# Project 2 - Preclinical studies: Overcoming tumor heterogeneity

> **NIH NIH P01** · UNIVERSITY OF PENNSYLVANIA · 2021 · $515,359

## Abstract

Project 2. Preclinical Trials
Abstract
Non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MPM) are highly lethal cancers with
suboptimal therapies. The goal of this Program Project and of Project 2 is to successfully implement the use of
T cells expressing chimeric antigen receptors (CARs), an approach that has been highly successful in
leukemias. Our group was among the first to inititate CAR T cell trials focused on solid tumors by targeting the
tumor-associated antigen mesothelin. However, despite showing safety and feasibility, therapeutic efficacy
was limited. We hypothesize that one of the important issues limiting success in solid tumors is tumor antigen
heterogeneity. Even at baseline, it is likely that not all tumor cells will express the targeted antigen. The
primary focus of this Project will be to explore ways to overcome heterogeneity in solid tumor CAR T
cell therapy. Our first approach will be to attack the tumor stroma. We previously showed that CAR T cells
targeted to mouse fibroblast activation protein (FAP) on tumor fibroblasts can decrease the tumor matrix,
augment endogenous intratumoral T cells, and slow tumor growth with minimal toxicity. In Aim 1, we propose
to study a CAR targeted to human FAP that can be used in our clinical trial. In Aim 1A, we will assess the
efficacy of the anti-human-CAR T cells using a new mouse model which combines human CAFs and human
tumors in immunodeficient mice. In Aim 1B, we will evaluate the safety of anti-human FAP CAR T cells on
primary human cell lines. In Aim 1C, we will evaluate combination therapies using the stromal-targeted CAR
(FAP-CAR) with a tumor-cell targeted CAR (mesothelin-CAR). In Aim 2, we will explore the key issue of
whether mesothelin and FAP CARs are able to induce bystander effects. In Aim 2A, we will study CAR-
induced bystander effects by injecting mice with varying ratio's of tumor cells expressing or not expressing
mesothelin and defining bystander effect as the minimal percentage of non-targeted tumor cells that still allow
tumor elimination. Additional studies are proposed to determine the mechanisms by which the bystander effect
occurs. In Aim 2B, the process of epitope spreading will be studied by determining the ability of Meso- and
FAP-CARs to induce or stimulate endogenous T cells directed against tumors expressing a xenoantigen, a
viral antigen, and a neoantigen. We will define the amount of baseline epitope spreading that is present using
tetramer assays and a T cell cross presentation proliferation assay. In Aim 3, we will explore ways in which
CAR-induced antigen spreading can be augmented by immune activators such as antibodies to PD1 and
CTLA-4 or an IDO inhibitor (Aim 3A) and by genetically altering CAR T cells to produce FMS-like tyrosine
kinase 3 ligand (FLT3L), a powerful inducer of dendritic cells (Aim 3B). Successful completion of these
studies will provide key information for the field of adoptive transfer of T cells for solid...

## Key facts

- **NIH application ID:** 10241978
- **Project number:** 5P01CA217805-04
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Steven Mark Albelda
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $515,359
- **Award type:** 5
- **Project period:** 2018-09-14 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10241978

## Citation

> US National Institutes of Health, RePORTER application 10241978, Project 2 - Preclinical studies: Overcoming tumor heterogeneity (5P01CA217805-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10241978. Licensed CC0.

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