# Proj. 3: Immunosuppressive circuits in T cells and other immune cells in GBM patients enrolled in clinical trials

> **NIH NIH P01** · BRIGHAM AND WOMEN'S HOSPITAL · 2021 · $359,181

## Abstract

Abstract
T cells are central effector cells of protective anti-tumor immunity, but little is currently known about these
important immune cells in human GBM. We have generated single-cell RNA-seq data on tumor-infiltrating T cell
populations from GBM patients at initial diagnosis or relapse. We used these full-length RNA-seq data to identify
clonally expanded T cell populations based on their TCRα and β chain sequences and then examined which
genes were overexpressed by such expanded T cells. This analysis highlighted the KLRB1 gene which encodes
the CD161 receptor that was previously shown to inhibit NK cell-mediated cytotoxicity. The CD161 ligand,
CLEC2D, is expressed at the cell surface of human GBM cells. We therefore hypothesize that the CD161 –
CLEC2D pathway inhibits the anti-tumor function of both CD8 and CD4 effector T cell populations in
GBM. Preliminary data show that inactivation of the KLRB1 gene in primary human T cells greatly enhances
their effector function in a humanized mouse model of GBM. Our preliminary data also demonstrate that several
other inhibitory receptors are expressed by substantial populations of GBM-infiltrating T cells, including CD96
and two prostaglandin E2 receptors (EP2 and EP4). Aim 1 will focus on the analysis of tumor-infiltrating T cells
in GBM patients enrolled in the phase 1b NeoVax plus PD-1 antibody trial described in Project 1. These studies
will primarily focus on the expression of inhibitory receptors by T cells and their ligands by tumor cells and myeloid
cells. Expression of inhibitory receptors and their ligands will be examined by 16-color spectral flow cytometry
and single-cell RNA-seq (in collaboration with Cores 1 and 2), with an emphasis on CD161, PD-1, CD96 and
prostaglandin E2 receptors. We will investigate paired tumor samples from the same patient obtained at initial
surgery and relapse in order to determine how expression of these inhibitory receptors and their ligands changes
following immunotherapy with NeoVax plus PD-1 antibody. In collaboration with Project 1, we will also examine
the spatial distribution of T cells that express CD161 and other inhibitory receptors. Aim 2 will investigate the
therapeutic significance of the CD161 – CLEC2D pathway. We will first use a genetic approach to study this
inhibitory receptor by inactivating the KLRB1 gene in primary T cells. Blocking mAbs specific for human CD161
will also be used to examine the therapeutic potential of these findings. We will also examine combination
therapies (collaboration with Projects 2, 4 and Core 3) involving the inhibitory receptors identified by single-cell
RNA-seq in human GBM infiltrating T cells, with a particular focus on CD161, PD-1, CD96 and the prostaglandin
E2 receptors. These studies will significantly advance our understanding of T cell function in GBM and
characterize important inhibitory receptor – ligand interactions that constrain effector T cell function.

## Key facts

- **NIH application ID:** 10210221
- **Project number:** 5P01CA236749-02
- **Recipient organization:** BRIGHAM AND WOMEN'S HOSPITAL
- **Principal Investigator:** Kai W Wucherpfennig
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $359,181
- **Award type:** 5
- **Project period:** 2020-07-03 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10210221

## Citation

> US National Institutes of Health, RePORTER application 10210221, Proj. 3: Immunosuppressive circuits in T cells and other immune cells in GBM patients enrolled in clinical trials (5P01CA236749-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10210221. Licensed CC0.

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