Small changes to a drug’s active ingredient aren’t sufficient grounds to extend that drug’s patent, a panel of European judges has ruled.

Celgene subsidiary Abraxis Bioscience had argued that the patent on its anti-cancer therapy Abraxane (paclitaxel) should be extended because its combination of paclitaxel and nanoparticles—which the company dubbed “nab-paclitaxel” was a fundamentally different approach to treatment.

But judges on the European Court of Justice disagreed in a preliminary ruling, saying that the mere addition of nanoparticles didn’t change Abraxane’s “active ingredient” because the additions had no therapeutic effect.