US court invalidates one of two Gemzar patents
This article was originally published in Scrip
A US district court has granted a motion filed by Sun Pharma for partial summary judgement in its three-year battle over Lilly's Gemzar (gemcitabine HCl for injection) – invalidating Lilly's method-of-use patent (the '826 patent), which includes paediatric exclusivity and is set to expire in May 2013.
Sun wants to market a generic gemcitabine product before May 2013. The product, which has become standard therapy for advanced pancreatic cancer and some forms of lung, breast and ovarian cancer, had worldwide sales of around $1.7 billion in 2008.
Sun filed its motion in the District Court for the Eastern District of Michigan, and sought declaratory relief that the method-of-use patent is invalid over prior art, and alternatively that its generic version does not infringe the patent. Lilly countersued, alleging infringement.
In an August 17th decision, Judge George Carem Steeh ruled that the '826 patent was invalid. He also dismissed Lilly's counterclaim of infringement of the patent. Lilly plans to appeal against the ruling. It has been counting on the method-of-use patent for extending its US exclusivity.
Lilly says that the decision has no bearing on its compound patent for Gemzar (the '614 patent), which includes paediatric exclusivity and is set to expire in November 2010, and does not grant Sun the ability to immediately launch a generic gemcitabine product in the US.
According to court documents, Sun argues that Lilly obtained the '614 patent for the compound gemcitabine as an antiviral and anticancer, then improperly extended its monopoly over the compound by obtaining the '826 patent claiming a method of using gemcitabine to treat cancer. "Sun Pharmaceuticals argues that, if a compound claim fails to adequately disclose the patentable bounds of the invention, the court may look to the patent specifications of both patents to determine if there is an overlap of claim scope," the court said.
The court went on to state: "Lilly argues that its earlier '614 patent claimed the compound gemcitabine and its essential utility as an antiviral agent, and that the '826 patent claimed the new use of gemcitabine as an anticancer. Lilly asserts it disclosed the anticancer use in the '614 patent specifications to avert any 'best mode' challenges to the validity of the '614 patent, but relied on the antiviral utility of gemcitabine to obtain the '614 patent. Lilly maintains that, because the anticancer use of gemcitabine set forth in the '614 patent specification was unnecessary to support the '614 patent, the anticancer use was eligible for later patenting in the '826 patent. Lilly argues that the court may not rely on the earlier patent specification as prior art to determine whether the later patent resulted in double patenting."
The court stated that it was limiting its double-patenting analysis to a comparison of the claims in an earlier '612 patent to the claims in the later '826 patent – without relying on Lilly's motivations. It concluded: "Construing claim 12 of the '612 patent along with the other patent claims, Lilly claimed two utilities for the compound gemcitabine – antiviral and anticancer – and cannot now claim the same anticancer utility for the same compound." The court thus granted Sun Pharma's motion for partial summary judgement of invalidity of the '826 patent "to the extent the '826 patent claims the method of treating susceptible neoplasms [cancers] employing gemcitabine." It added that the claims are invalid as a matter of law under the doctrine of obviousness-type double patenting.
Sun indicated to Lilly in October 2006 that its ANDA contained a paragraph IV certification, alleging that the method-of-use patent was invalid. Lilly sued in a district court in Indiana in December 2006; a jurisdictional issue led to a change in venue from Indiana to a federal court in Michigan. Sun has a tentative approval from the FDA for its ANDA.
In a recent regulatory filing, Lilly said that Teva Pharmaceutical Industries' subsidiary Sicor and Mayne Pharma had also filed ANDAs claiming that the compound patent and method-of-use patent are invalid. A suit against Sicor has been scheduled for trial in September. In its filing Lilly noted: "Sicor's ANDAs have been approved by the FDA. However, Sicor must provide 90 days' notice prior to marketing a generic Gemzar to allow time for us to seek a preliminary injunction". Mayne has agreed to be bound by the results of the Sicor suit. In its approval letter to Teva, the FDA said that, as first filer, Teva is entitled to 180-day exclusivity, to begin from the date of commercial marketing.