Abstract:

Esophageal cancer (EC) is a common aggressive tumor of the upper gastrointestinal tract. About 70% of patients have local or distant metastases at diagnosis, and the prognosis is poor. The current first-line therapy for patients with unresectable locally advanced EC is mainly radical chemoradiotherapy, and most patients recur within 1–2 years, with a low survival rate. The advent of immune checkpoint inhibitor therapy has improved this situation. The 2020 Edition of Treatment Guidelines for Esophageal Cancer was the first to add immune checkpoint inhibitor and chemotherapy as first-line treatment for patients with advanced EC. Programmed death 1 (PD-1) /programmed death-ligand 1 (PD-L1) inhibitors are currently the most common drugs in clinical trials for immunotherapy, and all have shown a better prognosis than conventional therapies in esophageal cancer, but the biomarkers used to screen the PD-1/PD-L1 inhibitor benefit population remain challenging. The biomarkers currently approved for PD-1/PD-L1 inhibitors include PD-L1 expression, microsatellite instability, and tumor mutational burden, but these biomarkers do not guarantee a definite benefit, and there are cases where the biomarkers do not achieve a significant benefit for patients. In addition, some patients may develop hyperprogressive disease after PD-1/PD-L1 inhibitor therapy, leading to worsening of the disease. Therefore, there is a need to improve the existing biomarkers and find higher predictive efficacy to screen the population to further enhance the benefit of immune checkpoint inhibitors in esophageal cancer.

Key words: Esophageal cancer, Immune checkpoint inhibitors, Biomarkers, Hyperprogressive disease