Postoperative Immune Maintenance Therapy for Esophageal Squamous Cell Carcinoma After Radical Resection

Inclusion Criteria:

1. Signed written informed consent prior to the implementation of any trial-relatedprocesses;
2. Male or female, ≥18 years of age or ≤75 years of age;
3. Pathologically confirmed ESCC in the thoracic segment;
4. Received 2-4 cycles of neoadjuvant chemoimmunotherapy and assessed by imaging as CR orPR (clinical staging of cT1b-T2,N+ or cT3-T4a,ANY N) (8th edition UICC/AJCC TNMstaging);
5. Underwent radical surgery, and had negative surgical margins confirmed pathologicallyafter surgery (R0), defined as the absence of squamous carcinoma cells from theproximal, distal, or peripheral resection borders of esophageal carcinoma;
6. Postoperative pathological assessment of non-pCR, and residual tumor in the primarytumor focus or regional lymph nodes.

Exclusion Criteria:

1. Patients with an untreated diagnosis of another malignancy within 5 years prior to thefirst dose (excluding radically treated basal cell carcinoma of the skin, squamousepithelial carcinoma of the skin, and/or carcinoma in situ that has undergone radicalresection);
2. Serious surgical complications after resection of esophageal cancer with reference toClavien-Dindo classification > 3;
3. Individuals with a history of allergy or hypersensitivity to components of the studydrug or severe hypersensitivity to any monoclonal antibody;
4. All toxicities (other than nephropathy, neuropathy, hearing loss, alopecia, andfatigue) attributable to prior antitumor therapy (preoperative induction therapy) musthave recovered to baseline levels or Grade 1 (CTCAE Version 5.0) prior toadministration of study drug;
5. Received systemic therapy with a proprietary medicine with an antitumor indication oran immunomodulatory drug (including thymidine, interferon, interleukin, except forlocal use to control pleural fluid) within 2 weeks prior to the first dose;
6. Women who are pregnant or breastfeeding;
7. Presence of any serious or uncontrollable systemic disease.