Celgene Corp on Thursday said the European Patent Office revoked a key patent on the company's flagship multiple myeloma drug Revlimid, a move that could shave a year or two from the medicine's exclusivity in Europe. REUTERS: Celgene Corp on Thursday said the European Patent Office revoked a key patent on the company's flagship multiple myeloma drug Revlimid, a move that could shave a year or two from the medicine's exclusivity in Europe.