This study is a single arm, non-randomized, open label, multiple doses phase I/II international, multicenter clinical trial to evaluate safety, tolerability, PK/PD, immunogenicity and preliminary efficacy in subjects with advanced malignant neoplasm. The study is consisted of two stages: dose escalation and clinical expansion.

Only Phase I has been submitted to US FDA,and the protocol number is still the same as 6MW3211-2021-CP101.The US title is : A Phase 1, First-in-Human (FIH), Multicenter, Open-Label, Dose Escalation Study to Evaluate the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of 6MW3211 in Patients with Advanced Malignancies .

Six cohorts are included in dose escalation stage, at doses of 0.3~45 mg/kg, respectively. Safety, tolerability, and dose-limiting toxicity (DLT) are assessed during the first 3 weeks (21 days) after initial administration. Then, the intended dosing frequency is every 2 weeks (Q2W), IV.

From the first study drug administration, some dosing cycles will be observed for phase I, initial tumor efficacy assessments will be performed at week 7, after that tumor efficacy assessment will be carry out for every 6 weeks.

Inclusion Criteria:

• 1. Men or women, age ≥18.
• 2.Subjects with advanced malignancy histopathologically and/or cytologically, with at least one evaluable tumor lesion.
• 3.ECOG PS is 0 or 1.
• 4.Survival expectation of at least 3 months.
• 5.Adequate organs and hematopoietic functions
• 6.Voluntarily signing of informed consent

Exclusion Criteria:

• 1.Subjects with brain metastases of clinically active central nervous system (CNS).
• 2.Subjects that require to take anticoagulants and/or aspirin.
• 3.Blood transfusion within 2 weeks prior to the first administration of study treatment.
• 4.Inadequately controlled body cavity effusions.
• 5.Subjects with active, or have a history and possible recurrence of autoimmune diseases .
• 6.Have uncontrolled systemic diseases.
• 7.Subjects who had received anticancer therapy or radiotherapy within 4 weeks or 5 half-lives (whichever is shorter) before enrollment.
• 8.Subjects are known to have previously experienced severe allergic reactions to large molecular protein formulations/monoclonal antibodies.
• 9.Pregnant or lactating women.