Delaware Court Narrows Moderna’s Invalidity Defenses Ahead of Arbutus LNP Patent Trial

The U.S. District Court for the District of Delaware on Tuesday granted in part and denied in part a motion for summary judgment in Arbutus Biopharma Corp. v. Moderna, Inc., narrowing the invalidity defenses that Moderna can assert at a jury trial. U.S. District Judge Joshua D. Wolson precluded Moderna from challenging several Arbutus patents on obviousness and derivation grounds but found that Moderna had raised a genuine factual dispute regarding enablement that must be resolved by a jury.

The ruling comes weeks before the trial is scheduled to begin on March 9, 2026, and follows earlier rulings Judge Wolson issued in the case on February 2. In that earlier ruling, the court held 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, keeping essentially all of Moderna’s over $8.2 billion in vaccine sales to the Government in the case. The court also held 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.

The dispute involves four patents owned by Arbutus that relate to nucleic acid-lipid nanoparticles (LNPs), a key technology for delivering messenger RNA (mRNA), such as the mRNA used in Moderna’s COVID-19 vaccine. These three U.S. Patent Nos. 8,492,359, 9,364,435, and 11,141,378 are part of the same family and are referred to as the “Molar Ratio Patents.” These patents claim specific molar ratio ranges for the four lipid components, a cationic lipid, a phospholipid, cholesterol, and a conjugated lipid, that make up the LNPs. Additionally, the U.S. Patent No. 9,504,651 claims a formulation of lipid vesicles with high levels of fully encapsulated mRNA.

Arbutus filed a lawsuit on February 28, 2022, and later moved for summary judgment on three of Moderna’s invalidity defenses, arguing that obviousness, enablement, and derivation should be dismissed as a matter of law. The court agreed with Arbutus on the obviousness and derivation defenses but sided with Moderna that its enablement challenge should proceed to trial.

Regarding the obviousness defense, the court found that inter partes review (IPR) estoppel and the common law doctrine of issue preclusion barred Moderna’s arguments. Moderna had previously challenged the ‘435 patent in an IPR proceeding before the Patent Trial and Appeal Board (PTAB) and issued a final written decision rejecting Moderna’s invalidity challenge. The court held that IPR estoppel under 35 U.S.C. § 315(e)(2) prevents Moderna from re-litigating the same arguments or any that could have been reasonably raised. The court rejected Moderna’s contention that estoppel should not apply because the U.S. Court of Appeals for the Federal Circuit (CAFC) dismissed its subsequent appeal for lack of standing. Judge Wolson wrote that “IPR estoppel is not a common law doctrine; it is a Congressional creation,” and the statutory text triggers estoppel upon the PTAB’s final written decision, regardless of a petitioner’s ability to appeal.

The court found that the PTAB and the CAFC had already rejected Moderna’s arguments that “routine optimization” would have led to the claimed molar ratios and that the prior art disclosed an overlapping phospholipid range. The opinion explained that a defendant’s attempt to buttress its case through different evidence does not necessarily create a new issue. As a result of these findings, the court also granted Arbutus’s motion to exclude the obviousness opinions of Moderna’s expert, Dr. Daniel Anderson.

However, the court denied Arbutus’s motion for summary judgment on enablement. The court found that the opinions of Moderna’s expert, Dr. Robert Prud’homme, were admissible and created a genuine issue of material fact for the jury. Dr. Prud’homme concluded that the asserted claims require undue experimentation to practice, analyzing the factors set forth in the Federal Circuit’s decision, In re Wands. The court determined that Dr. Prud’homme’s analysis satisfied the requirements for expert testimony and would help the jury determine a fact in issue. Judge Wolson stated that while Arbutus may have competing evidence, “Trials are the time to assess competing evidence, not motions practice.” The court will therefore “permit a jury to resolve questions of enablement.”

Furthermore, the court granted summary judgment to Arbutus on Moderna’s derivation defense. To prove derivation, an invalidity defense under 35 U.S.C. § 102(f), Moderna needed to show that another inventor conceived of the invention and communicated that conception to the Arbutus inventors, the court explained. Moreover, the court found that Moderna had failed to demonstrate a prior conception. The opinion noted that Moderna’s own expert conceded that an Arbutus scientist, Stephen Reid, had successfully practiced a key element of the ‘651 patent’s claimed invention in 2009, years before Moderna’s proposed prior conception date. The court also explained that Mr. Reid’s work, which was conducted at the request of a named inventor, inured to the benefit of that inventor for the purposes of establishing a reduction to practice.

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Author: thodonal