Federal Circuit Distinguishes Between Enablement and Reasonable Expectation of Success

June 11, 2018

      In the recent UCB v. Accord opinion, a panel of the Federal Circuit drew a distinction between (i) the enablement of a patentee’s claims, and (ii) a reasonable expectation of success in an obviousness analysis. The majority found that the presumption of enablement for a claimed genus of compounds did not preclude a finding that there was not a reasonable expectation of success in creating a species falling within that genus.

      The patent in question (US RE38,551) recites in claim 1 the R-enantiomer of a compound having the formula:

wherein:
Ar is phenyl which is unsubstituted or substituted with at least one halo group;
Q is lower alkoxy; and
Q1 is methyl.

      A dependent pinpoint claim (8) recites the compound (R)-N-benzyl-2-acetamido-3-methoxypropionamide. This is the compound of claim 1 wherein Ar is unsubstituted phenyl, Q is methoxy, and Q1 is methyl. This compound is also known as lacosamide, an anti-epileptic drug marketed under the tradename Vimpat®.

      As part of Abbreviated New Drug Applications (ANDAs), several generic drug manufacturers alleged that claims relating to lacosamide in the ‘551 patent were invalid. One of the grounds for invalidity was nonstatutory, obviousness-type double patenting.

      The double-patenting theory relied on the claims of US 5,654,301. In particular, claim 39 of the ‘301 patent recites a compound having the formula:

wherein:
R is aryl, aryl lower alkyl, heterocyclic, heterocyclic lower alkyl, cycloalkyl or lower cycloalkyl lower alkyl, wherein R is unsubstituted or is substituted with at least one electron withdrawing group or an electron donating group;
R1 is hydrogen or lower alkyl and R1 is unsubstituted or substituted with at least one electron withdrawing group or at least one electron donating group;
A and Q are both O; and
one of R2 and R3 is hydrogen and the other is lower alkyl which is substituted with an electron donating group or an electron withdrawing group and n is 1-4.

      In the district court bench trial, it was undisputed that lacosamide falls within the broad genus of claim 39 of the ‘301 patent (i.e., if R were unsubstituted benzyl, R1 were unsubstituted methyl, R2 were hydrogen, R3 were methoxymethyl, and n were 1). The generic drug manufacturers argued that lacosamide was merely an obvious species of the genus claimed in the ‘301 patent. Thus, they argued that the claims directed to lacosamide in the ‘551 patent were invalid on the ground of obviousness-type double patenting over the claims of the ‘301 patent.

      However, the district court found that the claims of the ‘551 patent relating to lacosamide were patentably distinct from the generic claims of the ‘301 patent. Due to the broad classes of groups in claim 39 of the ‘301 patent, the court found that this claim encompassed thousands, if not millions, of possible combinations.

      The district court found that a person of ordinary skill in the art would not have had a reasonable expectation that placing an unsubstituted benzyl at R or an unsubstituted methyl at R1 with a methoxymethyl group at R3 would have yielded an efficacious anti-epileptic drug. Quoting Otsuka (678 F.3d at 1298), the district court stated that in the context of drug development “‘predictability is a vital consideration in the obviousness analysis,’ including obviousness-type double patenting.”

      The Federal Circuit did not find clear error in the district court’s factual findings concerning the reasonable expectation of success. Thus, while acknowledging that “this is a close case,” the panel affirmed the district court’s conclusion that the claims directed to lacosamide in the ‘551 patent were patentably distinct from the claims of the ‘301 patent. Accordingly, the claims directed to lacosamide were not found to be invalid on the ground of obviousness-type double patenting.

      Interestingly, although somewhat buried in the opinion, the panel drew a distinction between (i) the enablement of a patentee’s claims, and (ii) a reasonable expectation of success in an obviousness analysis. The panel stated that

Appellants further argue that lacosamide falls within the broad scope of claim 45 of the ’301 patent, and is thus presumed enabled. Appellants argue that this presumption establishes a reasonable expectation of success as a matter of law. We disagree. Appellants do not cite any authority for the proposition that the presumption of an enabled genus of compounds precludes the district court from finding that there was no reasonable expectation of success of creating a species falling within that genus. Slip Op. at page 23 (emphasis added).

      The panel continued, stating that “such a result would have a chilling effect on genus claiming in the chemical arts as there would be double patenting in all chemical compound cases where a parent patent claims a genus.” Slip Op. at pages 23-24.

      Somewhat indirectly, these statements may provide ammunition to patent practitioners when arguing against obviousness during prosecution. Specifically, there are times when a practitioner may argue that an examiner’s obviousness rejection is deficient because of no reasonable expectation of success of modifying an applied reference. However, in so arguing, the practitioner may open himself to an enablement challenge by the examiner. That is, the examiner may allege that if there is no reasonable expectation of success of modifying the applied reference to achieve the features recited in the claims, then perhaps the claimed features are not enabled.

      If the examiner makes such an allegation, however, it may be useful to echo the panel’s statements in UCB v. Accord. That is, it may be useful to argue that enablement for a claimed genus of compounds does not preclude a finding that there was not a reasonable expectation of success in creating a species falling within that genus.

UCB, Inc. v. Accord Healthcare, Inc., No. 2016-2610 (Fed. Cir. May 23, 2018)