Definitive chemoradiotherapy (CRT) is the standard treatment option for unresectable esophageal cancer (EC). However, as high as more than 40% of EC patients experienced locoregional recurrence after concurrent CRT. Immunotherapy targeting the PD-1/PD-L1 checkpoints has demonstrated promising activity in advanced EC. The aim of this study was to evaluate the efficacy and safety of the combination of toripalimab (an anti-PD-1 antibody) combined with definitive CRT in locally advanced esophageal squamous cell carcinoma (ESCC).

Inclusion Criteria:

1. Histologically confirmed squamous cell carcinoma of the esophagus;
2. Absence of hematogenous metastasis disease, confirmed by endoscopic ultrasound (EUS) and PET-CT scan (according to UICC TNM version 8);
3. Not suitable for surgery (either for medical reasons or patient's choice);
4. Age at diagnosis 18 to 70 years;
5. No prior cancer therapy;
6. Estimated life expectancy >6 months;
7. Eastern Cooperative Oncology Group performance status ≤ 2
8. No history of concomitant or previous malignancy;
9. The function of important organs meets the following requirements: a. white blood cell count (WBC) ≥ 4.0×109/L, absolute neutrophil count (ANC) ≥ 1.5×109/L; b. platelets ≥ 100×109/L; c. hemoglobin ≥ 9g/dL; d. serum albumin ≥ 2.8g/dL; e. total bilirubin ≤ 1.5×ULN, ALT, AST and/or AKP ≤ 2.5×ULN; f. serum creatinine ≤ 1.5×ULN or creatinine clearance rate >60 mL/min;
10. Ability to understand the study and sign informed consent.

Exclusion Criteria:

1. Patients who have been treated previously with anti-tumor therapy (including chemotherapy, radiotherapy, surgery, immunotherapy, etc.);
2. Patients with hematogenous metastasis disease at diagnosis;
3. Known or suspected allergy or hypersensitivity to monoclonal antibodies, any ingredients of Toripalimab, and the chemotherapeutic drugs paclitaxel or cisplatin;
4. Patients who have a preexisting or coexisting bleeding disorder;
5. Female patients who are pregnant or lactating;
6. Inability to provide informed consent due to psychological, familial, social and other factors;
7. Presence of CTC grade ≥ 3 peripheral neuropathy;
8. A history of malignancies other than esophageal cancer before enrollment, excluding non-melanoma skin cancer, in situ cervical cancer, or cured early prostate cancer
9. A history of diabetes for more than 10 years and poorly controlled blood glucose levels;
10. Patients who cannot tolerate chemoradiotherapy due to severe cardiac, lung, liver or kidney dysfunction, or hematopoietic disease or cachexia.
11. Active autoimmune diseases, a history of autoimmune diseases (including but not limited to these diseases or syndromes, such as colitis, hepatitis, hyperthyroidism), a history of immunodeficiency (including a positive HIV test result), or other acquired or congenital immunodeficiency diseases, a history of organ transplantation or allogeneic bone marrow transplantation;
12. A history of interstitial lung disease or non-infectious pneumonia;
13. A history of active pulmonary tuberculosis infection within 1 year or a history of active pulmonary tuberculosis infection more than 1 year ago but without formal anti-tuberculosis treatment;
14. Presence of active hepatitis B (HBV DNA ≥ 2000 IU/mL or 104 copies/mL), hepatitis C hepatitis C antibody, and HCV-RNA levels higher than the lower limit of the assay).