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ORIGINAL RESEARCH article

Front. Immunol.
Sec. Cancer Immunity and Immunotherapy
Volume 15 - 2024 | doi: 10.3389/fimmu.2024.1426657
This article is part of the Research Topic Community Series in The Immunosuppressive Tumor Microenvironment and Strategies to Revert its Immune Regulatory Milieu for Cancer Immunotherapy: Volume II View all articles

Antisense targeting of FOXP3+ Tregs to boost anti-tumor immunity

Provisionally accepted
Tatiana Akimova Tatiana Akimova 1,2,3Liqing Wang Liqing Wang 1,2Zhanna Bartosh Zhanna Bartosh 2,3Lanette M. Christensen Lanette M. Christensen 2Evgeniy Eruslanov Evgeniy Eruslanov 1Sunil Singhal Sunil Singhal 1Veenu Aishwarya Veenu Aishwarya 3Wayne Hancock Wayne Hancock 1,2*
  • 1 University of Pennsylvania, Philadelphia, United States
  • 2 Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States
  • 3 AUM LifeTech, Inc., Philadelphia, United States

The final, formatted version of the article will be published soon.

    Our goal is to improve the outcomes of cancer immunotherapy by targeting FOXP3+ T-regulatory (Treg) cells with a next generation of antisense oligonucleotides (ASO), termed FOXP3 AUMsilence ASO. We performed in vitro experiments with human healthy donor PBMC and clinical samples from patients with lung cancer, mesothelioma and melanoma, and tested our approach in vivo using ASO FOXP3 in syngeneic murine cancer models and in humanized mice. ASO FOXP3 had no effects on cell viability or cell division, did not affect expression of other FOXP members, but decreased expression of FOXP3 mRNA in PBMC by 54.9% and in cancer samples by 64.7%, with corresponding 41.0% (PBMC) and 60.0% (cancer) decreases of Treg numbers (all p<0.0001). Hence, intratumoral Treg were more sensitive to the effects of ASO FOXP3 than peripheral blood Tregs. Isolated human Treg, incubated with ASO FOXP3 for 3.5 hours, had significantly impaired suppressive function (66.4%) versus Scramble control. In murine studies, we observed a significant inhibition of tumor growth, while 13.6% (MC38) to 22% (TC1) of tumors were completely resorbed, in conjunction with ~50% decrease of Foxp3 mRNA by qPCR and decreased numbers of intratumoral Tregs. In addition, there were no changes in FOXP3 mRNA expression or in the numbers of Tregs in draining lymph nodes and in spleens of tumor bearing mice, confirming that intratumoral Treg had enhanced sensitivity to ASO FOXP3 in vivo compared to other Treg populations. ASO FOXP3 Treg targeting in vivo and in vitro was accompanied by significant downregulation of multiple exhaustion markers, and by increased expression of perforin and granzyme-B by intratumoral T cells. To conclude, we report that targeting the key Treg transcription factor FOXP3, with ASO FOXP3, has a powerful anti-tumoral effect and enhances T cell response in vitro and in vivo.

    Keywords: ASO, antisense oligonucleotides, Foxp3, Tregs, Cancer, Immunotherapy

    Received: 01 May 2024; Accepted: 29 Jul 2024.

    Copyright: © 2024 Akimova, Wang, Bartosh, Christensen, Eruslanov, Singhal, Aishwarya and Hancock. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Wayne Hancock, Children's Hospital of Philadelphia, Philadelphia, 19104, Pennsylvania, United States

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.