Inter partes review (or IPR for short, which people tend to use in the industry) has become an important process for patents throughout the life science industry, but interestingly, so far we haven’t seen as many in the biosimilars space as one might expect. We expected that biosimilar applicants would look to use the IPR pathway to perhaps deal with patents they perceive as vulnerable, as they kind of clear the path to market. But so far, surprisingly, there have been fewer of those than we thought there would be.

In fact, pursuant to some information I saw on, we’ve only seen 4 biosimilar-related products have an IPR without a co-pending litigation. So, it doesn’t look like we’re seeing very much path-clearing. And with respect to the 25 or so biosimilar-related litigations that existed as of July 6, 2017, only 3 of them had involved a challenge to one or more patents that had been IPR-ed.

Overall, it appears that whether an IPR is used in a biosimilars context is, at the moment, more related to the parties involved then any type of significant industry-wide trend. For instance, Celltrion, Teva, and Pfizer have been very active with respect to Rituxan and Herceptin. And Coherus has been very active with respect to Humira.

One reason for this may be the issue of standing. Generally speaking, although you don’t need standing to file an IPR, you do need standing to appeal an adverse IPR decision. So some biosimilar companies might not want to risk going through the IPR process without that safety net of having an appeal available, so they wait to have standing prior to filing an IPR, which means they end up waiting for a litigation.

Now, another reason may be the sheer breadth of patents in the biologics space. Unlike small-molecule products that we’re used to, that are covered by the Hatch-Waxman Act, which may be covered by 1 or 2 patents or so, biologic products can have portfolios in the 10s or 100s. This makes it challenging for a biosimilar company to identify the most critical patents, which means it may be less productive to use the IPR process.

And the overarching concern with IPRs, basically in every context, is estoppel. A biosimilar company is unlikely to take their best shot at invalidating a patent in IPR where there is limited discovery, for instance, and the risk being of estopped from raising those arguments, and others that reasonably could have been raised in later district court litigation, may be a concern.


Ha Kung Wong has extensive experience litigating a wide variety of pharmaceutical cases, including those concerning biologics used to treat rheumatoid arthritis and autoimmune disorders. He also has extensive experience consulting, conducting due diligence and licensing pharmaceutical portfolios. Ha Kung has a B.S. in Biochemistry and a B.S. in Chemistry.


    Information contained in the Venable BiologicsHQ database relates to FDA-approved drug products listed in the CDER Purple Book or on the FDA website ( Information relating to FDA licensed products, FDA-approved indications, and aBLA and 505(b)(2) applications is obtained from public sources including the U.S. FDA website ( Information relating to litigations is given only for cases active from January 31, 2010 onward. Information relating to foreign biosimilar / biologics follow-on products approved in Australia, Canada, the E.U., Japan and South Korea is from public sources. Statistics graphics are compiled from information contained in the Venable BiologicsHQ database.


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