Pfizer, Inc. v. Watson Pharmaceuticals, Inc.

Animal tests of multiple animals are not required for enablement purposes of pharmaceutical patents, so long as the claim reflects varied effects on different species.

Opinion, (Andrews) Pfizer Inc. et. al. (“Pfizer”), brought suit for infringement of its anti-transplant injection drug, “Rapamune,” against Watson Pharmaceuticals Inc., et. al. (“Watson”). Waston conceded infringement, but claimed that the invention was obvious, and further asserted an enablement defense against Pfizer for failure to adequately describe the claimed subject matter. Rapamune contains the active ingredient Rapamycin, which is isomeric to another known compound with a similar effect known as FK-506. The key distinction was that, at the time of development, FK-506 was known only to have the immunosuppressive action required of anti-rejection drugs, and to be highly toxic. Prior art with respect to Rapamycin showed only isomeric similarity with FK-506, its immunosuppressive qualities, and that it was well-tolerated when taken orally. Rapamycin was not evaluated for its use in animal transplant models, its allograft acceptance, or its minimization of side effects. Therefore, the Court found that the differences in the prior art were sufficient to only show that a person with ordinary skill in the art (“PHOSITA”) would have been encouraged to try combination, and not expect success, in animal models, in a transplant context. Finally, Waston claimed that the written description would not enable a PHOSITA, because it lacked examples from many animals. The Court found that pharmaceutical patents are not required to have examples from many animal models, since Pfizser claimed that side effects vary in species. The patent’s validity was UPHELD.