Executive Summary: PCSK9 Inhibitors, Inclisiran, and the Alzheimer's Drug Pipeline: The Next Wave of High-Cost Chronic Therapies
LFP-09.04 — The Cost Drivers#
PCSK9 inhibitors and anti-amyloid Alzheimer’s therapies represent a cost category that does not fit the existing framework for small group plan design. They are not specialty drugs for rare diseases, where low probability limits aggregate exposure and stop loss is calibrated to absorb the hit. They are chronic therapies for conditions common in aging workforces, priced too high to treat as routine pharmacy spend and too prevalent to treat as catastrophic outliers.
Evolocumab (Repatha) and alirocumab (Praluent) each cost $5,850 per year following 2018 price reductions from their original $14,000 to $14,600 launch pricing. Inclisiran (Leqvio) prices similarly despite twice-yearly provider-administered dosing. The clinical evidence is strong: the FOURIER trial published in the New England Journal of Medicine in 2017 demonstrated a 15 percent reduction in major adverse cardiovascular events for evolocumab versus placebo in patients with established atherosclerotic cardiovascular disease. For a 30-person employer with an average age above 45, three to five members may meet clinical criteria for PCSK9 inhibitor therapy. Three members on PCSK9 inhibitors at $5,500 each add $16,500 annually: not catastrophic, not rare, and persistent indefinitely.
Lecanemab (Leqembi) received traditional FDA approval in July 2023 at $26,500 per year. Donanemab (Kisunla) received full approval in July 2024 at approximately $32,000 per year. Both require confirmation of amyloid pathology through a PET scan costing $3,000 to $5,000 or cerebrospinal fluid analysis, plus regular MRI monitoring for amyloid-related imaging abnormalities. The clinical benefit is documented but modest: lecanemab slowed cognitive decline by 27 percent over 18 months in the CLARITY AD trial; donanemab slowed it by 29 percent over the same period. These represent approximately 4.5 to 7 additional months before the next stage of clinical decline. A single member on lecanemab in a 25-person plan adds nearly 9 percent to total expected annual claims, recurring year over year.
The structural mismatch is the central point. A $75,000 specific stop loss attachment point is not breached by any individual therapy in this category. Lecanemab at $26,500 plus monitoring falls well below the specific deductible. These costs do not trigger specific stop loss. They erode the claims fund from within, quietly, year after year. Prior authorization confirms clinical appropriateness but does not reduce cost for qualifying members. Step therapy has limited application because these drugs are prescribed after first-line agents have failed. The current stop loss and plan design architecture has no effective tool for managing this category.
The TPA and stop loss market have not developed products specifically calibrated to chronic moderate-cost therapies in aging workforces. Plans absorb the spend and reprice at renewal. Each year the workforce ages, the probability of additional members qualifying for PCSK9 or anti-amyloid therapy grows. The cost trajectory does not plateau.