PD-1 blockade restores helper activity of tumor-infiltrating, exhausted PD-1hiCD39+ CD4 T cells.

Camille-Charlotte Balança,Carine Valle,Frédéric Pont,Gwénaël Ferron,Marie Michelas,Victor Sarradin,Maha Ayyoub,Philippe Rochaix,Laurence Gladieff,Christel Devaud,Clara-Maria Scarlata,Anna Salvioni,Marie Tosolini,Jean‐Pierre Delord ,Carlos Gomez‐Roca ,Alejandra Martínez ,Eliane Mery-Lamarche ,S Vergez ,Carlos Martínez-Gómez ,Jean‐Jacques Fournié ,Agnès Dupret‐Bories

doi:10.1172/jci.insight.142513

Abstract

Tumor antigen–specific CD4 T cells accumulate at tumor sites, evoking their involvement in antitumor effector functions in situ. Contrary to CD8 cytotoxic T lymphocyte exhaustion, that of CD4 T cells remains poorly appreciated. Here, using phenotypic, transcriptomic, and functional approaches, we characterized CD4 T cell exhaustion in patients with head and neck, cervical, and ovarian cancer. We identified a CD4 tumor-infiltrating lymphocyte (TIL) population, defined by high PD-1 and CD39 expression, which contained high proportions of cytokine-producing cells, although the quantity of cytokines produced by these cells was low, evoking an exhausted state. Terminal exhaustion of CD4 TILs was instated regardless of TIM-3 expression, suggesting divergence with CD8 T cell exhaustion. scRNA-Seq and further phenotypic analyses uncovered similarities with the CD8 T cell exhaustion program. In particular, PD-1hiCD39+ CD4 TILs expressed the exhaustion transcription factor TOX and the chemokine CXCL13 and were tumor antigen specific. In vitro, PD-1 blockade enhanced CD4 TIL activation, as evidenced by increased CD154 expression and cytokine secretion, leading to improved dendritic cell maturation and consequently higher tumor-specific CD8 T cell proliferation. Our data identify exhausted CD4 TILs as players in responsiveness to immune checkpoint blockade.

Highlights

By virtue of their direct antitumor cytotoxic effector functions, CD8 T cells have been at the core of antitumor immunity investigations
We showed that tumor Ag–specific CD4 T cells accumulate at tumor sites, where they are found at higher proportions than in the circulation, supporting their involvement in direct or indirect antitumor effector functions in situ (1, 5)
We identified high expression of PD-1 associated with CD39 expression as markers of CD4 T cell exhaustion in situ in 3 epithelial malignancies

Summary

Introduction

By virtue of their direct antitumor cytotoxic effector functions, CD8 T cells have been at the core of antitumor immunity investigations. Others, have shown that circulating CD4 T cells specific for tumor antigens (Ags) are detectable in patients bearing Ag+ tumors (1, 2). The contribution of CD4 T cells to CD8 T cell priming, whereby CD4 T cells help foster clonal expansion and acquisition of CD8 T cell memory and effector functions, is generally acknowledged (3). In addition to their foreseeable role at the priming phase and despite the lack of MHC class II molecule expression in the vast majority of tumor cells, CD4 T cells are thought to exert effector functions through for instance IFN-γ secretion (4). We showed that tumor Ag–specific CD4 T cells accumulate at tumor sites, where they are found at higher proportions than in the circulation, supporting their involvement in direct or indirect antitumor effector functions in situ (1, 5). The presence of tumor-specific CD4 T cells, at the tumor site, was shown to be necessary for immune-mediated tumor rejection (6)

Methods

Results

Conclusion