Invoking a newly minted equivalent disclosure doctrine, a panel of the US Court of Appeals for the Federal Circuit found that the written description requirement of § 112 was satisfied in the interest of arriving at a “flexible, sensible interpretation.” Nalpropion Pharm., Inc. v. Actavis Labs. FL, Inc., Case No. 18-1221 (Fed. Cir. Aug. 15, 2019) (Lourie, J) (Prost, CJ, dissenting).

Underlying its Contrave^® pharmaceutical product, Nalpropion owns three orange-book-listed patents related to methods of treating overweight or obesity in adults using a combination of naltrexone and bupropion and sustained release formulations thereof, which it asserted against Actavis in this abbreviated new drug application action.

The disputed limitation in the ensuing litigation was a wherein clause directed towards the dissolution profile for sustained-release naltrexone using the USP Apparatus 2 Paddle Method (USP 2). Actavis principally argued that claim lacked adequate written description support because the claimed dissolution profile was achieved using USP 2, but the supporting specification data was obtained using the different USP Apparatus 1 Basket Method (USP 1). Further, (1) both inventor and expert testimony demonstrated that USP 1 and USP 2 were not substantially equivalent and would thus produce different results; and (2) a person of ordinary skill would not appreciate that the sustained-release dissolution data using USP 1 was relevant to the claimed ranges using USP 2. Nalpropion argued that a person of skill would understand the inventors to have had possession of their invention irrespective of USP 1 or USP 2 because those methods are “substantially equivalent.” After the district court upheld the patents, Actavis appealed

The Federal Circuit affirmed in part, stating that the patents were not invalid for written description, but struck down the patents as obvious over the prior art. On the written description issue, the majority concluded that the district court did not clearly err because the dissolution data reported in the patent adequately supported the dissolution data ranges in the claim, and the dissolution profile related only to resultant dissolution parameters rather than operative claim steps. According to the majority, “[w]hile as a general matter written description may not be satisfied by so-called equivalent disclosure, in this case, buttressed by the district court’s fact-finding, and where the so-called equivalence relates only to resultant dissolution, we affirm the district court’s conclusion.”

Chief Judge Prost dissented, stating that the majority ruling did not comport with the law on written description, and that the majority had inappropriately added a new rule where a disclosure may satisfy the written description requirement when the relevant claim limitation recites only “resultant dissolution parameters rather than operative claim steps.”

Prost parted ways with the majority for three reasons:

• The USP 2 clause is limiting.

• The majority’s “substantially equivalent” rule is inconsistent with this court’s precedent.

• The district court clearly erred in finding that the written description includes a disclosure “substantially equivalent” to USP 2.

In Prost’s view, the claim in issue requires the sustained-release naltrexone to be formulated such that it obtains the recited dissolution profile using USP 2—not as generally measured by any method. Because the USP 2 clause is limiting and the original patent disclosure fails to literally or inherently disclose it, the written description inquiry should end there. “By concluding that the USP 2 clause is nonlimiting, the majority has sua sponte addressed a claim construction argument never presented to the district court,” Prost stated. Further, Nalpropion failed to present data or testimony showing that USP 1 and USP 2 were in fact substantially equivalent.

Prost further noted that teachings related to USP 1 may render methods using USP 2 obvious, but expert testimony that the two USP methods would not produce the same results was nonetheless relevant for written description.