European Patent Office revokes CRISPR patent of the Broad Institute


European Patent Office revokes CRISPR patent of the Broad Institute – another warning on the assignment of priority rights 



On 17 January 2018, on the second day of oral proceedings during opposition, the EPO revoked one of the patents covering the CRISPR/Cas9 technology.





The CRISPR/Cas system is a prokaryotic immune system designed to destroy foreign genetic material, such as from bacterial viruses. If foreign DNA is captured, part of it is retained in Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) in the prokaryote genome. Those parts will generate guide RNA that targets CRISPR-associated proteins (such as Cas9) towards foreign DNA with the same sequence. Modification of the CRISPR/Cas9 system produced a gene editing tool that, compared to earlier techniques, is much more precise and does not leave gene editing traces in the resulting genome. It is considered to be one of the most promising breakthrough technologies in the field of biotechnology.

Largely credited for the establishment of the current CRISPR/Cas9 technology are Doudna and Charpentier from the University of California Berkeley (US) and the University of Umeå (Sweden) on the one hand and the groups of Zhang and Church from the Broad Institute of MIT and Harvard (US) on the other hand. Doudna and Charpentier produced a modified Cas9 system that could be used to target any DNA sequence for cleavage. Zhang and Church transformed the prokaryotic work towards eukaryotic (human) cell cultures. Since the identification of the CRISPR/Cas9 technology, entities backing the various inventors have entered in several patent disputes. The Broad Institute has been one of the most active patent filers and secured, among others, a European patent on its CRISPR/Cas9 system in 2015. The patent (EP 2 771 468 B1) was opposed by nine opponents and the Opposition Division announced its decision to revoke the patent as a whole on the 17th of January.


A core element in the opposition was the entitlement to priority which revealed an Achilles heel in the European patent.


The international patent application, upon which the European patent is based, claimed the priority of twelve US provisional applications. Scientific articles, one from the group of Church, on the technology were published between the second and third priority date. As was common for US applications at the time, the inventors were named as co-applicants of the priority applications. This lead to inventor Marraffini being a co-applicant of the first and second priority applications. Mr. Marraffini was associated with and had assigned his rights to the Rockefeller University, which is not named as co-applicant of the international patent application.


However, in Europe, the case-law of the EPO’s Boards of Appeal specifies that, if applicant of the priority application and later application differ, the right to priority must be validly transferred to the final applicant before the filing of the later application (T 62/05 and T 788/05). If the priority application has been filed by multiple applicants, each of them must be either co-applicant on the later application or must have transferred his right to the priority claim to one of them (e.g. T 382/07). The validity of the transfer has to be determined under the applicable national law (see T 517/14 for a detailed analysis).


In the current case, the question to be answered under the established case-law was if Mr. Marraffini or his successor-in-title, the Rockefeller University, had assigned the right to the first and second priority before the filing date of the international application. In view of the absence of evidence to that effect, the priority claims were held invalid. That in turn led to the scientific articles published before the third priority date becoming prior art and a consequential lack of novelty of the claims. As a result, the patent was revoked in its entirety.


The EPO approach may be considered as very strict and some commentators see it as having overly severe consequences for a “formal technical requirement”, especially since many other Broad patents may suffer from the same failure. The Broad Institute has already announced that it will appeal the decision.


We will keep monitoring the appeal proceedings and it will be interesting to see if the Broad Institute succeeds in overturning a long established EPO case-law. In any case, this event is an additional warning that, if there is a difference between the applicants of a priority application and the subsequent filing designating Europe, a valid transfer of the priority right should occur before filing the subsequent application. While several decisions of the Board of Appeal of the EPO indicate that such a transfer should be assessed in accordance with national law, it appears prudent to execute such a transfer in writing. The language of the assignment itself is also of importance and, preferably, mentions the priority right explicitly.


by Stijn LAGAERT, GEVERS European Patent Attorney









European Patent Attorney 





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