Yervoy (ipilimumab) is a monoclonal antibody drug used to treat advanced melanoma. It works by blocking a protein called CTLA-4 on T-cells, which allows the immune system to attack cancer cells. According to DrugPatentWatch [1], the patent for Yervoy expired in the United States on October 27, 2020. This means that generic versions of the drug may now be available in the market.

Bristol Myers Squibb, the manufacturer of Yervoy, has been facing a series of patent expirations in recent years. As reported by FiercePharma [2], Yervoy was one of the top 15 blockbuster drugs facing patent expiration in the decade from 2015 to 2024. The loss of patent protection for Yervoy is expected to have a significant impact on the company's revenue. However, Bristol Myers Squibb has been working to mitigate the impact by developing new drugs and expanding its portfolio.

In its 2015 annual report [3], Bristol Myers Squibb noted that the expiration of Yervoy's patent in the United States would have a "significant impact" on its financial results. The company also stated that it was "actively managing" the impact of patent expirations by investing in research and development, pursuing strategic collaborations, and seeking regulatory approvals for new products.

In conclusion, the patent for Yervoy expired in the United States on October 27, 2020, which may result in the availability of generic versions of the drug. Bristol Myers Squibb has been anticipating the impact of patent expirations and has been taking steps to mitigate the impact by developing new drugs and expanding its portfolio.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/YERVOY
[2] https://www.fiercepharma.com/special-report/top-15-blockbuster-patent-expirations-coming-decade
[3] https://www.sec.gov/Archives/edgar/data/14272/000001427216000288/bmy-20151231x10xk.htm