Long-term extension data presented at the Alzheimer’s Association International Conference showed amyloid plaque reaccumulation remained slow at up to 2.5 years of follow-up in patients who were taken off of treatment with Eli Lilly’s anti-amyloid antibody.
Eli Lilly’s Alzheimer’s disease therapy Kisunla can remove and keep amyloid plaques away even treatment ends, adding more fuel to the pharma’s conviction that patients can stop treatment with the anti-amyloid antibody once plaques have been cleared from the brain.
Lilly presented long-term extension (LTE) data on Wednesday from its Phase III 7TRAILBLAZER-ALZ 2 study at the 2025 Alzheimer’s Association International Conference in Toronto. The LTE phase enrolled 550 patients who were treated with Kisunla in the main study: some stayed on the anti-amyloid therapy while those who met pre-defined amyloid clearance standards were switched to placebo.
The LTE study also included a parallel group of nearly 660 delayed-start participants who were given placebo in the main trial and switched to Kisunla for this extension phase.
In patients who were taken off Kisunla, “amyloid plaque reaccumulation remained slow” at up to 2.5 years of follow-up. Amyloid plaques reappeared at a rate of 2.4 centilods per year, which John Sims, senior medical director of neurodegeneration at Lilly, told Endpoints News is “so slow that you probably don’t need to get this drug again” once a patient falls below a certain threshold of amyloid in their brain after Kisunla treatment.
Lilly plans to compare the effects of Kisunla in patients who stop treatment after amyloid clearance versus those who continue on with a maintenance schedule of the therapeutic antibody, Sims told Endpoints, though he did not provide details for this study.
Aside from reaccumulation rate, TRAILBLAZER-ALZ 2’s LTE readout on Thursday points to cognitive benefits for Kisunla. Over three years of follow-up, Kisunla was able to slow cognitive decline, as measured by the Clinical Dementia Rating Sum of Boxes tool, versus matched external patients from the Alzheimer’s Disease Neuroimaging Initiative cohort, which tracks cognition in elderly adults who are healthy, have mild cognitive impairment and have early Alzheimer’s disease.
Kisunla’s benefits were more pronounced in patients who start treatment early. Compared with delayed-start counterparts, those who were given the antibody therapy in the main TRAILBLAZER-ALZ 2 study were 27% less likely to progress to the next stage of disease. The LTE data also showed that 75% of patients on Kisunla reached amyloid clearance within 76 weeks of initiation.
Thursday’s data come as Lilly jockeys with Biogen and Eisai for control over the Alzheimer’s disease market. The partners own Leqembi, which was the first anti-amyloid antibody to win the FDA’s full approval, and which beat Kisunla—approved in July 2024—to the market by about a year and a half. But Leqembi has by no means cornered the market: uptake has been slow, though there have been encouraging signs of improvement of late. In the first quarter, Biogen reported approximately $96 million in global sales for Leqembi, while Kisunla made $21 million. Biogen added another $160 million to that number in Q2, while Lilly is set to report second-quarter earnings next week.
