This study enrolled participants with Stage II or III resectable colorectal cancer (CRC). Participants with unknown microsatellite instability (MSI) or mismatch repair (MMR) status provided blood and tumor tissue samples during a prescreening period (within 56 days before the first dose) for central laboratory confirmation of MSI status. Participants with known MSI-high (MSI-H) or deficient MMR (dMMR) status by local laboratory also underwent central confirmation when tumor samples were available. Eligible participants received tislelizumab 200 mg by intravenous infusion once every 3 weeks for 3 cycles as neoadjuvant therapy. After completion of neoadjuvant treatment, participants underwent complete surgical removal (R0 resection) of their tumor, and surgical specimens were assessed for pathological response, including major pathological response (MPR) and pathological complete response (pCR). Post-surgery, participants continued adjuvant therapy and follow-up as determined by their investigator.
