”PD-1 inhibitors are a new class of anti-cancer therapies, which are immunotherapy in cancer treatment, mainly by blocking the body’s immunosuppressive system to enhance the body’s own immunity against cancer. At present, this therapy is used in lung cancer, colorectal cancer. The research in various malignant tumors such as liver cancer is hotly underway. Here, I will tell you two real stories of PD-1 inhibitors against cancer. Mr. Li, who is entering his middle age, found a lump in his liver about 2 cm in diameter during a medical checkup, and the doctor told him that it was a malignant tumor, which is commonly known as “liver cancer”. The good thing is that the tumor is not big enough to be treated by surgical removal. The surgery was over, however, it did not end there. In 2012, Mr. Li’s liver tumor appeared again and he underwent a second surgery. The second and third years after the second surgery passed with peace and quiet. However, in the fourth year, 2015, bad luck struck again and a metastatic lesion of about 10 centimeters in size appeared in Mr. Li’s pelvis, which was once again removed by doctors for Mr. Li. The three surgeries severely destroyed the immune defense in Mr. Li’s body, and just shortly after the third surgery, Mr. Li developed multiple metastases in his liver and lungs, and his methemoglobin (a tumor marker for liver cancer) soared to more than 60,000. At this time, the doctor suggested him to take Doxylamine (a targeted drug for liver cancer), after taking the drug, the methemoglobin continued to rise and soared to more than 120,000, and the severe diarrhea caused by the drug made Mr. Li suffer. At this time, Mr. Li, who had been persistently fighting the disease, felt overwhelmed and felt that he might be coming to the end of his life ………. Just then, a doctor suggested that he could try PD-1 inhibitor immunotherapy, and through a friend in the United States, he purchased PD-1 inhibitor, and three weeks after receiving his first injection, Mr. Li’s diet and mental state had improved greatly. He was able to go out again with great energy, and he was a different person than he was three weeks ago. His AFP also dropped significantly to over 30,000. After the second injection, the AFP dropped to 20,000. Even more miraculously, the metastatic lung lesions were reduced by 50-60% (see Figure 1, Figure 2). Now, Mr. Li is receiving PD-1 inhibitor therapy every three weeks without any intolerable side effects, except for a transient increase in transaminases after the second cycle. Figure 1 Before PD-1 treatment, the tumor is marked in red Figure 2 After PD-1 treatment Mr. Zhao’s case is very similar to Mr. Yang’s. He found the liver tumor in June 2014 and had surgery to remove it, and the size of the tumor was not more than 3 centimeters at that time, which is small liver cancer. However, six months later, Mr. Zhao developed lung metastasis, and he had local treatment such as radiotherapy and radiofrequency, and also took doxorubicin, but his liver function deteriorated and his diarrhea was so severe that he could not continue taking it, during which his methemoglobin rose from 251 to 2890. on the advice of his doctor, he also underwent PD-1 inhibitor injection, and after 4 cycles of PD-1 treatment, the lung lesion shrank significantly (see Figure 3, Figure 4), and the methemoglobin also dropped to the normal range. Mr. Zhao happily told the doctor that the efficacy was so good that he could not believe that PD-1 inhibitor gave him a second life. Figure 3 Before PD-1 treatment, tumor marked in red Figure 4 After PD-1 treatment, tumor marked in red For more than a century, scientists have been convinced that the body’s immune system has great potential to fight cancer, they just did not know how to unleash this potential to fight cancer. Today, in addition to surgery, radiation therapy and chemotherapy for cancer treatment, immunotherapy has quickly become the fourth pillar of cancer treatment.