Press Release

--Independent data monitoring committee (IDMC) determined the trial unlikely to meet primary endpoint – 

--Alector remains focused on advancing its pipeline of novel ABC-enabled candidates, including an anti-Aβ antibody for Alzheimer’s disease (AD), a GCase enzyme replacement therapy (ERT) for Parkinson’s disease (PD), a tau siRNA for AD, an α-synuclein siRNA for PD, and an NLRP3 siRNA for multiple neurological and metabolic disorders, alongside several first-in-class discovery programs—

SOUTH SAN FRANCISCO, Calif., April 29, 2026 (GLOBE NEWSWIRE) -- Alector, Inc. (Nasdaq: ALEC), a biotechnology company focused on developing therapies to counteract the devastating progression of neurodegeneration, today confirmed that the Phase 2 PROGRESS-AD trial of nivisnebart (AL101/GSK4527226) in individuals with early Alzheimer’s disease (AD) will be discontinued. The decision follows a pre-specified futility analysis conducted by an IDMC, which concluded that the trial was unlikely to meet its primary endpoint of slowing disease progression at completion.

“This outcome is disappointing for patients and families affected by Alzheimer’s disease and underscores the complexity of developing effective treatments for this devastating disease,” said Arnon Rosenthal, Ph.D., Chief Executive Officer of Alector. “We are deeply grateful to the patients, caregivers, investigators and study staff who participated in the PROGRESS-AD trial and contributed to advancing the scientific understanding of progranulin biology in neurodegeneration. We remain committed to progressing our broader pipeline of programs targeting neurodegenerative disease, including multiple wholly owned candidates enabled by our ABC platform.”

Alector and GSK have been co-developing nivisnebart. The companies will work closely with study investigators to inform participants enrolled in the PROGRESS-AD trial. Full results will be shared at a future medical meeting or congress.

Alector Pipeline Outlook
Alector remains focused on advancing a pipeline of programs designed to treat neurodegenerative diseases through mechanisms that remove toxic proteins, replace deficient proteins, and restore immune and neuronal function. A key pillar of this strategy is Alector Brain Carrier (ABC), the company’s proprietary blood-brain barrier technology platform, which has been developed over the last seven years to enhance brain delivery and enable peripheral dosing across multiple modalities, including antibodies, enzymes, and siRNA.

Alector continues to advance AL037/AL137, its ABC-enabled anti-amyloid beta antibody program for the treatment of Alzheimer’s disease, through investigational new drug (IND)-enabling studies, and is targeting an IND submission in Q1 2027. AL037/AL137 is engineered for robust brain uptake, potency, and safety, incorporating ABC with tuned transferrin receptor binding to facilitate brain penetration and plaque removal while minimizing hematologic effects.

In addition, Alector is advancing its ABC-enabled siRNA platform, which is designed to allow peripheral dosing and potentially more convenient administration compared with traditional intrathecal delivery. AL064/AL164, an ABC-enabled tau-targeting siRNA for Alzheimer’s disease and other tauopathies, is progressing towards IND-enabling studies, while other siRNA programs, ADP062-ABC (alpha synuclein) and ADP065-ABC (NLRP3), continue to move toward lead selection.

The company is also progressing AL050, its ABC-enabled engineered glucocerebrosidase enzyme replacement therapy for Parkinson’s disease, toward an IND application targeted for 2027.

About AL101 / GSK4527226
AL101/GSK4527226 is an investigational human monoclonal antibody designed to block and downregulate the sortilin receptor to elevate progranulin (PGRN) levels in the brain. PGRN, a protein encoded by the GRN gene, regulates lysosomal function, neuronal survival, and inflammation. The protein is genetically linked to multiple neurodegenerative disorders. Alector and GSK have been co-developing AL101 for the potential treatment of early Alzheimer’s disease (AD).

About Alector
Alector is a biotechnology company focused on developing therapies to counteract the devastating progression of neurodegenerative diseases. Leveraging the principles of genetics, immunology, and neuroscience, the company is advancing a portfolio of programs that aim to remove toxic proteins, replace missing proteins, and restore immune and nerve cell function. Supported by biomarkers, Alector’s product candidates seek to treat a range of indications, such as Alzheimer’s disease and Parkinson's disease. The company is also developing Alector Brain Carrier (ABC), a proprietary blood-brain barrier platform, which is being applied to its preclinical and research pipeline. ABC aims to enhance the delivery of therapeutics, achieve deeper brain penetration and efficacy at lower doses, and ultimately improve patient outcomes while reducing costs. Alector is headquartered in South San Francisco, California. For more information, please visit www.alector.com.

Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements in this press release include, but are not limited to, statements regarding our business plans, business strategy, product candidates, research and preclinical pipeline, blood-brain barrier technology platform, planned and ongoing preclinical studies, expected milestones, and expectations of our collaborations. Such statements are subject to numerous risks and uncertainties, including but not limited to risks and uncertainties as set forth in Alector’s Annual Reports on Form 10-K and Quarterly Reports on Form 10-Q, with the Securities and Exchange Commission (“SEC”), as well as the other documents Alector files from time to time with the SEC. These documents contain and identify important factors that could cause the actual results for Alector to differ materially from those contained in Alector’s forward-looking statements. Any forward-looking statements contained in this press release speak only as of the date hereof, and Alector specifically disclaims any obligation to update any forward-looking statement, except as required by law.

Alector Contacts:
Argot Partners (media)
David Rosen
(646) 461-6387
alector@argotpartners.com

Argot Partners (investors)
Laura Perry
(212) 600-1902
alector@argotpartners.com

Source: Alector, Inc.