PTC857 (also known as utreloxastat) is an orally bioavailable small molecule (a proprietary
cyclohexadiene-dione compound) being developed by PTC Therapeutics (PTC) for the
treatment of neurological diseases characterized by high levels of oxidative stress and
mitochondrial pathology, including amyotrophic lateral sclerosis (ALS). In diseases
characterized by high levels of oxidative stress, reactive oxygen species (ROS) production
outstrips the available supply of glutathione, resulting in depletion of glutathione and ROS-mediated cell injury and cell death. PTC857 functions as an inhibitor of the oxidoreductase
15-lipoxygenase (15-LO) enzyme to reduce oxidative stress and spare reduced glutathione.
This study is intended to assess the efficacy, safety, tolerability, pharmacokinetic (PK), and
biomarker effects of PTC857 in adult male and female subjects diagnosed with ALS.  
The objectives of the study are to evaluate the efficacy, safety, tolerability, PK, and effects on biomarkers of PTC857 therapy in subjects with ALS. The study consists of 4 periods: Screening (8 weeks), Treatment (24 weeks), Long-term treatment extension (28 weeks), and Follow-Up (4 weeks). Currently open to enrollment.  Eligible subject swill be randomized to receive PTC857 250 mg twice a day or matching placebo.