Safety and efficacy of multiple-dose versus single-dose MIBG therapy in patients with refractory pheochromocytoma and paraganglioma: a single-center retrospective analysis.

OBJECTIVE: To investigate the incidence of adverse events (AEs) following single and multiple administrations of I-131 metaiodobenzylguanidine (MIBG) therapy for inoperable pheochromocytomas and paragangliomas (PPGLs). METHODS: A single-center retrospective study was conducted on patients with inoperable PPGLs who underwent I-131 MIBG therapy between January 2000 and December 2020. A total of 28 patients with available electronic medical records were included. The treatment consisted of a single intravenous administration of 150 mCi (5.55 GBq) of I-131 MIBG. We evaluated the first MIBG treatment and repeated MIBG treatments performed within 200 days of the previous treatment. AEs for each treatment were evaluated using CTCAE version 4.0, and the statistical analysis was conducted at a significance level of p < 0.05. Objective response based on RECIST 1.1 criteria and biochemical response based on urinary catecholamines were assessed. RESULTS: The study included a total of 63 administrations, consisting of 28 single administrations (SAs), including the first administration for all 28 cases, and 35 multiple administrations (MAs), which included the second or later administrations. Hematological AEs were evaluable for 23 SAs and 29 MAs. Grade 3 or higher leukopenia occurred in 9.8% of all administrations, and Grade 3 or higher lymphopenia in 23.5%; both were manageable through observation. There were no significant differences in clinical AE Grades 1-2 (p = 0.32), hematological AE Grades 1-2 (p = 0.22), or hematological AE Grades 3-4 (p = 0.12) between MAs and SAs. Statistical analysis for each type of AE revealed significant increases in leukopenia (p < 0.01) and lymphopenia (p = 0.04). No significant difference in anemia, thrombocytopenia, or neutropenia was observed between MAs and SAs. There was no significant increase in the incidence rate of Grade 3 or higher hematological AEs for any of the parameters. The objective response rate was 0% for SAs and 36% for MAs. Biochemical response rates were 18% for SAs and 67% for MAs. CONCLUSION: In I-131 MIBG therapy for PPGLs, multiple administrations significantly increased only Grade 1 or 2 lymphopenia and leukopenia compared to single administration.

Incidence of subclinical and overt hypothyroidism in children treated with [131I]mIBG: a systematic review and meta-analysis.

INTRODUCTION: Treatment with [131I]mIBG is commonly used in pediatric metastatic neuroblastoma (NB); however, unbound [131I]I might be taken up by the thyroid, causing hypothyroidism. To prevent this occurrence, thyroid blockade with iodine salts is commonly used; despite this precaution, thyroid dysfunction still occurs. This review and meta-analysis aim to clarify the mean frequency of hypothyroidism in children with NB treated with [131I]mIBG and to investigate the possible causes. EVIDENCE ACQUISITION: The literature was searched for English-language scientific manuscripts describing the incidence of TSH elevation and overt hypothyroidism in children with NB treated with [131I]mIBG. Preclinical studies, small-case series, and reviews were excluded. A proportion meta-analysis was conducted to test the influence of potentially relevant factors (type and duration of thyroid blockade, year of the study, sample size) on the incidence of TSH elevation/overt hypothyroidism. EVIDENCE SYNTHESIS: Eleven studies were included. The pooled percentage of TSH elevation was 0.41 (95% CI: 0.27-0.55); the duration of the thyroid blockade (P=0.004) was inversely correlated with the incidence of TSH elevation. Moreover, a TSH increase was more common in patients treated with potassium iodide (KI) alone than in those managed with a multi-drug thyroid blockade (P<0.001). The pooled percentage of children requiring hormone replacement therapy was 0.33 (95% CI: 0.16-0.49). As in the case of TSH elevation, a longer duration of the thyroid blockade (P=0.006) and a multi-pronged approach (P<0.001) were associated with a lower incidence of overt hypothyroidism. CONCLUSIONS: Hypothyroidism appears to occur frequently in children treated with [131I]mIBG, which should be monitored closely after the radionuclide treatment to start hormone replacement therapy as soon as needed. The duration, as well as the type of thyroid blockade, seem to influence the incidence of hypothyroidism; however, more data from prospective evaluations are needed.

Phase II study of 131 I-metaiodobenzylguanidine with 5 days of topotecan for refractory or relapsed neuroblastoma: Results of the French study MIITOP.

PURPOSE: We report the results of the French multicentric phase II study MIITOP (NCT00960739), which evaluated tandem infusions of 131 I-metaiodobenzylguanidine (mIBG) and topotecan in children with relapsed/refractory metastatic neuroblastoma (NBL). METHODS: Patients received 131 I-mIBG on day 1, with intravenous topotecan daily on days 1-5. A second activity of 131 I-mIBG was given on day 21 to deliver a whole-body radiation dose of 4 Gy, combined with a second course of topotecan on days 21-25. Peripheral blood stem cells were infused on day 31. RESULTS: Thirty patients were enrolled from November 2008 to June 2015. Median age at diagnosis was 5.5 years (2-20). Twenty-one had very high-risk NBL (VHR-NBL), that is, stage 4 NBL at diagnosis or at relapse, with insufficient response (i.e., less than a partial response of metastases and more than three mIBG spots) after induction chemotherapy; nine had progressive metastatic relapse. Median Curie score at inclusion was 6 (1-26). Median number of prior lines of treatment was 3 (1-7). Objective response rate was 13% (95% confidence interval [CI]: 4-31) for the whole population, 19% for VHR-NBL, and 0% for progressive relapses. Immediate tolerance was good, with nonhematologic toxicity limited to grade-2 nausea/vomiting in eight patients. Two-year event-free survival was 17% (95% CI: 6-32). Among the 16 patients with VHR-NBL who had not received prior myeloablative busulfan-melphalan consolidation, 13 had at least stable disease after MIITOP; 11 subsequently received busulfan-melphalan; four of them were alive (median follow-up: 7 years). CONCLUSION: MIITOP showed acceptable tolerability in this heavily pretreated population and encouraging survival rates in VHR-NBL when followed by busulfan-melphalan.

Efficacy and Safety of 124I-MIBG Dosimetry-Guided High-Activity 131I-MIBG Therapy of Advanced Pheochromocytoma or Neuroblastoma.

We aim to evaluate the efficacy and safety of 124I-metaiodobenzylguanidine (MIBG) dosimetry-guided high-activity 131I-MIBG therapy of advanced pheochromocytoma or neuroblastoma. Methods: Fourteen patients with advanced pheochromocytoma or neuroblastoma, age 9-69 y, underwent 124I-MIBG PET scans and whole-body retention measurements to assess the whole-body dose as a surrogate of bone marrow toxicity and tumor (absorbed) dose per unit of administered activity. Dosimetry results together with individual patient characteristics were combined to guide a single therapeutic activity to achieve a high tumor dose without exceeding toxicity threshold. Toxicity was assessed for hematologic, hepatic, and renal function. Response was evaluated by RECIST, International Society of Pediatric Oncology Europe Neuroblastoma-like score, change in PET uptake, and quantitative PET parameters (SUVmax, SUVpeak, metabolic tumor volume, total lesion glycolysis), as well as visual decrease in number or in visual intensity of lesions on baseline to follow-up 124I-MIBG PET/CT. Results: The average therapeutic activity was 14 GBq. Eleven of 14 patients (79%) received each more than 10 GBq. One male patient was treated with a single activity of 50 GBq. Three patients were treated with lower activities between 3.5 and 7.0 GBq. Median overall survival was 85 mo (95% CI), and median progression-free survival was 25 mo (95% CI). Four (29%) and 5 (36%) patients demonstrated response (complete response or partial response) by RECIST and functional imaging, respectively. One patient exceeded whole-body dose of 2 Gy and demonstrated grade 3 hematologic toxicity, which resolved spontaneously within 12 mo after the therapy without the need for further treatment. Three patients (21%) demonstrated transient grade 1 renal toxicity. Conclusion: 124I-MIBG dosimetry-guided high-activity 131I-MIBG therapy in patients with advanced pheochromocytoma or neuroblastoma resulted in durable responses with a low rate of manageable adverse events. Efficacy of 124I-MIBG-guided activity escalation should further be assessed in a prospective setting.

Nurses' Experiences Caring for Children With Neuroblastoma Receiving 131I-Metaiodobenzylguanidine Therapy: A Qualitative Descriptive Study.

Background: Neuroblastoma, the most common extra-cranial solid tumor found in children, carries a high mortality rate due to challenges with metastatic disease at diagnoses and relapse. 131I-Metaiodobenzylguanidine (I-MIBG) therapy provides targeted radiotherapy to treat neuroblastoma, but requires children to be isolated for radiation exposure, with limited access to the healthcare team while hospitalized. There is minimal research outlining the nurses' perspectives on caring for this patient population. Therefore, the aim of this study was to describe the nurses' experiences caring for children receiving 131I-MIBG therapy, focusing on nursing care, challenges, radiation exposure, and preparation. Methods: Ten nurses were recruited using purposeful sampling for this qualitative descriptive study. Semi-structured interview guides and conventional qualitative content analysis guided the data collection and analysis. Results: Nurses overwhelmingly felt isolated from their patients and a decreased sense of connection with the child. Although nurses felt prepared, they had more anxiety with the first patient experience and identified that parent engagement was essential. Overall, nurses shared they had support from written materials outlining the protocols, and members of the multidisciplinary team. More concern for radiation exposure was expressed by nurses of childbearing age and with handling bodily fluids. Discussion: Findings suggest that nurses would benefit from simulation experiences to help prepare for radiation exposure safety, strategies to engage the family in the child's care, and interacting with a child in single-room isolation. Because programs differ around the US, additional research exploring nurses' experiences is warranted to evaluate the best successes in providing 131I-MIBG therapy.

Modulation of Radiation Biomarkers in a Randomized Phase II Study of 131I-MIBG With or Without Radiation Sensitizers for Relapsed or Refractory Neuroblastoma.

PURPOSE: 131I-metaiodobenzylguanidine (131I-MIBG) has demonstrated efficacy as a single agent in neuroblastoma. Recent trials have focused on 131I-MIBG combination strategies, though little is known about the effect of putative radiosensitizers on biological markers of radiation exposure. METHODS AND MATERIALS: NANT2011-01 evaluated 131I-MIBG therapy alone (arm A) or in combination with vincristine/irinotecan (arm B) or vorinostat (arm C) for patients with relapsed or refractory neuroblastoma. Blood samples were collected before and after 131I-MIBG infusion to determine levels of radiation-associated biomarkers (transcript and protein). The association of biomarker with treatment arm, clinical response, and treatment toxicity was analyzed. RESULTS: The cohort included 99 patients who had at least 1 biomarker available for analysis. Significant modulation in most biomarkers between baseline, 72, and 96 hours following 131I-MIBG was observed. Patients in arm C had the lowest degree of modulation in FLT3 ligand protein. Lower baseline BCL2 transcript levels were associated with higher overall response. Patients with greater increases in FLT3 ligand at 96 hours after 131I-MIBG therapy were significantly more likely to have grade 4 thrombocytopenia. Peripheral blood gene expression of the BCL2 family of apoptotic markers (BCL2L1 and BAX transcripts) was significantly associated with grade 4 hematologic toxicity. RNA sequencing demonstrated little overlap in the top modulated peripheral blood transcripts between randomized arms. CONCLUSIONS: Peripheral blood biomarkers relevant to radiation exposure demonstrate significant modulation after 131I-MIBG and concomitant radiation sensitizers affect extent of modulation. Biomarkers related to hematopoietic damage and apoptosis were associated with hematologic toxicity.

Biomarker response to high-specific-activity I-131 meta-iodobenzylguanidine in pheochromocytoma/paraganglioma.

The objective of this study is to present the complete biomarker response dataset from a pivotal trial evaluating the efficacy and safety of high-specific-activity I-131 meta-iodobenzylguanidine in patients with advanced pheochromocytoma or paraganglioma. Biomarker status was assessed and post-treatment responses were analyzed for catecholamines, metanephrines, and serum chromogranin A. Complete biomarker response (normalization) or partial response, defined as at least 50% reduction from baseline if above the normal range, was evaluated at specified time points over a 12-month period. These results were correlated with two other study objectives: blood pressure control and objective tumor response as per RECIST 1.0. In this open-label, single-arm study, 68 patients received at least one therapeutic dose (~18.5 GBq (~500 mCi)) of high-specific-activity I-131 meta-iodobenzylguanidine. Of the patients, 79% and 72% had tumors associated with elevated total plasma free metanephrines and serum chromogranin A levels, respectively. Best overall biomarker responses (complete or partial response) for total plasma free metanephrines and chromogranin A were observed in 69% (37/54) and 80% (39/49) of patients, respectively. The best response for individual biomarkers was observed 6-12 months following the first administration of high-specific-activity I-131 meta-iodobenzylguanidine. Biochemical tumor marker response was significantly associated with both reduction in antihypertensive medication use (correlation coefficient 0.35; P = 0.006) as well as objective tumor response (correlation coefficient 0.36; P = 0.007). Treatment with high-specific-activity I-131 meta-iodobenzylguanidine resulted in long-lasting biomarker responses in patients with advanced pheochromocytoma or paraganglioma that correlated with blood pressure control and objective response rate. ClinicalTrials.gov number: NCT00874614.

Failure modes and effects analysis of pediatric I-131 MIBG therapy: Program design and potential pitfalls.

BACKGROUND: There is growing interest among pediatric institutions for implementing iodine-131 (I-131) meta-iodobenzylguanidine (MIBG) therapy for treating children with high-risk neuroblastoma. Due to regulations on the medical use of radioactive material (RAM), and the complexity and safety risks associated with the procedure, a multidisciplinary team involving radiation therapy/safety experts is required. Here, we describe methods for implementing pediatric I-131 MIBG therapy and evaluate our program's robustness via failure modes and effects analysis (FMEA). METHODS: We formed a multidisciplinary team, involving pediatric oncology, radiation oncology, and radiation safety staff. To evaluate the robustness of the therapy workflow and quantitatively assess potential safety risks, an FMEA was performed. Failure modes were scored (1-10) for their risk of occurrence (O), severity (S), and being undetected (D). Risk priority number (RPN) was calculated from a product of these scores and used to identify high-risk failure modes. RESULTS: A total of 176 failure modes were identified and scored. The majority (94%) of failure modes scored low (RPN <100). The highest risk failure modes were related to training and to drug-infusion procedures, with the highest S scores being (a) caregivers did not understand radiation safety training (O = 5.5, S = 7, D = 5.5, RPN = 212); (b) infusion training of staff was inadequate (O = 5, S = 8, D = 5, RPN = 200); and (c) air in intravenous lines/not monitoring for air in lines (O = 4.5, S = 8, D = 5, RPN = 180). CONCLUSION: Through use of FMEA methodology, we successfully identified multiple potential points of failure that have allowed us to proactively mitigate risks when implementing a pediatric MIBG program.

Preclinical Development of [211At]meta- astatobenzylguanidine ([211At]MABG) as an Alpha Particle Radiopharmaceutical Therapy for Neuroblastoma.

PURPOSE: [131I]meta-iodobenzylguanidine ([131I]MIBG) is a targeted radiotherapeutic administered systemically to deliver beta particle radiation in neuroblastoma. However, relapses in the bone marrow are common. [211At]meta-astatobenzylguanidine ([211At] MABG) is an alpha particle emitter with higher biological effectiveness and short path length which effectively sterilizes microscopic residual disease. Here we investigated the safety and antitumor activity [211At]MABG in preclinical models of neuroblastoma. EXPERIMENTAL DESIGN: We defined the maximum tolerated dose (MTD), biodistribution, and toxicity of [211At]MABG in immunodeficient mice in comparison with [131I]MIBG. We compared the antitumor efficacy of [211At]MABG with [131I]MIBG in three murine xenograft models. Finally, we explored the efficacy of [211At]MABG after tail vein xenografting designed to model disseminated neuroblastoma. RESULTS: The MTD of [211At]MABG was 66.7 MBq/kg (1.8 mCi/kg) in CB17SC scid-/- mice and 51.8 MBq/kg (1.4 mCi/kg) in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. Biodistribution of [211At]MABG was similar to [131I]MIBG. Long-term toxicity studies on mice administered with doses up to 41.5 MBq/kg (1.12 mCi/kg) showed the radiotherapeutic to be well tolerated. Both 66.7 MBq/kg (1.8 mCi/kg) single dose and fractionated dosing 16.6 MBq/kg/fraction (0.45 mCi/kg) × 4 over 11 days induced marked tumor regression in two of the three models studied. Survival was significantly prolonged for mice treated with 12.9 MBq/kg/fraction (0.35 mCi/kg) × 4 doses over 11 days [211At]MABG in the disseminated disease (IMR-05NET/GFP/LUC) model (P = 0.003) suggesting eradication of microscopic disease. CONCLUSIONS: [211At]MABG has significant survival advantage in disseminated models of neuroblastoma. An alpha particle emitting radiopharmaceutical may be effective against microscopic disseminated disease, warranting clinical development.

Thyroid function after diagnostic 123I-metaiodobenzylguanidine in children with neuroblastic tumors.

BACKGROUND: Metaiodobenzylguanidine (MIBG) labeled with radioisotopes can be used for diagnostics 123I-) and treatment (131I-) in patients with neuroblastic tumors. Thyroid dysfunction has been reported in 52% of neuroblastoma (NBL) survivors after 131I-MIBG, despite thyroid protection. Diagnostic 123I-MIBG is not considered to be hazardous for thyroid function; however, this has never been investigated. Therefore, the aim of this study was to evaluate the prevalence of thyroid dysfunction in survivors of a neuroblastic tumor who received diagnostic 123I-MIBG only. METHODS: Thyroid function and uptake of 123I- in the thyroid gland after 123I-MIBG administrations were evaluated in 48 neuroblastic tumor survivors who had not been treated with 131I-MIBG. All patients had received thyroid prophylaxis consisting of potassium iodide or a combination of potassium iodide, thiamazole and thyroxine during exposure to 123I-MIBG. RESULTS: After a median follow-up of 6.6 years, thyroid function was normal in 46 of 48 survivors (95.8%). Two survivors [prevalence 4.2% (95% CI 1.2-14.0)] had mild thyroid dysfunction. In 29.2% of the patients and 11.1% of images 123I- uptake was visible in the thyroid. In 1 patient with thyroid dysfunction, weak uptake of 123I- was seen on 1 of 10 images. CONCLUSIONS: The prevalence of thyroid dysfunction does not seem to be increased in patients with neuroblastic tumors who received 123I-MIBG combined with thyroid protection. Randomized controlled trials are required to investigate whether administration of 123I-MIBG without thyroid protection is harmful to the thyroid gland.

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.

Phase I/II clinical trial of high-dose [131I] meta-iodobenzylguanidine therapy for high-risk neuroblastoma preceding single myeloablative chemotherapy and haematopoietic stem cell transplantation.

PURPOSE: Paediatric high-risk neuroblastoma has poor prognosis despite modern multimodality therapy. This phase I/II study aimed to determine the safety, dose-limiting toxicity (DLT), and efficacy of high-dose 131I-meta-iodobenzylguanidine (131I-mIBG) therapy combined with single high-dose chemotherapy (HDC) and haematopoietic stem cell transplantation (HSCT) in high-risk neuroblastoma in Japan. METHODS: Patients received 666 MBq/kg of 131I-mIBG and single HDC and HSCT from autologous or allogeneic stem cell sources. The primary endpoint was DLT defined as adverse events associated with 131I-mIBG treatment posing a significant obstacle to subsequent HDC. The secondary endpoints were adverse events/reactions, haematopoietic stem cell engraftment and responses according to the Response Evaluation Criteria in Solid Tumours version 1.1 (RECIST 1.1) and 123I-mIBG scintigraphy. Response was evaluated after engraftment. RESULTS: We enrolled eight patients with high-risk neuroblastoma (six females; six newly diagnosed and two relapsed high-risk neuroblastoma; median age, 4 years; range, 1-10 years). Although all patients had adverse events/reactions after high-dose 131I-mIBG therapy, we found no DLT. Adverse events and reactions were observed in 100% and 25% patients during single HDC and 100% and 12.5% patients during HSCT, respectively. No Grade 4 complications except myelosuppression occurred during single HDC and HSCT. The response rate according to RECIST 1.1 was observed in 87.5% (7/8) in stable disease and 12.5% (1/8) were not evaluated. Scintigraphic response occurred in 62.5% (5/8) and 37.5% (3/8) patients in complete response and stable disease, respectively. CONCLUSION: 131I-mIBG therapy with 666 MBq/kg followed by single HDC and autologous or allogeneic SCT is safe and efficacious in patients with high-risk neuroblastoma and has no DLT. TRIAL REGISTRATION NUMBER: jRCTs041180030. NAME OF REGISTRY: Feasibility of high-dose iodine-131-meta-iodobenzylguanidine therapy for high-risk neuroblastoma preceding myeloablative chemotherapy and haematopoietic stem cell transplantation (High-dose iodine-131-meta-iodobenzylguanidine therapy for high-risk neuroblastoma). URL OF REGISTRY: https://jrct.niph.go.jp/en-latest-detail/jRCTs041180030 . DATE OF ENROLMENT OF THE FIRST PARTICIPANT TO THE TRIAL: 12/01/2018.

Predicting Response to Chemotherapy in Patients With Newly Diagnosed High-Risk Neuroblastoma: A Report From the International Neuroblastoma Risk Group.

PURPOSE: Metaiodobenzylguanidine (MIBG) scans are a radionucleotide imaging modality that undergo Curie scoring to semiquantitatively assess neuroblastoma burden, which can be used as a marker of therapy response. We hypothesized that a convolutional neural network (CNN) could be developed that uses diagnostic MIBG scans to predict response to induction chemotherapy. METHODS: We analyzed MIBG scans housed in the International Neuroblastoma Risk Group Data Commons from patients enrolled in the Children's Oncology Group high-risk neuroblastoma study ANBL12P1. The primary outcome was response to upfront chemotherapy, defined as a Curie score ≤ 2 after four cycles of induction chemotherapy. We derived and validated a CNN using two-dimensional whole-body MIBG scans from diagnosis and evaluated model performance using area under the receiver operating characteristic curve (AUC). We also developed a clinical classification model to predict response on the basis of age, stage, and MYCN amplification. RESULTS: Among 103 patients with high-risk neuroblastoma included in the final cohort, 67 (65%) were responders. Performance in predicting response to upfront chemotherapy was equivalent using the CNN and the clinical model. Class-activation heatmaps verified that the CNN used areas of disease within the MIBG scans to make predictions. Furthermore, integrating predictions using a geometric mean approach improved detection of responders to upfront chemotherapy (geometric mean AUC 0.73 v CNN AUC 0.63, P < .05; v clinical model AUC 0.65, P < .05). CONCLUSION: We demonstrate feasibility in using machine learning of diagnostic MIBG scans to predict response to induction chemotherapy for patients with high-risk neuroblastoma. We highlight improvements when clinical risk factors are also integrated, laying the foundation for using a multimodal approach to guiding treatment decisions for patients with high-risk neuroblastoma.

[Radiation Protection Against Exposure from Patients Receiving 131I-MIBG and Released from Radiation Treatment Room].

131I-3-iodobenzylguanidine or 131I-iobenguane (3-(131I) iodobenzylguanidine or 131I-iobenguane [131I-MIBG]) is a radioactive agent that is specifically accumulated in tumor cells such as pheochromocytoma and neuroblastoma. Due to its cytotoxic beta ray emitted from 131I, it has been developed as an agent for radioisotope therapy and some researchers have reported its effectiveness. In this study, based on the patients' data from previous clinical trials of 131I-MIBG therapy, we evaluated the radiation safety for public exposure caused by radiation emitted from patients who received 131I-MIBG. In results, it was considered that public exposure and medical exposure of visitors and caregivers to the patients were less than their dose limit and dose constraint by complying the current criteria of the release of patients after therapy with 131I.

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.

A model for in situ plan of care for a critically unstable pediatric patient following I-131 MIBG infusion.

Recent clinical trials have moved iodine-131 (I-131) metaiodobenzylguanidine (MIBG) therapy into frontline management of high-risk neuroblastoma. With this expansion, it is reasonable to anticipate the need for intensive care level resuscitations. Radiation exposure remains the greatest risk to health care professionals managing these patients. We combined shock simulation scenario data with actual radiation dosimetry data to create a care model allowing for aggressive, prolonged in situ resuscitation of a critically ill pediatric patient after I-131 MIBG administration. This model will maintain a critical care provider's radiation level below 10% of the annual occupational dose limit (5 mSv, 500 mrem) per patient managed.

[Thyroid dysfunction due to 131I-metaiodobenzylguanidine in patients with neuroblastoma]. / Disfunción tiroidea por I131-Metayodo Benzilguanidina en pacientes con neuroblastoma.

INTRODUCTION: The treatment of advanced neuroblastoma includes chemotherapy, surgery, and radiotherapy with 131-I-Metaiodobenzylguanidine (131-I-MIBG). Despite strategies to protect thyroid function, its dysfunction is reported between 12 and 85%. OBJECTIVE: To identify the frequency of thyroid dys function in cases of neuroblastoma treated with 131-I-MIBG. PATIENTS AND METHOD: Cross-sectional study. We included all the cases with neuroblastoma treated with 131-I-MIBG between 2002 and 2015, with complete somatometry, and complete thyroid profile (TSH, free and total T3 and T4, and anti-thyroglobulin and antiperoxidase antibodies). RESULTS: 27 patients were identified out of which eleven died (40%). Out of the 16 surviving cases, 9 (56%) presented thyroid dysfunction: 2 (13%) cases with subclinical hypothyroidism and 7 (44%) cases with clinical hypothyroidism (3 cases due to psychomotor developmental delay and 4 due to growth deceleration). The patients presented cli nical manifestations at 16.1 months (1.2-66.3 months) after receiving the radiopharmaceutical at a cumulative dose of 142 mCi (96-391.5 mCi). No differences were found in the age at diagnosis, age at the start of treatment with 131-I-MIBG, the cumulative dose of 131-I-MIBG, and the time elapsed between the dose and the thyroid profile among the cases with or without thyroid dysfunction. Con clusions: 56% of patients with neuroblastoma had thyroid dysfunction. Most of the cases with hy pothyroidism were referred when thyroid dysfunction was clinically evident. A thyroid profile should be performed every 6 months, along with an annual endocrinological evaluation during the next 5 years in these patients.

Disfunción tiroidea por I131-Metayodo Benzilguanidina en pacientes con neuroblastoma / Thyroid dysfunction due to 131I-metaiodobenzylguanidine in patients with neuroblastoma

Resumen: Introducción: El tratamiento del neuroblastoma en estadios avanzados incluye quimioterapia, cirugía y terapia con I131-Metayodo benzilguanidina (I131-MIBG). La disfunción tiroidea se reporta entre 12 y 85% a pesar de la protección tiroidea. Objetivo: Identificar la frecuencia de disfunción tiroidea en casos de neu roblastoma tratados con I131-MIBG. Pacientes y Método: Estudio transversal. Se incluyeron todos los casos con diagnóstico de neuroblastoma que recibieron I131-MIBG en el periodo de 2002-2015, a los cuales se les realizó antropometría completa, perfil de tiroides: hormona estimulante de tiroides (TSH), Triyodotironina total y libre (T3t y T3l), tiroxina total y libre (T4t, T4l), y anticuerpos antitiroglobulina y antiperoxidasa. Resultados: Se identificaron un total de 27 pacientes; once fallecieron (40%). De los 16 casos sobrevivientes, 9 (56%) presentaron disfunción tiroidea: 2 (13%) casos con hipotiroidismo subclínico y 7 (44%) casos con hipotiroidismo clínico (3 casos por retraso en el desa rrollo psicomotor y 4 por desaceleración del crecimiento). Los pacientes presentaron manifestaciones clínicas a los 16,1 meses (1,2-66,3 meses) de recibir el radiofármaco a una dosis acumulada de 142 mCi (96-391.5 mCi). No se logró evidenciar diferencias en la edad al diagnóstico, la edad al inicio del tratamiento con el I131-MIBG, la dosis acumulada del I131-MIBG y el tiempo trascurrido entre la dosis y el perfil tiroideo entre los casos con o sin disfunción tiroidea. Conclusiones: El 56% de los pacientes con neuroblastoma presentaron disfunción tiroidea. La mayoría de los casos con hipotiroidismo fue ron referidos cuando los datos de disfunción tiroidea eran clínicamente evidentes. Se propone en esta poblacion realizar perfil tiroideo semestral y valoración anual por un endocrinólogo pediatra durante los primeros 5 años posteriores al diagnóstico oncológico.

Abstract: Introduction: The treatment of advanced neuroblastoma includes chemotherapy, surgery, and radiotherapy with 131-I-Metaiodobenzylguanidine (131-I-MIBG). Despite strategies to protect thyroid function, its dysfunction is reported between 12 and 85%. Objective: To identify the frequency of thyroid dys function in cases of neuroblastoma treated with 131-I-MIBG. Patients and Method: Cross-sectional study. We included all the cases with neuroblastoma treated with 131-I-MIBG between 2002 and 2015, with complete somatometry, and complete thyroid profile (TSH, free and total T3 and T4, and anti-thyroglobulin and antiperoxidase antibodies). Results: 27 patients were identified out of which eleven died (40%). Out of the 16 surviving cases, 9 (56%) presented thyroid dysfunction: 2 (13%) cases with subclinical hypothyroidism and 7 (44%) cases with clinical hypothyroidism (3 cases due to psychomotor developmental delay and 4 due to growth deceleration). The patients presented cli nical manifestations at 16.1 months (1.2-66.3 months) after receiving the radiopharmaceutical at acumulative dose of 142 mCi (96-391.5 mCi). No differences were found in the age at diagnosis, age at the start of treatment with 131-I-MIBG, the cumulative dose of 131-I-MIBG, and the time elapsed between the dose and the thyroid profile among the cases with or without thyroid dysfunction. Con clusions: 56% of patients with neuroblastoma had thyroid dysfunction. Most of the cases with hypothyroidism were referred when thyroid dysfunction was clinically evident. A thyroid profile should be performed every 6 months, along with an annual endocrinological evaluation during the next 5 years in these patients.

A comparison of thyroid blockade strategies in paediatric 123I-meta-iodobenzylguanidine scanning: a dual centre study.

OBJECTIVE: The aim of this study was to evaluate three thyroid blockade regimes to determine which protocol provides the optimal level of thyroidal protection for paediatric 123-I-meta-iodobenzylguanidine (mIBG) imaging and estimate the relative radiation dose inferred from unbound radioiodine. METHODS: A total of 231 patients were retrospectively evaluated for thyroid uptake and categorised into five subgroups depending upon the protocol of thyroid blockade received. Efficacy of thyroid blockade was established by visual scoring and image quantitation with comparison against a control group. RESULTS: Visual Likert scale responses were subjected to the Mann-Whitney U and Kruskal-Wallis tests, respectively. Statistical significance was reached for observed thyroid uptake in potassium perchlorate recipients (U = 1107, P = 0.001). No statistically significant difference was observed in thyroid uptake for iohexol blockade (U = 176, P = 0.71) or potassium iodate blockade despite variations in iodate dosage and duration (χ(2) = 0.203, P = 0.93). The analyses were repeated for the image quantitation data. A statistically significantly higher absorbed thyroid dose was observed using potassium perchlorate blockade compared with the control group (U = 719, P = 0.001). The Mann-Whitney U did not reach statistical significance in absorbed thyroid dose for iohexol blockade (U = 126, P = 0.209, r = -0.13). The Kruskal-Wallis test, conducted across the potassium iodate groups, did not reach statistical significance (χ(2) = 0.513, P = 0.774). The median absorbed thyroid dose across the iodate groups ranged from 3.58 to 3.91 mGy indicating comparable blockade effectiveness for single-dose potassium iodate. CONCLUSION: Potassium iodate blockade is more efficacious compared with potassium perchlorate within the cohort observed. Both visual and quantitative data indicate that potassium iodate given at 30-60 min before I-mIBG injection provides comparable blockade effectiveness to lengthier administrations, suggesting that a single dose is well tolerated and practical.

Efficacy and Safety of High-Specific-Activity 131I-MIBG Therapy in Patients with Advanced Pheochromocytoma or Paraganglioma.

Patients with metastatic or unresectable (advanced) pheochromocytoma and paraganglioma (PPGL) have poor prognoses and few treatment options. This multicenter, phase 2 trial evaluated the efficacy and safety of high-specific-activity 131I-meta-iodobenzylguanidine (HSA 131I-MIBG) in patients with advanced PPGL. Methods: In this open-label, single-arm study, 81 PPGL patients were screened for enrollment, and 74 received a treatment-planning dose of HSA 131I-MIBG. Of these patients, 68 received at least 1 therapeutic dose (∼18.5 GBq) of HSA 131I-MIBG intravenously. The primary endpoint was the proportion of patients with at least a 50% reduction in baseline antihypertensive medication use lasting at least 6 mo. Secondary endpoints included objective tumor response as assessed by Response Evaluation Criteria in Solid Tumors version 1.0, biochemical tumor marker response, overall survival, and safety. Results: Of the 68 patients who received at least 1 therapeutic dose of HSA 131I-MIBG, 17 (25%; 95% confidence interval, 16%-37%) had a durable reduction in baseline antihypertensive medication use. Among 64 patients with evaluable disease, 59 (92%) had a partial response or stable disease as the best objective response within 12 mo. Decreases in elevated (≥1.5 times the upper limit of normal at baseline) serum chromogranin levels were observed, with confirmed complete and partial responses 12 mo after treatment in 19 of 28 patients (68%). The median overall survival was 36.7 mo (95% confidence interval, 29.9-49.1 mo). The most common treatment-emergent adverse events were nausea, myelosuppression, and fatigue. No patients had drug-related acute hypertensive events during or after the administration of HSA 131I-MIBG. Conclusion: HSA 131I-MIBG offers multiple benefits, including sustained blood pressure control and tumor response in PPGL patients.