Advances in Endocrine Tumor PET Imaging Targeting CXCR4 and GLP-1

Molecular imaging has experienced significant advances in the areas of imaging probes and technology, enabling the detection of tumors at earlier stages and more accurately identifying extent of disease. To better characterize lesions, nuclear medicine modalities utilize molecular imaging agents targeting specific pathways and cell surface molecules to improve both sensitivity and specificity. In the field of endocrinology, tumors encompass a wide spectrum of aggressiveness ranging from indolent, well differentiated tumors to highly aggressive cancers. Thus, in recent years, new molecular imaging biomarkers have been developed for noninvasively assessing different types of hormone-producing tumors. For instance, ⁶⁸Ga-PentixaFor is a novel PET imaging agent targeting the C-X-C chemokine receptor type 4 (CXCR4) with proven utility in various malignancies, and has also shown multifunctionality in detecting endocrine pathologies, such as primary aldosteronism, adrenocorticotropic hormone (ACTH)-producing pituitary adenomas and ACTH-independent cortisol-producing adrenal adenomas. Another novel receptor-targeted radiotracer using the glucagon-like peptide-1 receptor (GLP-1R) analog, Exendin-4 has recently developed to preoperatively localize insulinomas, arising from pancreatic beta cells. This review presents an overview of new developments and potential clinical implementation of CXCR4- and Exendin- based radiotracers for imaging applications in endocrinology.