Therapeutic possibilities of 131I-MIBG in metastatic carcinoid tumors--preliminary report

The poor results of traditional therapy in advanced carcinoid tumors and the well-proven uptake of 131I-MIBG shown by some of these tumors induced us to attempt a radiometabolic approach. We selected for the treatment 5 patients (3 men and 2 women) who showed progression of disease, a fairly good uptake of 131I-MIBG with severe related symptoms, and a poor response to traditional therapy. A cumulative radioactivity of 5.5-29.6 GBq was given. Acute side effects after 131I-MIBG administration or late radiation-induced damages were not observed. Symptoms increased during the first 2-4 weeks in 2 patients: in one of these relief was achieved with drugs. Results concerning objective remission of the disease were unsatisfactory. In contrast, definite improvement of symptoms was shown in 2 of 5 patients, resulting in a better quality of life.     

Treatment of neuroendocrine tumours in adults with 131I-MIBG therapy

This is a retrospective review of 131I-MIBG therapy for metastatic neuroendocrine tumours in 25 adult patients. The tumours comprised 17 carcinoids, six paragangliomas, one somatostatinoma and one intestinal smooth muscle sarcoma. All patients (age range 28-84 years) had stage IV disease and a positive diagnostic 123I-MIBG scan. Patients received 11.1 GBq (300 mCi) of 131I-MIBG given in three cycles at 3-monthly intervals. The mean cumulative dose was 27.7 GBq (751 mCi). Symptomatic response was observed in 80%, hormonal response in 55% and tumour response in 48% (WHO criteria). Of the 25 patients, 40% are still under follow-up. Death was due to disease progression in all except one. The median survival time was 48 months from diagnosis of metastatic disease, and 17 months from the last 131I-MIBG therapy. The 5-year survival rate was 59% (95% confidence interval, 34%-78%). There was no statistical difference in survival between previously treated (chemo/radiotherapy) and treatment-naive patients. Side-effects were minimal and commonly include nausea (in the first 24 h) and a transient fall in platelet count. 131I-MIBG provides a good therapeutic response in patients with metastatic neuro-endocrine tumours.     

Sequelae and survivorship in patients treated with 131I-MIBG therapy

Background:

¹³¹I-meta-iodobenzylguanidine (¹³¹I-MIBG) has been in therapeutic use since 1980s. Newer treatment modalities are emerging for neuroendocrine tumours (NETs) and chromaffin cell tumours (CCTs), but many of these do not yet have adequate long-term follow-up to determine their longer term efficacy and sequelae.

Methods:

Fifty-eight patients with metastatic NETs and CCTs who had received ¹³¹I-MIBG therapy between 2000 and 2011 were analysed. Survival and any long-term haematological or renal sequelae were investigated.

Results:

In the NET group, the overall median survival and median survival following the diagnosis of metastatic disease was 124 months. The median survival following the commencement of ¹³¹I-MIBG was 66 months. For the CCT group, median survival had not been reached. The 5-year survival from diagnosis and following the diagnosis of metastatic disease was 67% and 67.5% for NETs and CCTs, respectively. The 5-year survival following the commencement of ¹³¹I-MIBG therapy was 68%. Thirty-two patients had long-term haematological sequelae: 5 of these 32 patients developed haematological malignancies. Two patients developed a mild deterioration in renal function.

Conclusion:

Long follow up of ¹³¹I-MIBG therapy reveals a noteable rate of bone marrow toxicities and malignancy and long term review of all patients receiving radionuclide therapies is recommended.     

Treatment of metastatic para-aortic paraganglioma by surgery, radiotherapy and I-131 mIBG

A patient with a malignant, functioning, aortico-sympathetic paraganglioma and a solitary bone metastasis causing paraplegia was treated by spinal decompression, irradiation of the metastasis, surgical excision of the primary tumour and systemic I-131 meta-iodobenzyl-guanidine (mIBG). Sixteen months after treatment there was no clinical, radiological or biochemical evidence of residual disease and neurological function was restored. The case supports the use of combined treatment incorporating mIBG in patients with metastatic neuroendocrine tumours which demonstrate mIBG uptake.     

(131)I-MIBG radionuclide therapy is safe and cost-effective in the control of symptoms of the carcinoid syndrome.

BACKGROUND: The standard treatment used to control the symptoms of carcinoid syndrome (CS) involves subcutaneous injections of the somatostatin analogue octreotide. This is expensive (US $8000--16,000 per year), and treatment may be for many years. The aim of this study was to evaluate the efficacy and cost-effectiveness of our experience over the last 5 years with 1-131-labelled metaiodobenzylguanidine (MIBG) radionuclide therapy in the palliation of patients with CS. METHODS: A consecutive series of 20 symptomatic patients (referred between 1994 and 1999) with CS were evaluated. Fifteen of them underwent(123)I-MIBG scanning. Of the 13 patients with significant tracer uptake in metastatic deposits compared to background, 12 underwent a course of therapeutic(131)I-MIBG (one patient refused). Symptoms, biochemical markers, CT scans, follow-up(123)I-MIBG scans, and the requirement for octreotide were used to assess outcome of treatment. Costs of(131)I-MIBG and octreotide treatments were compared. RESULTS: MIBG treatment was well tolerated in all with only transient side-effects. Ten patients showed a measurable clinical improvement. Seven had a complete clinical response. The mean duration of response was 15.4 months. Octreotide was not required or was reduced in eight patients. Treatment with(131)I-MIBG resulted in a saving of US $1000 per patient, with effective symptom control, when compared to octreotide. CONCLUSION: 1-131 MIBG therapy is a safe and cost-effective therapeutic option to successfully control symptoms in patients with carcinoid syndrome. Copyright Harcourt Publishers Limited.     

PET scan assessment of chemotherapy response in metastatic paraganglioma

Paragangliomas are indolent tumors that arise from the chief cells of the paraganglia in the head and neck, mediastinum, and retroperitoneal regions. Less than 10% of paragangliomas metastasize. Paragangliomas are known to regress slowly and usually partially after radiation therapy, which has been attributed to the development of fibrosis within the abundant vascular elements of the tumor. Positron emission tomography (PET) scanning was used to monitor a 33-year-old woman with recurrent paraganglioma of the carotid body with lung and bone metastases before and after chemotherapy with cyclophosphamide, doxorubicin (Adriamycin), and dacarbazine. The patient derived clinical benefit from chemotherapy, with marked improvement of her systemic and respiratory symptoms, improvement of cancer-related anemia, and normalization of chromogranin A levels. A response was demonstrated on PET scan with decreased [18F] fluoro-2-deoxy-d-glucose uptake after chemotherapy, but no significant changes were detected on serial computed tomography (CT) scans. The patient has remained free of disease progression 24 months after chemotherapy completion. It is suggested that metabolic imaging with PET scans is superior to anatomical imaging with CT scans for the monitoring of patients with paragangliomas.     

Assessment of the efficacy and toxicity of (131)I-metaiodobenzylguanidine therapy for metastatic neuroendocrine tumours

(131)I-metaiodobenzylguanidine ((131)I-MIBG) is a licensed palliative treatment for patients with metastatic neuroendocrine tumours. We have retrospectively assessed the consequences of (131)I-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). (131)I-MIBG was administered on 88 occasions (mean 1.8 treatments, range 1-4). Twenty-nine patients had biochemical markers measured before and after (131)I-MIBG, of whom 11 (36.7%) showed >50% reduction in levels post-therapy. Forty patients had radiological investigations performed after (131)I-MIBG, of whom 11(27.5%) showed reduction in tumour size post-therapy. Twenty-seven (56.3%) patients reported improved symptoms after (131)I-MIBG therapy. Kaplan-Meier analysis showed significantly increased survival (P=0.01) from the date of first (131)I-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. (131)I-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.     

Repeated high-dose chemotherapy followed by purged autologous bone marrow transplantation as consolidation therapy in metastatic neuroblastoma

Among 62 children over 1 year of age at diagnosis, who were treated for stage IV neuroblastoma, 33 entered complete remission (CR) or good partial remission (GPR) after conventional therapy and received high-dose chemotherapy (HDC) with in vitro purged autologous bone marrow transplantation (ABMT) as consolidation therapy. The HDC was a combination of carmustine (BCNU), teniposide (VM-26), and melphalan. Thirty-three patients received one course of this regimen, and 18 received two courses. At present, 16 of the 33 grafted patients are alive in continuous CR, with a median follow-up of 28 months. Toxicity of this regimen was tolerable, principally marked by bone marrow depression and gastrointestinal (GI) tract complications. Four complication-related deaths were observed. Relapse post-ABMT occurred most often in the bone marrow. Under this treatment, actuarial disease-free survival is improved compared with that observed under conventional therapy.     

SDHB mutations are associated with response to temozolomide in patients with metastatic pheochromocytoma or paraganglioma

Cyclophosphamide–dacarbazine–vincristine regimen is recommended for the treatment of malignant pheochromocytoma and paraganglioma (MPP); however, dacarbazine is the only recognized active drug in neuroendocrine tumours. We investigated the therapeutic benefit of temozolomide (TMZ), an oral alternative to dacarbazine, in patients with MPP. This is a retrospective study of consecutive patients with documented progressive MPP. We examined the correlation between Succinate dehydrogenase B (SDHB) mutation and O(6)‐methylguanine‐DNA methyltransferase (MGMT) promoter methylation and MGMT expression in the French nation‐wide independent cohort of 190 pheochromocytomas or paragangliomas (PP). Progression‐free survival (PFS) according to RECIST 1.1 and PERCIST 1.0 criteria was the primary end point. Fifteen consecutive patients with MPP were enrolled; ten (67%) carried a mutation in SDHB. The mean dose intensity of TMZ was 172 mg/m²/d for 5 days every 28 days. Median PFS was 13.3 months after a median follow‐up of 35 months. There were five partial responses (33%), seven stable (47%) and three progressive diseases (20%). Grade 3 toxicities were lymphopenia in two patients and hypertension in one. Partial responses were observed only in patients with mutation in SDHB. MGMT immunohistochemistry was negative in tumour samples from four patients who responded to treatment. SDHB germline mutation was associated with hypermethylation of the MGMT promoter and low expression of MGMT in 190 samples of the French nation‐wide independent cohort. This study demonstrates that TMZ is an effective antitumour agent in patients with SDHB‐related MPP. The silencing of MGMT expression as a consequence of MGMT promoter hypermethylation in SDHB‐mutated tumours may explain this finding.     

Radiation therapy of choriocarcinoma metastatic to the brain

Brain irradiation for metastases was performed in 3 cases of choriocarcinoma of pregnancy and 1 patient with testicular choriocarcinoma of embryonal origin. Treatment failed in 2 cases due to tumor advancement, while the other 2 patients showed marked response. Early diagnosis and proper treatment of intracranial metastases may significantly increase survival.     

[131I]-Metaiodobenzylguanidine in the treatment of metastatic neuroblastoma

Ten children with stage III or IV neuroblastoma that had either relapsed or was refractory were treated with [131I]-metaiodobenzylguanidine (MIBG) from 1984 to 1986. The total dose ranged from 4,365 to 21,900 MBq and was given in one to five courses. Two patients achieved a complete remission (CR), two, a partial remission (PR), and three, an arrest of the disease. Pharmacological studies showed that 93% of detectable radioactivity was attributable to MIBG at the beginning of the infusion. However, by the end of the infusion this had decreased to 88%. The terminal half-life of MIBG was 37.0 h, whereas that of non-MIBG-bound iodine was 71.6 h. Therefore, the radioactivity-time product of non-MIBG-bound 131I was much higher than that of MIBG. Dosimetric studies showed a mean level of absorbed radiation for the total body of 160 microGy/MBq, a liver irradiation of 540 microGy/MBq and a mean tumour radiation of 10,500 microGy/MBq.     

Contribution of androgen deprivation therapy to elevated osteoclast activity in men with metastatic prostate cancer.

PURPOSE: Biochemical markers of both osteoblast and osteoclast activity are elevated in men with osteoblastic metastases from prostate cancer. Androgen deprivation therapy (ADT), the mainstay of therapy for advanced prostate cancer, increases markers of osteoblast and osteoclast activity, even in the absence of bone metastases. Little is known about the relative contributions of ADT and skeletal metastases to elevated bone turnover in men with prostate cancer. EXPERIMENTAL DESIGN: To evaluate the relative contributions of ADT and skeletal metastases to osteoblast and osteoclast activity, we performed a cross-sectional study in three groups of men with advanced prostate cancer: (a) hormone-na?ve men without bone metastases; (b) castrate men without bone metastases; and (c) castrate men with bone metastases. The primary study end points were serum levels of bone-specific alkaline phosphatase (BSAP), a marker of osteoblast activity, and N-telopeptide (NTX), a marker of osteoclast activity. RESULTS: Serum levels of both BSAP and NTX were significantly higher in groups of castrate men (groups 2 and 3) than in hormone-na?ve men (group 1; P < 0.01 for all comparisons). Among castrate men, serum BSAP was significantly higher in men with bone metastases than in men without bone metastases (P = 0.01). In contrast, serum levels of NTX were similar in groups 2 and 3 (P = 0.33). CONCLUSIONS: The unintended effects of ADT on the skeleton are sufficient to explain increased osteoclast activity in castrate men with bone metastases. These results may have important implications for the optimal timing and schedule of osteoclast-targeted therapy in men with advanced prostate cancer.     

Carboplatin in the treatment of metastatic carcinoid tumours and paraganglioma: a phase II study

A total of 13 patients with metastatic carcinoid tumour, paraganglioma, or unclassified "apudoma" were treated with single-agent carboplatin at a dose of 400 mg/m2 given by intravenous infusion every 4 weeks, on the basis that this new agent shows high activity against small-cell lung cancer that also has "apudoma" characteristics. No objective tumour responses were seen. Overall, 2 patients achieved minor regression, 4/9 (44%) showed a reduction of greater than 50% in urinary 5-HIAA excretion and 8/13 (62%) reported symptomatic improvement. Treatment was well tolerated, with neutropenia and thrombocytopenia being the main toxicities. Carboplatin, like other cytotoxic agents, does not appear to have major activity against these tumours, although further studies in patients with metastatic paraganglioma are warranted.     

Predicting the response to targeted therapy in metastatic colorectal cancer

Colorectal cancer is the second most common cause of cancer‐related deaths in Australia. The median survival of metastatic colorectal cancer remains poor, but novel targeted therapies offer promise in improving patient outcomes. However, it is vital to identify which patients with metastatic colorectal cancer will benefit from targeted therapy. Predictive biomarkers offer significant benefit by refining the treatment population to a subgroup that has a greater prospect of benefit from therapy. This provides efficacy benefits, but also minimizes the overall toxicity and cost of treatment. In this review we examine current knowledge regarding predictive biomarkers for targeted agents in metastatic colorectal cancer, with a particular focus on emerging biomarkers such as oncogenic mutations. We also highlight issues that require further exploration in the quest for personalized therapy in metastatic colorectal cancer.     

Somatic cell fusion as a source of genetic rearrangement leading to metastatic variants

Summary Tumor cell populations displaying metastatic properties often have higher gene dosage than their less malignant progenitor tumors, as shown by increased ploidy levels, chromosome duplication and gene amplification. The acquisition by tumor cells of high chromosome numbers may be due to endoreduplication or somatic hybridization either between tumor cells or between tumor and host cells. All such mechanisms increase genetic variability and instability in tumor cells since they trigger a polyploidization-segregation cycle. Among the wide variety of segregants which may emerge from high-ploidy cells, variants with increased malignancy can be positively selected in vivo. Evidence for in vivo fusion of tumor and normal host cells has been reported in different tumor systems. However the attainment by tumor-host hybrids of a higher degree of malignancy has only been observed following substantial chromosome segregation. The involvement of a cell of bone marrow origin as preferential host partner in the fusion process has been proved both by studies on tumor-host hybrids in bone marrow radiation chimeras and in vitro hybridization experiments between non-metastatic tumors and normal lymphoreticular cells which have led to the establishment of metastatic variants. Several different segregational mechanisms may bring about homozygosity or hemizygosity of recessive alleles in tumor-host hybrids, leading to their expression. The marked chromosome dynamics of tumor-host hybrids are also responsible for extensive chromosome rearrangements. At the molecular level these may represent mechanisms causing altered oncogene activity. The activation of new oncogenes by transposition or amplification as well as the amplification of previously activated oncogenes are the mechanisms most likely to be responsible for transition from low to high malignancy, occurring through ploidy changes, such as those produced by somatic mating.     

Prediction of therapy tumor-absorbed dose estimates in I-131 radioimmunotherapy using tracer data via a mixed-model fit to time activity

Abstract Background: For individualized treatment planning in radioimmunotherapy (RIT), correlations must be established between tracer-predicted and therapy-delivered absorbed doses. The focus of this work was to investigate this correlation for tumors. Methods: The study analyzed 57 tumors in 19 follicular lymphoma patients treated with I-131 tositumomab and imaged with SPECT/CT multiple times after tracer and therapy administrations. Instead of the typical least-squares fit to a single tumor's measured time-activity data, estimation was accomplished via a biexponential mixed model in which the curves from multiple subjects were jointly estimated. The tumor-absorbed dose estimates were determined by patient-specific Monte Carlo calculation. Results: The mixed model gave realistic tumor time-activity fits that showed the expected uptake and clearance phases even with noisy data or missing time points. Correlation between tracer and therapy tumor-residence times (r=0.98; p<0.0001) and correlation between tracer-predicted and therapy-delivered mean tumor-absorbed doses (r=0.86; p<0.0001) were very high. The predicted and delivered absorbed doses were within±25% (or within±75 cGy) for 80% of tumors. Conclusions: The mixed-model approach is feasible for fitting tumor time-activity data in RIT treatment planning when individual least-squares fitting is not possible due to inadequate sampling points. The good correlation between predicted and delivered tumor doses demonstrates the potential of using a pretherapy tracer study for tumor dosimetry-based treatment planning in RIT.