# The role of antigen binding strength in CAR T cell activity

> **NIH NIH K08** · CHILDREN'S HOSPITAL OF LOS ANGELES · 2020 · $173,198

## Abstract

PROJECT SUMMARY/ABSTRACT
Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of pediatric patients with
hematologic malignancies, yet robust responses to this modality in solid tumors have been lacking. As a result,
most pediatric patients with relapsed or refractory solid tumors remain in dire need of alternative therapy. Given
the inhospitable solid tumor microenvironment, we are unlikely to achieve robust responses without the most
highly potent CAR T cells. My previous studies in vitro and in mice have demonstrated that CAR T cell potency
can be enhanced by increasing the affinity of CAR for its cognate antigen. Further investigation revealed that in
particular cytotoxicity was enhanced, whereas T cell survival and central memory (Tcm) differentiation (both
important in CAR T clinical persistence and efficacy) were actually impaired in the high affinity CAR T cells.
These findings raise questions regarding the cellular signaling events underlying these discordant effects and
highlight the possibility that by reversing these decrements in survival and memory in the high affinity cells, CAR
T cell potency could be unleashed even further. This mentored career development proposal will test the
hypothesis that increased CAR affinity results in faster and more sustained activation of downstream T cell
signaling pathways, enhancing cytotoxic granule release yet overly engaging signaling molecules such as ERK
and Akt, tipping the cellular balance away from survival and memory differentiation and toward cell death. To
test the hypothesis, I will use selected panels of affinity variants to evaluate the relationship between CAR affinity
and the activation kinetics of key signaling pathways by quantitative Western blot. I will further evaluate the
impact of CAR affinity on both cytotoxic granule release using microscopy as well as T cell survival and memory
differentiation in vitro using flow cytometry. Lastly, I will identify and evaluate targetable mediators of the survival
balance operating in high affinity CAR T cells in vitro and in tumor-bearing mice. To do so, I will compare the
affinity variant CAR T cells’ survival and Tcm differentiation in the presence or absence of specific inhibitors of
pathways (MEK, Akt, and Fas) that when over-activated can impair T cell survival or memory differentiation.
These studies are expected to yield potent CAR T cells equipped to address the challenge of solid tumors where
both efficient killing and robust persistence are necessary for efficacy. This work is to be completed under the
co-mentorship of Drs. Michael Milone and Stephan Grupp and with the guidance of my Scientific Advisory
Committee members Drs. Burkhardt, Kambayashi, and Dustin. The training plan developed for this proposal is
designed to provide me with skills such as advanced microscopy techniques that are necessary to best address
the proposed research questions. The scientific and training components of this proposal ...

## Key facts

- **NIH application ID:** 10311364
- **Project number:** 7K08CA237868-03
- **Recipient organization:** CHILDREN'S HOSPITAL OF LOS ANGELES
- **Principal Investigator:** SARAH ANN RICHMAN
- **Activity code:** K08 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $173,198
- **Award type:** 7
- **Project period:** 2019-07-05 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10311364

## Citation

> US National Institutes of Health, RePORTER application 10311364, The role of antigen binding strength in CAR T cell activity (7K08CA237868-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10311364. Licensed CC0.

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