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GITR LIGATION IMPROVES ANTI-PD1-MEDIATED RESTORATION OF HUMAN MMR-PROFICIENT COLORECTAL CARCINOMA TUMOR-DERIVED T CELLS

Open AccessPublished:September 22, 2022DOI:https://doi.org/10.1016/j.jcmgh.2022.09.007
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      Abstract

      Background & Aims

      In contrast to mismatch repair deficient (dMMR) colorectal carcinoma (CRC), MMR proficient (pMMR) CRC does not respond to immune checkpoint blockade (ICB). We studied immune checkpoint stimulation via glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) on ex vivo functionality of human tumor-infiltrating lymphocytes (TIL) isolated from pMMR primary CRC and liver metastases (CRLM).

      Methods

      Using lymphocytes from resected tumor, adjacent tissues, and peripheral blood mononuclear cells (PBMC) of 132 pMMR primary CRC or CRLM patients, we determined GITR expression and the in vitro T-cell agonistic activity of recombinant GITR ligation.

      Results

      Here, we show that GITR was overexpressed on TIL when compared to other stimulatory immune checkpoints (4-1BB, OX40). Its expression was enhanced in TIL compared to PBMC and adjacent tissues. Among CD4+ TIL, GITR expression was primarily expressed by CD45RA- FoxP3hi activated regulatory T cells (aTreg). Within CD8+ TIL, GITR was predominantly expressed on functionally exhausted and putative tumor-reactive CD103+ CD39+ TIL. Strikingly, recombinant GITRL reinvigorated ex vivo TIL responses by significantly enhancing CD4+ and CD8+ TIL numbers. Dual treatment with GITRL and nivolumab (anti-PD1) enhanced CD8+ TIL expansion compared to GITRL monotherapy. Moreover, GITRL/anti-PD1 dual therapy further improved anti-PD1-mediated reinvigoration of interferon-gamma (IFN-γ) secretion by exhausted CD8 TIL from primary CRC.

      Conclusions

      GITR is overexpressed on CD4+ and CD8+ TIL from pMMR CRC and CRLM. Agonistic targeting of GITR enhances ex vivo human TIL functionality and may therefore be a promising approach for novel mono- or combined immunotherapies in primary pMRR CRC and CRLM.

      Graphical abstract

      KEYWORDS

      ABBREVIATIONS:

      (a)Th ((Activated) helper T cell), (a/r)Treg ((Activated/resting) regulatory T cell), dMMR (Mismatch repair deficient), CRC (Primary colorectal carcinoma), CRLM (Colorectal carcinoma-derived liver metastasis), CTL (Cytotoxic T lymphocyte), DN (Double negative), DP (Double positive), FoxP3 (Forkhead box P3), GITR (Glucocorticoid-induced tumor necrosis factor receptor-related protein), GITRL (GITR ligand), GzmA/B (Granzyme A/B), HCC (Hepatocellular carcinoma), ICB (Immune checkpoint blockade), IFNγ (Interferon-gamma), LAG3 (Lymphocyte-activation gene 3), MEM NEAA (Minimum essential medium non-essential amino acids), MFI (Median fluorescence intensity), MSI(-H/-L) (Microsatellite instable(-high/-low)), MSS (Microsatellite stable), PBMC (Peripheral blood mononuclear cells), PD1(hi) (Programmed cell death protein 1(-high)), pMMR (Mismatch repair proficient), sFAS (Soluble FAS), SP (Single positive), TCR (T cell receptor), Tex (Exhausted T cell), Th1 (T helper 1), TIGIT (T cell immunoreceptor with Ig and ITIM domains), TIL (Tumor-infiltrating lymphocytes), TME (Tumor microenvironment), TNFRSF (Tumor necrosis factor receptor superfamily), TNF-α (Tumor necrosis factor-alpha)