High frequency of bone/bone marrow involvement in advanced medullary thyroid cancer

Medullary Thyroid Carcinoma: An Update on Imaging

Medullary thyroid carcinoma (MTC), arising from the parafollicular C cells of the thyroid, accounts for 1–2% of thyroid cancers. MTC is frequently aggressive and metastasizes to cervical and mediastinal lymph nodes, lungs, liver, and bones. Although a number of new imaging modalities for directing the management of oncologic patients evolved over the last two decades, the clinical application of these novel techniques is limited in MTC. In this article, we review the biology and molecular aspects of MTC as an important background for the use of current imaging modalities and approaches for this tumor. We discuss the modern and currently available imaging techniques—advanced magnetic resonance imaging (MRI)-based techniques such as whole-body MRI, dynamic contrast-enhanced (DCE) technique, diffusion-weighted imaging (DWI), positron emission tomography/computed tomography (PET/CT) with 18F-FDOPA and 18F-FDG, and integrated positron emission tomography/magnetic resonance (PET/MR) hybrid imaging—for primary as well as metastatic MTC tumor, including its metastatic spread to lymph nodes and the most common sites of distant metastases: lungs, liver, and bones.

Bone and Calcified Soft Tissue Metastases of Medullary Thyroid Carcinoma Better Characterized on 18F-Fluoride PET/CT than on 68Ga-Dotatate PET/CT

Herein, we report a case of a 19-year-old man with multiple endocrine neoplasia type 2B (MEN2B) and medullary thyroid carcinoma (MTC) diagnosed when he was 12 years of age. The patient had previously undergone total thyroidectomy, cervical radiotherapy, and chemotherapy. He progressed with known bone, pulmonary, and lymph node metastases and was scanned with ¹⁸F-fluoride (¹⁸F-NaF) and ⁶⁸Ga-dotatate whole-body positron emission tomography/computed tomography (PET/CT) for metastatic disease monitoring. We found that the MTC bone metastases and soft tissue calcified metastases were better characterized on ¹⁸F-NaF PET/CT than on ⁶⁸Ga-dotatate PET/CT. This case illustrates that the ¹⁸F-NaF PET/CT could be helpful not only to the detection of bone metastases but also to the detection of calcified soft tissue metastases in patients with MTC.

The role of hepatic trans-arterial chemoembolization in metastatic medullary thyroid carcinoma: a specialist center experience and review of the literature

BACKGROUND

Liver metastases are relatively common in patients with metastatic medullary thyroid carcinoma (MTC), carrying a negative impact on disease prognosis. The options for selective therapy of liver metastases in MTC patients are limited to catheter-guided procedures such as trans-arterial chemoembolization (TACE). Data regarding the effectiveness and safety of this procedure in MTC are limited.

AIM

To explore the clinical outcome, survival and safety profile of TACE for liver metastases in a group of MTC patients.

METHODS

Retrospective case series of patients treated at a single tertiary University Medical Center from 2005 to 2015.

RESULTS

Seven consecutive patients (mean age 64.5 ± 10.9 years, 5 females) with histologically confirmed MTC with liver metastases were included. Metastatic involvement of the liver was less than 50% of the liver volume in all patients. The median size of the largest liver lesion was 40 ± 6.9 mm. The patients underwent in total 20 sessions of TACE. Clinical improvement as well as tumor response (PR) were observed in all patients. The median time to tumor progression was 38 months (range 8-126). Three patients were still alive at the end of the follow-up period (a median overall survival rate of 57 ± 44 months).

CONCLUSION

TACE in MTC patients with hepatic metastases is usually well tolerated and induces both clinical improvement and tumor response for prolonged periods of time in the majority of patients. This therapeutic option should always be considered, irrespective of the presence of extrahepatic metastasis.

Unusual gastric mucosal infiltration by a medullary thyroid carcinoma: a case report

Background

Medullary thyroid carcinoma accounts for approximately 1 to 2 % of all thyroid carcinoma cases. The most common route of dissemination is to locoregional lymph nodes. Distant metastases commonly affect bones, lungs, and liver. We present a case of a white woman with a 25-year history of medullary thyroid carcinoma on multiple medications including tyrosine kinase inhibitor therapy for the last 11 months, who exhibited unusual diffuse infiltration of advanced stage medullary thyroid carcinoma to her gastric mucosa.

Case presentation

A 53-year-old white woman presented with increasing fatigue, loss of appetite, and severe epigastric pain radiating to her back. She had a history of medullary thyroid carcinoma (pT2pN1b), diagnosed 25 years ago and treated by complete thyroidectomy and repeated bilateral cervical lymph node dissection. Medical therapy included octreotide 20 mg every 4 weeks, which was switched to the tyrosine kinase inhibitor vandetanib 300 mg/day 11 months ago when computed tomography scanning revealed progressive mediastinal lymph node and diffuse and symptomatic pulmonary metastases. Of note, she demonstrated macroscopically stable pulmonary and mediastinal lymph node metastases; however, her calcitonin serum levels dramatically increased. Computed tomography scanning revealed a single new intrahepatic lesion (4 mm) as well as multiple (>10) new supraclavicular lesions suggestive of medullary thyroid carcinoma progress. As proven by gastric biopsy and immunohistochemical evaluation, her epigastric pain was explained by a diffuse infiltration of her gastric mucosa by metastatic medullary thyroid carcinoma. Subsequently, she rapidly deteriorated and died.

Conclusions

The current case report shows for the first time an unusual metastatic infiltration of the gastric mucosa by medullary thyroid carcinoma. When treating these patients, it is important to include this differential diagnosis during follow-up.

Electronic supplementary material

The online version of this article (doi:10.1186/s13256-016-0981-9) contains supplementary material, which is available to authorized users.

Epidemiology and Clinical Presentation of Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor originating from the thyroid C cells producing mainly calcitonin (CTN) used as tumor marker. MTC occurs either sporadic (75%) or in a hereditary form (multiple endocrine neoplasia type 2, MEN2), due to germline mutations in the RET proto-oncogene. The discovery of an MTC in a patient has several diagnostic implications involving a specific strategy: preoperative evaluation of the tumor marker CTN and the extent of the disease, classification of MTC as sporadic or hereditary by DNA testing, and screening for associated endocrinopathies in hereditary MTC. Elevated CTN is a highly sensitive and specific tumor marker for diagnosis and follow-up of MTC. CTN is directly related to the tumor mass. In patients with nodular thyroid disease, diagnosis of MTC could be made by CTN determination as an indicator of tumor burden in conjunction with fine-needle aspiration. Patients with confirmed sporadic or hereditary MTC should have a total thyroidectomy and depending on the preoperative CTN value and the extent of disease additional dissection of the lymph nodes in the central and lateral neck compartment. In MEN 2 patients diagnosed by screening, the time of prophylactic thyroidectomy depends on RET mutation and CTN level.

Recurrent spinal metastasis of a sporadic medullary carcinoma of the thyroid after radiation therapy: a case report and review of the literature

Sporadic Medullary Carcinoma of the Thyroid is a relatively uncommon entity and at the time of diagnosis, most already present loco-regional metastasis. Therapy should be aggressive to reduce recurrence and mortality. Follow-up period should continue lifelong and should also include calcium/pentagastrin infusion test, as well as 6-month interval diagnostic imaging.

A pretargeting system for tumor PET imaging and radioimmunotherapy

Labeled antibodies, as well as their fragments and antibody-derived recombinant constructs, have long been proposed as general vectors to target radionuclides to tumor lesions for imaging and therapy. They have indeed shown promise in both imaging and therapeutic applications, but they have not fulfilled the original expectations of achieving sufficient image contrast for tumor detection or sufficient radiation dose delivered to tumors for therapy. Pretargeting was originally developed for tumor immunoscintigraphy. It was assumed that directly-radiolabled antibodies could be replaced by an unlabeled immunoconjugate capable of binding both a tumor-specific antigen and a small molecular weight molecule. The small molecular weight molecule would carry the radioactive payload and would be injected after the bispecific immunoconjugate. It has been demonstrated that this approach does allow for both antibody-specific recognition and fast clearance of the radioactive molecule, thus resulting in improved tumor-to-normal tissue contrast ratios. It was subsequently shown that pretargeting also held promise for tumor therapy, translating improved tumor-to-normal tissue contrast ratios into more specific delivery of absorbed radiation doses. Many technical approaches have been proposed to implement pretargeting, and two have been extensively documented. One is based on the avidin-biotin system, and the other on bispecific antibodies binding a tumor-specific antigen and a hapten. Both have been studied in preclinical models, as well as in several clinical studies, and have shown improved targeting efficiency. This article reviews the historical and recent preclinical and clinical advances in the use of bispecific-antibody-based pretargeting for radioimmunodetection and radioimmunotherapy of cancer. The results of recent evaluation of pretargeting in PET imaging also are discussed.

Long-Term Follow-up in Medullary Thyroid Carcinoma

After surgery, patients with medullary thyroid carcinoma (MTC) should be assessed regarding the presence of residual disease, the localization of metastases, and the identification of progressive disease. Postoperatively, patients with MTC are staged to separate those at low risk from those at high risk of recurrence. The TNM staging system is based on tumor size, extra-thyroidal invasion, nodal metastasis, and distant spread of cancer. In addition, the number of lymph-node metastases, the number of compartments involved, and the postoperative calcitonin (CTN) and carcinoembryonic antigen (CEA) levels should be documented. The postoperative normalization of the serum CTN level is associated with a favorable outcome. When patients have basal serum CTN levels less than 150 pg/ml after a thyroidectomy, any persistent or recurrent disease is nearly always confined to lymph nodes in the neck. When the postoperative serum CTN level exceeds 150 pg/ml, patients should be evaluated with imaging procedures, including computed tomography (CT) of the neck and chest, contrast-enhanced magnetic resonance imaging (MRI) and ultrasound (US) of the liver, bone scintigraphy, MRI of the bone, and positron emission tomography (PET)/CT. One can estimate the growth rate of MTC metastases by quantifying increases in tumor size over time from sequential imaging studies analyzed with response evaluation criteria in solid tumors (RECIST), and by determining the tumor marker doubling time from sequential measures of serum CTN or CEA levels over multiple time points. One of the main challenges remains to find effective adjuvant and palliative options for patients with metastatic disease. Patients with persistent or recurrent MTC localized to the neck following thyroidectomy are candidates for neck operations, depending on the tumor extension. Once metastases appear, the clinician must decide which patients require therapy. This requires a balance between the (often) slow rate of tumor progression, which is associated with a good quality of life, and the limited efficacy and potential toxicities of local and systemic therapies. Considering that metastatic MTC is incurable, the management goals are to provide loco-regional disease control, palliate symptoms of hormonal excess, such as diarrhea, palliate symptomatic metastases, like pain or bone fracture, and control metastases that threaten life, such as bronchial obstruction or spinal cord compression. This can be achieved with palliative surgery, external beam radiation therapy (EBRT), or systemic therapy with tyrosine kinase inhibitor (TKI).

Medullary Thyroid Carcinoma: Imaging

Imaging plays an important role in early detection and staging of medullary thyroid carcinoma (MTC) as well as in follow-up to localize early recurrence. MTC is a rare, calcitonin-secreting thyroid malignancy often diagnosed by ultrasound and calcitonin screening as part of the routine workup for any thyroid nodule. If calcitonin is elevated, imaging studies are needed for preoperative staging, which dictates surgical management. This can be done by ultrasound of the neck and abdomen. Computed tomography (CT) or magnetic resonance imaging (MRI) studies for more distant disease are done preoperatively if calcitonin levels are higher than 500 pg/ml. Neither FDG-PET/CT nor F-DOPA-PET/CT are used routinely for preoperative staging but may contribute in doubtful individual cases. Postoperative elevated calcitonin is related to persistence or recurrence of MTC. Imaging studies to localize tumor tissue during postoperative follow-up include ultrasound, CT, MRI as well as PET studies. They should be used wisely, however, since treatment consequences are often limited, and even patients with persistent disease may survive long enough to accumulate significant radiation doses. Imaging studies are also useful for diagnosis of associated components of the hereditary MTC such as pheochromocytoma and primary hyperparathyroidism (pHPT).

Surgical Treatment of Medullary Thyroid Cancer

Medullary thyroid cancer (MTC) can vary in tumor biology and progression. The most important indicator of distant metastases, determining clinical outcome, is lymph node metastasis to the neck and mediastinum. Surgical cure is within reach in node-negative tumors or node-positive tumors with fewer than 10 lymph node metastases. From a surgical point of view, compartment-oriented lymph node dissection, clearing gross, and occult metastases are important for locoregional tumor control. The discovery of missense germline mutations in the RET proto-oncogene and the close genotype-phenotype correlation in hereditary MTC promoted the worldwide breakthrough of prophylactic thyroidectomy. The best approach to hereditary MTC affords the DNA-based/biochemical concept, which is geared at limiting prophylactic surgery to total thyroidectomy at minimal surgical morbidity before the tumor can spread beyond the thyroid capsule. To improve outcome, routine calcitonin screening in nodular thyroid disease and DNA-based screening of the offspring in RET families are effective interventions.

Diagnóstico, tratamento e seguimento do carcinoma medular de tireoide: recomendações do Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia

Introdução O carcinoma medular de tireoide (CMT) origina-se das células parafoliculares da tireoide e corresponde a 3-4% das neoplasias malignas da glândula. Aproximadamente 25% dos casos de CMT são hereditários e decorrentes de mutações ativadoras no proto-oncogene RET (REarranged during Transfection). O CMT é uma neoplasia de curso indolente, com taxas de sobrevida dependentes do estádio tumoral ao diagnóstico. Este artigo descreve diretrizes baseadas em evidências clínicas para o diagnóstico, tratamento e seguimento do CMT. Objetivo O presente consenso, elaborado por especialistas brasileiros e patrocinado pelo Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia, visa abordar o diagnóstico, tratamento e seguimento dos pacientes com CMT, de acordo com as evidências mais recentes da literatura. Materiais e métodos: Após estruturação das questões clínicas, foi realizada busca das evidências disponíveis na literatura, inicialmente na base de dados do MedLine-PubMed e posteriormente nas bases Embase e SciELO – Lilacs. A força das evidências, avaliada pelo sistema de classificação de Oxford, foi estabelecida a partir do desenho de estudo utilizado, considerando-se a melhor evidência disponível para cada questão. Resultados Foram definidas 11 questões sobre o diagnóstico, 8 sobre o tratamento cirúrgico e 13 questões abordando o seguimento do CMT, totalizando 32 recomendações. Como um todo, o artigo aborda o diagnóstico clínico e molecular, o tratamento cirúrgico inicial, o manejo pós-operatório e as opções terapêuticas para a doença metastática. Conclusões O diagnóstico de CMT deve ser suspeitado na presença de nódulo tireoidiano e história familiar de CMT e/ou associação com feocromocitoma, hiperparatireoidismo e/ou fenótipo sindrômico característico, como ganglioneuromatose e habitus marfanoides. A punção aspirativa por agulha fina do nódulo, a dosagem de calcitonina sérica e o exame anatomopatológico podem contribuir na confirmação do diagnóstico. A cirurgia é o único tratamento que oferece a possibilidade de cura. As opções de tratamento da doença metastática ainda são limitadas e restritas ao controle da doença. Uma avaliação pós-cirúrgica criteriosa para a identificação de doença residual ou recorrente é fundamental para definir o seguimento e a conduta terapêutica subsequente.

Current update on medullary thyroid carcinoma

OBJECTIVE

This article will review the multimodality imaging spectrum of medullary thyroid carcinoma (MTC) with an emphasis on anatomic and functional imaging. Recent advances in the molecular cytogenetics of this tumor and the impact on diagnosis, prognosis, and development of novel targeted therapy will be discussed.

CONCLUSION

MTC is a neuroendocrine tumor with unique clinicopathologic and radiologic features compared with other thyroid malignancies. Imaging plays an important role in the optimal management of this malignancy.

Current understanding and management of medullary thyroid cancer

Medullary thyroid cancer (MTC) typically accounts for 3%-4% of all thyroid cancers. Although the majority of MTCs are sporadic, 20% of cases are hereditary. Hereditary MTC can be found in multiple endocrine neoplasia 2A or 2B or as part of familial MTC based on a specific germline mutation in the RET proto-oncogene. This article discusses the current approaches available for the diagnosis, evaluation, and management of patients and their family members with suspected MTC. The disease is predominantly managed surgically and typically requires a total thyroidectomy and lymph node dissection. A review of recent guidelines on the extent and timing of surgical excision is discussed. There are not very many effective systemic treatment options for MTC, but several emerging therapeutic targets have promise.

Improvement of radioimmunotherapy using pretargeting

During the past two decades, considerable research has been devoted to radionuclide therapy using radiolabeled monoclonal antibodies and receptor binding agents. Conventional radioimmunotherapy (RIT) is now an established and important tool in the treatment of hematologic malignancies such as Non-Hodgkin lymphoma. For solid malignancies, the efficacy of RIT has not been as successful due to lower radiosensitivity, difficult penetration of the antibody into the tumor, and potential excessive radiation to normal tissues. Innovative approaches have been developed in order to enhance tumor absorbed dose while limiting toxicity to overcome the different limitations due to the tumor and host characteristics. Pretargeting techniques (pRIT) are a promising approach that consists of decoupling the delivery of a tumor monoclonal antibody (mAb) from the delivery of the radionuclide. This results in a much higher tumor-to-normal tissue ratio and is favorable for therapy as well and imaging. This includes various strategies based on avidin/streptavidin-biotin, DNA-complementary DNA, and bispecific antibody-hapten bindings. pRIT continuously evolves with the investigation of new molecular constructs and the development of radiochemistry. Pharmacokinetics improve dosimetry depending on the radionuclides used (alpha, beta, and Auger emitters) with prediction of tumor response and host toxicities. New constructs such as the Dock and Lock technology allow production of a variety of mABs directed against tumor-associated antigens. Survival benefit has already been shown in medullary thyroid carcinoma. Improvement in delivery of radioactivity to tumors with these pretargeting procedures associated with reduced hematologic toxicity will become the next generation of RIT. The following review addresses actual technical and clinical considerations and future development of pRIT.

Pretargeted molecular imaging and radioimmunotherapy

Pretargeting is a multi-step process that first has an unlabeled bispecific antibody (bsMAb) localize within a tumor by virtue of its anti-tumor binding site(s) before administering a small, fast-clearing radiolabeled compound that then attaches to the other portion of the bsMAb. The compound's rapid clearance significantly reduces radiation exposure outside of the tumor and its small size permits speedy delivery to the tumor, creating excellent tumor/nontumor ratios in less than 1 hour. Haptens that bind to an anti-hapten antibody, biotin that binds to streptavidin, or an oligonucleotide binding to a complementary oligonucleotide sequence have all been radiolabeled for use by pretargeting. This review will focus on a highly flexible anti-hapten bsMAb platform that has been used to target a variety of radionuclides to image (SPECT and PET) as well as treat tumors.

Cancer radioimmunotherapy

Targeting of radionuclides with antibodies, or radioimmunotherapy, has been an active field of research spanning nearly 50 years, evolving with advancing technologies in molecular biology and chemistry, and with many important preclinical and clinical studies illustrating the benefits, but also the challenges, which all forms of targeted therapies face. There are currently two radiolabeled antibodies approved for the treatment of non-Hodgkin lymphoma, but radioimmunotherapy of solid tumors remains a challenge. Novel antibody constructs, focusing on treatment of localized and minimal disease, and pretargeting are all promising new approaches that are currently under investigation.

Pretargeted radioimmunotherapy (pRAIT) in medullary thyroid cancer (MTC)

Prognosis of medullary thyroid carcinoma (MTC) varies from long- to short-term survival, based on prognostic factors, such as serum calcitonin doubling time (Ct DT). Pretargeted radioimmunotherapy (pRAIT) is a novel targeted radionuclide therapy, using a bispecific monoclonal antibody (BsMAb) and a radiolabeled bivalent hapten, designed to improve the therapeutic index and to deliver increased tumor-absorbed doses to relatively radioresistant solid tumors. Pretargeting has demonstrated a more favorable therapeutic index and clinical efficacy than directly labeled anti-carcinoembryonic antigen (CEA) MAb in preclinical MTC models. Moreover, two phase I/II clinical trials assessing anti-CEA × anti-DTPA-indium BsMAb (murine F6x734 and chimeric hMN14x734) with (131)I-di-DTPA-indium showed encouraging therapeutic results in progressive, metastatic, MTC patients, with an improved survival in intermediate- and high-risk (pre-pRAIT Ct DT, <2 years) patients, as compared to contemporaneous untreated patients (median overall survival, 110 months vs 61 months; P < 0.030). pRAIT efficacy has been recently confirmed in a prospective multicenter phase II study assessing hMN14x734 and (131)I-di-DTPA-indium in rapidly progressive MTC patients. New pRAIT compounds are now available with fully humanized, recombinant, trivalent BsMAb (anti-CEA TF2) and histamine-succinyl-glutamine (HSG) peptides. The HSG peptide allows easy and stable labeling with different radiometals, such as (177)Lu or (90)Y beta-emitters having favorable physical features for pRAIT or (68)Ga and (18)F positron-emitters, allowing the development of a highly sensitive and specific immuno-positron emission tomography method in MTC or other CEA-positive tumors.

¹⁸F-FDG-PET and ¹⁸F-FDG-PET/CT in the detection of recurrent or metastatic medullary thyroid carcinoma: a systematic review and meta-analysis

The aim of this study was to investigate diagnostic performance of (18) F-fluorodeoxyglucose position emission tomography (FDG-PET) and PET/computed tomography (PET/CT) for detection of recurrent or metastatic medullary thyroid carcinoma (MTC) in patients after surgery with a meta-analysis. MEDLINE and EMBASE databases were searched for relevant articles. Two investigators independently extracted the data about study characteristics and examination results. Pooled estimates of sensitivity of FDG-PET or FDG-PET/CT were obtained. Fifteen studies met all inclusion criteria. The sensitivity of FDG-PET ranged from 0.47 (95% confidence intervals (CI): 0.21-0.73) to 0.96 (95%CI: 0.86-0.99), the sensitivity of FDG-PET/CT ranger from 0.47 (95% CI: 0.31-0.64) to 0.80 (95% CI: 0.65-0.90). The pooled sensitivities of FDG-PET and PET/CT were 0.68 (95% CI: 0.64-0.72) and 0.69 (95% CI: 0.64-0.74), respectively. There was no statistic significant between FDG-PET and PET/CT. Our results indicate that FDG-PET or FDG-PET/CT has reasonable sensitivity in detecting recurrent or metastatic MTC after primary surgery. However, no single diagnostic technique is able to reliably demonstrate the full extent of disease in patients with recurrent or metastatic MTC, the combination of cross-sectional radiography with FDG-PET or PET/CT is recommended.

Dosimetry results suggest feasibility of radioimmunotherapy using anti-CD138 (B-B4) antibody in multiple myeloma patients

Syndecan-1 (CD138), a heparan sulfate proteoglycan, is constantly expressed on tumor cells in multiple myeloma (MM). This surface antigen is an attractive candidate for targeted therapy, especially radioimmunotherapy (RAIT). We report preliminary biodistribution and dosimetry results obtained in refractory MM patients in a phase I/II RAIT study using iodine-131-labeled anti-CD138 (B-B4) monoclonal antibody (mAb). Four patients with progressive disease were enrolled after three lines of therapy. They received 370 MBq (20 mg/m(2)) of (131)I-B-B4 for the dosimetry study. Each patient underwent a whole body (WB) CT and four WB emission scans at days D0, D1, and D3-4. Images were corrected for attenuation and scatter to assess doses absorbed by organs and bone marrow (BM). Blood and urine samples were additionally collected. Dosimetry was conducted using the MIRD method. Images obtained 1 h after (131)I-B-B4 injection showed high BM and liver uptake without kidney uptake. The BM uptake confirmed BM involvement as detected by pre-inclusion FDG PET/CT. Absorbed doses were calculated at 2.03 ± 0.3 mGy/MBq for the liver, 1.10 ± 0.9 mGy/MBq for the kidneys, and 0.52 ± 0.20 mGy/MBq for the BM. Grade III thrombocytopenia was documented in two cases (highest BM-absorbed doses), and no grade IV hematological toxicity was observed. Therefore, autologous stem cells were not infused. One patient out of four experienced partial response, with 60% reduction of M-spike on serum electrophoresis, and total relief of pain, lasting for 1 year. This patient was able to go back to work. In this proof of concept study based on dosimetry, we show that MM RAIT is feasible using the anti-CD138 antibody. It would be of great interest to perform a RAIT phase I/II trial with a humanized anti-CD138 mAb with increased doses and systematic autologous stem cell infusions to overcome hematological toxicity and achieve efficacy.

Pretargeted radioimmunotherapy in the treatment of metastatic medullary thyroid cancer

Medullary thyroid carcinoma (mtc) is a rare cancer (less than 8% of all thyroid cancers) that occurs both as a familial and as a sporadic disease [...]

Advances in Radioimmunotherapy in the Age of Molecular Engineering and Pretargeting

Now that radioimmunotherapy is an approved method for the treatment of certain types of non-Hodgkin's lymphoma, investigators are turning to new approaches to further improve radionuclide targeting in hopes of expanding the use of this technology. A number of innovative recombinant proteins have been developed with more favorable pharmacokinetic and targeting properties than standard whole IgG, which conceivably could improve the therapeutic index for cancer treatment. Pretargeting methods also are coming of age, with preclinical and early clinical studies in a variety of cancers illustrating how this alternative approach can enhance the therapeutic window several-fold of what has been possible with directly radiolabeled IgG. This review will discuss some of these promising new developments.

Medullary thyroid cancer: management guidelines of the American Thyroid Association

BACKGROUND

Inherited and sporadic medullary thyroid cancer (MTC) is an uncommon and challenging malignancy. The American Thyroid association (ATA) chose to create specific MTC Clinical Guidelines that would bring together and update the diverse MTC literature and combine it with evidence-based medicine and the knowledge and experience of a panel of expert clinicians.

METHODS

Relevant articles were identified using a systematic PubMed search and supplemented with additional published materials. Evidence-based recommendations were created and then categorized using criteria adapted from the United States Preventive Services Task Force, Agency for Healthcare Research and Quality.

RESULTS

Clinical topics addressed in this scholarly dialog included: initial diagnosis and therapy of preclinical disease (including RET oncogene testing and the timing of prophylactic thyroidectomy), initial diagnosis and therapy of clinically apparent disease (including preoperative testing and imaging, extent of surgery, and handling of devascularized parathyroid glands), initial evaluation and treatment of postoperative patients (including the role of completion thyroidectomy), management of persistent or recurrent MTC (including the role of tumor marker doubling times, and treatment of patients with distant metastases and hormonally active metastases), long-term follow-up and management (including the frequency of follow-up and imaging), and directions for future research.

CONCLUSIONS

One hundred twenty-two evidence-based recommendations were created to assist in the clinical care of MTC patients and to share what we believe is current, rational, and optimal medical practice.

Sensitivity and prognostic value of positron emission tomography with F-18-fluorodeoxyglucose and sensitivity of immunoscintigraphy in patients with medullary thyroid carcinoma treated with anticarcinoembryonic antigen-targeted radioimmunotherapy

CONTEXT

Patients with progressive medullary thyroid carcinoma (MTC) undergo multiple imaging procedures for diagnosis of relapse and staging.

OBJECTIVE

Our objective was to assess the sensitivity and prognostic value of 18F-2-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/computed tomography (CT), and the imaging sensitivity of pretargeted iodine-131-radioimmunotherapy (RIT) in patients with progressive MTC.

DESIGN/SETTING/PATIENTS

We performed a prospective multicenter study in high-risk patients with rapidly progressing MTC enrolled in a phase-II pretargeted RIT study, as documented by short serum calcitonin (Ct) or carcinoembryonic antigen (CEA) doubling time (DT). INTERVENTIONS/MAIN OUTCOME MEASURES: Patients underwent neck-thoracic-abdominal CT, spine and pelvic magnetic resonance imaging, whole-body post-RIT immunoscintigraphy (IS) with iodine-131, and whole-body 18F-FDG-PET/CT imaging. Imaging sensitivity and the correlation between FDG uptake and biomarkers DT were evaluated.

RESULTS

A total of 33 patients with mean CEA and Ct DTs of 1.90 yr (range 0.21-8.50) and 1.52 yr (range 0.09-6.01), respectively, were evaluated. Sensitivity of FDG-PET/CT was 83% for neck, 85% for mediastinal, 75% for lung, 60% for liver, and 67% for bone metastases; overall sensitivity was 76%. Median standardized uptake value (SUVmax) was 5.23 (2.06-13.90). SUVmax correlated significantly with Ct DT (P = 0.011) and minimal DT (minimal value between CEA DT and Ct DT) (P = 0.027). Overall sensitivity of post-RIT IS, CT, and bone magnetic resonance imaging were 94, 74, and 85%, respectively.

CONCLUSIONS

These results demonstrate the value of FDG-PET/CT for staging of patients with progressive MTC, especially in the neck and mediastinum, with possible prognostication by SUV quantification. Post-RIT IS was the most sensitive of the imaging modalities studied prospectively.

Imaging medullary thyroid carcinoma with persistent elevated calcitonin levels

PURPOSE

Because calcitonin level remains elevated after initial treatment in many medullary thyroid carcinoma (MTC) patients without evidence of disease in the usual imaging work-up, there is a need to define optimal imaging procedures.

PATIENTS AND METHODS

Fifty-five consecutive elevated calcitonin level MTC patients were enrolled to undergo neck and abdomen ultrasonography (US); neck, chest, and abdomen spiral computed tomography (CT); liver and whole-body magnetic resonance imaging (MRI); bone scintigraphy; and 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/CT scan (PET).

RESULTS

Fifty patients underwent neck US, CT, and PET, and neck recurrence was demonstrated in 56, 42, and 32%, respectively. Lung and mediastinum lymph node metastases in the 55 patients were demonstrated in 35 and 31% by CT and in 15 and 20% by PET. Liver imaging with MRI, CT, US, and PET in 41 patients showed liver in 49, 44, 41, and 27% patients, respectively. Bone metastases in 55 patients were demonstrated in 35% by PET, 40% by bone scintigraphy, and 40% by MRI; bone scintigraphy was complementary with MRI for axial lesions but superior for the detection of peripheral lesions. Ten patients had no imaged tumor site despite elevated calcitonin level (median 196 pg/ml; range 39-816). FDG uptake in neoplastic foci was higher in progressive patients but with a considerable overlap with stable ones.

CONCLUSION

The most efficient imaging work-up for depicting MTC tumor sites would consist of a neck US, chest CT, liver MRI, bone scintigraphy, and axial skeleton MRI. FDG PET scan appeared to be less sensitive and of low prognostic value.

Medullary thyroid cancer: monitoring and therapy

This article summarizes the clinical features and molecular pathogenesis of medullary thyroid cancer (MTC) and focuses on the current use of molecular, biochemical, and imaging disease markers as a basis for selection of appropriate therapy. Clinicians treating patients who have MTC face the following challenges: (1) distinguishing MTC as early as possible from benign nodular disease and differentiated thyroid cancer to choose the appropriate initial surgery, (2) managing low-level residual cancer in otherwise asymptomatic individuals, and (3) treating progressive metastatic disease. Early clinical trials using small molecules targeting Ret or vascular endothelial growth factor receptors suggest that such approaches could be effective and well tolerated. This article highlights early progress in targeted therapy of MTC and significant challenges in disease monitoring to appropriately select and evaluate patients being treated with these therapies.

Nuclear medicine procedures in the diagnosis and therapy of medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor originating in the parafollicular cells (C cells) of the thyroid and secretes both calcitonin and carcino-embryonic antigen (CEA). Genetic and biochemical testing allow early pre-clinical identification of familial forms. Sporadic MTC usually presents as a solitary thyroid nodule; the diagnosis can be made preoperatively by fine-needle aspiration or by calcitonin assay, though it is usually established at the time of surgery. In the diagnostic assessment of MTC, nuclear medicine imaging provides its contribution mainly in the post-operative work-up to detect residual/recurrent tumor. For such purpose a number of radiopharmaceuticals, which take advantage of the specific expression of receptors (the somatostatin analogue (111)In-octreotide), hormone transporters (radiolabelled MIBG) or molecular targets (radiolabelled anti-CEA monoclonal antibodies) by MTC lesions are available; these tracers may be used also for the palliative treatment of advanced MTC. Interesting perspectives for MTC imaging are offered by PET radiopharmaceuticals.

Medullary Thyroid Carcinoma

Medullary thyroid carcinoma is a neuroendocrine tumor derived from the C cells of the thyroid gland and accounts for approximately 5% of all thyroid carcinomas. Approximately 30% of the cases are associated with an autosomal dominant syndrome called multiple endocrine neoplasia type 2, and the identification of these individuals is important because affected family members may benefit from an early diagnosis. The treatment of this disease is predominantly surgical, and the impact of radiotherapy and chemotherapy is limited. The identification of the associated molecular events has lead to the development of specific molecular targeted agents that may change the way this disease is treated in the near future.

Medullary thyroid cancer: a retrospective analysis of a cohort treated at a single tertiary care center between 1970 and 2005

OBJECTIVE

To identify prognostic factors of clinical outcome and long-term survival in medullary thyroid cancer (MTC).

DESIGN

Retrospective case series of 51 consecutive patients (mean age 46.9 years, 57% female) treated at a single tertiary university medical center from 1970 to 2005. Medical records were reviewed for demographic data, laboratory and clinical course, treatment, and long-term outcome.

MAIN OUTCOME

At presentation, 25 patients (49%) had local disease and 26 (51%) had metastatic disease (three with distant metastases). RET mutations were identified in nine of 23 patients tested. The patients with hereditary disease were younger than the patients with sporadic disease (p < 0.001) and had lower calcitonin levels at diagnosis (p = 0.004) and more multicentric tumors (p = 0.02). Initial surgery consisted of total thyroidectomy in 47 patients, with neck dissection in 26; 22 patients achieved long-term remission. The 5-, 10- and 15-year survival rates were 88%, 85%, and 77%, respectively. On univariate analysis, distant metastases during the course of the disease and elevated calcitonin levels postoperatively were significant prognostic factors of reduced survival (p = 0.001 and 0.016, respectively). Lymph node involvement at initial surgery was associated with a lower remission rate (p = 0.016) but had no impact on long-term survival (p = 0.269).

CONCLUSION

Patients with MTC have a generally favorable outcome, perhaps owing to recent advances in diagnosis and treatment. Although postoperative serum calcitonin level and distant metastases are the only determinants of long-term survival, the presence of cervical metastases is predictive of a higher risk of recurrent or persistent disease.

Cancer Imaging and Therapy with Bispecific Antibody Pretargeting

This article reviews recent preclinical and clinical advances in the use of pretargeting methods for the radioimmunodetection and radioimmunotherapy of cancer. Whereas directly-labeled antibodies, fragments, and subfragments (minibodies and other constructs) have shown promise in both imaging and therapy applications over the past 25 years, their clinical adoption has not fulfilled the original expectations due to either poor image resolution and contrast in scanning or insufficient radiation doses delivered selectively to tumors for therapy. Pretargeting involves the separation of the localization of tumor with an anticancer antibody from the subsequent delivery of the imaging or therapeutic radionuclide. This has shown improvements in both imaging and therapy by overcoming the limitations of conventional, or 1-step, radioimmunodetection or radioimmunotherapy. We focus herein on the use of bispecific antibodies followed by radiolabeled peptide haptens as a new modality of selective delivery of radionuclides for the imaging and therapy of cancer. Our particular emphasis in pretargeting is the use of bispecific trimeric (3 Fab's) recombinant constructs made by a modular method of antibody and protein engineering of fusion molecules called Dock and Lock (DNL).

Experimental immunotherapy of colorectal carcinoma by monoclonal antibody ND4

The potential for experimental immunotherapy of colorectal cancers by mouse IgG2a monoclonal antibody (MAb) ND4 is investigated. The MAb ND4 recognizes a 160 kd cell surface glycoprotein that is strongly expressed in 58% of colorectal carcinomas. The antibody is internalizable by MIP-101 colorectal carcinoma cells. Biodistribution studies in nude mice bearing MIP-101 subcutaneous tumors showed accumulation of 125I-ND4 MAb in tumors from 5% at 18 hours to 14% of the injected dose per gram tissue at 14 days after intraperitoneal (i.p.) injection. Experimental immunotherapy studies using 125I-ND4 in MIP-101 tumor-bearing nude mice showed 64% inhibition of tumor growth 2 weeks after two i.p. injections at 7-day intervals. The MAb ND4 may be useful as a therapeutic reagent for colorectal tumors.

Multimodal imaging analysis of tumor progression and bone resorption in a murine cancer model

OBJECTIVE

This study evaluates the use of multimodal imaging to qualitatively and quantitatively measure tumor progression and bone resorption in a xenotransplanted tumor model of human neuroblastoma.

METHODS

Human neuroblastoma cells expressing a luciferase reporter gene were injected into the femur of nu/nu mice. Tumor progression with and without zoledronic acid treatment was monitored using radiographs, D-luciferin-induced luminescence, micro-computer tomography (CT) and micro-magnetic resonance imaging (MRI).

RESULTS

We observed a gradual increase in D-luciferin-based bioluminescence concomitant with detectable osteolytic lesions. Tumor growth was inhibited (P=0.003-0.07) with zoledronic acid treatment. Micro-CT analysis in vivo provided a method to quantify bone loss, and its prevention by zoledronic acid. High-resolution MRI images allowed the observation of tumor cells within the bone marrow cavity, as well as distant metastasis.

CONCLUSION

Multimodal imaging allows to measure tumor growth and bone resorption simultaneously in vivo and also proved useful in the detection distant metastasis.

Survival improvement in patients with medullary thyroid carcinoma who undergo pretargeted anti-carcinoembryonic-antigen radioimmunotherapy: a collaborative study with the French Endocrine Tumor Group

PURPOSE

No effective therapy is currently available for the management of patients with metastatic medullary thyroid carcinoma (MTC). The efficacy of pretargeted radioimmunotherapy (pRAIT) with bispecific monoclonal antibody (BsMAb) and a iodine-131 (131I) -labeled bivalent hapten is evaluated.

PATIENTS AND METHODS

Twenty-nine patients with advanced, progressive MTC, as documented by short serum calcitonin doubling times (Ct DTs), received an anti-carcinoembryonic antigen (CEA)/anti-diethylenetriamine pentaacetic acid (DTPA) -indium BsMAb, followed 4 days later by a 131I-labeled bivalent hapten. Overall survival (OS) was compared with 39 contemporaneous untreated MTC patients with comparable prognostic indicators.

RESULTS

OS was significantly longer in high-risk, treated patients (Ct DT < 2 years) than in high-risk, untreated patients (median OS, 110 v 61 months; P < .030). Forty-seven percent of patients, defined as biologic responders by a more than 100% increase in CtDT, experienced significantly longer survival than nonresponders (median OS, 159 v 109 months; P < .035) and untreated patients (median OS, 159 v 61 months; P < .010). Treated patients with bone/bone-marrow disease had a longer survival than patients without such involvement (10-year OS, 83% v 14%; P < .023). Toxicity was mainly hematologic and related to bone/bone-marrow tumor spread.

CONCLUSION

pRAIT against CEA induced long-term disease stabilization and a significantly longer survival in high-risk patients with Ct DTs less than 2 years, compared with similarly high-risk, untreated patients. Ct DT and bone-marrow involvement appear to be prognostic indicators in MTC patients who undergo pRAIT.

Improving the delivery of radionuclides for imaging and therapy of cancer using pretargeting methods

The article reviews the background and current status of pretargeting for cancer imaging and therapy with radionuclides. Pretargeting procedures were introduced approximately 20 years ago as an alternative to directly radiolabeled antibodies. Because they were multistep processes, they were met with resistance but have since progressed to simple and improved procedures that could become the next generation of imaging and therapy with radionuclides. The separation of the radiolabeled compound from the antibody-targeting agent affords pretargeting procedures considerable flexibility in the radiolabeling process, providing opportunities for molecular imaging using gamma- or positron-emitting radionuclides and a variety of beta- and alpha-emitting radionuclides of therapeutic applications. Pretargeting methods improve tumor/nontumor ratios, exceeding that achieved with directly radiolabeled Fab' fragments, particularly within just a few hours of the radionuclide injection. In addition, tumor uptake exceeds that of a Fab' fragment by as much as 10-fold, giving pretargeting a greatly enhanced sensitivity for imaging. Advances in molecular biology have led to the development of novel binding proteins that have further improved radionuclide delivery in these systems. Studies in a variety of hematologic and solid tumor models have shown advantages of pretargeting compared with directly radiolabeled IgG for therapy, and there are several clinical studies under way that are also showing promising results. Thus, the next generation of targeting agents will likely employ pretargeting approaches to optimize radionuclide delivery for a wide range of applications.

Antibody pretargeting advances cancer radioimmunodetection and radioimmunotherapy

This article reviews the methods of pretargeting, which involve separating the targeting antibody from the subsequent delivery of an imaging or therapeutic agent that binds to the tumor-localized antibody. This provides enhanced tumor:background ratios and the delivery of a higher therapeutic dose than when antibodies are directly conjugated with radionuclides, as currently practiced in cancer radioimmunotherapy. We describe initial promising clinical results using streptavidin-antibody constructs with biotin-radionuclide conjugates in the treatment of patients with malignant gliomas, and of bispecific antibodies with hapten-radionuclides in the therapy of tumors expressing carcinoembryonic antigen, such as medullary thyroid and small-cell lung cancers.

Selective arterial chemoembolization for hepatic metastases from medullary thyroid carcinoma

BACKGROUND

Hepatic metastases from medullary thyroid carcinoma (MTC) may impair quality of life by hypercalcitonemia-associated diarrhea and pain. In this prospective study, the effect of selective arterial chemoembolization (SACE) was evaluated.

METHODS

Eleven patients with hepatic metastases from MTC received 1 to 9 courses of SACE using epirubicine. Symptomatic, biochemical, and morphologic responses on SACE were recorded.

RESULTS

Symptomatic response was observed in all symptomatic patients. However, biochemical and radiologic response occurred only in 6 patients. Liver function was not affected by SACE. One patient with unexpected concurrent pheochromocytoma metastases died after the first course. Development of side effects in the course was observed in 8 patients but were only World Health Organization grade 1. Patients' satisfaction with SACE was excellent. Long-term follow-up found 7 patients alive (1-72 months). Three patients died with tumor 6, 12, and 24 months after SACE, respectively.

CONCLUSION

SACE provided good symptom palliation for the majority of patients with hepatic metastases from MTC. However, transient remission or stabilization of hepatic metastases resulted in only 60%. Further studies using a randomized protocol are required.

Repeated [131I]metaiodobenzylguanidine therapy in two patients with malignant pheochromocytoma

CONTEXT

Approximately 10% of pheochromocytomas are malignant with a 5-yr survival rate of less than 40%. Promising results have been published on single high-dosage [131I]metaiodobenzylguanidine ([131I]MIBG) treatment for malignant pheochromocytoma. We present our experience with multiple intermediate-dosage [131I]MIBG therapy instead of single high-dosage therapy.

SETTING AND PATIENTS

The study took place at University Medical Centers and included two patients (one male, 36 yr of age, and one female, 43 yr of age) with widely spread metastatic pheochromocytoma and bad prognosis because of liver and lung metastases.

INTERVENTIONS

Instead of a single high dosage, these two patients were treated with multiple intermediate dosages of [131I]MIBG. The first patient received 37 GBq (1 Ci) [131I]MIBG in five sessions [7400 MBq (200 mCi) each; interval range, 2-11 months]; the second patient received 66.6 GBq (1.8 Ci) [131I]MIBG in 12 sessions [5550 MBq (150 mCi) each; interval range, 2-14 months].

OUTCOME MEASURES

We measured efficacy, toxicity, and survival.

RESULTS

Both patients had a complete symptomatic response and a partial tumor volume response. The first patient had a partial biochemical response, the second a complete biochemical response. In both cases, toxicity has been confined to nausea during treatment. Hematological toxicity was minimal, and both patients stayed euthyroid. The survival (so far) of these patients was 5 yr (clinical case 1) and 16 yr (clinical case 2) after initial diagnosis.

CONCLUSIONS

Repeated intermediate-dosage [131I]MIBG treatment appears to be a reliable and well-tolerated radionuclide therapy and might be a useful adjunct in patients with malignant pheochromocytoma, providing longstanding palliation and prolonged survival.