A multicenter, two stage, phase II study, evaluating the efficacy of oral BEZ235 plus best supportive care (BSC) versus placebo plus BSC in the treatment of patients with advanced pancreatic neuroendocrine tumors (pNET) after failure of mTOR inhibitor therapy

1. Patient must have advanced, histologically confirmed low or intermediate grade pancreatic pNET according to the WHO 2010 classification and show radiological evidence of disease progression since last treatment.
NOTE: Tissue (archival or fresh) must be provided if available in order to identify molecular profiles relevant to PI3K pathway signaling.
2. Patients* disease is refractory to treatment with mTOR inhibitor. Patients must not have taken another treatment between mTOR inhibitor and BEZ235.
NOTE: Refractory is defined as progression while on treatment or within 3 months of treatment discontinuation.
3. Measurable disease per RECIST Version 1.1 using Computed Tomography (CT) or Magnetic Resonance Imaging (MRI).
4. Prior or concurrent therapy with SSA is permitted; however, for concurrent therapy with SSA while on study, patients must be on a stable dose at least 2 months prior to study start and must continue on the stable dose while receiving study treatment.
5. Adequate bone marrow function or organ function as shown by:
* Absolute Neutrophil Count (ANC) * 1.5 x 109/L,
* Platelets * 100 x 109/L
* Hemoglobin > 9 g/dL
* INR < 2.0,
* Serum creatinine * 1.5 x ULN,
* Total serum bilirubin * 1.5 x ULN
* ALT and AST * 3 x ULN (or * 5x ULN in patients with liver metastases),
* Fasting plasma glucose (FPG) * 140 mg/dL or * 7.8 mmol/L,
* HbA1c * 8%.
6. WHO PS * 1.
7. Adult male or female patients * 18 years of age.
8. Written informed consent obtained before any trial related activities and according to local guidelines.

1. Patient has received previous treatment with any PI3K inhibitor or AKT inhibitor for the treatment of pNET.
2. Patient has discontinued prior mTOR inhibitor therapy due to toxicity
3. Patient has poorly differentiated neuroendocrine carcinoma, high-grade neuroendocrine carcinoma, adenocarcinoid, goblet cell carcinoid and small cell carcinoma.
4. Patient has received cytotoxic chemotherapy, targeted therapy, immunotherapy, radiotherapy, or major surgery within 4 weeks prior to enrolment in the study.
5. Patient has been treated with hepatic artery embolization within the last 6 months or cryoablation/ radiofrequency ablation of hepatic metastasis within 2 months of enrollment.
6. Patients with more than 3 prior systemic treatment regimens.
7. Patient is being treated at start of study treatment with any of the following drugs:
* Drugs known to be moderate and strong inhibitors or inducers of isoenzyme CYP3A4
* Drugs with a known risk to induce Torsades de Pointes
* Warfarin and coumarin analogues
8. Patient is consuming Seville oranges, grapefruit, pummelos and exotic citrus fruits (during the last 7 days prior to start of treatment.
9. Patient who has any severe and/or uncontrolled medical conditions, for example:
* active or uncontrolled severe infection,
* cirrhosis, chronic active hepatitis or chronic persistent hepatitis,
* severely impaired lung function inadequately controlled hypertension (i.e., SBP>180 mmHg or DBP>100mmHg),
* active bleeding diathesis.
10. Patient has any of the following cardiac abnormalities:
* symptomatic congestive heart failure, myocardial infarction * 6 months prior to enrolment,
* unstable angina pectoris,
* serious uncontrolled cardiac arrhythmia,
* symptomatic pericarditis,
* history of documented congestive heart failure; documented cardiomyopathy,
* abnormal Left Ventricular Ejection Fraction (LVEF) as determined by Multiple Gated acquisition (MUGA) scan or echocardiogram (ECHO),
* QTcF > 480 msec on the screening ECG
* currently receiving treatment with medication that has a known risk to prolong the QT interval or inducing Torsades de Pointes,
11. Patient has impairment of GI function or GI disease that may significantly alter the absorption of study drug (e.g., ulcerative diseases, uncontrolled nausea, vomiting, diarrhea, malabsorption syndrome, or small bowel resection).
12. Patient is receiving chronic high dose treatment with corticosteroids or another immunosuppressive agent that would cause the patient to be immunocompromised.
13. Patient is immunocompromised, including known seropositivity for HIV.
14. Patient has other prior or concurrent malignancy
15. Patient has a history of non-compliance to medical regimen or is considered potentially unreliable or is unable to grant consent.
16. Patient is a pregnant or nursing (lactating) woman,
17. Patient who does not apply highly effective contraception during the study and through the duration, as defined below, after the final dose of study treatment.