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

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 113; no. 4; pp. E459 - E468
• Main Authors: Rodgers, David T., Mazagova, Magdalena, Hampton, Eric N., Cao, Yu, Ramadoss, Nitya S., Hardy, Ian R., Schulman, Andrew, Du, Juanjuan, Wang, Feng, Singer, Oded, Ma, Jennifer, Nunez, Vanessa, Shen, Jiayin, Woods, Ashley K., Wright, Timothy M., Schultz, Peter G., Kim, Chan Hyuk, Young, Travis S.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 26.01.2016; National Acad Sciences
• Series: PNAS Plus
• Subjects: Animals; Antigens; Antigens, CD19 - immunology; Antigens, Neoplasm - immunology; Azides; B-Lymphocytes - immunology; B-Lymphocytes - pathology; Basic-Leucine Zipper Transcription Factors - immunology; Biological Sciences; Cancer; Cell Line, Tumor; Clinical trials; Cytokines; Cytokines - secretion; Cytotoxicity, Immunologic; Dose-Response Relationship, Immunologic; Female; Genes, Reporter; Genetic Vectors; Humans; Immunotherapy, Adoptive - adverse effects; Immunotherapy, Adoptive - methods; Leukemia, B-Cell - therapy; Lymphocyte Activation; Lymphopenia - etiology; Lymphopenia - prevention & control; Mice; Mice, Inbred C57BL; Mice, Inbred NOD; Mice, SCID; Phenylalanine - analogs & derivatives; PNAS Plus; Protein Engineering - methods; Receptors, Antigen, T-Cell - genetics; Receptors, Antigen, T-Cell - immunology; Recombinant Fusion Proteins - immunology; Saccharomyces cerevisiae Proteins - immunology; Sialic Acid Binding Ig-like Lectin 2 - immunology; Single-Chain Antibodies - genetics; Single-Chain Antibodies - immunology; Structure-Activity Relationship; T cell receptors; T-Cell Antigen Receptor Specificity; T-Lymphocyte Subsets - immunology; T-Lymphocyte Subsets - transplantation; Tumors; Xenograft Model Antitumor Assays; antibody engineering; leukemia; cancer; chimeric antigen receptor T cell; autologous cell therapy
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1524155113

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.