ACI-24 (anti-Abeta vaccine) - (ABATE)

April 30, 2026: AC Immune SA (NASDAQ: ACIU) announced dosing of the first patients in Cohort AD4 (prodromal Alzheimer’s disease) in its ongoing randomized, double-blind, placebo-controlled Phase 1b/2 ABATE trial evaluating ACI-24, an anti-amyloid beta (Abeta) active immunotherapy. Initiation of AD4 triggered a $12 million milestone payment to AC Immune from Takeda under their exclusive worldwide option and license agreement for AC Immune’s active immunotherapies targeting toxic Abeta forms.

ABATE is assessing ACI-24 in subjects with prodromal AD and in adults with Down syndrome. The trial is evaluating safety, tolerability, immunogenicity, and pharmacodynamic effects (NCT05462106). AC Immune reported that, to date, ACI-24 has been generally safe and well tolerated and has generated anti-Abeta antibody responses at all tested doses; DSMB reviews have raised no safety concerns.

Cohorts AD1–AD3 enrolled 74 patients at escalating doses; 12-month data readouts from these cohorts are expected later in Q2 2026. Cohort AD4 starts with 36 patients treated for 12 months plus 6 months follow-up, with a potential expansion to ~112 total subjects.