 According to the Annual Report of Cancer Registration in China 2014, lung cancer, gastric cancer, liver cancer and colorectal cancer have become the top 4 solid tumors with the highest morbidity and mortality rates. So far, the main treatment modalities for these tumors have been surgery, radiotherapy and chemotherapy. However, the effect of conventional therapy on advanced cancer is limited, tumor metastasis is the major cause of death in patients with advanced cancer. With the development of oncology and immunology in recent years, immunotherapy represents a novel path to obtain a durable and long-lasting response in cancer patients. 