In
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Freeman and Wood discovered the PD-L1 ligand;
- Wood discovered that PD-1/PD-L1 binding inhibits the immune response;
- Freeman and Wood discovered anti-PD-1 and anti-PD-L1 antibodies can block the pathway's inhibitory signal; and
- Freeman experimentally confirmed PD-L1 expression in tumors.
Thus, the district court concluded that Drs. Freeman and Wood should be added as inventors.
The Federal Circuit stated that a joint inventor must "contribute in some significant manner" but "need not contribute to all aspects of a conception." Moreover, "[i]nventorship of a complex invention may depend on partial contributions to conception over time." The court further noted that "publication of a portion of a complex invention does not necessarily defeat joint inventorship" but cautioned that an earlier publication could be a hazard to patentability.
Despite that the claims of one patent at issue were directed to using anti PD-1 antibodies and did not recite the PD-L1 ligand, the Federal Circuit agreed with the district court's finding that "knowing the structure and function of PD-L1 was essential to all the claimed inventions." The court reasoned that, "[u]nless one also knows that the PD-1 receptor binds to at least one ligand . . . such as PD-L1, there would be no reason to use anti-PD-1 antibodies." Thus, the claims "need not explicitly recite PD-L1 for research on PD-L1 to have a significant contribution to conception of the invention." Each of the remaining patents at issue recited using anti-PD-1 or anti-PD-L1 antibodies, and the court maintained that the "discovery of PD-1 in a vacuum was insufficient for conception." Thus, the Federal Circuit concluded that "Drs. Freeman and Wood's work linking PD-1 to its ligand and expression in tumors was a significant contribution to each of these patents' conception" and affirmed the district court's holding. Thus, a claim to a method of treatment may invoke inventorship for those who discovered the mechanism by which the treatment has an effect.
Inventorship continues to be a highly factually-dependent analysis. In the pharmaceutical development context, this case indicates that validating a new, and complex, target and connecting that target to a use could be significant contributions that may give rise to inventorship. Prudent record maintenance during the course of the research also could be critical evidence to demonstrate a contribution, particularly where research develops over time. Additionally, innovators should be cautioned that carefully drafted research agreements should be in place before any collaboration begins.
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