1. FGFR4-Targeted Chimeric Antigen Receptors Combined with Anti-Myeloid Polypharmacy Effectively Treat Orthotopic Rhabdomyosarcoma.
- Author
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Sullivan PM, Kumar R, Li W, Hoglund V, Wang L, Zhang Y, Shi M, Beak D, Cheuk A, Jensen MC, Khan J, Dimitrov DS, and Orentas RJ
- Subjects
- Animals, Cell Line, Tumor, Humans, Immunotherapy, Adoptive, Mice, Polypharmacy, Receptor, Fibroblast Growth Factor, Type 4 genetics, Receptors, Antigen, T-Cell, Transforming Growth Factor beta, Tumor Microenvironment, Receptors, Chimeric Antigen genetics, Rhabdomyosarcoma drug therapy
- Abstract
Rhabdomyosarcoma (RMS) is the most common soft tissue cancer in children. Treatment outcomes, particularly for relapsed/refractory or metastatic disease, have not improved in decades. The current lack of novel therapies and low tumor mutational burden suggest that chimeric antigen receptor (CAR) T-cell therapy could be a promising approach to treating RMS. Previous work identified FGF receptor 4 (FGFR4, CD334) as being specifically upregulated in RMS, making it a candidate target for CAR T cells. We tested the feasibility of an FGFR4-targeted CAR for treating RMS using an NSG mouse with RH30 orthotopic (intramuscular) tumors. The first barrier we noted was that RMS tumors produce a collagen-rich stroma, replete with immunosuppressive myeloid cells, when T-cell therapy is initiated. This stromal response is not seen in tumor-only xenografts. When scFV-based binders were selected from phage display, CARs targeting FGFR4 were not effective until our screening approach was refined to identify binders to the membrane-proximal domain of FGFR4. Having improved the CAR, we devised a pharmacologic strategy to augment CAR T-cell activity by inhibiting the myeloid component of the T-cell-induced tumor stroma. The combined treatment of mice with anti-myeloid polypharmacy (targeting CSF1R, IDO1, iNOS, TGFbeta, PDL1, MIF, and myeloid misdifferentiation) allowed FGFR4 CAR T cells to successfully clear orthotopic RMS tumors, demonstrating that RMS tumors, even with very low copy-number targets, can be targeted by CAR T cells upon reversal of an immunosuppressive microenvironment., (©2022 The Authors; Published by the American Association for Cancer Research.)
- Published
- 2022
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