Cisplatin plus anti-PD-1 antibody enhanced treatment efficacy in advanced esophageal squamous cell carcinoma

Therapies for patients with advanced esophageal squamous cell carcinoma (ESCC) are limited and accompanied by dismal prognosis. Here we use ESCC cell line K30 and TE-1 to investigate the antitumor efficacy of cisplatin plus anti-PD-1 antibody. Enhanced antitumor effects and increased CD8⁺ tumor-infiltrating lymphocytes of combination therapy were observed in TE-1 cells bearing humanized mice model. Lower cell viability and more cell apoptosis were found in the combination therapy in vitro. We next analyzed clinical data from patients with advanced ESCC received cisplatin-based chemotherapy plus an anti-PD-1 antibody (Tislelizumab or Sintilimab) as first line therapy from two clinical trials (NCT03469557, NCT03748134). With the response rate of 81.8%, duration of response of 15.2 months, median progression-free survival of 15.5 months, median overall survival of 21.5 months and manageable toxicity in patients with advanced ESCC, we demonstrated that cisplatin-based chemotherapy plus anti-PD-1 antibody is an effective and safe option. We further confirmed sublethal cisplatin could induce PD-L1 expression in ESCC cells and cisplatin-treated ESCC cells suppressed the activation and function of immune cells while the addition of sintilimab prevented this process. These results highlight the effectiveness of cisplatin combining with anti-PD-1 antibody in patients with advanced ESCC, revealed its capability to promote the PD-L1 expression in ESCC cells and act synergistically with anti-PD-1 antibody to restore exhausted immune cells activities, thus providing a theoretical basis for further explorations in the mechanism of the combination treatment of cisplatin-based chemotherapy with immune checkpoint inhibitors in ESCC.