Petitioners filed their reexamination request as public comment on WARF’s U.S. patent position became increasingly negative. Reexamination at the USPTO is a procedure by which it considers whether patent claims should have been granted in view of prior art not considered before the claims were initially granted or prior art already on the record that was not considered fully.
Reexamination of the WARF ESC patents was requested on the basis of three papers published between 1982 and 1990 that detailed a process for deriving embryonic stem cells from nonprimate mammals. Two of the papers were not considered at all by the examiner who first allowed WARF’s patent claims, while the third was only considered during prosecution of one of the patents.
In addition, Jeanne Loring, Ph.D., of the Burnham Institute, a well-respected and world-renowned stem cell research scientist, submitted a statement that she and others in the field regarded the nonprimate ESC derivation papers as making derivation of primate ESC possible. She also provided laboratory records to the USPTO evidencing efforts to derive primate ESC using the methods described in the nonprimate papers before the WARF patent applications claiming those methods as applied to primate cells were filed.
At least initially, the USPTO appears to have agreed with the petitioners’ argument that the prior art, including the nonprimate ESC derivation papers, suggested a method that could, as demonstrated by Dr. Loring’s research, be so readily applied to primate cells as to render WARF’s patent claims obviously unpatentable.
While an initial rejection of the claims by the USPTO in any patent application is not uncommon, a situation where the examiner is clearly second guessing the original decision to issue a patent does not bode well. WARF will have an opportunity to submit a response to the USPTO in the coming months and following that, it will also have an opportunity to appeal any final ruling. In the meantime, the hESC research community is cautiously optimistic that one of the highest perceived barriers to progress in this field may ultimately be removed and investors may be more willing to support stem cell companies and research in the U.S.