21 June 2013Americas

Federal Circuit holds Novo Nordisk patent invalid

The US Court of Appeals for the Federal Circuit concluded on June 18 that Novo Nordisk’s patent covering diabetes treatment repaglinide is invalid.

In the case’s third appearance before the Federal Circuit, the panel also reversed a district court finding that Novo’s patent was unenforceable due to inequitable conduct.

Repaglinide is an oral medicine used to treat type II diabetes. It is marketed as Prandin in the US.

Novo holds the patent for the drug, which covers a method of controlling blood sugar in diabetics using the repaglinide chemical in combination with the drug metformin.

In 2005, Caraco Pharmaceutical Industries, a Sun Pharmaceutical Industries subsidiary, made an Abbreviated New Drug Application (ANDA) seeking the US Food and Drug Administration (FDA)’s approval for a generic version of repaglinide.

Caraco seeked to market repaglinide as a therapy to be used on its own, or as a monotherapy, rather than in combination with metformin. It claimed Novo’s patent was invalid or, if valid, would not be infringed by a generic version of repaglinide.

Novo responded by launching a case at the US District Court for the Eastern District of Michigan, claiming Caraco infringed claim 4 of the patent, which covers the method of combining the use of repaglinide and metformin.

Caraco then submitted a counterclaim asserting the patent is obvious and unenforceable.

The district court agreed, finding it could be predicted that the benefit of combining the drugs would be at least equal to taking the drugs separately.

“It was apparently well-known in the art that two drugs having different mechanisms for attacking diabetes may be more effective than one, and so drugs were often tested in combination therapy after demonstrating effectiveness in monotherapy,” Judge Prost wrote in the Federal Circuit opinion.

The efficacy of the combination therapy had been demonstrated studies conducted by the inventors of Novo’s patent, though these studies had been criticised by the district court.

The lower court noted that other tests contradicted Novo’s findings, that it had failed to report these other tests, and that it did not report that for one of the studies, some of the results were not part of the original test protocol.

However, the Federal Circuit agreed with Novo that their omissions and representations were not material to the case, and reversed the initial district court decision.

In the opinion, Judge Newman agreed that Novo had not engaged in inequitable conduct, though dissented in part, deeming the company’s discovery of the synergistic effect of combining repaglinide and metformin patentable.

Andrew Williams, partner at McDonnell Boehnen Hulbert & Berghoff LLP in Chicago, said in the Patent Docs blog: “As Judge Newman pointed out, the lower court and the majority used the inventors’ exceptional intellect against them, because they had tried this particular combination.

“However, the proper legal test is not whether it would have been ‘obvious to try’ for the inventors, but rather whether one skilled in the art would have found the combination obvious to try.”

Williams told LSIPR that this particular case was unique as Prandin has three FDA-approved uses: one as a monotherapy, one in combination with thiazolidinediones (a class of diabetes drugs), and one in combination with metformin.

In 2005, when Caraco filed its ANDA, there were two patents listed in the FDA's Orange Book of approved drugs, one covering the repaglinide compound and one covering its use with metformin.

One of the patents expired while the case was pending, leaving Caraco with just one impediment to generic approval – the method-of-treatment patent. When Caraco sought a label ‘carve-out’ with the FDA to obtain approval for the two approved uses that were not patented, Novo drafted a new use code to cover all three uses, Williams explained.

“They probably did this because they knew that the FDA does not police the use code restrictions.  And, because the use code now covered all three uses, the FDA would not approve the carve-out.”

He added: “The current opinion will make it more difficult for patents covering drug combinations to survive invalidity challenges with regard to obviousness, even when the combination provides surprising and unexpected results."

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