PhII Study of Toripalimab Followed by Definitive CRT & Adjuvant Toripalimab in Locally Advanced ESCC

Inclusion Criteria: 1. Signed and dated written informed consent. 2. Age ≥ 18 years the day of signing informed consent. 3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 1. 4. Previously untreated, resectable, histologically confirmed stage II-IVA esophageal squamous cell carcinoma according to the 8th TNM staging system of the American Joint Committee on Cancer. 5. Has provided archival or newly obtained core or excisional biopsy tissue (fine needle aspirate \[FNA\] is not adequate) of a tumor lesion for local standard of care biomarker analysis. Repeat samples may be required if adequate tissue is not provided. Note: Formalin-fixed, paraffin embedded tissue blocks are preferred to slides. 6. Adequate organ and bone marrow function resulted ≤ 28 days prior to first dose of protocol-indicated treatment: * Absolute neutrophil count (ANC) ≥ 1500/µL. * Platelets ≥ 100,000/µL. * Hemoglobin ≥ 7.0 g/dL * Estimated glomerular filtration rate (eGFR) ≥ 60 mL/min (as calculated by the Cockcroft-Gault Formula or calculated/measured by an alternative established institutional standard consistently applied across participants at the site) or serum creatinine ≤ 1.5x upper limit of normal (ULN) * Total bilirubin ≤ 1.5 times institutional ULN * AST (SGOT) and ALT (SGPT) ≤ 2.5 times institutional ULN. * Serum albumin ≥ 2.8 g/dL Exclusion Criteria: 1. Locally advanced and incurable or metastatic disease is deemed incurable. 2. History of another malignancy within 3 years prior to screening, except for non-melanoma skin carcinoma, low-grade localized prostate cancer, superficial bladder cancer, ductal carcinoma in situ (CIS) of the breast, CIS of the cervix, or stage I uterine cancer. 3. Multiple primary esophageal cancers. 4. Previous radiotherapy of the thorax. 5. Previous immune checkpoint inhibitor therapy (including agents targeting PD-1, PD-L1/PD-L2, CTLA-4, LAG-3, TIGIT). 6. Active autoimmune disease, solid organ transplant recipient, or prednisone dose (or a steroid equivalent) of more than 10mg daily. 7. Previous non-infectious pneumonitis or interstitial lung disease. 8. Any severe comorbidity (e.g. uncontrolled diabetes or decompensated heart failure) which in the determination of the treating physician would preclude the patient from receiving this experimental treatment regimen. 9. Contraindication to ICI or suspected allergy/hypersensitivity to monoclonal antibodies or any ingredients of toripalimab. 10. Known allergy/hypersensitivity to carboplatin or paclitaxel. 11. Inability to provide informed consent due to psychological, familial, social, or other factors. 12. Presence of CTCAEv6 grade ≥ 2 neuropathy. 13. Pregnant or breastfeeding.