Invalidity of Par Pharma's Patents on Megestrol Acetate Formulations Affirmed by Federal Circuit Court

In the early 1990s, Bristol-Myers Squibb (BMY) developed and patented Megace, a liquid pharmaceutical composition of megestrol acetate indicated for the treatment of anorexia, cachexia, or an unexplained weight loss. Par Pharmaceuticals (PRX) sought to design around the claims of BMS's patent, and introduced a generic version of Megace. In developing its product, Par discovered that flocculated suspensions of megestrol acetate could be formed using a much wider range of excipients and concentrations than those known to BMS. Through those efforts, Par obtained a series of patents on its flocculated suspensions, including U.S. Patent Nos. 6,593,318 and 6,593,320, the two patents-in-suit in this case.

Par won its paragraph IV challenge of BMS's patent in 2001 and, as the first ANDA applicant to file a paragraph IV certification, earned 180 days of market exclusivity for megestrol acetate oral suspension. In 2003, Par brought suit against Roxane Laboratories, a subsequent ANDA filer for megestrol acetate oral suspension, asserting that Roxane's formulation infringes the '318 and '320 patents. The district court granted Roxane's motion for summary judgment of invalidity for lack of enablement under section 112, paragraph 1. Last Friday, the Court of Appeals for the Federal Circuit affirmed (pdf) that decision.

The test of enablement is whether one of ordinary skill in the art can make and use the claimed invention without undue experimentation. Furthermore, under In re Wands (Fed. Cir. 1988), eight factors are relevant to the enablement analysis:

The quantity of experimentation necessary.

The amount of direction or guidance presented.

The presence or absence of working examples.

The nature of the invention.

The state of the prior art.

The relative skill of those in the art.

The predictability or unpredictability of the art.

The breadth of the claims.

The Federal Circuit cited two factors that were particularly relevant to the enablement analysis in this case: the unpredictability of the art and the breadth of the claims.

According to the court,

all the record evidence establishes that the art of making stable flocculated suspensions of megestrol acetate is highly unpredictable.

Moreover, the court concluded that the claims at issue

have an extraordinarily broad scope, allowing, for example, the choice of any surfactant in any concentration.

The court observed:

In this case, Par sought extremely broad claims in a field of art that it acknowledged was highly unpredictable, therefore, Par has set a high burden that its patent disclosure must meet to satisfy the requisite quid pro quo of patent enablement.

In reviewing Par's evidence of enablement, the Federal Circuit noted that the specification of Par's patents discloses only three working examples, utilizing only one new surfactant. Moreover, the court found the two declarations submitted by Par's expert witness to be conclusory and lacking "specifics as to the experimentation that would be needed to practice the entire scope of the claims." Additionally, the court characterized Par's evidence that Par's inventor was able to formulate the claimed composition with seven different surfactants as "merely colorable" evidence, failing to create a genuine issue of material fact as to enablement of the full scope of the claims.

Thus, the Federal Circuit concluded that each of the asserted claims of Par's patents is invalid for lack of enablement, and therefore affirmed the district court's grant of summary judgment.