FDA Approves Kisunla for Alzheimer's Treatment

On Tuesday, July 2, 2024, the U.S. Food and Drug Administration approved a new Alzheimer's treatment drug, donanemab, branded as Kisunla. This drug has shown promise in clinical trials, modestly slowing cognitive decline in patients diagnosed with early-stage Alzheimer's disease.

Kisunla, however, comes with considerable safety risks, including potential brain swelling and bleeding. Despite these risks, the results are considered significant for patients needing effective early-stage treatment. Anne White, executive vice president and president of Lilly Neuroscience, emphasized the importance of early intervention with Kisunla, stating that earlier treatment offers the most significant potential benefits. White also highlighted the growing number of people at risk for Alzheimer's and the urgency of providing better treatment options.

Alzheimer's advocates have hailed the approval of Kisunla as a progressive step in treating the disease. Dr. Howard Fillit, Alzheimer's Drug Discovery Foundation's co-founder and chief science officer, pointed out that earlier diagnosis and intervention could significantly slow disease progression, thus giving patients additional time to maintain independence.

Kisunla functions similarly to Leqembi, another Alzheimer's drug approved last year. Both drugs target amyloid protein, linked to Alzheimer's development, and have been shown to slow the progression of dementia by several months. However, there are notable differences: Leqembi is administered bi-weekly, while Kisunla is given once a month via intravenous infusion. Additionally, Kisunla therapy can be discontinued once it has successfully cleared amyloid plaques from the brain, potentially reducing both costs and side effects.

In clinical trials, a significant percentage of patients could stop taking Kisunla after achieving the desired medical outcome. Specifically, 17% of patients discontinued the drug at six months, 47% within a year, and 69% within 18 months. Even after stopping the treatment, patients continued to experience a slowdown in cognitive decline.

However, the high cost of Kisunla—set at $32,000 per year—remains a concern. This is higher than Leqembi's annual cost of $26,000, which continues to be administered after amyloid clearance. Furthermore, about 25% of those treated with Kisunla suffered from brain swelling or bleeding. While most cases were mild, approximately 2% were severe, and these side effects were associated with three patient deaths.

Patients with certain risk factors, such as having more than four microscopic brain bleeds or carrying two copies of the Alzheimer's-related gene variant APOE4, are at higher risk for these adverse effects. This heightened risk presents significant challenges for patient management and treatment decisions.

There is also a broader concern within the medical community regarding the heavy focus on anti-amyloid drugs like Kisunla and Leqembi. Some experts worry this could deter participation in clinical trials for other potentially more effective treatments targeting different aspects of Alzheimer's, such as tau tangles and neuroinflammation.

In summary, while Kisunla's approval marks a significant advancement in Alzheimer's treatment, the drug's high cost and safety concerns necessitate careful consideration. Continued research and development of diverse treatment approaches remain crucial to addressing the complexities of this debilitating disease.