Shionogi has enrolled the first patients in its global Phase II clinical trial, Esprit, assessing the investigational drug S-606001 in adults with late-onset Pompe disease (LOPD).
The randomised, multi-centre, double-blind, placebo-controlled trial will enrol participants across the European Union, the UK, and the US.
This 52-week trial will examine the pharmacodynamics, preliminary efficacy, and safety of S-606001 as an oral substrate reduction therapy (SRT), used alongside standard enzyme replacement therapy (ERT) in adults with confirmed LOPD.
Pompe disease is a rare genetic metabolic disorder, affecting both children and adults. It is caused by a deficiency of acid alpha-glucosidase (GAA), leading to abnormal glycogen accumulation in tissues, especially muscle.
S-606001 is an investigational SRT thought to reduce glycogen accumulation in muscle lysosomes by blocking glycogen synthase (GYS1). ERT increases GAA enzyme levels to promote glycogen breakdown while SRT aims to reduce glycogen production.
By targeting different aspects of glycogen metabolism, SRT may be used alone or with ERT.
Shionogi's chief medical officer Juan Carlos Gomez said: “Currently, ERTs are the standard of care for LOPD, but their efficacy can wane over time, leading to continued decline in skeletal muscle function.
“There is a significant unmet need for new treatment approaches that can be complementary to existing treatments to further slow disease progression.”
In 2024, Shionogi obtained exclusive global rights to S-606001 from Maze Therapeutics. The compound received the US Food and Drug Administration (FDA) rare paediatric disease designation in 2025 and orphan drug designation in 2022. S-606001’s safety and effectiveness have not been established.
In January 2025, Shionogi’s oral antiviral for respiratory syncytial virus (RSV) met its primary endpoint in a Phase II study. Some participants achieved an 88.94% reduction in viral load.
