A dispute over a key technology used in Moderna’s highly anticipated COVID-19 vaccine came to a head in July when Arbutus Biopharma fended off a claim by the vaccine maker. The patent clash over the delivery system used in Moderna’s mRNA-1273 vaccine could hamper the biotech’s ability to price the vaccine competitively, as well as affect its margins versus those of other companies developing coronavirus vaccines. Moderna previously held a limited sublicense to Arbutus Biopharma’s lipid nanoparticle (LNP) formulation, which is used to deliver messenger RNA drugs into cells. But since 2018, Moderna has filed three inter partes reviews (IPRs) with the US Patent and Trademark Office seeking to invalidate Arbutus’s LNP patents. The first two IPRs resulted in wins for Moderna — invalidating one of Arbutus’s patents in full and partially invalidating another. However, on 23 July the US Patent and Trademark Office’s Patent Trial and Appeal Board (PTAB) delivered a decisive win for Arbutus in the third IPR, rejecting Moderna’s argument that the Arbutus patent known as the ’069 patent should be revoked because it describes obvious concepts. “To the extent it is believed the PTAB erred in their decisions, Moderna may further pursue these matters,” the company said in a statement, adding that they were “not aware of any significant intellectual property impediments for any products we intend to commercialize, including mRNA-1273.” Though it is still unclear whether Moderna’s vaccine development efforts use the LNP technology in question, the PTAB’s ruling increases the pressure on Moderna to seek a sublicense on the technology. The ’069 patent is licensed to Genevant Sciences, a maker of LNPs for RNA-based therapeutics, and Arbutus would receive 20% of any revenue received by Genevant for sublicensing the patent. Analysts at investment bank SVB Leerink called the decision a “disappointing turn” for Moderna in a note to investors.