Description Prescription

| Brandon D. HupkaHans L. Mayer


Before Lourie, Dyk, and Stoll. Appeal from the Patent Trial and Appeal Board.

Summary: For drug patents, adequate written description of a broad genus claim requires (1) description of the outer limits of the genus and (2) a representative number of genus members or description of structural features common to genus members such that a skilled artisan can visualize or recognize genus members.

Gilead petitioned for Inter Partes Review of Minnesota’s prodrug patent. The parties agreed that the “Sofia” reference disclosed every limitation of each challenged claim. However, the parties disagreed about the priority date of Minnesota’s patent. In particular, Gilead argued that the claims in Minnesota’s application were not entitled to their claimed priority date and that the Sofia reference was therefore prior art to Minnesota’s patent. The PTAB agreed with Gilead, finding that the applications from which Minnesota claimed priority did not contain adequate written description support. Minnesota appealed.

On appeal, Minnesota argued that its patent application (from which it claimed priority) contained adequate written description because it had (1) ipsis verbis disclosure of the prodrug subgenus and (2) sufficient blaze marks to provide written description support. To the first point, Minnesota argued that ispsis verbis disclosure could be found by combining parts of various claims from its provisional application. The Federal Circuit disagreed, describing Minnesota’s proposal as a “maze-like” path with “each step providing multiple alternative paths,” and that this is not the same as a written description wherein “each of the optional steps had been set forth as the only option.”

The Federal Circuit also rejected Minnesota’s argument that the priority application provided written description support by providing “blaze marks,” i.e., indicia sufficient to guide one of skill in the art to the claimed invention. The Federal Circuit reasoned that even if the chief claim cited in Minnesota’s ipsis verbis argument “‘blaze[ed] a trail through the forest’ that runs close by the later-claimed tree, the priority applications ‘do [] not direct one to the proposed tree in particular, and do [] not teach the point at which one should leave the trail to find it.” In neither instance did Minnesota describe the genus members nor structural features sufficient to guide a skilled artisan. Thus, Minnesota failed to show it was entitled to the claimed priority, and the Federal Circuit affirmed the Board’s decision.

Editor: Paul Stewart