Chemical Obviousness Following KSR and Pfizer

In Takeda Chemical Industries, Ltd., et al. v. Alphapharm PTY, LTD., et al.. (No. 06-1329; Fed. Cir. 2007), a Federal Circuit panel affirms the district court’s decision, holding that structurally similar compounds are not obvious where the prior art fails to teach or suggest the newly claimed compound.

Citing the well-established line of case law concerning obviousness of structurally similar compounds, a panel maintains that in order to find a prima facie case of unpatentability, a showing that the prior art would have suggested making the specific molecular modifications necessary to derive the claimed invention is required. Alphapharma’s challenge to Takeda’s patent was insufficient because Alphapharma failed to show that the prior art suggested modifying the prior art compounds to derive Takeda’s claimed compound. This requirement, the panel notes, is consistent with the legal principles enunciated in KSR and Pfizer.

While the KSR Court rejected a rigid application of the teaching, suggestion, or motivation (“TSM”) test in an obviousness inquiry, the Court acknowledged the importance of identifying a reason that would have prompted the skilled artisan to modify the prior art. Thus, in cases involving new chemical compounds, it remains necessary to identify some reason that would have led a chemist to modify a known compound in a particular manner to establish prima facie obviousness of a new claimed compound. The panel also distinguished Takeda and Pfizer by noting that in Pfizer there was ample motivation to modify the prior art compounds to derive the claimed compound, whereas in Takeda the prior art provided no suggestion or motivation to select the compound at issue.