Study summary

Donanemab slowed decline, most in people treated earliest

TRAILBLAZER-ALZ 2 · 1,736 people · 18-month results; approved in the US in July 2024

What was tested

Donanemab, an amyloid-removing antibody given by monthly infusion and stopped once amyloid is cleared, against placebo in early symptomatic Alzheimer's.

What they found

• Decline was 35% slower on the trial's main scale in people with low-to-medium tau, and 22% slower across everyone.
• About a quarter of people on donanemab had brain swelling on scans; 6% had symptoms.
• The two approved antibodies used different scales and patients, so their percentages cannot be compared directly.

What it means

Confirms the lecanemab finding with a second drug, and suggests earlier treatment works better.