Efficacy and Safety of Tislelizumab and Nab-paclitaxel Combined With Low-dose Radiotherapy in Patients With Stage IVb Esophageal Squamous Cell Carcinoma

This study is a single-arm, prospective, open-label clinical study to evaluate the safety and efficacy of tislelizumab combined with chemoradiotherapy in first-line treatment of patients with stage IVb esophageal squamous cell carcinoma.

This study is a single-center, prospective, single-arm, open-label study. It will explore the efficacy and safety of tislelizumab combined with nab-paclitaxel in the first-line treatment of stage IVb esophageal squamous cell carcinoma on the basis of low-dose radiotherapy（40Gy/20f，5次/w）. To explore new treatment modalities and prolong patient survival.

Eligibility Criteria:
Inclusion Criteria:

1. Meet the diagnostic criteria of Esophageal squamous cell carcinoma

   -diagnosed with stage IVb Esophageal squamous cell carcinoma (UICC/AJCC 8th edition TNM staging system) by CT/MRI/PET-CT/ECT, laboratory examination and pathological examination results; specific: any T, any N, M1;
2. No previous anti-tumor treatment; expected survival period of more than half a year; 3.18-75 years old, PS score 0-1;

4. According to RECIST1.1 criteria, there is at least one measurable target lesion, and tumor imaging evaluation is performed within 28 days before the first dose; 5. Major organ function is normal, that is, the following criteria are met: 6. No active autoimmune disease; 7. No active hepatitis; 8. General conditions or medical complications can tolerate radiotherapy, chemotherapy and immunotherapy; 9. No history of malignant tumor, no previous anti-tumor therapy; 10. For premenopausal or surgically sterilized female patients: Consent to abstinence or use of effective contraception during treatment and for at least 7 months after the last dose of study treatment; 11. Understand and sign the informed consent form for this study.

Exclusion Criteria:

1. Previous antitumor therapy or radiation therapy for any malignant tumor;
2. patients receiving standard treatment;
3. concurrently receiving anti-tumor therapy in other clinical trials, including endocrine therapy, bisphosphonate therapy, or immunotherapy;
4. Has undergone major surgical procedures unrelated to colorectal cancer within 4 weeks prior to enrollment, or the patient has not fully recovered from such surgical procedures;
5. Serious heart disease or discomfort, including but not limited to the following:
6. Inability to swallow, bowel obstruction, or other factors that interfere with drug taking and absorption;
7. Known history of allergy to the drug components of this regimen; history of immunodeficiency, including positive HIV test, positive HBV/HCV test, or other acquired or congenital immunodeficiency diseases, or a history of organ transplantation;
8. Pregnant or lactating female patients, female patients of childbearing potential with a positive baseline pregnancy test, or patients of childbearing age who are unwilling to take effective contraceptive measures throughout the trial period and within 7 months after the last study drug;
9. Have serious comorbidities or other comorbidities that would interfere with planned treatment, or any other condition that the investigator considers the patient unsuitable for participation in this study.