The European Union’s CHMP said that the benefits of the drug, already approved in the U.S., do not outweigh the risk of potentially fatal brain swelling and bleeding.
Eli Lilly’s Alzheimer’s drug Kisunla has received a negative opinion from the European Union’s drug evaluation board. Meanwhile, competitors Biogen and Eisai are still fighting for market access for rival med Leqembi.
The EU’s Committee for Medicinal Products for Human Use (CHMP) declined Thursday to recommend the monoclonal antibody for approval. The decision was based mostly on safety concerns regarding the drug, which CHMP said were not outweighed by the potential benefits of treatment.
Lilly has 15 days to ask for a re-examination of the opinion. In a statement released Friday, the company said it would do so.
CHMP pointed to the risk of amyloid-related imaging abnormalities (ARIA), a side effect of amyloid-targeting treatments that can signal swelling and bleeding in the brain. In data submitted to support Lilly’s application, ARIA occurred in 36.8% of patients taking Kisunla, compared to 14.9% of patients who received placebo. While most ARIA occurrences don’t cause symptoms, 1.6% of patients did experience “serious ARIA events,” and three patients with ARIA died.
In a standard rating scale that scores Alzheimer’s disease progression, Kisunla showed modest improvements versus placebo, in both patients with and without ApoE4 genes, a risk factor for Alzheimer’s.
Lilly’s main competitor in Alzheimer’s, Biogen and Eisai, have similarly struggled to get rival molecule Leqembi approved in Europe. In July 2024, Leqembi failed to secure recommendation for approval from CHMP, but the companies asked for a re-examination. In November 2024, CHMP reversed course and backed approval for Leqembi, but only in patients with one or no copies of the ApoE4 gene. In January 2025, however, the full European Commission asked the CHMP to reconsider based on new safety data. Earlier this month, CHMP reiterated its positive stance on Leqembi.
In a note to investors Friday, William Blair analysts said they “view the CHMP’s negative opinion on Kisunla as unsurprising, given the initial negative opinion for Leqembi.” The analysts also wrote that reexaminations result in CHMP reversing itself about 25% of the time, including in Leqembi’s case. However, the analysts concluded that “there is real risk here that Kisunla may not make it over the line in the EU,” given the rates of ARIA reported in Lilly’s data.
Kisunla received FDA approval in the U.S. in July 2024. In Phase III trials used to support that approval, ARIA with microhemorrhages occurred in about 31.4% of patients. In October 2024, Lilly unveiled new Phase IIIb data showing that while it could not eliminate the adverse event, modified dosing regimens could lower the rates of ARIA and brain swelling. Lilly said it would use that data to apply for an updated label.
Uptake of both Leqembi and Kisunla has been slow as physicians and health systems adjust to the new treatment paradigm. Sales figures reported by Jefferies in February 2025 showed that Leqembi’s U.S sales were essentially flat with about $18.9 million for the previous month, while Kisunla got $4.7 million for the same time period, a jump from $3.2 million.
