In Par Pharmaceutical Inc. v. Twi Pharmaceuticals, Inc., the Federal Circuit vacated and remanded the district court decision holding the Par claims at issue obvious. The district court decision rested in part on the doctrine of inherency, but Twi did not establish that the property at issue “necessarily must be present” in the product rendered obvious by the prior art. In reaching this decision, the Federal Circuit emphasizes the “high standard” required to invoke the doctrine of inherency in an obviousness context.

The Patent At Issue

The patent at issue was Par’s U.S. Patent No. 7,101,576, directed to methods of using megestrol:

  1. A method of increasing the body mass in a human patient suffering from anorexia, cachexia, or loss of body mass, comprising administering to the human patient a megestrol formulation, wherein:
    1. the megestrol acetate formulation is a dose of about 40 mg to about 800 mg in about a 5 mL dose of an oral suspension;
    2. the megestrol acetate formulation comprises megestrol particles having an effective average particle size of less than about 2000 nm, and at least one surface stabilizer associated with the surface of the megestrol particles; and
    3. the administration is once daily;

wherein after a single administration in a human subject of the formulation there is no substantial difference in the Cmax of megestrol when the formulation is administered to the subject in a fed versus a fasted state, wherein fasted state is defined as the subject having no food within at least the previous 10 hours, and wherein fed state is defined as the subject having a high-calorie meal within approximately 30 minutes of dosing.

(emphasis added)

The District Court Decision

The district court determined that the patent was invalid as obvious pursuant to a bench trial. As summarized in the Federal circuit decision, the district court found that “all elements of the claimed invention were disclosed in the prior art,” and that “even though the prior art did not explicitly disclose the food effect differences as claimed, … [t]he claimed pharmacokinetic parameters with respect to a food effect . . . are inherent properties of the obvious nanoparticulate formulation.”

The Federal Circuit Decision

The Federal Circuit decision was authored by Judge O’Malley and joined by Judges Wallach and Hughes.

According to the Federal Circuit decision, “[b]oth Par and TWi appear to agree that essentially all of the substantive limitations in the independent claims are present in the various prior art references identified by the district court. The point of contention is whether the specific food effect limitations are also disclosed in the prior art.” On that point, the Federal Circuit found no clear error in the district court’s conclusion that “there was no known food effect for megestrol in the prior art,” but disagreed that the doctrine of inherency could be relied upon to establish obviousness.

The Federal Circuit cited familiar language from In re Oelrich (CCPA 1981) for the proposition that “inherency must be limited when applied to obviousness, and is present only when the limitation at issue is the ‘natural result’ of the combination of prior art elements:

Inherency, however, may not be established by probabilities or possibilities. The mere fact that a certain thing may result from a given set of circumstances is not sufficient. If, however, the disclosure is sufficient to show that the natural result flowing from the operation as taught would result in the performance of the questioned function, it seems to be well settled that the disclosure should be regarded as sufficient.

As stated by the Federal Circuit:

A party must … meet a high standard in order to rely on inherency to establish the existence of a claim limitation in the prior art in an obviousness analysis—the limitation at issue necessarily must be present, or the natural result of the combination of elements explicitly disclosed by the prior art.

The Federal Circuit noted that the record before it might establish that “it may be true that a reduction in particle size naturally results in some improvement in the food effect,” but “the district court failed to conclude that the reduction in particle size naturally results in ‘no substantial difference’ in the food effect, as recited in claim 1.

The Federal Circuit therefore vacated remanded for the district court to determine “TWi has presented clear and convincing evidence that demonstrates the food effect as claimed is necessarily present in the prior art combination.

(The Federal Circuit was not persuaded by Par’s arguments regarding lack of motivation to combine, lack of expectation of success, teaching away, unexpected results, and long-felt need, and upheld the district court’s findings on those issues.)

Can The Function Be Parsed From The Composition? 

In reaching its decision, the Federal Circuit distinguished other cases where it had been admitted or shown that the property at issue was inherent to the claimed composition. But can the properties of a product be parsed from its components? When an applicant distinguishes a claimed composition from the prior art based on a functional property, an examiner may insist that the component(s) responsible for the property be recited in the claims. While such claim language may not always be required to satisfy the enablement and written description requirements, claims that rely primarily on functional language are vulnerable to challenge on those grounds.

On the other hand, I disagree with Kevin Noonan’s thesis that the Par claims raise subject matter eligibility issues under Prometheus. Unlike the Prometheus claims, the Par claims recite the administration of a novel megestrol formulation according to a specific dosing regimen. While non-obviousness of the Par claims was based on the “wherein” clause, that clause recites a specific result of the claimed method, whereas the “wherein” clause in Prometheus informed a relevant audience of the “need” to increase or decrease a subsequent dose.