# Cell type-directed Tim-3 targeting in melanoma

> **NIH NIH R01** · BRIGHAM AND WOMEN'S HOSPITAL · 2024 · $551,025

## Abstract

PROJECT SUMMARY
Immune checkpoint blockade has elicited unprecedented clinical responses in patients with metastatic
melanoma and other cancers. A promising new checkpoint under investigation in cancer therapeutic trials is T-
cell immunoglobulin and mucin domain 3 (Tim-3). Tim-3 blockade reverses T-cell impairment, thereby
reinvigorating antitumor T-cell immunity. However, we found that Tim-3 inhibitors, including those in clinical
trials, not only target T-cell-Tim-3, but also have varying affinity for Tim-3 on dendritic cells (DCs),
macrophages (MΦs), NK and melanoma cells. Clinical benefit might thus not exclusively rely on antagonism of
T-cell-Tim-3, but also on inhibition of these additional Tim-3-expressing cell types. In support, blockade of T-
cell-Tim-3 suppressed, while melanoma-directed Tim-3 inhibition enhanced tumor growth in murine melanoma
models, thereby counteracting desired efficacy of Tim-3 therapy. Consistently, enforced expression of Tim-3 on
melanoma cells suppressed tumorigenesis, metastasis formation, and proliferative pathway activity. Our
preliminary studies thus identify melanoma cell-intrinsic, DC-, MΦ-, and NK-cell-Tim-3 as unexpected variables
and/or potential confounders of treatment outcome. They further highlight the need to define therapeutic
consequences of Tim-3 antibody (Ab) responses at the level of specific cell types. The Tim-3 protein bears
multiple N- and O-glycostructures that differ dramatically in composition, size, and charge between cell
lineages and which might explain the marked variations in Tim-3 Ab clone reactivity we found between cell
types. For example, the clinical Tim-3 trial candidate, TSR-022, avidly bound T-cell- and melanoma-, but not
NK-, DC-, or MΦ-Tim-3, while other Tim-3 Abs showed high affinity for Tim-3 on T-cells, MΦs, DCs, and/or NK,
but not melanoma cells. Notably, glycan-modifying regimens shifted inhibitor binding towards desired T-cell-
Tim-3 recognition and reduced melanoma-Tim-3 reactivity. Our preliminary data highlights the critical need for
dissecting immune- vs. melanoma cell-Tim-3 glyco-epitopes, Ab affinity, signaling, and immunobiology. Results
will help optimize Tim-3 therapeutic efficacy by validating regimens that preferentially target immune cell-Tim-3
glycans, while avoiding unwanted blockade of melanoma cell-Tim-3. Our aims are to 1) define cell type-
associated Tim-3 glycan moieties, ligands, Ab affinities, and signaling networks, 2) examine immune cell- vs.
melanoma-intrinsic effects of existing Tim-3 antagonists and their relevance to interpreting therapeutic benefit,
and 3) identify new Tim-3 targeting strategies that accentuate immune cell-Tim-3 inhibition. We will use state-
of-the-art gain and loss of Tim-3 function and glycan-modifying strategies, Tim-3 inhibitors with variable tissue-
associated affinities, and immune and melanoma model systems to define cell type-specific Tim-3 functions
and glycomolecular targets. Our initiative also implements cli...

## Key facts

- **NIH application ID:** 10840408
- **Project number:** 5R01CA258637-03
- **Recipient organization:** BRIGHAM AND WOMEN'S HOSPITAL
- **Principal Investigator:** Steven Russell Barthel
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $551,025
- **Award type:** 5
- **Project period:** 2022-06-01 → 2027-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10840408

## Citation

> US National Institutes of Health, RePORTER application 10840408, Cell type-directed Tim-3 targeting in melanoma (5R01CA258637-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10840408. Licensed CC0.

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