Pheochromocytoma is a tumor of the chromaffin cells in the adrenal medulla and sympathetic paraganglia, which synthesizes and secretes catecholamines. Norepinephrine, epinephrine, and dopamine all ...act on their target receptors, which causes a physiologic change in the body. High circulating levels of catecholamines can lead to severe hypertension and can have devastating effects on multiple body systems (eg, cardiovascular, cerebrovascular), and can lead to death if untreated. Although surgical treatment represents the only modality of ultimate cure, pharmacologic preoperative treatment remains the mainstay of successful outcome.
The use of ivabradine, an
I
f
current inhibitor, to manage tachycardia and heart failure due to massive catecholamine release in a patient with a metastatic paraganglioma and β-adrenoceptor ...desensitization is reported.
A woman with a genetic predisposition to pheochromocytoma was receiving venlafaxine, which can increase plasma metanephrine levels. Before blood is drawn to determine metanephrine and catecholamine ...levels, medications that might interfere with results should be discontinued.
To the Editor:
A 51-year-old woman presented to our clinic in April 2010 with a 10-year history of hypertension and anxiety. The patient was concerned about pheochromocytoma because her identical twin sister had died at the age of 50 from metastatic pheochromocytoma. Her nephew and two grandsons were known to have mutations in the gene for succinate dehydrogenase subunit B (
SDHB
), which increases the risk of pheochromocytoma and paraganglioma.
1
Genetic analysis confirmed that she carried an
SDHB
mutation and therefore required careful follow-up evaluation. Her plasma normetanephrine level was 651 pg per milliliter (reference range, 0 to 145) . . .
Neuroendocrine tumors overexpress somatostatin receptors, which serve as important and unique therapeutic targets for well-differentiated advanced disease. This overexpression is a well-established ...finding in gastroenteropancreatic neuroendocrine tumors which has guided new medical therapies in the administration of somatostatin analogs, both "cold", particularly octreotide and lanreotide, and "hot" analogs, chelated to radiolabeled isotopes. The binding of these analogs to somatostatin receptors effectively suppresses excess hormone secretion and tumor cell proliferation, leading to stabilization, and in some cases, tumor shrinkage. Radioisotope-labeled somatostatin analogs are utilized for both tumor localization and peptide radionuclide therapy, with
Ga-DOTATATE and
Lu-DOTATATE respectively. Benign and malignant pheochromocytomas and paragangliomas also overexpress somatostatin receptors, irrespective of embryological origin. The pattern of somatostatin receptor overexpression is more prominent in
gene mutation, which is more aggressive than other subgroups of this disease. While the Food and Drug Administration has approved the use of
Ga-DOTATATE as a radiopharmaceutical for somatostatin receptor imaging, the use of its radiotherapeutic counterpart still needs approval beyond gastroenteropancreatic neuroendocrine tumors. Thus, patients with pheochromocytoma and paraganglioma, especially those with inoperable or metastatic diseases, depend on the clinical trials of somatostatin analogs. The review summarizes the advances in the utilization of somatostatin receptor for diagnostic and therapeutic approaches in the neuroendocrine tumor subset of pheochromocytoma and paraganglioma; we hope to provide a positive perspective in using these receptors as targets for treatment in this rare condition.
Pheochromocytoma and paraganglioma (PCPGs) are rare neuroendocrine tumors that arise from the chromaffin tissue of adrenal medulla and sympathetic ganglia. Although metastatic PCPGs account for only ...10% of clinical cases, morbidity and mortality are high because of the uncontrollable mass effect and catecholamine level generated by these tumors. Despite our expanding knowledge of PCPG genetics, the clinical options to effectively suppress PCPG progression remain limited. Several recent translational studies revealed that PCPGs with different molecular subtypes exhibit distinctive oncogenic pathways and spectrum of therapy resistance. This suggests that therapeutics can be adjusted based on the signature molecular and metabolic pathways of PCPGs. In this review, we summarized the latest findings on PCPG genetics, novel therapeutic targets, and perspectives for future personalized medicine.
Cluster I pheochromocytomas and paragangliomas (PCPGs) tend to develop malignant transformation, tumor recurrence, and multiplicity. Transcriptomic profiling suggests that cluster I PCPGs and other ...related tumors exhibit distinctive changes in the tricarboxylic acid (TCA) cycle, the hypoxia signaling pathway, mitochondrial electron transport chain, and methylation status, suggesting that therapeutic regimen might be optimized by targeting these signature molecular pathways.
In the present study, we investigated the molecular signatures in clinical specimens from cluster I PCPGs in comparison with cluster II PCPGs that are related to kinase signaling and often present as benign tumors.
We found that cluster I PCPGs develop a dependency to mitochondrial complex I, evidenced by the upregulation of complex I components and enhanced NADH dehydrogenation. Alteration in mitochondrial function resulted in strengthened NAD
metabolism, here considered as a key mechanism of chemoresistance, particularly, of succinate dehydrogenase subunit B (
)-mutated cluster I PCPGs via the PARP1/BER DNA repair pathway. Combining a PARP inhibitor with temozolomide, a conventional chemotherapeutic agent, not only improved cytotoxicity but also reduced metastatic lesions, with prolonged overall survival of mice with
knockdown PCPG allograft.
In summary, our findings provide novel insights into an effective strategy for targeting cluster I PCPGs, especially those with
mutations.
.
Abstract
Context:
Pheochromocytomas and paragangliomas (PPGLs) in children are often hereditary and may present with different characteristics compared with adults. Hereditary PPGLs can be separated ...into cluster 1 and cluster 2 tumors due to mutations impacting hypoxia and kinase receptor signaling pathways, respectively.
Objective:
To identify differences in presentation of PPGLs between children and adults.
Design:
A retrospective cross-sectional clinical study.
Setting:
Seven tertiary medical centers.
Patients:
The study included 748 patients with PPGLs, including 95 with a first presentation during childhood. Genetic testing was available in 611 patients. Other data included locations of primary tumors, presence of recurrent or metastatic disease, and plasma concentrations of metanephrines and 3-methoxytyramine.
Results:
Children showed higher (P < 0.0001) prevalence than adults of hereditary (80.4% vs 52.6%), extra-adrenal (66.3% vs 35.1%), multifocal (32.6% vs 13.5%), metastatic (49.5% vs 29.1%), and recurrent (29.5% vs 14.2%) PPGLs. Tumors due to cluster 1 mutations were more prevalent among children than adults (76.1% vs 39.3%; P < 0.0001), and this paralleled a higher prevalence of noradrenergic tumors, characterized by relative lack of increased plasma metanephrine, in children than in adults (93.2% vs 57.3%; P < 0.0001).
Conclusions:
The higher prevalence of hereditary, extra-adrenal, multifocal, and metastatic PPGLs in children than adults represents interrelated features that, in part, reflect the lower age of disease presentation of noradrenergic cluster 1 than adrenergic cluster 2 tumors. The differences in disease presentation are important to consider in children at risk for PPGLs due to a known mutation or previous history of tumor.
This study establishes the link between extraadrenal, multifocal, metastatic, reccurent, hereditary PPGLs to a higher prevalence of noradrenergic and cluster 1 tumors in pediatric than adults.
Whereas benign pheochromocytomas and paragangliomas are often successfully cured by surgical resection, treatment of metastatic disease can be challenging in terms of both disease control and symptom ...control. Fortunately, several options are available, including chemotherapy, radiation therapy, and surgical debulking. Radiolabeled metaiodobenzylguanidine (MIBG) and somatostatin receptor imaging have laid the groundwork for use of these radiopharmaceuticals as theranostic agents.
I-MIBG therapy of neuroendocrine tumors has a long history, and the recent approval of high-specific-activity
I-MIBG for metastatic or inoperable pheochromocytoma or paraganglioma by the U.S. Food and Drug Administration has resulted in general availability of, and renewed interest in, this treatment. Although reports of peptide receptor radionuclide therapy of pheochromocytoma and paraganglioma with
Y- or
Lu-DOTA conjugated somatostatin analogs have appeared in the literature, the approval of
Lu-DOTATATE in the United States and Europe, together with National Comprehensive Cancer Network guidelines suggesting its use in patients with metastatic or inoperable pheochromocytoma and paraganglioma, has resulted in renewed interest. These agents have shown evidence of efficacy as palliative treatments in patients with metastatic or inoperable pheochromocytoma or paraganglioma. In this continuing medical education article, we discuss the therapy of pheochromocytoma and paraganglioma with
I-MIBG and
Y- or
Lu-DOTA-somatostatin analogs.
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