PM8002 (BNT327) is a bispecific antibody targeting PD-L1 and VEGF. This is a phase II trial to evaluate the efficacy and safety of PM8002 in combination with chemotherapy in first line MSS or MSI-L/pMMR metastatic colorectal cancer.

A multicenter, randomized, open-label study design is used, with a planned enrollment of 40 participants, 30 in the PM8002 (BNT327)+ chemotherapy regimen 1 group and 10 in the PM8002 (BNT327)+ chemotherapy regimen 2 group. The investigators make the decision on which chemotherapy regimen to be used in the participants. After combined chemotherapy regimen is confirmed, participants will be randomized to one of two dose levels of PM8002(BNT327) plus chemotherapy.

Key Inclusion Criteria:

1. Signed informed consent form before any trial-related processes.
2. Age ≥ 18 years male or female.
3. Histologically or cytologically confirmed metastatic colorectal cancer (stage IV, UICC/AJCC staging system) that is not suitable for or cannot be radically resected surgically.
4. Participants must not have dMMR or MSI-H.
5. No prior systemic anti-tumor therapy for metastatic colorectal cancer.
6. have adequate organ function.
7. The investigator confirms at least one measurable lesion according to RECIST v1.1. A measurable lesion located in the field of previous radiation therapy or after local treatment may be selected as a target lesion if progression is confirmed.
8. The Eastern Cancer Cooperative Group (ECOG) performance score of 0 or 1.

Key Exclusion Criteria:

1. Received the following treatments or medications prior to starting study treatment:

   1. Received palliative local therapy, non-specific immunomodulatory therapy, or chineses herbal therapy with an anti-tumor indication within 14 days prior to study treatment.
   2. Treatment with systemic glucocorticoids (prednisone >10 mg/day or equivalent dose of other glucocorticoids) or other immunosuppressive agents within 14 days prior to initiation of study treatment. Note: treatment with local, intraocular, intra-articular, intranasal, and inhaled glucocorticosteroids and short-term prophylactic use of glucocorticoids (e.g., to prevent allergy to contrast agent) are allowed.

2. Have a major coagulation disorder or other evidence of significant bleeding risk.

3. Adverse effects of prior antitumor therapy have not returned to a CTCAE 5.0 grade rating of ≤ grade 1

4. Have a serious non-healing wound, ulcer, or bone fracture.

5. History of abdominal fistula, gastrointestinal perforation, or abdominal abscess, history of gastrointestinal obstruction, or clinical signs of gastrointestinal obstruction within 6 months prior to initiation of study treatment.

6. Severe uncontrollable intra-abdominal inflammation that requires clinical intervention, in the judgment of the investigator.

7. Have uncontrolled hypertension or poorly controlled diabetic conditions prior to study treatment.