Iodine-131-metaiodobenzylguanidine as initial induction therapy in stage 4 neuroblastoma patients over 1 year of age

Long-Term Risk of Subsequent Neoplasms in 5-Year Survivors of Childhood Neuroblastoma: A Dutch Childhood Cancer Survivor Study-LATER 3 Study

PURPOSE

Neuroblastoma survivors have an increased risk of developing subsequent malignant neoplasms (SMNs), but the risk of subsequent nonmalignant neoplasms (SNMNs) and risk factors are largely unknown. We analyzed the long-term risks and associated risk factors for developing SMNs and SNMNs in a well-characterized cohort of 5-year neuroblastoma survivors.

METHODS

We included 563 5-year neuroblastoma survivors from the Dutch Childhood Cancer Survivor Study (DCCSS)-LATER cohort, diagnosed during 1963-2014. Subsequent neoplasms were ascertained by linkages with the Netherlands Cancer Registry and the Dutch Nationwide Pathology Databank (Palga) and medical chart review. We calculated standardized incidence ratios (SIRs), absolute excess risk (AER), and cumulative incidences. Multivariable competing risk regression analysis was used to evaluate risk factors.

RESULTS

In total, 23 survivors developed an SMN and 60 an SNMN. After a median follow-up of 23.7 (range, 5.0-56.3) years, the risk of SMN was elevated compared with the general population (SIR, 4.0; 95% CI, 2.5 to 5.9; AER per 10,000 person-years, 15.1). The 30-year cumulative incidence was 3.4% (95% CI, 1.9 to 6.0) for SMNs and 10.4% (95% CI, 7.3 to 14.8) for SNMNs. Six survivors developed an SMN after iodine-metaiodobenzylguanidine (131IMIBG) treatment. Survivors treated with 131IMIBG had a higher risk of developing SMNs (subdistribution hazard ratio [SHR], 5.7; 95% CI, 1.8 to 17.8) and SNMNs (SHR, 2.6; 95% CI, 1.2 to 5.6) compared with survivors treated without 131IMIBG; results for SMNs were attenuated in high-risk patients only (SMNs SHR, 3.6; 95% CI, 0.9 to 15.3; SNMNs SHR, 1.5; 95% CI, 0.7 to 3.6).

CONCLUSION

Our results demonstrate that neuroblastoma survivors have an elevated risk of developing SMNs and a high risk of SNMNs. 131IMIBG may be a treatment-related risk factor for the development of SMN and SNMN, which needs further validation. Our results emphasize the need for awareness of subsequent neoplasms and the importance of follow-up care.

Advances in Radioligand Theranostics in Oncology

Theranostics with radioligands (radiotheranostics) has played a pivotal role in oncology. Radiotheranostics explores the molecular targets expressed on tumor cells to target them for imaging and therapy. In this way, radiotheranostics entails non-invasive demonstration of the in vivo expression of a molecular target of interest through imaging followed by the administration of therapeutic radioligand targeting the tumor-expressed molecular target. Therefore, radiotheranostics ensures that only patients with a high likelihood of response are treated with a particular radiotheranostic agent, ensuring the delivery of personalized care to cancer patients. Within the last decades, a couple of radiotheranostics agents, including Lutetium-177 DOTATATE (177Lu-DOTATATE) and Lutetium-177 prostate-specific membrane antigen (177Lu-PSMA), were shown to prolong the survival of cancer patients compared to the current standard of care leading to the regulatory approval of these agents for routine use in oncology care. This recent string of successful approvals has broadened the interest in the development of different radiotheranostic agents and their investigation for clinical translation. In this work, we present an updated appraisal of the literature, reviewing the recent advances in the use of established radiotheranostic agents such as radioiodine for differentiated thyroid carcinoma and Iodine-131-labeled meta-iodobenzylguanidine therapy of tumors of the sympathoadrenal axis as well as the recently approved 177Lu-DOTATATE and 177Lu-PSMA for differentiated neuroendocrine tumors and advanced prostate cancer, respectively. We also discuss the radiotheranostic agents that have been comprehensively characterized in preclinical studies and have shown some clinical evidence supporting their safety and efficacy, especially those targeting fibroblast activation protein (FAP) and chemokine receptor 4 (CXCR4) and those still being investigated in preclinical studies such as those targeting poly (ADP-ribose) polymerase (PARP) and epidermal growth factor receptor 2.

Timing and chemotherapy association for 131-I-MIBG treatment in high-risk neuroblastoma

Prognosis of high-risk neuroblastoma is dismal, despite intensive induction chemotherapy, surgery, high-dose chemotherapy, radiotherapy, and maintenance. Patients who do not achieve a complete metastatic response, with clearance of bone marrow and skeletal NB infiltration, after induction have a significantly lowersurvival rate. Thus, it's necessary to further intensifytreatment during this phase. 131-I-metaiodobenzylguanidine (131-I-MIBG) is a radioactive compound highly effective against neuroblastoma, with32% response rate in relapsed/resistant cases, and only hematological toxicity. 131-I-MIBG wasutilized at different doses in single or multiple administrations, before autologous transplant or combinedwith high-dose chemotherapy. Subsequently, it was added to consolidationin patients with advanced NB after induction, but an independent contribution against neuroblastoma and for myelotoxicity is difficult to determine. Despiteresults of a 2008 paper demonstratedefficacy and mild hematological toxicity of 131-I-MIBG at diagnosis, no center had included it with intensive chemotherapy in first-line treatment protocols. In our institution, at diagnosis, 131-I-MIBG was included in a 5-chemotherapy drug combination and administered on day-10, at doses up to 18.3 mCi/kg. Almost 87% of objective responses were observed 50 days from start with acceptable hematological toxicity. In this paper, we review the literature data regarding 131-I-MIBG treatment for neuroblastoma, and report on doses and combinations used, tumor responses and toxicity. 131-I-MIBG is very effective against neuroblastoma, in particular if given to patients at diagnosis and in combination with chemotherapy, and it should be included in all induction regimens to improve early responses rates and consequently long-term survival.

Current Status and Future Perspective on Molecular Imaging and Treatment of Neuroblastoma

Neuroblastoma is the most common extracranial solid tumor in children and arises from anywhere along the sympathetic nervous system. It is a highly heterogeneous disease with a wide range of prognosis, from spontaneous regression or maturing to highly aggressive. About half of pediatric neuroblastoma patients develop the metastatic disease at diagnosis, which carries a poor prognosis. Nuclear medicine plays a pivotal role in the diagnosis, staging, response assessment, and long-term follow-up of neuroblastoma. And it has also played a prominent role in the treatment of neuroblastoma. Because the structure of metaiodobenzylguanidine (MIBG) is similar to that of norepinephrine, 90% of neuroblastomas are MIBG-avid. 123I-MIBG whole-body scintigraphy is the standard nuclear imaging technique for neuroblastoma, usually in combination with SPECT/CT. However, approximately 10% of neuroblastomas are MIBG nonavid. PET imaging has many technical advantages over SPECT imaging, such as higher spatial and temporal resolution, higher sensitivity, superior quantitative capability, and whole-body tomographic imaging. In recent years, various tracers have been used for imaging neuroblastoma with PET. The importance of patient-specific targeted radionuclide therapy for neuroblastoma therapy has also increased. 131I-MIBG therapy is part of the front-line treatment for children with high-risk neuroblastoma. And peptide receptor radionuclide therapy with radionuclide-labeled somatostatin analogues has been successfully used in the therapy of neuroblastoma. Moreover, radioimmunoimaging has important applications in the diagnosis of neuroblastoma, and radioimmunotherapy may provide a novel treatment modality against neuroblastoma. This review discusses the use of current and novel radiopharmaceuticals in nuclear medicine imaging and therapy of neuroblastoma.

Current and upcoming radionuclide therapies in the direction of precision oncology: A narrative review

As new molecular tracers are identified to target specific receptors, tissue, and tumor types, opportunities arise for the development of both diagnostic tracers and their therapeutic counterparts, termed "theranostics." While diagnostic tracers utilize positron emitters or gamma-emitting radionuclides, their theranostic counterparts are typically bound to beta and alpha emitters, which can deliver specific and localized radiation to targets with minimal collateral damage to uninvolved surrounding structures. This is an exciting time in molecular imaging and therapy and a step towards personalized and precise medicine in which patients who were either without treatment options or not candidates for other therapies now have expanded options, with tangible data showing improved outcomes. This manuscript explores the current state of theranostics, providing background, treatment specifics, and toxicities, and discusses future potential trends.

Treatment outcomes among high-risk neuroblastoma patients receiving non-immunotherapy regimen: Multicenter study on behalf of the Thai Pediatric Oncology Group

BACKGROUND

Neuroblastoma is the most common extracranial malignant solid tumor during childhood. Despite intensified treatment, patients with high-risk neuroblastoma (HR-NBL) still carry a dismal prognosis. The Thai Pediatric Oncology Group (ThaiPOG) proposed the use of a multimodality treatment to improve outcomes of HR-NBL in non-immunotherapy settings.

METHODS

Patients with HR-NBL undergoing ThaiPOG protocols (ThaiPOG-NB-13HR or -18HR) between 2013 and 2019 were retrospectively reviewed. Patient demographic data, treatment modalities, outcomes, and prognostic factors were evaluated and analyzed.

RESULTS

A total of 183 patients with HR-NBL undergoing a topotecan containing induction regimen were enrolled in this study. During the consolidation phase (n = 169), 116 patients (68.6%) received conventional chemotherapy, while 53 patients (31.4%) underwent hematopoietic stem cell transplantation (HSCT). The 5-year overall survival (OS) and event-free survival (EFS) were 41.2% and 22.8%, respectively. Patients who underwent HSCT had more superior 5-year EFS (36%) than those who received chemotherapy (17.1%) (p = .041), although they both performed similarly in 5-year OS (48.7% vs. 39.8%, p = .17). The variation of survival outcomes was observed depending on the number of treatment modalities. HSCT combined with metaiodobenzylguanidine (MIBG) treatment and maintenance with 13-cis-retinoic acid (cis-RA) demonstrated a desirable 5-year OS and EFS of 65.6% and 58.3%, respectively. Poorly or undifferentiated tumor histology and cis-RA administration were independent factors associated with relapse and survival outcomes, respectively (p < .05).

CONCLUSION

A combination of HSCT and cis-RA successfully improved the outcomes of patients with HR-NBL in immunotherapy inaccessible settings.

High-Risk Neuroblastoma: Poor Outcomes Despite Aggressive Multimodal Therapy

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Neuroblastoma (NBL) is a highly malignant embryonal tumor that originates from the primordial neural crest cells. NBL is the most common tumor in infants and the most common extracranial solid tumor in children. The tumor is more commonly diagnosed in children of 1-4 years of age. NBL is characterized by enigmatic clinical behavior that ranges from spontaneous regression to an aggressive clinical course leading to frequent relapses and death. Based on the likelihood of progression and relapse, the International Neuroblastoma Risk Group classification system categorized NBL into very low risk, low risk, intermediate risk, and high risk (HR) groups. HR NBL is defined based on the patient's age (> 18 months), disease metastasis, tumor histology, and MYCN gene amplification. HR NBL is diagnosed in nearly 40% of patients, mainly those > 18 months of age, and is associated with aggressive clinical behavior. Treatment strategies involve the use of intensive chemotherapy (CTR), surgical resection, high dose CTR with hematopoietic stem cell support, radiotherapy, biotherapy, and immunotherapy with Anti-ganglioside 2 monoclonal antibodies. Although HR NBL is now better characterized and aggressive multimodal therapy is applied, the outcomes of treatment are still poor, with overall survival and event-free survival of approximately 40% and 30% at 3-years, respectively. The short and long-term side effects of therapy are tremendous. HR NBL carries a high mortality rate accounting for nearly 15% of pediatric cancer deaths. However, most mortalities are attributed to the high frequency of disease relapse (50%) and disease reactiveness to therapy (20%). Newer treatment strategies are therefore urgently needed. Recent discoveries in the field of biology and molecular genetics of NBL have led to the identification of several targets that can improve the treatment results. In this review, we discuss the different aspects of the epidemiology, biology, clinical presentations, diagnosis, and treatment of HR NBL, in addition to the recent developments in the management of the disease.

The efficacy and safety of Iodine-131-metaiodobenzylguanidine therapy in patients with neuroblastoma: a meta-analysis

Objective

Neuroblastoma is a common extracranial solid tumor of childhood. Recently, multiple treatments have been practiced including Iodine-131-metaiodobenzylguanidine radiation (¹³¹I-MIBG) therapy. However, the outcomes of efficacy and safety vary greatly among different studies. The aim of this meta-analysis is to evaluate the efficacy and safety of ¹³¹I-MIBG in the treatment of neuroblastoma and to provide evidence and hints for clinical decision-making.

Methods

Medline, EMBASE database and the Cochrane Library were searched for relevant studies. Eligible studies utilizing ¹³¹I-MIBG in the treatment of neuroblastoma were included. The pooled outcomes (response rates, adverse events rates, survival rates) were calculated using either a random-effects model or a fixed-effects model considering of the heterogeneity.

Results

A total of 26 clinical trials including 883 patients were analyzed. The pooled rates of objective response, stable disease, progressive disease, and minor response of ¹³¹I-MIBG monotherapy were 39%, 31%, 22% and 15%, respectively. The pooled objective response rate of ¹³¹I-MIBG in combination with other therapies was 28%. The pooled 1-year survival and 5-year survival rates were 64% and 32%. The pooled occurrence rates of thrombocytopenia and neutropenia in MIBG monotherapy studies were 53% and 58%. In the studies of ¹³¹I-MIBG combined with other therapies, the pooled occurrence rates of thrombocytopenia and neutropenia were 79% and 78%.

Conclusion

¹³¹I-MIBG treatment alone or in combination of other therapies is effective on clinical outcomes in the treatment of neuroblastoma, individualized ¹³¹I-MIBG is recommended on a clinical basis.

Radiotheranostics - Precision Medicine in Nuclear Medicine and Molecular Imaging

'See what you treat and treat what you see, at a molecular level', could be the motto of theranostics. The concept implies diagnosis (imaging) and treatment of cells (usually cancer) using the same molecule, thus guaranteeing a targeted cytotoxic approach of the imaged tumor cells while sparing healthy tissues. As the brilliant late Sam Gambhir would say, the imaging agent acts like a 'molecular spy' and reveals where the tumoral cells are located and the extent of disease burden (diagnosis). For treatment, the same 'molecular spy' docks to the same tumor cells, this time delivering cytotoxic doses of radiation (treatment). This duality represents the concept of a 'theranostic pair', which follows the scope and fundamental principles of targeted precision and personalized medicine. Although the term theranostic was noted in medical literature in the early 2000s, the principle is not at all new to nuclear medicine. The first example of theranostic dates back to 1941 when Dr. Saul Hertz first applied radioiodine for radionuclide treatment of thyroid cells in patients with hyperthyroidism. Ever since, theranostics has been an integral element of nuclear medicine and molecular imaging. The more we understand tumor biology and molecular pathology of carcinogenesis, including specific mutations and receptor expression profiles, the more specific these 'molecular spies' can be developed for diagnostic molecular imaging and subsequent radionuclide targeted therapy (radiotheranostics). The appropriate selection of the diagnostic and therapeutic radionuclide for the 'theranostic pair' is critical and takes into account not only the type of cytotoxic radiation emission, but also the linear energy transfer (LET), and the physical half-lives. Advances in radiochemistry and radiopharmacy with new radiolabeling techniques and chelators are revolutionizing the field. The landscape of cytotoxic systemic radionuclide treatments has dramatically expanded through the past decades thanks to all these advancements. This article discusses present and promising future theranostic applications for various types of diseases such as thyroid disorders, neuroendocrine tumors (NET), pediatric malignancies, and prostate cancer (PC), and provides an outlook for future perspectives.

Refractory Stage M Ganglioneuroblastoma With Bone Metastases and a Favorable, Chronic Course of Disease: Description of a Patient Cohort

Refractory stage M neuroblastoma (NB) is associated with a poor prognosis and a progressive course of disease. Here, we describe a unique group of patients with a discrepant clinical course. Seven histologically confirmed ganglioneuroblastoma (GNB) (n=6) and differentiating NB (n=1) patients were identified who were diagnosed with stage M disease based on iodine-123-metaiodobenzylguanidine avid bone metastases. Six patients started on high-risk treatment, without tumor response (stable disease). Treatment was discontinued before the start of consolidation treatment because of refractory response in all patients. Unexpectedly, after cessation of treatment no progression of disease occurred. In 2 patients, the primary tumors expanded (>25%) very slowly during 1.5 and 3 years, and remained stable thereafter. Metabolically, a slow decrease of urinary homovanillic acid and vanillylmandelic acid levels and iodine-123-metaiodobenzylguanidine avidity was observed. All patients are alive with presence of metastatic disease after a median follow-up of 17 years (range: 6.7 to 27 y). Interestingly, at diagnosis, 6 patients were asymptomatic, 6 patients had GNB morphology, and 5 patients had meningeal metastases. These are all features seen in only a small minority of stage M patients. This GNB entity illustrates the clinical heterogeneity of neuroblastic tumors and can be used to further study the developmental origin of different NB subtypes.

A safety and feasibility trial of 131 I-MIBG in newly diagnosed high-risk neuroblastoma: A Children's Oncology Group study

INTRODUCTION

¹³¹ I-meta-iodobenzylguanidine (¹³¹ I-MIBG) is effective in relapsed neuroblastoma. The Children's Oncology Group (COG) conducted a pilot study (NCT01175356) to assess tolerability and feasibility of induction chemotherapy followed by ¹³¹ I^- MIBG therapy and myeloablative busulfan/melphalan (Bu/Mel) in patients with newly diagnosed high-risk neuroblastoma.

METHODS

Patients with MIBG-avid high-risk neuroblastoma were eligible. After the first two patients to receive protocol therapy developed severe sinusoidal obstruction syndrome (SOS), the trial was re-designed to include an ¹³¹ I-MIBG dose escalation (12, 15, and 18 mCi/kg), with a required 10-week gap before Bu/Mel administration. Patients who completed induction chemotherapy were evaluable for assessment of ¹³¹ I-MIBG feasibility; those who completed ¹³¹ I-MIBG therapy were evaluable for assessment of ¹³¹ I-MIBG + Bu/Mel feasibility.

RESULTS

Fifty-nine of 68 patients (86.8%) who completed induction chemotherapy received ¹³¹ I-MIBG. Thirty-seven of 45 patients (82.2%) evaluable for ¹³¹ I-MIBG + Bu/Mel received this combination. Among those who received ¹³¹ I-MIBG after revision of the study design, one patient per dose level developed severe SOS. Rates of moderate to severe SOS at 12, 15, and 18 mCi/kg were 33.3%, 23.5%, and 25.0%, respectively. There was one toxic death. The ¹³¹ I-MIBG and ¹³¹ I-MIBG+Bu/Mel feasibility rates at the 15 mCi/kg dose level designated for further study were 96.7% (95% CI: 83.3%-99.4%) and 81.0% (95% CI: 60.0%-92.3%).

CONCLUSION

This pilot trial demonstrated feasibility and tolerability of administering ¹³¹ I-MIBG followed by myeloablative therapy with Bu/Mel to newly diagnosed children with high-risk neuroblastoma in a cooperative group setting, laying the groundwork for a cooperative randomized trial (NCT03126916) testing the addition of ¹³¹ I-MIBG during induction therapy.

Thrombocytopenia after meta-iodobenzylguanidine (MIBG) therapy in neuroblastoma patients may be caused by selective MIBG uptake via the serotonin transporter located on megakaryocytes

Background

The therapeutic use of [¹³¹I]meta-iodobenzylguanidine ([¹³¹I]MIBG) is often accompanied by hematological toxicity, primarily consisting of severe and persistent thrombocytopenia. We hypothesize that this is caused by selective uptake of MIBG via the serotonin transporter (SERT) located on platelets and megakaryocytes. In this study, we have investigated whether in vitro cultured human megakaryocytes are capable of selective plasma membrane transport of MIBG and whether pharmacological intervention with selective serotonin reuptake inhibitors (SSRIs) may prevent this radiotoxic MIBG uptake.

Methods

Peripheral blood CD34⁺ cells were differentiated to human megakaryocytic cells using a standardized culture protocol. Prior to [³H]serotonin and [¹²⁵I]MIBG uptake experiments, the differentiation status of megakaryocyte cultures was assessed by flow cytometry. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to assess SERT and NET (norepinephrine transporter) mRNA expression. On day 10 of differentiation, [³H]serotonin and [¹²⁵I]MIBG uptake assays were conducted. Part of the samples were co-incubated with the SSRI citalopram to assess SERT-specific uptake. HEK293 cells transfected with SERT, NET, and empty vector served as controls.

Results

In vitro cultured human megakaryocytes are capable of selective plasma membrane transport of MIBG. After 10 days of differentiation, megakaryocytic cell culture batches from three different hematopoietic stem and progenitor cell donors showed on average 9.2 ± 2.4 nmol of MIBG uptake per milligram protein per hour after incubation with 10^–7 M MIBG (range: 6.6 ± 1.0 to 11.2 ± 1.0 nmol/mg/h). Co-incubation with the SSRI citalopram led to a significant reduction (30.1%—41.5%) in MIBG uptake, implying SERT-specific uptake of MIBG. A strong correlation between the number of mature megakaryocytes and SERT-specific MIBG uptake was observed.

Conclusion

Our study demonstrates that human megakaryocytes cultured in vitro are capable of MIBG uptake. Moreover, the SSRI citalopram selectively inhibits MIBG uptake via the serotonin transporter. The concomitant administration of citalopram to neuroblastoma patients during [¹³¹I]MIBG therapy might be a promising strategy to prevent the onset of thrombocytopenia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-021-00823-5.

Advances in pharmacotherapy for neuroblastoma

INTRODUCTION

Neuroblastoma is the most prevalent cancer type diagnosed within the first year after birth and accounts for 15% of deaths from pediatric cancer. Despite the improvements in survival rates of patients with neuroblastoma, the incidence of the disease has increased over the last decade. Neuroblastoma tumor cells harbor a vast range of variable and heterogeneous histochemical and genetic alterations which calls for the need to administer individualized and targeted therapies to induce tumor regression in each patient.

AREAS COVERED

This paper provides reviews the recent clinical trials which used chemotherapeutic and/or targeted agents as either monotherapies or in combination to improve the response rate in patients with neuroblastoma, and especially high-risk neuroblastoma. It also reviews some of the prominent preclinical studies which can provide the rationale for future clinical trials.

EXPERT OPINION

Although some distinguished advances in pharmacotherapy have been made to improve the survival rate and reduce adverse events in patients with neuroblastoma, a more comprehensive understanding of the mechanisms of tumorigenesis, resistance to therapies or relapse, identifying biomarkers of response to each specific drug, and developing predictive preclinical models of the tumor can lead to further breakthroughs in the treatment of neuroblastoma.

Theranostics in Neuroblastoma

Theranostics combines diagnosis and targeted therapy, achieved by the use of the same or similar molecules labeled with different radiopharmaceuticals or identical with different dosages. One of the best examples is the use of metaiodobenzylguanidine (MIBG). In the management of neuroblastoma-the most common extracranial solid tumor in children. MIBG has utility not only for diagnosis, risk-stratification, and response monitoring but also for cancer therapy, particularly in the setting of relapsed/refractory disease. Improved techniques and new emerging radiopharmaceuticals likely will strengthen the role of nuclear medicine in the management of neuroblastoma.

Upfront consolidation treatment with 131I-mIbG followed by myeloablative chemotherapy and hematopoietic stem cell transplantation in high-risk neuroblastoma

Importance

¹³¹I‐metaiodobenzylguanidine (¹³¹I‐mIBG) has a significant targeted antitumor effect for neuroblastoma. However, currently there is a paucity of data for the use of ¹³¹I‐mIBG as a “front‐line” therapeutic agent in those patients with newly diagnosed high‐risk neuroblastoma as part of the conditioning regimen for myeloablative chemotherapy (MAC).

Objective

To evaluate the feasibility of upfront consolidation treatment with ¹³¹I‐mIBG plus MAC and hematopoietic stem cell transplantation (HSCT) in high‐risk neuroblastoma patients.

Methods

A retrospective, single‐center study was conducted from 2003–2019 on newly diagnosed high‐risk neuroblastoma patients without progressive disease (PD) after the completion of induction therapy. They received ¹³¹I‐mIBG infusion and MAC followed by HSCT.

Results

A total of 24 high‐risk neuroblastoma patients were enrolled with a median age of 3.0 years at diagnosis. After receiving this sequential consolidation treatment, 3 of 13 patients who were in partial response (PR) before ¹³¹I‐mIBG treatment achieved either complete response (CR) (n = 1) or very good partial response (VGPR) (n = 2) after HSCT. With a median follow‐up duration of 13.0 months after ¹³¹I‐mIBG therapy, the 5‐year event‐free survival and overall survival rates estimated were 29% and 38% for the entire cohort, and 53% and 67% for the patients who were in CR/VGPR at the time of ¹³¹I‐mIBG treatment.

Interpretation

Upfront consolidation treatment with ¹³¹I‐mIBG plus MAC and HSCT is feasible and tolerable in high‐risk neuroblastoma patients, however the survival benefit of this ¹³¹I‐mIBG regimen is only observed in the patients who were in CR/VGPR at the time of ¹³¹I‐mIBG treatment.

Theranostic approaches in nuclear medicine: current status and future prospects

Introduction: Theranostics is an emerging field in which diagnosis and specific targeted therapy are combined to achieve a personalized treatment approach to the patient. In nuclear medicine clinical practice, theranostics is often performed utilizing the same molecule labeled with two different radionuclides, one radionuclide for imaging and another for therapy.Areas covered: The authors review the clinical applications of different radiopharmaceuticals in the field of interest, including the well-established use of radioactive iodine in differentiated thyroid cancer, radiolabeled metaiodobenzylguanidine (MIBG) in neuroblastoma and the clinical impact of peptide radionuclide receptorial therapy (PRRT) in the management of neuroendocrine tumors. Furthermore, the more cutting-edge and recently introduced theranostic approaches will be reviewed, such as the radioligand therapy with ¹⁷⁷Lu-prostate specific membrane antigen (PSMA) and targeted alpha therapy in castration-resistant prostate cancer. Finally, the main applications of PET for the imaging of biomarkers suitable for the non-radionuclide targeted therapy will be covered.Expert opinion: Theranostics is envisaging a revolutionary clinical approach which is deeply connected with the concept of personalized medicine and ruled by a 'patient-centered' vision. In this perspective, the theranostic applications will need well-trained specialists, capable to manage not only the technological aspects of the discipline, but also to deal with the more innovative oncological therapies in a multidisciplinary setting.

Bench-to-Bedside Theranostics in Nuclear Medicine

The optimum selection of the appropriate radiolabelled probe for the right target and the right patient is the foundation of theranostics in personalised medicine. In nuclear medicine, this process is realised through the appropriate choice of radiopharmaceuticals based on molecular biomarkers regarding molecular imaging. Theranostics is developing a strategy that can be used to implement accepted tools for individual molecular targeting, including diagnostics, and advances in genomic molecular knowledge, which has led to identifying theranostics biomaterials that have the potency to diagnose and treat malignancies. Today, numerous studies have reported on the discovery and execution of these radiotracers in personalised medicine. In this review, we presented our point of view of the most important theranostics agents that can be used to treat several types of malignancies. Molecular targeted radionuclide treatment methods based on theranostics are excellent paradigms of the relationship between molecular imaging and therapy that has been used to provide individualised or personalised patient care. Toward that end, a precise planned prospective examination of theranostics must be done to compare this approach to more standard therapies.

MIBG in neuroblastoma diagnosis and treatment

Neuroblastoma is a heterogenous disease, with solid tumors arising in the adrenal gland or paraspinal regions in young children. Neuroblastoma is unique, with varied presentation and prognosis based on primary location and tumor stage. Tumor behavior and response to treatment ranges from spontaneous regression to disseminated, lethal disease depending on the individual biology of a patient's tumor. Stratification of the disease has changed, with patients now placed in low, intermediate, and high-risk categories depending on age, stage, and tumor biology. Long-term survival for the high-risk subset of patients with metastatic disease is <40% despite aggressive multimodal therapy. Derived from sympathoadrenal cells of the adrenal medulla and sympathetic nervous system, both malignant neuroblastoma and differentiated tumors have specialized norepinephrine transporter (NET) receptors which are naturally occurring in the sympathetic nervous system throughout the body. Metaiodobenzylguanidine (MIBG) is a norepinephrine analog that undergoes active uptake by NET receptors resulting in accumulation in neuroblastoma as well as tissues normally expressing the NET receptor. When radioiodine labeled, MIBG can be used for both diagnosis and treatment. This article describes the history of MIBG use in neuroblastoma, including its utility as an imaging modality for diagnosis as well as the varied ways in which is it included in the multimodal treatment algorithm.

Peripheral Stem Cell Apheresis is Feasible Post 131Iodine-Metaiodobenzylguanidine-Therapy in High-Risk Neuroblastoma, but Results in Delayed Platelet Reconstitution

PURPOSE

Targeted radiotherapy with ¹³¹iodine-meta-iodobenzylguanidine (¹³¹I-MIBG) is effective for neuroblastoma (NBL), although optimal scheduling during high-risk (HR) treatment is being investigated. We aimed to evaluate the feasibility of stem cell apheresis and study hematologic reconstitution after autologous stem cell transplantation (ASCT) in patients with HR-NBL treated with upfront ¹³¹I-MIBG-therapy.

EXPERIMENTAL DESIGN

In two prospective multicenter cohort studies, newly diagnosed patients with HR-NBL were treated with two courses of ¹³¹I-MIBG-therapy, followed by an HR-induction protocol. Hematopoietic stem and progenitor cell (e.g., CD34⁺ cell) harvest yield, required number of apheresis sessions, and time to neutrophil (>0.5 × 10⁹/L) and platelet (>20 × 10⁹/L) reconstitution after ASCT were analyzed and compared with "chemotherapy-only"-treated patients. Moreover, harvested CD34⁺ cells were functionally (viability and clonogenic capacity) and phenotypically (CD33, CD41, and CD62L) tested before cryopreservation (n = 44) and/or after thawing (n = 19).

RESULTS

Thirty-eight patients (47%) were treated with ¹³¹I-MIBG-therapy, 43 (53%) only with chemotherapy. Median cumulative ¹³¹I-MIBG dose/kg was 0.81 GBq (22.1 mCi). Median CD34⁺ cell harvest yield and apheresis days were comparable in both groups. Post ASCT, neutrophil recovery was similar (11 days vs. 10 days), whereas platelet recovery was delayed in ¹³¹I-MIBG- compared with chemotherapy-only-treated patients (29 days vs. 15 days, P = 0.037). Testing of harvested CD34⁺ cells revealed a reduced post-thaw viability in the ¹³¹I-MIBG-group. Moreover, the viable CD34⁺ population contained fewer cells expressing CD62L (L-selectin), a marker associated with rapid platelet recovery.

CONCLUSIONS

Harvesting of CD34⁺ cells is feasible after ¹³¹I-MIBG. Platelet recovery after ASCT was delayed in ¹³¹I-MIBG-treated patients, possibly due to reinfusion of less viable and CD62L-expressing CD34⁺ cells, but without clinical complications. We provide evidence that peripheral stem cell apheresis is feasible after upfront ¹³¹I-MIBG-therapy in newly diagnosed patients with NBL. However, as the harvest of ¹³¹I-MIBG-treated patients contained lower viable CD34⁺ cell counts after thawing and platelet recovery after reinfusion was delayed, administration of ¹³¹I-MIBG after apheresis is preferred.

Neuroblastoma

Neuroblastoma is one of the most common solid tumors in children and has a diverse clinical behavior that largely depends on the tumor biology. Neuroblastoma exhibits unique features, such as early age of onset, high frequency of metastatic disease at diagnosis in patients over 1 year of age and the tendency for spontaneous regression of tumors in infants. The high-risk tumors frequently have amplification of the MYCN oncogene as well as segmental chromosome alterations with poor survival. Recent advanced genomic sequencing technology has revealed that mutation of ALK, which is present in ~10% of primary tumors, often causes familial neuroblastoma with germline mutation. However, the frequency of gene mutations is relatively small and other aberrations, such as epigenetic abnormalities, have also been proposed. The risk-stratified therapy was introduced by the Japan Neuroblastoma Study Group (JNBSG), which is now moving to the Neuroblastoma Committee of Japan Children's Cancer Group (JCCG). Several clinical studies have facilitated the reduction of therapy for children with low-risk neuroblastoma disease and the significant improvement of cure rates for patients with intermediate-risk as well as high-risk disease. Therapy for patients with high-risk disease includes intensive induction chemotherapy and myeloablative chemotherapy, followed by the treatment of minimal residual disease using differentiation therapy and immunotherapy. The JCCG aims for better cures and long-term quality of life for children with cancer by facilitating new approaches targeting novel driver proteins, genetic pathways and the tumor microenvironment.

Pediatric oncology as a Learning Health System: Ethical implications for best available treatment protocols

INTRODUCTION

Pediatric oncology is often considered as a field in which research and care are highly integrated. We believe that this integration can be seen as a so-called Learning Health System, a system in which research is considered an important means to continuously improve the practice of care. In order to substantiate our assumption of pediatric oncology as an LHS, we will analyze so-called "best available treatment protocols." These protocols always contain research elements, even if themain goal of these protocols is to treat children diagnosed with cancer.

METHODS

We will analyze the implications for ethical review and informed consent if these protocols had to function as exponents of pediatric oncology an LHS.

RESULTS

An analysis of best available treatment protocols teaches us how these protocols integrate care and research and how these protocols can be seen as exponents of a system where care and research need no longer be sharply distinct practices.

DISCUSSION

Further intervention in the field of pediatric oncology is essential to also meet the requirements for an ethically responsible LHS.

CONCLUSION

Best available treatment protocols, which combine research and care, can be seen as examples of pediatric oncology as an LHS. However, in order to prevent that research elements in these protocols will be overlooked, we will have to find new ways to accommodate for the oversight of these protocols, such as multifaceted review and risk-adapted approaches. Moreover, informed consent process must be changed in order for patients to understand how care and research are integrated in these protocols.

3-Methoxytyramine: An independent prognostic biomarker that associates with high-risk disease and poor clinical outcome in neuroblastoma patients

INTRODUCTION

Prognosis of neuroblastoma patients is very diverse, indicating the need for more accurate prognostic parameters. The excretion of catecholamine metabolites by most neuroblastomas is used for diagnostic purposes, but their correlation with prognosis has hardly been investigated. Therefore, we performed an in-depth analysis of a panel of elevated urinary catecholamine metabolites at diagnosis and their correlation with prognosis.

PATIENTS AND METHODS

Retrospective study of eight urinary catecholamine metabolites in a test (n = 96) and validation (n = 205) cohort of patients with neuroblastoma (all stages) at diagnosis.

RESULTS

Multivariate analyses, including risk factors such as stage and MYCN amplification, revealed that 3-methoxytyramine (3MT) was an independent risk factor for event-free survival (EFS) and overall survival (OS). Furthermore, only 3MT appeared to be an independent risk factor for both EFS and OS in high-risk patients, which was independent of modern high-risk therapy and immunotherapy. Among high-risk patients, those with elevated 3MT and older than 18 months had an extremely poor prognosis compared to patients with non-elevated 3MT and younger than 18 months (5-year EFS of 14.3% ± 4% and 66.7% ± 18%, respectively, p = 0.001; 5-year OS of 21.8% ± 5% and 87.5% ± 12%, respectively, p < 0.001).

CONCLUSIONS

Elevated 3MT at diagnosis was associated with high-risk disease and poor prognosis. For high-risk patients, elevated 3MT at diagnosis was the only significant risk factor for EFS and OS. 3MT was also able to identify subgroups of high-risk patients with favourable and extremely poor prognosis.

Norepinephrine Transporter as a Target for Imaging and Therapy

The norepinephrine transporter (NET) is essential for norepinephrine uptake at the synaptic terminals and adrenal chromaffin cells. In neuroendocrine tumors, NET can be targeted for imaging as well as therapy. One of the most widely used theranostic agents targeting NET is metaiodobenzylguanidine (MIBG), a guanethidine analog of norepinephrine. ¹²³I/¹³¹I-MIBG theranostics have been applied in the clinical evaluation and management of neuroendocrine tumors, especially in neuroblastoma, paraganglioma, and pheochromocytoma. ¹²³I-MIBG imaging is a mainstay in the evaluation of neuroblastoma, and ¹³¹I-MIBG has been used for the treatment of relapsed high-risk neuroblastoma for several years, however, the outcome remains suboptimal. ¹³¹I-MIBG has essentially been only palliative in paraganglioma/pheochromocytoma patients. Various techniques of improving therapeutic outcomes, such as dosimetric estimations, high-dose therapies, multiple fractionated administration and combination therapy with radiation sensitizers, chemotherapy, and other radionuclide therapies, are being evaluated. PET tracers targeting NET appear promising and may be more convenient options for the imaging and assessment after treatment. Here, we present an overview of NET as a target for theranostics; review its current role in some neuroendocrine tumors, such as neuroblastoma, paraganglioma/pheochromocytoma, and carcinoids; and discuss approaches to improving targeting and theranostic outcomes.

Retinoic acid postconsolidation therapy for high-risk neuroblastoma patients treated with autologous haematopoietic stem cell transplantation

BACKGROUND

Neuroblastoma is a rare malignant disease and mainly affects infants and very young children. The tumours mainly develop in the adrenal medullary tissue, with an abdominal mass as the most common presentation. About 50% of patients have metastatic disease at diagnosis. The high-risk group is characterised by metastasis and other features that increase the risk of an adverse outcome. High-risk patients have a five-year event-free survival of less than 50%. Retinoic acid has been shown to inhibit growth of human neuroblastoma cells and has been considered as a potential candidate for improving the outcome of patients with high-risk neuroblastoma. This review is an update of a previously published Cochrane Review.

OBJECTIVES

To evaluate the efficacy and safety of additional retinoic acid as part of a postconsolidation therapy after high-dose chemotherapy (HDCT) followed by autologous haematopoietic stem cell transplantation (HSCT), compared to placebo retinoic acid or to no additional retinoic acid in people with high-risk neuroblastoma (as defined by the International Neuroblastoma Risk Group (INRG) classification system).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library (2016, Issue 11), MEDLINE in PubMed (1946 to 24 November 2016), and Embase in Ovid (1947 to 24 November 2016). Further searches included trial registries (on 22 December 2016), conference proceedings (on 23 March 2017) and reference lists of recent reviews and relevant studies. We did not apply limits by publication year or languages.

SELECTION CRITERIA

Randomised controlled trials (RCTs) evaluating additional retinoic acid after HDCT followed by HSCT for people with high-risk neuroblastoma compared to placebo retinoic acid or to no additional retinoic acid. Primary outcomes were overall survival and treatment-related mortality. Secondary outcomes were progression-free survival, event-free survival, early toxicity, late toxicity, and health-related quality of life.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

The update search did not identify any additional studies. We identified one RCT that included people with high-risk neuroblastoma who received HDCT followed by autologous HSCT (N = 98) after a first random allocation and who received retinoic acid (13-cis-retinoic acid; N = 50) or no further therapy (N = 48) after a second random allocation. These 98 participants had no progressive disease after HDCT followed by autologous HSCT. There was no clear evidence of difference between the treatment groups either in overall survival (hazard ratio (HR) 0.87, 95% confidence interval (CI) 0.46 to 1.63; one trial; P = 0.66) or in event-free survival (HR 0.86, 95% CI 0.50 to 1.49; one trial; P = 0.59). We calculated the HR values using the complete follow-up period of the trial. The study also reported overall survival estimates at a fixed point in time. At the time point of five years, the survival estimate was reported to be 59% for the retinoic acid group and 41% for the no-further-therapy group (P value not reported). We did not identify results for treatment-related mortality, progression-free survival, early or late toxicity, or health-related quality of life. We could not rule out the possible presence of selection bias, performance bias, attrition bias, and other bias. We judged the evidence to be of low quality for overall survival and event-free survival, downgraded because of study limitations and imprecision.

AUTHORS' CONCLUSIONS

We identified one RCT that evaluated additional retinoic acid as part of a postconsolidation therapy after HDCT followed by autologous HSCT versus no further therapy in people with high-risk neuroblastoma. There was no clear evidence of a difference in overall survival and event-free survival between the treatment alternatives. This could be the result of low power. Information on other outcomes was not available. This trial was performed in the 1990s, since when many changes in treatment and risk classification have occurred. Based on the currently available evidence, we are therefore uncertain about the effects of retinoic acid in people with high-risk neuroblastoma. More research is needed for a definitive conclusion.

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.

Emerging and investigational therapies for neuroblastoma

INTRODUCTION

Treatment for children with clinically aggressive, high-risk neuroblastoma remains challenging. Less than 50% of patients with high-risk neuroblastoma will survive long-term with current therapies, and survivors are at risk for serious treatment-related late toxicities. Here, we review new and evolving treatments that may ultimately improve outcome for children with high-risk neuroblastoma with decreased potential for late adverse events.

AREAS COVERED

New strategies for treating high-risk neuroblastoma are reviewed including: radiotherapy, targeted cytotoxics, biologics, immunotherapy, and molecularly targeted agents. Recently completed and ongoing neuroblastoma clinical trials testing these novel treatments are highlighted. In addition, we discuss ongoing clinical trials designed to evaluate precision medicine approaches that target actionable somatic mutations and oncogenic cellular pathways.

EXPERT OPINION

Advances in genomic medicine and molecular biology have led to the development of early phase studies testing biologically rational therapies targeting aberrantly activated cellular pathways. Because many of these drugs have a wider therapeutic index than standard chemotherapeutic agents, these treatments may be more effective and less toxic than current strategies. However, to effectively integrate these targeted strategies, robust predictive biomarkers must be developed that will identify patients who will benefit from these approaches and rapidly match treatments to patients at diagnosis.

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.

Clinical research on rare diseases of children: neuroblastoma

PURPOSE

Early access to new treatment options should not preclude accurate research planning, especially for rare diseases and fragile populations. Taking neuroblastoma as a model case, we analyzed the rationale supporting the search for future therapeutic strategies in the light of preclinical and clinical evidence.

METHODS

We reviewed ongoing randomized trials of pharmacological interventions for the treatment of neuroblastoma retrieved by searching ClinicalTrials.gov and the European Union Clinical Trials Registry (last update March 2016).

RESULTS

Our search identified four randomized clinical trial reports. We found poor evidence from preclinical and early clinical research supporting their rationale. Their methodology was questionable too.

CONCLUSIONS

The urgency to cover unmet needs in difficult clinical settings like rare diseases, particularly those involving fragile populations, cannot justify disorderly research approaches. Under these circumstances, clinical questions should be properly identified and addressed to protect patients and avoid wasteful research.

Neuroblastoma: MIBG Imaging and New Tracers

Neuroblastoma is an embryonic tumor of the peripheral sympathetic nervous system, and is metastatic or otherwise high risk for relapse in nearly 50% of cases, with a long-term survival of <40%. Therefore, exact staging with radiological and nuclear medicine imaging methods is crucial for finding the adequate therapeutic choice. The tumor cells express the norepinephrine transporter, which makes metaiodobenzylguanidine (MIBG), an analogue of norepinephrine, an ideal tumor-specific agent for imaging. On the contrary, MIBG imaging has several disadvantages such as limited spatial resolution, limited sensitivity in small lesions, need for two or even more acquisition sessions, and a delay between the start of the examination and result. Most of these limitations can be overcome with positron emission tomography (PET) using different radiotracers. Furthermore, for operative or biopsy planning, a combination with morphological imaging methods is indispensable. This article would discuss the therapeutic strategy for primary and follow-up diagnosis in neuroblastoma using MIBG scintigraphy and different new PET tracers as well as multimodality imaging.

MIBG in Neuroblastoma Diagnostic Imaging and Therapy

Neuroblastoma is a common malignancy observed in infants and young children. It has a varied prognosis, ranging from spontaneous regression to aggressive metastatic tumors with fatal outcomes despite multimodality therapy. Patients are divided into risk groups on the basis of age, stage, and biologic tumor factors. Multiple clinical and imaging tests are needed for accurate patient assessment. Iodine 123 ((123)I) metaiodobenzylguanidine (MIBG) is the first-line functional imaging agent used in neuroblastoma imaging. MIBG uptake is seen in 90% of neuroblastomas, identifying both the primary tumor and sites of metastatic disease. The addition of single photon emission computed tomography (SPECT) and SPECT/computed tomography to (123)I-MIBG planar images can improve identification and characterization of sites of uptake. During scan interpretation, use of MIBG semiquantitative scoring systems improves description of disease extent and distribution and may be helpful in defining prognosis. Therapeutic use of MIBG labeled with iodine 131 ((131)I) is being investigated as part of research trials, both as a single agent and in conjunction with other therapies. (131)I-MIBG therapy has been studied in patients with newly diagnosed neuroblastoma and those with relapsed disease. Development and implementation of an institutional (131)I-MIBG therapy research program requires extensive preparation with a focus on radiation protection.

Neuroblastoma (Peripheral neuroblastic tumours)

Peripheral neuroblastic tumours (PNTs), a family of tumours arising in the embryonal remnants of the sympathetic nervous system, account for 7-10% of all tumours in children. In two-thirds of cases, PNTs originate in the adrenal glands or the retroperitoneal ganglia. At least one third present metastases at onset, with bone and bone marrow being the most frequent metastatic sites. Disease extension, MYCN oncogene status and age are the most relevant prognostic factors, and their influence on outcome have been considered in the design of the recent treatment protocols. Consequently, the probability of cure has increased significantly in the last two decades. In children with localised operable disease, surgical resection alone is usually a sufficient treatment, with 3-year event-free survival (EFS) being greater than 85%. For locally advanced disease, primary chemotherapy followed by surgery and/or radiotherapy yields an EFS of around 75%. The greatest problem is posed by children with metastatic disease or amplified MYCN gene, who continue to do badly despite intensive treatments. Ongoing trials are exploring the efficacy of new drugs and novel immunological approaches in order to save a greater number of these patients.

Incidence and risk factors for secondary malignancy in patients with neuroblastoma after treatment with (131)I-metaiodobenzylguanidine

Several reports of second malignant neoplasm (SMN) in patients with relapsed neuroblastoma after treatment with (131)I-MIBG suggest the possibility of increased risk. Incidence of and risk factors for SMN after (131)I-MIBG have not been defined. This is a multi-institutional retrospective review of patients with neuroblastoma treated with (131)I-MIBG therapy. A competing risk approach was used to calculate the cumulative incidence of SMN from time of first exposure to (131)I-MIBG. A competing risk regression was used to identify potential risk factors for SMN. The analytical cohort included 644 patients treated with (131)I-MIBG. The cumulative incidence of SMN was 7.6% (95% confidence interval [CI], 4.4-13.0%) and 14.3% (95% CI, 8.3-23.9%) at 5 and 10 years from first (131)I-MIBG, respectively. No increase in SMN risk was found with increased number of (131)I-MIBG treatments or higher cumulative activity per kilogram of (131)I-MIBG received (p = 0.72 and p = 0.84, respectively). Thirteen of the 19 reported SMN were haematologic. In a multivariate analysis controlling for variables with p < 0.1 (stage, age at first (131)I-MIBG, bone disease, disease status at time of first (131)I-MIBG), patients with relapsed/progressive disease had significantly lower risk of SMN (subdistribution hazard ratio 0.3, 95% CI, 0.1-0.8, p = 0.023) compared to patients with persistent/refractory neuroblastoma. The cumulative risk of SMN after (131)I-MIBG therapy for patients with relapsed or refractory neuroblastoma is similar to the greatest published incidence for high-risk neuroblastoma after myeloablative therapy, with no dose-dependent increase. As the number of patients treated and length of follow-up time increase, it will be important to reassess this risk.

Individualized 131I-mIBG therapy in the management of refractory and relapsed neuroblastoma

OBJECTIVE

Iodine-131-labelled meta-iodobenzylguanidine (I-mIBG) therapy is an established treatment modality for relapsed/refractory neuroblastoma, most frequently administered according to fixed or weight-based criteria. We evaluate response and toxicity following a dosimetry-based, individualized approach.

MATERIALS AND METHODS

A review of 44 treatments in 25 patients treated with I-mIBG therapy was performed. Patients received I-mIBG therapy following relapse (n=9), in refractory disease (n=12), or with surgically unresectable disease despite conventional treatment (n=4). Treatment schedule (including mIBG dose and number of administrations) was individualized according to the clinical status of the patient and dosimetry data from either a tracer study or previous administrations. Three-dimensional tumour dosimetry was also performed for eight patients.

RESULTS

The mean administered activity was 11089±7222 MBq and the mean whole-body dose for a single administration was 1.79±0.57 Gy. Tumour-absorbed doses varied considerably (3.70±3.37 mGy/MBq). CTCAE grade 3/4 neutropenia was documented following 82% treatments and grade 3/4 thrombocytopenia following 71% treatments. Further acute toxicity was found in 49% of patients. All acute toxicities resolved with appropriate therapy. The overall response rate was 58% (complete or partial response), with a further 29% of patients having stable disease.

CONCLUSION

A highly personalized approach combining patient-specific dosimetry and clinical judgement enables delivery of high activities that can be tolerated by patients, particularly with stem cell support. We report excellent response rates and acceptable toxicity following individualized I-mIBG therapy.

Extended Sedation With Continuous Midazolam or Dexmedetomidine Infusion for Young Children Receiving 131 I-MIBG Radiopharmaceutical Therapy for Advanced Neuroblastoma

BACKGROUND

(131) I-MIBG is increasingly used for treating neuroblastoma; however, administration requires careful adherence to radiation safety guidelines. We describe our experience using continuous sedation to facilitate safe (131) I-MIBG therapy for young children.

PROCEDURE

Patients were included in this case series if they received continuous midazolam or dexmedetomidine infusion for sedation during (131) I-MIBG therapy from November 1, 2012, to October 1, 2014. Key outcomes included adequacy of sedation for both (131) I-MIBG infusion and the duration of radioactive isolation, as well as sedative-related toxicities. Additionally, nuclear medicine scans before and after (131) I-MIBG therapy were assessed using the Curie score. These scores were compared qualitatively between midazolam, dexmedetomidine, and control (no sedative infusion) groups.

RESULTS

Of the 13 patients receiving continuous sedation for (131) I-MIBG therapy, seven achieved adequate sedation with midazolam, five achieved adequate sedation with dexmedetomidine, one patient (1.6 years old) failed to achieve adequate sedation with either medication and did not receive (131) I-MIBG therapy. Sedation was generally well tolerated. Common side effects for dexmedetomidine infusion included hypotension and relative bradycardia. Both treatment and control groups had multiple patients with increased Curie scores post-(131) I-MIBG therapy. However, one patient in the midazolam group and two in the dexmedetomidine group had decreased Curie scores after (131) I-MIBG therapy, while none decreased in the control group.

CONCLUSIONS

Although we cannot exclude the possibility of some inhibition of (131) I-MIBG uptake by midazolam or dexmedetomidine, this case series suggests that continuous infusions of either agent can provide effective sedation to allow safe administration of (131) I-MIBG to young patients.

Arsenic Trioxide as a Radiation Sensitizer for 131I-Metaiodobenzylguanidine Therapy: Results of a Phase II Study

Arsenic trioxide has in vitro and in vivo radiosensitizing properties. We hypothesized that arsenic trioxide would enhance the efficacy of the targeted radiotherapeutic agent (131)I-metaiodobenzylguanidine ((131)I-MIBG) and tested the combination in a phase II clinical trial.

METHODS

Patients with recurrent or refractory stage 4 neuroblastoma or metastatic paraganglioma/pheochromocytoma (MP) were treated using an institutional review board-approved protocol (Clinicaltrials.gov identifier NCT00107289). The planned treatment was (131)I-MIBG (444 or 666 MBq/kg) intravenously on day 1 plus arsenic trioxide (0.15 or 0.25 mg/m(2)) intravenously on days 6-10 and 13-17. Toxicity was evaluated using National Cancer Institute Common Toxicity Criteria, version 3.0. Response was assessed by International Neuroblastoma Response Criteria or (for MP) by changes in (123)I-MIBG or PET scans.

RESULTS

Twenty-one patients were treated: 19 with neuroblastoma and 2 with MP. Fourteen patients received (131)I-MIBG and arsenic trioxide, both at maximal dosages; 2 patients received a 444 MBq/kg dose of (131)I-MIBG plus a 0.15 mg/kg dose of arsenic trioxide; and 3 patients received a 666 MBq/kg dose of (131)I-MIBG plus a 0.15 mg/kg dose of arsenic trioxide. One did not receive arsenic trioxide because of transient central line-induced cardiac arrhythmia, and another received only 6 of 10 planned doses of arsenic trioxide because of grade 3 diarrhea and vomiting with concurrent grade 3 hypokalemia and hyponatremia. Nineteen patients experienced myelosuppression higher than grade 2, most frequently thrombocytopenia (n = 18), though none required autologous stem cell rescue. Twelve of 13 evaluable patients experienced hyperamylasemia higher than grade 2 from transient sialoadenitis. By International Neuroblastoma Response Criteria, 12 neuroblastoma patients had no response and 7 had progressive disease, including 6 of 8 entering the study with progressive disease. Objective improvements in semiquantitative (131)I-MIBG scores were observed in 6 patients. No response was seen in MP. Seventeen of 19 neuroblastoma patients continued on further chemotherapy or immunotherapy. Mean 5-year overall survival (±SD) for neuroblastoma was 37% ± 11%. Mean absorbed dose of (131)I-MIBG to blood was 0.134 cGy/MBq, well below myeloablative levels in all patients.

CONCLUSION

(131)I-MIBG plus arsenic trioxide was well tolerated, with an adverse event profile similar to that of (131)I-MIBG therapy alone. The addition of arsenic trioxide to (131)I-MIBG did not significantly improve response rates when compared with historical data with (131)I-MIBG alone.

Upfront treatment of high-risk neuroblastoma with a combination of 131I-MIBG and topotecan

BACKGROUND

(131)I-metaiodobenzylguanidine ((131) I-MIBG) has a significant anti-tumor effect against neuroblastoma (NBL). Topotecan (TPT) can act as a radio-sensitizer and can up-regulate (131) I-MIBG uptake in vitro in NBL.

AIM

Determine the efficacy of the combination of (131) I-MIBG with topotecan in newly diagnosed high-risk (HR) NBL patients.

METHODS

In a prospective, window phase II study, patients with newly diagnosed high-risk neuroblastoma were treated at diagnosis with two courses of (131) I-MIBG directly followed by topotecan (0.7 mg/m(2) for 5 days). After these two courses, standard induction treatment (four courses of VECI), surgery and myeloablative therapy (MAT) with autologous stem cell transplantation (ASCT) was given. Response was measured after two courses of (131) I-MIBG-topotecan and post MAT and ASCT. Hematologic toxicity and harvesting of stem cells were analysed. Topoisomerase-1 activity levels were analysed in primary tumor material.

RESULTS

Sixteen patients were included in the study; median age was 2.8 years. MIBG administered activity (AA) (median and range) of the first course was 0.5 (0.4-0.6) GBq/kg (giga Becquerel/kilogram) and of the second course 0.4 (0.3-0.5) GBq/kg. The overall objective response rate (ORR) after 2 × MIBG/TPT was 57%, the primary tumor RR was 94%, and bone marrow RR was 43%. The ORR post MAT and ASCT was 57%. Hematologic grade four toxicity: after first and second (131) I-MIBG (platelets 25/33%, neutrophils 13/33%, and hemoglobin 25/7%). Topoisomerase-1 activity levels were increased in 10/10 (100%) measured tumors.

CONCLUSIONS

Combination therapy with MIBG-topotecan is an effective window treatment in newly diagnosed high-risk neuroblastoma patients.

Minimal residual disease detection in autologous stem cell grafts from patients with high risk neuroblastoma

BACKGROUND

The clinical significance of minimal residual disease (MRD) detected by real-time quantitative PCR (qPCR) in autologous stem cell grafts in high risk neuroblastoma is still controversial. In this retrospective multicenter study, autologous stem cell grafts of a large cohort were studied using a panel of RNA markers.

PROCEDURE

From 104 patients with high risk neuroblastoma, who received autologous stem cell transplantation as first line treatment, 66 peripheral blood stem cells (PBSC) and 38 CD34+ selected grafts were retrospectively collected at 2 Dutch and 12 German centers between 1997 and 2010. To investigate graft contamination qPCR was performed by using 5 neuroblastoma specific markers (PHOX2B, TH, DDC, CHRNA3, and DBH).

RESULTS

In PBSC 6/66 (9%) and in CD34+ selected grafts 3/38 (8%) samples were contaminated. Graft contamination was not associated with an unfavorable outcome (5-years OS, 66% vs. 50.5%; P=0.6 and 5-years EFS, 22% vs. 35%, P=0.7). In multivariate Cox analysis BM MRD at time of harvest was significantly associated with survival (P=0.008 OS and P=0.002 EFS), but graft contamination was still not associated with an unfavorable outcome (P=0.9 OS and P=1 EFS).

CONCLUSIONS

Graft contamination is very infrequent in this retrospective cohort of patients with no or minimal BM disease prior to stem cell collection and does not influence outcome in univariate and multivariate analysis. The presence of MRD at time of harvest is a strong outcome predictor. However, these results will have to be verified in a large prospective study.

Iodine-131 metaiodobenzylguanidine therapy for neuroblastoma: reports so far and future perspective

Neuroblastoma, which derives from neural crest, is the most common extracranial solid cancer in childhood. The tumors express the norepinephrine (NE) transporters on their cell membrane and take in metaiodobenzylguanidine (MIBG) via a NE transporter. Since iodine-131 (I-131) MIBG therapy was firstly reported, many trails of MIBG therapy in patients with neuroblastoma were performed. Though monotherapy with a low dose of I-131 MIBG could achieve high-probability pain reduction, the objective response was poor. In contrast, more than 12 mCi/kg I-131 MIBG administrations with or without hematopoietic cell transplantation (HCT) obtain relatively good responses in patients with refractory or relapsed neuroblastoma. The combination therapy with I-131 MIBG and other modalities such as nonmyeloablative chemotherapy and myeloablative chemotherapy with HCT improved the therapeutic response in patients with refractory or relapsed neuroblastoma. In addition, I-131 MIBG therapy incorporated in the induction therapy was proved to be feasible in patients with newly diagnosed neuroblastoma. To expand more the use of MIBG therapy for neuroblastoma, further studies will be needed especially in the use at an earlier stage from diagnosis, in the use with other radionuclide formations of MIBG, and in combined use with other therapeutic agents.

Medical imaging in personalised medicine: a white paper of the research committee of the European Society of Radiology (ESR)

The future of medicine lies in early diagnosis and individually tailored treatments, a concept that has been designated 'personalised medicine' (PM), which aims to deliver the right treatment to the right patient at the right time. Medical imaging has always been personalised and is fundamental to almost all aspects of PM. It is instrumental in solving clinical differential diagnoses. Imaging procedures are tailored to the clinical problem and patient characteristics. Screening for preclinical disease is done with imaging. Stratification based on imaging biomarkers can help identify individuals suited for preventive intervention. Treatment decisions are based on the in vivo visualisation of the location and extent of an abnormality, as well as the loco-regional physiological, biochemical and biological processes using structural and molecular imaging. Image-guided biopsy provides relevant tissue specimens for genetic/molecular characterisation. In addition, radiogenomics relate imaging biomarkers to these genetic and molecular features. Furthermore, imaging is essential to patient-tailored therapy planning, therapy monitoring and follow-up of disease, as well as targeting non-invasive or minimally invasive treatments, especially with the rise of theranostics. Radiologists need to be prepared for this new paradigm as it will mean changes in training, clinical practice and in research. Key Points • Medical imaging is a key component in personalised medicine • Personalised prevention will rely on image-based screening programmes • Anatomical, functional and molecular imaging biomarkers affect decisions on the type and intensity of treatment • Treatment response assessment with imaging will improve personalised treatment • Image-based invasive intervention integrates personalised diagnosis and personalised treatment.