The purpose of this study is to assess the efficacy and safety of QL1706 plus lenvatinib in second-line therapy for patients with metastatic esophageal squamous cell carcinoma after progression on immune checkpoint inhibitor therapy

Inclusion Criteria:

1. Subjects participate voluntarily and sign informed consent.
2. 18-75 years, male or female.
3. Histologically or cytologically verified diagnosis of unresectable locally advanced or metastatic esophageal squamous cell carcinoma
4. Patients who have disease progression verified by imaging on standard first-line immunotherapy with anti-PD-1/PD-L1 antibodies
5. At least 1 measurable target lesion according to Response Evaluation in Solid Tumors (RECIST 1.1).
6. ECOG PS 0-1

Exclusion Criteria:

1. Presence of any active autoimmune disease or history of autoimmune disease (such as: autoimmune hepatitis, interstitial pneumonia, uveitis, enteritis, hypophysitis, nephritis, hyperthyroidism)
2. Those who are taking immunosuppressants or systemic hormonal therapy for immunosuppressive purposes (dose> 10 mg/day prednisone or other equivalent cortiremonial hormones) and are taking within 2 weeks before recruitment
3. Severe allergic reaction to other monoclonal antibodies
4. Those who terminated treatment due to related toxicity during anti-PD-1/PD-L1 antibody treatment
5. Prior treatment with bispecific anti-PD-1/CTLA-4 checkpoint blockades or VEGFR inhibitors