Objective  Several clinical trials have demonstrated that immunotherapy provides survival benefits to patients with esophageal squamous cell carcinoma (ESCC). Immunotherapy has been approved as second-line therapy for ESCC. However, the results from clinical trials do not fully reflect real-world situations due to the strict inclusion and exclusion criteria. This study aimed to analyze the current situation of immunotherapy in patients with ESCC and to explore the possible prognostic factors.

  Methods  Patients with locally advanced and metastatic ESCC who received immunotherapy at Peking University Cancer Hospital & Institute from January 2018 to November 2020 were included in the study. Patient characteristics, therapeutic regimens, clinical efficacy, adverse events, and progression-free survival (PFS) were analyzed.

  Results  In total, 33 patients with locally advanced and metastatic ESCC were enrolled in this study, including one patient with ankylosing spondylitis. All patients received programmed cell death-1 inhibitors, most commonly sintilimab (n=17, 52%). Twenty-five (76%) patients received combined immunotherapy including chemotherapy or anti-vascular targeted therapy. The numbers of patients receiving first-line, second-line, and third- or later-line therapywere 19 (58%), 10 (30%), and 4 (12%), respectively. The incidence rates of Grade 1-2 and 3-4 treatment-related adverse events were 64% (21/33) and 27% (9/33), respectively. Eleven (33%) patients experienced immune-related adverse events (irAEs), including rash (n=5), hypothyroidism (n=4), hepatitis (n=2), enteritis (n=2), reactive cutaneous capillary endothelial proliferation(n=2), and pneumonitis (n=1). Of these, four patients experienced irAEs that required immunotherapy for resolution, and three patients were treated with steroids. The total objective response rate was 36% (12/33). The median PFS was 9.17 months (95% confidence interval: 8.23-10.11). Multivariate analysis showed that the baseline of white blood cell count (P=0.010), lines of immunotherapy (P=0.004), and clinical efficacy (P=0.049) were independent factors related to PFS.

  Conclusions  Immunotherapy has good efficacy in patients with locally advanced and metastatic ESCC, despite diversity in drug selection and treatment models in clinical practice. Patients who received first- or second-line immunotherapy with clin-ical efficacy may achieve longer PFS. An elevated baseline of white blood cell count may be a poor prognostic factor. These findingswarrant further verification in larger sample populations in the future.