Federal Circuit says Pfizer arthritis drug was double patented

The US Court of Appeals for the Federal Circuit has affirmed a lower court ruling which said that a reissue patent covering Pfizer’s arthritis drug Celebrex (celecoxib) was invalid for obviousness-type double patenting.

In a judgment issued yesterday, June 23, the court found that the patent at issue, RE44,048, was obvious in light of Pfizer’s patent 5,563,165, which covers compositions of celecoxib.

Pfizer had appealed against a March 2014 decision by the US District Court for the Eastern District of Virginia.

The ‘048 patent covers methods of administering arthritis drug Celebrex.

It is due to expire, with paediatric exclusivity, on December 2. Immediately after receiving the ’048 patent, which is a reissue of US patent number 5,760,068, Pfizer sued generic drug makers Lupin Pharmaceuticals, Teva, Mylan, Watson (now Actavis), and Apotex for patent infringement.

The generic companies responded by moving for a summary judgment, which the court granted.

The court considered a previous patent infringement action brought by Pfizer against Teva which also concerned the ‘068 patent. In that case, which was from 2008, the federal circuit found that the patent was invalid for obviousness-type double patenting in light of the ‘165 patent.

The ‘165 patent arose from an initial patent application that included three classes of claims: compound, composition, and method of use. That application was eventually split into separate patents, including the ‘165 patent.

In the previous case, Pfizer said that it was protected by a safe harbour provision that protects patents that issue on divisional applications from invalidation. The federal circuit disagreed, finding that Pfizer was not “shielded by the invalidating effect of the ‘165 patent”.

It said that the safe harbour is “limited to divisional applications”, and that the ‘068 patent “issued from a continuation-in-part, not a divisional application”.

Similarly in this case, the federal circuit found that the safe harbour provision does not apply, and ruled that the reissue patent was invalid.

A spokesperson for Pfizer told LSIPR that it may request a rehearing or appeal to the US Supreme Court.