A Phase II Study of Orally Administered BEZ235 Monotherapy in Patients With Metastatic or Unresectable Malignant PEComa

Inclusion criteria 1. Histologically confirmed diagnosis of malignant PEComa (included epithelioid AML) of primary disease or of metastatic lesion from archival tissue if it has been obtained within 12 months prior to enrollment in this study. This histological diagnosis includes immunochemistry as follows: * Immunohistochemically positive expression of a melanocytic marker (HMB45, MelanA or microphtalmia transcription factor) AND of a smooth muscle marker (smooth muscle actin, pan-muscle actin, h-caldesmon or calponin) is mandatory on primary or metastatic tumor biopsy. * Note: According to Folpe (2002), criteria for malignancy in non-AML PEComas are: * tumor size of more than 5 cm, * infiltrative growth pattern, * high nuclear grade, * mitotic activity of more than 1/50 high power field (HPF), * necrosis, * vascular invasion * Thus, to be included in the trial, the patient should have tumor presenting with 2 or more criteria for malignancy associated with aggressive clinical behavior. 2. If the primary diagnosis was performed more than 12 months before enrollment, the histology of a primary/metastatic lesion should be reconfirmed with a fresh biopsy. 3. Availability of a representative tumor specimen, either archival or fresh tumor tissue for PI3K pathway analysis. 4. Unresectable/advanced and/or metastatic and documented progressive measurable disease as defined by RECIST 1.1 criteria. Prior to study entry, the progression of the disease should be confirmed by at least 2 sequential CT scans available for documentation (will be collected and hold). 5. Presence of measurable disease according to RECIST 1.1. Note: Lesions in previously irradiated areas can only be considered measurable if they have clearly progressed since the radiotherapy. 6. Treated with 1 or 2 prior lines of treatment Exclusion criteria 1\. Disease exclusions: 1. Lymphangioleiomyomatosis (LAM) exclusively 2. Active uncontrolled or symptomatic CNS metastases Note: A patient with controlled and asymptomatic CNS metastases may participate in this trial. As such, the patient must have completed any prior treatment for CNS metastases \> 28 days (including radiotherapy and/or surgery) prior to start of treatment in this study and should not be receiving chronic corticosteroid therapy for the CNS metastases. 3. Concurrent malignancy or malignancy in the last 3 years prior to start the study treatment (with the exception of adequately treated cervical carcinoma in situ or nonmelanoma skin cancer).