Inclusion Criteria:
1. Volunteered to participate, cooperated with follow-up visits, documented informed consent;
2. Aged 18 -75 years, both male and female;
3. Histologically confirmed cT1N2-3M0 or cT2-4bN0-3M0 or cT1-4bN0-3M1( supraclavicular lymph node metastasis) locally advanced ESCC (8th AJCC); clinically staged as II-IVb inoperable locally advanced ESCC (including non-resectable, or with contraindications to or refusal of surgery);
4. Measurable and/or unmeasurable lesions as defined by the criteria for evaluating the efficacy of solid tumors (RECIST1.1) and the Japanese Classification of Esophageal Cancer (12th Edition: Part II);
5. Haven't received any previous systemic anti-tumor therapy (including but not limited to systemic chemotherapy, radiotherapy, molecularly targeted drug therapy, immunotherapy, biologic therapy, topical therapy and other investigational therapeutic agents);
6. ECOG performance status 0 or 1;
7. Provide fresh or archived tumour tissue samples within 6 months (fresh samples preferred) for biomarker analysis (e.g.PD-L1). Sample types are formalin-fixed, paraffin-embedded \[FFPE\] tumour tissue blocks or at least 5 unstained, 3-5 μm thick FFPE tumour tissue sections;
8. Expected survival ≥ 3 months;
9. Adequate hematologic function, defined as ANC ≥1500/μl, platelet count ≥100,000/μl and hemoglobin count ≥9.0 g/dl or ≥5.6 mmol/l; Adequate renal function, defined as creatinine ≤1.5× ULN or measured or calculated creatinine clearance ≥60 mL/min for those with creatinine levels \>1.5× ULN (Calculated from the Cockcroft-Gault formula); Adequate hepatic function, defined as total bilirubin ≤1.5× ULN and ALT/AST/AKP levels ≤2.5× ULN and albumin ≥2.8 g/dl; Adequate coagulation function, defined as INR ≤1.5× ULN and APTT≤1.5× ULN unless the patient is receiving anticoagulant therapy as long as INR is within the therapeutic range;
10. Women of childbearing potential with a negative urine pregnancy test within 3 days before the first administration of the investigational drugs.
Exclusion Criteria:
1. Surgery for esophageal cancer;
2. Esophageal fistulae due to infiltration of the primary tumour;
3. Risk of gastrointestinal bleeding, oesophageal fistula or oesophageal perforation
4. Poor nutritional status, weight loss of ≥10% in the previous 2 months, with no significant improvement after nutritional intervention;
5. Major surgery or severe trauma within 4 weeks prior to first use of study drug;
6. Uncontrollable pleural effusion, pericardial effusion, or ascites that requires repeated drainage;
7. Received or receiving any of the following treatments in the past:
1. Anti-PD-1 or anti-PD-L1 antibody therapy, chemotherapy, radiotherapy or targeted therapy;
2. Participation in a study of an investigational agent or device within 4 weeks before the first dose of study treatment;
3. Systemic treatment with corticosteroids (\>10 mg prednisone equivalent dose per day) or other immunosuppressive agents is required for 2 weeks before the first dose of study treatment(except for the use of corticosteroids for local inflammation of the oesophagus and for the prevention of allergy and nausea and vomiting). Other special circumstances need to be communicated to the sponsor.Inhaled or topical steroids and adrenocorticotropic hormone replacement at doses \>10mg/day prednisone efficacy dose are permitted if the patient does not have active autoimmune disease;
4. Received an anti-tumour vaccine or received a live vaccine within 4 weeks before the first dose of study treatment;
8. Any active autoimmune disease or history of autoimmune disease (e.g., interstitial pneumonitis, uveitis, enteritis, hepatitis, pituitary gland inflammation, vasculitis, myocarditis, nephritis, hyperthyroidism, hypothyroidism);Except for patients with vitiligo or those who had asthma or allergies in childhood but did not need any intervention as adults; patients with autoimmune-mediated hypothyroidism treated with stable doses of thyroid replacement hormone and type I diabetes mellitus treated with stable doses of insulin may be included;
9. Diagnosis of immunodeficiency, including positive HIV test,other acquired/congenital immunodeficiency diseases, organ transplantation and allogeneic bone marrow transplantation;
10. Diagnosis of uncontrolled cardiac clinical symptoms or disease such as a.NYHA II or above heart failure b.unstable angina c.myocardial infarction within 1 year d.clinically significant supraventricular or ventricular arrhythmias requiring clinical intervention;
11. Severe infections (CTCAE \> Grade 2), such as severe pneumonia requiring hospitalisation, bacteraemia, infectious co-morbidities, etc., within 4 weeks before the first use of study treatment; Baseline chest imaging suggestive of active lung inflammation, signs and symptoms of infection requiring oral or intravenous antibiotic treatment within 2 weeks before the first use of study treatment, except for prophylactic antibiotic use;
12. History of interstitial lung disease or non-infectious pneumonia, or pulmonary insufficiency ≥ grade 3 as confirmed by pulmonary function tests;
13. Active tuberculosis infection detected by history or CT examination, or history of active tuberculosis infection within 1 year before enrollment or more than 1 year previously without regular treatment;
14. Presence of active hepatitis B (HBV DNA ≥ 2000 IU/mL or 104 copies/mL), hepatitis C (hepatitis C antibody positive and HCV-RNA above the lower limit of detection);
15. Presence of abnormal sodium, potassium, and calcium laboratory test values greater than Grade 1 within 2 weeks prior to randomisation that do not improve with treatment;
16. Known hypersensitivity to large protein preparations, or to any of the components of nab-paclitaxel or carboplatin or to any of the components used within their preparations;
17. Any other malignant tumor was diagnosed before the first use of the study drug, except for malignant tumors with a low risk of metastasis and death (5-year survival rate \> 90%), such as well-treated basal cell or squamous cell skin cancer or cervical carcinoma in situ;
18. Pregnant or lactating patients;
19. After the researchers' judgment, the subjects have other factors that may force them to terminate the study halfway, such as suffering from other serious diseases (including mental disorders) that require combined treatment, having other serious diseases recently (such as myocardial infarction, cerebrovascular accident) that are considered to have a high risk of recurrence, severely abnormal laboratory test values, family or social factors. Situations that may affect the safety of the subjects or the collection of experimental data.
