In a recent case, Endo Pharmaceuticals Solutions, Inc. v. Custopharm Inc., the Federal Circuit affirmed the validity of two patents listed in the Orange Book. This decision is significant because it illustrates the difference between prior art publication vs. prior use.
Below, some of the claim language is included, including two noteworthy claims under litigation — dependent Claim 2 and Claim 18:
Claim 1) A composition formulated for intramuscular injection in a form for single injection which contains 250 mg/ml testosterone undecanoate in a vehicle containing a mixture of castor oil and benzyl benzoate wherein the vehicle contains castor oil in a concentration of 40 to 42% vol.
Claim 2) A composition formulated for intramuscular injection in a form for single injection according to Claim 1, which contains 750 mg testosterone undecanoate.
Claim 14) A method of treating a disease or symptom associated with deficient endogenous levels of testosterone in a man, comprising the administering by intramuscular injection of a composition comprising testosterone undecanoate (TU) and a vehicle consisting essentially of castor oil and a co-solvent, the castor oil being present in the vehicle at a concentration of 42 percent or less by volume, the method further comprising:
(i) an initial phase comprising 2 initial intramuscular injections of a dose of TU at an interval of 4 weeks between injections, each dose including 500 mg to 1000 mg of TU, followed by (ii) a maintenance phase comprising subsequent intramuscular injections of a dose of TU at an interval of 10 weeks between injections, each dose including 500 mg to 1000 mg of TU.
Claim 18) The method of Claim 14, in which each dose contains 750 mg of TU.
Prior Art Publication vs. Prior Use
The patentee filed a suit in response to the submission of an Abbreviated New Drug Application (ANDA) with a Paragraph IV certification for the FDA approval of the corresponding generic. The district court concluded that the defendant had not proven invalidity under § 103 based upon some articles.
The Federal Circuit Decision
The Federal Circuit decision was authored by Judge Chen and joined by Judges Moore and Linn. On appeal, the Federal Court found that contrary to the position of the defendant, the vehicle formulation — specifically, 40% castor oil and 60% benzyl benzoate — was not inherently described in prior art articles describing the clinical studies.
In fact, the position of the defendant was that the vehicle formulation was inherent in the pharmacokinetic data described in the articles.
The Federal Circuit disagreed
According to the Court, the defendant had not demonstrated that it was possible to extrapolate the vehicle formulation from the pharmacokinetic data. Moreover, it would have been the defendant’s burden to prove otherwise.
Further, the Court stated that there were many more solvents described in the articles, and therefore a person of ordinary skill in the art would not have necessarily recognized the solvents described and claimed by the plaintiffs.
In this particular case, the difference with a routine case of “inherency” is that the underlined product was not known. Thus, inherency is precluded or very difficult to prove when the product at issue is not known in the prior art. This case outlines the difference between inherency from a prior art publication, which doesn’t necessarily describe the claimed product, versus public use, where the claimed product was used, and thus known.
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Silvia Salvadori, PhD