Clinical Trial Evaluating TQB6411 Injection in Participant s With Esophageal Cancer

Inclusion criteria

• Participants voluntarily participate in this study, sign the informed consent form, and demonstrate good compliance.
• Age between 18 and 75 years old (inclusive)
• Eastern Cooperative Oncology Group (ECOG) score of 0-1
• Expected survival >12 weeks
• At least one measurable lesion per RECIST v1.1
• Laboratory criteria(no hematopoietic growth factor correction within 7 days)：

• Hemoglobin (HGB) ≥90 g/L;
• Absolute neutrophil count (NEUT) ≥1.5×10⁹/L;
• Platelets (PLT) ≥90×10⁹/L;
• Total bilirubin (TBIL) ≤1.5×ULN;
• Alanine Aminotransferase (ALT)/Aspartate Aminotransferase (AST) ≤2.5×ULN (≤5×ULN if liver metastases present);
• Serum creatinine (CR) ≤1.3×ULNorcreatinine clearance rate (CCR) ≥50 mL/min;
• Histologically/cytologically confirmed recurrent or metastatic Esophageal cancer
• Failure/intolerance to prior PD-1/PD-L1 inhibitor plus platinum-based chemotherapy for recurrent/metastatic Esophageal Carcinoma (EC)
• Willingness to provide archived or fresh tumor tissue for biomarker analysis.
• Females of childbearing potential: Negative serum/urine pregnancy test within 7 days before enrollment and agreement to use effective contraception during and for 6 months post-study. Males: Agreement to use effective contraception during and for 6 months post-study.

Exclusion criteria

• Current or History of Other Malignancies
• Participants with any condition that may compromise venous access for drug administration or blood sampling are excluded.
• Participants with prior treatment-related adverse reactions that have not recovered to ≤ Grade 1 per CTCAE v5.0 criteria.
• Major surgical procedure or significant traumatic injury within 4 weeks prior to first dose, Scheduled major surgery during the study intervention period, Non-healing wound, ulcer, or bone fracture at screening
• Participants with any bleeding/hemorrhagic event ≥ Grade 3 (per CTCAE v5.0) occurring within 4 weeks before the first dose are excluded
• History of Thromboembolic Events within 6 Months
• Poorly Controlled Active Viral Hepatitis
• Participants with active syphilis infection requiring antimicrobial therapy are excluded
• Participants with any of the following pulmonary conditions are excluded: active tuberculosis, idiopathic pulmonary fibrosis (IPF), organizing pneumonia, drug-induced/radiation pneumonitis requiring treatment, symptomatic active pneumonia, or history of interstitial lung disease (ILD) requiring therapy
• History of Substance Abuse or Psychiatric Disorders
• History of Allogeneic Transplantation (Bone Marrow or Solid Organ)
• History of Hepatic Encephalopathy
• Major Cardiovascular Diseases
• Active or Uncontrolled Severe Infections
• Renal Failure Requiring Dialysis (Hemodialysis/Peritoneal Dialysis)
• History of Immunodeficiency
• Poorly Controlled Autoimmune Disease
• Poorly Controlled Autoimmune Disease & Epilepsy Requiring Treatment
• Poorly Controlled Diabetes
• Tumor-Related Symptoms and Treatment Considerations：

• Exclusion Criterion - Recent Anticancer Treatment (≤3 Weeks or Within 5 Half-Lives)
• Recent Use of National Medical Products Administration (NMPA) -Approved Anticancer Traditional Chinese Medicine (≤1 Week Prior to Treatment)
• Radiologically Confirmed Tumor Encasement of Major Vessels with High Bleeding Risk
• Uncontrolled Effusions Requiring Repeated Drainage
• Known to have spinal cord compression, leptomeningeal metastasis/carcinomatous meningitis, or symptomatic brain metastases with less than 4 weeks of symptom/imaging control.
• Known Hypersensitivity to Investigational Drug or Excipients
• Prior Treatment with Topoisomerase I Inhibitor-Based ADCs and/or Irinotecan Chemotherapy
• Prior Participation in Anticancer Clinical Trials Within 4 Weeks
• Investigator-Assessed Safety or Compliance Concerns