Pfizer, Enanta Launch Dueling Bids to Gut Paxlovid Patent Case

Pfizer Inc. and Enanta Pharmaceuticals Inc. are both seeking early wins in their two-year fight over patent rights to the blockbuster Covid-19 treatment Paxlovid.

Enanta asked Judge Denise J. Casper to declare that the chemical structure of nirmatrelvir, a key active ingredient in Paxlovid, infringes its own patented antiviral agent, while Pfizer urged her to invalidate that patent as anticipated by one of its own, according to separate summary judgment motions filed Tuesday in the US District Court for the District of Massachusetts.

Nirmatrelvir infringes claims in Enanta’s US Patent No. 11,358,953, Enanta said in its filing asking for summary ...