The purpose of this study is to evaluate the efficacy and safety of KC1036 versus investigator's choice of chemotherapy in patients with advanced recurrent or metastatic esophageal squamous cell carcinoma
Males or females aged 18 to 75 years;
Histologically or cytologically confirmed esophageal or esophageal-gastric junction squamous cell carcinoma;
Patient with advanced recurrent or metastatic esophageal squamous cell carcinoma previously treated with a PD-1 or PD-L1 inhibitor and at least second-line systemic therapy;
At least one measurable tumor lesion according to RECIST 1.1;
Any patient who is known to have untreated central nervous system (CNS) metastasis;
Other kinds of malignancies within 5 years;
Gastrointestinal abnormalities;
Cardiovascular and cerebrovascular diseases;