As a result, AC Immune will receive a $12 million milestone payment from Takeda under the partners' exclusive, worldwide option and license agreement for AC Immune's active immunotherapies targeting toxic forms of amyloid beta (Abeta), including ACI-24 for the treatment of Alzheimer's disease (AD).

ABATE is assessing ACI-24 in subjects with prodromal AD and in adults with Down syndrome (DS). AD4 includes subjects with prodromal AD.

Dr. Andrea Pfeifer, CEO of AC Immune SA, said: "This milestone underscores the progress in our Phase 1b/2 ABATE trial of ACI-24. AD4 will build on the encouraging early safety and immunogenicity data to date. It allows further evaluation of the potential of ACI-24 and, more broadly, our precision prevention approach to neurodegenerative diseases, which encompasses a pipeline of active immunotherapies and intracellular-targeted small-molecule therapeutics to intervene at the earliest stages of disease."

ACI-24 is an anti-Abeta active immunotherapy candidate designed to induce a robust antibody response against the toxic forms of Abeta believed to drive plaque formation and AD progression. By inducing plaque clearance and efficiently inhibiting plaque formation in the brain, ACI-24 has the potential to delay or slow AD progression.

ACI-24 is being investigated in the ongoing ABATE randomized, double-blind, placebo-controlled Phase 1b/2 trial to assess its safety, tolerability, immunogenicity and pharmacodynamic effects. Data so far show that ACI-24 is generally safe and well tolerated, and that it has generated anti-Abeta antibody responses at all tested doses.

Cohorts AD1, AD2 and AD3 enrolled a total of 74 patients who received ACI-24 at escalating dose levels. The 12-month data readouts from Cohorts AD1, AD2 and AD3 are expected later in Q2 2026. Cohort AD4 will include an initial group of 36 patients treated for 12 months, with follow-up of 6 months, significantly expanding the safety and biomarker efficacy data set. A subsequent expansion of the AD4 cohort could potentially see the total number of subjects reach approximately 112 patients.

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.

Under the terms of the agreement with Takeda, AC Immune received an upfront payment of $100 million and is eligible to receive an option exercise fee and additional potential development, commercial and sales-based milestones of up to approximately $2.1 billion, if all related milestones are achieved over the course of the agreement. Upon commercialization, AC Immune will be entitled to receive tiered double-digit royalties on worldwide net sales.