# Development of brain-penetrant drugs targeting N. fowleri primary amoebic meningoencephalitis (PAM)

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2024 · $239,563

## Abstract

PROJECT SUMMARY
The free-living amoeba Naegleria fowleri is responsible for severe primary amoebic meningoencephalitis (PAM),
which mostly occurs in healthy children and young adults. N. fowleri is considered as one of the deadliest human
pathogens and is a category B biodefence agent. N. fowleri infection is problematic due to the rapid onset and
destructive nature of the disease as well as the lack of effective treatments. Currently, there is no single. proven.
evidence-based treatment with a high probability of cure. Disruption of sterol biosynthesis in N. fowleri by smallmolecule
inhibitors may be an effective intervention strategy against fatal amoebic meningoencephalitis. In the
preliminary studies, we pharmacologically validated N. fowleri CYP51 (NfCYP51) as a potential therapeutic
target. An intrinsic difficulty in achieving anti-Naegleria effect in vivo is that a drug must cross the blood-brain
barrier (BBB) to reach the site of action. Limited brain permeability of drugs targeting CYP51 in pathogenic fungi
prevents them from being efficacious in the treatment of PAM. The goal of our proposal is to develop brainpenetrant
bona fide CYP51 inhibitors with anti-Naegleria activity and deploy them as the predecessors offuture
anti-PAM therapeutics. To achieve this goal, we assembled an interdisciplinary team of investigators with
expertise in N. fowleri biology (Debnath, Pl), computational chemistry (Brancale, Co-I), and medicinal chemistry
for CNS applications (Ballatore, Co-I). In our preliminary studies, we selected compounds possessing
physicochemical parameters compatible with BBB permeability. We identified small-molecule hits that are
characterized by the presence of a carboxylate ester moiety which, in vivo, is rapidly hydrolyzed. A follow up
study with hydrolytically more stable ether analogs identified two compounds with improved NfCYP51 binding
and potency. The in vivo assessment confirmed detection of these two ether analogs in brain tissue. The primary
objectives of this application are further evaluation of one BBB permeable ether congener for in vivo efficacy and
the design, synthesis, and evaluation of congeners with the carbonyl group isosterically replaced with the 4-
membered ring heterocycles, oxetane, thietane or their derivatives, that render compounds more resistant to
chemical and enzymatic hydrolysis. Studies in Aim 1A include iterative cycles of design and synthesis of the
analogs that, based on our current understanding of the structure-activity and structure-property relationships
(SARISPR), are expected to exhibit both anti-N. fowleri activity and favorable ADME-PK. Studies in Aim 1 B will
validate the newly synthesized compounds in a cascade of in vitro and in vivo assays for physicochemical
properties (pKa, logP, log074), aqueous solubility, hydrolytic stability in buffers and plasma, potency, cytotoxicity,
BBB permeability, metabolic stability and brain and plasma PK. Two compounds satisfying all go-no-go criter...

## Key facts

- **NIH application ID:** 10989460
- **Project number:** 1R21AI171538-01A1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** Anjan Debnath
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $239,563
- **Award type:** 1
- **Project period:** 2024-05-23 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10989460

## Citation

> US National Institutes of Health, RePORTER application 10989460, Development of brain-penetrant drugs targeting N. fowleri primary amoebic meningoencephalitis (PAM) (1R21AI171538-01A1). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10989460. Licensed CC0.

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