Developing Story
Posaconazole – Antifungal Repurposing for ALS/TDP-43 Pathology (2026)
A June 2026 preprint identifies posaconazole as a promising repurposed antifungal for reducing TDP-43 pathology in ALS, after ketoconazole was ruled out due to liver toxicity. Posaconazole's existing FDA-approved profile may facilitate accelerated clinical development. The finding is significant for ALS drug development and broader TDP-43 neurodegeneration research.
Importance: 66%Confidence: 70%Mentions: 1Updated: June 7, 2026
## Posaconazole – Antifungal Repurposing for ALS/TDP-43 Pathology (2026)
### Overview
A June 2026 preprint identifies posaconazole, an azole-based antifungal CYP51 inhibitor, as a potentially viable alternative to ketoconazole for reducing TDP-43 pathology relevant to ALS (amyotrophic lateral sclerosis). Ketoconazole had previously demonstrated efficacy but is reportedly not viable for ALS repurposing due to liver toxicity when orally delivered (bioRxiv, June 1, 2026).
### Key Findings
- **Prior work:** Ketoconazole was shown to stabilize TDP-43 native self-interactions, reduce TDP-43 pathology, and rescue TDP-43-induced SREBP2 downregulation (bioRxiv, June 1, 2026)
- **Problem:** Ketoconazole causes liver toxicity when orally administered, blocking ALS repurposing (bioRxiv, June 1, 2026)
- **Approach:** Seven additional azole-based CYP51 inhibitors were tested using established TDP-43 mislocalization and aggregation assays (bioRxiv, June 1, 2026)
- **Finding:** Posaconazole reportedly emerged as an effective candidate (bioRxiv, June 1, 2026)
- **Status:** Preprint; not yet peer-reviewed
### Context
TDP-43 proteinopathy is a hallmark of ALS and frontotemporal dementia (FTD). There are currently very few disease-modifying treatments for ALS. Drug repurposing from approved compounds—particularly those with established safety profiles in other indications—offers a faster path to clinical trials. Posaconazole has an established FDA-approved profile for invasive fungal infections, which may facilitate IND applications.
### Strategic Relevance
For biotech investors and pharma attorneys, the posaconazole-ALS pathway represents a potentially accelerated repurposing opportunity given the compound's existing regulatory history. IP strategy around CYP51 inhibition for neurological indications warrants attention. The TDP-43 target also connects to broader neurodegeneration research (Alzheimer's, FTD) that is attracting significant capital.