The Experience of Children With Neuroblastoma and Their Parents During Single-Room Isolation for 131I-Metaiodobenzylguanidine Therapy: A Qualitative Descriptive Study

Background: Administration of 131I-metaiodobenzylguanidine (131I-MIBG) for neuroblastoma requires hospitalization in single-room isolation and limits caregiver physical contact due to the child's radioactive burden. Though used for decades, there is a dearth of research on the experiences of children and their parents while isolated. Methods: This qualitative descriptive study evaluated the experience of children with neuroblastoma undergoing single-room isolation for 131I-MIBG therapy and their parents. Ten nurses, nine parents, and five children were interviewed; transcripts were analyzed applying a conventional content analysis approach. Results: Child themes included overall experiences ranging from positive to negative; emotional stress was common; symptoms were common but mostly managed; the children were adequately prepared for isolation; and audiovisual technology and entertainment helped. The indwelling urinary catheter was a source of emotional stress and/or pain for several children. Parent themes included I thought it was going to be a lot worse; it gets better with time; feeling concerned and overwhelmed; prepared as much as you can be; and you feel like you’re not alone. Discussion: Findings suggest that children and parents would benefit from additional coping support interventions to address emotional distress. Efforts should be made to identify other sources of technology or room designs that can maximize the child's sense of connection with parents and healthcare professionals. Additional research is needed to examine the impact of this isolation experience on the long-term psychological outcomes of children and parents.

Application of a tungsten apron for occupational radiation exposure in nursing care of children with neuroblastoma during 131I-meta-iodo-benzyl-guanidine therapy

The use of effective shielding materials against radiation is important among medical staff in nuclear medicine. Hence, the current study investigated the shielding effects of a commercially available tungsten apron using gamma ray measuring instruments. Further, the occupational radiation exposure of nurses during 131I-meta-iodo-benzyl-guanidine (131I-MIBG) therapy for children with high-risk neuroblastoma was evaluated. Attachable tungsten shields in commercial tungsten aprons were set on a surface-ray source with 131I, which emit gamma rays. The mean shielding rate value was 0.1 ± 0.006 for 131I. The shielding effects of tungsten and lead aprons were evaluated using a scintillation detector. The shielding effect rates of lead and tungsten aprons against 131I was 6.3% ± 0.3% and 42.1% ± 0.2% at 50 cm; 6.1% ± 0.5% and 43.3% ± 0.3% at 1 m; and 6.4% ± 0.9% and 42.6% ± 0.6% at 2 m, respectively. Next, we assessed the occupational radiation exposure during 131I-MIBG therapy (administration dose: 666 MBq/kg, median age: 4 years). The total occupational radiation exposure dose per patient care per 131I-MIBG therapy session among nurses was 0.12 ± 0.07 mSv. The average daily radiation exposure dose per patient care among nurses was 0.03 ± 0.03 mSv. Tungsten aprons had efficient shielding effects against gamma rays and would be beneficial to reduce radiation exposures per patient care per 131I-MIBG therapy session.

An open-label, single-arm, multi-center, phase II clinical trial of single-dose [131I]meta-iodobenzylguanidine therapy for patients with refractory pheochromocytoma and paraganglioma

Objective In this phase II study, we aimed to investigate the efficacy and safety of single-dose [131I]meta-iodobenzylguanidine (131I-mIBG) therapy in patients with refractory pheochromocytoma and paraganglioma (PPGL). Patients and methods This study was designed as an open-label, single-arm, multi-center, phase II clinical trial. The enrolled patients were administered 7.4 GBq of 131I-mIBG. Its efficacy was evaluated 12 and 24 weeks later, and its safety was monitored continuously until the end of the study. We evaluated the biochemical response rate as the primary endpoint using the one-sided exact binomial test based on the null hypothesis (≤ 5%). Results Seventeen patients were enrolled in this study, of which 16 were treated. The biochemical response rate (≥ 50% decrease in urinary catecholamines) was 23.5% (90% confidence interval: 8.5–46.1%, p = 0.009). The radiographic response rates, determined with CT/MRI according to the response evaluation criteria in solid tumors (RECIST) version 1.1 and 123I-mIBG scintigraphy were 5.9% (0.3%–25.0%) and 29.4% (12.4%–52.2%), respectively. The most frequent non-hematologic treatment-emergent adverse events (TEAEs) were gastrointestinal symptoms including nausea, appetite loss, and constipation, which were, together, observed in 15 of 16 patients. Hematologic TEAEs up to grade 3 were observed in 14 of 16 patients. No grade 4 or higher TEAEs were observed. All patients had experienced at least one TEAE, but no fatal or irreversible TEAEs were observed. Conclusion A single dose 131I-mIBG therapy was well tolerated by patients with PPGL, and statistically significantly reduced catecholamine levels compared to the threshold response rate, which may lead to an improved prognosis for these patients.

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.

PRIMARY HYPOTHYROIDISM IN A HIGH-RISK NEUROBLASTOMA PATIENT AFTER 131I-MIBG THERAPY: A CLINICAL CASE REPORT AND LITERATURE REVIEW

In recent decades, there has been marked progress in understanding the biology of the most common extracranial solid tumor of childhood – neuroblastoma (NB), which led to a significant improvement in treatment outcomes due to stratification of patients into risk groups, intensification of treatment of patients with metastatic disease and the presence of unfavorable molecular genetic markers. Survivors who have received multimodal therapies, including chemotherapy, high-dose therapy and autologous peripheral stem-cell transplantation, 131I-metaiodobenzylguanidine (131I-MIBG) therapy, radiation therapy, and immunotherapy have a high risk of developing long-term side effects of treatment (LT SE). The study of the nature and frequency of LT SE after completion of therapy in patients with NB is important to ensure the quality of life and minimize severe health disorders. This article presents a literature review and description of a clinical case report of primary hypothyroidism in a high-risk patient with NB who received multicomponent treatment, including 131I-metaiodobenzylguanidine therapy due to the persistence of MIBG-positive foci after the induction chemotherapy.

Changes in ctDNA levels after MIBG therapy in patients with relapsed or refractory neuroblastoma.

10012 Background: Circulating tumor DNA (ctDNA) is detectable in children with neuroblastoma. Less is known about how levels change during treatment and the implications of these changes. We evaluated ctDNA pre- and post- 131I-metaiodobenzylguanidine (MIBG) therapy. Methods: We utilized plasma samples from NANT11-01 (NCT02035137), a multi-center, open label, randomized phase II clinical trial evaluating MIBG with or without radiation sensitizers for patients with relapsed or refractory neuroblastoma. Plasma was collected at Baseline prior to MIBG, 72 hours (Hr72), 96 hours (Hr96), 15 days after MIBG (D15), and prior to a second course among patients without progression who received a second course (C2). Samples were analyzed for percent ctDNA levels using ultra-low passage whole genome sequencing. We evaluated associations between ctDNA findings with baseline disease measures of percent involvement in bone marrow, Curie score, and RECIST disease sum of diameters as well as overall response by NANT Response Criteria v1.2 (complete response or partial response coded as responders). Results: Eighty-four patients had a baseline sample and were included in this analysis. Of the 37 patients (44%) with detectable ctDNA at baseline, the median ctDNA level was 32% (range 3.9-91%). Baseline ctDNA levels showed a significant positive correlation with percent involvement in bone marrow (r=0.37; p=0.0004) and Curie score (r=0.26; p = 0.018), but not RECIST sum of diameters for soft tissue sites (r=0.065; p=0.56). Following therapy, the proportions of patients with detectable ctDNA were: Hr72 47% (34/73; median level 28%); Hr96 50% (26/52; median 28%); D15 33% (7/21; median 4%); and C2 14% (3/21; median 50%). Rate of ctDNA detection was similar between responders and non-responders at baseline, Hr72, and Hr96, but lower among responders at D15 and C2 (Table). Among the 21 patients with C2 data, ctDNA levels were either undetectable (n=18) or lower than Cycle 1 Baseline (n=3). Among patients with detectable baseline ctDNA, the median relative ctDNA level at Hr72 (Hr72 ctDNA/baseline ctDNA) for non-responders was 0.87 (n=24) vs. 1.16 for responders (n=7). In contrast, the median relative ctDNA level at C2 for non-responders was 0.56 (n=4) vs. 0 for responders (n=4). Conclusions: ctDNA is detectable in a substantial proportion of patients with relapsed / refractory neuroblastoma, with levels correlated with conventional measures of disease burden. Following MIBG therapy, early timepoints (Hr72 and Hr96) are less informative, whereas ctDNA becomes undetectable at D15 and C2 more commonly in patients with clinical response.[Table: see text]

Factors Modifying Outcome After MIBG Therapy in Children With Neuroblastoma—A National Retrospective Study

BackgroundNeuroblastoma is the most common pediatric extracranial tumor with varied prognoses, but the survival of treated refractory or relapsing patients remains poor.ObjectiveThis analysis presents the outcomes of children with neuroblastoma undergoing MIBG therapy in Poland in 2006-2019.Study DesignA retrospective cohort of 55 patients with refractory or relapsed neuroblastoma treated with I-131 MIBG in Poland in 2006-2019 was analyzed. The endpoints were overall survival (OS), event-free survival (EFS), cumulative incidence (CI) of second cancers and CI of hypothyroidism. Survival curves were estimated using the Kaplan-Meier method and compared between the cohorts by the log-rank test. Cox modeling was adopted to estimate hazard ratios for OS and EFS, considering factors with P < 0.2.ResultsFifty-five patients with a median age of 78.4 months (range 18-193) with neuroblastoma underwent one or more (4 patients) courses of MIBG I-131 therapy. Fifteen patients were not administered chemotherapy, 3 children received standard-dose chemotherapy, and 37 patients were administered high-dose chemotherapy (HDCT) (busulfan-melphalan in 24 and treosulfan-based in 12 patients). Forty-six patients underwent stem cell transplantation, with autologous (35 patients), haploidentical (6), allogeneic (4), and syngeneic grafts (1). The median time from first MIBG therapy to SCT was 22 days. Children with relapsing tumors had inferior OS compared to those with primary resistant disease (21.2% vs 58.7%, p=0.0045). Survival was better in patients without MYCN gene amplification. MIBG therapy was never curative, except in patients further treated with HDCT with stem cell rescue irrespective of the donor type. 31 patients were referred for immune therapy after MIBG therapy, and the 5-year OS in this group was superior to the untreated children (55.2% vs 32.7%, p=0.003), but the difference in the 5-year EFS was not significant (25.6% vs 32.9%, p=ns). In 3 patients, a second malignancy was diagnosed. In 19.6% of treated children, hypothyroidism was diagnosed within 5 years after MIBG therapy.ConclusionMIBG therapy can be incorporated into the therapeutic strategy of relapsed or resistant neuroblastoma patients as preconditioning with HDCT rather than stand-alone therapy. Follow-up is required due to the incidence of thyroid failure and risk of second cancers.

Pivotal Role of Dosimetry in High Activity 131i Mibg Therapy in Patients Affected by High Risk Relapsed Refractory Neuroblastoma: Towards a Deeper Metastatic Response Understanding

Background: Dosimetry in molecular radiotherapy for personalized treatment is assuming a central role in clinical management of aggressive/relapsed tumors. High-Risk relapsed/refractory metastatic Neuroblastoma (HRrrm-NBL) has a poor prognosis and high-activity 131I-mIBG therapy could represent a promising strategy.The aim of this study was to report the absorbed dose to whole-body (DWB), red marrow (DRM) and lesions (DLesion) correlated to clinical outcome.Methods: 14 patients affected by HRrrm-NBL were treated with high-activity 131I-mIBG therapy (two administrations separated by 15 days). The first administration was weight-based whereas the second one was dosimetry-based (achieving 4 Gy to whole-body). In all patients DWB and DRM has been assessed; 9/14 patients were selected for DLesion evaluation (for a total of 13 lesions). Treatment response was classified in Progression and Stable Disease (PD and SD), Partial and Complete Response (PR and CR) and correlated to the value of DLesion value.Results: The cumulative DWB, DRM and DLesion ranged from [1.49; 4.45], [0.99; 2.56] and [44.17; 585.75] Gy. After treatment 3, 2, 4 and 5 patients showed CR, PR, SD and PD respectively showing a correlation between the clinical outcome and DLesion with a threshold at 80 Gy.Conclusions: Our experience shows feasibility of high activity therapy of 131I MIBG in rrmHR-NBL children as two administration intensive strategy. Dosimetric approach allowed a tailored high dose treatment maximizing the benefits of radionuclide therapy for pediatric patients with a safety profile. The assesment of DLesion contributed to have a deeper understaning of metabolic treatment effects.

High-specific-activity 131iodine-metaiodobenzylguanidine for therapy of unresectable pheochromocytoma and paraganglioma

Pheochromocytomas and paragangliomas (PPG) are rare cancers arising from the adrenal medulla (pheochromocytoma) or autonomic ganglia (paraganglioma). They have highly variable biological behavior. Most PPG express high affinity norepinephrine transporters, allowing active uptake of the norepinephrine analog, 131iodine-metaiodobenzylguanidine (131I-MIBG). Low-specific-activity forms of 131I-MIBG have been used since 1983 for therapy of PPG. High-specific-activity-131I-MIBG therapy improves hypertension management, induces partial radiological response or stable disease, decreases biochemical markers of disease activity and is well tolerated by patients. This drug, approved in the USA in July 2018, is the first approved agent for patients with unresectable, locally advanced or metastatic PPG and imaging evidence of metaiodobenzylguanidine uptake, who require systemic anticancer therapy.