Importance of Immunohistochemical Detection of Somatostatin Receptors

Aggressive Variant of Hepatic Epstein-Barr Virus-Associated Inflammatory Pseudotumor-like Follicular Dendritic Cell Sarcoma with PD-L1 and SSTR2a Expression

An aggressive Epstein-Barr virus (EBV)-associated inflammatory pseudotumor-like follicular dendritic cell (IPT-like FDC) sarcoma is reported in an adult female. The patient developed multifocal recurrence and passed away 13 months after the initial surgical resection. A bright field microscopic examination of the tumor demonstrated a classical growth pattern and the diffuse expression of Programmed death ligand 1 (PD-L1) and somatostatin receptor 2a (SSTR2a).

Combination Systemic Therapies in Advanced Well-Differentiated Gastroenteropancreatic Neuroendocrine Tumors (GEP-NETs): A Comprehensive Review of Clinical Trials and Prospective Studies

There is an evolving landscape of systemic combination regimens for patients with advanced well-differentiated gastroenteropancreatic neuroendocrine tumors (GEP-NETs). In this review, we provide a comprehensive outline of the existing clinical trials/prospective studies investigating these combinations. PubMed was searched using key relevant terms to identify articles referring to GEP-NETs and combination treatments. No systematic search of the literature or metanalysis of the data was performed, and we focused on the most recent literature results. Primarily, phase 1 and 2 clinical trials were available, with a smaller number of phase 3 trials, reporting results from combination treatments across a wide range of antiproliferative agents. We identified significant variability in the anti-tumor activity of the reported combinations, with occasional promising results, but only a very small number of practice-changing phase 3 clinical trials. Overall, the peptide receptor radionuclide therapy (PRRT)-based combinations (with chemotherapy, dual PPRT, and targeted agents) and anti-vascular endothelial growth factor (VEGF) agent combinations with standard chemotherapy were found to have favorable results and may be worth investigating in future, larger-scale trials. In contrast, the immune-checkpoint inhibitor-based combinations were found to have limited applicability in advanced, well-differentiated GEP-NETs.

Neuroendocrine neoplasms in the context of inherited tumor syndromes: a reappraisal focused on targeted therapies

PURPOSE

Neuroendocrine neoplasms can occur as part of inherited disorders, usually in the form of well-differentiated, slow-growing tumors (NET). The main predisposing syndromes include: multiple endocrine neoplasias type 1 (MEN1), associated with a large spectrum of gastroenteropancreatic and thoracic NETs, and type 4 (MEN4), associated with a wide tumour spectrum similar to that of MEN1; von Hippel-Lindau syndrome (VHL), tuberous sclerosis (TSC), and neurofibromatosis 1 (NF-1), associated with pancreatic NETs. In the present review, we propose a reappraisal of the genetic basis and clinical features of gastroenteropancreatic and thoracic NETs in the setting of inherited syndromes with a special focus on molecularly targeted therapies for these lesions.

METHODS

Literature search was systematically performed through online databases, including MEDLINE (via PubMed), and Scopus using multiple keywords' combinations up to June 2022.

RESULTS

Somatostatin analogues (SSAs) remain the mainstay of systemic treatment for NETs, and radiolabelled SSAs can be used for peptide-receptor radionuclide therapy for somatostatin receptor (SSTR)-positive NETs. Apart of these SSTR-targeted therapies, other targeted agents have been approved for NETs: the mTOR inhibitor everolimus for lung, gastroenteropatic and unknown origin NET, and sunitinib, an antiangiogenic tyrosine kinase inhibitor, for pancreatic NET. Novel targeted therapies with other antiangiogenic agents and immunotherapies have been also under evaluation.

CONCLUSIONS

Major advances in the understanding of genetic and epigenetic mechanisms of NET development in the context of inherited endocrine disorders have led to the recognition of molecular targetable alterations, providing a rationale for the implementation of treatments and development of novel targeted therapies.

Divergent impact of gestational diabetes mellitus between the thoracic and abdominal rat aorta: Influence of endothelium and angiotensin II receptors

Gestational diabetes mellitus (GDM) affects 5-10% of pregnancies and increases the risk of fetal and maternal adverse outcomes. Interestingly, the vascular response to AngII is decreased by pregnancy while the response is increased by diabetes. It remains unclear how GDM affects vascular tone and how angiotensin II receptors contribute to these changes. In this work, we sought to establish the vascular impact of a hypercaloric diet-induced GDM through changes in AT1 and AT2 receptor's expression. Female rats fed for 7 weeks with standard (SD) or hypercaloric (HD) diet were divided at week 4. Half of the rats of each group were mated to become pregnant and those fed with a HD developed GDM. AngII-induced vasoconstriction was measured in thoracic or abdominal aorta rings using a conventional isolated organ bath and AT1 and AT2 receptors were searched by immunohistochemistry. Experiments where conducted on the pregnant standard diet group (PSD) and the pregnant hypercaloric-gestational diabetes mellitus group (PHD-GDM). Vasoconstriction was reduced in the thoracic aorta (P < 0.05 vs PSD) but increased in the abdominal aorta of PHD-GDM rats (P < 0.05 vs PSD). Blockade of AT2 receptors using PD123319 decreased vasoconstriction, particularly in the abdominal aorta of PHD-GDM animals (P < 0.05 vs PSD). PHD-GDM increased AT1 receptors expression (P < 0.05 vs PSD). Also, PHD-GDM reverted physiologic hypoglycemia and hypotension of healthy pregnancy. Findings provide new insight into the hypercaloric diet induced damage on the vasculature during pregnancy.

Antiproliferative Effect of Above-Label Doses of Somatostatin Analogs for the Management of Gastroenteropancreatic Neuroendocrine Tumors

BACKGROUND

Above-label doses of somatostatin analogs (SSAs) are increasingly utilized in the management of inoperable/metastatic gastroenteropancreatic neuroendocrine tumors (GEP-NETs), progressing on standard 4-weekly regimens.

OBJECTIVE

To evaluate the antiproliferative effect of 3-weekly SSA administration in a retrospective GEP-NET cohort.

METHODS

Patients with advanced GEP-NET, treated with long-acting release (LAR) octreotide 30 mg or lanreotide Autogel 120 mg at a 3-weekly interval, after disease progression on standard 4-weekly doses, were retrospectively identified. Clinicopathologic and treatment response data were collected. Progression-free survival (PFS; dose escalation to radiographic progression or death) was estimated with the Kaplan-Meier method. Factors associated with PFS were identified with the Cox proportional-hazards model.

RESULTS

The inclusion criteria were fulfilled by 105 patients. Octreotide LAR was administered to 60 (57%) and lanreotide Autogel to 45 (43%). Indications for dose escalation were breakthrough carcinoid symptoms (58%), radiographic progression (35%) and/or increasing biomarkers (11%). Diarrheal and/or flushing symptomatic improvement was identified in 37/67 cases (55%) and 30/55 cases (55%) with available data, respectively. The disease control rate (radiographic partial response or stable disease) was achieved in 53 patients (50%). Median PFS was 25.0 months (95% CI 16.9-33.1). Patients with radiographic progression <12 months from 4-weekly SSA initiation had worse PFS after dose escalation (7.0 vs. 17.0 months, p = 0.002). In multivariate analysis, pancreatic NETs, a Ki-67 index ≥5% and multiple extrahepatic metastases were independently associated with inferior PFS.

CONCLUSIONS

Above-label doses of SSAs may offer a considerable prolongation of PFS and could be utilized as a bridge to other more toxic treatments. Patients with small bowel/colorectal primaries, a Ki-67 index <5% and absence of/limited extrahepatic metastases are more likely to benefit from this approach.

SSTR2a is constantly expressed in lymphoepithelioma-like carcinoma with squamous differentiation other than that with glandular differentiation

AIMS

Somatostatin receptor 2a (SSTR2a) is an important diagnostic marker of meningioma and neuroendocrine tumours and is frequently expressed in primary and metastatic non-keratinising nasopharyngeal carcinoma (NK-NPC). Since NK-NPC cases are considered a kind of lymphoepithelioma-like carcinoma (LELCs) which originate from the nasopharynx, information on the expression profile of SSTR2a in LELC in other sites with squamous and glandular differentiations is still lacking. This study aimed to assess the expression of SSTR2a in LELC of various organs and clarify its expression profile.

METHODS

Expression of SSTR2a in 164 cases of LELC was retrospectively analysed by immunohistochemistry in paraffin-embedded tissues, including 146 cases of LELC with squamous differentiation (120 cases of the nasopharynx, 21 cases of the lung and 5 cases of the parotid gland) and 18 cases of LELC with glandular differentiation (15 cases of the stomach and 3 cases of the liver).

RESULTS

We found that all (100%) cases of LELC of the lung (21/21) and parotid gland (5/5), and 93.3% (112/120) cases of LELC of the nasopharynx showed a diffused and strong expression of SSTR2a, while cases of gastric (0/15) and biliary (0/3) showed no SSTR2a expression.

CONCLUSION

SSTR2a is constantly expressed in LELC with squamous differentiation, but not expressed in LELC with glandular differentiation. However, the selective expression mechanism of SSTR2a remains unknown, which needs further investigation. Our novel findings might provide potential therapeutic approaches for the treatment of LELC with squamous cell differentiation.

Expression of potential therapeutic target SSTR2a in primary and metastatic non-keratinizing nasopharyngeal carcinoma

Somatostatin receptor 2a (SSTR2a) is an important diagnostic and scintigraphic marker in several tumors, as well as a potential therapeutic target. However, the expression and clinicopathologic significance of SSTR2a in nasopharyngeal carcinoma (NPC) remain unknown. The expression of SSTR2a was retrospectively analyzed in a large series of NPC tissue samples (106 primary NPC samples, comprising 99 primary non-keratinizing NPC (NK-NPC) and 7 keratinizing NPC (K-NPC) samples, and 41 metastatic NPC samples) by immunohistochemistry, with 24 cases of normal nasopharyngeal mucosa tissues used as a control group. Normal epithelia in nasopharyngeal mucosa were negative for SSTR2a in all 24 cases. The expression of SSTR2a in primary NPC was correlated to the histological subtype. Most cases of primary NK-NPC showed expression of SSTR2a (93.9%, 93/99 cases). The percentage of SSTR2a-positive tumor cells ranged from 10 to 100%, while the intensity ranged from 2+ to 4+. None of the primary K-NPC samples showed SSTR2a expression (0/7, 100%). All cases of NPC showed negative expression of other neuroendocrine markers, including synaptophysin, chromogranin A, and CD56. Of all 41 cases of metastatic NK-NPC lesions, SSTR2a expression is concordant with that of the primary lesions, which shows statistical significance (p < 0.001). Our observations expand the spectrum of recognized SSTR2a-positive tumors and demonstrate for the first time that SSTR2a is frequently expressed in primary and metastatic NK-NPC, highlighting its potential as a scintigraphic and therapeutic target in this disease.

Constant expression of somatostatin receptor 2a in minute pulmonary meningothelial-like nodules

Aims

Although ultrastructural studies showed that minute pulmonary meningothelial-like nodules (MPMNs) cells closely resembled meningothelial cells, their immunophenotype has not been well characterised, partly due to their rarity.

Methods

Somatostatin receptor 2a (SSTR2a) and other markers of meningioma, including epithelial membrane antigen (EMA), progesterone receptor (PR) and S100, were analysed retrospectively in 19 MPMN cases from two institutions in China.

Results

The median age of patients with MPMNs was 62.5 years (32–73 years), with a male-to-female ratio of 1:8.5. Most (15/19) patients with MPMNs had coexisting diseases, including adenocarcinomas (12 cases), bronchiectasis (1 case) and tuberculosis (2 cases). Just over half of the cases (10/19) were multifocal lesions (2–5 lesions). An additional 53 cases with 123 lesions from the literature were reviewed with reported immunophenotype information. In total, 162 lesions were included in the analysis. The size of nodules was 1–4 mm. All MPMN lesions (39/39) in the 19 cases showed strong and diffuse cytoplasmic expression of SSTR2a. The expression rate of SSTR2a was higher than that of conventional markers of meningioma, including EMA (86/138), PR (32/68) and S100 (1/125).

Conclusions

Our observations expand the spectrum of recognised SSTR2a-positive lesions and once again demonstrated that MPMNs show immunohistochemical characteristics similar to meningothelial cells.