CXCR4: From Signaling to Clinical Applications in Neuroendocrine Neoplasms.

There are several well-described molecular mechanisms that influence cell growth and are related to the development of cancer. Chemokines constitute a fundamental element that is not only involved in local growth but also affects angiogenesis, tumor spread, and metastatic disease. Among them, the C-X-C motif chemokine ligand 12 (CXCL12) and its specific receptor the chemokine C-X-C motif receptor 4 (CXCR4) have been widely studied. The overexpression in cell membranes of CXCR4 has been shown to be associated with the development of different kinds of histological malignancies, such as adenocarcinomas, epidermoid carcinomas, mesenchymal tumors, or neuroendocrine neoplasms (NENs). The molecular synapsis between CXCL12 and CXCR4 leads to the interaction of G proteins and the activation of different intracellular signaling pathways in both gastroenteropancreatic (GEP) and bronchopulmonary (BP) NENs, conferring greater capacity for locoregional aggressiveness, the epithelial-mesenchymal transition (EMT), and the appearance of metastases. Therefore, it has been hypothesized as to how to design tools that target this receptor. The aim of this review is to focus on current knowledge of the relationship between CXCR4 and NENs, with a special emphasis on diagnostic and therapeutic molecular targets.

Genomic and immune landscape Of metastatic pheochromocytoma and paraganglioma.

The mechanisms triggering metastasis in pheochromocytoma/paraganglioma are unknown, hindering therapeutic options for patients with metastatic tumors (mPPGL). Herein we show by genomic profiling of a large cohort of mPPGLs that high mutational load, microsatellite instability and somatic copy-number alteration burden are associated with ATRX/TERT alterations and are suitable prognostic markers. Transcriptomic analysis defines the signaling networks involved in the acquisition of metastatic competence and establishes a gene signature related to mPPGLs, highlighting CDK1 as an additional mPPGL marker. Immunogenomics accompanied by immunohistochemistry identifies a heterogeneous ecosystem at the tumor microenvironment level, linked to the genomic subtype and tumor behavior. Specifically, we define a general immunosuppressive microenvironment in mPPGLs, the exception being PD-L1 expressing MAML3-related tumors. Our study reveals canonical markers for risk of metastasis, and suggests the usefulness of including immune parameters in clinical management for PPGL prognostication and identification of patients who might benefit from immunotherapy.

Same-day comparative protocol PET/CT-PET/MRI [68 Ga]Ga-DOTA-TOC in paragangliomas and pheochromocytomas: an approach to personalized medicine.

BACKGROUND: PET/MRI is an emerging imaging modality which enables the evaluation and quantification of biochemical processes in tissues, complemented with accurate anatomical information and low radiation exposure. In the framework of theragnosis, PET/MRI is of special interest due to its ability to delineate small lesions, adequately quantify them, and therefore to plan targeted therapies. The aim of this study was to validate the diagnostic performance of [68 Ga]Ga-DOTA-TOC PET/MRI compared to PET/CT in advanced disease paragangliomas and pheochromocytomas (PGGLs) to assess in which clinical settings, PET/MRI may have a greater diagnostic yield. METHODS: We performed a same-day protocol with consecutive acquisition of a PET/CT and a PET/MRI after a single [68 Ga]Ga-DOTA-TOC injection in 25 patients. Intermodality agreement, Krenning Score (KS), SUVmax (Standard Uptake Value), target-to-liver-ratio (TLR), clinical setting, location, and size were assessed. RESULTS: The diagnostic accuracy with PET/MRI increased by 14.6% compared to PET/CT especially in bone and liver locations (mean size of new lesions was 3.73 mm). PET/MRI revealed a higher overall lesion uptake than PET/CT (TLR 4.12 vs 2.44) and implied an upward elevation of the KS in up to 60% of patients. The KS changed in 30.4% of the evaluated lesions (mean size 11.89 mm), in 18.4% of the lesions it increased from KS 2 on PET/CT to a KS ≥ 3 on PET/MRI and 24.96% of the lesions per patient with multifocal disease displayed a KS ≥ 3 on PET/MR, that were not detected or showed lower KS on PET/CT. In 12% of patients, PET/MRI modified clinical management. CONCLUSIONS: PET/MRI showed minor advantages over conventional PET/CT in the detection of new lesions but increased the intensity of SSRs expression in a significant number of them, opening the door to select which patients and clinical settings can benefit from performing PET/MRI.

Impact of Diabetes Mellitus in Patients with Pancreatic Neuro-Endocrine Tumors: Causes, Consequences, and Future Perspectives.

Diabetes mellitus (DM) and pancreatic neuroendocrine tumors (pNETs) are two entities closely linked together. DM has been described as a risk factor for the development of pNETs and for the aggressiveness of the disease. On the other hand, DM due to pNETs is frequently undiagnosed or misclassified as type 2 DM when it is due to type 3 DM. In addition, metformin, a commonly prescribed drug for type 2 DM, has an antiproliferative property and is gaining increasing attention as an antitumor agent. This review article presents the findings published in the last few years on pNETs and DMs. Emphasis will be placed on DM as a risk factor, pNET as a risk factor for the development of type 3 DM, the management of type 3 DM on pNET, and DM as a prognostic factor in patients with pNET, as well as the future clinical implications of DM in these patients. The coexistence of DM and pNET is extensively presented. It is important to perform future clinical trials, which are necessary to establish the role of metformin on pNET disease. Increasing awareness among professionals managing pNET on the importance of a correct DM diagnosis and management of the disease must be a priority due to the implications on mortality and comorbidities it may have in these patients.

Response to targeted radionuclide therapy with [131I]MIBG AND [177Lu]Lu-DOTA-TATE according to adrenal vs. extra-adrenal primary location in metastatic paragangliomas and pheochromocytomas: A systematic review.

Purpose: Targeted radionuclide therapy (TRT) with [131I]MIBG and [177Lu]Lu-DOTA-TATE is an alternative treatment to the classic schemes in slow progressive metastatic/inoperable paraganglioma (PGL) and pheochromocytoma (PHEO). There is no consensus on which treatment to administer and/or the best sequence in patients who are candidates for both therapies. To clarify these questions, this systematic review assesses the prognostic value of [131I]MIBG and [177Lu]Lu-DOTA-TATE (PRRT-Lu) treatments in terms of progression-free survival (PFS) both globally and considering the primary location. Methods: This review was developed according to the PRISMA Statement with 27 final studies (608 patients). Patient characteristics, treatment procedure, and follow-up criteria were evaluated. In addition, a Bayesian linear regression model weighted according to its sample size and an alternative model, which also included an interaction between the treatment and the proportion of PHEOs, were carried out, adjusted by a Student's t distribution. Results: In linear regression models, [131I]MIBG overall PFS was, on average, 10 months lower when compared with PRRT-Lu. When considering the interaction between treatment responses and the proportion of PHEOs, PRRT-Lu showed remarkably better results in adrenal location. The PFS of PRRT-Lu was longer when the ratio of PHEOs increased, with a decrease in [131I]MIBG PFS by 1.9 months for each 10% increase in the proportion of PHEOs in the sample. Conclusion: Methodology, procedure, and PFS from the different studies are quite heterogeneous. PRRT-Lu showed better results globally and specifically in PHEOs. This fact opens the window to prospective trials comparing or sequencing [131I]MIBG and PRRT-Lu.

Management of incidentally discovered appendiceal neuroendocrine tumors after an appendicectomy.

Appendiceal neuroendocrine tumors (aNETs) are an uncommon neoplasm that is relatively indolent in most cases. They are typically diagnosed in younger patients than other neuroendocrine tumors and are often an incidental finding after an appendectomy. Although there are numerous clinical practice guidelines on management of aNETs, there is continues to be a dearth of evidence on optimal treatment. Management of these tumors is stratified according to risk of locoregional and distant metastasis. However, there is a lack of consensus regarding tumors that measure 1-2 cm. In these cases, some histopathological features such as size, tumor grade, presence of lymphovascular invasion, or mesoappendix infiltration must also be considered. Computed tomography or magnetic resonance imaging scans are recommended for evaluating the presence of additional disease, except in the case of tumors smaller than 1 cm without additional risk factors. Somatostatin receptor scintigraphy or positron emission tomography with computed tomography should be considered in cases with suspected residual or distant disease. The main point of controversy is the indication for performing a completion right hemicolectomy after an initial appendectomy, based on the risk of lymph node metastases. The main factor considered is tumor size and 2 cm is the most common threshold for indicating a colectomy. Other factors such as mesoappendix infiltration, lymphovascular invasion, or tumor grade may also be considered. On the other hand, potential complications, and decreased quality of life after a hemicolectomy as well as the lack of evidence on benefits in terms of survival must be taken into consideration. In this review, we present data regarding the current indications, outcomes, and benefits of a colectomy.

[177Lu]Lu-DOTA-TATE and [131I]MIBG Phenotypic Imaging-Based Therapy in Metastatic/Inoperable Pheochromocytomas and Paragangliomas: Comparative Results in a Single Center.

Purpose: The aim of the study is to assess phenotypic imaging patterns and the response to treatment with [177Lu]Lu-DOTA-TATE and/or [131I]MIBG in paragangliomas (PGLs) and pheochromocytomas (PHEOs), globally and according to the primary location. Methods: This is a 17-patient retrospective observational study, with 9 cases treated with [177Lu]Lu-DOTA-TATE and 8 with [131I]MIBG (37 total treatments). Functional imaging scans and treatment responses were studied in order to choose the best therapeutic option and to define the progression-free survival (PFS) and disease control rate (DCR) according to treatment modality and primary location. Results: All patients were studied with phenotypic nuclear medicine images. Twelve of 17 patients were tested with both [123I]MIBG and somatostatin receptor images, and 6/12 showed appropriate expression of both targets to treatment in the phenotypic images. The rest of the patients were tested with one of the image modalities or only showed suitable uptake of a single radiotracer and were treated with the corresponding therapeutic option. [177Lu]Lu-DOTA-TATE PFS was 29 months with a DCR of 88.8%. [131I]MIBG PFS was 18.5 months with a 62.5% DCR. According to the primary location, the best PFS was in PHEOs treated with [177Lu]Lu-DOTA-TATE. Although the series are small due to the low disease prevalence and do not allow to yield statistically significant differences, this first study comparing [177Lu]Lu-DOTA-TATE and [131I]MIBG displays a trend to an overall longer PFS with [177Lu]Lu-DOTA-TATE, especially in the adrenal primary location. When both radionuclide targets are expressed, the patients' comorbidity and treatment effectiveness should be valued together with the intensity uptake in the phenotypic image in order to choose the best therapeutic option. These preliminary retrospective results reinforce the need for a prospective, multicentric trial to be confirmed.

Somatostatin and Somatostatin Receptors: From Signaling to Clinical Applications in Neuroendocrine Neoplasms.

Neuroendocrine neoplasms (NENs) are heterogeneous neoplasms which arise from neuroendocrine cells that are distributed widely throughout the body. Although heterogenous, many of them share their ability to overexpress somatostatin receptors (SSTR) on their cell surface. Due to this, SSTR and somatostatin have been a large subject of interest in the discovery of potential biomarkers and treatment options for the disease. The aim of this review is to describe the molecular characteristics of somatostatin and somatostatin receptors and its application in diagnosis and therapy on patients with NENs as well as the use in the near future of somatostatin antagonists.

Prevention and Management of Hormonal Crisis during Theragnosis with LU-DOTA-TATE in Neuroendocrine Tumors. A Systematic Review and Approach Proposal.

Neuroendocrine tumors (NETs) frequently overexpress somatostatin receptors (SSTR) on their cell surface. The first-line pharmacological treatment for inoperable metastatic functioning well-differentiated NETs are somatostatin analogs. On second line, Lu-DOTA-TATE (177Lu-DOTA0 Tyr 3 octreotate) has shown stabilization of the disease and an increase in progression free survival, as well as effectiveness in controlling symptoms and increasing quality of life. The management of functional NETs before and during LU-DOTA-TATE treatment is specially challenging, as several complications such as severe carcinoid and catecholamine crisis have been described. The aim of this review is to establish practical guidance for the management and prevention of the most common hormonal crises during radionuclide treatment with Lu-DOTA-TATE: carcinoid syndrome (CS) and catecholamine hypersecretion, as well as to provide a brief commentary on other infrequent metabolic complications. To establish a practical approach, a systematic review was performed. This systematic review was developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and conducted using MEDLINE (accessed from PubMed), Google Scholar and ClinicalTrials.gov. Literature searches found 449 citations, and finally nine were considered for this systematic review.

Autoimmune Diabetes Recurrence After Pancreas Transplantation: Diagnosis, Management, and Literature Review.

BACKGROUND Pancreas transplantation can be a viable treatment option for patients with type 1 diabetes mellitus (T1DM), especially for those who are candidates for kidney transplantation. T1DM may rarely recur after pancreas transplantation, causing the loss of pancreatic graft. The aim of this study was to describe the prevalence of T1DM recurrence after pancreas transplantation in our series. MATERIAL AND METHODS Eighty-one patients transplanted from 2002 to 2015 were included. Autoantibody testing (GADA and IA-2) was performed before pancreas transplantation and during the follow-up. RESULTS The series includes 48 males and 33 females, mean age 37.4±5.7 years and mean duration of diabetes 25.5±6.5 years. Patients received simultaneous pancreas kidney (SPK) transplantation. After SPK transplantation, 56 patients retained pancreatic graft, 8 patients died, and 17 patients lost their pancreatic graft. T1DM recurrence occurred in 2 of the 81 transplanted patients, yielding a prevalence of 2.5%, with an average time of appearance of 3.3 years after transplant. Pancreatic enzymes were normal in the 2 patients, ruling out pancreatic rejection. T1DM recurrence was confirmed histologically, showing selective lymphoid infiltration of the pancreatic islets. CONCLUSIONS T1DM recurrence after pancreas transplantation is infrequent; however, it is one of the causes of pancreatic graft loss that should always be ruled out. Negative autoimmunity prior to transplantation does not ensure that T1DM does not recur.

Alterations of the female reproductive system in islet recipient receiving immunosuppression.

Pancreatic islet allotransplantation is an option for patients with unstable type 1 diabetes mellitus (T1DM). Major improvements in islet isolation techniques and the implementation of steroid-free immunosuppressive regimens can maintain insulin independence in the majority of T1DM for at least 1 year after transplantation. Recent studies have emphasized the impact of sirolimus on female reproductive tract. In this communication we report on the alterations of the female reproductive tract in 18 chronically immunosuppressed patients with T1DM following allogenic islet transplantation. Previous research has shown development of ovarian cysts in islet transplant patients receiving sirolimus. We extensively reevaluated this and other possible side effects on the female reproductive system. These side effects have been underestimated, although they are significant, requiring surgical or intensive medical treatment. Pre- and posttransplant gynecological evaluation should be performed to address the development of complications secondary to sirolimus in order to intervene sooner with alternative therapies.

Hypogonadotropic hypogonadism in a patient with morbid obesity.

Obesity has recently become one of the most important public health problems. It is associated with a high rate of mortality, mainly because of cardiovascular disease, and can cause hormonal abnormalities such as hypogonadotropic hypogonadism. Weight loss is very beneficial for obese patients, because it results in improvement or even normalization of these conditions. In this report, we describe a morbidly obese patient with hypogonadotropic hypogonadism, which was probably caused by hyperprolactinemia and exacerbated by obesity-induced hormonal imbalances. After medical treatment for hyperprolactinemia and bariatric surgery, the patient's hormonal status became normal. Although morbid obesity can cause hypogonadotropic hypogonadism in men, the differential diagnosis should include other potential causes of hypogonadism if free testosterone levels are below normal.