AC Immune Reports Interim 12-Month Data from Phase 1b/2 ABATE Trial of ACI-24 in Prodromal Alzheimer’s Disease

AC Immune Reports Interim 12-Month Data from Phase 1b/2 ABATE Trial of ACI-24 in Prodromal Alzheimer’s Disease

ACI-24 anti-Abeta active immunotherapy generally safe and well tolerated in first three Alzheimer’s disease (AD) cohorts in ABATE

Anti-Abeta antibody dose-response demonstrated with antibodies detected at all dose levels in cohorts AD1-3

Ongoing AD4 cohort includes additional adjuvant designed to enhance ACI-24 responses

Lausanne, Switzerland, June 30, 2026 -- AC Immune SA (NASDAQ: ACIU), a clinical-stage biopharmaceutical company pioneering precision therapeutics for neurodegenerative diseases, today announced interim data from the first three cohorts (AD1, AD2 & AD3) of 74 patients with prodromal Alzheimer’s disease (AD) in the Phase 1b/2 ABATE trial following 12 months of treatment with ACI-24 anti-amyloid beta (Abeta) active immunotherapy.

In the trial to date, ACI-24 has been generally safe and well tolerated, with no evidence of amyloid-related imaging abnormalities-edema (ARIA-E). Anti-Abeta antibody responses were detected at every dose level with a dose response.

We evaluated enhancing ACI-24 with an additional adjuvant to boost immunogenicity while the ABATE trial was ongoing. This is currently being tested in the recently initiated ABATE Cohort AD4.

Martin Zügel, MD, interim CEO of AC Immune and Chair of the Board of Directors , commented: “The nature of the antibody response observed in ABATE suggests that we should further enhance immunogenicity for more effective plaque removal. Cohort AD4 was initiated to evaluate enhancing ACI-24 with an additional adjuvant.”

About ACI-24 and the ABATE trial

ACI-24 is AC Immune’s anti-Abeta active immunotherapy candidate. ABATE is a randomized, double-blind, placebo-controlled Phase 1b/2 trial of ACI-24 in prodromal AD and in adults with Down syndrome (DS) where recruitment of participants into the third cohort, DS3, has been concluded ( NCT05462106 ). Enrolled patients in the AD cohorts are required to have a diagnosis of prodromal AD: MCI due to AD according to the National Institute on Aging Alzheimer’s Association (NIA-AA) criteria, and a PET scan at screening must be consistent with the presence of amyloid pathology. Following multiple data safety monitoring board (DSMB) reviews, no safety concerns have been raised to date, with no evidence of amyloid-related imaging abnormalities (ARIA), consistent with previous results.

About the Takeda agreement

AC Immune has an exclusive, worldwide option and license agreement with Takeda on anti-Abeta active immunotherapies, including ACI-24. Under the terms of the agreement, AC Immune received an upfront payment of $100 million and a milestone of $12 million on dosing of the first patients in Cohort AD4. AC Immune is eligible to receive an option exercise fee and additional potential development, commercial and sales-based milestones of up to approximately $2.1 billion. Upon commercialization, AC Immune will be entitled to receive tiered double-digit royalties on worldwide net sales. AC Immune is responsible for conducting the ABATE trial. Following the potential option exercise, Takeda would conduct and fund all further clinical development and be responsible for all global regulatory activities as well as worldwide commercialization.

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About AC Immune SA

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 pipeline of first- and best-in-class assets, which currently features a range of therapeutic and diagnostic programs, including candidates in Phase 2 and Phase 3 development. 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 CA, CN, CH, EU, GB, JP, KR, NO, RU and SG.

The information on our website and any other websites referenced herein is expressly not incorporated by reference into, and does not constitute a part of, this press release.

Forward looking statements

This press release contains statements that constitute “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Forward-looking statements are statements other than historical fact and may include statements that address future operating, financial or business performance or AC Immune’s strategies or expectations. In some cases, you can identify these statements by forward-looking words such as “may,” “might,” “will,” “should,” “expects,” “plans,” “anticipates,” “believes,” “estimates,” “predicts,” “projects,” “potential,” “outlook” or “continue,” and other comparable terminology. Forward-looking statements are based on management’s current expectations and beliefs and involve significant risks and uncertainties that could cause actual results, developments and business decisions to differ materially from those contemplated by these statements. These risks and uncertainties include those described under the captions “Item 3. Key Information – Risk Factors” and “Item 5. Operating and Financial Review and Prospects” in AC Immune’s Annual Report on Form 20-F and other filings with the Securities and Exchange Commission. Forward-looking statements speak only as of the date they are made, and AC Immune does not undertake any obligation to update them in light of new information, future developments or otherwise, except as may be required under applicable law. All forward-looking statements are qualified in their entirety by this cautionary statement.

20260630__ACIU ACI-24 ABATE 12 mth interim results