How CAD106 works
CAD106 is designed to stimulate the production of antibodies against beta-amyloid while avoiding an immune response against the recipient’s cells and tissues (called an autoimmune response). Beta-amyloids are protein pieces that clump together, forming plaques that are thought to be harmful to nerve cells.
CAD106 is composed of a short fragment of beta-amyloid, which includes only the first six amino acids (amino acids are the building blocks of proteins). It is hoped that the antibody response triggered by the vaccine will break down beta-amyloid plaques in a patient’s brain and prevent new plaques from forming.
Preclinical evidence gathered in animal studies suggests that CAD106 can reduce beta-amyloid accumulation in the brain by inducing antibodies that interfere with beta-amyloid deposits and by binding to beta-amyloid aggregates.
CAD106 in clinical trials
Two Phase 2 randomized and placebo-controlled clinical trials of CAD106 (NCT00733863 in Europe, and NCT00795418 in the U.S, both sponsored by Novartis) were initiated in 2008, and their open-label extension studies (NCT00956410 and NCT01023685) lasted through to 2011 and 2012, respectively.
The main purpose of these trials was to assess the safety and tolerability of multiple doses of subcutaneous (below the skin) injections of CAD106 and to measure the level of the antibody response it generated against beta-amyloid. Results showed that the vaccine was generally safe, well-tolerated, and triggered antibody responses to beta-amyloid in 63.8 percent of those treated with no evidence of autoimmune reactions. However, no differences were seen between the treatment and placebo groups on cognitive decline and brain volume.
A Phase 2/3 clinical trial (NCT02565511), called the Generation Study, is currently underway. It is no longer recruiting patients but research is still ongoing. The study was designed to separately test if CAD106 and another investigative medication, CNP520 from Amgen, can prevent Alzheimer’s in people, ages 60 to 75, who are cognitively healthy but have two APOE4 genes. APOE4 is a variant of the APOE gene found in a number of Alzheimer’s patients. People with two copies of the APOE4 gene variant are considered to be at high risk of developing mild cognitive impairment (MCI) and/or dementia due to Alzheimer’s disease. MCI is a slight decline in cognitive ability, including thinking and memory skills.
One part of the study was to compare 430 participants given CAD106 as an intramuscular (inside the muscle) injection to 260 individuals receiving a placebo; another part was to compare 390 people treated with oral CNP520 against 260 participants receiving a placebo. The study was going to follow participants for at least 60 months (5 years) and up to 96 months (8 years).
After a pre-planned review of patient data, the study sponsors found that patients taking CNP520 showed a decline in some cognitive scores and decided to discontinue that drug’s portion of the trial. The CAD106 portion of the study is still ongoing, however, and is expected to conclude in March 2025.
The effects of the therapy on cognition, global clinical status, and underlying pathology will be assessed. Primary endpoints are time to diagnosis of MCI or dementia due to Alzheimer’s, and changes in the Alzheimer’s prevention initiative composite cognitive (APCC) test scores at 60 months after treatment start. The APCC test is considered a sensitive tool to detect and track cognitive decline in individuals at risk for progression to stages of Alzheimer’s.
Secondary outcome measures include changes in cognition, biomarkers of disease progression, and antibody response to beta-amyloid.
Last updated: Aug. 20, 2019
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