To investigate the safe application of programmed death-1 (PD-1) monoclonal antibody in patients with recurrent liver cancer after liver transplantation.

Four patients with recurrent hepatocellular carcinoma after liver transplantation who still progressed after first-line targeted drug therapy were included in this study, and programmed death ligand-1 (PD-L1) expression was negative by immunohistochemistry of liver allograft puncture. Patients were treated with the PD-1 inhibitor Camrelizumab, 200 mg every 3 weeks, and the appropriate targeted drug combination was selected, while the immunosuppressive regimen was adjusted to mammalian target of rapamycin (mTOR) inhibitors in combination with mycophenolate mofetil. Blood routine, liver and kidney function, alpha-fetoprotein (AFP) and thoracic and abdominal imaging examinations were measured during follow-up, and changes in liver function and tumor parameters during follow-up were comprehensively analyzed to evaluate the efficacy and safety of PD-1 monoclonal antibody.

By February 2021, 2 of the 4 patients survived and were followed up for 17.3 and 15.3 months, respectively, during which they all received PD-1 monoclonal antibody for 6 times, with adverse reactions such as fatigue, diarrhea and hypertension, which were improved after symptomatic treatment and are still under continuous follow-up. In Case 1, the patient died 6.3 months after PD-1 monoclonal antibody treatment due to severe lung infection caused by compression of trachea and bronchus by pulmonary metastases (a total of 6 times of PD-1 monoclonal antibody treatment were performed during this period); in Case 4, the patient died 10.9 months after PD-1 monoclonal antibody treatment due to pneumonia, atelectasis and pleural effusion caused by compression of bronchus by pulmonary metastases (a total of 3 times of PD-1 monoclonal antibody treatment were performed during this period). Four patients were treated with PD-1 monoclonal antibody. However, AST levels were in a relatively stable state, and occasional fluctuations can also be quickly restored to normal by liver protection therapy; serum albumin fluctuated between 30 and 45 g/L; total bilirubin was in a normal level, and no jaundice occurred; AFP decreased to varying degrees in 3 patients. None of the patients developed significant rejection during the follow-up period. After treatment with PD-1 monoclonal antibody, 3 patients had stable disease assessed by the modified Response Evaluation Criteria in Solid Tumors, with a progression-free survival of 141 days; the other patient had a partial response assessed, with a progression-free survival of 180 days.

PD-1 monoclonal antibody is relatively safe in patients with PD-L1-negative recurrent hepatocellular carcinoma after liver transplantation under the effective immunosuppressive state of mTOR inhibitor combined with mycophenolate mofetil, but its effectiveness and long-term clinical benefit still need further observation.