EPO Board of Appeal holds that synergy is not sufficient to establish inventive step

At the EPO, the presence of a synergistic technical effect is normally indicative of an inventive step. But following the advocacy of Hoffmann Eitle’s James Ogle and Joachim Renken, the EPO Board of Appeal in T1639/21 clarified that synergy alone does not imply inventive step.

This case related to the combination of an mRNA vaccine (e.g., against cancer) together with an antibody to counteract an “immune checkpoint”. Such immune checkpoints were known to prevent the immune system from attacking cancer. The distinguishing feature was that the antibody targeted a different immune checkpoint.

Based on the evidence in the patent, the Board concluded that the combined effect of the vaccine and the antibody was greater than the sum of the individual effects, and as such could be acknowledged to be synergistic. The same synergistic effect was known from the closest prior art, albeit with the distinct target for the antibody. The objective technical problem was therefore formulated as providing a further synergistic vaccine/immune checkpoint inhibitor combination.

The Board thus had to answer the question of whether the skilled person would have had a reasonable expectation of achieving a synergistic effect with an antibody targeting a different immune checkpoint.

The Board determined from the prior art, including common general knowledge, that the skilled person would have reasonably considered PD-1 as a promising immune checkpoint target for combination with cancer vaccines, including with mRNA vaccines as claimed. Critically, while the antibodies of the closest prior art and the claims acted by different mechanisms, no evidence was provided to suggest a direct molecular interaction between the vaccine and the antibodies. Instead, the synergy observed in the claimed invention was commonly known to be attributed to the indirect interaction outlined above: the antibody counteracted the immune checkpoint, enabling a more effective immune response to vaccination. Thus, the skilled person would also not have been deterred by the mRNA vaccine format as claimed, which was moreover already used in the closest prior art.

Other cited documents explicitly disclosed a synergistic effect between various different formats of cancer vaccines and antibodies against the same immune checkpoint as that claimed. Given this state of the art, the Board found that the skilled person would have had a reasonable expectation that combining the claimed vaccine and antibody would achieve a synergistic effect.

The Board thus distinguished this case from a number of earlier cases cited by the Patentee as suggesting that a "synergistic effect was per se unpredictable" and would therefore “automatically” warrant an inventive step. The Board also refused to refer a question to the Enlarged Board on this topic.

In conclusion, this important decision clarifies that synergy alone does not necessarily establish an inventive step. Depending on the facts, synergy may in some cases be reasonably expected and thus obvious based on prior art.