Vacating a district court’s obviousness determination, the U.S. Court of Appeals for the Federal Circuit explained that the district court misapplied the law of inherency.  Par Pharm., Inc. v. TWI Pharms., Inc., Case No. 14-1391 (Fed. Cir., Dec. 3, 2014) (O’Malley, J.).

Par obtained patent claims directed to a method of increasing body mass in human patients suffering from anorexia, cachexia or loss of body mass by administering a nanoparticle formulation of megestrol.  Par’s claims further required that the nanoparticle formulation exhibit no substantial difference in Cmax (pharmacokinetics) when administered in a fed state versus a fasted state (i.e., the nanoparticle formulation reduced “food effects”).

When sued for patent infringement, TWi asserted that Par’s patent claims were invalid as obvious.  Both parties agreed that the prior art demonstrated the use of micronized oral suspensions of megestrol to treat anorexia and other ailments and that nanoparticles could be used in drug formulations.  Par asserted, however, that the food-effect differences were not known in the prior art.  Moreover, Par argued that, since the food effects were not known, a person of skill in the art would not have been motivated to combine the technologies.

The district court concluded that TWi had proven that it would have been obvious to prepare a nanosized formulation of megestrol.  While the district court concluded that the prior art did not explicitly disclose that the nanosized formulation would result in the claimed food effect differences, it nevertheless held that the food-effect differences were an inherent result of the nanosized formulation.  Accordingly, the district court held that the claims were invalid as obvious.  Par appealed.

The Federal Circuit acknowledged that inherency may supply a missing limitation in an obviousness analysis.  The Court cautioned, however, that inherency must be limited to circumstances where the limitation is “necessarily present” or is the “natural result” of the combination of prior art elements.  In this case, the Federal Circuit concluded that there was no evidence that the claimed food effect was necessarily present in the prior art or the natural result of the nanoparticle formulation of megestrol.  Accordingly, the Court vacated the obviousness decision and remanded for further proceedings on the inherency of reduced food effects in nanoparticle formulations.

The Federal Circuit next addressed the district court’s conclusion that TWi had proven a sufficient motivation to combine the known nanoparticle technologies and micronized megestrol.  Par argued that a person of skill in the art would not have known of the food effect differences, and therefore could not have been motivated to combine the technologies.  The Federal Circuit rejected Par’s argument, reasoning that the motivation to combine references need not be the same motivation that motivated the inventors.  While a person of skill in the art may not have been motivated to combine the technologies to abrogate food effect, a person of ordinary skill in the art may nevertheless have been motivated to combine the technologies to reduce viscosity and interpatient variability.

The Federal Circuit also held that the district court did not err in concluding that there was a reasonable expectation of success in combining the technologies.  While Par argued that the nanoparticle technology was new and unproven, the district court concluded that a person of skill in the art would have understood that making nanoparticles was not extremely difficult and could successfully be implemented in a number of drugs.  Moreover, the Federal Circuit acknowledged that the reasonable expectation of success for obviousness does not require absolute certainty for success.