Inclusion Criteria:

          -  Able to understand and willing to sign the ICF.

          -  Male or female subject ≥ 18 years.

          -  Histologically/cytologically confirmed, locally advanced unresectable or metastatic
             solid tumors that are refractory to standard therapy, or for which no standard therapy
             exists.

          -  Subject has measurable disease per RECIST v1.1.

          -  ECOG Performance Status 0 to 1

          -  Subjects with life expectancy of ≥ 3 month

          -  No herbal/alternative medications prior to the first dose

          -  Must have adequate hematological, hepatic and renal function as defined in the
             protocol.

          -  Prior anti-tumor therapies of different kinds must have stopped before the first dose
             as defined by protocol

          -  Effective contraception for both male and female subjects if the risk of conception
             exists

        Exclusion Criteria:

          -  Pregnant or nursing females.

          -  Any remaining AEs > grade 1 from prior anti-tumor treatment as per CTCAE v4. 03, with
             exception of the residual hair loss;

          -  Received a biologic G-CSF, GM-CSF or erythropoietin within 14 days prior to the first
             dose of study drug;

          -  Subjects who had prior treatment with an anti-PD-L1 product

          -  History of documented autoimmune disease except for autoimmune hypothyroidism and
             well-controlled Type 1 diabetes mellitus.

          -  W/o autoimmune condition requiring systemic treatment with immunosuppressive
             medications within 14 days before the planned first dose of study drug.

          -  Primacy central nervous system (CNS) malignancy or symptomatic CNS metastases are not
             allowed, with exceptions defined in protocol.

          -  Major surgery within the 28-days from the screening

          -  Subjects with idiopathic pulmonary fibrosis or unresolved active or chronic
             inflammatory pulmonary disease are excluded.

          -  History of human immunodeficiency virus (HIV) infection, active hepatitis B or C. HBV
             carriers

          -  History of primary immunodeficiency, stem cell or organ transplant, or previous
             clinical diagnosis of tuberculosis disease.

          -  Clinically significant acute infections 4 weeks and any infection 2 weeks prior to the
             first dose administration.

          -  Known allergies, hypersensitivity, or intolerance to protein-based therapies or with a
             history of any significant drug allergy

          -  Subjects who experienced immunotherapy-related adverse events (irAE) grade ≥ 3, or who
             had to discontinue prior anti-PD-1 treatment due to irAEs of any grade.

          -  Severe or uncontrolled cardiac disease requiring treatment as defined in protocol

          -  Any other serious underlying medical, psychiatric, psychological, familial or
             geographical condition that, in the judgment of the investigator, might impair the
             subject's benefit from the trial treatment

          -  Known history of hypersensitivity to any components of the MSB2311 product.