Senju Pharmaceutical Co., Ltd. et al. v. Lupin Limited et al.

Docket No. 2013-1630

March 20, 2015

Brief Summary: DC finding Senju’s reexamined composition and method claims relating to gatifloxacin eye drops with added EDTA would have been obvious affirmed.

Summary: This case relates to a generic gatifloxacin eye drop with added EDTA (“about 0.1% w/v”) encompassed by the reexamined claims 6 (method) and 12-16 (compositions) of Senju’s US 6,333,045. Seven prior art patents, “each containing some of the same chemistry as the claimed invention”, were alleged to render the claims obvious. Infringement suits decided before the same district court judge involving the same chemistry were also considered even though the issues and parties varied (Apotex and Allergan/Senju regarding Zymar®). The opinion noted “the combination of the chemistry and prior litigation has produced here a complex of arguments by both parties.” Senju argued the DC erred “by finding the prior art taught using 0.01 w/v% EDTA in an ophthalmic formulation would work to increase corneal permeability”; and (2) it erred by its “evidence of unexpected results unavailing”. Senju argued the DC did not consider the reexamined claims “as a whole” but the FC panel disagreed, finding the DC “stepped through the disputed claim limitations and pointed out where each is found in the prior art, along with reasoning for combining the prior art to reach the disclosure of the asserted claims” (noting it “focused on appellants’ own arguments, which highlighted key claim limitations”). The FC rejected Senju’s argument that the eight year gap between the prior art and the application filing date was “itself evidence of nonobviousness” as “unconvincing and improperly raised”. Senju also argued that the obviousness analysis of composition claims 12-16 should include consideration of “corneal permeability…because the claimed compositions embody the method of reexamined claim 6” but the FC disagreed because the claims did not include that limitation (Phillips, FC 2005; Leo Pharm. FC 2013). All of the limitations, except the inclusion of gatifloxacin as a substitute for other similar compounds (fluoroquinolones), were found to be in the prior art as were reasons to combine the references (ophthalmic quinolones compositions for toplical ocular formulations, using EDTA in the claimed percentages generally and to produce increased corneal permeability). Senju argued “nothing in the prior art reasonably suggested” the “method for rasing corneal permeability” of claim 6 but the FC concluded “[t]he asserted references demonstrate that one of ordinary skill in the art would have known that using 0.01 w/v% EDTA would result in an increase in corneal permeability” and “would [have led] one of ordinary skill to apply this teaching in conjunction with pre-existing quinolone formulations” (“the prior art actually teaches that adding EDTA to any polar compound will increase corneal permeability dose-dependently” and the DC’s reliance on Lupin’s experts vs. Senju’s was not erroneous). Two references were also found not to teach away since both found “success at higher concentrations [but] do not provide any indication that lower EDTA concentrations would not also work.” The FC panel also concluded the DC “properly considered evidence of unexpected results” and the increase in corneal permeability was “not unexpected or surprising, but…a product of routine optimization that would have been obvious” (even though the evidence had already been considered by the PTO during reexamination (“Ultimately, the district court properly concluded that the theories presented during reexamination proved too weak when challenged in a judicial forum to rise to the level” (Proctor & Gamble, FC 2009)). Judge Newman’s dissent argued “[i]n this crowded field, the specific combination and concentration here claimed is not shown, and the published scientific data lead away from the claimed subject matter” (increasing the corneal permeability of gatifloxacin “contrary to the prior art” which “points toward higher, not lower, concentrations of EDTA”).

This entry was posted in Functional limitations, Generics / ANDA, Obviousness, Reexamination. Bookmark the permalink.

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