New FDA Approvals: Donanemab for Early Alzheimer's Treatment

The U.S. Food and Drug Administration (FDA) has officially approved donanemab, marketed under the brand name Kisunla, for the treatment of early symptomatic Alzheimer’s disease. Developed by Eli Lilly, this approval marks a significant shift in how clinicians manage the condition. Unlike treatments that only manage symptoms, Kisunla attacks the underlying biology of the disease. This guide breaks down the efficacy, safety profile, and financial realities of this new therapy.

Understanding How Kisunla Works

Kisunla (donanemab-azbt) represents a class of drugs known as amyloid-targeting therapies. In the brains of Alzheimer’s patients, a protein called amyloid-beta clumps together to form plaques. These plaques are believed to disrupt cell function and lead to cognitive decline.

Kisunla is a monoclonal antibody administered via intravenous (IV) infusion. It directs the body’s immune system to clear these sticky plaques from the brain.

The “Stop-Therapy” Distinction

One of the most distinct features of Kisunla compared to its primary competitor, Leqembi (lecanemab), is the duration of treatment. In clinical trials, patients stopped taking the drug once their amyloid plaques were cleared to minimal levels.

  • Finite Treatment: Once scans confirm the plaques are gone, the infusions stop.
  • Reduced Burden: This approach potentially lowers the long-term cost and reduces the number of hospital visits required for infusions.
  • Trial Data: In the Phase 3 study, approximately 17% of patients were able to stop treatment after six months, and 47% stopped after one year because the plaques had been successfully cleared.

Efficacy: Results from the TRAILBLAZER-ALZ 2 Trial

The FDA approval was largely based on data from the TRAILBLAZER-ALZ 2 Phase 3 study. This trial involved 1,736 participants with early symptomatic Alzheimer’s disease. Researchers measured effectiveness using the Integrated Alzheimer’s Disease Rating Scale (iADRS), which assesses a patient’s ability to think clearly and perform daily tasks.

Key Findings

  • Slowing Decline: Among participants with low-to-medium levels of tau (another protein associated with Alzheimer’s), Kisunla slowed cognitive decline by 35% compared to a placebo over 18 months.
  • Daily Function: Patients retained their ability to perform daily activities, such as handling finances or driving, for longer periods compared to those who did not receive the drug.
  • Total Population: When looking at the entire study population (including those with higher levels of tau protein), the drug slowed decline by 22%.

It is important to note that Kisunla is not a cure. It does not reverse memory loss that has already occurred. However, it significantly delays the progression from mild impairment to more severe stages of dementia.

Safety Profile and Side Effects

While the efficacy data is promising, Kisunla comes with serious safety considerations. The FDA has included a Boxed Warning regarding Amyloid-Related Imaging Abnormalities (ARIA). This is a known side effect of antibodies that target amyloid plaques.

ARIA-E and ARIA-H

There are two primary types of ARIA that patients and caregivers must monitor:

  1. ARIA-E (Edema): This involves swelling in areas of the brain. In the clinical trials, this occurred in roughly 24% of participants taking Kisunla. Most cases were asymptomatic and resolved on their own, but severe cases can occur.
  2. ARIA-H (Hemorrhage): This refers to small spots of bleeding in or on the surface of the brain. This occurred in 31% of the treated group compared to about 13% in the placebo group.

Monitoring Requirements

Because of these risks, patients prescribing Kisunla must undergo regular MRI scans to monitor for brain swelling or bleeding. These scans are typically required before the 2nd, 3rd, and 4th infusions. If ARIA is detected, treatment may need to be paused or permanently discontinued depending on severity.

Eligibility: Who Qualifies for Kisunla?

Kisunla is not approved for everyone with Alzheimer’s. It is specifically indicated for patients with early symptomatic Alzheimer’s disease. This includes people with:

  • Mild cognitive impairment (MCI).
  • Mild dementia stage of disease.

Diagnostic Confirmation

Before a doctor can prescribe Kisunla, they must confirm the presence of amyloid pathology. This is typically done through:

  • PET Scans: Brain imaging that visualizes amyloid plaques.
  • Lumbar Puncture: A spinal tap to test cerebrospinal fluid for amyloid markers.

Patients with advanced Alzheimer’s or those without confirmed amyloid buildup are not eligible for this treatment.

Cost and Insurance Coverage

Eli Lilly has set the list price for Kisunla at $32,000 for a 12-month course of therapy. This is slightly higher than the annual price of Leqembi ($26,500). However, the total cost of Kisunla may end up being lower for many patients because treatment can be stopped once plaques are cleared.

Medicare Coverage

The Centers for Medicare & Medicaid Services (CMS) has stated that they will cover drugs like Kisunla under specific conditions:

  1. The FDA grants traditional approval (which Kisunla has received).
  2. The patient and provider participate in a registry to collect real-world evidence.

For Medicare patients, the standard Part B coverage applies. This usually means Medicare pays 80% of the cost after the annual deductible is met, leaving the patient responsible for the remaining 20%. This 20% co-insurance can be substantial (over $6,000 per year), though many patients have Medigap or supplemental insurance plans that may cover these out-of-pocket costs.

Frequently Asked Questions

How is Kisunla administered?

Kisunla is given as an intravenous (IV) infusion once every four weeks. The infusion typically takes about 30 minutes.

Does Kisunla restore memory?

No. Kisunla does not restore lost memories or reverse cognitive damage. Its function is to slow down the rate at which the disease gets worse, giving patients more time with functional independence.

How does Kisunla differ from Leqembi?

Both drugs target amyloid plaques, but they have differences. Leqembi is administered every two weeks, while Kisunla is administered once a month. Furthermore, Leqembi is typically taken indefinitely, whereas Kisunla is designed to be stopped once the amyloid plaques are cleared from the brain.

Are there genetic risks associated with taking Kisunla?

Yes. Patients with the APOE4 gene specifically homozygotes (those with two copies of the gene) have a higher risk of developing serious side effects like ARIA. Genetic testing is often recommended before starting treatment to assess this risk.