AC Immune publishes Phase 1b/2a trial results of ACI-35.030 in eBioMedicine.

• AC Immune publishes Phase 1b/2a trial results in eBioMedicine • ACI-35.030 generates rapid polyclonal response against pathological Tau • JACI-35.054 induces differential antibody response in early Alzheimer’s patients • No clinically relevant safety and tolerability observations • ACI-35.030 advances to Phase 2b ReTain clinical trial in preclinical Alzheimer’s disease.

Lausanne, Switzerland, September 12, 2025 — AC Immune SA (NASDAQ: ACIU), a clinical-stage biopharmaceutical company pioneering precision therapeutics for neurodegenerative diseases, has published peer-reviewed results from the Phase 1b/2a trial of its anti-pTau active immunotherapy, ACI-35.030, in the journal eBioMedicine Peer-reviewed results from Phase 1b/2a Trial of Anti-pTau Active Immunotherapy from AC Immune Published in eBioMedicine^[1]. The study, conducted in collaboration with Janssen Pharmaceuticals, Inc., a Johnson & Johnson company, evaluated two formulations of the immunotherapy, ACI-35.030 and JACI-35.054, in early Alzheimer's disease patients.

The key findings of the trial, which compared the two formulations, showed that ACI-35.030, developed using AC Immune's SupraAntigen® technology, generated a rapid and potent polyclonal response against pathological forms of Tau after a single dose. The treatment maintained response rates of 94-100% through week 74 in high-dose cohorts, with no clinically relevant safety concerns Peer-reviewed results from Phase 1b/2a Trial of Anti-pTau Active Immunotherapy from AC Immune Published in eBioMedicine^[1]. In contrast, JACI-35.054 induced a differential antibody response in early Alzheimer's patients Peer-reviewed results from Phase 1b/2a Trial of Anti-pTau Active Immunotherapy from AC Immune Published in eBioMedicine^[2].

Based on these positive results, ACI-35.030 has advanced to the Phase 2b ReTain clinical trial, which is expected to enroll approximately 500 participants with preclinical Alzheimer's disease. The Phase 2b ReTain trial is a potentially registration-enabling randomized, multicenter, double-blind, placebo-controlled study designed to test the hypothesis that ACI-35.030 can delay or prevent the onset of cognitive impairment in individuals with preclinical AD Peer-reviewed results from Phase 1b/2a Trial of Anti-pTau Active Immunotherapy from AC Immune Published in eBioMedicine^[1].

The primary endpoint of the ReTain trial will measure cognitive decline as assessed by the Preclinical AD Cognitive Composite 5 (PACC-5) score, while the key secondary efficacy endpoint will assess the effect of ACI-35.030 on the propagation and/or accumulation of Tau pathology compared to placebo, as measured by Tau PET imaging Peer-reviewed results from Phase 1b/2a Trial of Anti-pTau Active Immunotherapy from AC Immune Published in eBioMedicine^[1].

The ReTain trial is fully funded and conducted by Janssen Pharmaceuticals, Inc., and is currently being conducted at more than 40 clinical trial sites in the U.S., Japan, UK, and Australia, with more sites expected to open shortly Peer-reviewed results from Phase 1b/2a Trial of Anti-pTau Active Immunotherapy from AC Immune Published in eBioMedicine^[1].

AC Immune's CEO, Dr. Andrea Pfeifer, commented on the results, stating, "These data show that ACI-35.030 (JNJ-2056) was well tolerated at all tested doses and induced a rapid and sustained response against pathological Tau, while requiring less frequent dosing to maintain titers as compared to monoclonal antibodies. Safety and rapid, durable responses are key advantages of active immunotherapies, which make them particularly well suited to the long-term treatment needed to achieve precision prevention. ACI-35.030 is continuing to progress according to plan in the Phase 2b ReTain trial, being conducted by our development partner Johnson & Johnson." Peer-reviewed results from Phase 1b/2a Trial of Anti-pTau Active Immunotherapy from AC Immune Published in eBioMedicine^[1]