RecruitingPhase 1Drug trialImproving Peptide Receptor Radionuclide Therapy With PARP InhibitorsThis is a phase 1 dose-escalation study to determine the maximum tolerated dose of the PARP inhibitor olaparib in combination with PRRT in patients with a well-differentiated advanced gastroenteropancreatic NET (GEP NET), progressive after PRRT. As secondary objectives, efficacy, pharmacokinetics and biomarker response will be investigated.