Minimally Residual of Esophageal Cancer 001

(1) patients have been diagnosed or treated for another malignancy within 5 years prior to the start of this study (2) adenocarcinoma, mixed adenosquamous or other pathological types of esophageal cancer (3) any unstable systemic disease, including: active infection, uncontrolled hypertension, unstable angina, angina pectoris starting within the last 3 months, congestive heart failure (≥ New York Heart Association [NYHA] class II), myocardial infarction (6 months prior to enrollment), severe arrhythmia requiring medication, liver, kidney or metabolic disease (4) with known or suspected active autoimmune disease (5) previous treatment with anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137 or anti-CTLA-4 antibodies or any other antibodies or drugs that specifically target T-cell co-stimulation or checkpoint pathways (6) known history of testing positive for human immunodeficiency virus (HIV) or known to have acquired immunodeficiency syndrome (AIDS) (7) female patients who are pregnant or breastfeeding (8) other conditions deemed unsuitable for enrolment by the investigator