Federal Circuit: Jepson Claim Preamble Requires Written Description

The Federal Circuit has ruled that it is necessary to have a written description to support admitted prior art.

The case is In re: Xencor, Inc.

As the court explained,

Anti-C5 antibodies are monoclonal antibodies that bind to C5, a protein that performs complement activation. One specific type of monoclonal antibody, 5G1.1, can bind human C5 protein to block the progression of the complement cascade. A version of 5G1.1, called eculizumab, was used in clinical trials and had a known sequence. At the time of the patent application, eculizumab had been used to treat paroxysmal nocturnal haemoglobinuria (“PNH”), “a chronic blood disease caused by a defective enzyme that leads to a lack of protective natural complement inhibitors,” and was being studied in “the treatment of asthma and transplantation.” … Xencor additionally contends that anti-C5 antibodies have an anti-inflammatory effect and may be useful in treating various autoimmune disorders.

The patent application at issue in the case, US Patent Application No. 16/803,690, asserts that modifying antibodies with certain amino acid substitutions provides for longer staying power in the body and reduces the need for more frequent treatment.

There were two claims at issue on appeal: claim 8 (a Jepson claim) and claim 9 (a method claim). A Jepson claim is a type of patent claim that describes a new improvement to an existing invention. A method claim is a type of patent claim for a series of steps for performing a function or accomplishing a result.

Claim 8 of the ‘690 patent application recited:

In a method of treating a patient by administering an anti-C5 antibody with an Fc domain, the improvement comprising:…

Claim 9 recited:

A method of treating a patient by administering an anti-C5 antibody comprising: …

As the Federal Circuit explained,

Xencor … [appealed] a decision of the Appeals Review Panel (“ARP”)2 of the Patent Trial and Appeal Board (“Board”) rejecting the claims of its patent application as unpatentable for lack of written description. Specifically, Xencor [contended] that the Board and the ARP erred by construing part of one claim’s preamble as limiting and requiring written description for the Jepson claim preamble of another claim.

The Federal Circuit held that

the limiting preamble of a Jepson claim must be supported with sufficient written description, and what constitutes sufficiency varies depending on the knowledge of the pertinent person of ordinary skill in the art.

The court noted that

A patentee has the burden of providing written description; in a Jepson claim, that burden extends to the limiting preamble. We additionally hold that substantial evidence supports the Board’s finding that Xencor failed to provide adequate written description for its Jepson claim and for its other claim, the preamble of which we agree with the Board and the ARP is limiting.

The court thus affirmed the finding of the Board.

Xencor had argued that the method claim’s preamble of “treating a patient” was not limiting, that the preamble of the Jepson claim does not require a written description, and that, in the alternative, written description was satisfied for the preambles of both claims.

The court noted that the preamble of claim 9 recites “[a] method of treating a patient by administering an anti-C5 antibody comprising.” Thus, the first question for the court to address was whether the phrase “treating a patient” was limiting here.

Quoting a relevant precedent, the court said that

preamble language will also limit the claim if it recites not merely a context in which the invention may be used, but the essence of the invention without which performance of the recited steps is nothing but an academic exercise.

Here, the court agreed that the preamble term “treating a patient by” was limiting.

The court next addressed whether the ’690 application satisfied the written description requirement for “treating a patient.” It found that substantial evidence supported the ARP’s determination that it does not.

As the court explained,

To assess whether the written description support for “treating a patient” is sufficient, it is necessary to understand the scope of this limitation. The ARP acknowledged Xencor’s argument that “treating” does not require a particular effectiveness or result, and we agree. But while no specific amount of efficacy is claimed, and therefore no specific amount of efficacy requires written description support, the ARP also correctly observed that the application “does not define the term ‘treating,’ and it does not describe or provide any data associated with treating any patient with any disease or condition with any anti-C5 antibody, including an anti-C5 antibody with the claimed Fc modifications.”

The court found that the ARP had “comprehensively addressed” whether there was written description in the application for treating a patient:

The Specification does not describe what patients with what diseases or conditions can be successfully treated with an anti-C5 antibody possessing the claimed Fc modifications. Nor is there a single working example describing treatment of patients with a disease or condition with an anti-C5 antibody possessing the claimed Fc modifications. At best, the Specification lists three classes of diseases/conditions that might benefit from administration of various antibodies with an Fc modification, and lists various unmodified antibodies, including an anti-C5 antibody (5G1.1), that could be modified and used to that end.

This, said the court, was

inadequate to demonstrate possession of a method of treating any particular disease/condition with the claimed anti-C5 antibodies, let alone all diseases/conditions within the three enumerated classes.

The court agreed with the ARP that the specification does not include any example of treating a disease or condition with an anti-C5 antibody, and noted,

This is in comparison to other examples in the specification, such as a description of how to administer IgG antibodies in cancer treatment. Moreover, Xencor only presented evidence of trials that had already been discontinued when they were submitted, studying the use of eculizumab, which was not sufficient to show eculizumab was used to treat those diseases, let alone all diseases.

As for Claim 8, the question was “whether the preamble of a Jepson claim requires written description, and if so, whether Xencor’s application contained sufficient written description for said preamble.”

The court agreed with the ARP that a Jepson claim preamble requires written description:

In other words, the Jepson claim invention is the totality of what is set out in the claim, just as it is for a non-Jepson claim. The invention is not only the claimed improvement, but the claimed improvement as applied to the prior art, so the inventor must provide written description sufficient to show possession of the claimed improvement to what was known in the prior art.