Arbutus Biopharma (ABUS) drops 13.62% as EPO revokes key European patent

Arbutus Biopharma (ABUS) dropped 13.617% in pre-market trading on January 20, 2026, following the European Patent Office’s Board of Appeal revoking its key European patent EP 2279254. The decision overturned the patent’s previous upholding by the EPO’s Opposition Division and could impact ongoing litigation against Moderna in Switzerland and the Unified Patent Court. Arbutus plans to appeal the ruling to the Enlarged Board of Appeal once the written decision is finalized, expected in the coming months.

The patent, central to the company’s legal and commercial strategy, had faced opposition from Moderna and Merck affiliates since 2018. While the revocation does not affect U.S., Japanese, or Canadian infringement proceedings, it raises uncertainties for Arbutus’ intellectual property (IP) portfolio. The company remains focused on its hepatitis B virus (HBV) pipeline, including RNAi therapeutic imdusiran and LNP delivery technology, including , but the IP challenge may heighten near-term risks. Analysts note mixed signals in valuation metrics, with high price-to-sales and price-to-book ratios contrasting against strong liquidity and low debt levels.

Arbutus’ resilience in balance sheet metrics, such as a 18.8 current ratio and 18.08 cash ratio, underscores its financial stability despite operational losses. However, the patent ruling adds pressure to a sector already grappling with regulatory and competitive hurdles. The stock’s sharp pre-market decline reflects investor concerns over IP vulnerability and potential setbacks in its HBV therapeutic development timeline.

Looking ahead, stakeholders are closely monitoring how this legal shift might affect future patent strategies and litigation tactics in the biotech industry. The broader market is also watching for regulatory responses, particularly in Europe, where IP enforcement is evolving rapidly. With the Unified Patent Court becoming a central venue for such disputes, the Arbutus case could set a precedent for similar biotech IP battles. and its underlying financial fundamentals will likely remain key indicators for assessing its long-term stability and investor sentiment.

Investor sentiment appears divided, with some viewing the legal challenges as temporary and not reflective of the company's core therapeutic innovations. Others, however, see the patent revocation as a significant hurdle, particularly if it leads to broader IP erosion in the European market. In the near term, Arbutus must balance its legal efforts with continued research and development in its HBV pipeline. The company has also been exploring potential licensing deals, which could provide a secondary revenue stream while the appeal process is ongoing.