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Somatostatin receptor 2A expression in von Hippel-Lindau-related hemangioblastomas
Abstract
Background
Central nervous system hemangioblastomas are the most prevalent manifestation of von Hippel‐Lindau (VHL) disease and remain the main cause of mortality. Surgical resection is the primary treatment strategy, but is not always possible, and should be used as restrictively as possible. There is an unmet need for less invasive treatment strategies, such as targeted therapy. Expression of somatostatin receptor 2A (SSTR2A) in VHL‐related hemangioblastomas has been described earlier, but the extent of expression in a larger population has yet to be determined. The authors hypothesize that a substantial subset of VHL‐related hemangioblastomas show SSTR2A expression, which may serve as a potential new treatment target.
Methods
Patients who were surgically treated for a VHL‐related hemangioblastoma from 1990 until 2021 at the UMC Utrecht were included. Clinical data was derived from a clinical database. Tissue samples were histopathologically examined with use of hematoxylin and eosin staining, and immunohistochemical analysis of SSTR2A expression was performed.
Results
Forty‐three tissue samples were obtained from 26 patients. Nine showed strong positivity for SSTR2A expression, whereas 13 showed moderate and 15 sparse expression. Three samples showed no expression of SSTR2A. The distribution showed right‐skewedness favoring a strong expression. SSTR2A expression colocalized with endothelial markers and not with stromal cells. Additionally, within‐patient variability for SSTR2A expression was described in 14 patients.
Conclusion
SSTR2A is expressed in varying degrees in the majority of VHL‐related hemangioblastomas. Future treatment with somatostatin analogues or even peptide receptor radionuclide treatment may be considered for SSTR2A‐positive cases.
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Patients with neuroendocrine tumors (NETs) can be treated with peptide receptor radionuclide therapy (PRRT). Here, the somatostatin analogue octreotate radiolabeled with lutetium-177 is targeted to NET cells by binding to the somatostatin receptor subtype 2 (SST2). During radioactive decay, DNA damage is induced, leading to NET cell death. Although the therapy proves to be effective, mortality rates remain high. To appropriately select more optimal treatment strategies, it is essential to first better understand the radiobiological responses of tumor cells to PRRT.
Methods: We analyzed PRRT induced radiobiological responses in SST2 expressing cells and xenografted mice using SPECT/MRI scanning and histological and molecular analyses. We measured [¹⁷⁷Lu]Lu-DOTA-TATE uptake and performed analyses to visualize induction of DNA damage, cell death and other cellular characteristics.
Results: The highest accumulation of radioactivity was measured in the tumor and kidneys. PRRT induced DNA damage signaling and repair in a time-dependent manner. We observed intra-tumor heterogeneity of DNA damage and apoptosis, which was not attributed to proliferation or bioavailability. We found a strong correlation between high DNA damage levels and high SST2 expression. PRRT elicited a different therapeutic response between models with different SST2 expression levels. Heterogeneous SST2 expression levels were also confirmed in patient NETs.
Conclusion: Heterogeneous SST2 expression levels within NETs cause differentially induced DNA damage levels, influence recurrent tumor phenotypes and impact the therapeutic response in different models and potentially in patients. Our results contribute to a better understanding of PRRT effects, which might impact future therapeutic outcome of NET patients.
Somatostatin analogs are an invaluable therapeutic option in the diagnosis and treatment of somatotropinomas, thyrotropinomas, and functioning and non-functioning gastroenteropancreatic neuroendocrine tumors. They should also be considered an effective and safe therapeutic alternative to corticotropinomas, gonadotropinomas, and prolactinomas resistant to dopamine agonists. Somatostatin analogs have also shown to be useful in the treatment of other endocrine diseases (congenital hyperinsulinism, Graves’ orbitopathy, diabetic retinopathy, diabetic macular edema), non-endocrine tumors (breast, colon, prostate, lung, and hepatocellular), and digestive diseases (chronic refractory diarrhea, hepatorenal polycystosis, gastrointestinal hemorrhage, dumping syndrome, and intestinal fistula).
p>Hemangioblastomas are rare and benign tumors accounting for less than 2% of all central nervous system (CNS) tumors. The vast majority of hemangioblastomas occur sporadically, whereas a small number of cases, especially in younger patients, are associated with Von Hippel–Lindau (VHL) syndrome. It is thought that loss of tumor suppressor function of the VHL gene results in stabilization of hypoxia-inducible factor alpha with downstream activation of cellular proliferative and angiogenic genes that promote tumorigenesis. VHL-related hemangioblastomas predominantly occur in the cerebellum and spine. Lesions are often diagnosed on contrast-enhanced craniospinal MRIs, and the diagnosis of VHL occurs through assessment for germline VHL mutations. Surgical resection remains the primary treatment modality for symptomatic or worrisome lesions, with excellent local control rates and neurological outcomes. Stereotactic radiotherapy can be employed in patients who are deemed high risk for surgery, have multiple lesions, or have non-resectable lesions. Given the tendency for development of either new or multiple lesions, close radiographic surveillance is often recommended for asymptomatic lesions.</p
Von Hippel-Lindau (VHL)-associated hemangioblastomas (VHL-HB) arise in the central nervous system (CNS), and are a leading cause of morbidity and mortality in VHL disease. Currently, surgical resection is the most effective way to manage symptomatic VHL-HBs. Surgically unresectable VHL-HBs or those in frail patients are challenging problems. Therapies targeting oncologic and vascular endothelial growth factor (VEGF) pathways have failed to demonstrate tumor control. Our experience and previous reports on VHL-HB avidity to somatostatin analogues suggested somatostatin receptor (SSTR) expression in VHL-HBs, offering an alternative therapeutic strategy. We explored this possibility by demonstrating consistent histologic expression of SSTR1, 2a, 4, and 5 in VHL-HBs. We found that somatostatin analogue octreotide induces apoptosis in VHL-HB stromal cells in a dose-dependent fashion by BAX – caspase-3 pathway unrelated to canonical VHL pathway. When administered to a patient with unresectable symptomatic suprasellar hemangioblastoma, octreotide resulted in tumor volume reduction, symptom stabilization, and tumor cytopenia on repeat ⁶⁸Ga-DOTA-TATE positron emission tomography (PET) within 6 months, suggesting tumor infarction. We conclude that VHL-HBs harbor multiple SSTR subtypes that offer actionable chemo-therapeutic strategy for management of symptomatic, unresectable tumors by somatostatin analogue therapy.
ETS-related gene (ERG) is a transcription factor that has been linked to angiogenesis. Very little research has been done to assess ERG expression in central nervous system (CNS) tumors. We evaluated 57 CNS tumors, including glioblastomas (GBMs) and hemangioblastomas (HBs), as well as two arteriovenous malformations and four samples of normal brain tissue with immunohistochemistry using a specific ERG rabbit monoclonal antibody. In addition, immunostains for CD31, CD34, and α-smooth muscle actin (α-SMA) were performed on all samples. CD31 demonstrated variable and sometimes weak immunoreactivity for endothelial cells. Furthermore, in 1 case of a GBM, CD34 stained not only endothelial cells, but also tumor cells. In contrast, we observed that ERG was only expressed in the nuclei of endothelial cells, for example, in the hyperplastic vascular complexes that comprise the glomeruloid microvascular proliferation seen in GBMs. Conversely, α-SMA immunoreactivity was identified in the abluminal cells of these hyperplastic vessels. Quantitative evaluation with automated methodology and custom Matlab 2008b software was used to calculate percent staining of ERG in each case. We observed significantly higher quantitative expression of ERG in HBs than in other CNS tumors. Our results show that ERG is a novel, reliable, and specific marker for endothelial cells within CNS tumors that can be used to better study the process of neovascularization.
Background:
Somatostatin analogues are commonly used to treat symptoms associated with hormone hypersecretion in neuroendocrine tumors; however, data on their antitumor effects are limited.
Methods:
We conducted a randomized, double-blind, placebo-controlled, multinational study of the somatostatin analogue lanreotide in patients with advanced, well-differentiated or moderately differentiated, nonfunctioning, somatostatin receptor-positive neuroendocrine tumors of grade 1 or 2 (a tumor proliferation index [on staining for the Ki-67 antigen] of <10%) and documented disease-progression status. The tumors originated in the pancreas, midgut, or hindgut or were of unknown origin. Patients were randomly assigned to receive an extended-release aqueous-gel formulation of lanreotide (Autogel [known in the United States as Depot], Ipsen) at a dose of 120 mg (101 patients) or placebo (103 patients) once every 28 days for 96 weeks. The primary end point was progression-free survival, defined as the time to disease progression (according to the Response Evaluation Criteria in Solid Tumors, version 1.0) or death. Secondary end points included overall survival, quality of life (assessed with the European Organization for Research and Treatment of Cancer questionnaires QLQ-C30 and QLQ-GI.NET21), and safety.
Results:
Most patients (96%) had no tumor progression in the 3 to 6 months before randomization, and 33% had hepatic tumor volumes greater than 25%. Lanreotide, as compared with placebo, was associated with significantly prolonged progression-free survival (median not reached vs. median of 18.0 months, P<0.001 by the stratified log-rank test; hazard ratio for progression or death, 0.47; 95% confidence interval [CI], 0.30 to 0.73). The estimated rates of progression-free survival at 24 months were 65.1% (95% CI, 54.0 to 74.1) in the lanreotide group and 33.0% (95% CI, 23.0 to 43.3) in the placebo group. The therapeutic effect in predefined subgroups was generally consistent with that in the overall population, with the exception of small subgroups in which confidence intervals were wide. There were no significant between-group differences in quality of life or overall survival. The most common treatment-related adverse event was diarrhea (in 26% of the patients in the lanreotide group and 9% of those in the placebo group).
Conclusions:
Lanreotide was associated with significantly prolonged progression-free survival among patients with metastatic enteropancreatic neuroendocrine tumors of grade 1 or 2 (Ki-67 <10%). (Funded by Ipsen; CLARINET ClinicalTrials.gov number, NCT00353496; EudraCT 2005-004904-35.).
Von Hippel-Lindau (VHL) disease is a dominantly inherited familial cancer syndrome with a variety of benign and malignant tumors such as retinal and central nervous system hemangioblastomas, endolymphatic sac tumors, renal cysts and tumors, pancreatic cysts and tumors, pheochromocytomas, and epididymal cystadenomas. Cross-sectional modalities (computed tomography and magnetic resonance imaging) as well as ultrasound play a major role in the initial evaluation and follow-up of the various manifestations of VHL disease. Ga-68-labeled somatostatin receptor analogs already have a significant role in the diagnosis, staging, and therapy management of neuroendocrine neoplasms and neural crest tumors. Herein, we report a case presenting a variety of malignancies in VHL and showing the usefulness of Ga-68 somatostatin receptor PET/CT as a one-stop-shop imaging modality in the management of VHL disease.
Somatostatin analogs are indicated for symptom control in patients with gastroenteropancreatic neuroendocrine tumors (NETs). The ability of somatostatin analogs to control the growth of well-differentiated metastatic NETs is a matter of debate. We performed a placebo-controlled, double-blind, phase IIIB study in patients with well-differentiated metastatic midgut NETs. The hypothesis was that octreotide LAR prolongs time to tumor progression and survival.
Treatment-naive patients were randomly assigned to either placebo or octreotide LAR 30 mg intramuscularly in monthly intervals until tumor progression or death. The primary efficacy end point was time to tumor progression. Secondary end points were survival time and tumor response. This report is based on 67 tumor progressions and 16 observed deaths in 85 patients at the time of the planned interim analysis.
Median time to tumor progression in the octreotide LAR and placebo groups was 14.3 and 6 months, respectively (hazard ratio [HR] = 0.34; 95% CI, 0.20 to 0.59; P = .000072). After 6 months of treatment, stable disease was observed in 66.7% of patients in the octreotide LAR group and 37.2% of patients in the placebo group. Functionally active and inactive tumors responded similarly. The most favorable effect was observed in patients with low hepatic tumor load and resected primary tumor. Seven and nine deaths were observed in the octreotide LAR and placebo groups, respectively. The HR for overall survival was 0.81 (95% CI, 0.30 to 2.18).
Octreotide LAR significantly lengthens time to tumor progression compared with placebo in patients with functionally active and inactive metastatic midgut NETs. Because of the low number of observed deaths, survival analysis was not confirmatory.
We hypothesized that non-proliferating (quiescent) human vascular endothelial cells would not express somatostatin receptor subtype 2 (sst 2) and that this receptor would be expressed when the endothelial cells begin to grow. To test this hypothesis, placental veins were harvested from 6 human placentas and 2 mm vein disks were cultured in 0.3% fibrin gels. Morphometric analysis confirmed that 50-75% of cultured vein disks developed radial capillary growth within 15 days. Sst 2 gene expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) analysis of the RNA from veins before culture and from tissue-matched vein disks that exhibited an angiogenic response. The sst 2 gene was expressed in the proliferating angiogenic sprouts of human vascular endothelium. The presence of sst 2 receptors on proliferating angiogenic vessels was confirmed by immunohistochemical staining and in vivo scintigraphy. These results suggest that sst 2 may be a unique target for antiangiogenic therapy with sst 2 preferring somatostatin analogues conjugated to radioisotopes or cytotoxic agents.
Although rare, a metastatic renal cell carcinoma could present with 68Ga-DOTATATE avidity. A 66-year-old man with von Hippel-Lindau syndrome (VHL) presented with 68Ga-DOTATATE uptake in the pancreatic head, splenic hilar region, and multiple osseous sites, including the right lateral portion of the T9 vertebrae. Biopsy of the T9 lesion confirmed metastatic renal cell carcinoma. Various VHL-associated cancers may display 68Ga-DOTATATE avidity, which can change and guide clinical decisions for the patient.
Background:
Patients with von Hippel-Lindau (VHL) disease have a high incidence of renal cell carcinoma owing to VHL gene inactivation and constitutive activation of the transcription factor hypoxia-inducible factor 2α (HIF-2α).
Methods:
In this phase 2, open-label, single-group trial, we investigated the efficacy and safety of the HIF-2α inhibitor belzutifan (MK-6482, previously called PT2977), administered orally at a dose of 120 mg daily, in patients with renal cell carcinoma associated with VHL disease. The primary end point was objective response (complete or partial response) as measured according to the Response Evaluation Criteria in Solid Tumors, version 1.1, by an independent central radiology review committee. We also assessed responses to belzutifan in patients with non-renal cell carcinoma neoplasms and the safety of belzutifan.
Results:
After a median follow-up of 21.8 months (range, 20.2 to 30.1), the percentage of patients with renal cell carcinoma who had an objective response was 49% (95% confidence interval, 36 to 62). Responses were also observed in patients with pancreatic lesions (47 of 61 patients [77%]) and central nervous system hemangioblastomas (15 of 50 patients [30%]). Among the 16 eyes that could be evaluated in 12 patients with retinal hemangioblastomas at baseline, all (100%) were graded as showing improvement. The most common adverse events were anemia (in 90% of the patients) and fatigue (in 66%). Seven patients discontinued treatment: four patients voluntarily discontinued, one discontinued owing to a treatment-related adverse event (grade 1 dizziness), one discontinued because of disease progression as assessed by the investigator, and one patient died (of acute toxic effects of fentanyl).
Conclusions:
Belzutifan was associated with predominantly grade 1 and 2 adverse events and showed activity in patients with renal cell carcinomas and non-renal cell carcinoma neoplasms associated with VHL disease. (Funded by Merck Sharp and Dohme and others; MK-6482-004 ClinicalTrials.gov number, NCT03401788.).
Purpose
Patients with von Hippel-Lindau (VHL) disease may develop various tumors, including neuroendocrine tumors of the pancreas (PNETs) and adrenal, central nervous system and retinal hemangioblastomas, kidney tumors and more. ⁶⁸Ga-DOTATATE positron emission tomography (PET)/computerized tomography (CT) has been shown to be highly accurate for tumors with cells expressing somatostatin receptors. We aimed to assess the performance of ⁶⁸Ga-DOTATATE PET/CT in patients with VHL disease.
Methods
Patients with a diagnosis of VHL were enrolled in a prospective study and underwent surveillance imaging for pancreatic lesions (n = 301). The current analysis includes 73 evaluations with multiple imaging modalities of 36 patients (2.1 ± 0.8 evaluations/patient, range 1–4) for a head-to-head comparison of ⁶⁸Ga-DOTATATE PET/CT, CT and/or MRI. In this post-hoc analysis we compared the detection rates of various imaging modalities for PNETs and for any extrapancreatic tumors located within the scan field of CT/MRI of the abdomen.
Results
⁶⁸Ga-DOTATATE PET/CT detected a total of 206 lesions, CT detected 208 lesions and MRI detected 94 lesions in 61, 66 and 33 scans, respectively. ⁶⁸Ga-DOTATATE PET/CT (3.4 ± 0.1 per scan) was superior than CT (3.2 ± 0.1 per scan, p = 0.02) with a similar trend when comparing with MRI (2.8 ± 0.1 per scan, p = 0.03) in detecting lesions in any anatomic locations.
Conclusions
⁶⁸Ga-DOTATATE PET/CT had a significantly higher detection rate when compared with anatomic imaging for all lesions, and comparable detection rate for pancreatic lesions in VHL patients. Hence, given the higher accuracy and lower radiation exposure associated with ⁶⁸Ga-DOTATATE PET/CT, its potential role in the surveillance of VHL-associated lesions should be further studied.
Objective:
Somatostatin receptors (SSTRs), products of gene superfamily SSTR1-5, are commonly expressed in neuroendocrine tumors (NETs). Somatostatin analogs (SSAs) bind to SSTRs and are used as therapeutic agents in patients with advanced NETs. We hypothesized that tumor SSTR expression status would be associated with clinical outcomes in NET.
Methods:
Expression of the 5 SSTRs was evaluated by immunohistochemistry, using tissue microarrays comprising 173 primary NETs, 24 matched metastases, and 22 metastatic NETs from 195 patients. Cox proportional hazards regression analysis was used to assess the association of SSTR expression status (high vs low) with clinical outcomes, adjusting for potential confounders.
Results:
High expression of SSTR2 was associated with longer overall survival (OS) in the cohort overall (multivariate hazard ratio, 0.42; 95% confidence interval, 0.21-0.84; P = 0.013). In a subgroup of patients with metastatic small intestine NET treated with SSAs and evaluable for progression, SSTR2 expression was associated with both longer progression-free survival (PFS) and OS. No associations with PFS or OS were observed with expression of other SSTRs.
Conclusions:
Our study demonstrated that expression of SSTR2, but not other SSTRs, is associated with longer OS. In patients treated with SSAs, expression of SSTR2 is associated with longer PFS survival.
von Hippel-Lindau (VHL) disease is a familial cancer syndrome characterized by the development of a variety of malignant and benign tumors, including epididymal cystadenomas. We report a case of a VHL patient with bilateral epididymal cystadenomas who was evaluated with Ga DOTATATE PET/CT, showing intensely increased activity (SUVmax, 21.6) associated with the epididymal cystadenomas, indicating cell-surface overexpression of somatostatin receptors. The presented case supports the usefulness of somatostatin receptor imaging using Ga DOTA-conjugated peptides for detection and follow-up of VHL manifestations, as well as surveillance of asymptomatic gene carriers.
Endolymphatic sac tumors (ELSTs) are rare tumors arising from the epithelium of the endolymphatic sac and duct that can be either sporadic or associated with von Hippel-Lindau (VHL) disease. We report a case of a VHL patient with histologically proven residual ELST who underwent Ga DOTATATE PET/CT showing increased activity (SUVmax, 6.29) by the ELST. The presented case of a VHL-associated ELST with increased Ga DOTATATE uptake indicates cell-surface expression of somatostatin receptors by this tumor, suggesting the potential application of somatostatin receptor imaging using Ga DOTA-conjugated peptides in the workup and management of these patients.
Since its discovery three decades ago as an inhibitor of GH release from the pituitary gland, somatostatin has attracted much attention because of its functional role in the regulation of a wide variety of physiological functions in the brain, pituitary, pancreas, gastrointestinal tract, adrenals, thyroid, kidney and immune system. Its actions include inhibition of endocrine and exocrine secretions, modulation of neurotransmission, motor and cognitive functions, inhibition of intestinal motility, absorption of nutrients and ions and vascular contractility. In addition, the peptide controls the proliferation of normal and tumor cells. Its action is mediated by a family of G protein-coupled receptors [somatostatin receptor (SSTR)1-SSTR5] that are widely distributed in normal and cancer cells. Direct antitumor activities, mediated through SSTR expressed in tumor cells, include blockade of autocrine/paracrine growth-promoting hormone and growth factor production, inhibition of growth factor-mediated mitogenic signals and induction of apoptosis. Indirect antitumor effects include inhibition of growth-promoting hormone and growth factor secretion, and antiangiogenic actions. Many human tumors express more than one SSTR subtype, with SSTR2 being predominant. These receptors represent the molecular basis for the clinical use of somatostatin analogs in the treatment of endocrine tumors and their in vivo localization. This review covers the present knowledge in SSTR biology and signaling.
A 35-year-old man with clinical suspicion of adrenal pheochro-mocytoma was evaluated using 68 Ga DOTANOC PET/CT. PET/CT demon-strated 68 Ga DOTANOCYavid right adrenal mass and cerebellar lesion, raising the suspicion of adrenal pheochromocytoma with cerebellar hemangioblastoma suggesting von Hippel-Lindau (VHL) syndrome. Cerebellar lesion on further evaluation with MRI was suggestive of cerebellar hemangioblastoma. Surgical resection of the adrenal mass revealed pheochromocytoma, and genetic analysis revealed mutation involving the chromosome 3p, confirming the diagnosis of VHL syndrome. 68
A case of Von-Hippel Lindau (VHL) disease has been studied using 68Ga-DOTA-NOC PET/CT. PET/CT demonstrated the presence of somatostatin receptors within 2 focal areas in the cerebellum corresponding to the lesions detected by MRI. Considering the heterogeneous lesions localizations in VHL disease, PET/CT may be a useful imaging modality for diagnosing lesions of central nervous system and neuroendocrine lesions and for direct demonstration of somatostatin receptors for targeted treatment.
The goals of this study were to define the natural history and growth pattern of hemangioblastomas of the central nervous system (CNS) that are associated with von Hippel-Lindau (VHL) disease and to correlate features of hemangioblastomas that are associated with the development of symptoms and the need for treatment.
The authors reviewed serial magnetic resonance images and clinical histories of 160 consecutive patients with VHL disease who harbored CNS hemangioblastomas and serially measured the volumes of tumors and associated cysts Six hundred fifty-five hemangioblastomas were identified in the cerebellum (250 tumors), brainstem (64 tumors, all of which were located in the posterior medulla oblongata), spinal cord (331 tumors, 96% of which were located in the posterior half of spinal cord), and the supratentorial brain (10 tumors). The symptoms were related to a mass effect. A serial increase in hemangioblastoma size was observed in cerebellar, brainstem, and spinal cord tumors as patients progressed from being asymptomatic to symptomatic and requiring surgery (p < 0.0001). Twenty-one (72%) of 29 symptom-producing cerebellar tumors had an associated cyst, whereas only 28 (13%) of 221 nonsymptomatic cerebellar tumors had tumor-associated cysts (p < 0.0001). Nine (75%) of 12 symptomatic brainstem tumors had associated cysts, compared with only four (8%) of 52 nonsymptomatic brainstem lesions (p < 0.0001). By the time the symptoms appeared and surgery was required, the cyst was larger than the causative tumor; cerebellar and brainstem cysts measured 34 and 19 times the size of their associated tumors at surgery, respectively. Ninety-five percent of symptom-producing spinal hemangioblastomas were associated with syringomyelia. The clinical circumstance was dynamic. Among the 88 patients who had undergone serial imaging for 6 months or longer (median 32 months), 164 (44%) of 373 hemangioblastomas and 37 (67%) of 55 tumor-associated cysts enlarged. No tumors or cysts spontaneously diminished in size. Symptomatic cerebellar and brainstem tumors grew at rates six and nine times greater, respectively, than asymptomatic tumors in the same regions. Cysts enlarged seven (cerebellum) and 15 (brainstem) times faster than the hemangioblastomas causing them. Hemangioblastomas frequently demonstrated a pattern of growth in which they would enlarge for a period of time (growth phase) and then stabilize in a period of arrested growth (quiescent phase). Of 69 patients with documented tumor growth, 18 (26%) harbored tumors with at least two growth phases. Of 160 patients with hemangioblastomas, 34 patients (median follow up 51 months) were found to have 115 new hemangioblastomas and 15 patients new tumor-associated cysts.
In this study the authors define the natural history of CNS hemangioblastomas associated with VHL disease. Not only were cysts commonly associated with cerebellar, brainstem, and spinal hemangioblastomas, the pace of enlargement was much faster for cysts than for hemangioblastomas. By the time symptoms appeared, the majority of mass effect-producing symptoms derived from the cyst, rather than from the tumor causing the cyst. These tumors often have multiple periods of tumor growth separated by periods of arrested growth, and many untreated tumors may remain the same size for several years. These characteristics must be considered when determining the optimal timing of screening for individual patients and for evaluating the timing and results of treatment.
von Hippel-Lindau disease is a heritable multisystem cancer syndrome that is associated with a germline mutation of the VHL tumour suppressor gene on the short arm of chromosome 3. This disorder is not rare (about one in 36000 livebirths) and is inherited as a highly penetrant autosomal dominant trait (ie, with a high individual risk of disease). Affected individuals are at risk of developing various benign and malignant tumours of the central nervous system, kidneys, adrenal glands, pancreas, and reproductive adnexal organs. Because of the complexities associated with management of the various types of tumours in this disease, treatment is multidisciplinary. We present an overview of the clinical aspects, management, and treatment options for von Hippel-Lindau disease.
Somatostatin receptors are expressed in selected human cancers. They are particularly frequently expressed in gastroenteropancreatic neuroendocrine tumors (GEP NET), including both primaries and metastases. The density is often high, the distribution is usually homogeneous. While various somatostatin receptor subtypes can be expressed in these tumors, sst2 is clearly predominant. These receptors represent the molecular basis for a number of clinical applications, including symptomatic therapy with cold octreotide in hormone-secreting GEP NET, in vivo diagnostic with Octreoscan to evaluate the extend of the disease, and 90Y-DOTATOC radiotherapy. GEP NET can, however, express peptide receptors other than somatostatin receptors: insulinomas have more glucagon-like peptide 1 receptors than somatostatin receptors, gut NET (carcinoids) may also express cholecystokinin 2, bombesin or vasoactive intestinal peptide receptors. Often, several of these peptide receptors are expressed simultaneously in GEP NET, providing a molecular basis for in vivo multireceptor targeting of those tumors.
A 38-year-old woman with known von Hippel-Lindau syndrome underwent In-111 pentetreotide (OctreoScan) scintigraphy to evaluate a suspected pancreatic neuroendocrine tumor. The patient had undergone surgical resection of a left adrenal pheochromocytoma and a large right cerebellar hemangioblastoma several years previously. Although there was no evidence for recurrence of pheochromocytoma and no uptake within the pancreatic lesion, there was focal tracer accumulation within the left cerebellar hemisphere. MR imaging of the brain confirmed the presence of recurrent hemangioblastoma in the left cerebellum.
Since its discovery three decades ago as an inhibitor of GH release from the pituitary gland, somatostatin has attracted much attention because of its functional role in the regulation of a wide variety of physiological functions in the brain, pituitary, pancreas, gastrointestinal tract, adrenals, thyroid, kidney and immune system. In addition to its negative role in the control of endocrine and exocrine secretions, somatostatin and analogs also exert inhibitory effects on the proliferation and survival of normal and tumor cells. Over the past 15 years, studies have begun to reveal some of the molecular mechanisms underlying the antitumor activity of somatostatin. This review covers the present knowledge in the antitumor effect of somatostatin and analogs and discusses the perspectives of novel clinical strategies based on somatostatin receptor sst2 gene transfer therapy.
Endocrine pancreatic tumors (EPTs) in von Hippel-Lindau (VHL) disease pose difficult management problems. We aimed to assess (1) the accuracy of somatostatin receptor scintigraphy, (2) histological features with focus on malignancy and genotype-phenotype correlations, and (3) prognosis of VHL-EPT.
Thirty-five patients with EPT-VHL (20 women; median age, 37 years) from 29 families were studied. Histological diagnosis was available in 29 patients. Endocrine pancreatic tumor patients were treated surgically (n = 22), medically (n = 8), or followed (n = 5). Somatostatin receptor scintigraphy was performed in 27 patients. Germinal alterations of the VHL gene were determined.
Tumors were malignant in 58% of patients. Somatostatin receptor scintigraphy was positive in 60% of cases, and weak expression of the somatostatin receptor type 2A was found in 47% of tumors. In operated patients, there was no mortality or tumor relapse (median follow-up, 5 [1-10] years). Mortality rate due to EPT was 6%. Germinal mutations were mainly located in exons 3 and 1, and a specific mutation (P86S) was identified.
Most EPTs in VHL patients are somatostatin receptor scintigraphy-positive and malignant, without correlation with the VHL genotype. Surgical resection is often required, but prognosis of these EPTs seems to be fairly good.