# Improving CAR-T efficacy against solid tumors by expanding lymph node reservoirs of “stem-like” CAR-T cells

> **NIH NIH R37** · FRED HUTCHINSON CANCER CENTER · 2024 · $557,041

## Abstract

PROJECT SUMMARY/ABSTRACT
Immunotherapy using CAR-T cells has induced dramatic responses in hematological malignancies, but
extending this success to more common epithelial cancers, which cause the greatest mortality, has proved more
challenging. In a phase 1 trial we conducted, CAR-T cells targeting the tumor-associated antigen ROR1 induced
responses in patients with chronic lymphocytic leukemia but became terminally exhausted in breast and lung
cancer patients, indicating that strategies to preserve CAR-T function are needed to achieve efficacy in solid
tumors. Recent work has demonstrated that a subset of PD-1+Tcf1+ “precursor” exhausted cells (Tpex) is critical
for mediating successful tumor responses to immunotherapy. Tpex retain a stem-like capacity for self-renewal,
proliferation, and the ability to differentiate into effector-like cells. Interestingly, Tpex preferentially co-localize
with antigen-presenting cells (APCs) and reside in tumor-draining lymph nodes (tdLN), where they may be
protected from factors in tumors that drive terminal exhaustion, such as more chronic antigen stimulation, mTOR
activation, and hypoxia. Unlike conventional T cells, CAR-T cells are activated by intact antigen expressed on
tumor cells, not by peptide/MHC complexes expressed on both tumor cells and APCs. This design restricts CAR-
T activation exclusively to tumors, where preservation of stem-like qualities may be impaired relative to tdLNs.
To test this, we developed a Kras/p53 (KP) autochthonous model of ROR1+ lung cancer that recapitulates the
dysfunction of ROR1 CAR-T cells we observed in patients. Using this model, we found ROR1 CAR-T cells did
not accumulate in tdLNs and showed faster attrition of Tpex and terminal exhaustion in tumors compared to
tumor-specific T cells (TCR-T) that were cultured identically prior to infusion. Tcf1+ CAR-T cells showed greater
proliferative capacity, stem-like self-renewal, and tumor control compared to Tcf1- CAR-T cells, suggesting that
strategies to preserve Tcf1+ CAR-Ts could significantly improve efficacy. Interestingly, CAR-T cells in tdLNs
formed a small reservoir of “pre-exhausted” PD-1-Tcf1+ central memory cells that we could increase by
vaccination and that may be able to generate more polyfunctional effectors than Tpex, which are epigenetically
committed to producing hypofunctional effectors. We hypothesize that insufficient activation of CAR-T cells by
APCs in tdLNs impairs maintenance of stem-like Tpex reservoirs, resulting in less durable tumor control, and
that using vaccination to increase reserves of Tcf1+ CAR-T cells in LNs will overcome this barrier. In this proposal,
we will use the KP model to determine: 1) whether CAR-T are impaired in maintaining a stem-like Tcf1+ reservoir
relative to TCR-T cells and whether this is due to insufficient activation by APCs; and 2) whether activating CAR-
T cells with endogenous APCs in LNs via a novel vaccine platform will improve numbers of Tcf1+ CAR-T cells,
tumor ...

## Key facts

- **NIH application ID:** 10912724
- **Project number:** 5R37CA276285-02
- **Recipient organization:** FRED HUTCHINSON CANCER CENTER
- **Principal Investigator:** Shivani Srivastava
- **Activity code:** R37 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $557,041
- **Award type:** 5
- **Project period:** 2023-07-01 → 2028-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10912724

## Citation

> US National Institutes of Health, RePORTER application 10912724, Improving CAR-T efficacy against solid tumors by expanding lymph node reservoirs of “stem-like” CAR-T cells (5R37CA276285-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10912724. Licensed CC0.

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