European patent for Pozen’s (NASDAQ: POZN) combination drug technology is valid and will continue to stand, according to a decision issued by European patent authorities.

The Chapel Hill drug developer said that the Opposition Division of the European Patent Office has maintained Pozen’s patent covering the combination of proton pump inhibitors (PPI) and non-steroidal anti-inflammatory drugs. This combination is key to Pozen’s osteoarthritis drug Vimovo as well as the company’s PA platform, which is being used to develop drug candidates that aim to deliver aspirin in a manner that is safer on the stomach.

In 2011, Chatfield Pharmaceuticals of Britain and and another unnamed company challenged Pozen’s patent asserting that the European patent should not have been granted. The unnamed company later withdrew from the proceedings. Chatfield has until May 5 to appeal the decision. Pozen said that if an appeal is filed, a decision could take two years.

The European patent on Pozen’s combination drug technology will expire in May 2022. Pozen has obtained supplement protection certificates for Vimovo, which extend patent protection to October 2025. Pozen plans to apply for the same protection for PA upon that drug’s approval. During the company’s earnings conference call last week, CEO John Plachetka said that a drug application is expected to be filed in the second quarter.

Pozen’s patents for the combination drug technology outside of the United States and Europe are set to expire in 2022.