In the ongoing patent litigation between Moderna and Arbutus Biopharma Corporation, a federal judge has restricted the scope of testimony that Moderna’s damages expert can present regarding reasonable royalty calculations. This decision, issued on February 25, 2026, comes as the parties prepare for a jury trial scheduled to commence on March 9, 2026, in the U.S. District Court for the District of Delaware.
The court’s ruling specifically excludes portions of the expert’s testimony deemed unreliable, thereby limiting Moderna’s ability to argue for lower damages based on certain royalty rate assessments. This development is part of a broader legal battle in which Arbutus and its licensee, Genevant Sciences GmbH, allege that Moderna’s COVID-19 vaccine infringes upon six U.S. patents related to lipid nanoparticle (LNP) technology. These patents are critical for the delivery of messenger RNA into human cells, a foundational component of Moderna’s vaccine platform.
In a related decision, the court has also narrowed Moderna’s invalidity defenses. On February 18, 2026, U.S. District Judge Joshua D. Wolson granted in part Arbutus’s motion for summary judgment, barring Moderna from challenging several Arbutus patents on grounds of obviousness and derivation. The judge determined that inter partes review (IPR) estoppel and common law issue preclusion prevent Moderna from reasserting these arguments, as the Patent Trial and Appeal Board (PTAB) had previously issued a final written decision rejecting Moderna’s invalidity challenge. The court noted that “IPR estoppel is not a common law doctrine; it is a Congressional creation,” emphasizing that estoppel applies upon the PTAB’s final decision, irrespective of a petitioner’s ability to appeal.
Furthermore, the court rejected Moderna’s defense under 28 U.S.C. § 1498, which would have shifted liability to the U.S. government for the alleged infringement. The judge found that this defense applies only to vaccines provided directly to government employees, accounting for merely 1.25% of total government sales, thereby leaving over $8.2 billion in Moderna’s vaccine sales subject to the patent dispute.
Conversely, the court’s application of prosecution history estoppel imposes a higher burden on Arbutus to prove infringement. By removing the term “about” from its claimed lipid ranges during patent prosecution, Arbutus is now required to demonstrate literal infringement, as the doctrine of equivalents is foreclosed. This means that any deviation from the specified lipid ratios in Moderna’s LNP technology could preclude a finding of infringement.
The patents at the center of this dispute include U.S. Patent Nos. 8,492,359, 9,364,435, and 11,141,378, collectively referred to as the “Molar Ratio Patents,” which claim specific molar ratio ranges for four lipid components. Additionally, U.S. Patent No. 9,504,651 claims a formulation of lipid vesicles with high levels of fully encapsulated mRNA. These patents are integral to the LNP technology utilized in Moderna’s COVID-19 vaccine.
As the trial date approaches, these judicial decisions significantly shape the legal landscape for both parties. Moderna faces the challenge of defending against substantial damages claims without the benefit of certain expert testimonies and invalidity defenses. Meanwhile, Arbutus must meet a heightened standard of proof to establish literal infringement of its patents. The outcome of this case could have far-reaching implications for the biotechnology industry, particularly concerning the development and commercialization of mRNA-based therapies.