Perioperative Cadonilimab Combined With Neoadjuvant Chemotherapy in Resectable Esophageal Squamous Cell Carcinoma (ESCC)

Inclusion Criteria: * Be able and willing to provide written informed consent and to comply with all requirements of study participation (including all study procedures). * ≥18 years old and ≤ 75 years (regardless of sex). * Pathologically confirmed esophageal squamous cell carcinoma, assessed as resectable. * Adequate pulmonary function. * Adequate tumor tissue samples. * ECOG performance status of 0-1. * Adequate organ function. * Within 7 days prior to the first dose, women of childbearing potential must have a negative urine or serum pregnancy test and agree to use effective contraception during the study treatment period and for 120 days after the last dose. Exclusion Criteria: * Presence of suspected distant metastatic lesions, or locally advanced unresectable disease. * Histologically confirmed as other pathological types. * Previous surgery precludes the use of gastric substitution for esophageal reconstruction in the current procedure. * History of other malignant tumors within the past 5 years. * Within 4 weeks prior to randomization, presence of conditions such as severe esophagogastric varices, active ulcers, unhealed wounds, gastrointestinal perforation, or intestinal obstruction. * Active or documented history of inflammatory bowel disease. * Clinically symptomatic or recurrent pleural, pericardial, or ascitic fluid requiring drainage. * Uncontrolled concurrent illnesses. * Acute exacerbation of chronic obstructive pulmonary disease within 4 weeks prior to randomization. * History of myocardial infarction, unstable angina, congestive heart failure within 12 months prior to day 1 of study treatment. * History of severe bleeding tendency or coagulation dysfunction. * Arterial thromboembolic events within 6 months prior to randomization. * History or current presence of non-infectious pneumonitis/interstitial lung disease requiring systemic glucocorticoids. * Known psychiatric disorders, drug abuse, or substance addiction. * Pregnant or lactating women. * Prior systemic or local antitumor therapy for locally advanced esophageal squamous cell carcinoma. * Systemic non-specific immunomodulatory therapy within 2 weeks prior to randomization. * Major surgery or severe trauma within 4 weeks prior to randomization. * Known allergy to any component of the investigational drug(s). * Active autoimmune disease requiring systemic treatment within 2 years prior to randomization. * Active hepatitis B infection. * Known active tuberculosis. * Severe infections within 4 weeks prior to randomization. * History of immunodeficiency or positive HIV test. * Known active syphilis infection. * Live vaccination within 4 weeks prior to randomization or planned during the study. * History of allogeneic organ transplantation or hematopoietic stem cell transplantation. * Is currently participating in a study of an investigational agent or using an investigational device.