Evidence Base for the Use of PRRT

Peptide Receptor Radionuclide Therapy Performed Shortly After Administration of Long-Acting Octreotide

ABSTRACT

We present a case of a 68-year-old man with metastatic small bowel neuroendocrine tumor who underwent 4 cycles of peptide receptor radionuclide therapy with 177 Lu-DOTATATE. For his first 3 cycles, therapy was performed approximately 4 weeks after his last dose of octreotide LAR. Because of miscommunication in scheduling, his fourth cycle was performed only 48 hours after his last full dose of octreotide LAR. Despite this, we found that the tumoral uptake was not reduced at all, which may add to the increasing evidence on the nonnecessity of stopping somatostatin analogs before peptide receptor radionuclide therapy.

Improved health-related quality of life during peptide receptor radionuclide therapy in patients with neuroendocrine tumours

Neuroendocrine tumours (NETs) can arise in different locations in the body, and may give rise to hormonal symptoms, which amongst other factors may affect patients' health-related quality of life (HRQoL). Up to four cycles of peptide receptor radionuclide therapy (PRRT) have been shown effective for symptom alleviation and prolonging progression-free survival. The aim of this study was to assess the patient's perspective regarding changes in their HRQoL during PRRT. HRQoL was assessed using the questionnaires for cancer in general, EORTC QLQ-C30, and the gastrointestinal NET-specifically EORTC QLQ-GINET21. Patients with NET (n = 204) rated their HRQoL before PRRT cycles one and four. The medical records of patients were reviewed and their HRQoL was compared to a matched reference population (n = 4910). HRQoL was found to improve during PRRT in aspects of global quality of life; role, social, and emotional functioning, and multiple symptom relief. Potential risk groups for worse HRQoL during PRRT were patients with overweight (BMI >25) who completed four cycles of PRRT and older patients (>65 years old). In conclusion, we found that PRRT improves HRQoL in patients with NETs. The results of this study may be used to improve person-centred care.

Standardized Uptake Values on SPECT/CT: A Promising Alternative Tool for Treatment Evaluation and Prognosis of Metastatic Neuroendocrine Tumours

(1) Background: The aim of our study was to assess the feasibility of 99mTcEDDA/HYNIC-TOC SPECT/CT quantitative analysis in evaluating treatment response and disease progression in patients with NETs. (2) Methods: This prospective monocentric study evaluated 35 SPECT/CT examinations performed on 14 patients with neuroendocrine tumours who underwent a baseline and at least one follow-up 99mTcEDDA/HYNIC-TOC scan as part of their clinical management. The examination protocol included a whole-body scan acquired 2 h after the radiotracer’s administration, with the SPECT/CT performed 4 h post-injection. Images were analyzed by two experienced physicians and patients were classified into response categories based on their changes in SUV values. (3) Results: We evaluated 14 baseline studies and 21 follow-up scans, accounting for 123 lesions. A statistically positive correlation has been found between the SUVmax and SUVpeak values in tumoral lesions (p < 0.05). No correlation has been found between the SUV values and the ki67 proliferation index. Finally, 64.29% patients were classified as SD at the end of the study, with only 14.29% of patients exhibiting PD and 21.43% patients with PR. (4) Conclusions: The quantitative analysis of 99mTcEDDA/HYNIC-TOC SPECT/CT data in patients with neuroendocrine tumours could represent an alternative to 68Ga-DOTA-peptides PET/CT for the monitoring and prognosis of NETs.

Practical Considerations for Implementation of 177Lu-DOTATATE Neuroendocrine Tumor Treatment Programs

The 2018 FDA approval of 177Lu-DOTATATE for the treatment of somatostatin receptor-positive (SSTR) neuroendocrine tumors (NETs) represents a paradigm shifting approach to cancer treatments around the globe. Gastroenteropancreatic (GEP) NETs overexpress the somatostatin subtype receptor 2, which is now exploited for receptor-based imaging and therapy, thus generating significant progress in the diagnosis and treatment of this orphan disease. The recent FDA approval of receptor-based PET radiopharmaceuticals and a new peptide receptor radiopharmaceutical therapy (PRRT), 177Lu-DOTATATE, has dramatically impacted NET patient management. The focus of this paper is to review clinical considerations associated with implementing a 177Lu-DOTATATE program. We review receptor-based NET radiopharmaceuticals, 177Lu-DOTATATE patient selection criteria, administration methods, clinical, regulatory, and radiation safety considerations, technical factors, tissue dosimetry, and reimbursement guidelines.

Overview of the 2022 WHO Classification of Neuroendocrine Neoplasms

In this review, we detail the changes and the relevant features that are applied to neuroendocrine neoplasms (NENs) in the 2022 WHO Classification of Endocrine and Neuroendocrine Tumors. Using a question-and-answer approach, we discuss the consolidation of the nomenclature that distinguishes neuronal paragangliomas from epithelial neoplasms, which are divided into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). The criteria for these distinctions based on differentiation are outlined. NETs are generally (but not always) graded as G1, G2, and G3 based on proliferation, whereas NECs are by definition high grade; the importance of Ki67 as a tool for classification and grading is emphasized. The clinical relevance of proper classification is explained, and the importance of hormonal function is examined, including eutopic and ectopic hormone production. The tools available to pathologists for accurate classification include the conventional biomarkers of neuroendocrine lineage and differentiation, INSM1, synaptophysin, chromogranins, and somatostatin receptors (SSTRs), but also include transcription factors that can identify the site of origin of a metastatic lesion of unknown primary site, as well as hormones, enzymes, and keratins that play a role in functional and structural correlation. The recognition of highly proliferative, well-differentiated NETs has resulted in the need for biomarkers that can distinguish these G3 NETs from NECs, including stains to determine expression of SSTRs and those that can indicate the unique molecular pathogenetic alterations that underlie the distinction, for example, global loss of RB and aberrant p53 in pancreatic NECs compared with loss of ATRX, DAXX, and menin in pancreatic NETs. Other differential diagnoses are discussed with recommendations for biomarkers that can assist in correct classification, including the distinctions between epithelial and non-epithelial NENs that have allowed reclassification of epithelial NETs in the spine, in the duodenum, and in the middle ear; the first two may be composite tumors with neuronal and glial elements, and as this feature is integral to the duodenal lesion, it is now classified as composite gangliocytoma/neuroma and neuroendocrine tumor (CoGNET). The many other aspects of differential diagnosis are detailed with recommendations for biomarkers that can distinguish NENs from non-neuroendocrine lesions that can mimic their morphology. The concepts of mixed neuroendocrine and non-neuroendocrine (MiNEN) and amphicrine tumors are clarified with information about how to approach such lesions in routine practice. Theranostic biomarkers that assist patient management are reviewed. Given the significant proportion of NENs that are associated with germline mutations that predispose to this disease, we explain the role of the pathologist in identifying precursor lesions and applying molecular immunohistochemistry to guide genetic testing.

Perspectives on the current pharmacotherapeutic strategies for management of functional neuroendocrine tumor syndromes

Introduction: In the past, controlling the hormone-excess-state was the main determinant of survival in Functional-Neuroendocrine-Neoplasm-syndromes (F-NENs). This was difficult because the pharmacological-armamentarium available was limited. Recently, new therapeutic strategies have increased but it also generated controversies/uncertainties.Areas covered: The authors briefly review: established/proposed F-NENs; the rationale for treatments; the recommended initial-pharmacotherapeutic-approach to controlling F-NENs hormone-excess-state; the secondary-approaches if the initial approach fails or resistance develops; and the approach to deal with the malignant nature of the NEN. Also discussed are controversies/uncertainties related to new treatments.Expert opinion: Unfortunately, except for patients with insulinomas (>90-95%), gastrinomas (<20-40%), a minority with the other F-panNENs and 0-<1% with Carcinoid-syndrome is curative-surgery possible. Except for insulinomas, gastrinomas, and ACTHomas, long-acting somatostatin-analogs are the initial-pharmacological-treatments for hormone-excess-state. For insulinomas prior to surgery/malignancy, diazoxide is the initial drug-treatment; for gastrinomas, oral PPIs; and for ACTHomas, steroidogenesis inhibitors. There are now several secondary pharmacotherapeutic treatments. Surgery and liver-directed therapies also have a role in selected patients. Particularly promising is the recent results with PRRT for the hormone-excess-state, independent of its anti-growth effect. The sequence to use various agents and the approach to syndrome diagnosis while taking various agents remains unclear/controversial in many cases.