SAN FRANCISCO –
In the CLARITY AD trial, adverse events (AEs) were common compared with placebo, including amyloid-related edema and effusions; and a recent news report linked a second death to the drug.
Moving forward, “longer trials are warranted to determine the efficacy and safety of lecanemab in early Alzheimer’s disease,” wrote Christopher H. van Dyck, MD, Yale University, New Haven, Conn., and colleagues.
The full trial findings were presented at the Clinical Trials on Alzheimer’s Disease (CTAD) conference, with simultaneous publication on Nov. 29 in the New England Journal of Medicine.
Complications in the field
The phase 3 trial of lecanemab has been closely watched in AD circles, especially considering positive early data released in September and reported by this news organization at that time.
The Food and Drug Administration is expected to make a decision about possible approval of the drug in January 2023. Only one other antiamyloid treatment, the highly controversial and expensive aducanumab (Aduhelm), is currently approved by the FDA.
For the new 18-month, randomized, double-blind CLARITY AD trial, researchers enrolled 1,795 patients aged 50-90 years (average age, 71 years) with early AD. All were randomly assigned to receive either a placebo (n = 898) or intravenous lecanemab, a humanized immunoglobulin G1 (IgG1) monoclonal antibody that selectively targets amyloid beta (A-beta) protofibrils, at 10 mg/kg of body weight every 2 weeks (n = 897).
The study ran from 2019 to 2021. The participants (52% women, 20% non-White) were recruited in North America, Europe, and Asia. Safety data included all participants, and the modified intention-to-treat group included 1,734 participants, with 859 receiving lecanemab and 875 receiving placebo.
The primary endpoint was the Clinical Dementia Rating–Sum of Boxes (CDR-SB). Scores from 0.5 to 6 are signs of early AD, according to the study. The mean baseline score for both groups was 3.2. The adjusted mean change at 18 months was 1.21 for lecanemab versus 1.66 for placebo (difference, –0.45; 95% confidence interval [CI], –0.67 to –0.23; P < .001).
As Dr. van Dyck noted in his presentation at the CTAD meting, this represents a 27% slowing of the decline in the lecanemab group.
The published findings do not speculate about how this difference would affect the day-to-day life of participants who took the drug, although it does refer to “modestly less decline” of cognition/function in the lecanemab group.
Other measurements that suggest cognitive improvements in the lecanemab group versus placebo include the Alzheimer’s Disease Assessment Scale–Cognitive Subscale score (mean difference, –1.44; 95% CI, –2.27 to –0.61), the Alzheimer’s Disease Composite Score (mean difference, –0.05; 95% CI, –.074 to –.027,), and the Alzheimer’s Disease Cooperative Study–Activities of Daily Living Scale for Mild Cognitive Impairment score (mean difference, 2.0; 95% CI, 1.2-2.8; all, P < .001).
Overall, Dr. van Dyck said, “Lecanemab met the primary and secondary endpoints versus placebo at 18 months, with highly significant differences starting at 6 months.”
In a substudy of 698 participants, results showed that amyloid burden fell at a higher rate in the lecanemab group than in the placebo group (difference, –59.1 centiloids; 95% CI, –62.6 to –55.6).
“Lecanemab has high selectivity for soluble aggregated species of A-beta as compared with monomeric amyloid, with moderate selectivity for fibrillar amyloid; this profile is considered to target the most toxic pathologic amyloid species,” the researchers wrote.