Pacák, Karel

Abstract Carney's triad (CTr) is a non-hereditary condition, primarily seen in young women, characterized by gastrointestinal stromal tumors (GIST), extra-adrenal paragangliomas and pulmonary chondromas. Most CTr patients present with GIST and pulmonary chondroma (incomplete CTr). A marked decrease in the enzymatic activity of succinate dehydrogenase (SDH) has been detected in these tumors, but the presence or absence of SDH mutations in CTr is controversial. A related disease, known as Carney-Stratakis Syndrome (CSS), has no female predisposition and presents with extra-adrenal paragangliomas and GIST tumors, without pulmonary chondromas. In distinction to CTr, CSS is hereditary due to germline SDH mutations in the enzyme's subunits (SDHA, SDHB, SDHC and SDHD) with corresponding decreased SDH activity in associated tumors. We have investigated 64 patients with CTr for germline mutations and/or deletions in the SDH subunit genes; four patients were found to have germline mutations in SDHB or SDHC. All four patients had multifocal gastric GIST and pulmonary chondromas at diagnosis; two subsequently developed paragangliomas, confirmed by biopsy. One of the patients with CTr and a SDHB mutation had a nephew with the same mutation and a neuroblastoma, confirming a previously reported association of neuroblastoma with gist (JMG 2009; 46:215, and AJMG 2010; 152A: 1531). We conclude that few CTr patients maybe more correctly classified as having CSS; the genetic distinction of CTr from CSS needs further study. [S.A.B. and P.X. should be regarded as joint first authors.] Citation Format: Sosipatros A. Boikos, Paraskevi Xekouki, Fabio R. Faucz, Karel Pacak, Margarita Raygada, Karen Adams, Evan Szarek, Evan Ball, Su Young Kim, Elena Fumagalli, Lee J. Helman, J Aidan Carney, Constantine A. Stratakis. Few Carney's Triad patients have mutations in two subunits of the succinate dehydrogenase enzyme (SDHB, SDHC). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 568. doi:10.1158/1538-7445.AM2014-568

BACKGROUND Pheochromocytomas are rare catecholamine-producing tumors derived in more than 30% of cases from mutations in 9 tumor-susceptibility genes identified to date, including von Hippel-Lindau tumor suppressor (VHL); succinate dehydrogenase complex, subunit B, iron sulfur (Ip) (SDHB); and succinate dehydrogenase complex, subunit D, integral membrane protein (SDHD). Testing of multiple genes is often undertaken at considerable expense before a mutation is detected. This study assessed whether measurements of plasma metanephrine, normetanephrine, and methoxytyramine, the O-methylated metabolites of catecholamines, might help to distinguish different hereditary forms of the tumor. METHODS Plasma concentrations of O-methylated metabolites were measured by liquid chromatography with electrochemical detection in 173 patients with pheochromocytoma, including 38 with multiple endocrine neoplasia type 2 (MEN 2), 10 with neurofibromatosis type 1 (NF1), 66 with von Hippel-Lindau (VHL) syndrome, and 59 with mutations of SDHB or SDHD. RESULTS In contrast to patients with VHL, SDHB, and SDHD mutations, all patients with MEN 2 and NF1 presented with tumors characterized by increased plasma concentrations of metanephrine (indicating epinephrine production). VHL patients usually showed solitary increases in normetanephrine (indicating norepinephrine production), whereas additional or solitary increases in methoxytyramine (indicating dopamine production) characterized 70% of patients with SDHB and SDHD mutations. Patients with NF1 and MEN 2 could be discriminated from those with VHL, SDHB, and SDHD gene mutations in 99% of cases by the combination of normetanephrine and metanephrine. Measurements of plasma methoxytyramine discriminated patients with SDHB and SDHD mutations from those with VHL mutations in an additional 78% of cases. CONCLUSIONS The distinct patterns of plasma catecholamine O-methylated metabolites in patients with hereditary pheochromocytoma provide an easily used tool to guide cost-effective genotyping of underlying disease-causing mutations.

Background— Nearly half of patients with heart failure have a preserved ejection fraction (HFpEF). Symptoms of exercise intolerance and dyspnea are most often attributed to diastolic dysfunction; however, impaired systolic and/or arterial vasodilator reserve under stress could also play an important role. Methods and Results— Patients with HFpEF (n=17) and control subjects without heart failure (n=19) generally matched for age, gender, hypertension, diabetes mellitus, obesity, and the presence of left ventricular hypertrophy underwent maximal-effort upright cycle ergometry with radionuclide ventriculography to determine rest and exercise cardiovascular function. Resting cardiovascular function was similar between the 2 groups. Both had limited exercise capacity, but this was more profoundly reduced in HFpEF patients (exercise duration 180±71 versus 455±184 seconds; peak oxygen consumption 9.0±3.4 versus 14.4±3.4 mL · kg −1 · min −1 ; both P <0.001). At matched low-level workload, HFpEF subjects displayed ≈40% less of an increase in heart rate and cardiac output and less systemic vasodilation (all P <0.05) despite a similar rise in end-diastolic volume, stroke volume, and contractility. Heart rate recovery after exercise was also significantly delayed in HFpEF patients. Exercise capacity correlated with the change in cardiac output, heart rate, and vascular resistance but not end-diastolic volume or stroke volume. Lung blood volume and plasma norepinephrine levels rose similarly with exercise in both groups. Conclusions— HFpEF patients have reduced chronotropic, vasodilator, and cardiac output reserve during exercise compared with matched subjects with hypertensive cardiac hypertrophy. These limitations cannot be ascribed to diastolic abnormalities per se and may provide novel therapeutic targets for interventions to improve exercise capacity in this disorder.

Abstract Pheochromocytomas are rare catecholamine-producing neuroendocrine tumors that are usually benign, but which may also present as or develop into a malignancy. Predicting such behavior is notoriously difficult and there are currently no curative treatments for malignant tumors. This report follows from a workshop at the Banbury Conference Center, Cold Spring Harbor, New York, on the 16th–18th November 2003, held to review the state of science and to facilitate future progress in the diagnosis and treatment of malignant pheochromocytoma. The rarity of the tumor and the resulting fragmented nature of studies, typically involving small numbers of patients, represent limiting factors to the development of effective treatments and diagnostic or prognostic markers for malignant disease. Such development is being facilitated by the availability of new genomics-based tools, but for such approaches to succeed ultimately requires comprehensive clinical studies involving large numbers of patients, stringently collected clinical data and tumor samples, and interdisciplinary collaborations among multiple specialist centers. Nevertheless, the well-characterized hereditary basis and the unique functional nature of these neuroendocrine tumors provide a useful framework that offers advantages for establishing the pathways of tumorigenesis and malignancy. Such findings may have relevance for understanding the basis of other more common malignancies where similar frameworks are not available. As the relevant pathways leading to pheochromocytoma are established it should be possible to take advantage of the new generation of drugs being developed to target specific pathways in other malignancies. Again the success of this will require well-designed and coordinated multicenter studies.