For long-term litigants Sanofi and Amgen, it's a case of win some, lose some

In its patent infringement case against Sanofi’s (Euronext: SAN) new atopic dermatitis drug Dupixent (dupilumab), Amgen (Nasdaq: AMGN) has secured a win courtesy of the US Patent and Trademark Office’s Patent Trial and Appeal Board, who refused an inter partes review of its patent on the grounds that not enough evidence had been brought to invalidate it.

Sanofi and its development partner Regeneron (Nasdaq: REGN) want to cancel the Amgen patent, related to a failed asthma drug, which covers any "isolated human antibody that competes with a reference antibody for binding to human IL-4 receptor."

Amgen may have won this battle, but it's not clear who will the war. Sanofi has lodged a further two separate bids to review the patent in question, on which the US agency could deliver a verdict early next year.