Upon discovery of a novel biological target, an applicant may attempt to patent antibodies directed to the target, as such antibodies may have diagnostic and/or therapeutic applications. In the past, it has been possible to claim such antibodies in the US by merely stating that they are capable of binding the new biological target, and it was not necessary to characterise the structure or sequence of the antibody.

Recently, the U.S. Court of Appeals for the Federal Circuit decided in Amgen v. Sanofi 872 F.3d 1367 (2017), that claiming an antibody by reference to its target is insufficient to satisfy the requirements of 35 U.S.C. § 112(a), which requires that the specification contain a written description of the invention, and of the manner and process of making and using it.

The Court of Appeals found the previously-used “newly characterized antigen” test, which had been based on an example in USPTO-issued training materials and was noted in dicta in several earlier Federal Circuit decisions, contradicted the quid pro quo of the patent system whereby one must fully describe an invention in order to obtain a patent.

The USPTO has now issued a memorandum stating that, in light of the Court of Appeals decision, adequate written description of a newly characterized antigen alone does not provide adequate written description of a claimed antibody to that antigen, even when preparation of such an antibody is routine and conventional. Instead, patentees must disclose a sufficient number of species of antibodies, or adequately describe the characteristics of the genus of antibodies, such that the species may be recognized by those skilled in the art.

Under this new guidance, it is likely that patentees will be limited in the breadth of antibody claims that they can obtain in the US. This represents a divergence of US practice from that of Australia and Europe. In Australia, a claim to an antibody that specifically binds a new epitope is allowable where the applicant had disclosed the new epitope and shown that antibodies can be raised against it. This is because raising antibodies to that epitope is a principle that can be generally applied to produce antibodies over the whole scope of the claim. A similar principle applies in Europe.

The USPTO is preparing new examples for inclusion in the Manual of Patent Examining Procedure (MPEP) and Shelston IP will keep you informed of developments.