# Replication stress response defects predict and enhance immune checkpoint therapy response in triple negative breast cancer

> **NIH NIH R01** · UNIVERSITY OF TX MD ANDERSON CAN CTR · 2022 · $362,016

## Abstract

Project Summary
The lack of specific targets for the treatment of triple-negative breast cancer (TNBC) is a major challenge, as
many TNBCs do not respond to cytotoxic chemotherapies. Immune checkpoint blockade (ICB) has yielded
promising results in both advanced and early-stage TNBC and is expected to substantially improve the overall
prognosis of patients with this disease. However, since TNBC is not inherently immunogenic, it is important to
identify patients who would benefit most from immunotherapy and to identify agents that can prime the tumor
microenvironment to enhance the therapeutic effects. TNBC is known to exhibit high levels of replication stress,
which occurs when the DNA replication machinery encounters obstacles that impede the replication process. In
normal cells, replication stress activates the replication stress response (RSR) to maintain genome integrity.
Defective RSR allows cells with high replication stress to survive and proliferate. Recently, we have identified a
gene signature that represents defects in RSR (RSRD). We found this RSRD signature to be highly enriched in
TNBC cells. Furthermore, RSRD-high TNBC cells accumulate cytoplasmic DNA and induce STING-dependent
cytokine production, which is required for the effectiveness of ICB. Intriguingly, the RSRD signature score
correlates perfectly with the response of TNBC to ICB in syngeneic mouse models, and it accurately predicts
ICB response across 5 low–mutation-burden tumor lineages. All these intriguing findings support the hypotheses
that RSRD may act as a key determinant of ICB outcomes in low–mutation-burden cancers, including TNBC,
and that RSRD-enhancing drugs may sensitize ICB-resistant TNBC to immunotherapy. These hypotheses will
be tested via 3 specific aims. (1) To determine how the immune microenvironment is modified in RSR-defective
TNBC. We will use a highly multiplexed imaging mass cytometry panel to determine how RSRD remodels the
immune microenvironment of TNBC and induces susceptibility to ICB. In addition, we will manipulate the RSR
status in TNBC cells to assess the relationship between RSR defects and immunotherapy response. (2) To
identify causative drivers of RSRD-high–mediated ICB responsiveness in TNBC. Our preliminary studies suggest
that RSR defects may drive immunotherapy response through accumulation of immunostimulatory cytosolic
single-stranded DNA (ssDNA). We will, therefore, seek to manipulate the cytosolic ssDNA level in TNBC models
to determine whether cytosolic ssDNA is indeed a causative driver of ICB responsiveness in TNBC. In addition,
to understand why our RSRD gene signature predicts response to ICB in TNBC, we will apply an in vivo CRISPR
screen to determine what transcriptional changes contained within our RSRD gene signature cause this
response. (3) To develop novel combination therapy to convert RSRD-low TNBC to RSRD-high to improve their
response to ICB. Using cutting-edge systems and bioinformatics approaches, we have ident...

## Key facts

- **NIH application ID:** 10330595
- **Project number:** 5R01CA247862-02
- **Recipient organization:** UNIVERSITY OF TX MD ANDERSON CAN CTR
- **Principal Investigator:** Shiaw-Yih Lin
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $362,016
- **Award type:** 5
- **Project period:** 2021-02-01 → 2026-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10330595

## Citation

> US National Institutes of Health, RePORTER application 10330595, Replication stress response defects predict and enhance immune checkpoint therapy response in triple negative breast cancer (5R01CA247862-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10330595. Licensed CC0.

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