Success of 177Lu-DOTATATE therapy in a metastatic pituitary neuroendocrine tumor.

Abstract: Metastatic pituitary neuroendocrine tumors (PitNETs) are rare and often aggressive. Patients should be evaluated for metastatic disease when their biochemical presentation is discordant with pituitary tumor burden or when they present with non-pituitary, site-specific symptoms. Here, we describe the case of a 55-year-old male with an ACTH-secreting PitNET and more than a decade of recurrent transsphenoidal resections, gamma knife irradiation, and therapy with somatostatin analogs and steroidogenesis inhibitors before uncovering metastatic osseous deposits. Only after initiation of peptide receptor radionuclide therapy (PRRT) with 177Lu DOTATATE has he had sustained clinical, biochemical, and structural improvement. There are a limited number of cases of patients with metastatic PitNET who underwent PRRT, but the majority have been favorable with limited adverse events, including hematologic cytopenias, and tumor stability and/or shrinkage. While there are several other off-label, novel therapies used in this population, including non-endocrine targeted therapies or immunotherapy, further studies should evaluate the earlier introduction of PRRT in metastatic PitNET given the good safety profile and overall clinical success. Learning points: Patients with aggressive, recurrent PitNET and discordant biochemical and structural data or site-specific symptoms should be evaluated for evolution of disease, including metastases.There are multiple alternative agents beyond cytotoxic chemotherapy for progressive metastatic PitNETs, including non-endocrine targeted therapies, immunotherapy, and peptide receptor radionuclide therapy (PRRT).PRRT has successfully been used in patients with metastatic PitNET without significant adverse events while stabilizing tumor burden and clinical hormone excess.