Court Bars Arbutus Biopharma's Doctrine of Equivalents Claims in Moderna Patent Suit
ABUS sits 43% above its 52-week low of $2.705.
Summary
A U.S. District Court issued a mixed ruling in Arbutus Biopharma's patent infringement lawsuit against Moderna, significantly limiting Arbutus's ability to claim infringement under the doctrine of equivalents for several key patents.
Key Events · Legal and Risk Events · ABUS
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Doctrine of Equivalents Barred for Key Patents
The court granted Moderna's motion, preventing Arbutus from using the doctrine of equivalents for infringement claims on Molar Ratio Patents (U.S. Patent Nos. 8,492,359, 9,364,435, and 11,141,378). This requires Arbutus to prove literal infringement, a higher legal standard.
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Jurisdiction Split for Moderna Vaccine Sales
Claims related to Moderna vaccine doses sold to the general public will remain in District Court, while claims for doses distributed directly to U.S. Government employees must be pursued in the Court of Federal Claims. Indirect infringement claims against Moderna remain in District Court.
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Patent Invalidity to be Decided by Jury
The court denied summary judgment on the indefiniteness of Arbutus's '651 Patent and Molar Ratio Patents, meaning a jury will ultimately decide their validity.
Analysis · ABUS · Life Sciences
The U.S. District Court for the District of Delaware delivered a critical ruling in the ongoing patent infringement litigation between Arbutus Biopharma and Moderna. While the court allowed most of Arbutus's claims regarding Moderna's COVID-19 vaccine sales to the general public to proceed in District Court, it dealt a significant blow to Arbutus by granting Moderna's motion on prosecution history estoppel. This means Arbutus is barred from asserting infringement claims under the doctrine of equivalents for U.S. Patent Nos. 8,492,359, 9,364,435, and 11,141,378 (Molar Ratio Patents). Arbutus will now need to prove literal infringement for these patents, which is a higher legal hurdle. The court also denied summary judgment on the invalidity of Arbutus's patents, leaving that for a jury to decide. This ruling, following a recent European patent revocation on January 16, 2026, adds further complexity and risk to Arbutus's intellectual property position.
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At the time of this filing, ABUS was trading at $3.87 on NASDAQ in the Life Sciences sector, with a market capitalization of approximately $738.5M. The 52-week trading range was $2.71 to $5.10. This filing was assessed with negative market sentiment and an importance score of 8 out of 10.