As discussed previously, biosimilar applicants can gain significant strategic advantage by availing themselves of Patent Trial & Appeal Board (PTAB) patent challenge mechanisms. This week, the Board agreed to consider the patentability dispute over AbbVie’s HUMIRA® drug (IPR2016-00172) (here).

In the ‘172 IPR, Coherus challenged the patentability of AbbVie’s U.S. Patent No. 8,889,135 (“the ‘135 patent). The ‘135 patent is one of a series of patents covering various aspects of AbbVie’s HUMIRA® drug. HUMIRA®, one of the top selling drugs in the world, is used to treat numerous autoimmune diseases, including rheumatoid arthritis. Coherus announced its plans to file an application to market a biosimilar version of HUMIRA® in the second half of 2016 and filing IPRs against HUMIRA® patents is part of Coherus’s strategy for entering the market.

In the '172 IPR pending claims 1-5 (directed to methods of treating rheumatoid arthritis) were challenged as obvious over prior publications. The obviousness challenge was supported by the declarations of two scientists. AbbVie filed a preliminary patent owner response, but before the current rule change that would have allowed a responsive submission of new, expert evidence. In its response, AbbVie argued that Coherus’s position was flawed, and that the claims directed to Humira® were entitled to secondary considerations of non-obviousness.

At this preliminary stage, the PTAB agreed with Coherus, determining there is a reasonable likelihood that Coherus will show that the challenged claims are unpatentable. The PTAB noted that HUMIRA®’s commercial success is not commensurate with the scope of the claimed invention and thus may not overcome a determination of obviousness. Of course, this determination will likely be revisited once AbbVie is able to present evidence. Trial will proceed and the PTAB will make a final determination on the patentability of the claims within the next 12 months.

Coherus has lodged three additional IPR petitions at the PTAB, each directed against other patents in AbbVie’s HUMIRA® portfolio, IPR2016-00188, 2016-00189, and IPR2016-01018. Decisions on instituting trial in IPR2016-00188 and IPR2016-00189 are due by June 2016, and a decision on instituting trial in IPR2016-01018 will be issued in late fall.

News of the PTAB’s decision to institute trial in IPR2015-00172 caused AbbVie’s shares to drop 4% while Coherus’s shares gained 16%.