Starting on a more gradual dosing schedule of Eli Lilly's Alzheimer's drug Kisunla cut the percentage of patients experiencing potentially serious brain swelling, according to interim results of a late-stage trial presented at a medical meeting on Tuesday.

At week 24 of the year-long study, 14% of patients with early-stage Alzheimer's who received a lower starting dose of the monthly infusion had the brain swelling side effect known as ARIA-E. That compared with 24% of those who received the standard dosing schedule.

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Reduction of toxic amyloid plaques was comparable to those on the standard dose of Kisunla, known by the scientific name donanemab, the company said in a statement.

Lilly said it plans to submit the results to various health regulators for a potential label change modifying the dosing regimen. Kisunla competes with Eisai and Biogen's Leqembi, a similar treatment that also causes brain swelling in some patients.

Kisunla is under review by the European Union's drugs regulator. The body in July rejected Leqembi, saying the risk of serious brain swelling did not outweigh its small impact on slowing cognitive decline.

The UK's Medicines and Healthcare products Regulatory Agency last week approved donanemab, but the country's cost-effectiveness body deemed it too expensive for widespread use within the state-run National Health Service.

Lilly neuroscience chief Anne White would not comment on the European review, but said in an interview that she hopes regulators will "take all of the data we have into consideration and come to a place where they can offer access to patients in Europe."

Interim results of Lilly's 52-week study in 843 people, presented at the Clinical Trials on Alzheimer's Disease conference in Madrid, included four treatment arms. One was the standard monthly dosing used in the pivotal trial that Lilly used to win U.S. approval in July.

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The other three used alternative dosing regimens, including the gradual dosing arm, a separate group in which volunteers received half doses twice a month, and a third group that received the same amount of drug but with a longer pause between doses.

One patient on the gradual dosing arm developed stroke-like symptoms, and died after receiving a clot-busting drug, a known risk for brain hemorrhages in patients on amyloid-lowering drugs. Kisunla carries an FDA warning cautioning against use of the clot buster in those taking the medicine.

All alternate dosing schemes saw some benefit, Dr. Mark Mintun, Lilly's neuroscience group vice president for research and development, said in an interview, but the biggest benefit was in the gradual dosing arm.

In that group, volunteers started with one 350 milligram vial for the first dose, then added in an additional vial at each of the next three monthly infusions.

The standard approved dosing starts with two 350 mg vials for the first three monthly infusions, and then four vials at the fourth and subsequent infusions.

The study's main goal was to document any occurrence of brain swelling.

Patients who saw the most benefit were those with two copies of a genetic variant known as APOE4 - a group that is at higher risk of brain swelling with amyloid-lowering drugs. In these patients, 19% had brain swelling on the gradual dosing regimen, compared with 57% of those on standard dosing.

The dosing change had little impact on the amount of amyloid removed by 24 weeks, with volunteers in the modified group seeing a 67% reduction of plaques on average compared with 69% in the standard dose arm.

Full 52-week results are expected early next year.