Systematic elucidation and pharmacological targeting of tumor-infiltrating regulatory T cell master regulators.

Due to their immunosuppressive role, tumor-infiltrating regulatory T cells (TI-Tregs) represent attractive immuno-oncology targets. Analysis of TI vs. peripheral Tregs (P-Tregs) from 36 patients, across four malignancies, identified 17 candidate master regulators (MRs) as mechanistic determinants of TI-Treg transcriptional state. Pooled CRISPR-Cas9 screening in vivo, using a chimeric hematopoietic stem cell transplant model, confirmed the essentiality of eight MRs in TI-Treg recruitment and/or retention without affecting other T cell subtypes, and targeting one of the most significant MRs (Trps1) by CRISPR KO significantly reduced ectopic tumor growth. Analysis of drugs capable of inverting TI-Treg MR activity identified low-dose gemcitabine as the top prediction. Indeed, gemcitabine treatment inhibited tumor growth in immunocompetent but not immunocompromised allografts, increased anti-PD-1 efficacy, and depleted MR-expressing TI-Tregs in vivo. This study provides key insight into Treg signaling, specifically in the context of cancer, and a generalizable strategy to systematically elucidate and target MR proteins in immunosuppressive subpopulations.
Competing Interests: Declaration of interests C.G.D. is a co-inventor on patents licensed from JHU to BMS and Janssen; has served as a paid consultant to AZ Medimmune, BMS, Pfizer, Roche, Sanofi Aventis, Genentech, Merck, and Janssen; and has received sponsored research funding to his institution from BMS IioN and Janssen. A.C. is founder, equity holder, consultant, and director of DarwinHealth, Inc., which has licensed IP related to these algorithms from Columbia University. Columbia University is an equity holder in DarwinHealth, Inc. S.Y. has received sponsored research support to his institution from Celgene/BMS, Janssen, and Cepheid/Danaher and has served as a paid consultant to Cepheid/Danaher. A.O., C.A., C.G.D., and A.C. are co-inventors on US provisional patent no. 63/188,970, “Therapeutic modulation of regulatory T cells through master regulatory protein targeting,” which relates to the work described here.
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