The present invention includes an antibody or an antigen-binding fragment thereof that binds to cytotoxic T lymphocyte-associated antigen 4 (CTLA4), and further comprises an anti-human programmed death receptor 1 (PD-1) antibody or an antigen-binding fragment thereof. It relates to a stable formulation which may be contained. Also provided are methods of treating various cancers and chronic infections with the formulations of the present invention. [Selection diagram] Figure 1A本発明は、細胞傷害性Tリンパ球関連抗原4(CTLA4)に結合する抗体またはその抗原結合性断片を含み、抗ヒトプログラム死受容体1(PD-1)抗体またはその抗原結合性断片をさらに含有してもよい安定な製剤に関する。また、様々ながんおよび慢性感染症を本発明の製剤で処置する方法も提供される。【選択図】図1A