The U.S. Patent and Trademark Office (PTO) yesterday struck a blow against the human embryonic stem cell patents held by the Wisconsin Alumni Research Foundation (WARF). In response to a request filed last July by two public interest groups (ScienceNOW, 18 July 2006), the PTO ruled that three WARF patents based on the work of University of Wisconsin, Madison, stem cell researcher James Thomson fail to meet its criteria for non-"obviousness." But the battle isn't over, and WARF has vowed to defend its claims.
Many scientists have complained their work has been unfairly hampered by WARF's restrictive patents, which not only cover methods for deriving human embryonic stem (ES) cell lines but also the cells themselves. Last July, the Foundation for Taxpayer and Consumer Rights in Santa Monica, California, and the Public Patent Foundation in New York City, charged that the patents were invalid because they cover techniques that had already proven successful in deriving ES cell lines from mice. In what observers say is an unusually detailed opinion, the PTO examiners agreed with the petitioners.
Central to the PTO's reasoning was the question of whether success in generating mouse ES cells is so similar to generating primate ES cells that it constitutes "prior art." The examiners concluded that the earlier mouse work "anticipated" Thomson's achievements to the extent that they were "obvious" and therefore unpatentable. The PTO examiners also cited as prior art patent applications from a Texas company called Stem Cell Innovation based on work by Brigid Hogan of Vanderbilt University in Nashville, Tennessee, who derived pluripotent stem cells from human fetuses in the early 1990s.
The groups requesting the patent re-examination were jubilant. "Whoopee!" says Jeanne Loring, a stem cell researcher in San Diego, California, and longtime critic of WARF patent policies who worked closely with the plaintiffs. But the matter is far from settled. Patent re-examinations usually result in a preliminary rejection of the patents, says Cathryn Campbell, a patent attorney at the firm of Needle and Rosenberg in San Diego. WARF now has 60 days to file its response. After PTO's final decision, either party can then appeal to the Board of Patent Appeals and Interferences. WARF spokesperson Andrew Cohn says if all else fails, the foundation will go to the federal Appeals Court in Washington, D.C.