# Imaging tumor-associated macrophages in head and neck squamous cell carcinoma using fluorine-19 MRI

> **NIH CA R01** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2026 · $655,700

## Abstract

In this project, we aim to translate a fluorine-19 (19F) MRI technology to visualize the tumor associated
macrophage (TAM) burden in patients with recurrent head and neck squamous cell carcinoma (HNSCC).
HNSCC is the sixth most common cancer worldwide. TAMs often comprise a significant volume fraction of tumor
mass, and a high TAM burden in the tumor microenvironment is associated with poor therapeutic prognosis. In
HNSCC patients developing locoregionally recurrent or metastatic disease, anti-PD-1 antibody checkpoint
inhibitor therapy is currently the standard of care, however, the response rates remain poor (~20%). TAMs have
been associated with immunosuppression and T-cell exclusion, which are associated with a low response rate
to checkpoint inhibitors. Thus, there is an urgent need for biomarker probes that can non-invasively monitor
TAMs in clinical trials to help stratify patients and rationally optimize therapeutic strategies. Towards this goal,
we propose translating a fast-clearing perfluorocarbon (PFC) nanoemulsion as a 19F MRI tracer to assay TAMs
in vivo. Following intravenous injection, the size and morphology of nonbiologic PFC nanoemulsion droplets
make them susceptible to endocytosis by phagocytic immune cells, particularly macrophages. The in situ labeled
cells accumulate at inflammatory lesions, and the resulting 19F MRI hot-spots can be quantified, where the signal
is linearly proportional to the macrophage burden. In situ PFC macrophage labeling has been used in a multitude
of preclinical inflammation models, including in the context of TAMs. However, no injectable, clinical PFC
nanoemulsion imaging agent product exists despite the proven specificity and safety of these compositions.
Building on this work, the proposal has three Specific Aims: Aim 1. Perfluorocarbon NE formulation. This aim will
identify a lead formulation and collaborate with a contract manufacturing organization to produce a novel
nanoemulsion composition (“TAM-Sense”) at lite

## Key facts

- **NIH application ID:** 11319716
- **Project number:** 5R01CA290014-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** ERIC T. AHRENS; Joseph A Califano
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** CA
- **Fiscal year:** 2026
- **Award amount:** $655,700
- **Award type:** 5
- **Project period:** 2024-05-01T00:00:00 → 2029-04-30T00:00:00

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11319716

## Citation

> US National Institutes of Health, RePORTER application 11319716, Imaging tumor-associated macrophages in head and neck squamous cell carcinoma using fluorine-19 MRI (5R01CA290014-03). Retrieved via AI Analytics 2026-07-13 from https://api.ai-analytics.org/grant/nih/11319716. Licensed CC0.

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