AbbVie has filed a lawsuit in the US seeking to block Amgen from selling a biosimilar of its arthritis blockbuster Humira, the world's second-biggest selling drug.

In its patent infringement complaint, filed in the US Court for the District of Delaware, the biotech says its action arises from "Amgen's desire to reap the rewards of AbbVie's innovation".

"Whereas AbbVie has spent decades of research and vast resources on the development of Humira [adalimumab], Amgen seeks to copy AbbVie's work and ignore AbbVie's patents", it argues, and stresses "while the Biosimilar Price Competition and Innovation Act gives Amgen an abbreviated regulatory pathway for its biosimilar version of Humira, it does not give Amgen license to infringe AbbVie's patents".

Last month a US advisory panel voted 26-0 in favour of Amgen's drug, dubbed ABP 501, on the back of studies conducted in both moderate-to-severe plaque psoriasis and moderate-to-severe rheumatoid arthritis, which met their primary goals in showing clinical equivalence to Humira, as well as comparable safety and immunogenicity.

Humira, an anti-TNF monoclonal antibody, pulls in annual sales of nearly $15 billion across its range of indications for inflammatory diseases. While pricing data aren't yet available, Amgen's offering is expected to be significantly cheaper and thus has the potential to generate substantial savings for healthcare providers.