Enanta sues Pfizer for Paxlovid-related patent infringement

USA – Enanta has filed suit against Pfizer in district court in Massachusetts, seeking damages for infringement on a patent it originally filed back in July 2020.

Specifically, Enanta is claiming that Pfizer’s nirmatrelvir, the newly-developed half of Paxlovid, violates Enanta’s patent on multiple fronts for its protease inhibitor Covid-19 drug candidate.

While Enanta said it does not want to halt the sale, distribution or production of Paxlovid, it also said it wants to be reimbursed with what it calls “fair compensation.”

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 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.

Paxlovid is an oral antiviral pill for high-risk patients that is intended to stave off serious complications from COVID-19.

Meanwhile, Pfizer raked in US$1.5 billion in sales of the antiviral in the first quarter. Pfizer said last month it expects to make US$22 billion from Paxlovid sales this year.

The suit follows Enanta’s decision to start dosing patients in clinical trials with its own protease inhibitor for Covid-19 in February, receiving a fast track designation from the FDA along the way.

This is not Pfizer’s first time being sued as it relates to its Covid-19 products. In March, RNAi therapeutics giant Alnylam filed suit against both Pfizer-BioNTech and Moderna over their Covid-19 vaccines.

In the litigation Alnylam based in Cambridge, Massachusetts sought royalties for the Lipid nanoparticle (LNP) technology the shots use to deliver genetic material known as mRNA.

However, in a Securities and Exchange Commission (SEC) filing earlier this month, Pfizer said that Alnylam’s technology has played no role in the success of its vaccine.

The number of patent lawsuits over COVID vaccines and treatments has risen in recent months. Multiple pharmaceutical companies have sued Pfizer and Moderna Inc over technology used in their vaccines, and Regeneron Pharmaceuticals Inc is facing a lawsuit over its breakthrough COVID antibody cocktail.

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