Eli Lilly & Co. has recently applied for full approval of its Alzheimer's disease drug in the United States. The drug, known as donanemab, is expected to compete with Eisai Co.'s Leqembi in the market. Donanemab has shown promising results in removing a toxic protein called amyloid from the brains of early Alzheimer's patients, making it the second drug to do so after Leqembi received full approval on July 6.
Lilly revealed the details of a final-stage trial at a conference in Amsterdam, where more than 1,700 patients with early-stage Alzheimer's disease or mild cognitive impairment were involved. The trial lasted for 18 months, with participants receiving either donanemab or a placebo. The results showed that donanemab slowed the progression of cognitive and functional decline by 22% on one composite scale and 29% on a similar measure compared to the placebo.
In May, Lilly had already announced the success of the trial. However, the full results, which were presented at the Alzheimer's Association International Conference, demonstrated that the drug had stronger effects on patients with low to moderate levels of another Alzheimer's-linked brain protein called tau. In this group, the medicine reduced the progression of the disease by about 35% compared to the placebo.
While the potential benefits of donanemab are significant, there are important side effects associated with its administration. The monthly infusion has been linked to swelling and bleeding in the brain, affecting more than 36% of the trial recipients. Although most cases were asymptomatic, 6% of the patients experienced symptoms such as headache or confusion, and three patients with brain swelling or bleeding sadly died.
Despite the side effects, experts believe that the positive data from the trial make it highly likely that donanemab will receive FDA approval. Eric Widera, a geriatrician from the University of California, San Francisco, stated that the results show a slight improvement in patients taking donanemab. However, there are concerns about the real-world implementation of the drug due to the complicated administration and the need for careful monitoring of potential side effects.
The head-to-head competition between donanemab and Leqembi in the Alzheimer's drug market is still ongoing. Both drugs have their advantages and disadvantages, with donanemab requiring infusion every four weeks compared to Leqembi, which is infused every two weeks. Additionally, the rates of brain swelling observed in Lilly's trial were slightly higher than those seen with Leqembi.
As the future of these drugs unfolds, doctors and patients will have to carefully consider the pros and cons of each option. David Knopman, a neurologist at the Mayo Clinic, mentioned that he doesn't have a clear choice yet and will leave the decision up to the families. With the potential for billions of dollars in the market, the ultimate goal is to find drugs that can effectively treat Alzheimer's and pave the way for even more advanced and powerful treatments in the future.