PCSK9 Inhibitors, Inclisiran, and the Alzheimer's Drug Pipeline: The Next Wave of High-Cost Chronic Therapies

A 58-year-old employee with established cardiovascular disease and elevated LDL despite maximum statin therapy is prescribed evolocumab. The drug costs $5,850 per year at list price. The following quarter, another employee begins lecanemab for early Alzheimer’s disease confirmed by amyloid PET scan. That drug costs $26,500 per year. Neither employee was identified as high-risk at underwriting. Neither will stop therapy voluntarily. The drugs will appear in claims data every month, every plan year, indefinitely.

These therapies represent a category of cost pressure 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. They are chronic therapies for conditions common in aging workforces: cardiovascular disease and Alzheimer’s. The per-member cost is moderate to high. The eligible population is large. The aggregate impact on a small group plan is a sustained baseline increase that accumulates across members and plan years. Current plan design and stop loss structures were not calibrated for this category.

The Cardiovascular Agents

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PCSK9 inhibitors reduce LDL cholesterol by 50 to 60 percent when added to statin therapy. Three agents are commercially available. Evolocumab (Repatha), manufactured by Amgen, is a monoclonal antibody administered by subcutaneous injection every two weeks or monthly. Alirocumab (Praluent), manufactured by Regeneron and Sanofi, uses the same mechanism and dosing schedule. Inclisiran (Leqvio), manufactured by Novartis, is a small interfering RNA therapy administered by healthcare provider injection twice yearly after two initial loading doses.

The pricing history of PCSK9 inhibitors illustrates how market competition can moderate drug costs over time, even before patent expiration. Both evolocumab and alirocumab launched in 2015 at approximately $14,000 to $14,600 per year. Uptake was slow. Payers imposed aggressive prior authorization requirements. Prescribers faced administrative barriers. In 2018, Amgen cut the list price of evolocumab by 60 percent to $5,850 per year. Regeneron and Sanofi matched with a comparable reduction for alirocumab. Inclisiran prices similarly despite its twice-yearly dosing convenience. In 2025, Amgen introduced a direct-to-patient channel (AmgenNow) offering evolocumab at $239 per month, approximately $2,868 per year, for self-paying patients. The commercial plan cost, after PBM negotiation, typically falls in the $4,500 to $5,850 range per year depending on contract terms.

The clinical evidence supporting PCSK9 inhibitors is strong. The FOURIER trial, published in the New England Journal of Medicine in 2017, demonstrated that evolocumab reduced major adverse cardiovascular events by 15 percent in patients with established atherosclerotic cardiovascular disease. The ODYSSEY Outcomes trial, published in 2018, showed alirocumab reduced the same composite endpoint after acute coronary syndrome. These are add-on therapies for patients whose cardiovascular risk remains elevated despite statins, the backbone of cholesterol management.

The eligible population within a commercial workforce is meaningful. Approximately 6 to 8 percent of adults over 45 have established atherosclerotic cardiovascular disease. Among those, a substantial fraction have LDL above target despite statin therapy. 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 to the claims fund. This is not catastrophic. It is not rare. It is predictable recurring cost, layered onto baseline spending, persisting as long as members remain on therapy.

The Alzheimer’s Drugs

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The anti-amyloid Alzheimer’s therapies represent a different order of cost exposure. Two agents have received full FDA approval. Lecanemab (Leqembi), developed by Eisai and Biogen, received traditional FDA approval in July 2023 for treatment of early Alzheimer’s disease. The annual cost is $26,500. Donanemab (Kisunla), developed by Eli Lilly, received full approval in July 2024 at approximately $32,000 per year, with costs varying based on treatment duration.

Both drugs require confirmation of amyloid pathology before treatment initiation. Confirmation requires either an amyloid PET scan, costing $3,000 to $5,000, or cerebrospinal fluid analysis for amyloid biomarkers. The diagnostic requirement adds upfront cost and limits utilization to patients with confirmed early-stage disease. It also adds specialist infrastructure requirements that may delay access in markets without neurology or imaging capacity.

The clinical benefit is documented but modest. Lecanemab slowed cognitive decline by approximately 27 percent over 18 months compared to placebo in the CLARITY AD trial, published in the New England Journal of Medicine in January 2023. Donanemab slowed decline by approximately 29 percent over 18 months in the TRAILBLAZER-ALZ 2 trial, published in JAMA in 2023. These reductions correspond to approximately 4.5 to 7.5 additional months before reaching the next stage of clinical decline. The treatments do not reverse existing damage. They do not stop progression. They slow it.

The safety profile includes amyloid-related imaging abnormalities (ARIA), a category that encompasses brain swelling and microhemorrhages. In clinical trials, approximately 17 percent of lecanemab recipients and up to 30 percent of donanemab recipients showed ARIA on monitoring MRI. Most cases were asymptomatic or mild. Three deaths in donanemab trials were attributed to ARIA. Carriers of the APOE e4 gene variant, which is present in approximately 25 percent of the general population and a higher proportion of Alzheimer’s patients, face elevated ARIA risk. Regular MRI monitoring is required during treatment, adding cost and logistical complexity.

Medicare coverage has expanded. CMS initially restricted lecanemab coverage to registries and clinical trials. Subsequent policy changes broadened access to allow standard coverage under a registry participation requirement. Private insurance coverage remains inconsistent, with some commercial plans covering the drugs for qualifying patients and others imposing restrictions or declining coverage entirely.

For small group plans, a single member on lecanemab changes plan economics. A 25-person plan with $300,000 in expected annual claims sees lecanemab add nearly 9 percent to total cost. Add the diagnostic PET scan, the required monitoring MRIs, and the infusion facility charges, and the all-in cost for a single Alzheimer’s patient exceeds $30,000 annually. The cost is recurring. The member will remain on therapy for years unless disease progression, adverse effects, or amyloid clearance (in the case of donanemab) prompts discontinuation.

Actuarial Implications for Small Groups

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The combined cost of these therapies on a small group plan with an aging workforce is substantial. Consider a 25-person employer with an average employee age of 48. The workforce includes 12 employees over 50, four over 55, and two over 60. Cardiovascular disease prevalence in this age distribution suggests two to three potential candidates for PCSK9 inhibitor therapy. Early cognitive symptoms warranting Alzheimer’s evaluation affect a smaller number, perhaps one member every three to four years based on age-adjusted incidence.

In a baseline year with no high-cost chronic therapies beyond standard medications, expected annual claims are $300,000. In a year with three members on PCSK9 inhibitors ($5,500 each) and one on lecanemab ($26,500 plus monitoring costs), these four drug regimens add approximately $45,000 to annual claims. Total expected claims rise to $345,000, a 15 percent increase from baseline.

The stop loss architecture responds to this scenario in a specific way. A $75,000 specific attachment point is not breached by any individual therapy; 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. The aggregate attachment point, set at 125 percent of expected claims ($375,000), absorbs part of the increase. But a moderately adverse year across other claims categories could push total claims through the aggregate corridor.

At renewal, the stop loss carrier sees $45,000 in predictable chronic drug spend. The aggregate attachment point will be reset to reflect this new baseline. The employer’s monthly level funded contribution rises. This is not a one-year disruption. It is a permanent increase. The workforce that ages into the demographic at risk for these conditions absorbs the cost increase indefinitely. Each year that the workforce ages, the probability of additional members qualifying for PCSK9 therapy or anti-amyloid treatment increases. The cost trajectory does not plateau.

The New Category

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The argument of this article is that PCSK9 inhibitors, inclisiran, and anti-amyloid Alzheimer’s therapies represent a cost category that does not fit existing plan design categories.

Traditional chronic medications for common conditions cost hundreds to low thousands per year. Statins, antihypertensives, and metformin are priced for mass utilization. Plan design absorbs them as routine pharmacy spend without meaningful impact on stop loss calculations.

Specialty drugs for rare diseases cost tens of thousands to hundreds of thousands per year. Their rarity limits aggregate exposure. Stop loss is designed to protect against them. The probability that any given member needs a $300,000 rare disease therapy is low. When it occurs, specific stop loss absorbs the cost above the attachment point.

The new category sits between these poles. Annual costs of $5,000 to $32,000 per therapy. Prevalence in a meaningful fraction of aging commercial populations. Too expensive to absorb as routine pharmacy spend without budget impact. Too common to treat as catastrophic outliers. Too chronic to benefit from stop loss structures designed for acute high-cost episodes.

The structural mismatch is the point. Stop loss attachment points are calibrated for acute events. A $26,500 drug that recurs year after year eventually costs more than a one-time $100,000 surgical episode. The surgery resolves. The drug continues. Current plan design lacks effective tools for this category. Prior authorization confirms clinical appropriateness but does not reduce cost for members who qualify. Step therapy has limited applicability because these drugs are typically prescribed after first-line agents have failed. Cost sharing shifts expense to members but does not reduce plan liability after members reach the out-of-pocket maximum.

The TPA and stop loss market have not yet developed products specifically calibrated to this new category of chronic high-cost therapy. The cost arrives in small group plans as an unmanaged baseline increase with no standard intervention available beyond absorbing the spend and repricing the plan at renewal.