# Mechanisms of tumor microenvironmental regulation of T-cell infiltration in melanoma

> **NIH NIH F31** · HARVARD MEDICAL SCHOOL · 2021 · $39,551

## Abstract

Project Summary
 Melanoma is the deadliest form of skin cancer, with over 100,000 new cases and 6,000 deaths predicted
in the United States in 2020. While the advent of immune checkpoint blockade has greatly improved the
prognoses of advanced-stage patients, 64% of patients progress within 5 years post-treatment, indicating a
critical need to improve efficacy in non-responders. Recent evidence has demonstrated that tumor-infiltrating
lymphocytes are a positive prognostic indicator and a biomarker predictive of response to immune checkpoint
blockade. Strategies to increase T-cell infiltration of tumors therefore have strong therapeutic potential. Here, I
propose to elucidate the dynamics and mechanistic determinants of T-cell infiltration using an endogenous
zebrafish melanoma model that demonstrates a robust immune response by the native zebrafish immune
system. I hypothesize that cells in the tumor microenvironment are critical regulators of T-cell infiltration in tumors
by alteration of the cytokine milieu and extra-cellular matrix which create an immunogenic or immunosuppressive
niche. In aim 1, I seek to describe the dynamic process of T-cell infiltration in an endogenous zebrafish melanoma
model using a novel CD8+ reporter line marking cytotoxic T cells and a pan-T cell reporter line. Our ability to
generate endogenous, non-pigmented melanomas in the zebrafish allows for non-invasive visualization of the
complex, in vivo tumor microenvironment throughout tumor development. I will additionally visualize interactions
between T cells and the tumor niche using fluorescent reporters that label prevalent cells in the tumor
microenvironment, including stromal cells, endothelial cells, and myeloid cells. I will then use single-cell ATAC-
sequencing to characterize distinct T-cell subpopulations, identify T-cell subtype-specific regulatory regions, and
develop fluorescent reporters for T cells of immunogenic and immunosuppressive tumors. These reporters will
enable me to observe T-cell activity in vivo and establish a system to identify factors that modify T-cell behavior
in immunogenic and immunosuppressed tumors. In aim 2, I propose to use single-cell RNA-sequencing of
zebrafish melanomas to identify transcriptionally-distinct cellular subpopulations in the tumor microenvironment
of T cell-infiltrated or non-infiltrated tumors. This will identify key microenvironmental genes and pathways that
demarcate T-cell infiltration. I will functionally evaluate candidate pathways in vivo using tissue-specific
expression vectors overexpressing or knocking out relevant genes. Collectively, these proposed experiments
will advance understanding of the mechanisms underlying the anti-tumor response in order to allow for the
development of therapeutics to induce T-cell infiltration and expand the population of responders to
immunotherapy.

## Key facts

- **NIH application ID:** 10227371
- **Project number:** 1F31CA260802-01
- **Recipient organization:** HARVARD MEDICAL SCHOOL
- **Principal Investigator:** Georgia Stirtz
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $39,551
- **Award type:** 1
- **Project period:** 2021-04-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10227371

## Citation

> US National Institutes of Health, RePORTER application 10227371, Mechanisms of tumor microenvironmental regulation of T-cell infiltration in melanoma (1F31CA260802-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10227371. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*