Efficacy and safety of metyrosine in pheochromocytoma/paraganglioma: a multi-center trial in Japan

Perioperative Blood Pressure Management Recommendations in Pediatric Pheochromocytoma: A 10-Year Narrative Review

BACKGROUND

Pheochromocytomas and paragangliomas are rare chromaffin cell-derived tumors characterized by catecholamine-secreting activity. Pheochromocytomas account for 1.7% of pediatric hypertension cases. Surgical resection, the definitive pheochromocytoma treatment, carries risks of hemodynamic instability and cardiovascular complications. Nevertheless, mortality rates decreased significantly in the latter half of the 20th century due to effective perioperative blood pressure (BP) management. The literature on BP management tailored to pediatric pheochromocytoma is limited, while the sustained hypertension rate in this population is high (up to 90%) and related to a high risk of intraoperative complications. In this narrative review, we provide up-to-date recommendations regarding BP management to minimize perioperative comorbidities in children with pheochromocytoma.

SUMMARY

Antihypertensive agents, primarily alpha (α)-blockers, should be promptly administered for suspected pheochromocytoma. Beta (β)-blockers may be introduced thereafter to counteract reflex tachycardia. The patient must be salt- and water-replete preoperation. Intraoperatively, stable hemodynamics should be ensured during anesthesia and surgery, and short-acting intravenous medications and resuscitation fluid should be supplied. Postoperatively, patients should be admitted to the pediatric intensive care unit for close monitoring for at least 24-48 h. Genetic testing is recommended for all pheochromocytoma patients. Identifying underlying mutations, like in succinate dehydrogenase subunit B, which is linked to a higher risk of multifocality and metastasis, is imperative for tailoring treatment strategies and prognostication.

KEY MESSAGES

Achieving optimal outcomes in pediatric pheochromocytoma relies on preoperative BP optimization with appropriate antihypertensive agents, intraoperative hemodynamic stability, and postoperative routine long-term follow-up to monitor for complications, recurrence, and metastasis. Future research should prioritize well-designed prospective multicenter studies with adequate sample sizes and, where feasible, randomized controlled trials with standardized protocols and appropriate endpoints. These studies should focus on the efficacy and safety of preoperative nonselective versus selective α-blockers, whether as monotherapy or combined with other medications (e.g., calcium channel blockers and/or β-blockers), or treatment without preoperative anti-hypertensives.

Long-term outcomes and prognostic factors of metastatic or recurrent pheochromocytoma and paraganglioma: a 20-year review in a single institution

Pheochromocytoma and paraganglioma (PPGL) represent a group of rare neuroendocrine tumors known for their potential to metastasize. This study provides a comprehensive retrospective evaluation of 15 patients diagnosed with metastatic or recurrent PPGL at our institution over a two-decade span (2000-2020). Our primary objectives were to delineate the long-term clinical outcomes and pinpoint key prognostic determinants. Median duration from initial PPGL diagnosis to the onset of metastasis or recurrence stood at 5.8 years. Predominant sites for metastasis included the bone, lung, lymph nodes, and peritoneum. A salient finding was that surgical interventions targeting metastatic lesions significantly improved prognosis. Further analysis revealed that a Pheochromocytoma of the Adrenal Gland Scaled Score (PASS) exceeding 7 closely associated with unfavorable outcomes. These insights not only underscore the clinical variability of PPGL's progression but also highlight the pivotal role of surgical management for metastatic or recurrent cases. The value of the PASS score as an informative prognostic tool was evident, suggesting its utility in shaping future therapeutic approaches. Given the intricacies of PPGL, collaborative studies involving larger patient cohorts will be crucial to optimize management strategies and prognostication.

Adrenalectomy for pheochromocytoma: Surgical outcomes and preoperative risk factors for hemodynamic instability

BACKGROUND

Surgical resection for pheochromocytoma (PCC) is still challenging. This study assessed the perioperative outcomes of adrenalectomy for PCC and investigated the risk factors for intraoperative hemodynamic instability (HI).

METHODS

This retrospective study included 571 patients with adrenal tumors who underwent adrenalectomy at Kobe University Hospital and other related hospitals between April 2008 and October 2023. The perioperative outcomes of laparoscopic adrenalectomy were compared between PCC (n = 92) and non-PCC (n = 464) groups. In addition, we investigated several potential risk factors for intraoperative HI in patients with PCC (n = 107; open, n = 11; laparoscopic, n = 92; robot-assisted, n = 4).

RESULTS

While patients with PCC had a significantly larger amount of blood loss in comparison to those with non-PCC (mean, 70 and 30 mL, respectively; p = 0.004), no significant difference was observed in the rate of perioperative grade ≥III complications (1.1% vs. 0.6%; p = 0.516), and no perioperative mortality was observed in either group. A tumor size of ≥40 mm, with preoperative hypertension and urinary metanephrines at a level ≥3 times the upper limit of the normal value, were found to be significant predictors of HI, with odds ratios of 2.74 (p = 0.025), 3.91 (p = 0.005), and 3.83 (p = 0.004), respectively.

CONCLUSIONS

Our data suggest that laparoscopic adrenalectomy for PCC may be as safe as that for other types of adrenal tumors and that large tumors and hormonally active disease may be risk factors for intraoperative HI. The optimal perioperative management for PCC with these risk factors should be established.

The combination of doxazosin and metyrosine as a preoperative treatment for pheochromocytomas and paragangliomas

PURPOSE

Preoperative medical management is critical to prevent intraoperative cardiovascular complications in patients with pheochromocytomas and paragangliomas (PPGLs). Initial treatment involves α-adrenergic receptor blockers. However, while the routine use of metyrosine alongside these blockers is not strongly recommended due to a lack of evidence supporting its efficacy and associated safety concerns, there are previous studies on combination therapy with phenoxybenzamine and metyrosine. There are few reports on combination therapy with the selective α1-adrenergic receptor blocker doxazosin. Therefore, we investigated this combination treatment, which theoretically can affect perioperative outcomes in patients with PPGLs. To our knowledge, this is the first such study.

METHODS

This retrospective single-center observational study involved 51 patients who underwent surgical resection of PPGLs at Kobe University Hospital between 2014 and 2022. All patients received doxazosin at maximum doses. Fourteen patients received concomitant metyrosine, while 37 received doxazosin alone. Their perioperative outcomes were compared.

RESULTS

No severe event, such as acute coronary syndrome, was observed in either group. Intraoperatively, the doxazosin + metyrosine group exhibited a lower median minimum systolic blood pressure (56 [54-60] vs. 68 [59-74] mmHg, P = 0.03) and required lower median remifentanil (P = 0.04) and diltiazem (P = 0.02) doses than the doxazosin-alone group.

CONCLUSION

The combination of metyrosine and doxazosin as a preoperative treatment for PPGLs affects intraoperative circulatory hemodynamics, such as a reduced occurrence of blood pressure elevation during surgery. Further research is necessary to identify patients who will benefit most from this combination treatment.

Tyrosine Hydroxylase Inhibitors and Dopamine Receptor Agonists Combination Therapy for Parkinson's Disease

There are currently no disease-modifying therapies for Parkinson's disease (PD), a progressive neurodegenerative disorder associated with dopaminergic neuronal loss. There is increasing evidence that endogenous dopamine (DA) can be a pathological factor in neurodegeneration in PD. Tyrosine hydroxylase (TH) is the key rate-limiting enzyme for DA generation. Drugs that inhibit TH, such as alpha-methyltyrosine (α-MT), have recently been shown to protect against neurodegeneration in various PD models. DA receptor agonists can activate post-synaptic DA receptors to alleviate DA-deficiency-induced PD symptoms. However, DA receptor agonists have no therapeutic effects against neurodegeneration. Thus, a combination therapy with DA receptor agonists plus TH inhibitors may be an attractive therapeutic approach. TH inhibitors can protect and promote the survival of remaining dopaminergic neurons in PD patients' brains, whereas DA receptor agonists activate post-synaptic DA receptors to alleviate PD symptoms. Additionally, other PD drugs, such as N-acetylcysteine (NAC) and anticholinergic drugs, may be used as adjunctive medications to improve therapeutic effects. This multi-drug cocktail may represent a novel strategy to protect against progressive dopaminergic neurodegeneration and alleviate PD disease progression.

Tumor metabolism in pheochromocytomas: clinical and therapeutic implications

Pheochromocytomas and paragangliomas (PPGLs) have emerged as one of the most common endocrine tumors. It epitomizes fascinating crossroads of genetic, metabolic, and endocrine oncology, providing a canvas to explore the molecular intricacies of tumor biology. Predominantly rooted in the aberration of metabolic pathways, particularly the Krebs cycle and related enzymatic functionalities, PPGLs manifest an intriguing metabolic profile, highlighting elevated levels of oncometabolites like succinate and fumarate, and furthering cellular malignancy and genomic instability. This comprehensive review aims to delineate the multifaceted aspects of tumor metabolism in PPGLs, encapsulating genetic factors, oncometabolites, and potential therapeutic avenues, thereby providing a cohesive understanding of metabolic disturbances and their ramifications in tumorigenesis and disease progression. Initial investigations into PPGLs metabolomics unveiled a stark correlation between specific genetic mutations, notably in the succinate dehydrogenase complex (SDHx) genes, and the accumulation of oncometabolites, establishing a pivotal role in epigenetic alterations and hypoxia-inducible pathways. By scrutinizing voluminous metabolic studies and exploiting technologies, novel insights into the metabolic and genetic aspects of PPGLs are perpetually being gathered elucidating complex interactions and molecular machinations. Additionally, the exploration of therapeutic strategies targeting metabolic abnormalities has burgeoned harboring potential for innovative and efficacious treatment modalities. This review encapsulates the profound metabolic complexities of PPGLs, aiming to foster an enriched understanding and pave the way for future investigations and therapeutic innovations in managing these metabolically unique tumors.

[French recommendations for malignant pheochromocytomas and paragangliomas by the national ENDOCAN-COMETE network]

Pheochromocytomas and paragangliomas are rare neuroendocrine tumors, developed respectively in the adrenal medulla and in extra-adrenal locations. Their malignancy is defined by the presence of distant metastases. Forty percent of them are inherited and can be part of different hereditary syndromes. Their management is ensured in France by the multidisciplinary expert centers of the ENDOCAN-COMETE national network "Cancers of the Adrenal gland", certified by the National Cancer Institute and discussed within multidisciplinary team meetings. The diagnostic and therapeutic work-up must be standardized, based on an expert analysis of clinical symptoms, hormonal biological secretions, genetics, morphological and specific metabolic imaging. In the context of a heterogeneous survival sometimes beyond seven to ten years, therapeutic intervention must be justified. This is multidisciplinary and relies on surgery, interventional radiology, external or internal radiotherapy and medical treatments such as sunitinib or dacarbazine and temodal chemotherapy. The personalized approach based on functional imaging fixation status and genetics is progressing despite the extreme rarity of this disease.

Repeat hepatectomy for massive liver metastases from pheochromocytoma: a case report

In malignant pheochromocytoma, the survival benefit of metastasectomy remains unclear. However, excessive catecholamines secreted from pheochromocytomas can cause cardiovascular and cerebrovascular complications. Debulking metastasectomy can be performed to reduce excess catecholamine secretion when curative resection is impossible. We present a case of metastatic pheochromocytoma to the liver, wherein a significant reduction in catecholamine secretion was achieved by repeat debulking hepatectomy. A 62-year-old woman who had undergone left adrenalectomy for primary pheochromocytoma 10 years prior to our surgical management, had multiple liver metastases of pheochromocytoma. Curative hepatectomy was infeasible because of insufficient remnant liver volume; thus, debulking hepatectomy was conducted. Preoperatively, increased doses of alpha-blockers and catecholamine synthesis inhibitors were administered. Nevertheless, substantial fluctuations in blood pressure and massive hemorrhage were observed intraoperatively. Eight months after the initial hepatectomy, repeat hepatectomy for the remnant lesions was performed due to the worsening of catecholamine levels and catecholamine-related symptoms. The patient survived, with serum catecholamines remaining within the normal range after repeat hepatectomy. Repeat debulking hepatectomy for metastatic pheochromocytoma to the liver is a feasible treatment strategy to effectively decrease catecholamine secretion and alleviate the symptoms thereof. However, special attention should be paid to perioperative catecholamine management and intraoperative surgical techniques.

Adrenal Lesions: A Review of Imaging

Adrenal lesions are frequently incidentally diagnosed during investigations for other clinical conditions. Despite being usually benign, nonfunctioning, and silent, they can occasionally cause discomfort or be responsible for various clinical conditions due to hormonal dysregulation; therefore, their characterization is of paramount importance for establishing the best therapeutic strategy. Imaging techniques such as ultrasound, computed tomography, magnetic resonance, and PET-TC, providing anatomical and functional information, play a central role in the diagnostic workup, allowing clinicians and surgeons to choose the optimal lesion management. This review aims at providing an overview of the most encountered adrenal lesions, both benign and malignant, including describing their imaging characteristics.

Development of early diagnosis of Parkinson's disease on animal models based on the intranasal administration of α-methyl-p-tyrosine methyl ester in a gel system

The fight against neurodegenerative diseases, including Parkinson's disease (PD), is a global challenge of this century. The effectiveness of current PD therapy is limited, since it is diagnosed many years after the onset, following the death of most nigrostriatal dopaminergic neurons regulating motor function. PD treatment could be greatly improved if it was started at an early (preclinical) stage. For this purpose, it is necessary to develop an early diagnosis of PD, which is the goal of our study. We have developed an early diagnosis of PD on animal models using a provocative test by intranasal administration of α-methyl-p-tyrosine methyl ester (αMPTME), a reversible inhibitor of dopamine synthesis. First, we produced the provocative agent, αMPTME in gel, and showed its safety and penetration into the brain bypassing the blood-brain barrier. Then, the optimal dose of αMPTME and time after administration were selected, at which the level of dopamine in the striatum of intact animals decreases, but does not reach the 30% threshold for the appearance of motor disorders in PD patients. Finally, we proved on animal models that intranasal administration of αMPTME can serve as a diagnostic test for preclinical PD. Indeed, intranasal administration of αMPTME to mice in a model of PD at the preclinical stage reversibly reduced the dopamine level in the striatum to the 30% threshold causing short-term motor disorders. Thus, using animal models of PD, we have developed a provocative test for the preclinical diagnosis of PD, a fundamentally new technology in neurology.

Personalized Management of Pheochromocytoma and Paraganglioma

Pheochromocytomas/paragangliomas are characterized by a unique molecular landscape that allows their assignment to clusters based on underlying genetic alterations. With around 30% to 35% of Caucasian patients (a lower percentage in the Chinese population) showing germline mutations in susceptibility genes, pheochromocytomas/paragangliomas have the highest rate of heritability among all tumors. A further 35% to 40% of Caucasian patients (a higher percentage in the Chinese population) are affected by somatic driver mutations. Thus, around 70% of all patients with pheochromocytoma/paraganglioma can be assigned to 1 of 3 main molecular clusters with different phenotypes and clinical behavior. Krebs cycle/VHL/EPAS1-related cluster 1 tumors tend to a noradrenergic biochemical phenotype and require very close follow-up due to the risk of metastasis and recurrence. In contrast, kinase signaling-related cluster 2 tumors are characterized by an adrenergic phenotype and episodic symptoms, with generally a less aggressive course. The clinical correlates of patients with Wnt signaling-related cluster 3 tumors are currently poorly described, but aggressive behavior seems likely. In this review, we explore and explain why cluster-specific (personalized) management of pheochromocytoma/paraganglioma is essential to ascertain clinical behavior and prognosis, guide individual diagnostic procedures (biochemical interpretation, choice of the most sensitive imaging modalities), and provide personalized management and follow-up. Although cluster-specific therapy of inoperable/metastatic disease has not yet entered routine clinical practice, we suggest that informed personalized genetic-driven treatment should be implemented as a logical next step. This review amalgamates published guidelines and expert views within each cluster for a coherent individualized patient management plan.

Pheochromocytoma, Fulminant Heart Failure, and a Phenylephrine Challenge. The Perioperative Management of Adrenalectomy in a Jehovah’s Witness Patient: A Case Report

Perioperative management of pheochromocytoma in the setting of catecholamine-induced heart failure requires careful consideration of hemodynamic optimization and possible mechanical circulatory support. A Jehovah’s Witness patient with catecholamine-induced acutely decompensated heart failure required dependable afterload reduction for a cardio-protective strategy. This was emphasized due to the relative contraindication to perioperative anticoagulation required for mechanical circulatory support. A phenylephrine challenge clearly demonstrated adequate alpha blockade after only 24 hours of phenoxybenzamine treatment. This resulted in advancement of the surgery date. This case also highlights management of beta blockade, volume and salt loading, autologous blood transfusion, and profound post-operative vasoplegia in the setting of cardiogenic shock. Careful attention to hemodynamic optimization and cardio-protective strategies ultimately resulted in positive outcome for this challenging clinical scenario.

Pheochromocytomas and paragangliomas

PURPOSE OF REVIEW

Great progress has been made in understanding the genetic and molecular basis of pheochromocytoma and paragangliomas (PPGLs). This review highlights the new standards in the diagnosis and management of pediatric PPGLs.

RECENT FINDINGS

The vast majority of pediatric PPGLs have an associated germline mutation, making genetic studies imperative in the work up of these tumors. Somatostatin receptor-based imaging modalities such as 68Ga-DOTATATE and 64Cu-DOTATATE are shown to have the greatest sensitivity in pediatric PPGLs. Peptide receptor radionuclide therapies (PRRTs) such as 177Lu-DOTATATE are shown to have efficacy for treating PPGLs.

SUMMARY

Genetics play an important role in pediatric PPGLs. Advances in somatostatin receptor-based technology have led to use of 68Ga-DOTATATE and 64Cu-DOTATATE as preferred imaging modalities. While surgery remains the mainstay for management of PPGLs, PRRT is emerging as a treatment option for PPGLs.

Targeting Tyrosine Hydroxylase for Abdominal Aortic Aneurysm: Impact on Inflammation, Oxidative Stress, and Vascular Remodeling

[Figure: see text].

CAR-T Cell Therapy: Mechanism, Management, and Mitigation of Inflammatory Toxicities

Engineered T cell therapies such as chimeric antigen receptor (CAR) expressing T cells (CAR-T cells) have great potential to treat many human diseases; however, inflammatory toxicities associated with these therapies present safety risks and can greatly limit its widespread use. This article briefly reviews our current understanding of mechanisms for inflammatory toxicities during CAR T-cell therapy, current strategies for management and mitigation of these risks and highlights key areas of knowledge gap for future research.

Pheochromocytoma/paraganglioma crisis: case series from a tertiary referral center for pheochromocytomas and paragangliomas

Pheochromocytoma/paraganglioma (PPGL)-induced catecholamine crisis is a rare endocrine emergency leading to life-threatening hemodynamic instability causing end-organ damage or dysfunction. As it is associated with a significant mortality rate of approximately 15%, recognizing the signs and symptoms and making the appropriate diagnosis are critical. For this purpose, we report the clinical course of the crisis in four out of a total of six patients with a PPGL crisis from a cohort of 199 PPGL patients of a single tertiary referral center for PPGL patients in the Netherlands diagnosed between 2002 and 2020. Successful treatment of a PPGL crisis demands prompt diagnosis, vigorous pharmacological therapy, and emergency tumor removal if the patient continues to deteriorate.

The Role for Metyrosine in the Treatment of Patients With Pheochromocytoma and Paraganglioma

CONTEXT

Treatment of pheochromocytoma and paraganglioma (PPGL) requires preintervention titration of alpha- and beta-adrenergic blockade, but patients may still be at risk for complications from catecholamine excess. Metyrosine decreases catecholamine production, making it an attractive therapeutic adjunct for select patients.

EVIDENCE ACQUISITION

A systematic literature review was performed (Ovid Medline and Scopus databases) on December 17, 2019, including studies with humans and original data. Studies with 10 or more patients on metyrosine for PPGL were included. Studies were screened for overlapping populations, and the most comprehensive study was included. The references of included studies were reviewed for additional data. Patient data from our institution between 2000 and 2015 were also reviewed.

EVIDENCE SYNTHESIS

Metyrosine is well tolerated when used for a short course and can improve intraoperative outcomes in PPGL. Metyrosine should be considered when a difficult PPGL resection is expected (eg, pericardiac paraganglioma, abdominal paraganglioma with great vessel involvement), a large release of catecholamines is anticipated (eg, ablative therapy, chemotherapy), or when standard alpha- and beta-adrenergic blockade are not tolerated or cannot adequately control hypertension. Side effects are generally mild and self-limited, with sedation in a majority of patients. Extrapyramidal side effects are rare but can limit use of metyrosine. Because of its expense and limited availability, metyrosine use should be carefully planned and timed in relation to surgery.

CONCLUSIONS

Metyrosine is a safe addition to traditional alpha- and beta-adrenergic blockade and should be considered in those patients with PPGL at high risk for acute release of catecholamines.

Metastatic Pheochromocytomas and Abdominal Paragangliomas

CONTEXT

Pheochromocytomas and paragangliomas (PPGLs) are believed to harbor malignant potential; about 10% to 15% of pheochromocytomas and up to 50% of abdominal paragangliomas will exhibit metastatic behavior.

EVIDENCE ACQUISITION

Extensive searches in the PubMed database with various combinations of the key words pheochromocytoma, paraganglioma, metastatic, malignant, diagnosis, pathology, genetic, and treatment were the basis for the present review.

DATA SYNTHESIS

To pinpoint metastatic potential in PPGLs is difficult, but nevertheless crucial for the individual patient to receive tailor-made follow-up and adjuvant treatment following primary surgery. A combination of histological workup and molecular predictive markers can possibly aid the clinicians in this aspect. Most patients with PPGLs have localized disease and may be cured by surgery. Plasma metanephrines are the main biochemical tests. Genetic testing is important, both for counseling and prognostic estimation. Apart from computed tomography and magnetic resonance imaging, molecular imaging using 68Ga-DOTATOC/DOTATATE should be performed. 123I-MIBG scintigraphy may be performed to determine whether 131I-MIBG therapy is a possible option. As first-line treatment in patients with metastatic disease, 177Lu-DOTATATE or 131I-MIBG is recommended, depending on which shows best expression. In patients with very low proliferative activity, watch-and-wait or primary treatment with long-acting somatostatin analogues may be considered. As second-line treatment, or first-line in patients with high proliferative rate, chemotherapy with temozolomide or cyclophosphamide + vincristine + dacarbazine is the therapy of choice. Other therapies, including sunitinib, cabozantinib, everolimus, and PD-1/PDL-1 inhibitors, have shown modest effect.

CONCLUSIONS

Metastatic PPGLs need individualized management and should always be discussed in specialized and interdisciplinary tumor boards. Further studies and newer treatment modalities are urgently needed.

Methylated derivatives of l-tyrosine in reaction catalyzed by l-amino acid oxidase: isotope and inhibitory effects

l-Amino acid oxidase (LAAO) is widely distributed in nature and shows important biological activity. It induces cell apoptosis and has antibacterial properties. This study was designed to investigate the effect of methyl substituent on its activity as methylated derivatives of l-tyrosine, labelled with short-lived B+ emitters, have been used in oncological diagnostics. To study isotope effects in the oxidative deamination of O-methyl-l-tyrosine, the deuterated isotopomer, i.e. O-methyl-[2-2H]-l-tyrosine, was synthesized by isotope exchange, catalyzed enzymatically by tryptophanase. Isotope effects were determined using the spectrophotometric non-competitive method. The values of isotope effects indicate that the α-C-H bond cleavage occurs in the rate determining step of the investigated reaction and α-hydrogen plays a role in the substrate binding process at the enzyme active site. The inhibitory effect on LAAO activity was studied with α-methyl-l-tyrosine and N-methyl-l-tyrosine. The mode of inhibition was determined based on Lineweavear-Burk plots intersections. α-Methyl-l-tyrosine has been found a mixed type inhibitor of the investigated enzyme, whereas N-methyl-l-tyrosine is a non-competitive inhibitor of LAAO.

Recent advances in the management of pheochromocytoma and paraganglioma

Pheochromocytomas and paragangliomas (PPGLs) are rare tumors that cause refractory hypertension and hypertensive crisis. Although metastatic disease accounts for 30% of PPGLs, the diagnosis of malignancy is difficult without the presence of metastatic lesions. Here, we review several advancements in the diagnosis and treatment of PPGL. A nationwide epidemiological survey in Japan revealed that the annual number of patients with PPGL was 3000, which was higher than that reported previously. While plasma and urine fractionated metanephrines are recommended for use in specific biochemical testing for diagnosis, creatinine-corrected fractionated metanephrines in spot urine samples that had been widely used in Japan as a convenient screening test were shown to be as useful as 24-h urine fractionated metanephrines. Regarding imaging studies, a more specific functional imaging for PPGLs, ⁶⁸Ga DOTATATE, was newly developed. ⁶⁸Ga DOTATATE provides a clear image with high sensitivity and specificity. Currently, PASS or GAPP histological scores and SDHB immunostaining are clinically used to attempt to discriminate benign from malignant tumors. However, since this distinguishing process remains difficult, all cases were classified as malignant with the possibility of metastasis in the WHO classification of endocrine tumors updated in 2017. Approximately 60% of PPGLs have germline mutations in PPGL-related genes. Currently, the genes are classified into two clusters based on their mechanism for the etiology of tumorigenesis. Based on the possible mechanisms of tumor development associated with gene mutations, several molecular target drugs are under evaluation to explore more promising treatments for malignant PPGL.

Pheochromocytoma

Pheochromocytomas are rare tumors originating in the adrenal medulla. They may be sporadic or in the context of a hereditary syndrome. A considerable number of pheochromocytomas carry germline or somatic gene mutations, which are inherited in the autosomal dominant way. All patients should undergo genetic testing. Symptoms are due to catecholamines over production or to a mass effect. Diagnosis is confirmed by raised plasma or urine metanephrines or normetanephrines. Radiology assists in the tumor location and any local invasion or metastasis. All the patients should have preoperative preparation with α-blockers and/or other medications to control hypertension, arrhythmia, and volume expansion. Surgery is the definitive treatment. Follow up should be life-long.

Preoperative Management of Pheochromocytoma and Paraganglioma

Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors, characterized by excessive release of catecholamines (CAs), and manifested as the classic triad of headaches, palpitations, profuse sweating, and a variety of other signs and symptoms. The diagnosis of PPGL requires both evidence of excessive release of CAs and anatomical localization of CA-secreting tumor. Surgery is the mainstay of treatment for all patients with PPGL unless contraindicated. However, without proper preparation, the release of excessive CAs, especially during surgery, can result in lethal cardiovascular complications. Herein, we briefly reviewed the pathogenesis of this disease, discussed the current approaches and evidence available for preoperative management, summarizing the results of the latest studies which compared the efficacies of preoperative management with or without α adrenergic-receptor antagonists, aiming to facilitate better understanding of the preoperative management of PPGL for the physicians.

Correlation between urinary fractionated metanephrines in 24-hour and spot urine samples for evaluating the therapeutic effect of metyrosine: a subanalysis of a multicenter, open-label phase I/II study

We recently conducted an open-label phase I/II study to evaluate the efficacy and safety of preoperative and chronic treatment with metyrosine (an inhibitor of catecholamine synthesis) in pheochromocytoma/paraganglioma (PPGL) in Japan. We compared creatinine-corrected metanephrine fractions in spot urine and 24-hour urine samples (the current standard for the screening and diagnosis of PPGLs) from 16 patients to assess the therapeutic effect of metyrosine. Percent changes from baseline in urinary metanephrine (uMN) or normetanephrine (uNMN) were compared between spot and 24-hour urine samples. Mean percent changes in uMN or uNMN in spot and 24-hour urine were -26.36% and -29.27%, respectively. The difference in the percent change from baseline between uMN or uNMN in spot and 24-hour urine was small (-2.90%). The correlation coefficient was 0.87 for percent changes from baseline between uMN or uNMN measured in spot and 24-hour urine. The area under the receiver operator characteristic (ROC) curve of uMN or uNMN measured in spot urine vs. 24-hour urine (reference standard) to assess the efficacy of metyrosine treatment was 0.93. Correlations and ROCs between 24-hour urinary vanillylmandelic acid, adrenaline, and noradrenaline and 24-hour uMN or uNMN were similar to those between spot uMN or uNMN and 24-hour uMN or uNMN. No large difference was observed between spot and 24-hour urine for the assessment of metyrosine treatment by quantifying uMN or uNMN in Japanese patients with PPGLs. These results suggest that spot urine samples may be useful in assessing the therapeutic effect of metyrosine.

Dopaminergic impact of cART and anti-depressants on HIV neuropathogenesis in older adults

The success of combination antiretroviral therapy (cART) has transformed HIV infection into a chronic condition, resulting in an increase in the number of older, cART-treated adults living with HIV. This has increased the incidence of age-related, non-AIDS comorbidities in this population. One of the most common comorbidities is depression, which is also associated with cognitive impairment and a number of neuropathologies. In older people living with HIV, treating these overlapping disorders is complex, often creating pill burden or adverse drug-drug interactions that can exacerbate these neurologic disorders. Depression, NeuroHIV and many of the neuropsychiatric therapeutics used to treat them impact the dopaminergic system, suggesting that dopaminergic dysfunction may be a common factor in the development of these disorders. Further, changes in dopamine can influence the development of inflammation and the regulation of immune function, which are also implicated in the progression of NeuroHIV and depression. Little is known about the optimal clinical management of drug-drug interactions between cART drugs and antidepressants, particularly in regard to dopamine in older people living with HIV. This review will discuss those interactions, first examining the etiology of NeuroHIV and depression in older adults, then discussing the interrelated effects of dopamine and inflammation on these disorders, and finally reviewing the activity and interactions of cART drugs and antidepressants on each of these factors. Developing better strategies to manage these comorbidities is critical to the health of the aging, HIV-infected population, as the older population may be particularly vulnerable to drug-drug interactions affecting dopamine.