The present invention is directed to novel IL-15/IL-15Rα heterodimeric Fc fusion proteins and uses thereof. The IL-15/IL-15Rα heterodimeric Fc fusion proteins can be administered to a patient to treat cancer. In some cases, the IL-15/IL-15Rα heterodimeric Fc fusion protein is administered in combination with a checkpoint blockage antibody such as a PD-1 antibody.本發明係關於新型IL-15/IL-15Rα異二聚體Fc融合蛋白及其用途。該等IL-15/IL-15Rα異二聚體Fc融合蛋白可投與至患者以治療癌症。在某些情況下,該IL-15/IL-15Rα異二聚體Fc融合蛋白與檢查點阻斷抗體諸如PD-1抗體組合投與。