# (PQ#3) Novel tumor intrinsic PD-L1 signals direct tumor immune cell infiltration

> **NIH NIH R01** · UNIVERSITY OF TEXAS HLTH SCIENCE CENTER · 2021 · $640,569

## Abstract

We respond to PQ3 with our data showing that tumor PD-L1 (CD274, B7-H1) is a major regulator of tumor
inflammatory infiltrates. Our preliminary data show that melanoma PD-L1 regulates TIL through several
previously unknown tumor-intrinsic and extrinsic mechanisms. We define novel effects of tumor intrinsic PD-L1
signaling on tumor proliferation, sensitivity to immune killing, in vivo growth independent of anti-tumor
immunity, and regulation of mTOR signals. We identified intracellular PD-L1, including those whose surface
expression is low or negative, and identified interactions with tumor PD-1. We hypothesize that melanoma
intrinsic PD-L1-driven signals, particularly mTOR signals, alter tumor progression and treatment
responses. The research team is comprised of tumor immunotherapy, tumor immunology and PD-L1 experts
at UTHSCSA and Dartmouth. We focus on melanoma for scientific reasons and based on our expertise.
Aim 1 Define how tumor PD-L1 alters tumor immune infiltrates and immunotherapy responses. We use
control versus PD-L1lo (shRNA) B16 in a novel model to study differential treatment outcomes by tumor PD-L1
status. We generated PD-L1KO B16 by CRISPR for highly detailed follow up mechanistic studies, and to assess
if PD-L1 null status differentially affects treatment versus PD-L1lo. Effects will also be tested in transplanted
BrafV600E mutated D4M melanoma (PD-L1+) engineered to be PD-L1lo and PD-L1KO, in mice with induced
BrafV600E melanomas, and in syngeneic skin grafts of skin from Braf/Pten versus PD-L1KO Braf/Pten mice.
Aim 2 Test tumor PD-L1-driven mTOR signal effects on TIL and immunotherapy responses. We will test
PD-L1 KO, PD-1 KO and double KO melanoma cells for mTOR signals, TIL and treatment effects. Cells will be
engineered for defects in mTORC1/2 for mechanistic studies, complemented with mTOR inhibitor treatments.
We will use engineered tumors that express cytoplasm-only versus cell surface-only PD-L1, to define novel,
intracellular PD-L1 signals. Constructs with mutations in known PD-1 signal sites will be engineered into these
tumors for a complete understanding of PD-L1/PD-1 interactions.
Aim 3 Define cell-intrinsic PD-L1 effects in human melanoma. We use well-defined human melanoma lines
that are basal PD-L1+ and/or PD-1+ and/or BrafV600E mutated. We will use human vectors to knock down or
knock out PD-L1, PD-1 and mTORC1/2 genes. In vitro assessments of effects on proliferation, responses to
mTOR inhibitors, αPD-L1 and αPD-1 will be assessed. In vivo effects in NSG mice will be assessed. Primary
human melanoma lines will be studied to complement data from long-term lines.

## Key facts

- **NIH application ID:** 10160809
- **Project number:** 5R01CA205965-05
- **Recipient organization:** UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
- **Principal Investigator:** William Brian Reeves
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $640,569
- **Award type:** 5
- **Project period:** 2017-06-01 → 2024-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10160809

## Citation

> US National Institutes of Health, RePORTER application 10160809, (PQ#3) Novel tumor intrinsic PD-L1 signals direct tumor immune cell infiltration (5R01CA205965-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10160809. Licensed CC0.

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