Addressing the issue of obviousness-type double patenting, the U.S. Court of Appeals for the Federal Circuit reaffirmed its earlier rulings that obviousness must be judged by whether the differences in subject matter between the new claim and the earlier claim are patentably distinct.  Eli Lilly and Co. et al. v. Teva Parenteral Medicines et al., Case Nos. 11-1561, -1562 (Fed. Cir., Aug. 24, 2012) (Lourie, J.). 

The appeal arose from the filing of an Abbreviated New Drug Application (ANDA) by Teva for regulatory approval of the anticancer agent pemetrexed.  At trial, Teva conceded infringement of U.S. Patent No. 5,344,932, but argued that the patent was invalid for obviousness-type double patenting based on two parent references—a predecessor to pemetrexed shown in U.S. Patent Nos. 5,028,608 and an intermediate in making pemetrexed shown in U.S. Patent No. 5,248,775.  The district court found the patent was not invalid, ruling that one of ordinary skill in the art would not have been motivated to change the portion of pemetrexed that differed from the compound shown in the ’608 and ’775 references and that, because the ’932 patent did not claim the use of the ’775 patent’s compound, the teachings of the ’775 patent were irrelevant to an obviousness-type double patenting analysis.

On appeal, the Federal Circuit affirmed the district court, ruling that proof of obviousness-type double patenting requires identifying some reason that would have led a chemist to modify the earlier compound with a reasonable expectation of success.  The Federal Circuit found that the district court’s factual findings in this regard with respect to the predecessor compound showed no clear error.  With respect to the precursor intermediate, the Court rejected Teva’s argument that because the precursor claimed in the ’775 patent is used to make pemetrexed, the ’932 patent claims a previously disclosed use for a patented compound.  Holding that for an obviousness-type double patenting analysis, only the claims of the prior art reference may be considered, not the specification itself, the court distinguished earlier holdings in In re Byck and Sun Pharmaceutical Industries, by finding that those cases involved situations in which the patentee attempted to claim a method of using a composition after disclosing the use in an earlier patent claiming the composition itself.  Here, the ’775 patent never claimed pemetrexed, only an intermediate along the path to synthesizing pemetrexed, and therefore Byck and its progeny did not apply. 

Finally, the panel rejected the district court’s refusal to examine secondary indicia of non-obviousness, finding that such evidence applied to an obviousness-type double patenting analysis as equally as any other obviousness argument.