– Open-label extension study will provide COR388 to patients for an additional 48 weeks

– GAIN Trial to continue as planned following pre-specified DMC safety data review

Cortexyme, Inc. (Nasdaq: CRTX), a clinical stage biopharmaceutical company pioneering a novel disease-modifying therapeutic approach to treat what it believes to be a key underlying cause of Alzheimer’s and other degenerative diseases, today announced it is initiating an open-label extension study in the United States for its Phase 2/3 GAIN Trial of COR388 in subjects with mild to moderate Alzheimer’s disease (AD). Additionally, the GAIN Trial Data Monitoring Committee recently completed its first planned safety review and recommended continuation of the study as planned.

“We are pleased to begin an open-label extension study of COR388 and, in doing so, facilitate the opportunity for subjects in the GAIN Trial to continue to participate in research directed at bringing forward a new potential therapeutic option for Alzheimer’s disease,” said Michael Detke, M.D., Ph.D., Cortexyme’s Chief Medical Officer. “We anticipate that the open-label extension of the GAIN Trial will supply valuable data on the safety and clinical activity of COR388 in a larger population of patients, for a longer period of time, and will allow subjects randomized to placebo in the GAIN Trial the opportunity to experience treatment with COR388.”

The GAIN (GingipAIN Inhibitor for Treatment of Alzheimer’s Disease) Trial is based on a growing body of scientific evidence showing that the pathogen Porphyromonas gingivalis, or P. gingivalis, most commonly associated with chronic periodontal disease, and its secreted proteases called gingipains can infiltrate the brain and cause AD. The randomized, double-blind, placebo-controlled trial is evaluating the efficacy, safety, and tolerability of COR388, Cortexyme’s investigational gingipain inhibitor, in patients with mild to moderate AD. The GAIN Trial has been ongoing since the second quarter of 2019, with top-line results expected in the fourth quarter of 2021.

Upon completing the 48-week placebo-controlled period of the GAIN Trial, participants in the United States may be eligible to enroll in the open-label extension study, where they will receive COR388 for an additional 48 weeks. During the open-label extension study, safety will be monitored and additional assessments including cognitive tests will be performed. In Phase 1a/1b testing, Cortexyme previously reported favorable safety, tolerability and pharmacokinetics as well as positive biomarker results demonstrating positive trends in patients with AD.

For more information on the GAIN Trial, visit www.gaintrial.com.

About Cortexyme, Inc.

Cortexyme (Nasdaq: CRTX) is a clinical stage biopharmaceutical company pioneering a novel, disease-modifying therapeutic approach to treat what it believes to be a key underlying cause of Alzheimer’s disease and other degenerative diseases. Cortexyme is targeting a specific, infectious pathogen found in the brain of Alzheimer’s patients and tied to neurodegeneration and neuroinflammation in animal models. The company’s lead investigational medicine, COR388, is the subject of the GAIN Trial, an ongoing Phase 2/3 clinical study in patients with mild to moderate Alzheimer’s. To learn more about Cortexyme, visit www.cortexyme.com or follow @Cortexyme on Twitter.