Amylyx Pharmaceuticals, Inc. today presented clinical data from the Phase 2 Trial AMX-8000 (PEGASUS) trial of AMX0035 (sodium phenylbutyrate (PB) and taurursodiol (TURSO; also known as ursodoxicoltaurine) for the treatment of Alzheimer’s disease (AD). PEGASUS was a randomized, double-blind, placebo-controlled multi-center trial assessing the effects of AMX0035 in 95 adults (ages 55-89 years old) with dementia or mild cognitive impairment (MCI) due to AD over 24 weeks of treatment. The trial included people with wide-ranging dementia scores and was designed to identify signals of safety, tolerability, short-term clinical effects, and biomarker changes in people with AD.

AMX0035 met the primary endpoint of safety and tolerability. The 6-month trial was not powered to evaluate differences between groups in efficacy outcomes and no differences were seen in the primary efficacy outcome, a newly developed composite outcome of cognitive, functional, and imaging measures, or secondary efficacy outcomes of cognition, function, and imaging. AMX0035 was observed in this trial to have had a significant impact on multiple biomarkers of interest in AD. In cerebrospinal fluid (CSF), AMX0035 showed significant reduction of tau protein 181 (p<0.001), phosphorylated tau protein (p<0.001), modulation of the amyloid beta 42/40 ratio (p<0.05) and increase of 8-hydroxy-2' -deoxyguanosine (8-OHdG), (p<0.01). Multiple additional CSF analyses are ongoing to analyze further biomarker changes. These data were presented as a poster at the 14^th Clinical Trials on Alzheimer’s Disease (CTAD) conference held in Boston and virtually from November 9-12, 2021.

“Alzheimer’s disease is a devastating disease, and we desperately need new treatments for patients,” said Steven E. Arnold, M.D., Professor and Translational Neurology Head of the Interdisciplinary Brain Center at Massachusetts General Hospital and Harvard Medical School and the PEGASUS trial principal investigator. “I am encouraged about the changes observed on critical biomarkers of Alzheimer’s disease in this initial study. I am excited to continue learning more about this investigational product’s potential in the disease as we analyze further biomarkers and consider longer and larger studies to evaluate effects on cognition. Thank you to all of the participants and families who participated in the PEGASUS program.”

“Alzheimer’s is a relentlessly progressive disease affecting the memories, thoughts and behavior of millions of people worldwide and we are appreciative of everyone who participated in this trial,” said Joshua Cohen, Co-CEO, Director and Co-Founder of Amylyx. “We believe AMX0035, targeting neuronal death, has potential to treat many neurodegeneration diseases, in addition to ALS. This trial provides further biological knowledge about AMX0035 which will help inform future clinical development with the goal of alleviating suffering across many disease areas,” added Justin Klee, Co-CEO, Chairman and Co-Founder of Amylyx.

Presentation Details:

Title: Safety and Biological Activity of a Fixed-Dose Coformulation of Sodium Phenylbutyrate and Taurursodiol (PB/TURSO) for the Treatment of Alzheimer’s Disease: Results From the Phase 2a PEGASUS Study

Poster #: LP15

Posters will be available onsite in the Statler Room with specific “Meet the Presenters” sessions during coffee breaks and lunch throughout the meeting. The poster will also be available on the digital CTAD meeting platform.

About the PEGASUS Trial

PEGASUS (NCT03533257) was a randomized, double-blind, multi-center, placebo-controlled trial evaluating the safety, tolerability and activity of AMX0035 in 95 adults with dementia or late mild cognitive impairment (MCI) due to AD over 24 weeks of treatment. The trial was designed to evaluate tolerability in this patient population while also assessing efficacy measures and diverse, disease-relevant markers to allow for evaluation and correlation of imaging-based markers, neurobiological changes, functional measures, and cognitive outcomes in a broad group of people with AD.

About AMX0035

AMX0035 is an investigational product comprised of two complementary active agents, sodium phenylbutyrate (PB) and taurursodiol (TURSO; also known as ursodoxicoltaurine), which were combined in a co-formulation to reduce neuronal death and dysfunction. AMX0035 is designed to target the endoplasmic reticulum and mitochondrial-dependent neuronal degeneration pathways in ALS and other neurodegenerative diseases.

About Amylyx Pharmaceuticals

Amylyx Pharmaceuticals, Inc. is a pharmaceutical company working on developing a novel therapeutic for amyotrophic lateral sclerosis (ALS), Alzheimer’s disease and other neurodegenerative diseases. For more information, visit www.amylyx.com and follow us on LinkedIn and Twitter.

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