As a follow-up to our previous article portending the next new drug for Alzheimer’s, the FDA has now given approval under its accelerated approval pathway to the new medication Leqembi (originally known as Lecanemab). This drug was developed to help slow down cognitive decline in those with Mild Cognitive Impairment or the early stages of dementia. The drug has been co-developed by Eisai and Biogen, the maker of the earlier controversial Alzheimer’s drug Aduhelm, which fizzled under a cloud of controversy and extravagant pricing. Leqembi targets the toxic amyloid plaque in the brain associated with Alzheimer’s, and in clinical trials involving 1800 patients for 18 months, it produced a result of slowing down cognitive decline in those taking the drug by about 5 months, as compared to those who took a placebo. The drug will be priced at $26,500 per year, though it is anticipated that once patients are on a maintenance dose, that cost may drop, as less medication may be needed. The manufacturers have also stated that they are developing a Patient Assistance Program to help eligible patients who lack the financial means to access the drug. Leqembi will be given intravenously every 2 weeks and there will be regular brain scanning of those taking it, as there are risks of both brain swelling as well as micro brain bleeds with the medication. 13% of those taking the drug in clinical trials had brain swelling and 17% had small brain bleeds. For a comprehensive overview of this new medication and its availability (insurers and Medicare have yet to determine whether and how they will pay for this), click here.

While Leqembi appears to be a significant advance in the treatment of Alzheimer’s, the actual practical effect of the drug is perhaps less spectacular. As one expert made clear, “Lecanemab is a start and not a cure. It is a modest start, but represents an approach to treatment that we can build upon.” You can see the actual study results upon which the FDA granted its approval here. What now becomes clear is that it’s going to be more important than ever to be able to understand and diagnose Alzheimer’s at its earliest stage, given the importance of starting Leqembi as early as possible. On that front, we previously touched on the challenge of using PET scans to determine the presence of amyloid plaques (and thus Alzheimer’s) in the brain, and the expense and difficulty of accessing such scans. 

On the good news front, it does appear that newer types of diagnostic options are now being tested in labs, utilizing both cerebral spinal fluid and blood to detect the presence of these plaques in the brain. Clearly, given the cost and risks of drugs such as Leqembi, no one would want to initiate treatment without confirming that toxic amyloid plaques do in fact exist in the patient’s brain. So these diagnostic tests, though perhaps not yet ready for use in primary care settings, are becoming closer to reality. For example, a new diagnostic test involving cerebral spinal fluid, manufactured by Roche, was recently approved by the FDA. While this might be a more accessible and cheaper test than PET Scans, it’s still quite invasive and unavailable to most. What might really be a breakthrough is the development of blood tests which can detect toxic amyloid plaques. Several research studies along with private diagnostic companies are developing blood tests that may herald the way for easy and inexpensive determinations of whether someone has amyloid plaques in their brains and would therefore be eligible for early interventions, including Leqembi. For example, a recent study published in the Proceedings of the National Academy of Sciences and funded by the National Institutes of Health reports on the development of a blood test that may detect the presence of amyloid beta years before symptoms appear, thus making early intervention possible. As well, companies like Quest Diagnostics are working toward Alzheimer’s detecting blood tests that, while not yet perfect, may be accurate enough for use with such drugs as Leqembi. Insurers do not routinely cover these tests, however, nor have these blood tests been confirmed for their reliability in more general and diverse patient populations. However, as future treatments for Alzheimer’s come to market, it’s likely that easy, reliable, and inexpensive diagnostic blood testing will need to follow suit.