Lecanemab slows cognitive decline 27%, donanemab 35%, yet CMS amyloid confirmation and ARIA monitoring gate access for 6.7 million eligible US patients.

Two anti-amyloid monoclonal antibodies now hold full FDA approval for early symptomatic Alzheimer's Disease: lecanemab (Leqembi, Eisai/Biogen, approved July 2023) and donanemab (Kisunla, Eli Lilly, approved July 2024). The CLARITY AD trial showed 27% slowing of cognitive decline on the CDR-SB scale at 18 months for lecanemab; TRAILBLAZER-ALZ 2 showed 35% slowing for donanemab in the combined low-medium tau population. Both agents require confirmed amyloid pathology by PET or CSF testing and are indicated for the mild cognitive impairment or mild dementia stage of disease.

CMS covers lecanemab under Medicare Part B as an administered infusion, conditional on confirmed amyloid pathology and physician-supervised data collection. Amyloid PET coverage under Medicare has historically been limited, with the beta-amyloid PET national coverage determination restricted to once per lifetime for one indication. Blood-based biomarkers, particularly plasma pTau-217, are emerging as lower-cost confirmation tools that could ease that bottleneck. Amyloid-related imaging abnormalities, a class safety effect requiring serial MRI monitoring, add infrastructure cost and constrain which infusion sites can realistically administer either therapy.

Access hinges on amyloid confirmation capacity, not drug efficacy or physician willingness.

Five questions this report answers:

Q1 - What does CMS's Part B policy require for amyloid confirmation and ARIA monitoring before covering lecanemab or donanemab?

Q2 - How do lecanemab and donanemab compare on efficacy, ARIA safety, dosing schedule and annual list price?

Q3 - Which pipeline agents, including remternetug and the oral candidate ALZ-801, could disrupt this market by 2027?

Q4 - Why has Medicare limited amyloid PET coverage to once per lifetime, and can blood biomarkers ease that gate?

Q5 - What sourcing and verification standard backs the drug comparison and payer-coverage figures in this brief?

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Live report page:  https://axlrx.ai/alzheimers-disease/competitive-intelligence/

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Mike || Global Pharma Commercial Marketing Head

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