Pfizer calls in the lawyers to block would-be rival to extended-release Xeljanz

Medical justice
Sales of the standard and extended-release versions of Xeljanz hit $2.4 billion in 2020. (Getty/yavdat)

Sinotherapeutics wants to start selling a generic version of Pfizer’s extended-release JAK inhibitor Xeljanz XR. Pfizer has other ideas, prompting it to file a lawsuit setting out its objections to the plan.

In the lawsuit (PDF), Pfizer highlights three Xeljanz XR patents that are set to expire between 2023 and 2034. The long-term barrier to Xeljanz XR copies is 9,937,181, a patent covering a once-daily 11 mg formulation of tofacitinib that is set to expire in 2034. Sinotherapeutics plans to bring a generic version of Xeljanz XR to market before 2034 in the belief it can bypass the ‘181 patent.

According to Pfizer, Sinotherapeutics said it “will not infringe the claims of the ’181 [p]atent by the manufacture, use, sale, offer to sell in the United States or importation into the United States of” its generic Xeljanz XR copy. 

Sinotherapeutics made the statement in a notice to Pfizer about the filing of an abbreviated new drug application that could position it to sell its extended-release tofacitinib in the U.S. before the expiration of the ‘181 patent. The notice lacks an argument about why the ‘181 patent is invalid, Pfizer said in its lawsuit. 

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While Sinotherapeutics says it will not infringe any claim of the patent, Pfizer sees things differently. The lawsuit filed by Pfizer in the U.S. District Court for the District of Delaware sets the stage for a legal row over which side is in the right. Pfizer wants the court to issue an injunction blocking the sale of the generic until the ‘181 patent expires and to tell Sinotherapeutics to cover its legal costs. 

The lawsuit may affect a blockbuster franchise. Sales of the standard and extended-release versions of Xeljanz hit $2.4 billion in 2020, up 9% over the previous year. Pfizer reported rising volumes in indications including rheumatoid arthritis.