Inclusion Criteria:

          -  Age >/= 18 years

          -  Karnofsky performance status >/= 70%

          -  Pathologic diagnosis of malignant pleural mesothelioma at MSK

          -  Positive immunohistochemical staining for WT-1 within 60 days of treatment start

          -  Patients must have received at least one prior course of pemetrexed-based chemotherapy

          -  Patients of childbearing potential must have a negative serum pregnancy test within 24
             hours of receiving the first treatment on the study (if female) and must be practicing
             an effective form of birth control for the entire duration of treatment (both females
             and males)

          -  Has received and progressed or are refractory to pemetrexed based chemotherapy

          -  Measurable or evaluable disease

          -  Biochemical parameters: Total bilirubin < 1.5 mg/dl, AST and ALT < 3.0 x upper limits
             of normal, Creatinine < 1.5 x upper limits of normal

        Exclusion Criteria:

          -  Pregnant or lactating women

          -  Prior receipt of checkpoint inhibition

          -  Patients with known active hepatitis B or known active hepatitis C virus

          -  Patients with a serious unstable medical illness or another active cancer

          -  Patients with known history of testing positive for human immunodeficiency virus (HIV)
             or known acquired immunodeficiency syndrome (AIDS)

          -  Autoimmune disease requiring treatment with systemic steroids in the past 2 years

          -  Current use of systemic corticosteroids at doses greater than prednisone 10 mg daily
             or the equivalent

          -  Patients with active pneumonitis

          -  Hematologic parameters: Absolute neutrophil count >/= 1000/mcL

          -  Platelet count <100,000