Is Experimental Testing Necessary to Establish Inherent Obviousness at the PTAB?

Summary
At the end of last year, in Par Pharmaceuticals, the Federal Circuit affirmed the doctrine of inherent obviousness, but ultimately found that the defendants had not demonstrated that the claim limitation missing in the prior art was “necessarily . . . present, or the natural result of the combination of elements explicitly disclosed by the prior art.”¹ The court thus didn’t rule on the ultimate question of obviousness, but remanded to the district court “to determine if [the defendant] has presented clear and convincing evidence that demonstrates [the missing limitation] as claimed is necessarily present in the prior art combination.”² In this case, the Federal Circuit did not address what specific findings of fact would be sufficient to demonstrate inherency.

The PTAB recently addressed the doctrine of inherent obviousness, and also found that the evidence of inherent obviousness was insufficient. The PTAB, however, provided some guidance on the evidence needed to demonstrate inherency. Not surprisingly, an expert’s unsupported statements are insufficient to demonstrate that the missing element is inherent in the art. Instead, the PTAB emphasized that the petitioner should present, e.g., “testing data” showing that the prior art formulations would satisfy the limitations missing from the prior art.³ The PTAB also emphasized the absence of evidence from the prior art showing the missing limitation.

For some patent challengers, and for some types of claims, expert testing to show the inherent feature may not be a big obstacle. For other petitioners with limited resources, or if the experiments require testing on humans, for example, this would likely be impractical. In such instances, the petitioner may rely on the PTAB’s guidance that “the prior art” can be used to demonstrate the presence of the missing limitation. But this begs the question of, if the prior art discloses the limitation, then why would it be necessary to rely on the doctrine of inherency?

Given the PTAB’s limited tolerance of serial petitions, when challenging on the basis of inherent obviousness, challengers would be well advised to provide testing to show that the missing element is necessarily present in the prior art. Absent testing, a petitioner must be prepared to show that the element is the natural result of the combination explicitly disclosed by the prior art by some other means, such as using the prior art itself.

Brief Case Summaries
More details on the Federal Circuit case and the PTAB cases are below:

Par Pharmaceuticals
The claims at issue in Par Pharmaceuticals recite methods of using megestrol nanoparticles to “increase[e] the body mass in a human patient suffering from anorexia, cachexia, or loss of body mass.”⁴ The claims contain a “wherein clause,” called the “food effect limitations” by the Federal Circuit, which recite that there is no difference in the C_max of megestrol when the formulation is administered to the subject in a fed versus a fasted state.⁵

The Federal Circuit found that the prior art disclosed the use of nanoparticle technology in drug formulation, and one such reference listed megestrol as one of many preferred anticancer agents for use with this technology. However, the prior art failed to disclose a known food effect in megestrol. The defendants instead relied on inherency to establish this claim limitation in the prior art. The Federal Circuit found that the reliance on inherency was misplaced because there was “simply no findings of fact” addressing whether the food effect limitations are necessarily present in the prior art combinations.⁶

In its decision, the Federal Circuit validated the doctrine of inherency in the context of obviousness, but cautioned that it must be “carefully circumscribed.”⁷ In particular the court stated that “[a] party must . . . meet a high standard in order to rely on inherency to establish the existence of a claim limitation in the prior art in an obviousness analysis – the limitation at issue necessarily must be present, or the natural result of the combination of elements explicitly disclosed by the prior art.”⁸ The Federal Circuit remanded for the district court to determine whether such evidence existed.

PTAB
The four recent PTAB decisions addressing inherent obviousness are: IPR-2015-00005, 6, 7 and 8.⁹In IPR-2015-00006, the claims at issue are drawn to a composition that, when stored in a specific type of container exhibits “less than a 10% decrease in the concentration of nicardipine hydrochloride and (ii) a total impurity formation of less than about 3%.”¹⁰ The claims at issue in IPR2015-00005 and IPR2015-00008 are method of treatment claims and the administered composition has similar impurity limitations that are recited in the claims of IP2015-00006. Last, the claims in IPR2015-00007 are directed to methods of making a composition and the composition has similar as recited in the claims of IP2015-00006.

In the IPRs, the Petitioner asserted that the purity claim limitations were present in the art, and also that these limitations were an inherent feature of the compositions in the prior art. The Petitioner pointed to a prior art reference as teaching that the nicardipine hydrochloride solutions stored in the disclosed containers would maintain the stability over time. The Petitioner also argued that the stability limitations would have been met by following the teachings of the prior art.

Regarding the first argument, i.e., that the prior art teaches the stability limitations, the PTAB stated that the stability experiments conducted in the prior art were not conducted on compositions that fall under the claims, e.g., the concentration of active agent was not disclosed in the composition tested in the prior art. Regarding the inherency argument, the PTAB stated that the Petitioner failed to provide any independent testing data to support its inherency theory. All four petitions were subsequently denied.