# Therapeutic strategies for treatment of giant congenital melanocytic nevi

> **NIH NIH R01** · MASSACHUSETTS GENERAL HOSPITAL · 2024 · $96,504

## Abstract

Abstract
Congenital Melanocytic Nevi (CMN) can reach giant sizes, transform to melanoma during childhood, and
therefore trigger pre-emptive surgery with permanent profound morbidity. During the prior funding period, we
constructed four CMN models to test regression-inducing treatments to avoid surgery. Three were genetically
engineered mice driven by the (floxed)NRASQ61R oncogene, responsible for most human CMN, with melanocyte-
targeting via tamoxifen-inducible or constitutive expression from Tyr or Dct promoters. The fourth model
employed xenografts of human CMNs on immunodeficient mice. Two models displayed substantial
transformation to melanoma after long latency. Inducible modeling clarified the proliferative vs senescent nevus
phases and verified that treatment can be successful in either. Combination with constitutive Tyr-Cre triggered
severe (rare, human-like) neurocutaneous melanosis whereas Dct-Cre induced more typical skin-restricted giant
nevi for which inhibitors of MEK, PI3K, or cKIT induced ~80% regressions whereas combinations fully depleted
visual nevocytes. Topical treatment with the proinflammatory hapten Squaric Acid Dibutyl Ester (SADBE)
induced complete visual regression of CMNs after 3 topical doses over 5 days. This regimen also produced
100% prevention of murine melanoma transformation, but not in untreated nevus skin. Topical SADBE was
found to utilize macrophages (not B/T cells), so it could be tested in human CMN xenografted onto SHO mice
(no B/T cells but contains macrophages) where SADBE recruited murine macrophages and regressed ~90% of
human nevocytes. Since SADBE is already used elsewhere in dermatology, and has been reported to induce
“depigmentation,” we obtained FDA (IND) approval for human testing (FDA required adult testing prior to children)
and also local IRB approval. Aim 1 is a neoadjuvant CMN clinical trial testing topical SADBE or vehicle prior to
elective surgical resection, followed by detailed assessments of nevocyte numbers, oncogene drivers, and
inflammatory cells; Aim 2 uses our models to boldly seek further enhanced efficacy and minimize toxicity through
six strategies: a) dose/schedule optimization of kinase inhibitors and combinations, b) combine MEK inhibitor
(MEKi) with SADBE, as both exhibit individual efficacy; of note, MEKi was recently shown to promote M1-like
over M2-like macrophage polarization, thereby plausibly enhancing SADBE efficacy, c) combine SADBE with
anti-PD1, shown to trigger recruitment of melanocyte targeting T cells, d) combine SADBE with fractional laser
plus anti-PD1 which was recently published to recruit melanocyte-targeted T cells, and e) combine anti-
inflammatory agents and varied dose/schedules to limit cutaneous toxicity while optimizing efficacy.

## Key facts

- **NIH application ID:** 11074204
- **Project number:** 3R01AR072304-07S1
- **Recipient organization:** MASSACHUSETTS GENERAL HOSPITAL
- **Principal Investigator:** DAVID E FISHER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $96,504
- **Award type:** 3
- **Project period:** 2017-08-01 → 2025-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11074204

## Citation

> US National Institutes of Health, RePORTER application 11074204, Therapeutic strategies for treatment of giant congenital melanocytic nevi (3R01AR072304-07S1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/11074204. Licensed CC0.

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