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May 01, 2011 (Vol. 31, No. 9)

Difficulty in Patenting Improved Antibodies

Courts Increasingly Invalidating Claims for Lacking Written Description

  • Evidence of Possession Required

    In holding that Centocor’s asserted claims lacked written description, the Federal Circuit reaffirmed that an adequate written description is measured by whether the disclosure contained in the patent application reasonably conveys to one skilled in the art that the inventor possessed the claimed invention as of the filing date. While working examples and actual reduction to practice are not required for sufficiency under the written description requirement, the court stated that one of skill in the art should be able to “visualize or recognize” the claimed invention based on the specification.

    As established by past cases, possession of biologics may be demonstrated by reciting precise structural characteristics either explicitly (e.g., by listing the amino acid sequence of the antibody) or implicitly (e.g., by providing a deposit). The written description exemption for antibodies as outlined in the PTO Guidelines, which permits generic claims to antibodies against newly identified antigens, does not extend to claims to antibodies with specific properties such as minimum binding affinity or human variable region where such species have not been demonstrated to exist.

    The decision in Centocor demonstrates the increased willingness of courts to invalidate claims for lacking written description, as a separate requirement from enablement, especially in the biological arts. Thus, patent applications for improved biologics should be drafted with care to meet the current “possession” standard, for example, by explicitly reciting an antibody’s structure or observed activity. Additionally, multiple working examples of sequenced antibodies exhibiting the desired activity may support broader claims to antibodies with a percentage sequence identity or their encoding genes with variable nucleic acid hybridization. Furthermore, companies should consider process, manufacturing, and technology platform patents as additional means to protect their biologics, biosimilars, and bio-better innovations.

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