Functional paraganglioma with tumor thrombus in the inferior vena cava, first case report

Pheochromocytoma (PHEO) is a rare neuroendocrine that tumor originated from the adrenal medulla that secrets catecholamines. Tumors from extra-adrenal chromaffin tissues are called extra-adrenal PHEO or paraganglioma (PGL). To our knowledge, adrenal PHEO and subclinical PGL with inferior vena cava (IVC) invasion had been sporadically reported, while functional PGL with IVC tumor thrombus has not been publicly reported yet. Perioperative management of those diseases is less well established because of their multidisciplinary nature and rarity. We herein present a case of primary malignant PGL with IVC invasion. A 16-year-old female patient with a history of severe paroxysmal hypertension was admitted to Peking Union Medical College Hospital on suspicion of retroperitoneal mass. In-house diagnostic work-up revealed a malignant PGL with IVC invasion, inferior mesenteric artery encasement and, aorta engagement. Multi-disciplinary discussions were held and careful preoperative preparation plans were made. After everything was ready, the functional PGL and tumor thrombus were completely resected, then a reconstruction of IVC was performed. The patient was discharged on postoperative day 14 and all her clinical symptoms disappeared afterward. No evidence of tumor residual or metastasis was found in the subsequent six months of follow-up. Gene tests were made for her and her family. Albeit its rarity, functional PGL with IVC invasion is not unresectable, a multi-disciplinary task force should be established to settle down every detail. We recommended 3-dimensional imaging reconstruction for gaining a better anatomic understanding. Literature reviews showed that complete resection is the premise of a good prognosis. In particular cases, complementary or alternative therapy like chemotherapy and ¹³¹I-metaiodobenzylguanidine might help, family hereditary genetic tests are advised as well.

131I-MIBG negative progressive symptomatic metastatic paraganglioma: response and outcome with 177Lu-DOTATATE peptide receptor radionuclide therapy

OBJECTIVE

The primary aim of this study was to evaluate the long-term outcome of ¹⁷⁷Lu-DOTATATE PRRT in terms of clinical, biochemical and imaging response rates, disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) in ¹³¹I-metaiodobenzylguanidine (MIBG) negative progressive/symptomatic locally advanced or metastatic paragangliomas (PGL). The secondary aims of this study were to determine clinical toxicity of ¹⁷⁷Lu-DOTATATE and association of PFS with various variables.

MATERIALS AND METHODS

¹³¹I-MIBG negative PGL with progressive/symptomatic locally advanced or metastatic disease that underwent ¹⁷⁷Lu-DOTATATE PRRT from 2012 to 2019 in our institute were evaluated. Standard dose activity of 5.55-7.4 GBq per cycle of ¹⁷⁷Lu-DOTATATE was administered in somatostatin receptor (SSTR) positive PGL. Post-PRRT response was evaluated under three broad categories: (a) symptomatic, (b) biochemical, and (c) imaging (molecular and anatomic imaging). The PFS and OS since first ¹⁷⁷Lu-DOTATATE cycle were determined. Associations of PFS with various variables were also investigated. The clinical toxicities of ¹⁷⁷Lu-DOTATATE in PGL were determined.

RESULTS

Amongst a total of 9 PGL patients, response to ¹⁷⁷Lu-DOTATATE was seen in six patients, two patients, four patients and three patients on symptomatic, biochemical, molecular and anatomical based imaging response evaluation categories respectively with DCR of 67%. The median PFS and OS were not reached at a median follow-up of 40 months. Estimated PFS rate of 63% (95% CI 30-96%) and OS rate of 65% (95% CI 32-97%) were noticed at 40 months. Significant association of PFS was found for site of PGL (non-HNPGL), total cumulative dose of PRRT (> 22.2 GBq), and number of PRRT cycles patient received (≥ 4cycles). ¹⁷⁷Lu-DOTATATE was well tolerated without acute catecholamine crisis, nephrotoxicity or bone marrow suppression of any grade or high-grade (grade ≥ 2) hematological toxicities.

CONCLUSION

Our study showed favorable results with minimal low-grade and easily manageable side effects of ¹⁷⁷Lu-DOTATATE in patients of PGL. Thus, ¹⁷⁷Lu-DOTATATE may be considered as promising therapeutic option in ¹³¹I-MIBG negative and SSTR positive subset of PGL cases. However, further prospective study in a large number of patients is required for validation of our study results.

Targeting pheochromocytoma/paraganglioma with polyamine inhibitors

BACKGROUND

Pheochromocytomas (PCCs) and paragangliomas (PGLs) are neuroendocrine tumors that are mostly benign. Metastatic disease does occur in about 10% of cases of PCC and up to 25% of PGL, and for these patients no effective therapies are available. Patients with mutations in the succinate dehydrogenase subunit B (SDHB) gene tend to have metastatic disease. We hypothesized that a down-regulation in the active succinate dehydrogenase B subunit should result in notable changes in cellular metabolic profile and could present a vulnerability point for successful pharmacological targeting.

METHODS

Metabolomic analysis was performed on human hPheo1 cells and shRNA SDHB knockdown hPheo1 (hPheo1 SDHB KD) cells. Additional analysis of 115 human fresh frozen samples was conducted. In vitro studies using N¹,N¹¹-diethylnorspermine (DENSPM) and N¹,N¹²- diethylspermine (DESPM) treatments were carried out. DENSPM efficacy was assessed in human cell line derived mouse xenografts.

RESULTS

Components of the polyamine pathway were elevated in hPheo1 SDHB KD cells compared to wild-type cells. A similar observation was noted in SDHx PCC/PGLs tissues compared to their non-mutated counterparts. Specifically, spermidine, and spermine were significantly elevated in SDHx-mutated PCC/PGLs, with a similar trend in hPheo1 SDHB KD cells. Polyamine pathway inhibitors DENSPM and DESPM effectively inhibited growth of hPheo1 cells in vitro as well in mouse xenografts.

CONCLUSIONS

This study demonstrates overactive polyamine pathway in PCC/PGL with SDHB mutations. Treatment with polyamine pathway inhibitors significantly inhibited hPheo1 cell growth and led to growth suppression in xenograft mice treated with DENSPM. These studies strongly implicate the polyamine pathway in PCC/PGL pathophysiology and provide new foundation for exploring the role for polyamine analogue inhibitors in treating metastatic PCC/PGL. PRéCIS: Cell line metabolomics on hPheo1 cells and PCC/PGL tumor tissue indicate that the polyamine pathway is activated. Polyamine inhibitors in vitro and in vivo demonstrate that polyamine inhibitors are promising for malignant PCC/PGL treatment. However, further research is warranted.

Clinical and genetic features of pediatric PCCs/PGLs patients: a single-center experience in China

Background

Although 40% to 80% of pediatric patients with pheochromocytoma (PCC) and paraganglioma (PGL) have been reported to carry germline mutations, the genetic and clinical features are poorly understood, and few such patients have undergone genetic testing. In this series, we aimed to investigate the clinical and genetic features of Han Chinese pediatric patients with PCC/PGL.

Methods

The medical records of 15 pediatric patients with PCC/PGL who presented to our hospital between 2006 and 2018 were retrospectively studied. DNAs isolated from leukocytes of the patients were analyzed using whole-exome sequencing (WES).

Results

The patients were nine girls and six boys with a mean age of 14.9 (range, 6–18) years. All were alive after a follow-up from 1 to 12 years, although two were diagnosed with pulmonary metastatic PGLs. Four patients were diagnosed with bilateral PCCs. Four patients were diagnosed with tumor syndromes. Among the 15 patients, nine were identified carrying germline mutations, of which seven were VHL and one each of RET and SDHB. In addition, a de novo mutation, VHL c.193T>A, was identified in a patient clinically diagnosed with a VHL syndrome.

Conclusions

Among 15 pediatric patients studied, nine were identified carrying germline genetic mutations, four were diagnosed with bilateral PCCs, and four were diagnosed with other syndromic tumors in addition to PCC, which underscores the importance of genetic testing and managing treatment accordingly.