Arbutus Biopharma slips after Europe revokes key patent

Shares of Arbutus Biopharma ABUS.O fall 16% to $3.93

The European Patent Office revoked Arbutus' key ’254 patent after challenges from Moderna MRNA.O and Merck MRK.N

Arbutus says it disagrees with the outcome and plans to appeal once the written ruling is issued

Arbutus says the decision is based on an EPO‑specific "added matter" rule and warns that outcomes in its broader litigation remain uncertain

Jefferies analysts called the revocation "disappointing" and said overturning it on appeal will be "slightly tougher this time around"

ABUS owns the ’254 patent, an LNP molar‑ratio patent for lipid nanoparticles

Genevant, co-owned by Arbutus and drugmaker Roivant ROIV.O, asserts the patent in litigation

The ruling affects some of Arbutus' and Genevant's patent cases against Moderna in Europe, but does not impact their lawsuits in the U.S., Japan, Canada, or Unified Patent Court cases not involving this patent

ABUS rose 46% in 2025