Study of galinpepimut-S, a Wilms Tumor-1 (WT1) vaccine, to see if it delays or prevents the mesothelioma from growing back after surgery. WT1 is a protein in cancer cells that regulates gene expression and causes cell growth.

The doctors are testing galinpepimut-S, a Wilms Tumor-1 (WT1) vaccine, to see if it delays or prevents the mesothelioma from growing back after surgery. WT1 is a protein in cancer cells that regulates gene expression and causes cell growth. Mesothelioma tumors generally have high levels of WT1.This study was originally designed to have two treatment groups. One group received non-specific immunotherapy with medications called Montanide and Sargramostim (Granulocyte Macrophage Colony Stimulating Factor, GM-CSF). Enrollment to this group has stopped The other group, which continues receives more specific immunotherapy with galinpepimut-S plus Montanide and GM-CSF. Both Montanide and GM-CSF are commonly given along with vaccines because they have a general effect in boosting the immune response. Some researchers believe that this general increase in the immune system may have some effect in treating cancer. Some studies using GM-CSF with melanoma vaccines have suggested that it could lessen the effects of the vaccine. The addition of the WT1 proteins makes this therapy more directed to mesothelioma. The combination of galinpepimut-S with Montanide and GM-CSF has been tested in a prior trial including 9 patients with advanced mesothelioma. In that trial, the vaccine was safe and caused an immune response.

Inclusion Criteria:

• Pathologic diagnosis of malignant pleural mesothelioma (MPM) confirmed at participating institution.
• Positive immunohistochemical staining for WT-1 (greater than 10% of cells).
• Completion of multimodality therapy. This must include surgical resection by either pleurectomy/decortication or extrapleural pneumonectomy. The surgery should be performed with the intent of complete resection, though patients with an R1 resection will still be eligible. Patients should have also received treatment with chemotherapy and/or radiation. Patients with an R2 resection are also eligible as long as the site of residual disease is treated post-operatively with radiotherapy.
• 4-12 weeks since completion of combined modality therapy.
• Age > or = to 18 years
• Karnofsky performance status > or = to 70%
• Hematologic parameters: Absolute neutrophil count > or = to 1000/mcL, Platelets > or = to 50K/mcL.
• Biochemical parameters: Total bilirubin < or = to 2.0 mg/dl, AST and ALT < or = to 2.5 x upper limits of normal, Creatinine < or = to 2.0 mg/dl.

Exclusion Criteria:

• Pregnant or lactating women.
• Patients with active infection requiring systemic antibiotics, antiviral, or antifungal treatments.
• Patients with a serious unstable medical illness or another active cancer.
• Patients taking systemic corticosteroids.
• Patients with an immunodeficiency syndrome.

Up to 5 years and 11 months, from either start of study or randomization, until primary completion (Nov 2016)