Are Combination Drugs in Danger After the Federal Circuit’s Novo Nordisk Decision?

The Federal Circuit rendered a decision in Novo Nordisk A/S v. Caraco Pharmaceutical Laboratories, Ltd. on June 18, 2013, finding that a Novo Nordisk diabetes treatment patent involving the combination of the drugs metformin and repaglinide was an obvious combination of known diabetes treatment drugs, despite certain factual findings of the combination's unexpected results. Combination drugs, such as Novo Nordisk's metformin-repaglinide treatment for diabetes, have been increasingly found to be effective for treating a variety of ailments, but their development is typically incredibly expensive and time-consuming. This Federal Circuit decision could adversely affect investment in developing combination drugs, which in turn would affect the availability of these often very effective treatments. The decision also highlights the deference (or lack thereof) given to patent examiner findings during prosecution.

The case further involved an inequitable conduct dispute in which the Federal Circuit reversed the lower court's finding of inequitable conduct, but this dispute involves issues largely unrelated to the focus of this article.

Obviousness of Combination Drugs

With respect to the obviousness question before the Federal Circuit, the parties did not dispute that metformin and repaglinide were known as individual diabetes treatment drugs. Novo Nordisk and Caraco also did not dispute that combining drugs to treat disease was generally known at the time of the invention, or that it would have been obvious to try combining metformin and repaglinide. Instead, the obviousness inquiry focused on whether the particular combination of metformin and repaglinide achieved unexpected results, namely synergistic effects, so as to negate a finding of obviousness.

The Federal Circuit agreed with the district court's factual findings that: (1) the closest prior art was combination therapy using metformin and sulfonylurea, which is an insulin secretagogue; (2) the combination of metformin and the sulfonylurea class of insulin secretagogues was known at the time of the invention; and (3) repaglinide was known at the time of the invention as an insulin secretagogue. The court therefore concluded that the claimed metformin-repaglinide combination was obvious because it would have been reasonable for a person skilled in the art to use metformin with the known insulin secretagogue repaglinide, rather than the known insulin secretagogue sulfonylurea. In other words...