This multicenter, prospective Phase II study investigates a response-adapted organ-preservation strategy in patients with resectable esophageal squamous cell carcinoma (ESCC). Participants will receive two cycles of induction chemoimmunotherapy with sugemalimab, nab-paclitaxel, and cisplatin. Patients who achieve a major clinical response will receive definitive radiotherapy plus sugemalimab followed by maintenance sugemalimab, while non-major responders will undergo surgery-based treatment strategies. The study aims to evaluate the efficacy and safety of this tailored treatment approach, with the primary endpoint being 2-year progression-free survival. Secondary and exploratory objectives include survival outcomes, quality of life, nutritional status.

Inclusion Criteria:

Age 18-75 years. Histologically confirmed, previously untreated resectable esophageal squamous cell carcinoma (ESCC).

Clinical stage IB-III according to AJCC 8th edition. ECOG performance status 0-1. Adequate hematologic, hepatic, and renal function. Ability to provide written informed consent.

Exclusion Criteria:

Prior systemic therapy, radiotherapy, surgery, or immunotherapy for ESCC. Distant metastases or suspicious cervical lymph node metastases. Prior treatment with PD-1 or PD-L1 inhibitors. Active autoimmune disease requiring systemic treatment. Uncontrolled infection, including active hepatitis or HIV infection. Significant cardiovascular, pulmonary, or other serious medical conditions that may interfere with study participation.