Under Art. 107, first sentence, EPC, an EPO decision can be appealed only by a party to the proceedings which gave rise to it. Concerning the entitlement to appeal of a transferee of a patent, see chapter III.O.1. "Party status as patent proprietor".
Source: http://www.epo.org/law-practice/legal-texts/html/caselaw/2019/e/clr_v_a_2_4_1.htm
Date retrieved: 17 May 2021