AC Immune Reports Interim Safety Data from Phase 1b/2 ABATE Trial of ACI-24.060 in Down syndrome ACI-24.060 was generally safe and well tolerated in individuals with Down syndrome with no serious adverse ev

AC Immune Reports Interim Safety Data from Phase

1b/2 ABATE Trial of ACI-24.060 in Down syndrome

Lausanne, Switzerland, December 10, 2024

- AC Immune SA (NASDAQ: ACIU), a clinical-stage biopharmaceutical company pioneering precision therapeutics for neurodegenerative

diseases, today announced interim safety and tolerability data from the ABATE Phase 1b/2 trial of ACI-24.060 in individuals living with

Down syndrome (DS). Targeting toxic forms of amyloid beta (Abeta), ACI-24.060 is an active immunotherapy covering Abeta 1-15 (excluding

Abeta T-cell epitopes). The interim analysis was based on data from the first two cohorts of individuals with DS receiving low-dose and

mid-dose ACI-24.060. DS subjects in the interim analysis have been treated for up to one year, with no serious adverse events related

to the study drug and no case of amyloid-related imaging abnormalities (ARIA) observed in this study population.

Dr. Anke Post, Chief Medical Officer of AC Immune

SA, commented: "These interim safety data are encouraging and supportive of the potential of ACI-24.060 to provide people with

Down syndrome a novel therapeutic option targeting brain Abeta pathology while providing initial favorable safety and tolerability."

The ongoing ABATE study (NCT05462106) is a randomized,

double-blind, placebo-controlled Phase 1b/2 trial assessing the safety, tolerability, immunogenicity and pharmacodynamic effects of the

investigational immunotherapy. The study was specifically designed to support parallel development in individuals with prodromal Alzheimer's

disease (AD) and non-demented adults with DS, a vulnerable population predisposed to developing AD.

Dr. Mike Rafii, Medical Director of the

Alzheimer's Therapeutic Research Institute, Professor of Neurology at the Keck School of Medicine, and Coordinating Principal Investigator

of the ABATE study commented: "Safety is particularly important in the Down syndrome population, in which treatments targeting

amyloid pathology are urgently needed to prevent the onset and progression of Alzheimer's disease. To date, the safety and tolerability

profile of ACI-24.060 is encouraging."

ACI-24.060 has received Fast Track designation

from the U.S. FDA for the treatment of AD. The Company previously reported positive interim safety, tolerability, and immunogenicity from

the AD cohorts of the ABATE trial, which supported the treatment with ACI-24.060 in individuals with DS in ABATE.

The trial will now start to evaluate the high dose

of ACI-24.060 in additional patients with DS. Recruitment of individuals with DS continues at ABATE trial sites in the U.S., U.K., and

About the Phase 1b/2 ABATE Study (ClinicalTrials.gov

Identifier: NCT05462106; www.abate-study.com)

The ABATE study is a Phase 1b/2, multicenter, adaptive,

double-blind, randomized, placebo-controlled study to assess the safety, tolerability, immunogenicity, and pharmacodynamic effects of

ACI-24.060 in subjects with prodromal AD and in adults with DS. All participants in the trial must have brain Abeta pathology confirmed

by a positron emission tomography (PET) scan. Recent clinical studies and FDA approvals have validated Abeta as a disease modifying therapeutic

target in AD and are supportive of Abeta PET imaging as a surrogate marker of efficacy. The ABATE trial aims at evaluating various doses/dosing

regimens of ACI-24.060 in both AD and DS populations. Individuals with DS between the ages of 35 and 50 who would like to learn more can

visit the ABATE Study website at www.abate-study.com to find the site nearest them.

About Alzheimer's Disease (AD) in

Individuals with DS have a third copy of all or

part of chromosome 21, which contains the gene that codes for amyloid-precursor protein (APP). Overproduction of APP is believed to cause

the accumulation of Abeta plaques. Virtually all individuals with DS will develop Abeta plaques and AD1, with DS-related AD

sharing a similar pathophysiology and biomarkers with other forms of genetic AD. Given the predictable onset and progression of symptoms

in DS-related AD, AC Immune believes ABATE's results will offer crucial insights into the ability of ACI-24.060 active

immunotherapy to target brain Abeta at its early stages and offer this population a much needed therapeutic option.

ACI-24.060, derived from AC Immune's SupraAntigen platform,

covers Abeta 1-15 which excludes T-cell epitopes. ACI-24.060 has been shown in preclinical studies to induce a strong polyclonal antibody

response that matures and is maintained against both oligomeric and pyroglutamate-Abeta species, key pathological forms of Abeta believed

to drive Abeta plaque formation and disease progression. ACI-24.060 is designed to enhance the formation of broad-spectrum protective

antibodies with the same safety and tolerability previously demonstrated in the ACI-24 program in Phase 1 and 2 trials. This investigational

candidate has the potential to efficiently inhibit plaque formation and increase plaque clearance, and thereby may reduce or prevent disease

AC Immune SA is a clinical-stage biopharmaceutical

company and a global leader in precision prevention for neurodegenerative diseases, including Alzheimer's disease, Parkinson's

disease, and NeuroOrphan indications driven by misfolded proteins. The Company's two clinically validated technology platforms,

SupraAntigen and Morphomer , fuel its broad and diversified pipeline of first- and best-in-class assets, which currently features

sixteen therapeutic and diagnostic programs, including five in Phase 2 development and one in Phase 3. AC Immune has a strong track record

of securing strategic partnerships with leading global pharmaceutical companies, resulting in substantial non-dilutive funding to advance

its proprietary programs and >$4.5 billion in potential milestone payments plus royalties.

SupraAntigen is a registered trademark of

AC Immune SA in the following territories: AU, EU, CH, GB, JP, RU, SG and USA. Morphomer is a registered trademark of AC Immune SA

in CN, CH, GB, JP, KR, NO and RU.

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referenced herein is expressly not incorporated by reference into, and does not constitute a part of, this press release.

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