Tuesday, 6 September 2016

Sofosbuvir revisited - a chemical puzzle

I last wrote about the blockbuster drug sofosbuvir in February 2015, around the time when a few oppositions were being filed against Gilead's European patent for the drug. The oppositions are currently going through the usual procedures at the EPO, and oral proceedings have been scheduled for 4-5 October 2016. From a quick look at the preliminary opinion of the opposition division, it looks like the patent will be upheld. With ten opponents and a huge amount of material on record, however, it still looks like a Herculean task for the patentee.
Chemical structure of sofosbivir (Wikipedia).

In the meantime, however, I noticed a recent article about a claim being made in the US that a patent owned by the University of Minnesota is infringed by the drug. The article does not mention the patent by number, but after doing a bit of simple searching I think it could be US6475985, titled "Nucleosides with antiviral and anticancer activity", which was granted to the University in 2002 (and was, incidentally, not cited as prior art in the EP oppositions), considerably before the earliest priority date for the sofusbuvir patent in 2007. Claim 1 of this patent reads as follows:

There are other independent claims that are directed to a chemical compound, rather than to a therepeutic method, but claim 1 does seem to have at least the use of sofosbuvir within its scope. It is, however, a bit of a complicated puzzle to figure out whether it does. Can anyone confirm this?