Reference to a hybridoma does not limit a product-by-process antibody claim (T 0032/17)

Antibodies were recently awarded their own section in the latest EPO Guidelines for Examination (IPKat). This reflects the complex and specific case law pertaining to antibody inventions. One such complexity are the provisions provided for the definition of an antibody by reference to a deposited hybridoma (Rule 31 EPC). The recent Board of Appeal decision in T 0032/17 considered whether such a reference in an antibody product-by-process claim limits the claim to the antibody structures produced by the hybridoma. The Board also considered the novelty of a hybridoma product claim in view of the fact that the hybridoma was deposited before the application was filed.

Legal Background: Hybridomas

A hybridoma is an immortalised mouse cell line that produces a particular monoclonal antibody. The development of hybridomas allowed for the production of monoclonal antibodies at scale. Each hybridoma produces a unique, sequence specific antibody.  

These days, hybridomas have been largely replaced by techniques permitting the generation of humanised or human antibodies that are safer when used as therapeutics. None-the-less, patent law relating to therapeutic antibodies recognises the initial dependence of the field on hybridoma technology. In order to satisfy sufficiency requirements, an antibody may be defined in a patent application by a reference to a hybridoma that produces the antibody (EPO Guidelines for Examination, G-II- and Case Law of the Boards of Appeal, II-C-7.3). The hybridoma must be made available to the public in the form of a biological deposit, and referenced in the application as filed (Rule 31 EPC). 

Process step of "produced by a referenced hybridoma" does not limit a antibody product claim

In T 0032/17 the Board of Appeal considered whether a product-by-process claim, directed to antibodies produced from a number of hybridomas, was novel in view of a prior reference to the hybridomas. 

The relevant hybridomas were deposited before the priority date of the patent. The application as filed referenced the hybridomas and provided the deposit numbers (Rule 31 EPC). The patent application did not provide any information about the structure or sequence of the claimed antibodies other than by reference to these deposited hybridomas.

The hybridomas were also mentioned in a product catalogue pre-dating the patent application. The mention of the hybridomas in the catalogue was cited as an alleged prior use of the claimed antibodies. The novelty of the claims thus depended on whether the claims could be said to be limited to the specific antibody sequences produced by the hybridomas.  

The Board of Appeal found that the deposit information provided in the application as filed for the hybridomas did not in fact convey any technical information about the structure of the antibodies produced by the hybridomas, either explicitly or implicitly. As such, the claim could not be said to be limited by reference to these hybridomas. The Board therefore viewed the prior mention of the hybridomas as novelty destroying. 

Novelty of a hybridoma product claim

The patentee also filed an auxiliary request including a product claim directed to the hybridomas per se as opposed to antibodies produced by the hybridomas. The Opponent argued that such a claim also lacked novelty because the hybridomas were deposited before the application was filed. Particularly, the Opponent argued that the deposit of a hybridoma under Rule 31 EPC renders the hybridomas available to the public on the date of deposit.

The Board of Appeal noted that Rule 33(1) EPC provides that biological material (e.g. a hybridoma) "shall be available upon request to any person from the date of publication". As such, deposited hybridomas are made available to the public when the patent application is published. The Board noted the lack of any evidence that anyone had obtained a sample before the application in question had been published. The Board thus found that the public availability of the deposited hybridomas post-dated the filing date of the application, and that the depositing of the hybridomas before the priority date was not novelty destroying to the hybridoma product claim (But is a lack of evidence of disclosure the correct test for prior use? As we have recently seen, the test of prior use in the UK is the potentiality for public disclosure, IPKat). 

Final thoughts

The decision in T 0032/17 provides some key clarification on the nature of a deposit of biological material under Rule 33 EPC. According to the Board's decision in this case, mere reference to a hybridoma does not limit an antibody claim to a particular structure or sequence. Given the increasing difficulty of relying on functional antibody definitions for both novelty and inventive step, this decision will be disappointing for those few parties still relying on deposit information. 

Reference to a hybridoma does not limit a product-by-process antibody claim (T 0032/17) Reference to a hybridoma does not limit a product-by-process antibody claim (T 0032/17) Reviewed by Rose Hughes on Tuesday, June 01, 2021 Rating: 5


  1. The duly summoned opponents 1, 3, 4 and 5, were, as announced in advance, neither present nor represented at the OP.
    After the BA's final decision had been announced at OP, opponent 4 withdrew their opposition. As the final decision became effective immediately on its announcement, the above mentioned withdrawal did not change opponent 4's status as a party to the appeal proceedings.
    But if opponent 4 was not present, how could he withdraw his appeal after the decision was announced? Should it be 2 or did copy/paste make havoc?

    For the rest the decision of the BA is understandable. Functional claims are ok, but they need some substance, which is not the case here!

    1. No typo, opponent 4 has sent a letter withdrawing their opposition on July 6 whereas the OP had already taken place on July 2.

  2. "But is a lack of evidence of disclosure the correct test for prior use? As we have recently seen, the test of prior use in the UK is the potentiality for public disclosure, IPKat"

    And there are good reasons for this...
    Firstly, negative evidence is usually difficult to get. And secondly, if we extend this to sufficiency, there would be a lot of problems: "The patent is revoked because there is no evidence anyone got a sample and so no one was sufficiently enabled." This would not be right, imho, just as it is not correct for novelty.

  3. I wonder what the Board would have concluded if the opponent had provided evidence that a sample had been sent out early.

    If the deposit is made under the Budapest Treaty then any sample issued before publication could only have been due to an error at the depositary. So there shouldn't be any potential for prior use because the depositary shouldn't be sending out samples early, but what happens if the depositary makes a mistake?

    Surely the applicant is afforded some sort of protection against this kind of accidental disclosure? Obviously the EPO isn't a party to the Budapest Treaty but I always thought Rule 31 EPC was supposed to follow its spirit.


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