HDAC Inhibitor Combination With Chemoimmunotherapy in the Neoadjuvant Treatment of pMMR Locally Advanced Colon Cancer

Inclusion Criteria:

1. Signed written informed consent to voluntarily join this study
2. Patients with colon cancer who are assessed by abdominal contrast-enhanced CT/abdominopelvic MRI as high-risk T3 (tumor destroys muscle wall and extends to pericolonic fat, protruding more than 5 mm into adjacent mesenteric fat) or T4 (tumor penetrates the visceral peritoneal surface or directly invades or adheres to adjacent organs or structures).
3. Adenocarcinoma of the colon confirmed by histopathological examination.
4. At least 18 years old, male or female.
5. Uncomplicated primary tumors (Perforation ； obstruction and bleeding that cannot be relieved by intervention)
6. The lower edge of the tumor is more than 12cm away from the anus.
7. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
8. Adequate bone marrow, liver, renal, and coagulation function as assessed by the laboratory as required by the protocol
9. Have not received any anti-tumor therapy for cancer in the past, including radiotherapy, chemotherapy, surgery, etc.;

Exclusion Criteria:

1. History of previous allergy to monoclonal antibodies, any component of HDACi, and capecitabine;
2. Has received or is receiving any of the following treatments in the past:

   1. Received any treatment against the mechanism of action of tumor immunity, such as immunization, HDACi, etc.
   2. Immunosuppressive drugs, or systemic hormonal drugs within 2 weeks prior to the first use of the study drug to achieve immunosuppressive purposes
   3. Receipt of a live attenuated vaccine within 4 weeks prior to the first use of study drug;
   4. Major surgery or severe trauma within 4 weeks prior to the first use of study drug;
   5. Receipt of systemic non-specific immunomodulatory therapy within 2 weeks prior to the first dose; Have received Chinese herbal medicines or proprietary Chinese medicines with anti-tumor indications within 2 weeks before the first dose.
3. Has any active autoimmune disease or history of autoimmune disease, including but not limited to: interstitial pneumonia, enteritis, hepatitis, hypophysitis, vasculitis, nephritis, hyperthyroidism,
4. dMMR/MSI-H;
5. Presence of cardiac clinical symptoms or diseases that are not well controlled,
6. Severe infection (CTCAE \> grade 2) within 4 weeks prior to the first use of study drug, with active tuberculosis infection found by medical history or CT examination,
7. Presence of active hepatitis B, hepatitis C 8.5 years of diagnosis of other malignant tumors, (adequately treated basal cell carcinoma of the skin or squamous cell skin cancer or carcinoma in situ of the cervix, etc., can be considered for enrollment);

9\. Pregnant or lactating females; 10. As judged by the investigator, there are other factors that may lead to forced termination of the study, such as other serious diseases (including mental illnesses) requiring concomitant treatment, alcoholism, drug abuse, family or social factors, and factors that may affect the safety or compliance of the subject.

11\. Have a history of immunodeficiency, including a positive HIV test, or have other acquired or congenital immunodeficiency disorders, or have a history of organ transplantation or allogeneic bone marrow transplantation;