Prometheus Laboratories asks Federal Circuit to revive Lotronex patent

California-based pharmaceutical company Prometheus Laboratories has asked the US Court of Appeals for the Federal Circuit to reinstate a patent covering its irritable bowel syndrome drug Lotronex (alosetron).

In May last year, the US District Court for the District of New Jersey invalidated the patent after it was challenged by Boehringer Ingelheim subsidiary Roxane Laboratories for obviousness and obviousness-type double patenting.

In 2011, Prometheus filed a patent infringement case against Roxane after it filed an Abbreviated New Drug Application (ANDA) seeking approval from the US Food and Drug Administration to make and sell a generic version of Lotronex.

The patent at suit, US number 6,284,770, was listed in the Orange Book with another Prometheus-owned patent, US number 5,360,800.

The ’770 patent had been delisted from the Orange Book in 2005. In 2007, after Prometheus acquired the Lotronex franchise, it sought a re-examination of the patent.

In 2010, after the US Patent and Trademark Office had issued a re-examination certificate for the patent, Prometheus was able to relist the ’770 patent in the Orange Book.

That same year, Roxane filed its ANDA. In its ANDA notice letter to Prometheus, Roxane included a paragraph IV certification that said the ’770 patent was invalid and unenforceable, and that it would not be infringed by the proposed generic.

Prometheus responded by suing Roxane for patent infringement at the New Jersey court in 2011.

The company said that Roxane’s notice letter did not address the re-examined claims of the ’770 patent, and instead was directed to non-existent claims of the patent. Therefore, Roxane’s paragraph IV certification was defective, Prometheus argued.

Prometheus asked the court to find that the letter was defective and null and void, and for a judgment that Roxane infringed the ’770 patent.

However, by May 2014, the court found that the ’770 patent was invalid due to obviousness and obviousness-type double patenting in light of the ’800 patent.

Neither Prometheus nor Roxane had responded to LSIPR’s request for comment at the time of publication.