Neoadjuvant Therapy for Locally Advanced Rectal Cancer

Inclusion Criteria:

-Patient's age: 18 years old - 80 years old -

• Rectal cancer patients diagnosed with adenocarcinoma by pathological examination ofprimary biopsy

• Patients with no prior treatment, preoperative clinical stage: cT3-4N+M0 rectalcancer patients (AJCC 8th);

• Patients who agree to undergo radical surgical treatment and have nocontraindications to surgery as judged by the surgeon;

• No other multiple primary cancers;

• At least 1 measurable or evaluable lesion according to the efficacy evaluationcriteria for solid tumors version 1.1 (RECIST v1.1);

• Expected survival time≥ 3 months;

• A score of 0-1 based on the United States Eastern Cooperative Oncology GroupPerformance Status Score (ECOG PS score);

• The investigator plans to give PD-1 monoclonal antibody combined with chemotherapytreatment regimen after evaluation, and signs informed consent.

Exclusion Criteria:

• Active, known or suspected autoimmune disease;

• Known history of primary immunodeficiency;

• Known history of allogeneic organ transplantation and allogeneic hematopoietic stemcell transplantation;

• Pregnant or lactating female patients;

• Patients with intestinal obstruction, intestinal perforation, intestinal bleeding,etc., requiring emergency surgery;

• Uncontrolled intercurrent illness including but not limited to:

• People living with HIV (HIV antibody positive)

• Severe infections that are active or poorly clinically controlled

• Patients with active hepatitis

• Evidence of severe or uncontrolled systemic disease (e.g., severe psychiatric,neurological, epilepsy or dementia, unstable or incompensable respiratory,cardiovascular, hepatic or renal disease, uncontrolled hypertension [i.e., greaterthan or equal to CTCAE grade 2 hypertension despite medication]).

• Patients with active bleeding or new thrombotic disease, taking therapeutic dose ofanticoagulant drugs or bleeding tendency, abnormal coagulation function (INR>1.5×ULN, APTT>1.5×ULN);

• Those who are currently undergoing clinical trials of other drugs;

• Other patients who are considered by the investigator to be unsuitable forinclusion.