# Targeting immunosuppression of intratumoral CAR T cells

> **NIH NIH R01** · UNIVERSITY OF PENNSYLVANIA · 2024 · $527,840

## Abstract

ABSTRACT
 The clinical benefits of cancer immunotherapies, including adoptive cell transfer (ACT) of chimeric antigen
receptor (CAR) T cells, are limited when used against solid tumors. The immuno-suppressive tumor
microenvironment (TME) is enriched in cellular components (regulatory T cells, myeloid derived suppressor
cells, tumor-associated macrophages, etc) and acellular factors (hypoxia, deficit of nutrients, acidosis,
adenosine, etc) that decrease viability and tumoricidal activities of anti-tumor native CD8+ cytotoxic T
lymphocytes (CTL) and of therapeutic CAR T cells. Therapeutic neutralization of these factors and components
is challenging because of their diversity and redundancy. Instead, we aim to identify and thwart the key
mechanisms by which the TME-derived factors and conditions undermine viability and the anti-tumor activities
of CAR T cells. We will focus on TME-triggered downregulation of type I interferon (IFN1) receptor IFNAR1,
which normally supports viability and activity of native CTLs and CAR T cells. Our preliminary data show that
MAPK Activated Protein Kinase 2 (MK2) and mono-ADP-ribosyl transferase PARP11 cooperate to
downregulate IFNAR1 on intratumoral CAR-bearing T cells, leading to their inactivation and rapid cell death.
IFNAR1 loss leads to downregulation of IFN1-inducible cholesterol 25-hydroxylase (CH25H). CH25H acts to
limit the effector trogocytosis between malignant cells and specific CAR T cells. In the absence of sufficient
levels of CH25H and its product 25-hydroxycholesterol (25HC), this trogocytosis undermines the activities of
CAR T cells and exposes them to fratricidal killing. These and other exciting preliminary results suggest an
overarching hypothesis that targeting TME-driven PARP11/MK2/CH25H-dependent mechanisms that regulate
the viability and activity of CAR T cells should enhance their anti-tumor activities and increase the efficacy of
CAR T ACT. To test this hypothesis, we will determine (i) the roles of TME-induced PARP11 in inactivation of
CAR T cells, (ii) the importance of MK2 activity in suppression of intratumoral CAR T cells and (iii) the
contribution of downregulation of CH25H in CAR T cells inactivation and decreased efficacy of CAR T ACT.
 Completion of these studies should gain insight into immunosuppression of intratumoral CAR T cells and
help to develop novel CAR constructs and CAR T pre-treatments as well as combinatorial approaches to
increase the efficacy of CAR T ACT.

## Key facts

- **NIH application ID:** 10770655
- **Project number:** 1R01CA285321-01
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Michael S Cohen
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $527,840
- **Award type:** 1
- **Project period:** 2024-02-01 → 2029-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10770655

## Citation

> US National Institutes of Health, RePORTER application 10770655, Targeting immunosuppression of intratumoral CAR T cells (1R01CA285321-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10770655. Licensed CC0.

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