European patent EP 1 313 508 B1 claims the use of pemetrexed disodium in the manufacture of a medicament for use in a combination therapy together with vitamin B12 for inhibiting tumour growth. In the last six years, several courts throughout Europe have dealt with the question of whether medicaments containing a different salt or the free acid of pemetrexed infringe this patent by equivalent means. Most of the lower courts denied an infringement. However, the supreme courts went in a different direction: the UK Supreme Court (case no.  UKSC 48, judgment of July 12 2017) and the Swiss Federal Supreme Court (case no. 4A_208/2017, judgment of October 20 2017) found infringement under the doctrine of equivalence. The decision of the German Federal Supreme Court (case no. X ZR 29/15, judgment of June 14 2016) was only concerned with one aspect of the doctrine. However, in light of this decision, the German Higher Regional Court of Munich confirmed infringement by equivalent means in its judgment of May 18 2017 (case no. 6 U 3039/16).
In contrast to the numerous infringement proceedings, national court decisions regarding the validity of European patent EP 1 313 508 B1 – which was maintained as granted in the opposition proceedings before the European Patent Office – are rare. In the UK and Swiss proceedings mentioned above, validity was not challenged. Validity was challenged in Germany, but not in the above-mentioned proceedings. Due to the so-called bifurcated system, validity of a patent and patent infringement cannot be dealt with in the same proceedings in Germany. Lack of validity has to be raised in separate proceedings before the German Federal Patent Court (FPC). In July 2018, the FPC revoked the German part of EP 1 313 508 B1 (case no. 3 Ni 23/16 (EP), judgment of July 17 2018). The reasons for this decision were published in November 2018. According to the FPC, the combined use of pemetrexed disodium and vitamin B12 for inhibiting tumour growth is obvious in view of the prior art.
Presently, an appeal is pending before the German Federal Supreme Court. It remains to be seen whether the Federal Supreme Court will confirm the decision of the FPC or add still another twist to the pemetrexed case. Overall, the pemetrexed case with all its twists is reminiscent of a quote attributed to the baseball legend Lawrence Peter "Yogi" Berra: "It ain't over till it's over."
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