SimpLeigh

SimpLeigh BV is developing the first disease-modifying therapy for MT-ATP6-related Leigh Syndrome (LS) — a devastating metabolic disorder affecting roughly 1 in 120,000 children, leading to rapid neurodegeneration, severe disability, and early death. With no approved treatments available, the impact on patients and families is immense, both emotionally and financially.

The company is repurposing sildenafil, a well-known PDE5 inhibitor with an established safety profile. Preclinical studies, translational models, and compassionate use in six patients have shown remarkable benefits — including fewer metabolic crises, improved motor and respiratory function, and extended survival. Supported by global patent protection and Orphan Drug Designation, sildenafil is now being evaluated in a pivotal Phase III clinical trial.

SimpLeigh BV was founded through a collaboration between the SIMPATHIC consortium—including Radboud UMC, Amsterdam UMC, and Charité Berlin—and Social Medicines, a mission-driven pharmaceutical company with extensive experience in drug repurposing. Together, they demonstrate how publicly funded research can deliver affordable treatments for ultra-rare diseases. Looking ahead, SimpLeigh aims to expand its pipeline to address additional neurometabolic and neuromuscular disorders, with four further indications already under investigation.