Provided are arginine depletion agents such as ADI-PEG for use in combination with cancer immunotherapies, for example, immune checkpoint modulators and T-cell adoptive immunotherapies, for treating various cancers. Also provided are related methods, compositions, patient care kits, and cell cultures.本發明提供精胺酸耗盡劑諸如ADI-PEG,其與癌症免疫療法組合使用以治療各種癌症,該等癌症免疫療法為例如免疫核查點調節劑及T細胞過繼性免疫療法。亦提供相關方法、組成物、患者護理套組及細胞培養物。