Diagnosis, Localization, Pathophysiology, and Molecular Biology of Pheochromocytoma

Karel Pacak, MD, PhD, DSc, Head, Section on Medical Neuroendocrinology
Jie He, MD, Clinical Associate
Sebastian Havekes, MD, Volunteer
Karen T. Adams, MSc, CRNP, Research Nurse
Stephanie Fliedner, MS, Summer Student
Edwin W. Lai, BS, Predoctoral Fellow
Lucia Martiniova, MS, Predoctoral Fellow
Thanh-Truc Huynh, MS, Biologist
Kathryn King, BS, Postbaccalaureate Fellow

We conduct patient-oriented research into the etiology, pathophysiology, genetics, diagnosis, and treatment of pheochromocytoma (PHEO) and paraganglioma (PGL). Projects include not only translational research—applying basic science knowledge to clinical diagnosis, pathophysiology, and treatment—but also “reverse translation research” by which clinical findings lead to new concepts for pursuit by basic researchers in the laboratory. Our goals are to (1) establish new and improved methods and strategies for diagnosis and localization of PHEO and PGL; (2) explain the molecular basis for varying clinical presentations of PHEO and PGL and establish the pathways of tumorigenesis; (3) search for new molecular and genetic markers for diagnosis and treatment of malignant PHEO and PGL ; and (4) facilitate new and improved collaborations and interdisciplinary studies. To achieve these goals, we base our strategy on multidisciplinary collaborations with investigators from several NIH Institutes and outside medical centers. We link a patientoriented component with two bench-level components (Figure 10.1). The patient-oriented component (medical neuroendocrinology) is the driving force for our hypotheses and discoveries. The two bench-level components (tumor pathogenesis and chemistry; biomarkers) emphasize, first, technologies of basic research tailored for pathway and target discovery and, second, the development of discoveries into clinical applications.

Figure 10.1

Hereditary PHEOs and PGLs

Pacak, He, Adams, Lai; in collaboration with Timmers, Huynh, King, Chen, Reynolds, Ling, Fojo, Linehan, Libutti, Merino, Raygada, Morris, Munson, Lubensky, Wesley, Lenders, Widimsky, Eisenhofer, Tischler

Advances in genetics and the recognition of the high prevalence of PHEO/PGL in certain familial syndromes dictate mandatory tumor screening in patients with those syndromes, irrespective of the presence of classical clinical signs and symptoms. Accumulating data also indicate that many more PHEOs/PGLs result from germline mutations than previously recognized, raising the importance of considering an underlying hereditary condition even in those patients without an obvious family history. To date, mutations in five main genes have been identified as responsible for familial PHEOs/PGLs (Table 10.1): (1) the von Hippel-Lindau (VHL) gene in VHL syndrome; (2) the RET gene in multiple endocrine neoplasia type 2 (MEN 2); (3) the neurofibromatosis type 1 (NF-1) gene associated with von Recklinghausen’s disease; and (4) mutations in genes encoding mainly the B and D subunits of mitochondrial succinate dehydrogenase (SDHB and SDHD) associated with familial PHEOs/PGLs.

Table 10.1: Hereditary PHEO/PGL: Facts and Figures

Gene	VHL	RET	NF1	SDHD	SDHB
Chromosome	3p25-26	10q11.2	17q11.2	11q23	1p36.13
Exons	3	21	59	8	4
Frequency in "sporadic" tomors (%)	2-11	1-5	unknown	3-10	4-7
Predisposition to malignancy (%)	~3	<3	11	<2	66-83
Tumor catecholamine phenotype	NE	EPI	EPI	unknown	NE/DA
Adrenal disease	++	++	++	+	+
Extra-adrenal disease	+	rare	+	++	++

Low (+) to high (++) frequency; NE: norepinephrine; EPI: epinephrine; DA: dopamine

Patients with mutations of SDHB and SDHD genes are more likely to develop extra-adrenal rather than adrenal tumors. Furthermore, SDHB mutations appear to be associated with more aggressive tumor behavior and a higher rate of malignancy than are SDHD mutations. In an initial study, we examined the frequency of SDHB mutations in patients with malignant PHEOs/PGLs and found pathogenic SDHB mutations in 30 percent of such patients. In patients presenting initially with primary abdominal PGLs, mutations of the SDHB gene were associated with about one-half of all malignancies. The high frequency of SDHB germline mutations among patients with malignant disease, particularly when originating from PGL, justifies a high priority for SDHB germline mutation testing in these patients. Recently, however, malignant PGLs were also reported among a small minority of Dutch carriers of the SDHD founder mutation D92Y. Therefore, we investigated which SDHD mutations are associated with malignant PGL and found that germline SDHD mutations underlying metastatic PGL include G148D, Y114X, L85X, W43X, D92Y, and IVS2+5 G→A.

We also performed a retrospective analysis of 71 subjects with metastatic PHEO/PGL (30 subjects with SDHB mutation and 41 subjects without SDHB mutation), including three subjects with mutation of the RET gene, three subjects with mutation of the VHL gene, and one subject with mutation of the SDHD gene. Sixty-nine percent presented with bone metastases (77 percent of those with SDHB mutation and 63 percent of those without SDHB mutation), 39 percent with liver metastases, and 32 percent with lung metastases. The most common sites of bone involvement were thoracic spine (80 percent), lumbar spine (78 percent), and pelvic and sacral bones (78 percent). Subjects with SDHB mutation showed significantly higher involvement of long bones and pelvic and sacral bones than those without the mutation.

Pacak K, Eisenhofer G. An assessment of biochemical tests for the diagnosis of pheochromocytoma. Nat Clin Pract Endocrinol Metab 2007;3:744-745.
Passini B, McWhinney S, Bei T, Matyakhina L, Stergiopoulos S, Muchow M, Boikos S, Ferrando B, Pacak K, Guillaume A, Baudin E, Chompret A, Ellison JW, Briere J-J, Rustin P, Gimenez-Roqueplo A-P, Eng C, Carney JA, Stratakis CA. Clinical and molecular genetics of patients with the Carney-Stratakis syndrome and germline mutations of the genes coding for the succinate dehydrogenase subunits SDHB, SDHC, and SDHD. Eur J Human Genetics 2008;16:79-88.
Timmers HJ, Kozupa A, Eisenhofer G, Raygada M, Adams KT, Solis D, Lenders JW, Pacak K. Clinical presentations, biochemical phenotypes, and genotype-phenotype correlations in patients with SDHBassociated pheochromocytomas and paragangliomas. J Clin Endocrinol Metab 2007;92:779-786.
Timmers HJ, Pacak K, Bertherat J, Lenders JW, Eisenhofer G, Stratakis CA , Nicoli-Sire P, Huy PT, Burnichon N, Gimenez-Raqueplo AP. Mutation associated with succinate dehydrogenase d-related malignant pheochromocytoma. Clin Endocrinol 2008;64:561-566.

Imaging of various PHEOs and PGLs

Pacak, He, Havekes, Adams; in collaboration with Timmers, Chen, Reynolds, Ling, Fojo, Linehan, Morris, Wesley, Carrasquillo, Lenders, Ilias, Widimsky, Eisenhofer

We compared different imaging methods in various PHEOs/PGLs. Of 11 non-metastatic lesions detected by any technique, we detected eight lesions by ¹⁸F-DOPA PET, seven by ¹⁸F-FDA PET/CT, 8 by ¹⁸F-FDG PET/CT, and nine by ¹²³I-MIBG scintigraphy. Computed tomography (CT) and/or magnetic resonance imaging (MRI) identified 108 lesions in 19 patients with metastatic PGL. Functional imaging identified 80 additional lesions. Discrepant readings between the two nuclearmedicine physicians were solved by consensus for seven lesions on ¹⁸F-DOPA PET and seven lesions on ¹⁸F-FDA PET. Of 188 metastatic lesions, we detected 116 by ¹⁸F-DOPA PET, 110 by ¹⁸F-FDA PET/CT, 107 by ¹⁸F-FDG PET/CT, and 67 by ¹²³I-MIBG scintigraphy. In reference to lesions detected by CT and/or MRI, sensitivities were 52 percent for ¹⁸F-DOPA PET, 64 percent for ¹⁸F-FDA PET/CT, 72 percent for ¹⁸F-FDG PET/CT, and 54 percent for ¹²³I-MIBG scintigraphy. Sensitivities in reference to the total number of lesions detected by any technique were 62 percent for ¹⁸F-DOPA PET, 59 percent for ¹⁸F-FDA PET/CT, 57 percent for ¹⁸F-FDG PET/CT, and 36 percent for ¹²³I-MIBG scintigraphy.

The best overall sensitivity in detecting bone metastases was ¹⁸F-FDA PET (90 percent), followed by bone scintigraphy (82 percent), CT/MRI (78 percent), and ^123/131I-MIBG scintigraphy (71 percent). In subjects with SDHB mutation, imaging modalities with the best sensitivities for detecting bone metastases were CT/MRI (96 percent), bone scintigraphy (95 percent), and ¹⁸F-FDG PET (92 percent). In subjects without SDHB mutation, the modality with the best sensitivity for detecting bone metastases was ¹⁸F-FDA PET (100 percent). We concluded that bone scintigraphy should be used in the staging of patients with malignant PHEO/PGL, particularly in those with SDHB mutation. We highly recommend ¹⁸F-FDG PET as a PET imaging modality in SDHB mutation patients but ¹⁸F-FDA PET in patients without the mutation.

In another study, we investigated whether carbidopa also improves ¹⁸F-DOPA PET imaging of adrenal PHEOs. Two patients with non-metastatic adrenal PHEO and nine patients with extra-adrenal abdominal PGL (one non-metastatic, eight metastatic) underwent whole-body CT, MRI, baseline ¹⁸F-DOPA PET, and ¹⁸F-DOPA PET with oral pre-administration of carbidopa. We recorded the dynamics of tracer uptake by the lesions and the physiological distribution of ¹⁸F-DOPA in normal tissues. Seventy-eight lesions were detected by CT and/or MRI, 54 by baseline ¹⁸F-DOPA PET, and 57 by ¹⁸F-DOPA PET plus carbidopa. In reference to findings on CT and MRI, the sensitivities of baseline ¹⁸F-DOPA PET were 47.4 percent for lesions and 55.6 percent for positive body regions versus 50.0 percent (lesions) and 66.7 percent (regions) for ¹⁸F-DOPA PET plus carbidopa (both non-specific versus baseline). Compared with baseline, carbidopa resulted in the detection of additional lesions in 3 of 11 patients. Carbidopa increased the mean ±SD peak standard uptake value in index tumor lesions from 6.4±3.9 to 9.1±5.6. Carbidopa blocked the pancreas’s physiological uptake of ¹⁸F-DOPA, perhaps masking adrenal PHEO. We concluded that carbidopa enhances the sensitivity of ¹⁸F-DOPA PET for adrenal PHEOs and extra-adrenal abdominal PGLs by increasing the tumor-to-background ratio of tracer uptake. The sensitivity of ¹⁸F-DOPA PET for metastases of PGL appears to be limited.

We also evaluated seven VHL patients with adrenal PHEO confirmed by histopathology. We localized the adrenal PHEOs by using CT, MRI, [^123/131I]-MIBG scintigraphy, and [¹⁸F]-DA PET. [¹⁸F]-DA PET and CT localized the PHEOs in all seven patients. In contrast, three out of the seven patients had negative results with [^123/131I]-MIBG scintigraphy, and one out of six patients had negative MRI results. We found that [¹⁸F]-DA PET gives more promising results than [^123/131I]-MIBG scintigraphy in the diagnostic localization of VHL-related adrenal PHEO, with a 100 percent rate of localization. Thus, [¹⁸F]-DA PET in conjunction with CT/MRI should be considered an effective method for the proper localization of VHL-related adrenal PHEO.

Ilias I, Sahdev A, Reznek RH, Grossman AB, Pacak K. The optimal imaging of adrenal tumours: a comparison of different methods. Endocr Relat Cancer 2007;14:587-599.
Kaji P, Carrasquillo JA, Linehan WM, Chen CC, Eisenhofer G, Pinto PA, Lai EW, Pacak K. The role of 6-¹⁸F-fluorodopamine positron emission tomography in the localization of adrenal pheochromocytoma associated with von Hippel-Lindau syndrome. Eur J Endocrinol 2007;156:483-487.
Timmers HJLM , Hadi M, Carrasquillo JA, Chen CC , Martiniova L, Whatley M, Ling A, Eisenhofer G, Adams KT, Pacak K. The effects of carbidopa on the uptake of 6-¹⁸F-fluoro-L-DOPA in positron emission tomography of pheochromocytoma and extra-adrenal abdominal paraganglioma. J Nucl Med 2007;48:1599-1606.
Timmers HJLM , Kozupa A, Chen CC , Carrasquillo JA, Ling A, Eisenhofer G, Adams KT, Solis D, Lenders JWM, Pacak K. Superiority of fluorodeoxyglucose positron emission tomography to other functional imaging techniques in the evaluation of metastatic SDHB-associated pheochromocytoma and paraganglioma. J Clin Oncol 2007;25:2262-2269.
Zelinka T, Timmers HJM, Kozupa A, Chen CC , Carrasquillo JA, Reynolds JC, Ling A, Eisenhofer G, Lazurova I, Adams KT, Whatley MA, Widimsky J Jr., Pacak K. Role of positron emission tomography and bone scintigraphy in the evaluation of bone involvement in metastatic pheochromocytoma and paraganglioma: specific implications for succinate dehydrogenase enzyme subunit B gene mutations. Endocr Relat Cancer 2008;15:311-323.

Other findings

Pacak, He, Adams; in collaboration with Fojo, Chen, Reynolds, Carrasquillo, Wesley, Puri, Lubensky, Zhuang, Morris, Merino, Eisenhofer, Lenders, Tischler, Widimsky

Patients who undergo successful surgery for apparently benign PHEO/PGL have a lower life expectancy than the general population because patients may still develop metastatic disease during post-surgical follow-up. Hypertension persisted in two-thirds of recurrence-free patients. Life-long follow-up is therefore warranted in benign PHEO/PGL surgery patients.

In a non-randomized, single-arm trial, we conducted a long-term follow-up of 18 patients with a diagnosis of PHEO/PGL who were treated with a combination of cyclophosphamide, vincristine, and dacarbazine (CVD chemotherapy). We found that combination chemotherapy with CVD produced objective tumor responses in patients with advanced malignant PHEO/PGL, but we observed no difference in overall survival between patients whose tumors objectively shrank and those with stable or progressive disease. However, patients reported improvement in symptoms, exhibited objective improvements in blood pressure, and evidenced tumor shrinkage that made surgical resection possible. We concluded that CVD therapy was not indicated in every patient with metastatic PHEO/PGL; nevertheless, such therapy should be considered in the management of patients with symptoms and when tumor shrinkage might be beneficial.

In collaboration with other medical centers, we found that catecholamine excess in PHEO was accompanied by an increase in carotid-femoral pulse-wave velocity, which was reversed by successful tumor removal. Age, mean blood pressure, and norepinephrine levels were independent predictors of pulse-wave velocity in patients with PHEO.

Through our initial microarray profiling data, we detected a high expression of IL13Rα2 mRNA in various PHEOs, indicating that IL13Rα2 could be a potential target for treatment of metastatic PHEO. Therefore, we initiated a collaboration with Raj Puri to study the expression of IL13Rα2 by various mouse pheochromocytoma (MPC) cells and PHEOs. If we detected such expression, we would investigate the utility of IL13Rα2-Pseudomonas exotoxin fusion protein (IL13-PE38) in mice. IL13-PE38 binds to IL13Rα2 and kills cells that carry it. Our initial results, based on RTPCR, confirmed the presence of IL13Rα2 on human PHEO cells. Thus, we plan to begin preclinical studies on our mouse model to evaluate the therapeutic potential of IL13-PE38. If successful, the therapy may offer a treatment option for IL13Rα2-positive metastatic PHEO patients.

Click for a larger version.
Figure 10.2

We hypothesized that the differences in catecholamine release between VHL- and MEN 2–related PHEO s may reflect the presence of different pathways of catecholamine secretion, namely, regulated versus constitutive pathways. Our initial microarray and proteomic databases indicate under expression of numerous components of the regulated secretory pathway in VHL compared with MEN 2 tumors (e.g., SNAP25, syntaxin, rabphilin 3A, calcium-dependent secretion activator, syntaphilin, chromogranin A and B, secretogranin II, and neuropeptide Y). Many of these components are downregulated by the transcriptional repressor REST (RE1-silencing transcription factor) and/or have genes with REST binding sites in regulatory regions. Using QRT-PC R, we confirmed our microarray evidence of higher expression of REST in VHL than in MEN 2 tumors. We found that overexpression of REST in PC12 cells reduces catecholamine stores, the number of secretory vesicles, and the expression of chromogranins and increases baseline catecholamine secretion while inhibiting calcium-dependent secretion. These findings are congruent with our data—already published or in press—comparing VHL with MEN 2 tumors. The constitutive secretory pathway (shown in Figure 10.2) is spontaneous, rapid, and not responsive to secretagogues. Secretion by the regulated pathways is calcium-dependent. The pathways consist of vesicles that sort peptides and pack proteins—both processes being dependent on a V-ATP ase-mediated proton gradient and under the control of REST.

Brouwers MF, Glasker S, Nave AF, Vogel T, Vortmeyer AO , Lubensky I, Huang S, Abu-Asab MS, Eisenhofer G, Weil RJ, Park DM, Linehan M, Pacak K, Zhuang Z. Proteomic profiling of VHL and MEN2 pheochromocytomas reveals different expression of chromogranin B. Endocr Relat Cancer 2007;14:463-471.
Cleary S, Phillips JK, Huynh TT, Pacak K, Elkahloun AG, Barb J, Worrell RA, Goldstein DS, Eisenhofer G. Neuropeptide Y expression in pheochromocytomas: relative absence in tumors from patients with von Hippel-Lindau syndrome. J Endocrinol 2007;193:225-233.
Cleary S, Phillips JK, Huynh T-T, Pacak K, Fliedner S, Elkahloun AG, Munson P, Worrell RA, Eisenhofer G. Chromogranin A expression in phaeochromocytomas associated with von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2. Horm Metab Res 2008;39:876-883.
Eisenhofer G, Huynh T-T, Elkahloun A, Morris JC, Bratslavsky G, Linehan MW, Zhuang Z, Balgley MB, Lee CS , Mannelli M, Lenders JWM, Bornstein R, Pacak K. Differential expression of the regulated catecholamine secretory pathway in different hereditary forms of pheochromocytoma. Am J Physiol Endocrinol Metab 2008;295:E1223-E1233.
Huang H, Abraham J, Hung E, Averbuch S, Merino M, Steinberg S, Pacak K, Fojo T. Treatment of malignant pheochromocytoma/paraganglioma with cyclophosphamide, vincristine and dacarbazine (CVD): recommendation from a twenty-two year follow up of eighteen patients. Cancer Res 2008;113:2020-2028.

An animal model of PHEO and cell culture studies

Pacak, Martiniova, Lai, Tischler, Puri, Morris, Merino, Green, Chan, Albanase, Fliedner, Porter, Elkahloun

The use of suitable laboratory animal models enhances the speed with which new treatments for PHEO /PGL may be evaluated, particularly in the case of uncommon malignancies that are typically not the subject of clinical trials. Previously, we reported a new mouse model of metastatic PHEO based on a tail vein injection of a MPC line that reproducibly generated several liver tumors in mice. Recently, we found that microCT and MRI were approximately equal in their ability to detect hepatic metastases at a size threshold of 350 mm. In the lungs, MRI was more sensitive than microCT, detecting lesions 0.6 mm in diameter versus 1 mm for microCT. In addition, MRI was more sensitive than microCT to lesions in the kidneys, bone, ovaries, and adrenal glands. MRI demonstrated higher contrast-to-noise ratio than microCT. We concluded that, in addition to the advantage of not exposing an animal to ionizing radiation, MRI rather than microCT provided a more complete assessment of the extent of metastases in our mouse model.

In another study, we enhanced the animal model by modifying the number of injected cells, the length of trypsin treatment, and the temperature for cell storage before injection; we enhanced tumor growth by removing metastatic lesions, subjecting them to serial passage, and re-selecting metastases. We evaluated the effect of these modifications on tumor growth by using in vivo MRI. The results showed that the number of injected cells, the temperature for cell storage before injection, and the length of trypsin treatment are important factors in producing faster-growing, more aggressive tumors that yield secondary metastatic lesions at other sites. Serial culture and selection of metastatic liver lesions produced even more aggressive PHEO cells that retained their biochemical phenotype. Microarray comparison of the more aggressive cells with the parental cell line identified genes important for the cells’ rapid metastatic process.

ErbB-2/Her2/Neu is a growth factor receptor tyrosine kinase frequently overexpressed in tumors; clinical evidence suggests that enhanced ErbB-2 growth factor receptor signaling may play a role in PHEO. An ongoing study showed that ectopic expression of an activated ErbB-2 transgene resulted in bilateral adrenal PHEO. Analyses of tumor samples and normal adrenal tissue revealed a great reduction in the levels of the Pten tumor suppressor protein in PHEOs while levels of the cell cycle–regulatory protein cyclin D1 usually increased. In addition, levels of phospo-AKT were higher in PHEOs than in normal adrenal tissue. Biochemical analyses established that PHEOs were functionally active, producing abundant levels of the catecholamines epinephrine and norepinephrine. These data establish that increased ErbB-2 growth factor receptor signaling in the adrenal medulla can lead to PHEO through combined influences on Pten, AKT, and cyclin D1.

Recombinant adenoviruses (rAd) have found wide application as gene transfer vectors in both the laboratory and human clinical trials. We are investigating the effects of adenoviral-mediated gene transfer in primary bovine adrenal chromaffin cells (BACC) and an MPC line. We infected cells with one of three non-replicating E1/E3-deleted (E1^–/E3^–) rAd vectors: Ad.GFP, which expresses a green fluorescent protein; Ad.null, which expresses no transgene; or Ad.C2.TK, which expresses the herpes simplex virus-1 thymidine kinase gene (TK). Forty-eight hours after exposure to Ad.GFP, the percentage of GFP-expressing BACCs ranged from 23.5 to 97 percent in a dose-dependent manner and similarly from 1.06 to 84.4 percent in the MPC, indicating that adrenomedullary cells are a potentially valuable target for adenoviral-mediated gene transfer. Ultrastructural analysis, however, revealed profound changes in the nucleus and mitochondria of cells infected with rAd. Furthermore, infection of BACCs with Ad.null was accompanied by a time- and dose-dependent decline in cell survival due solely to the vector. Specific whole-cell norepinephrine uptake also rose in a time- and dose-dependent manner in BACCs. Infection of MPC cells with the Ad.C2.TK vector sensitized them to the cytotoxic effect of the antiviral drug ganciclovir in direct proportion to the fraction of cells infected with the virus. We conclude that rAd may alter the structural and functional integrity of adrenomedullary cells, potentially interfering with the normal stress response. At the same time, given the vector’s ability to deliver and express genes effectively in PHEO cells, it may be useful in the gene therapy of adrenomedullary tumors.

Alesci S, Perera SN, Lai EW, Kukura C, Abu-Asab M, Tsokos M, Morris JC, Pacak K. Adenoviral gene transfer in bovine adrenomedullary and murine pheochromocytoma cells: potential clinical and therapeutic relevance. Endocrinology 2007;148:3900-3907.
Lai EW, Rodriguez O, Aventian M, Cromelin C, Fricke S, Martiniova L, Lubensky IA, Lisanti M, Picard KL, Powers JF, Tischler AS , Pacak K, Albanese C. Erb-2 induces bilateral adrenal pheochromocytoma formation in mice. Cell Cycle 2007;6:1946-1950.
Ohta S, Lai EW, Morris JC, Pang AL Y, Watanabe M, Yazawa H, Zhang R, Green JE, Chan W-Y, Sirajuddin P, Taniguchi S, Powers JF, Tischler AS, Pacak K. Metastasis-associated gene expression profile of liver and subcutaneous lesions derived from mouse pheochromocytoma cells. Mol Carcinog 2008;47:245-251.

Collaborators

Mones Abu-Asab, PhD, Pathology Department, Clinical Center, NIH, Bethesda, MD
Chris Albanese, PhD, Georgetown University, Washington, DC
Jorge A. Carrasquillo, MD, Memorial Sloan-Kettering Cancer Center, New York, NY
Wai-Yee Chan, PhD, Program in Reproductive and Adult Endocrinology, NICHD, Bethesda, MD
Clara C. Chen, MD, Nuclear Medicine Department, Clinical Center, NIH, Bethesda, MD
Graeme Eisenhofer, PhD, Universität Dresden, Dresden, Germany
Abdel G. Elkahloun, PhD, Genome Technology Branch, NHGRI, NIH, Bethesda, MD
Tito Fojo, MD, PhD, Medical Oncology Branch, NCI, Bethesda, MD
G&B Solutions, Inc., McLean, VA
Jeff Green, MD, PhD, Laboratory of Cancer Biology and Genetics, NCI, Bethesda, MD
Ioannis Ilias, MD, University of Patras, Patras, Greece
Jacques W.M. Lenders, MD, St. Radboud University, Nijmegen, The Netherlands
Steven K. Libutti, MD, Surgery Branch, NCI, Bethesda, MD
W. Marston Linehan, MD, Urologic Oncology Branch, NCI, Bethesda, MD
Alexander Ling, MD, Radiology Department, Clinical Center, NIH, Bethesda, MD
Irina A. Lubensky, MD, Cancer Diagnosis Program, NCI, Bethesda, MD
Maria J. Merino, MD, Pathology Department, NCI, Bethesda, MD
Molecular Insight Pharmaceuticals, Inc., Cambridge, MA
John C. Morris, MD, PhD, Metabolism Branch, NCI, Bethesda, MD
Peter J. Munson, PhD, Center for Information Technology, NIH, Bethesda, MD
Alan L.Y. Pang, MD, PhD, Program in Reproductive and Adult Endocrinology, NICHD, Bethesda, MD
Forbes D. Porter, MD, PhD, Program in Developmental Endocrinology and Genetics, NICHD, Bethesda, MD
Raj K. Puri, MD, PhD, Center for Biologics Evaluation and Research, FDA, Rockville, MD
Margarita Raygada, PhD, Program in Reproductive and Adult Endocrinology, NICHD, Bethesda, MD
James C. Reynolds, MD, Nuclear Medicine Department, Clinical Center, NIH, Bethesda, MD
David Thomasson, PhD, Radiology Department, Clinical Center, NIH, Bethesda, MD
Henri Timmers, MD, PhD, St. Radboud University, Nijmegen, The Netherlands
Arthur S. Tischler, MD, PhD, New England Medical Center, Boston, MA
Robert A. Wesley, PhD, Clinical Center, NIH, Bethesda, MD
Jiri Widimsky, MD, PhD, Charles University, Prague, Czech Republic
Zhengping Zhuang, MD, PhD, Surgical Neurology Branch, NINDS, NIH, Bethesda, MD

For further information, contact karel@mail.nih.gov.