When Does Rituxan Patent Expire?

Rituxan is at the front edge of its patent cliff. The earliest expiration falls in 2026 — under two years from today — which is the conventional window in which generic manufacturers file Abbreviated New Drug Applications (ANDAs) and biosimilar developers begin commercial planning. Full portfolio coverage extends to 2042, a 16-year tail that typically drives litigation over secondary patents.

Because Rituxan's patent cliff is within three years, generic manufacturers are likely already preparing ANDA filings or have filed Paragraph IV certifications. Under Hatch-Waxman, the first successful Paragraph IV challenger earns a 180-day exclusivity period as the sole generic. Watch FDA's Paragraph IV certification list for filing activity tied to Rituxan.

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.

Rituxan is protected by 10 US patents, a mid-sized portfolio that is typical for an established branded drug in mid-lifecycle. The portfolio likely combines a primary composition-of-matter patent (the strongest form of protection) with a layer of formulation, dosing, and method-of-use patents that extend exclusivity beyond the original composition expiry — a common strategy known as "patent layering" or, less charitably, "evergreening."

Rituxan patent rights are held across 2 entities: Genentech Inc., Biogen Inc.. Multi-assignee portfolios usually reflect co-development partnerships, licensing splits between an originator and a marketing partner, or assignments made during corporate restructurings. Multi-party ownership can complicate generic entry — a challenger may need to clear patents from each holder separately, and settlements are harder to reach.

The Rituxan portfolio scores 39/100 (Grade D, "weak") on the PatentCliff Strength index. The strongest signal is claims breadth (73/100), 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 10 dated patents in the portfolio, the largest cluster (3 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.