Keytruda (pembrolizumab) is the world's best-selling cancer drug, used across dozens of cancer types. Insurance coverage for Keytruda is generally robust for FDA-approved indications, as cancer drugs fall under medical benefit (Part B for Medicare) when administered in a clinical setting. Out-of-pocket costs depend on whether coverage is under medical or pharmacy benefit.
Key Facts
Check Your Specific Plan's Formulary
Coverage varies by plan. Use our formulary checker tool to look up your exact copay and restrictions.
Open Formulary CheckerSources and standards behind this page
Drug coverage in the United States is governed by published rules rather than by any one insurer's summary, and the sources below are the primary ones. They are linked so a reader can check a claim without taking this page's word for it.
- FDA Orange Book publishes the therapeutic-equivalence ratings that decide whether a generic may be substituted for a brand-name drug.
- FDA generic drug facts sets out what "generic equivalent" means and what a manufacturer must prove.
- CMS prescription drug coverage defines the rules a Medicare drug plan formulary must follow and how it may change mid-year.
- Medicare.gov drug coverage (Part D) states what a Part D plan is required to offer a member.
- CMS prescription drug appeals documents the coverage-determination and exception process when a drug is denied.
This page describes how coverage and formularies work. It is not medical advice, and a reader's own plan documents and prescriber decide what applies to them.
Frequently Asked Questions
Keytruda is usually covered under your medical benefit (not pharmacy) because it is administered by IV infusion in a clinical setting. This means it falls under Part B for Medicare patients, with 80% coverage after the deductible. For commercial plans, it is typically processed through the medical benefit with applicable coinsurance.
Under medical benefit coverage, you typically pay 20% coinsurance after your deductible. For Medicare Part B, this means approximately $2,000 to $2,400 per infusion without supplemental coverage. Medigap plans or employer supplemental coverage can reduce this further. Out-of-pocket maximums on commercial plans also limit total exposure.
Merck offers the Keytruda patient assistance program for uninsured or underinsured patients who meet income criteria. For commercially insured patients, Merck's copay assistance can help reduce out-of-pocket costs. Medicare patients cannot use manufacturer copay cards but may qualify for other financial assistance programs.
Related Resources
- UnitedHealthcare Formulary 2026
- Blue Cross Blue Shield Formulary 2026
- Medicare Part D Formulary 2026
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