Tuesday, November 4, 2008

Federal Circuit Affirms Rejection of Claim Reciting Broad Genus of Monoclonal Antibodies For Failure to Satisfy Written Description Requirement

In In re Alonso, decided Oct. 30, 2008, the Federal Circuit affirmed a Board of Patent Appeals and Interference (“Board”) decision sustaining a written description rejection of a claim reciting a method for treating a neurofibrosarcoma (a type of cancerous tumor) using a human hybridoma-derived monoclonal antibody idiotypic for the patient’s tumor, i.e., a human monoclonal antibody capable of recognizing a particular epitope on that patient’s tumor. The Court held that the applicant’s disclosure of a single monoclonal antibody capable of recognizing one particular patient’s neurofibrosarcoma failed to adequately describe the recited genus purporting to encompass all human hybridoma-derived monoclonal antibodies capable of recognizing any patient’s neurofibrosarcoma.

The PTO routinely allows claims broadly reciting a genus comprising any isolated antibody capable of recognizing a specified antigen, without limiting the applicant to any specific antibody, or any specific epitope on the antigen (a single antigen typically has multiple epitopes, the specific and discrete region of the antigen bound by a given antibody). The PTO's revised written description training materials, published earlier this year, specifically states that the disclosure of a reasonably well characterized antigen satisfies the written description requirement with respect to a claim encompassing any isolated antibody capable of binding the antigen (see earlier post discussing the training materials). This is consistent with the Federal Circuit's decision in Noelle v. Lederman, which found that although the disclosure of a mouse antigen was insufficient satisfy the written description requirement with respect to a claim reciting a monoclonal antibody capable of recognizing the human counterpart of the mouse antigen, disclosure of the mouse antigen would provide adequate written description support for a claim broadly reciting any antibody capable of recognizing the mouse antigen. It is worth pointing out that under this approach, not only is it unnecessary for the patent applicant to disclose the structure of any monoclonal antibody falling within the scope of the claim, it is also unnecessary to disclose any information regarding the structure of the antigen. This is inconsistent with other Federal Circuit written description cases relating to gene sequences which have required some disclosure of chemical structure, i.e., Fiers v. Revel, UC v. Lilly, In re Wallach, and most recently Carnegie-Mellon v. Roche (discussed in an earlier blog post).

Alonso’s claim is distinguishable, however, because it is not directed to a single antigen. The PTO and Court found that this sort of tumor is characterized by “considerable antigenic heterogeneity,” both between patients and between metastatic sites within a single patient. It was this unpredictability with respect to the structure of neurofibrosarcoma antigens, and consequently the genus of antibodies recited in the claim, which was the basis for the written description rejection.

In Alonso, the PTO is employing the written description requirement as a doctrinal tool for limiting claim scope. Traditionally, the enablement requirement has played the primary role in policing claim scope. For example, in Amgen v. Chugai the enablement requirement was invoked to invalidate a claim broadly reciting genetic sequences encoding structurally undefined functional analogs of human erythropoietin, with the court essentially finding that the claimed genus exceeded the scope justified by Amgen's disclosure of a single gene encoding wild type erythropoietin. But in UC v. Lilly the Federal Circuit established a new role for the written description requirement, which I refer to as the Lilly written description requirement (LWD), and which many commentators have characterized as a super-enablement requirement. Indeed, the examiner rejected Alonso’s claim for failure to comply with both the enablement and written description requirements, treating the two doctrines as effectively redundant. The Board, however, only affirmed the written description rejection, reversing on the issue of enablement.

The examiners tandem enablement-LWD rejection was not surprising. For years, examiners have asserted violations of both the enablement and LWD requirements in rejecting what they perceive to be overly broad genus claims. But until recently, it was almost unheard of for the Board to explicitly overrule the enablement rejection while affirming on LWD. In fact, when I conducted a comprehensive study of LWD cases a couple of years ago I found only one case where the Board (or any court for that matter) reversed an enablement rejection but affirmed on LWD. That decision, Capon v. Esshar, was soundly reversed by the Federal Circuit on appeal. In its decision, the Federal Circuit stated that analysis for compliance with the enablement and LWD requirements are essentially coextensive, and suggested that it would rarely if ever be proper to find a claim enabled but nevertheless in violation of LWD. Thus, in this respect Alonso breaks new ground.

The Federal Circuit has repeatedly stated that an applicant can satisfy LWD with respect to a genus claim by disclosing "a representative number of species in that genus." In Alonso the court agreed with the board that, in view of the heterogeneity and unpredictability of the antigen, disclosure of a single species did not constitute a “representative number." However, the decision provides no guidance with respect to how many species would represent a representative number. In fact, although the "representative number" standard was set forth in UC v. Lilly in 1997, a cited repeatedly by the courts and PTO, to my knowledge neither the PTO nor the courts have yet to provide any useful guidance with respect to how to determine just how many species is necessary to constitute a "representative number.” In fact, I would argue that the test for compliance of a genus claim with LWD cannot be meaningfully distinguished from the test for enablement, as suggested by various panels of the Federal Circuit, e.g., Capon v. Esshar and Lizardtech.

Alonso exemplifies what I see as a recent emphasis in the patent office on carving out a substantial doctrinal role for LWD in policing claim scope, separate and distinct from the enablement requirement. Another example can be found in In re Kubin, another appeal to the Federal Circuit of a Board decision finding a claim enabled but nevertheless in violation of LWD due to the excessive breadth of the claim. The Federal Circuit's decision in Alonso does not bode well for Kubin, but the facts are distinct and we will have to await the Federal Circuit's decision in that case.