Following our previous post, Gilead has released news that the USPTO confirmed the validity of another of its U.S Tenofovir patents.
This time it is US Patent No. 5922695 which covers the ester derivative of the Tenofovir compound. The Tenofovir patent that was earlier confirmed as valid by the USPTO was US Patent No. 6043230, a method for contacting the ester derivative with a cell. Neither of these patents claim the fumarate salt of Tenofovir that makes up the marketed formulation (Viread). However, the ester derivative patent does serve as a blocking patent to the end formulation.
US Patent No. 5922695 corresponds with Indian Patent Application No. 2076/DEL/1997. The Indian patent application is the subject of pre-grant oppositions by Cipla and HIV patient groups. The hearings for the Indian application are likely to take place shortly and will be watched carefully to see if the Indian Patent Office simply copies the USPTO decision despite the existence of s3d.
Indeed, as reported in another post, Brazil will also be watching developments at the USPTO given that it has initially refused the patent for Tenofovir Disoproxil Fumarate (TDF), which corresponds with US Patent No. 5935946. The USPTO has yet to issue its decision on the re-examination of US Patent 5935946. What is important to note is that the ester derivative patents of Tenofovir are not believed to have been filed in Brazil. Therefore, the current USPTO decisions should have no bearing on the Brazilian TDF patent application.
The USPTO has yet to update the case files for these patents, so at present it is not possible to review its reasoning for re-validating the patents. As soon as the decisions become available, we will post them here.