Engraftment after myeloablative doses of 131I-metaiodobenzylguanidine followed by autologous bone marrow transplantation for treatment of refractory neuroblastoma

Iodine-131 metaiodobenzylguanidine (131I-mIBG) treatment in relapsed/refractory neuroblastoma

BACKGROUND

I-meta-iodo-benzylguanidine (I-mIBG) therapy has been used in treatment of for advanced neuroblastoma for many years with promising results. There are several studies regarding predictors and outcomes of I-mIBG therapies in relapsed/refractory neuroblastoma patients.

OBJECTIVE

To identify the predictors and outcomes of I-mIBG treatment in relapsed/refractory neuroblastoma.

METHODS

This study was a retrospective review of 22 patients with high risk stage IV relapsed/refractory neuroblastoma who received at least one cycle of I-mIBG therapy. Patient' characteristics, hematologic toxicity, scintigraphic semi-quantitative scoring, and overall survival were recorded. Factors predicting survival were analyzed.

RESULTS

Twenty-two patients (50% male) with mean age of 3.7 years (4.8 months to 8.3 years) received I-mIBG therapies at an average of 3.8 and mean dose of 136 mCi (5032 MBq) per treatment. Most common acute hematologic toxicity was thrombocytopenia. Overall 5-year survival rate was 37% (95% confidence interval: 16.3-58.0) and median survival time was 2.8 year (95% confidence interval: 1.38-6.34). Patients with rising Curie score of ≥25% upon the second therapy were major determinants of overall survival with poorer response to treatment. At least three treatments of I-mIBG were needed to identify some degrees of survival prolongation (crude hazard ratio: P-value = 0.003). Age, sex, metastatic status, and baseline Curie scoring system were good predictors associated with survival. Seven patients (32%) demonstrated objective responses.

CONCLUSION

Despite multimodality therapy, high risk neuroblastoma had a propensity of treatment failure in terms of relapsed or refractory, with some objective responses after I-mIBG treatments. The declined or non-rising Curie score upon second post-treatment total body scan was an important predictor of survival and aided a decision whether or not to proceed with bone marrow transplantation.

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.

Significant correlation between peripheral blood CD34+ cell count in children prior to aphaeresis and CD34+ cell yield following aphaeresis: A single-center experience

Numerous adults' studies demonstrated that preaphaeresis CD34+ cells significantly correlate with the number of CD34+ cells collected by the aphaeresis procedure. Equivalent studies in children are scarce. We studied retrospectively 92 aphaeresis procedures performed following chemotherapy (44) or in steady state (48) in 60 pediatric patients (40 males, 20 females), median age of 7.5 years. Aphaeresis procedures were performed using a SPECTRA Optica (TERUMOBCT) continuous flow cell separator. CD34+ cell concentrations were assessed using flow cytometry. A highly significant correlation between peripheral CD34 cell count on the day of aphaeresis and CD34 cell yield per kg (R²  = .824, P < .0001) was demonstrated. A higher preaphaeresis CD34 cell count was demonstrated in patients with higher preaphaeresis white blood cell count, in patients with brain tumors, and in patients who received chemotherapy as part of their mobilization protocol. A threshold number of 20 peripheral CD34+ cell/μL was found to predict harvesting of 3 × 10⁶ stem cells/kg, and 30 peripheral CD34+ cell/μL for harvesting of 5 × 10⁶ stem cells/kg. This significant correlation between peripheral CD34 cell count and CD34 cell yield, and the threshold number of peripheral CD34 found to predict adequate harvesting can be useful in planning the optimal time for aphaeresis in children.

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.

The potential role of pretransplant MIBG diagnostic scintigraphy in targeted administration of 131I-MIBG accompanied by ASCT for high-risk and relapsed neuroblastoma: a pilot study

MIBG is an effective component in treatment of neuroblastoma. Furthermore, MIBG scintigraphy is an imaging modality in primary assessments. None of the previous studies have evaluated the role of pretransplant MIBG scintigraphy in decision making for neuroblastoma treatment. We selected therapeutic regimen based on pretransplant (131) I-MIBG scintigraphy. Twenty high-risk patients were enrolled. On day -30, patients underwent diagnostic MIBG scintigraphy. Patients were then subdivided into two groups (10 cases in each arm). MIBG-avid subgroup received MIBG (12 mCi/kg), etoposide (1200 mg/m2), carboplatin (1500 mg/m2), and melphalan (210 mg/m2). Non-MIBG-avid subgroup received etoposide (600 mg/m2), carboplatin (1200 mg/m2), and melphalan (150 mg/m2). Patients received CRA after ASCT. Mean age at diagnosis was 42.5 months (range, 17-65) in MIBG-avid and 38.9 months (range, 18-65) in non-MIBG-avid patients. Mean age at diagnosis and transplantation did not reveal significant difference between two subgroups. In MIBG-avid patients, the three-yr OS was 66 ± 21%. In MIBG-non-avid subgroup, the three-yr OS was 53 ± 20%. In MIBG-avid and non-MIBG-avid subgroups, the three-yr EFS were 66 ± 21% and 47 ± 19%, respectively. These findings may suggest an effective role in selecting the therapeutic strategy for pre-ASCT MIBG scintigraphy in high-risk neuroblastoma. MIBG-avid subset may benefit from the combination of therapeutic MIBG and high dose of chemotherapy.

A systematic review of 131I-meta iodobenzylguanidine molecular radiotherapy for neuroblastoma

The optimal use and effectiveness of (131)I-meta iodobenzylguanidine ((131)I-mIBG) molecular radiotherapy for neuroblastoma remain unclear despite extensive clinical experience. This systematic review aimed to improve understanding of the current data and define uncertainties for future clinical trials. Bibliographic databases were searched for neuroblastoma and (131)I-mIBG. Clinical trials and non-comparative case series of (131)I-mIBG therapy for neuroblastoma were included. Two reviewers assessed papers for inclusion using the title and abstract with consensus achieved by discussion. Data were extracted by one reviewer and checked by a second. Studies with multiple publications were reported as a single study. The searches yielded 1216 citations, of which 51 publications reporting 30 studies met our inclusion criteria. No randomised controlled trials (RCTs) were identified. In two studies (131)I-mIBG had been used as induction therapy and in one study it had been used as consolidation therapy. Twenty-seven studies for relapsed and refractory disease were identified. Publication dates ranged from 1987 to 2012. Total number of patients was 1121 with study sizes ranging from 10 to 164. There was a large amount of heterogeneity between the studies with regard to patient population, treatment schedule and response assessment. Study quality was highly variable. The objective tumour response rate reported in 25 studies ranged from 0% to 75%, mean 32%. We conclude that (131)I-mIBG is an active treatment for neuroblastoma, but its place in the management of neuroblastoma remains unclear. Prospective randomised trials are essential to strengthen the evidence base.

Autologous and allogeneic cellular therapies for high-risk pediatric solid tumors

Since the 1950s, the overall survival of children with cancer has gone from almost zero to approaching 80%. Although there have been notable successes in treating solid tumors such as Wilms tumor, some childhood solid tumors have continued to elude effective therapy. With the use of megatherapy techniques such as tandem transplantation, dose escalation has been pushed to the edge of dose-limiting toxicities, and any further improvements in event-free survival will have to be achieved through novel therapeutic approaches. This article reviews the status of autologous and allogeneic hematopoietic stem cell transplantation (HSCT) for many pediatric solid tumor types. Most of the clinical experience in transplant for pediatric solid tumors is in the autologous setting, so some general principles of autologous HSCT are reviewed. The article then examines HSCT for diseases such as Hodgkin disease, Ewing sarcoma, and neuroblastoma, and the future of cell-based therapies by considering some experimental approaches to cell therapies.

Iodine-131--metaiodobenzylguanidine double infusion with autologous stem-cell rescue for neuroblastoma: a new approaches to neuroblastoma therapy phase I study

PURPOSE

Iodine-131-metaiodobenzylguanidine ((131)I-MIBG) provides targeted radiotherapy with more than 30% response rate in refractory neuroblastoma, but activity infused is limited by radiation safety and hematologic toxicity. The goal was to determine the maximum-tolerated dose of (131)I-MIBG in two consecutive infusions at a 2-week interval, supported by autologous stem-cell rescue (ASCR) 2 weeks after the second dose.

PATIENTS AND METHODS

The (131)I-MIBG dose was escalated using a 3 + 3 phase I trial design, with levels calculated by cumulative red marrow radiation index (RMI) from both infusions. Using dosimetry, the second infusion was adjusted to achieve the target RMI, except at level 4, where the second infusion was capped at 21 mCi/kg.

RESULTS

Twenty-one patients were enrolled onto the study at levels 1 to 4, with 18 patients assessable for toxicity and 20 patients assessable for response. Cumulative (131)I-MIBG given to achieve the target RMI ranged from 22 to 50 mCi/kg, with cumulative RMI of 3.2 to 8.92 Gy. No patient had a dose-limiting toxicity. Reversible grade 3 nonhematologic toxicity occurred in six patients at level 4, establishing the recommended cumulative dose as 36 mCi/kg. The median time to absolute neutrophil count more than 500/microL after ASCR was 13 days (4 to 27 days) and to platelet independence was 17 days (6 to 47 days). Responses included two partial responses, eight mixed responses, three stable disease, and seven progressive disease. Responses by semiquantitative MIBG score occurred in eight patients, soft tissue responses occurred in five of 11 patients, but bone marrow responses occurred in only two of 13 patients.

CONCLUSION

The lack of toxicity with this approach allowed dramatic dose intensification of (131)I-MIBG, with minimal toxicity and promising activity.

Targeted therapy in nuclear medicine—current status and future prospects

In recent years, a number of new developments in targeted therapies using radiolabeled compounds have emerged. New developments and insights in radioiodine treatment of thyroid cancer, treatment of lymphoma and solid tumors with radiolabeled monoclonal antibodies (mAbs), the developments in the application of radiolabeled small receptor-specific molecules such as meta-iodobenzylguanidine and peptides and the position of locoregional treatment in malignant involvement of the liver are reviewed. The introduction of recombinant human thyroid-stimulating hormone and the possibility to enhance iodine uptake with retinoids has changed the radioiodine treatment protocol of patients with thyroid cancer. Introduction of radiolabeled mAbs has provided additional treatment options in patients with malignant lymphoma, while a similar approach proves to be cumbersome in patients with solid tumors. With radiolabeled small molecules that target specific receptors on tumor cells, high radiation doses can be directed to tumors in patients with disseminated disease. Radiolabeled somatostatin derivatives for the treatment of neuroendocrine tumors are the role model for this approach. Locoregional treatment with radiopharmaceuticals of patients with hepatocellular carcinoma or metastases to the liver may be used in inoperable cases, but may also be of benefit in a neo-adjuvant or adjuvant setting. Significant developments in the application of targeted radionuclide therapy have taken place. New treatment modalities have been introduced in the clinic. The concept of combining therapeutic radiopharmaceuticals with other treatment modalities is more extensively explored.

Radiobiology of systemic radiation therapy

Although systemic radionuclide therapy (SRT) is effective as a palliative therapy in patients with metastatic cancer, there has been limited success in expanding patterns of utilization and in bringing novel systemic radiotherapeutic agents to routine clinical use. Although there are many factors that contribute to this situation, we hypothesize that a better understanding of the radiobiology and mechanism of action of SRT will facilitate the development of future compounds and the future designs of prospective clinical trials. If these trials can be rationalized to the biological basis of the therapy, it is likely that the long-term outcome would be enhanced therapeutic efficacy. In this review, we provide perspectives of the current state of low-dose-rate (LDR) radiation research and offer linkages where appropriate with current clinical knowledge. These include the recently described phenomena of low-dose hyper-radiosensitivity-increased radioresistance (LDH-IRR), adaptive responses, and biological bystander effects. Each of these areas require a major reconsideration of existing models for radiation action and an understanding of how this knowledge will integrate into the evolution of clinical SRT practice. Validation of a role in vivo for both LDH-IRR and biological bystander effects in SRT would greatly impact the way we would assess therapeutic response to SRT, the design of clinical trials of novel SRT radiopharmaceuticals, and risk estimates for both therapeutic and diagnostic radiopharmaceuticals. We believe that the current state of research in LDR effects offers a major opportunity to the nuclear medicine community to address the basic science of clinical SRT practice, to use this new knowledge to expand the use and roles of SRT, and to facilitate the introduction of new therapeutic radiopharmaceuticals.

Traitement des tumeurs neuroendocrines par la mIBG et les peptides radiomarqués

Neuroendocrine tumours are a heterogeneous group, characterized by good prognosis, but important disparities of the evolutionary potential. In the aggressive forms, the therapeutic strategies are limited. The metabolic or systemic radiotherapy, using radiolabelled peptides, which can act at the same time on the primary tumour and its metastases, constitutes a tempting therapeutic alternative, currently in evolution. The preliminary results are encouraging; the prospects are related to the development of new radiopharmaceuticals, with the use of other peptide analogues whose applications will overflow the framework of the neuroendocrine tumours.

Phase I dose escalation of iodine-131-metaiodobenzylguanidine with myeloablative chemotherapy and autologous stem-cell transplantation in refractory neuroblastoma: a new approaches to Neuroblastoma Therapy Consortium Study

PURPOSE

To determine the maximum-tolerated dose (MTD) and toxicity of iodine-131-metaiodobenzylguanidine ((131)I-MIBG) with carboplatin, etoposide, melphalan (CEM) and autologous stem-cell transplantation (ASCT) in refractory neuroblastoma.

PATIENTS AND METHODS

Twenty-four children with primary refractory neuroblastoma and no prior ASCT were entered; 22 were assessable for toxicity and response. (131)I-MIBG was administered on day -21, CEM was administered on days -7 to -4, and ASCT was performed on day 0, followed by 13-cis-retinoic acid. (131)I-MIBG was escalated in groups of three to six patients, stratified by corrected glomerular filtration rate (GFR).

RESULTS

The MTD for patients with normal GFR (> or = 100 mL/min/1.73 m2) was 131I-MIBG 12 mCi/kg, carboplatin 1,500 mg/m2, etoposide 1,200 mg/m2, and melphalan 210 mg/m2. In the low-GFR cohort, at the initial dose level using 12 mCi/kg of 131I-MIBG and reduced chemotherapy, one in six patients had dose limiting toxicity (DLT), including veno-occlusive disease (VOD). Three more patients in this group had grade 3 or 4 hepatotoxicity, and two had VOD, without meeting DLT criteria. There was only one death as a result of toxicity among all 24 patients. All assessable patients engrafted, with median time for neutrophils > or = 500/microL of 10 days and median time for platelets > or = 20,000/microL of 26 days. Six of 22 assessable patients had complete or partial response, and 15 patients had mixed response or stable disease. The estimated probability of event-free survival and survival from the day of MIBG infusion for all patients at 3 years was 0.31 +/- 0.10 and 0.58 +/- 0.10, respectively.

CONCLUSION

131I-MIBG with myeloablative chemotherapy is feasible and effective for patients with neuroblastoma exhibiting de novo resistance to chemotherapy.

Feasibility of Dosimetry-Based High-Dose 131I-Meta-Iodobenzylguanidine with Topotecan as a Radiosensitizer in Children with Metastatic Neuroblastoma

INTRODUCTION

(131)I-meta iodobenzylguanidine ((131)I-mIBG) therapy is established palliation for relapsed neuroblastoma. The topoisomerase-1 inhibitor, topotecan, has direct activity against neuroblastoma and acts as a radiation sensitiser. These 2 treatments are synergistic in laboratory studies. Theoretically, the benefit of (131)I-mIBG treatment could be enhanced by dose escalation and combination with topotecan. Haematological support would be necessary to overcome the myelosuppression, which is the dose-limiting toxicity.

AIMS

Firstly, one aim of this study was to establish whether in vivo dosimetry could be used to guide the delivery of a precise total whole-body radiation-absorbed dose of 4 Gy accurately from 2 (131)I-mIBG treatments. Secondly, the other aim of this study was to determine whether it is feasible to combine this treatment with the topotecan in children with metastatic neuroblastoma.

MATERIAL AND METHODS

An activity of (131)I-mIBG (12 mCi/kg, 444 MBq/kg), estimated to give a whole-body absorbed-radiation dose of approximately 2 Gy, was administered on day 1, with topotecan 0.7 mg/m(2) administered daily from days 1-5. In vivo dosimetry was used to calculate a 2nd activity of (131)I-mIBG, to be given on day 15 which would give a total whole-body dose of 4 Gy. A further 5 doses of topotecan were given from days 15-19. The myeloablative effect of this regimen was circumvented by peripheral blood stem cell or bone marrow support.

RESULTS

Eight children with relapsed stage IV neuroblastoma were treated. The treatment was delivered according to protocol in all patients. There were no unanticipated side-effects. Satisfactory haematological reconstitution occurred in all patients. The measured total whole-body radiation-absorbed dose ranged from 3.7 Gy to 4.7 Gy (mean, 4.2 Gy).

CONCLUSIONS

In vivo dosimetry allows for a specified total whole-body radiation dose to be delivered accurately. This schedule of intensification of (131)I-mIBG therapy by dose escalation and radiosensitization with topotecan with a haemopoietic autograft is safe and practicable. This approach should now be tested for efficacy in a phase II clinical trial.

Tumor response and toxicity with multiple infusions of high dose 131I-MIBG for refractory neuroblastoma

BACKGROUND

(131)I Metaiodobenzylguanidine ((131)I-MIBG) is an effective targeted radiotherapeutic for neuroblastoma with response rates greater than 30% in refractory disease. Toxicity is mainly limited to myelosuppression. The aim of this study was to determine the response rate and hematologic toxicity of multiple infusions of (131)I-MIBG.

PROCEDURE

Patients received two to four infusions of (131)I-MIBG at activity levels of 3-19 mCi/kg per infusion. Criteria for subsequent infusions were neutrophil recovery without stem cell support and lack of disease progression after the first infusion.

RESULTS

Sixty-two infusions were administered to 28 patients, with 24 patients receiving two infusions, two patients receiving three infusions, and two patients receiving four infusions. All patients were heavily pre-treated, including 16 with prior myeloablative therapy. Eleven patients (39%) had overall disease response to multiple therapies, including eight patients with measurable responses to each of two or three infusions, and three with a partial response (PR) after the first infusion and stable disease after the second. The main toxicity was myelosuppression, with 78% and 82% of patients requiring platelet transfusion support after the first and second infusion, respectively, while only 50% had grade 4 neutropenia, usually transient. Thirteen patients did not recover platelet transfusion independence after their final MIBG infusion; stem cell support was given in ten patients.

CONCLUSIONS

Multiple therapies with (131)I-MIBG achieved increasing responses, but hematologic toxicity, especially to platelets, was dose limiting. More effective therapy might be given using consecutive doses in rapid succession with early stem cell support.

Scintigraphic response by 123I-metaiodobenzylguanidine scan correlates with event-free survival in high-risk neuroblastoma

PURPOSE

To investigate whether response to induction therapy, evaluated by metaiodobenzylguanadine (MIBG) and bone scintigraphy, correlates with event-free survival (EFS) in children with high-risk neuroblastoma (NB).

PATIENTS AND METHODS

Twenty-nine high-risk NB patients were treated prospectively with an intensive induction regimen and consolidated with three cycles of high-dose therapy with peripheral blood stem-cell rescue. The scintigraphic response was evaluated by MIBG and bone scans using a semi-quantitative scoring system. The prognostic significance of the imaging scores at diagnosis and following induction therapy was evaluated.

RESULTS

A trend associating worse 4-year EFS rates for patients with versus without osteomedullary uptake on MIBG scintigraphs at diagnosis was seen (35% +/- 11% v 80% +/- 18%, respectively; P =.13). Similarly, patients with positive bone scans at diagnosis had worse EFS than those with negative scans, although the difference did not receive statistical significance (34% +/- 10% v 83% +/- 15%, respectively; P =.06). However, significantly worse EFS was observed in patients with a postinduction MIBG score of >/= 3 compared to those with scores of less than 3 (0% v 58% +/- 11%; P =.002). There was no correlation between bone scan scores and outcome following induction therapy.

CONCLUSION

MIBG scores >/= 3 following induction therapy identifies a subset of NB patients who are likely to relapse following three cycles of high-dose therapy with peripheral blood stem-cell rescue, local radiotherapy, and 13-cis-retinoic acid. Alternative therapeutic strategies should be considered for patients with a poor response to induction therapy.

Hematologic Toxicity of High-Dose Iodine-131–Metaiodobenzylguanidine Therapy for Advanced Neuroblastoma

Purpose

Iodine-131–metaiodobenzylguanidine (131I-MIBG) has been shown to be active against refractory neuroblastoma. The primary toxicity of 131I-MIBG is myelosuppression, which might necessitate autologous hematopoietic stem-cell transplantation (AHSCT). The goal of this study was to determine risk factors for myelosuppression and the need for AHSCT after 131I-MIBG treatment.

Patients and Methods

Fifty-three patients with refractory or relapsed neuroblastoma were treated with 18 mCi/kg 131I-MIBG on a phase I/II protocol. The median whole-body radiation dose was 2.92 Gy.

Results

Almost all patients required at least one platelet (96%) or red cell (91%) transfusion and most patients (79%) developed neutropenia (< 0.5 × 103/μL). Patients reached platelet nadir earlier than neutrophil nadir (P < .0001). Earlier platelet nadir correlated with bone marrow tumor, more extensive bone involvement, higher whole-body radiation dose, and longer time from diagnosis to 131I-MIBG therapy (P ≤ .04). In patients who did not require AHSCT, bone marrow disease predicted longer periods of neutropenia and platelet transfusion dependence (P ≤ .03). Nineteen patients (36%) received AHSCT for prolonged myelosuppression. Of patients who received AHSCT, 100% recovered neutrophils, 73% recovered red cells, and 60% recovered platelets. Failure to recover red cells or platelets correlated with higher whole-body radiation dose (P ≤ .04).

Conclusion

These results demonstrate the substantial hematotoxicity associated with high-dose 131I-MIBG therapy, with severe thrombocytopenia an early and nearly universal finding. Bone marrow tumor at time of treatment was the most useful predictor of hematotoxicity, whereas whole-body radiation dose was the most useful predictor of failure to recover platelets after AHSCT.

Biodistribution of post-therapeutic versus diagnostic (131)I-MIBG scans in children with neuroblastoma

BACKGROUND

To evaluate the biodistribution of therapeutic (131)I-metaiodobenzylguanidine (MIBG) and assess the sensitivity of diagnostic versus therapeutic (131)I-MIBG scans to detect metastatic disease.

PROCEDURE

This retrospective study included 44 diagnostic and post-therapy scans (PTS) in 18 children with neuroblastoma treated with (131)I-MIBG (2.0-33.1 GBq). The findings of diagnostic scans (DS) (2.6-44.4 MBq) were compared to those of corresponding PTS.

RESULTS

In terms of biodistribution, the PTS identified (131)I-MIBG activity in one or more patients in the following regions not detected on the DS: nasal mucosa, cerebellum, central brain, adrenals, spleen, kidneys, thyroid, salivary glands, lower halves of the lungs, bladder, bowel, and an incisional scar. Conversely, the DS identified activity in the thorax, heart, kidneys, and bladder each in one patient without being visualized on the PTS. In terms of sensitivity to detect metastatic disease, 210 lesions were seen on the PTS compared to 151 on the DS. The PTS demonstrated sites of disease not evident in the DS in 16 cases.

CONCLUSIONS

The biodistribution of (131)I-MIBG is different using therapeutic doses as compared to pre-therapy doses. (131)I-MIBG imaging following high therapeutic doses often reveals sites of occult metastatic disease that may be clinically relevant.

Targeted radiotherapy with submyeloablative doses of 131I-MIBG is effective for disease palliation in highly refractory neuroblastoma

PURPOSE

Treatment of refractory neuroblastoma remains a significant clinical problem. Targeted radiotherapy with 131I-MIBG has demonstrated antitumor activity in heavily pretreated neuroblastoma patients with recurrent disease. Response rates may be correlated with total radionuclide dose per kilogram body weight delivered, but higher dose levels are associated with protracted grade 4 hematologic toxicity. The optimal method for using single-agent 131I-MIBG for patients with relapsed high-risk neuroblastoma has not been defined. This study was designed to retrospectively determine the clinical response to 131I-MIBG therapy at submyeloablative doses in patients with refractory neuroblastoma and to describe the toxicities.

PATIENTS AND METHODS

A retrospective chart review of 20 patients with neuroblastoma treated with 131I-MIBG at the Children's Hospital of Philadelphia from 1988 to 2000 was performed. Demographic data, 131I-MIBG dose delivered, toxicities, and clinical responses were reviewed.

RESULTS

A median dose of 9.5 mCi/kg of 131I-MIBG was delivered in 32 courses to 20 patients. Three patients were treated in first complete response, and the remaining 17 patients for residual and/or progressive disease. The objective response rate to the first therapy was 31%, and the remaining patients achieved disease stabilization. In addition, 9 of 11 patients with pain at study entry had significant improvement. Disease response was not correlated with 131I-MIBG dose delivered. No unanticipated toxicities were observed.

CONCLUSIONS

Submyeloablative-dose 131I-MIBG is an effective and relatively nontoxic method for neuroblastoma disease palliation. Most patients show subjective improvement in pain and/or performance status. Increased availability and experience with 131I-MIBG therapy would benefit a large number of children with end-stage neuroblastoma and no realistic hope for cure.

Malignant abdominal masses in children: quick guide to evaluation and diagnosis

A palpable mass in the abdomen of a child is a serious finding. In this article the authors present their single-institution experience of how these malignancies present and their distribution by age and diagnosis. The most common abdominal malignancies diagnosed in the pediatric population include neuroblastoma, Wilms' tumor, hepatoblastoma, lymphoma, and germ cell tumors. This article provides the busy general pediatrician with some guidelines of how to proceed after discovering a suspiciousmass.

Novel techniques in the delivery of radiation in pediatric oncology

The field of radiation oncology continues to develop at a rapid pace, due to concurrent progress in high speed computing, improved sensitivity in diagnostic imaging (both anatomic and physiologic), and the introduction of rational new therapeutics built on solid radiobiologic principles. These innovations will become critically important in the field of pediatric oncology, as they will allow for an increased therapeutic ratio in the developing child. Maximizing the benefit of lower dose radiation through the use of radiation modifiers (hypoxic cell sensitizers, signal transduction pathway inhibitors, concurrent chemotherapy), increasing the tolerance of normal tissues (radioprotectors) and tailoring the target area more closely to the desired critical tissues (IMRT, functional simulation with PET and MRS, radiolabeled monoclonal antibodies) will lessen the short and long term toxicity of radiation and increase its effectiveness.

Megatherapy combining I(131) metaiodobenzylguanidine and high-dose chemotherapy with haematopoietic progenitor cell rescue for neuroblastoma

Despite the use of aggressive chemotherapy, stage 4 high risk neuroblastoma still has very poor prognosis which is estimated at 25%. Metabolic radiotherapy with I(131) MIBG appears a feasible option to enhance the effects of chemotherapy. Seventeen patients having MIBG-positive residual disease received 4.1-11.1 mCi/kg of I(131) MIBG 7-10 days before initiating the high-dose chemotherapy cycle consisting of busulphan 16 mg/kg and melphalan 140 mg/m(2) followed by PBSC infusion. We compared the toxicity in these patients to that seen in 15 control subjects with neuroblastoma who underwent a PBSC transplant without MIBG therapy. We observed greater toxic involvement of the gastrointestinal system in children treated with I(131) MIBG: grade 2 or 3 mucositis developed in 13/17 patients treated with I(131) MIBG and in 9/15 treated without it. Grade 1-2 gastrointestinal toxicity occurred in 12/17 children given MIBG and in 5/15 of the controls. One child receiving I(131) MIBG developed transient interstitial pneumonia. Another child who also received I(131) MIBG after PBSC rescue developed fatal pneumonia after the third course of metabolic radiotherapy. Our experience indicates that MIBG can be included in the high-dose chemotherapy regimens followed by PBSC rescue for children with residual neuroblastoma taking up MIBG. Attention should be paid to avoiding lung complications. Prospective studies are needed to demonstrate the real efficacy of this treatment.