Everolimus-induced somatostatin receptor overexpression in a rectal neuroendocrine tumor patient may promote somatostatin receptor-guided radionuclide therapy (peptide receptor radiotherapy) as an additional treatment option

Abstract

We present a case of Grade II, well-differentiated rectal neuroendocrine tumor in a 39-year-old patient. Following different sequential treatment modalities, the disease progressed both on metabolic (¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography [¹⁸F-FDG PET/CT]) and somatostatin receptor (SSTR)-imaging (⁶⁸Ga-DOTA-Tyr3-octreotate [⁶⁸Ga-DOTATATE] PET/CT), and the patient received three cycles of peptide receptor radiotherapy (PRRT). Two years later, upon new progression due to the appearance of metabolically active, ⁶⁸Ga-DOTATATE PET/CT-negative liver lesions, targeted treatment with everolimus was introduced. Further morphologic and metabolic progression occurred 4 months after everolimus initiation, however, this time liver lesions demonstrated increased SSTR-expression on⁶⁸Ga-DOTATATE PET/CT. Thus, the patient became eligible for a second PRRT course.

Keywords

Everolimus - peptide receptor radiotherapy - somatostatin receptor - up-regulation

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