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As Pfizer faces growing concerns about the impact on sales from recent warnings about the Xeljanz pulmonary embolism risk, the maker of the new-generation rheumatoid arthritis drug is also fighting off competition, filing a lawsuit against Ajanta Pharma, Ltd over its plans to release a generic Xeljanz equivalent.
In a complaint (PDF) filed last month in the U.S. District Court for the District of Delaware, Pfizer claims that Ajanta would violate the company’s patent protections if it obtains approval for aa generic tofacitinib 5mg tablet.
Xeljanz (tofacitinib) was first approved by the FDA in 2012, to treat adults with rheumatoid arthritis, an autoimmune disorder that causes inflammation of the joints in approximately one percent of the population.
The drug is the first member of a new class of medications, known as Janus kinase (JAK) inhibitors, which works by blocking the activity of certain enzymes in the body that affect immune system function.
Since it was introduced, Xeljanz has quickly grown to become a blockbuster drug, and is commonly used as an alternative treatment for patients who have tried methotrexate and other medications without success.
In December 2017, the FDA approved the use of Xeljanz and Xeljanz XR for the treatment of active psoriatic arthritis (PsA), and then approval was expanded again in May 2018 to include treatment of moderate to severe active ulcerative colitis.
According to the lawsuit, Ajanta has filed an Abbreviated New Drug Application (ANDA) seeking approval from the U.S. Food and Drug Administration to sell a generic version of the 5 mg Xeljanz tablets. However, Pfizer claims that the Xeljanz patent extends until 2027, meaning another manufacturer would not be able to release a generic version of the medication until after that protection expires.
Ajanta has indicated that it does not believe Xeljanz’s patent protection is valid.
Xeljanz Blood Clot Side Effects
The patent battle comes amid recent warnings by U.S. and foreign regulators about potential new, and life-threatening, side effects of Xeljanz, as preliminary results from an ongoing study found that users may be more likely to suffer a blood clot in the lung or death, especially at higher doses.
In February, Pfizer announced data from the Xeljanz clinical trial results, indicating that individuals taking a 10 mg twice daily dose of Xeljanz twice daily faced a five-fold increase in pulmonary embolism when compared to other types of rheumatoid arthritis drugs, and a three fold increase when compared to lower doses of Xeljanz.
As a result of the findings, a warning by the FDA now indicates that doctors should closely monitor patients taking Xeljanz for pulmonary embolism, and that patients should seek immediate medical attention if they experience signs or symptoms of a blood clot.
It appears likely that Pfizer may face Xeljanz lawsuits over failure to previously warn about the pulmonary embolism risk.