Pharma spent three decades treating Alzheimer by going after the sticky protein that clogs patients' brains. Now the capital is moving.
Biogen, having watched its amyloid bet aducanumab flop spectacularly, is now pursuing a tau-targeting drug with FDA fast-track status granted in April 2025. Across the field, programs targeting inflammation and other mechanisms are drawing interest that used to go exclusively to amyloid and tau. A meta-analysis published this week by Cochrane, the independent evidence-synthesis organization considered the gold standard for systematic medical reviews, provides the most comprehensive look yet at what all that amyloid investment bought: 17 trials, 20,342 participants, effects well below the threshold for clinical meaningfulness, and a brain swelling and bleeding risk that UK regulators said was not worth the cost to the National Health Service. The review is the soundest scientific confirmation yet of what the field has been quietly acting on for years.
Cochrane's analysis, published April 15 by Nonino et al., covered seven anti-amyloid drugs: aducanumab, bapineuzumab, crenezumab, donanemab, gantenerumab, lecanemab, and solanezumab. The two that won FDA approval, lecanemab and donanemab, did slow disease progression in their pivotal trials. But in the broader pool of 17 trials typically lasting 18 months, the absolute effects on cognitive decline and dementia severity were absent or trivial, falling well below established thresholds for the minimum clinically important difference. Only two of the 17 trials in the review were for the drugs currently on the market; 12 tested compounds that never made it through, and three others were discontinued for other reasons, according to Alzheimer's Society.
Bart De Strooper, director of the UK Dementia Research Institute, said Cochrane's method blurred the picture by pooling drugs that failed for different reasons with the two that changed clinical practice. "By mixing failed drugs with the only antibodies that have actually changed clinical practice, it turns therapeutic progress into statistical noise," he said. John Hardy, also at the institute, offered a different read: successful therapies remove amyloid from the brain, and unsuccessful ones do not, which suggests the mechanism itself is not the failure. Both views agree on the data. They disagree on what it means.
The scientific argument will continue. The capital argument is already decided. Pipeline data from Chemical & Engineering News shows that anti-amyloid and anti-tau programs once made up roughly 70 percent of Alzheimer clinical development, with the remaining 30 percent pursuing alternate pathways. That ratio is shifting. Biogen's BIIB080, an antisense oligonucleotide targeting tau, received FDA fast-track designation in April 2025 and could reach regulators within two years. Anti-inflammation programs are drawing increased interest. The Cochrane authors themselves recommend that future trials move beyond amyloid removal. Their conclusion: targeting amyloid beta is unlikely to produce the cognitive gains patients need. Whether or not they are right about the science, the industry started moving before they published.
NICE rejected both lecanemab and donanemab for NHS use, saying the cost to the health service was not justified despite the drugs slowing disease by four to six months. US and European agencies approved them anyway. NICE, the UK's health-cost arbiter, initially turned down both drugs in 2024. It opened a formal consultation in March 2026 under updated cost-effectiveness thresholds, a process that could yet reverse its decision. That divergence between regulatory approval and cost-effectiveness judgment is itself a signal: the amyloid drugs cleared a scientific bar, even if the bar turned out to be lower than their developers hoped. The question Cochrane raises is not whether the drugs work at all, but whether the field bet on the right mechanism for the right duration in the right patients. The field's answer, in moves rather than words, is that it did not.