# Discovery of Novel Therapeutic Strategies for Cancer Immunotherapy

> **NIH NIH F99** · YALE UNIVERSITY · 2024 · $50,474

## Abstract

Project Summary
 The central hypothesis of my F99-phase proposal is that the lack of T-cell infiltration into human tumors may
be caused by the presence of tumor-derived T-cell excluders (TCEs) in the TME, which are overexpressed in
tumor tissues and impair the function of T cells including their ability to migrate into tumor tissues. This provides
a potential explanation why both spontaneous and therapeutic T cell-mediated anti-tumor immunity fail frequently
in patients with immunologically “cold” tumors. By employing a secretome-wide in vitro T-cell transwell migration
high-throughput screening (HTS) platform, we tested over a thousand soluble human proteins on the migration
of activated T cells towards chemokine signal. SLIT2 was identified as a candidate target and validated to directly
inhibit T-cell chemotaxis towards CXCL11, a common chemokine found in human tumor tissues.
 The N-terminal fragment of SLIT2 was first confirmed to mediate T-cell chemotaxis inhibition. Detailed
functional domain mapping demonstrated that the first two leucine-rich repeat (LRR) domains, where the
canonical receptor ROBO1 binds, are dispensable to SLIT2’s function in regulating T-cell chemotaxis. Meanwhile,
ROBO1 expression could not be detected on T-cell surface with FACS staining, and soluble ROBO1 extracellular
fragment fusion protein failed to neutralize SLIT2’s inhibitory effect on T cells, collectively suggesting a novel T-
cell specific SLIT2 signaling axis independent of ROBO1. In a syngeneic mouse pancreatic cancer model,
dramatically elevated T-cell infiltrated was observed in SLIT2 knock-out Pan02 tumors. SLIT2-KO tumors were
rejected by the immune-competent C57BL/6 mice, while the SLIT2 wild-type tumors grew. Such difference
diminished when the SLIT2-WT/KO tumors were inoculated into immune-compromised NSG mice. Anti-SLIT2
monoclonal antibody 11C8 neutralized the inhibitory effect of SLIT2 on T-cell chemotaxis in vitro, and its single-
agent treatment led to Pan02 tumor regression in vivo. The functional SLIT2 receptor expressed on T cells, the
broader impact of tumoral SLIT2 to the immune contexture within the TME, and the potential synergistic effect
of anti-SLIT2/anti-PD-1 combo are subject to further investigation during the F99 phase training.
 In the K00 phase of this proposal, I would like to expand my study to understand dysfunction of T cells during
tumor progression. These studies might include the discovery of additional TME-specific extracellular factors
that drive dysfunctional anti-tumor immunity in T-cell inflamed tumors. I propose to establish in vitro HTS
platforms to identify candidate targets that (1) promote central memory T-cell phenotype that favors egression
into secondary lymphoid organs, (2) reduce T-cell proliferative capacity and induce apoptotic signatures, (3)
suppress T-cell effector functions and drive exhaustion phenotype. Multi-omics studies and inducible expression
animal models will be utilized in parallel for targ...

## Key facts

- **NIH application ID:** 10988986
- **Project number:** 1F99CA294168-01
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** Xuan Yang
- **Activity code:** F99 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $50,474
- **Award type:** 1
- **Project period:** 2024-09-01 → 2025-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10988986

## Citation

> US National Institutes of Health, RePORTER application 10988986, Discovery of Novel Therapeutic Strategies for Cancer Immunotherapy (1F99CA294168-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10988986. Licensed CC0.

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