The disclosure provides OX40L huIgG4 fusion polypeptide subunits comprising a human IgG4 Fc domain, a trimerization domain, and the receptor binding domain of Ox40 ligand, where the fusion polypeptide subunits can self-assemble into hexameric proteins. Also provided are methods of making fusion polypeptide subunits and hexameric proteins, and methods of use, e.g., treatment of cancer.本發明提供OX40L huIgG4融合多肽次單元,其等包括人類IgG4 Fc域、三聚域及Ox40配體之受體結合域,其中該等融合多肽次單元可自組裝成六聚蛋白。本發明亦提供製造融合多肽次單元及六聚蛋白之方法,及使用方法,例如,癌症之治療。