A Study of MHB039A for Advanced Solid Tumor

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