Biogen, Eisai's lecanemab gets Alzheimer's nod, but how successful it will be is uncertain
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The US FDA on Friday granted accelerated approval to Biogen (NASDAQ:BIIB) and Eisai's (OTCPK:ESALY) Leqembi (lecanemab), just the second biologic medicine ever approved for Alzheimer's disease.
The therapy is expected to become available around the week of Jan. 23. It comes with a wholesale cost of $26.5K per year based on twice monthly infusions.
Though the approval is excellent news, it remains to be seen whether Leqembi will be a home run in terms of revenue. After all, the two companies won approval of Aduhelm (aducanumab) in 2021 expecting it to become a blockbuster, only to be beat back by criticism of mediocre efficacy and an April 2022 CMS National Coverage Determination (NCD) to only cover that medication in very rare circumstances.
Indeed, the NCD for Leqembi -- yet to be rendered -- will be critical to its success as the vast majority of those who are eligible for the treatment are Medicare enrollees.
What's more, at the time of the Aduhelm NCD, CMS said that FDA-approved monoclonal antibodies that target amyloid -- the protein in the brain thought to contribute to Alzheimer's -- will only be covered in a clinical trial conducted with regulatory authorization. In order for CMS to cover Leqembi, it would need to adjust this stance.
A full approval for Leqembi could help CMS in its decision on covering Leqembi. Eisai (OTCPK:ESALF) on Friday said it will work quickly to file a supplementary Biologics License Application with data from the phase 3 Clarity AD trial to do so.
Another potential concern is the labeling for Leqembi. The patient population it is indicated for is far narrower than for Aduhelm. For Leqembi, it "should be initiated" in those with mild cognitive impairment and the mild dementia stage of Alzheimer's. 
Of course, doctors are free to prescribe Leqembi to anyone with signs of Alzheimer's no matter what the stage. However, the narrower population in the prescribing information will likely weigh on many medical professionals.
Another concern for doctors considering prescribing Leqembi is the treatment's safety record. The labeling contains a warning to monitor for Amyloid Related Imaging Abnormalities ("ARIA") -- characterized by brain swelling and bleeding -- during the first 14 weeks of treatment.
ARIA was seen in some patients during clinical trials. In addition, in December, lecanemab was linked to a third patient death in a trial.
Jason Karlawish, co-director, Penn Memory Center, Perelman School of Medicine, University of Pennsylvania, said that the presence of the APOE4 gene could not only predict one's risk of brain bleeding, but how effective Leqembi will work as well. Possessing the gene is considered a genetic risk factor for Alzheimer's.
Karlawish noted that data from Leqembi trials indicated that those with the APOE4 gene had more brain bleeds and hemorrhages, and the drug wasn't as effective on them either.
"For individuals making the decision whether to take this drug, I believe, I think, many clinicians like myself feel that APOE4 testing needs to be one of the options to consider whether this the right drug for me â and what are the chances of me benefitting as well as suffering risks," he said.
Wall Street appears bullish on Leqembi's prospects with several analysts expressing confidence on Friday that it will gain a positive NCD.
However, Piper Sandler's Christopher Raymond was not among them. Raymond, who has a neutral rating on Biogen (BIIB), said he is concerned about Leqembi's commercial success amid uncertainty over doctor uptake and the hassle of needing infusions every two weeks.