To evaluate the safety and efficacy of high-dose [131I]metaiodobenzylguanidine ([131I]MIBG) in the treatment of malignant pheochromocytoma (PHEO) and paraganglioma (PGL).
Fifty patients with metastatic PHEO or PGL, age 10 to 64 years, were treated with [131I]MIBG doses ranging from 492 to 1,160 mCi (median, 12 mCi/kg). Cumulative [131I]MIBG administered ranged from 492 to 3,191 mCi. Autologous hematopoietic stem cells were collected and cryopreserved before treatment with [131I]MIBG greater than 12 mCi/kg or with a total dose greater than 500 mCi. Sixty-nine [131I]MIBG infusions were given, which included infusions to 35 patients treated once and infusions to 15 patients who received two or three treatments. Response was evaluated by [123I]MIBG scans, computed tomography/magnetic resonance imaging, urinary catecholamines/metanephrines, and chromogranin A.
The overall complete response (CR) plus partial response (PR) rate in 49 evaluable patients was 22%. Additionally, 35% of patients achieved a CR or PR in at least one measure of response without progressive disease, and 8% of patients maintained stable disease for greater than 12 months. Thirty-five percent of patients experienced progressive disease within 1 year after therapy. The estimated 5-year overall survival rate was 64%. Toxicities included grades 3 to 4 neutropenia (87%) and thrombocytopenia (83%). Grades 3 to 4 nonhematologic toxicity included acute respiratory distress syndrome (n = 2), bronchiolitis obliterans organizing pneumonia (n = 2), pulmonary embolism (n = 1), fever with neutropenia (n = 7), acute hypertension (n = 10), infection (n = 2), myelodysplastic syndrome (n = 2), and hypogonadism (n = 4).
Although serious toxicity may occur, the survival and response rates achieved with high-dose [131I]MIBG suggest its utility in the management of selected patients with metastatic PHEO and PGL.
Neuroblastoma is the most common pediatric extracranial solid cancer. This tumor is characterized by metaiodobenzylguanidine (MIBG) avidity in 90% of cases, prompting the use of radiolabeled MIBG for targeted radiotherapy in these tumors.
The available English language literature was reviewed for original research investigating in vitro, in vivo, and clinical applications of radiolabeled MIBG for neuroblastoma.
MIBG is actively transported into neuroblastoma cells by the norepinephrine transporter. Preclinical studies demonstrate substantial activity of radiolabeled MIBG in neuroblastoma models, with 131I-MIBG showing enhanced activity in larger tumors compared to 125I-MIBG. Clinical studies of 131I-MIBG in patients with relapsed or refractory neuroblastoma have identified myelosuppression as the main dose-limiting toxicity, necessitating stem cell reinfusion at higher doses. Most studies report a response rate of 30–40% with 131I-MIBG in this population. More recent studies have focused on the use of 131I-MIBG in combination with chemotherapy or myeloablative regimens.
131I-MIBG is an active agent for the treatment of patients with neuroblastoma. Future studies will need to define the optimal role of this targeted radiopharmaceutical in the therapy of this disease.
Metaiodobenzylguanidine; neuroblastoma; pediatric; radionuclide
Children with relapsed neuroblastoma have poor survival. It is crucial to have a reliable method for evaluating functional response to new therapies. In this study, we compared two functional imaging modalities for neuroblastoma: metaiodobenzylguanidine (MIBG) scan for uptake by the norepinephrine transporter and [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) uptake for glucose metabolic activity.
Patients and Methods
Patients enrolled onto a phase I study of sequential infusion of iodine-131 (131I) MIBG (NANT-2000-01) were eligible for inclusion if they had concomitant FDG-PET and MIBG scans. 131I-MIBG therapy was administered on days 0 and 14. For each patient, we compared all lesions identified on concomitant FDG-PET and MIBG scans and gave scans a semiquantitative score.
The overall concordance of positive lesions on concomitant MIBG and FDG-PET scans was 39.6% when examining the 139 unique anatomic lesions. MIBG imaging was significantly more sensitive than FDG-PET overall and for the detection of bone lesions (P < .001). There was a trend for increased sensitivity of FDG-PET for detection of soft tissue lesions. Both modalities showed similar improvement in number of lesions identified from day 0 to day 56 scan and in semiquantitative scores that correlated with overall response. FDG-PET scans became completely negative more often than MIBG scans after treatment.
MIBG scan is significantly more sensitive for individual lesion detection in relapsed neuroblastoma than FDG-PET, though FDG-PET can sometimes play a complementary role, particularly in soft tissue lesions. Complete response by FDG-PET metabolic evaluation did not always correlate with complete response by MIBG uptake.
Adolescent and adult patients with neuroblastoma appear to have a more indolent disease course but a lower survival than their younger counterparts. The majority of neuroblastoma tumors specifically accumulate the radiolabeled norepinephrine analogue 131I-metaiodobenzylguanidine (MIBG). 131I-MIBG has therefore become increasingly used as targeted radiotherapy for relapsed or refractory neuroblastoma. The aim of this study was to characterize the toxicity and activity of this therapy in older patients.
We performed a retrospective analysis of 39 consecutive patients ages 10 years and older with relapsed or refractory neuroblastoma who were treated with 131I-MIBG monotherapy at UCSF under Phase I, Phase II, and compassionate access protocols.
Sixteen patients were ≥18 years old at MIBG treatment initiation, whereas twenty-three were 10–17 years old. The median cumulative administered dose of 131I-MIBG was 17.8 mCi/kg. The majority of treatments led to grade 3 or 4 hematologic toxicities which were similar in frequency among age strata. Three patients subsequently developed hematologic malignancy or myelodysplasia. The overall rate of complete plus partial response was 46%. Patients ≥18 years old at time of first MIBG treatment had a significantly higher response rate compared to patients 10–17 years old (56% vs 39%, p=0.023). Median overall survival was 23 months with a trend toward longer overall survival for the ≥18 year old subgroup (p = 0.12).
Our findings suggest that 131I-MIBG is a highly effective salvage agent for adolescents and adults with neuroblastoma.
neuroblastoma; adult; adolescent; MIBG; radiopharmaceutical
131I-Metaiodobenzylguanidine (131I-MIBG) provides targeted radiotherapy for children with neuroblastoma, a malignancy of the sympathetic nervous system. Dissociated radioactive iodide may concentrate in the thyroid, and MIBG is concentrated in the liver after MIBG therapy. The aim of our study was to analyze the effects of 131I-MIBG therapy on thyroid and liver function.
Pre and post therapy thyroid and liver functions were reviewed in a total of 194 neuroblastoma patients treated with 131I-MIBG therapy. The cumulative incidence over time was estimated for both thyroid and liver toxicities. The relationship to cumulative dose/kg, number of treatments, time from treatment to follow-up, sex, and patient age was examined.
In patients who presented with Grade 0 or Grade 1 thyroid toxicity at baseline, 12±4% experienced onset or worsening to Grade 2 hypothyroidism and one patient developed Grade 2 hyperthyroidism by two years after 131I-MIBG therapy. At two years post 131I-MIBG therapy, 76±4% patients experienced onset or worsening of hepatic toxicity to any grade, and 23±5% experienced onset of or worsening to Grade 3 or 4 liver toxicity. Liver toxicity usually was transient asymptomatic transaminase elevation, frequently confounded by disease progression and other therapies.
The prophylactic regimen of potassium iodide and potassium perchlorate with 131I-MIBG therapy resulted in a low rate of significant hypothyroidism. Liver abnormalities following 131I-MIBG therapy were primarily reversible and did not result in late toxicity. 131I-MIBG therapy is a promising treatment for children with relapsed neuroblastoma with a relatively low rate of symptomatic thyroid or hepatic dysfunction.
Neuroblastoma; 131I-MIBG; Hypothyroidism
[124I]m-iodobenzylguanidine (124I-mIBG) provides a quantitative tool for pretherapy tumor imaging and dosimetry when performed before [131I]m-iodobenzylguanidine (131I-mIBG) targeted radionuclide therapy of neuroblastoma. 124I (T1/2=4.2d) has a comparable half-life to that of 131I (T1/2=8.02d), and can be imaged by PET for accurate quantification of the radiotracer distribution. We estimated expected radiation dose in tumors from 131I-mIBG therapy using 124I-mIBG microPET/CT imaging data in a murine xenograft model of neuroblastoma transduced to express high levels of the human norepinephrine transporter (hNET).
In order to enhance mIBG uptake for in vivo imaging and therapy, NB 1691-luciferase (NB1691) human neuroblastoma cells were engineered to express high levels of hNET protein by lentiviral transduction (NB1691-hNET). Both NB1691 and NB1691-hNET cells were implanted subcutaneously and into renal capsules in athymic mice. 124I-mIBG (4.2–6.5 MBq) was administered intravenously for microPET/CT imaging at 5 time points over 95 hours (0.5, 3–5, 24, 48, and 93–95 h median time points). In vivo biodistribution data in normal organs, tumors, and whole-body were collected from reconstructed PET images corrected for photon attenuation using the CT-based attenuation map. Organ and tumor dosimetry were determined for 124I-mIBG. Dose estimates for 131I-mIBG were made, assuming the same in vivo biodistribution as 124I-mIBG.
All NB1691-hNET tumors had significant uptake and retention of 124I-mIBG, whereas unmodified NB1691 tumors did not demonstrate quantifiable mIBG uptake in vivo, despite in vitro uptake. 124I-mIBG with microPET/CT provided an accurate 3-dimensional tool for estimating the radiation dose that would be delivered with 131I-mIBG therapy. For example, in our model system, we estimated that the administration of 131I-mIBG in the range of 52.8 – 206 MBq would deliver 20 Gy to tumors.
The overexpression of hNET was found to be critical for 124I-mIBG uptake and retention in vivo. The quantitative 124I-mIBG PET/CT is a promising new tool to predict tumor radiation doses with 131I-mIBG therapy of neuroblastoma. This methodology may be applied to tumor dosimetry of 131I-mIBG therapy in human subjects using 124I-mIBG pretherapy PET/CT data.
neuroblastoma; m-iodobenzylguanidine; iodine-124; iodine-131; PET/CT; animal model; radiation dosimetry
The radiopharmaceutical 131I-metaiodobenzylguanidine (131I-MIBG) is used for the targeted radiotherapy of noradrenaline transporter (NAT)-expressing neuroblastoma. Enhancement of 131I-MIBG's efficacy is achieved by combination with the topoisomerase I inhibitor topotecan - currently being evaluated clinically. Proteasome activity affords resistance of tumour cells to radiation and topoisomerase inhibitors. Therefore, the proteasome inhibitor bortezomib was evaluated with respect to its cytotoxic potency as a single agent and in combination with 131I-MIBG and topotecan. Since elevated levels of reactive oxygen species (ROS) are induced by bortezomib, the role of ROS in tumour cell kill was determined following treatment with bortezomib or the alternative proteasome inhibitor, MG132.
Clonogenic assay and growth of tumour xenografts were used to investigate the effects of proteasome inhibitors alone or in combination with radiation treatment. Synergistic interactions in vitro were evaluated by combination index analysis. The dependency of proteasome inhibitor-induced clonogenic kill on ROS generation was assessed using antioxidants.
Bortezomib, in the dose range 1 to 30 nM, decreased clonogenic survival of both SK-N-BE(2c) and UVW/NAT cells, and this was prevented by antioxidants. It also acted as a sensitizer in vitro when administered with X-radiation, with 131I-MIBG, or with 131I-MIBG and topotecan. Moreover, bortezomib enhanced the delay of the growth of human tumour xenografts in athymic mice when administered in combination with 131I-MIBG and topotecan. MG132 and bortezomib had similar radiosensitizing potency, but only bortezomib-induced cytotoxicity was ROS-dependent.
Proteasome inhibition shows promise for the treatment of neuroblastoma in combination with 131I-MIBG and topotecan. Since the cytotoxicity of MG132, unlike that of bortezomib, was not ROS-dependent, the latter proteasome inhibitor may have a favourable toxicity profile in normal tissues.
Bortezomib; Proteasome; 131I-metaiodobenzylguanidine; Neuroblastoma; Radiosensitizer
In the present study, we investigated the anticancer effects of the mitochondrial inhibitors, metaiodobenzylguanidine (MIBG), metformin and phenformin. 131I-MIBG has been used for scintigraphic detection and the targeted radiotherapy of neuroblastoma (NB), a pediatric malignancy. Non-radiolabeled MIBG has been reported to be cytotoxic to NB cells in vitro and in vivo. However, the mechanisms behind its growth suppressive effects have not yet been fully elucidated. Metformin and phenformin are diabetes medications that are being considered in anticancer therapeutics. We investigated the anticancer mechanisms of action of MIBG and metformin in NB. Our data revealed that both drugs suppressed NB cell growth and that the combination drug treatment was more potent. MIBG reduced MYCN and MYC expression in MYCN-amplified and non-MYCN-amplified NB cells in a dose- and time-dependent manner. Metformin was less effective than MIBG in destabilizing MYC/MYCN. The treatment of NB cells with metformin or MIBG resulted in an increased expression of genes encoding biomarkers for favorable outcome in NB [(ephrin (EFN)B2, EFNB3, EPH receptor B6 (EPHB6), neurotrophic tyrosine kinase, receptor, type 1 (NTRK1), CD44 and Myc-interacting zinc finger protein (MIZ-1)] and tumor suppressor genes [(early growth response 1 (EGR1), EPH receptor A2 (EPHA2), growth arrest and DNA-damage-inducible, beta (GADD45B), neuregulin 1 (NRG1), TP53 apoptosis effector (PERP) and sel-1 suppressor of lin-12-like (C. elegans) (SEL1L)]. Accordingly, metformin and MIBG augmented histone H3 acetylation in these cells. Phenformin also exhibited histone modification and was more effective than metformin in destabilizing MYC/MYCN in NB cells. Our data suggest that the destabilization of MYC/MYCN by MIBG, metformin and phenformin and their effects on histone modification are important mechanisms underlying their anticancer effects.
In the treatment of patients with high-risk neuroblastoma, different doses of 131I-metaiodobenzylguanidine (131I-MIBG) are administered at different time points during treatment. Toxicity, mainly haematological (thrombocytopenia), from 131I-MIBG therapy is known to occur in extensively chemotherapy pretreated neuroblastoma patients. Up to now, acute toxicity from 131I-MIBG as initial treatment has never been studied in a large cohort. The aim of this retrospective study was to document acute toxicity related to upfront 131I-MIBG.
All neuroblastoma patients (stages 1–4 and 4S) treated upfront with 131I-MIBG at the Emma Children’s Hospital, Academic Medical Centre (1992 – 2008) were included in this retrospective analysis. The acute toxicity (during therapy) and short-term toxicity (1st month following therapy) of the first two 131I-MIBG therapies were studied.
Of 66 patients (34 boys, 32 girls; median age 2.2 years, range 0.1 – 9.4 years), 49 had stage 4 disease, 5 stage 4S, 6 stage 3, 1 stage 2 and 5 stage 1. The median first dose was 441 MBq/kg (range 157 – 804 MBq/kg). The median second dose was 328 MBq/kg (range 113 – 727 MBq/kg). The most frequently observed symptoms were nausea and vomiting (21 %, maximum grade II). The main toxicity was grade IV haematological, occurring only in stage 4 patients, after the first and second 131I-MIBG therapies: anaemia (5 % and 4 %, respectively), leucocytopenia (3 % and 4 %) and thrombocytopenia (2 % and 4 %). No stem cell rescue was needed.
The main acute toxicity observed was haematological followed by nausea and vomiting. One patient developed posterior reversible encephalopathy syndrome during 131I-MIBG therapy, possibly related to 131I-MIBG. We consider 131I-MIBG therapy to be a safe treatment modality.
Electronic supplementary material
The online version of this article (doi:10.1007/s00259-013-2510-z) contains supplementary material, which is available to authorized users.
Neuroblastoma; 131I-MIBG therapy; Acute toxicity
In patients with localised neuroblastoma without adverse genetic aberrations, observational treatment is justified. Therapy is required when organ or respiratory functions have become compromised. As the outcome is good, side effects of treatment should be prevented. The aim of this retrospective study was to evaluate response and outcome in patients treated with 131I-metaiodobenzylguanidine (MIBG) for unresectable localised neuroblastoma, with compromised organ functions.
Patients with localised neuroblastoma [median age 1.6 years (0–5.5 years)] diagnosed between 1989 and 2008 were included in this retrospective study (n = 21). Primary tumours were unresectable and there was a compromised organ or respiratory function. Diagnosis and staging were performed according to the International Neuroblastoma Staging System. Fixed doses of 131I-MIBG therapy (50–200 mCi) were given. The median number of infusions was two (range one to seven). Response was graded according to the International Neuroblastoma Response Criteria.
Of the 21 patients, 14 did not need any chemotherapy. Patients were treated with 131I-MIBG therapy and, in most cases, with additional surgery and/or chemotherapy. Sixteen achieved complete response (CR), three very good partial response (VGPR), one partial response (PR) and one progressive disease (PD). Two patients died of PD after having achieved CR initially and due to surgical complications a few months after resection. Ten-year overall survival and event-free survival were 90.5 %. The median follow-up was 8.5 years (range 0.4–19.6 years).
131I-MIBG therapy is an effective treatment modality for unresectable localised neuroblastoma with compromised organ functions. However, this was a small and heterogeneous cohort and further studies are needed.
Electronic supplementary material
The online version of this article (doi:10.1007/s00259-013-2455-2) contains supplementary material, which is available to authorized users.
Neuroblastoma; 131I-MIBG therapy; Localised; Unresectable
Neuroblastoma, the most common extra- cranial solid tumor in children, is derived from neural crest cells. Nearly half of patients present with metastatic disease, and have 5-year EFS of less than 50%. New approaches with targeted therapy may improve efficacy without increased toxicity. The current review will evaluate three promising targeted therapies, including 131I-metaiodobenzylguanidine (MIBG), a radiopharmaceutical taken up by the human norepinephrine transporter expressed in 90% of neuroblastomas, immunotherapy with monoclonal antibodies targeting the GD2 ganglioside, expressed on 98% of neuroblastoma cells, and inhibitors of ALK, a tyrosine kinase which is mutated or amplified in approximately 10% of neuroblastoma and expressed on the surface of most neuroblastoma cells. Early phase trials have confirmed the activity of 131I-MIBG in relapsed neuroblastoma, with response rates of about 30%, but the technical aspects of administration of large amounts of radioactivity in young children and the limited access have hindered incorporation into treatment of newly diagnosed patients. Anti-GD2 antibodies have also demonstrated activity in relapsed disease, and a recent phase III randomized trial showed a significant improvement in event-free survival for patients receiving chimeric anti-GD2 (ch14.18) combined with cytokines and isotretinoin after myeloablative consolidation therapy. A recently approved small molecule inhibitor of ALK has promising pre-clinical activity for neuroblastoma, and is currently in phase I and II trials. This is the first agent directed to a specific mutation in neuroblastoma, and marks a new step toward personalized therapy for neuroblastoma. Further clinical development of targeted treatments offers new hope for children with neuroblastoma.
Iodine-131-metaiodiobenzylguanidine (131I-MIBG) therapy combined with allogeneic cord blood stem cell transplantation (SCT) was used to treat a 4-year-old girl with recurrent neuroblastoma. The patient experienced relapse 2 years after receiving first-line therapies, which included chemotherapy, surgical resection, irradiation, and autologous peripheral SCT. Although 131I-MIBG treatment did not achieve complete remission, the size of the tumor was reduced after treatment. Based on our findings, we suggest that 131I-MIBG treatment with myeloablative allogeneic SCT should be considered as first-line therapy for high-risk neuroblastoma patients when possible.
MIBG; Neuroblastoma; Allogeneic cord blood stem cell transplantation
Mathematical models have predicted that targeted radiotherapy of neuroblastoma with metaiodobenzylguanidine (mIBG) is less likely to cure small rather than large micrometastases if 131I is the conjugated radionuclide. This study uses multicellular tumour spheroids as an in vitro model to test the hypothesis that smaller tumours of sub-millimetre dimensions are relatively resistant to 131I-mIBG. Spheroids of the human neuroblastoma cell line SK-N-BE(2c), either 250 microns or 400 microns diameter, were incubated with 131I-mIBG at concentrations of up to 6.0 MBq ml-1. Using both regrowth delay and spheroid 'cure' as endpoints, the greater vulnerability of larger spheroids was confirmed. From this in vitro result we conclude that when used in vivo 131I-mIBG may spare smaller micrometastases. Therefore, either a radionuclide such as 211At which emits a shorter path length radiation should be conjugated to mIBG, or targeted radiotherapy should be combined with a treatment such as total body irradiation, the efficacy of which is not reduced in smaller tumours.
Relapse-free survival (RFS) is a powerful measure of treatment efficacy. We describe the sensitivity of standard surveillance studies for detecting relapse of neuroblastoma (NB).
Patients and Methods
The patients were in complete/very good partial remission of high-risk NB; routine monitoring revealed asymptomatic and, therefore, unsuspected relapses in 113 patients, whereas 41 patients had symptoms prompting urgent evaluations. Assessments every 2 to 4 months included computed tomography, iodine-131–metaiodobenzylguanidine 131I-MIBG; through November 1999) or iodine-123–metaiodobenzylguanidine (123I-MIBG) scan, urine catecholamines, and bone marrow (BM) histology. Bone scan was routine through 2002.
123I-MIBG scan was the most reliable study for revealing unsuspected relapse; it had an 82% detection rate, which was superior to the rates with 131I-MIBG scan (64%; P = .1), bone scan (36%; P < .001), and BM histology (34%; P < .001). Among asymptomatic patients, 123I-MIBG scan was the sole positive study indicating relapse in 25 (27%) of 91 patients compared with one (4.5%) of 22 patients for 131I-MIBG scan (P = .04) and 0% to 6% of patients for each of the other studies (P < .001). Patients whose monitoring included 123I-MIBG scan were significantly less likely than patients monitored by 131I-MIBG scan to have an extensive osteomedullary relapse and had a significantly longer survival from relapse (P < .001) and from diagnosis (P = .002). They also had significantly longer survival than patients with symptomatic relapses (P = .002).
123I-MIBG scan is essential for valid estimation of the duration of RFS of patients with high-risk NB. Without monitoring that includes 123I-MIBG scan, caution should be used when comparing RFS between institutions and protocols.
Radioimmunotherapy (RIT) has been used to treat relapsed/refractory CD20+ Non-Hodgkin lymphoma (NHL). Myeloablative anti-CD20 RIT followed by autologous stem cell infusion (ASCT) enables high radiation doses to lymphoma sites. We performed a phase I/II trial to assess feasibility and survival.
Twenty-three patients with relapsed/refractory NHL without complete remission (CR) to salvage chemotherapy were enrolled to evaluate RIT with Iodine-131 labelled rituximab (131I-rituximab) in a myeloablative setting. Biodistribution and dosimetric studies were performed to determine 131I activity required to induce a total body dose of 21-27Gy to critical organs. In 6/23 patients RIT was combined with high-dose chemotherapy. 8/23 patients received a sequential high-dose chemotherapy with a second ASCT. The median follow-up is 9.5 years.
6.956-19.425GBq of 131I was delivered to achieve the limiting organ dose to lungs or kidneys. No grade III/IV non-hematologic toxicity was seen with RIT alone. Significant grade III/IV toxicity (mucositis, fever, infection, one therapy related death) was observed in patients treated with RIT combined with high-dose chemotherapy. The overall response rate was 87% (64% CR). The median progression-free (PFS) and overall survival (OS) is 47.5 and 101.5 months. An international prognostic index score >1 was predictive for OS.
Myeloablative RIT with 131I-rituximab followed by ASCT is feasible, well-tolerated and effective in high risk CD20+ NHL. Combination of RIT and high-dose chemotherapy increased toxicity significantly. Long-term results for PFS and OS are encouraging.
Non-Hodgkin lymphoma; Radioimmunotherapy; CD20; High-dose chemotherapy; Autologous stem cell transplantation
This phase II study was conducted to determine the response rate associated with use of irinotecan and temozolomide for children with relapsed/refractory neuroblastoma.
Patients and Methods
Patients with relapsed/refractory neuroblastoma measurable by cross-sectional imaging (stratum 1) or assessable by bone marrow aspirate/biopsy or metaiodobenzylguanidine (MIBG) scan (stratum 2) received irinotecan (10 mg/m2/dose 5 days a week for 2 weeks) and temozolomide (100 mg/m2/dose for 5 days) every 3 weeks. Response was assessed after three and six courses using International Neuroblastoma Response Criteria. Of the first 25 evaluable patients on a given stratum, five or more patients with complete or partial responses were required to conclude that further study would be merited.
Fifty-five eligible patients were enrolled. The objective response rate was 15%. Fourteen patients (50%) on stratum 1 and 15 patients (56%) on stratum 2 had stable disease. Objective responses were observed in three of the first 25 evaluable patients on stratum 1 and five of the first 25 evaluable patients on stratum 2. Less than 6% of patients experienced ≥ grade 3 diarrhea. Although neutropenia was observed, less than 10% of patients developed evidence of infection while neutropenic.
The combination of irinotecan and temozolomide was well tolerated. The objective response rate of 19% in stratum 2 suggests that this combination may be effective for patients with neuroblastoma detectable by MIBG or marrow analysis. Although fewer objective responses were observed in patients with disease measurable by computed tomography/magnetic resonance imaging, patients in both strata seem to have derived clinical benefit from this therapy.
Biological and clinical observations suggest that initial marked reduction of resistant clones may be critical in any attempt to improve long-term results in advanced neuroblastoma (NB). The aim of this pilot study is to determine short-term toxicity and efficacy of a new therapeutic model based on the simultaneous use of multiple drug chemotherapy and specific irradiation using 131-I-MIBG. The study population consisted of 21 patients, from 1 to 8 years of age with good 131-I-MIBG uptake. 16 extensively pre-treated patients with refractory or relapsed disease were divided into 2 groups. In Group 1 (9 patients) the basic chemotherapy regimen consisted in cisplatin at the dose of 20 mg/m2i.v. per day infused over 2 h, for 4 consecutive days; on day 4 Cy 2 g/m2i.v. was administered over 2 h followed by Mesna. Group 2 (7 patients) was treated with basic chemotherapeutic regimen plus VP16 and Vincristine. VP16 at the dose of 50 mg/m2i.v. per day was administered as a 24 h infusion on days 1–3; Vincristine 1.5 mg/m2i.v. was administered on days 1 and 6. On day 10 a single dose of 131-I-MIBG (200 mCi) with a high specific activity (>1.1 GBq/mg) was administered to both Groups by i.v. infusion over 4–6 hours. A further 5 patients were treated at diagnosis: 2 with the same regimen as Group 1 and 3 with the same as Group 2. The severity of toxicity was graded according to World Health Organization (WHO) criteria. Assessment of tumour response was monitored 4–6 weeks after the beginning of combined therapy (CO-TH). Response was defined according to INSS (International Neuroblastoma Staging System) criteria. No extra-medullary toxicity was observed in any patient. Haematological toxicity was the only toxicity observed and seemed mainly related to chemotherapy. Myelosuppression was mild in the 5 patients treated at diagnosis. No serious infections or significant bleeding problems were observed. In the 16 resistant patients, 12 PR, 1 mixed response and 3 SD were obtained. In the 5 patients treated at diagnosis 2 PR, 1 CR and 2 VGPR were observed. No alteration in 131-I-MIBG uptake was observed after the chemotherapy preceding radio-metabolic treatment. The therapeutic results of this pilot regimen of CO-TH resulted in a high percentage of major response after only a single course in both resistant patients and patients treated at diagnosis. Because of the minimal toxicity observed in patients studied at diagnosis so far, there is room for gradual intensification of the treatment. It is to be hoped that this suggested novel approach may represent an important route of investigation to improve final outcome in patients with advanced NB. © 2001 Cancer Research Campaign http://www.bjcancer.com
neuroblastoma; combined therapy; 131-I-metaiodobenzylguanidine
Incomplete response to therapy may compromise the outcome of children with advanced neuroblastoma. In an attempt to improve tumour response we incorporated 131I-metaiodobenzylguanidine (131I-MIBG) in the treatment regimens of selected stage 3 and stage 4 patients. Between 1986 and 1997, 43 neuroblastoma patients older than 1 year at diagnosis, 13 with stage 3 (group A) and 30 with stage 4 disease (group B) who had completed the first-line protocol without achieving complete response entered in this study. 131I-MIBG dose/course ranged from 2.5 to 5.5 Gbq (median, 3.7). The number of courses ranged from 1 to 5 (median 3) depending on the tumour response and toxicity. The most common acute side-effect was thrombocytopenia. Later side-effects included severe interstitial pneumonia in one patient, acute myeloid leukaemia in two, reduced thyroid reserve in 21. Complete response was documented in one stage 4 patient, partial response in 12 (two stage 3, 10 stage 4), mixed or no response in 25 (ten stage 3, 15 stage 4) and disease progression in five (one stage 3, four stage 4) Twenty-four patients (12/13 stage 3, 12/30 stage 4) are alive at 22–153 months (median, 59) from diagnosis. 131I-MIBG therapy may increase the cure rate of stage 3 and improve the response of stage 4 neuroblastoma patients with residual disease after first-line therapy. A larger number of patients should be treated to confirm these results but logistic problems hamper prospective and coordinated studies. Long-term toxicity can be severe. © 1999 Cancer Research Campaign
neuroblastoma; radiometabolic therapy; 131I-metaiodobenzylguanidine
Histone deacetylase (HDAC) inhibition causes transcriptional activation or repression of several genes that in turn can influence the biodistribution of other chemotherapeutic agents. Here, we hypothesize that the combination of vorinostat, a HDAC inhibitor, with 131I-metaiodobenzylguanidine (MIBG) would lead to preferential accumulation of the latter in neuroblastoma (NB) tumors via increased expression of the human norepinephrine transporter (NET).
In vitro and in vivo experiments examined the effect of vorinostat on the expression of NET, an uptake transporter for 131I-MIBG. Human NB cell lines (Kelly and SH-SY-5Y) and NB1691luc mouse xenografts were employed. The upregulated NET protein was characterized for its effect on 123I-MIBG biodistribution.
Preincubation of NB cell lines, Kelly and SH-SY-5Y, with vorinostat caused dose-dependent increases in NET mRNA and protein levels. Accompanying this was a corresponding dose-dependent increase in MIBG uptake in NB cell lines. Four-fold and 2.5 fold increases were observed in Kelly and SH-SY-5Y cells, respectively, pre-treated with vorinostat in comparison to untreated cells. Similarly, NB xenografts, created by intravenous tail vein injection of NB1691-luc, and harvested from nude mice livers treated with vorinostat (150 mg/kg i.p.) showed substantial increases in NET protein expression. Maximal effect of vorinostat pretreatment in NB xenografts on 123I-MIBG biodistribution was observed in tumors that exhibited enhanced uptake in vorinostat treated (0.062 ± 0.011 μCi/(mg tissue-dose injected)) versus untreated mice (0.022 ± 0.003 μCi/(mg tissue-dose injected); p < 0.05).
The results of our study provide preclinical evidence that vorinostat treatment can enhance NB therapy with 131I-MIBG.
norepinephrine transporter; MIBG; Vorinostat; histone deacetylase inhibitor; neuroblastoma xenograft; biodistribution
131I-metaiodobenzylguanidine (131I-MIBG) is a licensed palliative treatment for patients with metastatic neuroendocrine tumours. We have retrospectively assessed the consequences of 131I-MIBG therapy in 48 patients (30 gastroenteropancreatic, 6 pulmonary, 12 unknown primary site) with metastatic neuroendocrine tumours attending Royal Liverpool University Hospital between 1996 and 2006. Mean age at diagnosis was 57.6 years (range 34–81). 131I-MIBG was administered on 88 occasions (mean 1.8 treatments, range 1–4). Twenty-nine patients had biochemical markers measured before and after 131I-MIBG, of whom 11 (36.7%) showed >50% reduction in levels post-therapy. Forty patients had radiological investigations performed after 131I-MIBG, of whom 11(27.5%) showed reduction in tumour size post-therapy. Twenty-seven (56.3%) patients reported improved symptoms after 131I-MIBG therapy. Kaplan–Meier analysis showed significantly increased survival (P=0.01) from the date of first 131I-MIBG in patients who reported symptomatic benefit from therapy. Patients with biochemical and radiological responses did not show any statistically significant alteration in survival compared to non-responders. Eleven (22.9%) patients required hospitalisation as a consequence of complications, mostly due to mild bone marrow suppression. 131I-MIBG therefore improved symptoms in more than half of the patients with metastatic neuroendocrine tumours and survival was increased in those patients who reported a symptomatic response to therapy.
Carcinoid; neuroendocrine; radionuclide; 131I-MIBG
Sinonasal paragangliomas are very uncommon neuroendocrine tumors that can present as skull base lesions. Functional paragangliomas are exceedingly rare. They can be associated with genetic mutations that have been associated with increased risk of head and neck paragangliomas. We present a case of a rare functioning sinonasal paraganglioma of the skull base in a patient with distant history of prior abdominal paragangliomas. The patient underwent subtotal endoscopic resection of the skull base lesion limited by carotid encasement of the tumor. They were treated with postoperative adjuvant radiation and therapeutic metaiodobenzylguanidine (MIBG) therapy. Genetic testing revealed succinate dehydrogenase B (SDHB) mutation. Skull base paragangliomas are rare tumors that may preclude complete surgical resection. 131Iodine-MIBG can be used as adjuvant therapy in postoperative external beam radiation and in MIBG avid tumors. Long-term follow-up is needed given locally aggressive nature of these tumors, especially for patients with history of genetic mutations such as SDHB mutations as recurrent paragangliomas may develop.
head and neck paraganglioma; sinonasal paraganglioma; endoscopic skull base resection; succinate dehydrogenase mutation
The efficacy of tandem high-dose chemotherapy and autologous stem cell rescue (HDCT/ASCR) was investigated in patients with high-risk neuroblastoma. Patients over 1 yr of age who were newly diagnosed with stage 4 neuroblastoma from January 2000 to December 2005 were enrolled in The Korean Society of Pediatric Hematology-Oncology registry. All patients who were assigned to receive HDCT/ASCR at diagnosis were retrospectively analyzed to investigate the efficacy of single or tandem HDCT/ASCR. Seventy and 71 patients were assigned to receive single or tandem HDCT/ASCR at diagnosis. Fifty-seven and 59 patients in the single or tandem HDCT group underwent single or tandem HDCT/ASCR as scheduled. Twenty-four and 38 patients in the single or tandem HDCT group remained event free with a median follow-up of 56 (24-88) months. When the survival rate was analyzed according to intent-to-treat at diagnosis, the probability of the 5-yr event-free survival±95% confidence intervals was higher in the tandem HDCT group than in the single HDCT group (51.2±12.4% vs. 31.3±11.5%, P=0.030). The results of the present study demonstrate that the tandem HDCT/ASCR strategy is significantly better than the single HDCT/ASCR strategy for improved survival in the treatment of high-risk neuroblastoma patients.
Neuroblastoma; High-dose Chemotherapy; Transplantation, Autologous
Radioiodinated meta-iodobenzylguanidine (MIBG) is one of the important radiopharmaceuticals in Nuclear Medicine. [123/131I] MIBG is used for imaging of Adrenal medulla, studying heart sympathetic nerves, treatment of pheochromacytoma and neuroblastoma. For clinical application, radioiodinated MIBG is prepared through isotopic exchange method, which includes replacement of radioactive iodine in a nucleophilic substitution reaction with cold iodine (127I). The unlabelled MIBG hemisulfate is synthesized by the procedure described by Wieland et al. (1980). The availability of a more practical and cost-effective procedure for MIBG preparation encouraged us to study the MIBG synthesis methods. In this study the preparation of MIBG through different methods were evaluated and a new method, which is one step, simple and cost-effective is introduced. The method has ability to be scaled up for production of unlabelled MIBG.
Meta-iodobenzylguanidine; Neuroendocrine tumors; Sympathetic neurons; Radioiodinated MIBG
[131I]meta-iodobenzylguanidine ([131I]MIBG) provides a means of selectively delivering radiation to neuroblastoma cells and is a promising addition to the range of agents used to treat neuroblastoma. As MIBG is now being incorporated into multimodal approaches to therapy, important questions arise about the appropriate scheduling and sequencing of the various agents employed. As the ability of neuroblastoma cells to actively accumulate MIBG is crucial to the success of this therapy, the effect of chemotherapeutic agents on this uptake capacity needs to be investigated. We report here our initial findings on the effect of cisplatin pretreatment on the neuroblastoma cell line SK-N-BE (2c). After treating these cells with therapeutically relevant concentrations of cisplatin (2 microM and 20 microM), a stimulation in uptake of [131I]MIBG was observed. Reverse transcription-polymerase chain reaction (RT-PCR) analysis demonstrated that this effect was due to increased expression of the noradrenaline transporter. These results suggest that appropriate scheduling of cisplatin and [131I]MIBG may lead to an increase in tumour uptake of this radiopharmaceutical with consequent increases in radiation dose to the tumour.
Indirect effects may contribute to the efficacy of radiotherapy by sterilizing malignant cells that are not directly irradiated. However, little is known of the influence of indirect effects in targeted radionuclide treatment. We compared γ-radiation-induced bystander effects with those resulting from exposure to three radiohaloanalogues of meta-iodoben-zylguanidine (MIBG): [131I]MIBG (low linear energy transfer (LET) α-emitter), [123I]MIBG (high LET Auger electron emitter), and meta-[211At]astatobenzylguanidine ([211At]MABG) (high LET α-emitter). Cells exposed to media from γ-irradiated cells exhibited a dose-dependent reduction in survival fraction at low dosage and a plateau in cell kill at > 2 Gy. Cells treated with media from [131I]MIBG demonstrated a dose-response relationship with respect to clonogenic cell death and no annihilation of this effect at high radiopharmaceutical dosage. In contrast, cells receiving media from cultures treated with [211At]MABG or [123I]MIBG exhibited dose-dependent toxicity at low dose but elimination of cytotoxicity with increasing radiation dose (i.e. U-shaped survival curves). Therefore radionuclides emitting high LET radiation may elicit toxic or protective effects on neighboring untargeted cells at low and high dose respectively. We conclude that radiophar-maceutical-induced bystander effects may depend on LET and be distinct from those elicited by conventional radiotherapy.
Radiopharmaceutical-induced bystander effect