AbbVie Inc.'s blockbuster anti-inflammatory medication Humira (adalimumab) was the world's top-selling patented drug in 2015. 

The primary US patent to Humira is due to expire in December this year but the path to market for biosimilars is not clear.  As reported here, AbbVie claims to have more than 70 follow-on patents to the drug's particular formulations, uses and methods of manufacture.  Unsurprisingly, these follow-on patents are being challenged by AbbVie's competitors.

One such challenge was made by Coherus BioSciences Inc against US 8,889,135, which is considered a key patent in the follow-on portfolio.  The patent, which was filed in 2002 and granted in 2014 (prosecution timeframes at the USPTO are another story), protects a specific Humira dosage regimen.  The granted claim reads: 

"A method for treating rheumatoid arthritis in a human subject, comprising administering subcutaneously to a human subject having rheumatoid arthritis a total body dose of 40 mg of a human anti-TNFα antibody once every 13 -15 days for a time period sufficient to treat the rheumatoid arthritis..."

Coherus had argued that determining this dosage regimen was merely “routine optimization of the therapy” and so the claimed invention was obvious. 

This week, the Patent Trial and Appeal Board decided to hear the challenge, meaning that they consider it to have a “reasonable likelihood of success”.  That news, which is not actually the revocation of the patent, still had a significant effect on both AbbVie's and Coherus's share prices. 

This story made the news because of the huge commercial success of Humira.  But there are also a couple of valuable lessons within it for companies without a blockbuster drug in their portfolios.  

Firstly, although this particular dosage regimen has been attacked for being “obvious”,  it is still the case that dosage regimens are patentable in the US, Europe and elsewhere.  If inventive effort has been made in determining that a particular dosage regimen is advantageous, or if the advantages are particularly surprising, then it is well worth considering patent protection for the regimen.

Secondly, the challenge in this case was in the form of an Inter Partes Review (IPR).  IPR has only been available since 2012, but it is already proving to be a much faster (and cheaper) way to challenge the validity of a competitor’s US patent than going through the Federal Courts.