Enanta sues Pfizer for infringement on Paxlovid, citing a patent it was granted a week ago

Earlier this year, Enanta Pharmaceuticals said it was entering the clinic with a COVID-19 treatment that might eventually challenge Pfizer’s antiviral Paxlovid.

Five months later, the biotech has revealed a more immediate challenge to Pfizer, filing suit in U.S. district court in Massachusetts claiming (PDF) that the pharma giant infringed on a patent for its protease inhibitor COVID drug in creating Paxlovid.

The United States granted patent No. 11,358,953 to Enanta last week after the company filed a patent application in July 2020. In March of this year, the technology helped the company secure fast-track designation for its COVID drug candidate.

Enanta wants a jury trial and seeks damages for the infringement at an amount “no less than a reasonable royalty for the use made by Pfizer of Enanta’s invention,” the suit reads.

The biotech said that it would not pursue an injunction or take other action that would impede sales of the highly successful Pfizer drug used to treat at-risk patients who have been infected with the virus. Pfizer raked in $1.5 billion in sales of the antiviral in the first quarter.

A Pfizer spokesperson said that the company had “no comment at this time,” on the lawsuit.

In its filing, Enanta included a detailed, 59-page breakdown of the patent.

The 27-year-old company specializes in the development of small molecule drugs to treat infections and liver diseases. It’s R&D activities are funded by royalties from hepatitis C virus (HCV) products developed in collaboration with AbbVie, including Mavyret.

Last month, Enanta’s stock tumbled to its lowest level in five years when it revealed the failure of a phase 2b trial of its N-protein inhibitor EDP-938 to treat low-risk respiratory syncytial virus (RSV) patients.

Pfizer also is facing a patent infringement suit from Alnylam on the delivery technology its COVID-19 vaccine. In an SEC filing earlier this month, Pfizer said that Alnylam's technology has played no role in the success of its vaccine.