The EPO’s Board of Appeal has upheld the revocation of one of the Broad Institute’s key patents for CRISPR/Cas9 gene editing technology. This decision is the latest in the ongoing CRISPR patent battle.
Back in 2018, the EPO Opposition Division revoked the Broad Institute’s European patent EP2771468 for lack of novelty in view of intervening prior art. The key issue during the opposition proceedings was that one of the applicants listed as an applicant in the US priority application, had not transferred his priority rights to the Broad Institute. Instead, he had assigned them to Rockefeller University, which was not listed as an applicant in the later PCT application from which the European patent was derived.
The Opposition Division followed established EPO case law relating to priority entitlement, which supports the position that a priority application can only serve as a basis for claiming priority for a subsequent application that designates all applicants (or their successors in title) of the earlier application. Since the PCT application did not name one of the applicants named on the US priority application, the earlier filing date of the US priority application could not be considered the filing date of the European patent, and the priority claim was invalid. This loss of priority meant that a document published after the priority date became novelty-destroying prior art.
The Broad Institute appealed the decision, arguing that the term “any person” in Article 87 EPC (the rule governing priority at the EPO) should be interpreted to mean “at least one”, rather than “all”, and that since the priority application was a US filing, then the term “any person” should be interpreted according to US law. In the US, a priority application and subsequent application need only have one inventor in common.
During the course of the four day hearing, the Board of Appeal unexpectedly indicated that they were minded to refer questions on priority entitlement to the Enlarged Board of Appeal. However, the Board ultimately decided without referral, found the priority claim to be invalid, and dismissed the appeal.
Although consistent with the long-standing case law supporting the EPO’s practice on priority entitlement, this decision serves as a pertinent reminder that when filing a patent application claiming priority, it is important to ensure that when the group of applicants changes, at least the right to claim priority is assigned prior to the filing date of the application.