Isis Pharmaceuticals has been named as a defendant in an intellectual property lawsuit filed by biopharmaceutical company Gilead Sciences against Merck related to a novel hepatitis C therapeutic.
The litigation relates to Gilead's sofosbuvir, a once-a-day oral nucleotide analogue inhibitor that is currently under review with the US Food and Drug Administration. According to a document filed with the US District Court hearing the case, Merck believes two of its US patents, which were developed in collaboration with Isis, are required for the drug's commercialization.
Merck recently offered non-exclusive rights to the patents — 7,105,499 and 8,481,712 — in exchange for a 10 percent royalty on sofosbuvir.
In a preemptive lawsuit seeking to have the IP declared invalid, Gilead argued that Merck had been following the development of sofosbuvir by Pharmasset, which was acquired by Gilead for $11 billion in late 2011, and viewed the compound as a threat to its own recently approved HCV treatment boceprevir.
As such, Merck amended the claims within the '499 and '712 patents during their prosecution at the US Patent and Trademark Office "in an attempt to cover compounds useful for treating HCV infection and/or methods of treating HCV infection" that were the subject of patent applications related to sofosbuvir, Gilead claimed in its lawsuit.
The move was an "attempt to exclude Pharmasset from the market or extract royalty payments in relation to potential future Pharmasset products," it added.
Both patents are entitled "Nucleoside Derivatives as Inhibitors of RNA-dependent RNA Viral Polymerase," and claim the use of nucleoside derivatives to inhibit HCV replication in order to combat the virus. Both Isis and Merck are listed as assignees of the IP.
The patents stem from an alliance forged between the companies in 1998 to discovery drug candidates for HCV.