2031, date not disclosed
Imfinzi expected to lose US exclusivity
Company guidance. AstraZeneca 20-F: US patent protection expected to 2031.
When does Imfinzi go off patent?
In the US, biosimilars can launch from 2031. Imfinzi is sold by AstraZeneca. AstraZeneca 20-F: US patent protection expected to 2031.
Imfinzi's US exclusivity date is based on company guidance. The date comes from the company's own filings or guidance. Secondary patents, new formulations or litigation can still move it. It is a biologic, so copies are biosimilars. Biosimilars are harder to make and usually erode sales more gradually than generics.
| Patent or protection | Covers | Expiry |
|---|---|---|
| US patents (AstraZeneca) | Durvalumab, including extensions | 2031 |
| FDA orphan exclusivity | One approved use | 4 December 2031 |
| EU and China patents | Durvalumab (Europe, China) | 2030 |
| Japan patents | Durvalumab (Japan) | 2033 |
AstraZeneca lists US patent protection for Imfinzi to 2031, including extensions, with 2030 in Europe and China and 2033 in Japan. Its 12-year US biologic exclusivity, from approval in May 2017, ends in 2029, so the patents set the date. Alvotech is developing a biosimilar; we found no US filing.
Sources: AstraZeneca 20-F 2025 · FDA Purple Book
| Year | Worldwide | US | Growth |
|---|---|---|---|
| 2023 | $4.02B | $2.17B | – |
| 2024 | $4.72B | $2.60B | +17% |
| 2025 | $6.06B | $3.51B | +29% |
2023 as restated in the 2025 20-F. Worldwide net sales as reported, with the US share. Source: AstraZeneca 20-F 2025
Early development Alvotech is developing an Imfinzi biosimilar (AVT34), licensed to Lotus in August 2026. We found no US filing.
| Company (product) | Stage |
|---|---|
| Alvotech (AVT34) | Early development |
Checked October 2026. Sources: Goodwin: Alvotech and Lotus
Among past biologics facing biosimilars, US sales in the first full year after copies arrived were a median 65% of the last full year before (range 34% to 93%, 7 drugs), and 27% by the third year (9 drugs). Biosimilars usually take share more gradually than generics. Every drug is different: settlements, how many copies launch, and pricing all change the curve. See the erosion benchmarks →
| Scenario | 2025 US sales | Year 1 (about 2032) | Year 2 | Year 3 |
|---|---|---|---|---|
| Fastest past case | $3.51B | $1.19B34% | $0.37B11% | $0.15B4% |
| Median | $3.51B | $2.29B65% | $1.35B38% | $0.93B27% |
| Slowest past case | $3.51B | $3.28B93% | $2.66B76% | $2.23B64% |
An illustration, not a forecast: it applies the past-cliff benchmarks to Imfinzi's 2025 US sales, held flat until copies arrive in 2031. Year 1 is the first full year with copies on sale.
Imfinzi is 10% of AstraZeneca's 2025 revenue ($6.1B of $58.7B). With Farxiga, Lynparza, Tagrisso, Calquence and Ultomiris, the drugs tracked here add up to 57% of AstraZeneca's revenue losing US exclusivity by 2035.
Bars show each company's tracked drugs as a share of its total 2025 revenue. Imfinzi is highlighted.
Company guidance. AstraZeneca 20-F: US patent protection expected to 2031.