Sequelae and survivorship in patients treated with (131)I-MIBG therapy

Theranostics in Neuroendocrine Tumors

ABSTRACT

Neuroendocrine tumors (NETs) are rare tumors that develop from cells of the neuroendocrine system and can originate in multiple organs and tissues such as the bowels, pancreas, adrenal glands, ganglia, thyroid, and lungs. This review will focus on gastroenteropancreatic NETs (more commonly called NETs) characterized by frequent somatostatin receptor (SSTR) overexpression and pheochromocytomas/paragangliomas (PPGLs), which typically overexpress norepinephrine transporter. Advancements in SSTR-targeted imaging and treatment have revolutionized the management of patients with NETs. This comprehensive review delves into the current practice, discussing the use of the various Food and Drug Administration-approved SSTR-agonist positron emission tomography tracers and the predictive imaging biomarkers, and elaborating on 177Lu-DOTATATE peptide receptor radionuclide therapy including the evolving areas of posttherapy imaging practices and peptide receptor radionuclide therapy retreatment. SSTR-targeted imaging and therapy can also be used in patients with PPGL; however, this patient population has demonstrated the best outcomes from norepinephrine transporter-targeted therapy with 131I-metaiodobenzylguanidine. Metaiodobenzylguanidine theranostics for PPGL will be discussed, noting that in 2024 it became commercially unavailable in the United States. Therefore, the use and reported success of SSTR theranostics for PPGL will also be explored.

Cardiac 123I-Metaiodobenzylguanidine (MIBG) Scintigraphy in Parkinson's Disease: A Comprehensive Review

Cardiac sympathetic denervation, as documented on 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, is relatively sensitive and specific for distinguishing Parkinson's disease (PD) from other neurodegenerative causes of parkinsonism. The present study aims to comprehensively review the literature regarding the use of cardiac MIBG in PD. MIBG is an analog to norepinephrine. They share the same uptake, storage, and release mechanisms. An abnormal result in the cardiac MIBG uptake in individuals with parkinsonism can be an additional criterion for diagnosing PD. However, a normal result of cardiac MIBG in individuals with suspicious parkinsonian syndrome does not exclude the diagnosis of PD. The findings of cardiac MIBG studies contributed to elucidating the pathophysiology of PD. We investigated the sensitivity and specificity of cardiac MIBG scintigraphy in PD. A total of 54 studies with 3114 individuals diagnosed with PD were included. The data were described as means with a Hoehn and Yahr stage of 2.5 and early and delayed registration H/M ratios of 1.70 and 1.51, respectively. The mean cutoff for the early and delayed phases were 1.89 and 1.86. The sensitivity for the early and delayed phases was 0.81 and 0.83, respectively. The specificity for the early and delayed phases were 0.86 and 0.80, respectively.

Management of non-hepatic distant metastases in neuroendocrine neoplasms

Neuroendocrine neoplasms represent an uncommon disease with an increasing incidence. Thanks to improvements in diagnostic and therapeutic methods, metastases previously considered uncommon, such as bone metastases, or even very rare, such as brain, orbital and cardiac metastases, are more frequently found in daily practice. Due to the great heterogeneity of these neoplasms, there is a lack of high-quality evidence on the management of patients with these types of metastases. The aim of this review is to provide the current state of the art, reviewing neuroendocrine neoplasm specific studies and useful information from other tumor types and to propose a treatment recommendation with algorithms to consider in daily clinical practice.

Recent Advances in Radiopharmaceutical Theranostics of Pheochromocytoma and Paraganglioma

As a rare kind of non-epithelial neuroendocrine neoplasms, paragangliomas (PGLs) exhibit various clinical characteristics with excessive catecholamine secretion and have been a research focus in recent years. Although several modalities are available nowadays, radiopharmaceuticals play an integral role in the management of PGLs. Theranostics utilises radiopharmaceuticals for diagnostic and therapeutic intentions by aiming at a specific target in tumour and has been considered a possible means in diagnosis, staging, monitoring and treatment planning. Numerous radiopharmaceuticals have been developed over the past decades. 123/131-Metaiodobenzylguanidine (123/131I-MIBG), the theranostics pair target on norepinephrine transporter system, has remained a fantastic protocol for patients with PGLs because of disease control with limited toxicity. The high-specific-activity 131I-MIBG was authorised by the Food and Drug Administration as a systemic treatment method for metastatic PGLs in 2018. Afterward, peptide receptor radionuclide therapy, which uses radiolabelled somatostatin (SST) analogues, has been exploited as a superior substitute. 68Ga-somatostatin analogue (SSA) PET showed significant performance in diagnosing PGLs than MIBG scintigraphy, especially in patients with head and neck PGLs or SDHx mutation. 90Y/177Lu-DOTA-SSA is highly successful and has preserved favourable safety with mounting evidence regarding objective response, disease stabilisation, symptomatic and hormonal management and quality of life preservation. Besides the ordinary beta emitters, alpha-emitters such as 211At-MABG and 225Ac-DOTATATE have been investigated intensively in recent years. However, many studies are still in the pre-clinical stage, and more research is necessary. This review summarises the developments and recent advances in radiopharmaceutical theranostics of PGLs.

Role of imaging test with radionuclides in the diagnosis and treatment of pheochromocytomas and paragangliomas

Radionuclide imaging tests with [¹²³I] Metaiodobenzylguanidine (MIBG), [¹⁸F] -fluorodeoxyglucose, [¹⁸F]-fluorodopa, or ⁶⁸Ga-DOTA(0)-Tyr(3)-octreotate are useful for the diagnosis, staging and follow-up of pheochromocytomas (PHEOs) and paragangliomas (PGLs) (PPGLs). In addition to their ability to detect and localize the disease, they allow a better molecular characterization of the tumours, which is useful for planning targeted therapy with iodine-131 (¹³¹I) -labelled MIBG or with peptide receptor radionuclide therapy (PRRT) with [¹⁷⁷Lu]-labelled DOTATATE or other related agents in patients with metastatic disease. In this review we detail the main characteristics of the radiopharmaceuticals used in the functional study of PPGLs and the role of nuclear medicine tests for initial evaluation, staging, selection of patients for targeted molecular therapy, and radiation therapy planning. It also offers a series of practical recommendations regarding the functional imaging according to the different clinical and genetic scenarios in which PPGLs occur, and on the indications and efficacy of therapy with [¹³¹I]-MIBG and ¹⁷⁷Lu-DOTATATE.

I-131 metaiodobenzylguanidine therapy is a significant treatment option for pheochromocytoma and paraganglioma

AIM

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumours of chromaffin cells. Several modalities are currently available to treat patients with PPGL. These treatment modalities include surgery, chemotherapy, molecular targeted therapy and radiopharmaceuticals.

METHODS

I-131 metaiodobenzylguanidine (mIBG), a classic radiopharmaceutical, can be taken up through specific receptors and sited into many, but not all, PPGL cells.

RESULTS

Many studies have investigated the efficacy and toxicity of I-131 mIBG therapy. These studies reported significant results in terms of objective, hormonal and symptomatic responses as well as tolerable toxicities in patients.

CONCLUSION

This article reviews the reported experiences of patients who underwent I-131 mIBG therapy for PPGL with a focus on functions and deficiencies of the therapy.

Metastatic medullary thyroid carcinoma: a new way forward

Medullary thyroid carcinoma (MTC) is a rare malignancy comprising 1-2% of all thyroid cancers in the United States. Approximately 20% of cases are familial, secondary to a germline RET mutation, while the remaining 80% are sporadic and also harbour a somatic RET mutation in more than half of all cases. Up to 15-20% of patients will present with distant metastatic disease, and retrospective series report a 10-year survival of 10-40% from time of first metastasis. Historically, systemic therapies for metastatic MTC have been limited, and cytotoxic chemotherapy has demonstrated poor objective response rates. However, in the last decade, targeted therapies, particularly multitargeted tyrosine kinase inhibitors (TKIs), have demonstrated prolonged progression-free survival in advanced and progressive MTC. Both cabozantinib and vandetanib have been approved as first-line treatment options in many countries; nevertheless, their use is limited by high toxicity rates and dose reductions are often necessary. New generation TKIs, such as selpercatinib or pralsetinib, that exhibit selective activity against RET, have recently been approved as a second-line treatment option, and they exhibit a more favourable side-effect profile. Peptide receptor radionuclide therapy or immune checkpoint inhibitors may also constitute potential therapeutic options in specific clinical settings. In this review, we aim to present all current therapeutic options available for patients with progressive MTC, as well as new or as yet experimental treatments.

Priming and Propagating Anti-tumor Immunity: Focal Hypofractionated Radiation for in Situ Vaccination and Systemic Targeted Radionuclide Theranostics for Immunomodulation of Tumor Microenvironments

Recent preclinical and clinical studies have elucidated mechanisms whereby radiation therapy influences the anti-tumor immune response. Immunogenic cell death and phenotypic changes in tumor cells surviving radiation may underlie this effect and contribute to the capacity of radiation to elicit an in situ tumor vaccine effect. In situ vaccination is a therapeutic strategy that seeks to convert a patient's own tumor into a source of enhanced antigen recognition for the purpose of augmenting a systemic anti-tumor immune response. Capitalizing on the in situ vaccine effect of radiation, several groups have demonstrated anti-tumor efficacy in preclinical models by combining radiation with immune checkpoint blockade. Local delivery of immune adjuvants and/or immune stimulatory cytokines via direct injection into the radiated tumor microenvironment may further increase the in situ vaccine capacity of radiation therapy. However, recent studies suggest that in some contexts this effect is antagonized by the presence of distant untreated sites of disease that may dampen the systemic immune response generated by in situ vaccination through a phenomenon termed concomitant immune tolerance. Concomitant immune tolerance may be overcome by delivering radiation to all sites of metastatic disease, however this is often not possible to safely achieve using external beam radiation therapy without considerable risk of lymphopenia that would negate the immune effects of in situ vaccination. For patients with widespread metastatic disease, alternative strategies may include systemic treatment with targeted radionuclide therapies alone or in combination with an external beam radiation therapy-based in situ vaccine approach.

Combination radionuclide therapy: A new paradigm

Targeted molecular radionuclide therapy (MRT) has shown its potential for the treatment of cancers of multiple origins. A combination therapy strategy employing two or more distinct therapeutic approaches in cancer management is aimed at circumventing tumor resistance by simultaneously targeting compensatory signaling pathways or bypassing survival selection mutations acquired in response to individual monotherapies. Combination radionuclide therapy (CRT) is a newer application of the concept, utilizing a combination of radiolabeled molecular targeting agents with chemotherapy and beam radiation therapy for enhanced therapeutic index. Encouraging results are reported with chemotherapeutic agents in combination with radiolabeled targeting molecules for cancer therapy. With increasing awareness of the various survival and stress response pathways activated after radionuclide therapy, different holistic combinations of MRT agents with radiosensitizers targeting such pathways have also been explored. MRT has also been studied in combination with beam radiotherapy modalities such as external beam radiation therapy and carbon ion radiation therapy to enhance the anti-tumor response. Nanotechnology aids in CRT by bringing together multiple monotherapies on a single nanostructure platform for treating cancers in a more precise or personalized way. CRT will be a key player in managing cancers if correctly tailored to the individual patient profile. The success of CRT lies in an in-depth understanding of the radiobiological principles and pathways activated in response.

Knowns and unknowns of bone metastases in patients with neuroendocrine neoplasms: A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to develop an evidence-based summary of current knowledge of bone metastases (BMs) in neuroendocrine neoplasms (NENs), inform diagnosis and treatment and standardise management between institutions.

METHODS

PubMed, Medline, EMBASE and meeting proceedings were searched for eligible studies reporting data on patients with BMs and NENs of any grade of differentiation and site; poorly-differentiated large/small cell lung cancer were excluded. Data were extracted and analysed using STATA v.12. Meta-analysis of proportions for calculation of estimated pooled prevalence of BM and calculation of weighted pooled frequency and weighted pooled mean for other variables of interest was performed .

RESULTS

A total of 149 studies met the eligibility criteria. Pooled prevalence of BMs was 18.4% (95% CI 15.4-21.5). BMs were mainly metachronous with initial diagnosis of NEN (61.2%) and predominantly osteoblastic; around 61% were multifocal, with a predisposition in axial skeleton. PET/CT seemed to provide (together with MRI) the highest sensitivity and specificity for BM detection. Almost half of patients (46.4%) reported BM-related symptoms: pain (66%) and skeletal-related events (SREs, fracture/spinal cord compression) (26.2%; weightedweighted mean time-to-SRE 9.9 months). Management of BMs was multimodal [bisphosphonates and bone-modifying agents (45.2%), external beam radiotherapy (34.9%), surgery (14.8%)] and supported by little evidence. Overall survival (OS) from the time of diagnosis of BMs was long [weighted mean 50.9 months (95% CI 40.0-61.9)]. Patients with BMs had shorter OS [48.8 months (95% CI 37.9-59.6)] compared to patients without BMs [87.4 months (95% CI 74.9-100.0); p = 0.001]. Poor performance status and BM-related symptoms were also associated with worse OS.

CONCLUSIONS

BMs in patients with NENs remain underdiagnosed and undertreated. Recommendations for management of BMs derived from current knowledge are provided. Prospective studies to inform management are required.

Management and outcome of metastatic pheochromocytomas/paragangliomas: an overview

BACKGROUND

Metastatic pheochromocytomas and paragangliomas (PPGLs) occur in about 5-26% of cases and are characterized by a heterogeneous prognosis. Metastases can be synchronous at the initial diagnosis, but they can occur also many years after surgery for the primary tumor. To date, the treatment of patients affected by metastatic PPGLs represents a clinical challenge because of the lack of guidelines.

AIM

The aim of this article is to review the available management options and their impact on the outcomes of patients with metastatic PPGLs.

RESULTS

Generally, treatments are not curative. Surgery, when possible, can be used to reduce hormonal symptoms and cardiovascular morbidity. Chemotherapy plays a role in patients with high burden tumor and rapid disease progression. Tyrosine kinases inhibitors (TKIs) might be considered for their ability to block the angiogenesis and cell growth. Radiation therapy and interventional radiology techniques can help in the management of local metastases to control symptoms and avoid tumor progression. On the other hand, peptide receptor radionuclide therapy (PRRT), using ⁹⁰Y or ¹⁷⁷Lu-DOTATATE, could be a promising therapy. In addition, high specific ¹³¹I-MIBG was approved by the Food and Drug Administration (FDA) in the US for the treatment of patients affected by metastatic and unresectable ¹³¹I-MIBG positive PPGLs. Considering the different pathways involved in the pathogenesis of PPGLs, several target therapies have been proposed and are under evaluation in clinical trials.

CONCLUSIONS

The choice of the appropriate treatment should be based on multidisciplinary and personalized approach taking into account the rarity and the variability of these tumors.

The Promise of Combining Radiation Therapy With Immunotherapy

The development of immunotherapy in oncology builds upon many years of scientific investigation into the cellular mechanics underlying interactions between tumor cells and immune cell populations. The past decade has brought an accelerating pace to the clinical investigation of new immunotherapy agents, particularly in the setting of metastatic disease. The integration of immunotherapy into phase 3 clinical trial design has lagged in settings of advanced locoregional disease, where combination with radiation therapy may be critical. Yet, such may be the settings where immunotherapies have their greatest potential to affect patient survival and achieve curative outcomes. In this review, we discuss the interaction of radiation with the immune system and the potential to augment antitumor immunity through combined-modality approaches that integrate radiation and immunotherapies. The dynamics of cellular and tumor response to radiation offer unique opportunities for beneficial interplay with immunotherapy that may go unrecognized with conventional screening and monotherapy clinical testing of novel pharmaceutical agents. Using immune checkpoint blockade as a primary example, we discuss recent preclinical and clinical studies that illustrate the potential synergy of such therapies in combination with radiation, and we highlight the potential clinical value of such interactions. For various immunotherapy agents, their greatest clinical effect may rest in combination with radiation, and efforts to facilitate systematic investigation of this approach are highly warranted.

Metastatic pheochromocytoma and paraganglioma: Management of endocrine manifestations, surgery and ablative procedures, and systemic therapies

Metastatic pheochromocytomas and paragangliomas (MPPGs) are rare neuroendocrine tumors. Most patients present with advanced disease that is associated with manifestations of catecholamine release. Surgical resection of the primary tumor and ablative therapies of metastases-whenever possible-may improve clinical outcomes and, perhaps, lengthen the patient's overall survival. Significant steps in understanding the genetic alterations linked to MPPGs and scientific progress made on cancers that share a similar pathogenesis are leading to the recognition of potential systemic therapeutic options. Data derived from clinical trials evaluating targeted therapies such as tyrosine kinase inhibitors, radiopharmaceuticals, immunotherapy, and combinations of these will likely improve the outcomes of patients with advanced and progressive MPPGs. Exemplary of this success is the recent approval in the United States of the high-specific-activity iodine¹³¹ meta-iodine-benzylguanidine (MIBG) for patients with unresectable and progressive MPPGs that express the noradrenaline transporter. This review will discuss the therapeutic approaches for patients with MPPGs.

Current Management of Pheochromocytoma/Paraganglioma: A Guide for the Practicing Clinician in the Era of Precision Medicine

Pheochromocytomas and paragangliomas (PCC/PGLs) are rare, mostly catecholamine-producing neuroendocrine tumors of the adrenal gland (PCCs) or the extra-adrenal paraganglia (PGL). They can be separated into three different molecular clusters depending on their underlying gene mutations in any of the at least 20 known susceptibility genes: The pseudohypoxia-associated cluster 1, the kinase signaling-associated cluster 2, and the Wnt signaling-associated cluster 3. In addition to tumor size, location (adrenal vs. extra-adrenal), multiplicity, age of first diagnosis, and presence of metastatic disease (including tumor burden), other decisive factors for best clinical management of PCC/PGL include the underlying germline mutation. The above factors can impact the choice of different biomarkers and imaging modalities for PCC/PGL diagnosis, as well as screening for other neoplasms, staging, follow-up, and therapy options. This review provides a guide for practicing clinicians summarizing current management of PCC/PGL according to tumor size, location, age of first diagnosis, presence of metastases, and especially underlying mutations in the era of precision medicine.

Peptide Receptor Radionuclide Therapy as a Novel Treatment for Metastatic and Invasive Phaeochromocytoma and Paraganglioma

At present there is no clinical guideline or standardised protocol for the treatment of metastatic or invasive phaeochromocytoma and paraganglioma (collectively known as PPGL) due to the rarity of the disease and the lack of prospective studies or extended national databases. Prognosis is mainly determined by genetic predisposition, tumour burden, rate of disease progression, and location of metastases. For patients with progressive or symptomatic disease that is not amenable to surgery, there are various palliative treatment options available. These include localised therapies including radiotherapy, radiofrequency, or cryoablation, as well as liver-directed therapies for those patients with hepatic metastases (e.g., transarterial chemoembolisation) and systemic therapies including chemotherapy or molecular targeted therapies. There is currently intense research interest in the value of radionuclide therapy for neuroendocrine tumours, including phaeochromocytoma and paraganglioma, with either iodine-131 (131I)-radiolabelled metaiodobenzylguanidine or very recently peptide receptor radionuclide therapy (PRRT), and the most important contemporary clinical studies will be highlighted in this review. The studies to date suggest that PRRT may induce major clinical, biochemical, and radiological changes, with 177Lu-DOTATATE being most efficacious and presenting less toxicity than 90Y-DOTATATE. Newer combination therapies with combined radioisotopes, or combinations with chemotherapeutic agents, also look promising. Given the favourable efficacy, logistic, and safety profiles, we believe that PRRT will probably become the standard treatment for inoperable metastatic PPGL in the near future, but we await data from definitive randomised controlled trials to understand its role.

Metastatic Phaeochromocytoma: Spinning Towards More Promising Treatment Options

Phaeochromocytomas (PCC) and paragangliomas (PGL) are rare tumours arising from the chromaffin cells of the adrenal medulla (PCC) or the paraganglia located outside the adrenal gland (PGL). However, their incidence is likely to be underestimated; around 10% of all PCC/PGL are metastatic, with higher metastatic potential of PGLs compared to PCCs. If benign, surgery is the treatment of choice, but if metastatic, therapy is challenging. Here we review the currently existing therapy options for metastatic PCCs/PGLs including conventional chemotherapy (the original Averbuch scheme, but updated), radiopharmaceutical treatments (¹³¹I-MIBG, ⁹⁰Y- and ¹⁷⁷Lu-DOTATATE) and novel targeted therapies (anti-angiogenic tyrosine kinase inhibitors and mTORC1 inhibitors), emphasising future therapeutic approaches (HIF-2α and PARP inhibitors, temozolomide alone, metronomic temozolomide, somatostatin analogues) based on the oncogenic signalling pathways related to three different clusters comprising more than 20 well-characterised PCC/PGL susceptibility genes. We suggest that targeted combination therapies including repurposed agents may offer more effective future options worthy of exploration.

Targeted radionuclide therapy in combined-modality regimens

Targeted radionuclide therapy (TRT) is a branch of cancer medicine concerned with the use of radioisotopes, radiolabelled molecules, nanoparticles, or microparticles that either naturally accumulate in or are designed to target tumours. TRT combines the specificity of molecular and sometimes physical targeting with the potent cytotoxicity of ionising radiation. Targeting vectors for TRT include antibodies, antibody fragments, proteins, peptides, and small molecules. The diversity of available carrier molecules, together with the large panel of suitable radioisotopes with unique physicochemical properties, allows vector-radionuclide pairings to be matched to the molecular, pathological, and physical characteristics of a tumour. Some pairings are designed for dual therapeutic and diagnostic applications. Use of TRT is increasing with the adoption into practice of radium-223 dichloride for the treatment of bone metastases and with the ongoing clinical development of, among others, 177Lu-dodecanetetraacetic acid tyrosine-3-octreotate (DOTATATE) for the treatment of neuroendocrine tumours and 90Y-microspheres for the treatment of hepatic tumours. The increasing use of TRT raises the question of how best to integrate TRT into multimodality protocols. Achievements in this area and the future prospects of TRT are evaluated in this Review.

Molecular targeted therapies in adrenal, pituitary and parathyroid malignancies

Tumourigenesis is a relatively common event in endocrine tissues. Currently, specific guidelines have been developed for common malignant endocrine tumours, which also incorporate advances in molecular targeted therapies (MTT), as in thyroid cancer and in gastrointestinal neuroendocrine malignancies. However, there is little information regarding the role and efficacy of MTT in the relatively rare malignant endocrine tumours mainly involving the adrenal medulla, adrenal cortex, pituitary, and parathyroid glands. Due to the rarity of these tumours and the lack of prospective studies, current guidelines are mostly based on retrospective data derived from surgical, locoregional and ablative therapies, and studies with systemic chemotherapy. In addition, in many of these malignancies the prognosis remains poor with individual patients responding differently to currently available treatments, necessitating the development of new personalised therapeutic strategies. Recently, major advances in the molecular understanding of endocrine tumours based on genomic, epigenomic, and transcriptome analysis have emerged, resulting in new insights into their pathogenesis and molecular pathology. This in turn has led to the use of novel MTTs in increasing numbers of patients. In this review, we aim to present currently existing and evolving data using MTT in the treatment of adrenal, pituitary and malignant parathyroid tumours, and explore the current utility and effectiveness of such therapies and their future evolution.

Iodine-131-meta-iodobenzylguanidine therapy for patients with newly diagnosed high-risk neuroblastoma

BACKGROUND

Patients with newly diagnosed high-risk (HR) neuroblastoma (NBL) still have a poor outcome, despite multi-modality intensive therapy. This poor outcome necessitates the search for new therapies, such as treatment with ¹³¹I-meta-iodobenzylguanidine (¹³¹I-MIBG).

OBJECTIVES

To assess the efficacy and adverse effects of ¹³¹I-MIBG therapy in patients with newly diagnosed HR NBL.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library 2016, Issue 3), MEDLINE (PubMed) (1945 to 25 April 2016) and Embase (Ovid) (1980 to 25 April 2016). In addition, we handsearched reference lists of relevant articles and reviews. We also assessed the conference proceedings of the International Society for Paediatric Oncology, Advances in Neuroblastoma Research and the American Society of Clinical Oncology; all from 2010 up to and including 2015. We scanned the International Standard Randomized Controlled Trial Number (ISRCTN) Register (www.isrctn.com) and the National Institutes of Health Register for ongoing trials (www.clinicaltrials.gov) on 13 April 2016.

SELECTION CRITERIA

Randomised controlled trials (RCTs), controlled clinical trials (CCTs), non-randomised single-arm trials with historical controls and cohort studies examining the efficacy of ¹³¹I-MIBG therapy in 10 or more patients with newly diagnosed HR NBL.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, risk of bias assessment and data extraction.

MAIN RESULTS

We identified two eligible cohort studies including 60 children with newly diagnosed HR NBL. All studies had methodological limitations, with regard to both internal (risk of bias) and external validity. As the studies were not comparable with regard to prognostic factors and treatment (and often used different outcome definitions), pooling of results was not possible. In one study, the objective response rate (ORR) was 73% after surgery; the median overall survival was 15 months (95% confidence interval (CI) 7 to 23); five-year overall survival was 14.6%; median event-free survival was 10 months (95% CI 7 to 13); and five-year event-free survival was 12.2%. In the other study, the ORR was 56% after myeloablative therapy and autologous stem cell transplantation; 10-year overall survival was 6.25%; and event-free survival was not reported. With regard to short-term adverse effects, one study showed a prevalence of 2% (95% CI 0% to 13%; best-case scenario) for death due to myelosuppression. After the first cycle of ¹³¹I-MIBG therapy in one study, platelet toxicity occurred in 38% (95% CI 18% to 61%), neutrophil toxicity in 50% (95% CI 28% to 72%) and haemoglobin toxicity in 69% (95% CI 44% to 86%); after the second cycle this was 60% (95% CI 36% to 80%) for platelets and neutrophils and 53% (95% CI 30% to 75%) for haemoglobin. In one study, the prevalence of hepatic toxicity during or within four weeks after last the MIBG treatment was 0% (95% CI 0% to 9%; best-case scenario). Neither study reported cardiovascular toxicity and sialoadenitis. One study assessed long-term adverse events in some of the children: there was elevated plasma thyroid-stimulating hormone in 45% (95% CI 27% to 65%) of children; in all children, free T4 was within the age-related normal range (0%, 95% CI 0% to 15%). There were no secondary malignancies observed (0%, 95% CI 0% to 9%), but only five children survived more than four years.

AUTHORS' CONCLUSIONS

We identified no RCTs or CCTs comparing the effectiveness of treatment including ¹³¹I-MIBG therapy versus treatment not including ¹³¹I-MIBG therapy in patients with newly diagnosed HR NBL. We found two small observational studies including chilren. They had high risk of bias, and not all relevant outcome results were available. Based on the currently available evidence, we cannot make recommendations for the use of ¹³¹I-MIBG therapy in patients with newly diagnosed HR NBL in clinical practice. More high-quality research is needed.

I-131 Metaiodobenzylguanidine Therapy of Pheochromocytoma and Paraganglioma

Pheochromocytomas and paragangliomas are rare tumors arising from chromaffin cells. Available therapeutic modalities consist of chemotherapy, tyrosine kinase inhibitors, and I-131 metaiodobenzylguanidine (MIBG). I-131 MIBG is taken up via specific receptors and localizes into many but not all pheochromocytomas and paragangliomas. Because these tumors are rare, most therapy studies are retrospective presentations of clinical experience. Numerous retrospective studies and a few prospective studies have shown favorable responses in this disease, including symptomatic, biochemical, and objective responses. In this report, we review the experience of using I-131 MIBG therapy for targeting pheochromocytoma and paragangliomas.

Local recurrence of pheochromocytoma in multiple endocrine neoplasia type 2A: a diagnostic and therapeutic challenge

In a patient with multiple endocrine neoplasia type 2A (MEN2A), an inverted physiological ratio between urinary normetanephrines and metanephrines is an early marker of recurrence in epinephrine‐secreting pheochromocytoma, and 131I MIBG treatment appears to be a useful therapeutic option in order to avoid multiple invasive surgical procedures in pheochromocytomatosis.

Phaeochromocytoma and Paraganglioma

Phaeochromocytomas and paragangliomas are relatively uncommon tumours which may be manifest in many ways, specifically as sustained or paroxysmal hypertension, episodes of palpitations, sweating, headache and anxiety, or increasingly as an incidental finding. Recent studies have shown that an increasing number are due to germline mutations. This review concentrates on the diagnosis, biochemistry and treatment of these fascinating tumours.

Management of metastatic phaeochromocytoma and paraganglioma: use of iodine-131-meta-iodobenzylguanidine therapy in a tertiary referral centre

BACKGROUND

Phaeochromocytoma (phaeo) and paraganglioma (PGL) are rare conditions, which are malignant in up to 30%. Optimal treatment is controversial, but in patients with metastatic iodine-131-meta-iodobenzylguanidine ((123)I-MIBG) avid tumours, we offer (131)I-MIBG therapy. We summarize response rates, survival and safety in a cohort of such patients treated with (131)I-MIBG in our centre from 1986 to 2012.

DESIGN/METHODS

Retrospective analysis of the case notes of patients with metastatic phaeo/PGL who received (131)I-MIBG was undertaken; patients underwent clinical, biochemical and radiological evaluation within 6 months of each course of (131)I-MIBG therapy.

RESULTS

Twenty-two patients (9 males) were identified, 12 with metastatic PGL and 10 with phaeo. Overall median follow-up time after first dose of (131)I-MIBG was 53 months. In total, 68 doses of (131)I-MIBG were administered; average dose was 9967 MBq (269.4 mCi). After the first dose, >50% of patients demonstrated disease stability or partial response; progressive disease was seen in 9%. A subset of patients underwent repeated treatment with the majority demonstrating partial response or stable disease. No life-threatening adverse events were reported, but three patients developed hypothyroidism and two developed ovarian failure after repeated dosing. Five-year survival after original diagnosis was 68% and median (+inter quartile range) survival from date of diagnosis was 17 years (7.6-26.4) with no difference in survival according to diagnosis (P < 0.1).

CONCLUSIONS

(131)I-MIBG is well tolerated and associates with disease stabilization or improvement in the majority of patients with metastatic phaeo/PGL. However, stronger conclusions on treatment effectiveness are limited by lack of a directly comparable 'control group' as well as an alternative 'gold standard' treatment.

(131)I-MIBG therapy for malignant paraganglioma and phaeochromocytoma: systematic review and meta-analysis

BACKGROUND

(131)I-MIBG therapy can be used for palliative treatment of malignant paraganglioma and phaeochromocytoma. The main objective of this study was to perform a systematic review and meta-analysis assessing the effect of (131)I-MIBG therapy on tumour volume in patients with malignant paraganglioma/phaeochromocytoma.

METHODS

A literature search was performed in December 2012 to identify potentially relevant studies. Main outcomes were the pooled proportions of complete response, partial response and stable disease after radionuclide therapy. A meta-analysis was performed with an exact likelihood approach using a logistic regression with a random effect at the study level. Pooled proportions with 95% confidence intervals (CI) were reported.

RESULTS

Seventeen studies concerning a total of 243 patients with malignant paraganglioma/phaeochromocytoma were treated with (131)I-MIBG therapy. The mean follow-up ranged from 24 to 62 months. A meta-analysis of the effect of (131)I-MIBG therapy on tumour volume showed pooled proportions of complete response, partial response and stable disease of, respectively, 0·03 (95% CI: 0·06-0·15), 0·27 (95% CI: 0·19-0·37) and 0·52 (95% CI: 0·41-0·62) and for hormonal response 0·11 (95% CI: 0·05-0·22), 0·40 (95% CI: 0·28-0·53) and 0·21 (95% CI: 0·10-0·40), respectively. Separate analyses resulted in better results in hormonal response for patients with paraganglioma than for patients with phaeochromocytoma.

CONCLUSIONS

Data on the effects of (131)I-MIBG therapy on malignant paraganglioma/phaeochromocytoma suggest that stable disease concerning tumour volume and a partial hormonal response can be achieved in over 50% and 40% of patients, respectively, treated with (131)I-MIBG therapy. It cannot be ruled out that stable disease reflects not only the effect of MIBG therapy, but also (partly) the natural course of the disease.