• Males or females, aged 18 years or older.

• Patients with histologically confirmed colorectal cancer that has been determined to be unresectable or metastatic.

• Colorectal cancer subjects who are unsuitable or unable to tolerate standard systemic therapy, or who have received standard systemic therapy but have disease progression based on RECIST (version 1.1) criteria, including chemotherapy based on fluorouracil, oxaliplatin, or irinotecan, and targeted therapies with anti-VEGF/EGFR monoclonal antibodies.

• Patients with confirmed deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H) in tumor tissue, who have been treated with immune checkpoint inhibitors (anti-PD-1 or anti-PD-L1 antibodies) and are assessed with disease progression.

• According to the RECIST (version 1.1) criteria, there are measurable target lesions suitable for repeated measurements for assessment.

• Life expectancy of 12 weeks or more.

• Subjects must have an Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) of 0 to 2.

• Males with fertility and females of childbearing potential are willing to use a highly effective method of contraception for the entire study period and for 6 months after study drug discontinuation. Females of childbearing age, including premenopausal females and within 2 years after menopause, must have a negative serum pregnancy test result within 7 days prior to the first dose of study treatment.

• Subjects who had a voluntary agreement to provide written informed consent and the willingness and ability to comply with all aspects of the protocol.