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      Preclinical pharmacokinetics, biodistribution, radiation dosimetry and toxicity studies required for regulatory approval of a phase I clinical trial with 111In-CP04 in medullary thyroid carcinoma patients

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          Abstract

          Introduction

          From a series of radiolabelled cholecystokinin (CCK) and gastrin analogues, 111In-CP04 ( 111In-DOTA-(DGlu) 6-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH 2) was selected for further translation as a diagnostic radiopharmaceutical towards a first-in-man study in patients with medullary thyroid carcinoma (MTC). A freeze-dried kit formulation for multicentre application has been developed. We herein report on biosafety, in vivo stability, biodistribution and dosimetry aspects of 111In-CP04 in animal models, essential for the regulatory approval of the clinical trial.

          Materials and methods

          Acute and extended single dose toxicity of CP04 was tested in rodents, while the in vivo stability of 111In-CP04 was assessed by HPLC analysis of mouse blood samples. The biodistribution of 111In-CP04 prepared from a freeze-dried kit was studied in SCID mice bearing double A431-CCK2R(±) xenografts at 1, 4 and 24 h pi. Further 4-h animal groups were either additionally treated with the plasma expander gelofusine or injected with 111In-CP04 prepared by wet-labelling. Pharmacokinetics in healthy mice included the 30 min, 1, 4, 24, 48 and 72 h time points pi. Dosimetric calculations were based on extrapolation of mice data to humans adopting two scaling models.

          Results

          CP04 was well-tolerated by both mice and rats, with an LD 50 > 178.5 μg/kg body weight for mice and a NOAEL (no-observed-adverse-effect-level) of 89 μg/kg body weight for rats. After labelling, 111In-CP04 remained >70% intact in peripheral mouse blood at 5 min pi. The uptake of 111In-CP04 prepared from the freeze-dried kit and by wet-labelling were comparable in the A431-CCK2R(+)-xenografts (9.24 ± 1.35%ID/g and 8.49 ± 0.39%ID/g, respectively; P > 0.05). Gelofusine-treated mice exhibited significantly reduced kidneys values (1.69 ± 0.15%ID/g vs. 5.55 ± 0.94%ID/g in controls, P < 0.001). Dosimetry data revealed very comparable effective tumour doses for the two scaling models applied, of 0.045 and 0.044 mSv/MBq.

          Conclusion

          The present study has provided convincing toxicology, biodistribution and dosimetry data for prompt implementation of the freeze-dried kit formulation without or with gelofusine administration in a multicentre clinical trial in MTC patients.

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          Most cited references 29

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          Molecular genetics of thyroid cancer: implications for diagnosis, treatment and prognosis.

          Thyroid cancer is the most common malignant tumor of the endocrine system and accounts for approximately 1% of all newly diagnosed cancer cases. The most frequent type of thyroid malignancy is papillary carcinoma, which constitutes approximately 80% of all cases. Papillary carcinomas frequently have genetic alterations leading to the activation of the MAPK signal pathway. Those include RET/PTC rearrangement and point mutations of the BRAF and RAS genes. Mutations in these genes are found in over 70% of papillary carcinomas and they rarely overlap in the same tumor. Frequent genetic alterations in follicular carcinomas, the second most common type of thyroid malignancy, include RAS mutations and PAX8-PPAR gamma rearrangement. RET point mutations are crucial for the development of medullary thyroid carcinomas. Many of these mutations, particularly those leading to the activation of the MAPK pathway, are being actively explored as therapeutic targets for thyroid cancer. Detection of these genetic alterations using molecular techniques is important for preoperative fine-needle aspiration diagnosis, prognosis and treatment of thyroid cancer.
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            Medullary thyroid carcinoma.

            Medullary thyroid carcinoma (MTC) accounts for 5-8% of all thyroid cancers. MTC is mainly sporadic in nature, but an hereditary pattern [multiple endocrine neoplasia type 2 (MEN 2)] is present in 20-30% of cases, transmitted as an autosomal-dominant trait due to germline mutations of the RET proto-oncogene. About 98% of patients with MEN 2 have germline mutations in exons 5, 8, 10, 11, 13, 14, 15 or 16 of the RET gene. The primary treatment of both hereditary and sporadic forms of MTC is total thyroidectomy and removal of all neoplastic tissue present in the neck. The therapeutic option for lymph node surgery should be dictated by the results of presurgical evaluation. After total thyroidectomy, measurements of serum calcitonin (CT) and carcinoembryonic antigen are of paramount importance in the postsurgical follow-up of patients with MTC as they reflect the presence of persistent or recurrent disease. Complete remission is demonstrated by undetectable and stimulated serum CT measurement. On the contrary, if serum CT is detectable under basal conditions or becomes detectable after stimulation, the patient is probably not cured, but imaging techniques will not demonstrate any disease until serum CT approaches levels >150 pg/ml. The tumour metastasises early to both paratracheal and lateral cervical lymph nodes. Metastases outside the neck may occur in the liver, lungs, bones and, less frequently, brain and skin. Surgery is the main treatment for local and distant metastases whenever feasible. Systemic chemotherapy with dacarbazine, 5-fluorouracil and doxorubicin (alone or in combination) has shown very limited efficacy, achieving only partial responses in the range of 10-20% and of short duration. Several kinase inhibitors are currently under evaluation and preliminary results are promising. Familial cases must be identified by searching for RET proto-oncogene mutations in the proband and in family members. Carriers of the RET gene are candidates for prophylactic thyroidectomy at different ages depending on the risk associated with the specific RET mutations. Copyright (c) 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
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              Peptide-based probes for cancer imaging.

              Receptors for regulatory peptides are overexpressed in a variety of human cancers. They represent the molecular basis for in vivo imaging with radiolabeled peptide probes. Somatostatin-derived tracers, designed to image the sst2-overexpressing neuroendocrine tumors, have enjoyed almost 2 decades of successful development and extensive clinical applications. More recent developments include second- and third-generation somatostatin analogs, with a broader receptor subtype profile or with antagonistic properties. Emerging tracers for other peptide receptors, including cholecystokinin/gastrin and GLP-1 analogs for neuroendocrine tumors, bombesin and neuropeptide-Y analogs for prostate or breast cancers, or Arg-Gly-Asp peptides for neoangiogenesis labeling, are also in current development. Application fields include both SPECT/CT and PET/CT.
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                Author and article information

                Journal
                9317982
                21091
                Eur J Pharm Sci
                Eur J Pharm Sci
                European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences
                0928-0987
                1879-0720
                12 July 2016
                14 May 2016
                25 August 2016
                25 August 2016
                : 91
                : 236-242
                Affiliations
                [a ]Molecular Radiopharmacy, INRASTES, NCSR “Demokritos”, Athens, Greece
                [b ]Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
                [c ]Department of Nuclear Medicine, University Medical Centre Ljubljana, Slovenia
                [d ]Radioisotope Centre POLATOM, National Centre for Nuclear Research, Otwock, Poland
                [e ]Department of Nuclear Medicine, University Hospital Freiburg, Germany
                [f ]Department of Nuclear Medicine, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy
                [g ]Department of Nuclear Medicine, Innsbruck Medical University, Austria
                [h ]Department of Endocrinology, Jagiellonian University Medical College, Krakow, Poland
                Author notes
                [* ]Corresponding author at: Department of Nuclear Medicine, Innsbruck Medical University, Austria. clemens.decristoforo@ 123456i-med.ac.at (C. Decristoforo).
                Article
                EMS69167
                10.1016/j.ejps.2016.05.011
                4948680
                27185299

                This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/).

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