On August 24th, 2012 the Court of Appeals for the Federal Circuit affirmed a judgment of the United States District Court for the District of Delaware, holding that Princeton’s University’s U.S. Patent No. 5,344,932 was not invalid for double patenting. The ‘932 Patent is listed in the Orange Book against Eli Lilly’s pemetrexed product, ALIMTA.
The District Court Judge had rejected the defendants’ assertions that the ‘932 patent was invalid for obviousness-type double patenting in light of two earlier patents from the same family that claimed a structural analogue of pemetrexed (the ‘608 Compound) and an intermediate (the ‘775 Intermediate) capable of being converted into a number of antifolate compounds, including pemetrexed.
The ‘608 patent claimed a number of antifolate compounds that structurally differ from pemetrexed in that they possess a central thienyl group instead of a phenyl group.
The defendants, relying on the decision of the CAFC in Amgen v. Hoffman-La Roche, submitted that the proper double patenting analysis focused only on the difference between the ‘608 Compound and pemetrexed – elements common to both pemetrexed and the ‘608 Compound should not be considered. The CAFC rejected the defendants’ proposed approach and distinguished Amgen, holding:
Amgen expressly noted that “[t]his part of the obviousness-type double patenting analysis is analogous to an obviousness analysis under 35 U.S.C. § 103.” Id. And just as § 103(a) requires asking whether the claimed subject matter “as a whole” would have been obvious to one of skill in the art, so too must the subject matter of the ’932 claims be considered “as a whole” to determine whether the ’608 Compound would have made those claims obvious for purposes of obviousness-type double patenting.
The Court also held that the District Court had not erred in (a) finding that a person of skill in the art would not have substituted the thienyl group of the ‘608 Compound with the phenyl group of pemetrexed; and (b) discounting the defendants’ theory of bioisosterism that would have suggested to a skilled person to replace the thienyl group in the ‘608 Compound. In the context of chemical compounds, the CAFC reiterated that obviousness-type double patenting requires identifying some reason that would have led a chemist to modify an earlier compound to make the latter compound with a reasonable expectation of success. The CAFC gave significant deference to the District Court finding that there were multiple ways to modify the ‘608 Compound, and noted that the District Court did not find that replacing the thienyl group with a phenyl group “was the one, among all the possibilities, that would have been successfully pursued”. Absent any motivation to convert the ‘608 Compound to pemetrexed, the Court concluded that the asserted claims of the ‘932 patent were not invalid for double patenting over the ‘608 Compound.
The ‘775 Intermediate
The defendants’ theory of double patenting was that the ‘775 Intermediate could be used to make pemetrexed and that the ‘775 patent disclosed this use.
In support of its position, the defendants relied on several decisions of the Court of Appeal that had relied on the earlier patent’s specification in a double patenting analysis. The Court of Appeal confirmed that as a general rule, an obviousness-type double patenting analysis turns on comparing the claims of the earlier and later patents, and reliance in the earlier patent’s written description is permitted only to the extent necessary to construe its claims. The court distinguished the cases relied on by the defendants as representing a limited exception to this rule where an earlier patent claims a compound and discloses the utility of that compound and a later patent claims a method of using a compound for the particular use described in the earlier patent, holding:
That is not the case before us. Rather than a composition and a previously disclosed use, the claims at issue recite two separate and distinct chemical compounds: the ’775 Intermediate and pemetrexed, differing from each other in four respects. That alone suffices to undermine Teva’s argument regarding the ’775 Intermediate, for the asserted claims of the ’932 patent do not recite a use of the same compound, but a different compound altogether. The cited cases therefore do not govern.
Objective Indicia of Non-obviousness
The District Court, relying on a footnote in the Court of Appeals decision in Geneva v. GSK, had disregarded Lilly’s objective indicia of non-obviousness holding that “secondary considerations are not relevant to the analysis of invalidity for obviousness-type double patenting”. The Court of Appeals held this to be an error and, following its recent decision in In re Cyclobenzaprine Hydrochloride Extended-Release Capsule Patent Litigation held that objective evidence of non-obviousness should be considered when offered.
A copy of the Court of Appeal’s opinion may be found here.
A copy of the District Court’s judgment may be found here.