The European Patent Office continued its housecleaning of beta-interferon process patents, last week revoking the Rentschler patent covering the production of recombinant beta-interferon from Chinese hamster ovary (CHO) cells.

Two weeks ago, the agency revoked Biogen Inc.'s "Fiers" patent under an opposition filed by Schering AG (see BioCentury April 14). The latest action, in response