Antibodies: The Challenges Facing Patent Applicants

Antibodies: The Challenges Facing Patent Applicants

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Antibodies are complex proteins generated by the body that bind to and optimally neutralize foreign antigens, namely, proteins that are foreign to the individual. Antibodies are increasingly being developed as therapeutics—biologics and biosimilars—to fight various diseases.

The structure of antibodies has been extensively studied and their two- and three-dimensional structures have been elucidated. Antibodies contain two heavy protein chains and two light protein chains that are associated in two dimensions in a Y-shaped structure. At the ends of the Y-shape are variable regions which are specialized to bind specifically to an antigen. These variable regions contain complementarity-determining regions (CDRs) that allow the antibodies to bind specifically to an antigen. Each light and heavy chain contains three such CDR regions.

While in the past, claims to antibodies which bind new antigens (i.e., the function of binding to a specific antigen) were found allowable, the application of recent case law [e.g., Abbvie and Amgen] has led to the granting of extremely narrow claims. Antibody claims may now be limited to the specific sequences encoding the CDRs of the disclosed antibodies, without inclusion of breadth associated with percent identity with such sequences, or additional functional language, such as affinity to which they bind their antigen, ability to block function of the antigen, etc. This limitation in scope is extremely important given the biosimilars that are currently being developed.

This panel will discuss the short-term and long-term implications of the application of Abbvie, Amgen and similar cases for biopharma companies engaging in the development of therapeutics. The panel will also discuss the current state of the enablement and written description requirements; namely, what needs to go into a specification in order to lead to the broadest possible claim coverage.