Docket Nos. 2015-1131
DYK, WALLACH, HUGHES
January 13, 2016
Brief Summary: FC panel affirmed DC decision finding Pfizer’s US 6,573,293 and 7,125,905 not to be invalid in view of Mylan’s cited prior art and Pfizer’s showing of secondary considerations.
Summary: The 10/22/2014 Memorandum of the DC (1:10-cv-00528-GMS) found Pfizer’s US 6,573,293 (claims 5 and 21) and 7,125,905 (claims 1 and 2) relating to sunitnib malate, which is marketed as Stutent® for renal cell carcinoma, GI stromal tumors, and pancreatic neuroendocrine tumors, not to be invalid in view of Mylan’s cited prior art and Pfizer’s showing of secondary considerations. Sunitinib was synthesized as SU11248 by Sugen from SU5416 which was developed as an angiogenesis inhibitor. SU11248 was developed to target tumors directly. Mylan argued the claims would have been obvious because WO 99/61422 (the ‘422 Application) disclosed “a nearly identical analog of sunitinib and “the lead compounds available as of the priority date would have motivated one skilled in the art to derived the claimed sunitinib malate.” Mylan asserted that the ‘422 Application “instructs that each of the [approximately 1200] combinations will work, and therefore the ‘routine’ steps of going from dimethyl sunitinib to sunitinib [diethylamine] and finally to sunitinib malate were obvious”, relying on Merck (FC 1989) and Pfizer (FC 2007). The DC disagreed, however, finding the path from dimethyl sunitinib to sunitinib malate “would have required significant guesswork and variation of parameters”. Mylan’s proposed lead compounds were not accepted by the DC which found, e.g., “Mylan’s choice of SU5408…appears largely the result of hindsight” (as was the choice of dimethyl sunitinib, a “hypothetical compound listed as one of 1200 possible combinations in the ‘422 Application…the only hint that this compound could exist came from the ‘422 Application’s list of components” (“the patent challenger must point to more than mere structural similarity as a reason to select a compound as a lead” (Bristol-Myers, D. Del. 2013)). The DC also disagreed with Mylan’s proposed motivation to modify its proposed lead compounds, citing Daiichi Sankyo, FC 2010) (“Proof of obviousness based on structural similarity requires clear and convincing evidence that a medicinal chemist of ordinary skill would have been motivated to select and then to modify a prior art compound (e.g., a lead compound) to arrive at a claimed compound with a reasonable expectation that the new compound would have similar or improved properties compared with the old.”). The court was “not convinced that one skilled in the art-assuming dealkylation were recognized as a problem at all-would have expected the addition of diethylamine to solve the apparent problem” and “there is no explanation for why one skilled in the art would have found malate to be an obvious choice” (one expert had never selected malate, “one of the rarest salts in pharmaceutical compounds”; “unlike in Pfizer, there was nothing in the prior art to suggest…malate was one of a limited subset of salts to chose, or even that a salt form of sunitinib would be beneficial.”) The DC also found Pfizer’s evidence on secondary consideratons (unexpected properties, long-felt need and failure of others, and commercial success) to “support a determination of non-obviousness.” This decision was affirmed by the Federal Circuit.