Arbutus and Sanofi Escalate mRNA Patent Battles Against Pfizer, BioNTech and Moderna

Arbutus Biopharma and its partner Genevant Sciences have filed three new lawsuits against Pfizer and BioNTech, escalating the patent war over mRNA vaccine technology. The actions come a week after Arbutus collected roughly $178 million from a settlement with Moderna on 8 July 2026, fresh firepower now directed at the makers of Comirnaty.

Two of the complaints were filed before the Unified Patent Court under case numbers PR-UPC-CFI-0002562/2026 and PR-UPC-CFI-0002566/2026, targeting European patents EP 4 241 767 and EP 4 495 237. A third action was brought in Canada, broadening the fight into an array of European countries as well as Canada. The new legal actions ratchet up longstanding efforts that aim to prove the companies' COVID vaccine infringed on Arbutus patents, which cover a kind of lipid nanoparticle technology used to help deliver vaccines into cells.

In March, Arbutus and Genevant Sciences, a unit of Roivant Sciences, reached a global settlement with Moderna worth up to $2.25 billion to resolve a long-running dispute over technology used in Moderna's COVID-19 vaccines. Under the agreement, Moderna is required to make a $950-million upfront payment by July 8. Arbutus expects to receive approximately $179 million of that amount after costs, while the remaining goes to Genevant Sciences. The company has said it is evaluating ways to return capital to shareholders later this year once the funds arrive.

Sanofi separately initiated two other lawsuits against Pfizer and Moderna in the U.S. District Court of New Jersey on 14 July. Sanofi is targeting Pfizer over Comirnaty and Moderna over Spikevax and mNexspike, asserting eight patents against Pfizer and ten against Moderna. The claims, inherited from its $3.2 billion acquisition of Translate Bio in 2021, cover mRNA purification methods and encapsulation in lipid nanoparticles. Sanofi is seeking a trial, damages and other financial relief, but is not seeking an injunction, only what it calls "reasonable compensation."

On February 17, 2026, the U.S. District Court for the District of Delaware issued a memorandum and order in the patent infringement case brought by Arbutus and Genevant against Moderna over the mRNA-1273 COVID-19 vaccine. The court held that Moderna is estopped from re-litigating many obviousness challenges to Arbutus's patents that it had already raised or could have raised in earlier inter partes review proceedings, narrowing Moderna's defenses. The court also found that Moderna lacks sufficient evidence to support its derivation defense but allowed its enablement defense to proceed to a jury based on admissible expert opinions that create factual disputes.

The disputes center on lipid nanoparticles (LNPs) — the tiny fat particles that protect and deliver mRNA into human cells. Without effective LNPs, mRNA vaccines like Moderna's Spikevax would not work well. Arbutus had developed and patented specific LNP formulations years before the pandemic.

In the meantime, Arbutus is also progressing its main drug candidate for chronic hepatitis B, imdusiran, which received U.S. FDA Fast Track designation in April. The company reported positive early clinical results for the drug. Arbutus has also announced plans to return up to $230 million to its shareholders through buybacks starting in the third quarter, plus an expected dividend from Genevant. The company had total cash, cash equivalents, and marketable securities of $95.2 million as of the end of the first quarter.