# Non-Invasive Detection of Tumor Extracellular pH using Multispectral Optoacoustic Tomography

> **NIH NIH R01** · UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR · 2020 · $323,588

## Abstract

Malignant melanoma is one of the fastest rising cancers in the US. While treatment for clinical stage I and II
melanoma involves wide local excision of the primary tumor, with staging of the regional lymph nodes by
sentinel lymph node (SLN) biopsy, SLN biopsy is fraught with false-negative results. Technology that would
reliably detect nodal metastases, not just the first draining node, could improve the sensitivity of melanoma
nodal staging. Therefore, our objective is to (1) develop, characterize, validate and compare (A) optoacoustic
ultra-acidic pH-responsive acidic pH targeted dye, pHO dye, and (B) external cell membrane anchored, V7-
pHO, for tumor detection by multispectral optoacoustic tomography (MSOT) and (2) provide real-time color
maps of tissue pH to allow for identification of regions of tumor in lymph nodes. Based on our preliminary data,
we reason that it is possible to use our targeting methodology to identify very small metastases, which would
allow complete lymph node dissection to be performed only for the 15% to 20% of patients who actually have
cancer in the non-sentinel nodes. We hypothesize that pHO and V7-pHO dyes will facilitate detection of
melanoma within lymph nodes and differentiate it from non-malignant, fibrous, or inflammatory tissue with high
sensitivity and specificity using multispectral optoacoustic tomography. To test our hypothesis, we propose the
following aims: 1) characterize and validate pHO and V7-pHO dyes to target acidic pHe for detection of tumor
cells in vitro and in tissue phantoms; 2) assess pHO and V7-pHO dyes to facilitate detection of melanoma from
non-malignant tissue in vivo using multispectral optoacoustic tomography; and 3) develop ratiometric
algorithms based upon the spectral modulation of the pHO and V7-pHO dyes to produce real-time pHe
measurement color maps and bi-color maps of tumors. Successful identification of melanoma containing lymph
nodes using pHO or V7-pHO dyes detected using MSOT has potential to stratify patients for treatment in the
clinic. Identification of metastases in lymph nodes or elsewhere in melanoma patients has potential for game-
changing clinical management of patients with melanoma.

## Key facts

- **NIH application ID:** 10113705
- **Project number:** 7R01CA205941-05
- **Recipient organization:** UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR
- **Principal Investigator:** Lacey R McNally
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $323,588
- **Award type:** 7
- **Project period:** 2016-09-01 → 2022-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10113705

## Citation

> US National Institutes of Health, RePORTER application 10113705, Non-Invasive Detection of Tumor Extracellular pH using Multispectral Optoacoustic Tomography (7R01CA205941-05). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10113705. Licensed CC0.

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