This study is a phase II, single arm study with main purpose to evaluate the safety, tolerability and efficacy of Tislelizumab as adjuvant therapy for patients with high-risk stage Ⅱ and stage Ⅲ colon cancer and deficient mismatch repair or microsatellite instability.~Tumour MMR status will be routinely tested locally as per NICE guidelines (either in the pre-operative biopsy or resection specimen). Subjects whose tumours are dMMR can sign the main study consent and undergo the study screening procedures.All eligible patients receive received 200 mg Tislelizumab intravenously every 3 weeks until disease progression, unacceptable adverse events (AEs) or withdrawal of consent. The maximum duration of the trial intervention period was 1 year.
10%-15% of early-stage colon cancers harbour either deficient mismatch repair (dMMR), microsatellite instability high (MSI-H) is characterised by high tumour mutational burden and increased lymphocytic infiltrate. Metastatic dMMR colon cancers are highly sensitive to immune checkpoint inhibition.The MSI phenotype is associated with a better prognosis than MSS in stage II and III CRCs. However, there are conflicting data about the benefit of adjuvant chemotherapy in this group of patients.~We are conducting a single arm study phase II trial to determine if the anti-PD-1 antibody Tislelizumab improves disease-free survival (DFS) in patients with high risk stage II and stage III dMMR/MSI-H colon cancer.