Phase I/II open label, multicenter study to evaluate the efficacy and safety of MHB039A in advanced malignant tumors.

This first-in-human, dose escalation and dose expansion study is to evaluate the safety, tolerability, pharmacokinetics (PK), immunogenicity, pharmacodynamics (PD) and anti-tumor activity of MHB039A in patients with advanced solid tumor. The Phase I stage （dose escalation）is to determine the maximum tolerated dose (MTD). The phase II stage （dose expansion）is to determine the recommended Phase 2 dose (RP2D) according to safety and efficacy in specific tumor types.

Inclusion Criteria:

• 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.
• Written and signed informed consent
• Aged 18 years or older
• Eastern Cooperative Oncology Group (ECOG) Performance Score of 0 or 1
• Life expectancy >=3 months

Exclusion Criteria:

• Prior malignancy active within the previous 5 years except for the tumor for which a subject is enrolled in the study, and locally curable cancers that have been apparently cured, (e.g. basal cell skin cancer, or carcinoma in situ of the cervix or others)
• Receiving any chemotherapy within 3 weeks prior to the first dose；or other systemic anticancer therapy within 4 weeks prior to the first dose
• Receiving prior anti-PD-1, anti-PD-L1, anti-CTLA(cytotoxic T-lymphocyte-associated protein)-4 or any other immunotherapy or immune-oncology (IO) agent within 28 days of first dose with MHB039A or experienced a toxicity that led to permanent discontinuation of prior immunotherapy
• Unresolved toxicities from prior anticancer therapy