When Does Keytruda Patent Expire?

The earliest patent in the Keytruda portfolio has already lapsed (2025), so generic or biosimilar competitors are legally clear to enter the market for that specific composition or method. Later patents extending to 2040 may still cover specific formulations, dosing regimens, or manufacturing processes — these "secondary" patents are commonly the subject of Paragraph IV challenges by generic drug makers.

Because Keytruda's earliest patent has already expired, generic versions are technically clear to enter the market for that specific patented composition. Whether a generic is actually available depends on FDA Orange Book listings for any later patents, ANDA approvals, and any ongoing Paragraph IV settlements. Patients and prescribers should check the FDA's Orange Book or GoodRx for current generic availability.

For the authoritative listing of patents tied to a specific drug — the patents an ANDA filer is legally required to address under 21 USC § 355(j) — consult the FDA Orange Book. Underlying utility patent data on this page is sourced from USPTO PatentsView, the federal government's free public patent API.

Keytruda is protected by 15 US patents — a large portfolio that signals an aggressive lifecycle management strategy. Mega-portfolios of 15+ patents are characteristic of top-selling drugs (Humira famously had over 130) where the manufacturer has built layered protection across composition, multiple formulations, dosing schedules, drug-device combinations, and method-of-use claims for individual indications. These layered portfolios typically face Paragraph IV litigation under the Hatch-Waxman framework as generic challengers test secondary patents one by one.

All 15 patents in the Keytruda portfolio are assigned to Merck Sharp & Dohme LLC, indicating consolidated ownership. Single-assignee portfolios are simpler to litigate and easier to license — generic challengers face one negotiating counterparty, and any settlement or pay-for-delay arrangement involves only that holder.

The Keytruda portfolio scores 40/100 (Grade D, "weak") on the PatentCliff Strength index. The strongest signal is claims breadth (71/100), and the weakest is technology diversity (15/100). The four factors are weighted by how well they predict real-world resilience to generic challenge: portfolio size 30%, claims breadth 25%, time remaining 25%, and technology diversity 20%.

Looking at the 15 dated patents in the portfolio, the largest cluster (5 patents) falls in the "Beyond 2036" bucket. That distribution matters because generic entry is gated by the latest unexpired blocking patent, not the earliest — even one late-expiring formulation patent can delay biosimilar launch by years if it survives a Paragraph IV challenge.

The 20-year patent term in the United States runs from the earliest non-provisional filing date, not the grant date. That means a patent granted in 2015 from a 2010 filing has only 15 years of life left at grant — a feature of US patent law that creates the layered "cliff" pattern visible in most branded drug portfolios. Patent Term Extension under 35 USC § 156 can add up to 5 years for time lost to FDA review, and pediatric exclusivity can add 6 months on top.