This is a phase I/II , open-label, multicenter single arm study designed to evaluate the safety, tolerability, pharmacokinetic (PK), and immunogenicity of 6MW3511.

This is a Phase I/II, open-label, dose-escalation trial with consecutive parallel-group expansion in selected solid tumor indications. The study consists of a dose escalation phase to determine the maximum tolerated dose (MTD), or recommended Phase 2 dose (RP2D) for 6MW3511, and a dose expansion phase which will characterize treatment of 6MW3511 at the RP2D.

Inclusion Criteria:

1. In dose-escalation cohorts, histologically or cytologically documented advanced or metastatic solid tumor that is refractory/relapsed to standard therapies, or for which no effective standard therapy is available, or the subject refuses standard therapy.In the dose-expansion cohorts , histologically or cytologically confirmed selected advanced solid tumors (to be determined).
2. Male or female subjects aged over 18 years old (inclusive) and not more than 80 years old (inclusive).
3. Eastern Cooperative Oncology Group (ECOG) Performance Score of 0 or 1.

Exclusion Criteria:

1. History of other malignant tumors within 3 years, except for the tumors that had been cured.
2. Symptomatic or active central nervous system metastasis.
3. Patients with active autoimmune disease.
4. History of allogeneic hematopoietic stem cell transplantation or organ transplantation.
5. Patients previously treated with PD-（L）1/ TGF-β antibody or combined PD-（L）1 with TGF-β antibody.
6. Pregnant or breast feeding.