-6 xenograft rodent model of B-cell leukemia. The sCAR-T-cell dosing regimen could be tuned to provide efficacy comparable to the corresponding conventional CART-19, but with lower cytokine levels, thereby offering a method of mitigating cytokine release syndrome in clinical translation. Furthermore, we demonstrate that this methodology is readily adaptable to targeting CD20 on cancer cells using the same sCAR-T cell, suggesting that this approach may be broadly applicable to heterogeneous and resistant tumor populations, as well as other liquid and solid tumor antigens.

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