ACIU Stock Price: Over 20% Increase Pre-Market Explanation

By Amit Chowdhry ● Jun 2, 2021
  • The stock price of AC Immune SA (NASDAQ: ACIU) increased by over 20% pre-market. This is why it happened.

The stock price of AC Immune SA (NASDAQ: ACIU) – a clinical-stage biopharmaceutical company pioneering precision medicine for neurodegenerative diseases – increased by over 20% pre-market. Investors appear to be responding positively to AC Immune SA announcing it provided key clinical and preclinical updates for its SupraAntigen-derived liposomal vaccine candidates, which are designed to convey active, long-lasting immunization against pathological forms of amyloid-beta (Abeta). And AC Immune is completing a Phase 2 study of its first clinical candidate, ACI-24, in people with mild Alzheimer’s disease (AD), and is also advancing an optimized ACI-24 formulation — which demonstrates enhanced and sustained immunogenicity in non-human primate studies, particularly against key pathological forms of Abeta such as oligomeric and pyroglutamate Abeta.

Pyroglutamate Abeta (pyroGlu-Abeta) is known as a highly neurotoxic form of Abeta that is N-terminally truncated and post-translationally modified to form pyroglutamate. And extracellular pyroGlu-Abeta is an important target for immunotherapy, as the peptide’s altered biochemical properties make it more prone to aggregate compared to full-length Abeta, and it is a major component of Abeta plaques. Passive immunization with a monoclonal antibody specific for pyroglutamate Abeta demonstrated encouraging clinical results in a recently published Phase 2 clinical study.

In non-human primates, vaccination with the optimized ACI-24 vaccine had generated a strong, conformation-specific antibody response against oligomeric and pyroGlu-Abeta. And a robust boosting effect was also observed, the magnitude of which was substantially greater against pyroGlu-Abeta compared to full-length Abeta (approx. 8-fold vs 4-fold increase, respectively, between the 3rd and 5th injections). 

Epitope mapping studies using sera from immunized cynomolgus monkeys had showed the strongest signals for sites binding to peptides covering N-terminal regions of Abeta located just beyond where cleavage occurs to form pyroGlu-Abeta (amino acids 3-10, 4-11, 5-12). And this further supports the strong response observed against this key pathological variant.

AC Immune had also completed an 18-month interim assessment of safety and tolerability in the Phase 2 study evaluating ACI-24 in patients with mild AD. And confirming earlier interim results, there have been no safety concerns nor evidence for CNS inflammation or ARIA (amyloid-related imaging abnormalities) related to ACI-24 in any subject. AC Immune is going to complete the Phase 2 study with the 24-month analysis on the basis of currently enrolled patients.


“We believe the optimized ACI-24 formulation represents a potential breakthrough in Abeta vaccination, as it elicits a strong immune response against oligomeric and truncated Abeta, the suggested key culprits in the Abeta pathway driving early Alzheimer’s disease. These exciting preclinical results, combined with the encouraging clinical safety and efficacy we have demonstrated to date for our optimized pTau vaccine ACI-35.030 as well as our first anti-Abeta vaccine candidate ACI-24, highlight the strength and versatility of our SupraAntigen®-V platform for delivering safe and long-lasting active immunization against key proteinopathies in neurodegenerative diseases. We are planning to file an Investigational New Drug (IND) application for the optimized ACI-24 formulation by year-end, followed by an accelerated clinical development in Down syndrome-related AD, with start of Phase 2 as early as 2022/23.”

— Prof. Andrea Pfeifer, CEO of AC Immune SA

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