Chinta & Fratangelo LLP

Contact the author: Andrew Berks

Patents on rapamycin for restenosis held invalid for lack of enablement. Wyeth v. Abbott Laboratories, 720 F.3d 1380 (Fed. Cir. 2013).

Wyeth sued defendants for patent infringement. Defendants counterclaimed that the patents were invalid as not enabled and for lack of written description.  The specification disclosed only one rapamycin species (sirolimus). The alleged infringers marketed stent products with everolimus and zotarolimus, two rapamycin analogs. The district court adopted a broad construction of the term “rapamycin” as proposed by Wyeth, then held the claims non-enabled because the only species disclosed was sirolimus and because the chemical arts are unpredictable, because of the complexity of the invention, and because of limited knowledge of treatment of restenosis at the time of invention. Thus, practicing the full scope of the claims (i.e., with other rapamycin analogs besides sirolimus) required undue experimentation.

This finding was upheld by the Federal Circuit panel on appeal (Moore, Bryson, and Wallach, opinion by Moore). The claim scope is broad (id. at 1385). Wyeth attempted to broaden the background in the art (presumably to capture the infringing activity). But, the specification was silent on how to modify sirolimus in a way that would preserve utility for restenosis. Id. Such modification would require substantial experimentation. Id. The court found that the need to synthesize “at least tens of thousands of candidate compounds” would require undue experimentation. Id.

The opinion discussed factors for undue experimentation. Id. at 1386. Undue experimentation is a matter of degree, citing Chiron Corp. v. Genentech, Inc., 363 F.3d 1247, 1253 (Fed. Cir. 2004). A considerable amount of experimentation may be routine, but even routine experimentation is not without bounds. Id.

The court found that the specification was only an invitation for further research (“a starting point for further iterative research in an unpredictable and poorly understood field.”). Id. at 1386.

The district court finding that the patents were invalid as non-enabled was affirmed.

Comment. This case is interesting because patentees typically strive for broad claim construction to capture the activities of accused infringers, but here, the patentee was granted a scope of claim construction, at their own request, that put them in the territory of non-enabled subject matter.