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Proc Natl Acad Sci U S A. 2016 Jan 26;113(4):E459-68. doi: 10.1073/pnas.1524155113. Epub 2016 Jan 12.

Switch-mediated activation and retargeting of CAR-T cells for B-cell malignancies.

Author information

1
Department of Biology, California Institute for Biomedical Research, La Jolla, CA 92019;
2
Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037.
3
Department of Biology, California Institute for Biomedical Research, La Jolla, CA 92019; Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037 schultz@scripps.edu chkim@calibr.org tyoung@calibr.org.
4
Department of Biology, California Institute for Biomedical Research, La Jolla, CA 92019; schultz@scripps.edu chkim@calibr.org tyoung@calibr.org.

Abstract

Chimeric 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.

KEYWORDS:

antibody engineering; autologous cell therapy; cancer; chimeric antigen receptor T cell; leukemia

PMID:
26759369
PMCID:
PMC4743815
DOI:
10.1073/pnas.1524155113
[Indexed for MEDLINE]
Free PMC Article

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