Patent applications for biotechnological inventions related to subject matter excluded from patentability often require the use of disclaimers to overcome objections raised in this regard. A recent case at the EPO’s Board of Appeal dealt with the question of using disclaimers for overcoming one of the four exceptions to patentability relating to biotechnological inventions, namely the use of human embryos for industrial or commercial purposes. In reaching its decision(T1441/13) on this case, the Board also addressed the question of when a method was first made available for culturing human embryonic stem (hES) cells.

The invention in question was directed to a method of culturing primate pluripotent stem cells (pPS), (including hES cells).  The Board of Appeal held that at the priority date, the method of culturing hES cells necessarily required the destruction of human embryos, excluding it from patentability according to R28(c) EPC.  In this decision, the Board confirmed that a method of producing hES cell cultures without destroying a human embryo in any production step was first disclosed by Chung et al. in 2008.

In more detail, the Examining Division had originally refused the application as being excluded from patentability in accordance with the provisions of Art. 53(a) EPC in combination with R28(c) EPC, specifically for being directed to uses of human embryos for industrial or commercial purposes.  However, a product derived from a human embryo, which did not involve its destruction, is allowable.  In the first auxiliary request of the appeal, the applicant attempted to overcome the objection over non-patentable subject matter by disclaiming from the method claim cells obtained by “means of a process in which human embryos are destroyed”.

However, the disclaimer was held to be unallowable as it did not meet the “remaining subject matter” test established by the Board of Appeal in case G2/10. This test requires that the subject matter remaining in the claim after the disclaimer must be – explicitly or implicitly – directly and unambiguously disclosed to the skilled person, using common general knowledge, in the application as filed.  In this instance, the subject matter remaining after the disclaimer related to a method of culturing pPS cells (including hES cells) derived, only and exclusively, from non-destructive methods.

The Board reasoned that the technique for isolating a single hES cell without destroying the embryo disclosed in Verlinsky et al. (2001) was not sufficient to carry out the method of the amended claim, which necessarily required the culture of any isolated hES cell to obtain an established culture of hES cells (derivation).  Rather, it was held that a method of producing hES cell lines without destroying a human embryo in any production step was only disclosed by Chung et al. in 2008, seven years after the priority date. Of note, the Board also ruled out the use of Klimanskaya et al. (2006) as basis for the availability of a technique for culturing hES cells without destroying human embryos.

The rejection of the Verlinsky and Klimanskaya publications means that unless any further relevant publications are discovered, the EPO will continue to treat the Chung et al. 2008 paper as being the first to disclose a method of producing hES cell cultures without destroying a human embryo in any production step.

Applicants should therefore note that the Board of Appeal’s decision in this case confirms that disclaimers in patent applications related to R28(c) EPC (the exclusion of uses of human embryos for industrial or commercial purposes from patentability) can only be validly applied in patent applications with an effective filing date after the publication of Chung et al. (7 February 2008).