Delaware Court Narrows Moderna's Patent Defenses in $8.2 Billion Arbutus LNP Technology Dispute
Key Insights
A Delaware federal court has significantly limited Moderna's invalidity defenses ahead of a March 2026 trial, blocking the company's obviousness and derivation challenges to Arbutus patents covering lipid nanoparticle technology used in COVID-19 (search) vaccines.
The court ruled that over $8.2 billion in Moderna's government vaccine sales remain subject to the patent dispute after rejecting Moderna's Section 1498 defense, determining that vaccine use benefited patients rather than the government itself.
Arbutus faces a heightened burden to prove patent infringement after the court applied prosecution history estoppel, requiring literal infringement rather than allowing claims under the doctrine of equivalents.
A Delaware federal court has delivered a mixed ruling that significantly narrows the scope of patent defenses available to Moderna while maintaining the company's exposure to over $8.2 billion in damages in a high-stakes dispute over lipid nanoparticle technology used in COVID-19 (search) vaccines.
U.S. District Judge Joshua D. Wolson granted in part and denied in part Arbutus Biopharma's motion for summary judgment on February 18, 2026, just weeks before trial is scheduled to begin on March 9. The ruling prevents Moderna from challenging several Arbutus patents on obviousness and derivation grounds but allows the company's enablement defense to proceed to jury trial.
Court Blocks Key Moderna Defenses
The court found that inter partes review (IPR) estoppel and common law issue preclusion bar Moderna's obviousness arguments. Moderna had previously challenged one of the patents in an IPR proceeding before the Patent Trial and Appeal Board (PTAB), which issued a final written decision rejecting Moderna's invalidity challenge.
Judge Wolson rejected Moderna's contention that estoppel should not apply because the U.S. Court of Appeals for the Federal Circuit dismissed its subsequent appeal for lack of standing. "IPR estoppel is not a common law doctrine; it is a Congressional creation," the judge wrote, explaining that the statutory text triggers estoppel upon the PTAB's final written decision, regardless of a petitioner's ability to appeal.
The court determined that the PTAB and Federal Circuit had already rejected Moderna's arguments that "routine optimization" would have led to the claimed molar ratios and that prior art disclosed an overlapping phospholipid range. As a result, the court also granted Arbutus's motion to exclude the obviousness opinions of Moderna's expert, Dr. Daniel Anderson.
Enablement Challenge Survives
However, the court denied Arbutus's motion for summary judgment on enablement, finding that opinions from Moderna's expert Dr. Robert Prud'homme created a genuine issue of material fact for the jury. Dr. Prud'homme concluded that the asserted claims require undue experimentation to practice, analyzing factors set forth in the Federal Circuit's In re Wands decision.
"Trials are the time to assess competing evidence, not motions practice," Judge Wolson stated, determining that the court will "permit a jury to resolve questions of enablement."
Derivation Defense Rejected
The court granted summary judgment to Arbutus on Moderna's derivation defense under 35 U.S.C. § 102(f). To prove derivation, Moderna needed to show that another inventor conceived of the invention and communicated that conception to the Arbutus inventors. The court found that Moderna failed to demonstrate prior conception, noting that Moderna's own expert conceded that Arbutus scientist Stephen Reid had successfully practiced a key element of one patent's claimed invention in 2009, years before Moderna's proposed prior conception date.
$8.2 Billion in Sales Remain at Stake
In an earlier February 2 ruling, Judge Wolson determined that the phrase "for the Government" in 28 U.S.C. § 1498 means the use of a patented product must be for the benefit of the Government itself, not the benefit of patients who receive it. This interpretation keeps essentially all of Moderna's over $8.2 billion in vaccine sales to the Government within the scope of the case.
The court heavily relied on Larson v. United States, where the Court of Federal Claims stated that "medical care is provided for the benefit of the patient, not the Government." The Section 1498 defense applies only to vaccines the Government provided to its employees, which Arbutus alleges amounts to just 1.25% of total government sales.
Prosecution History Estoppel Limits Arbutus Claims
The court also ruled that Arbutus's removal of the term "about" from its claimed lipid ranges during patent prosecution invoked prosecution history estoppel, foreclosing Arbutus from asserting infringement under the doctrine of equivalents. This requires Arbutus to prove its case based on literal infringement, a heightened standard.
The court noted that "Moderna used LNP technology with molar ratio ranges that differed slightly from those listed in Arbutus's Molar Ratio Patents," making the precise lipid ratios crucial since any ratios falling outside claimed ranges would preclude literal infringement.
Patent Technology at Center of Dispute
The dispute involves four patents owned by Arbutus relating to nucleic acid-lipid nanoparticles (search) (LNPs), key technology for delivering messenger RNA (search) used in Moderna's COVID-19 (search) vaccine. Three patents (U.S. Patent Nos. 8,492,359, 9,364,435, and 11,141,378) are referred to as the "Molar Ratio Patents" and claim specific molar ratio ranges for four lipid components: cationic lipid, phospholipid, cholesterol, and conjugated lipid. U.S. Patent No. 9,504,651 claims a formulation of lipid vesicles with high levels of fully encapsulated mRNA (search).
Arbutus filed the lawsuit on February 28, 2022, after four years of case development leading to the March 2026 trial date. The ruling represents a split decision, with Moderna facing continued exposure to billions in potential damages while Arbutus confronts a more challenging path to proving infringement.