title: Preclinical pharmacokinetics, biodistribution, radiation dosimetry and toxicity studies required for regulatory approval of a phase I clinical trial with (111)In-CP04 in medullary thyroid carcinoma patients.
abstract: BACKGROUND
  From a series of radiolabelled cholecystokinin (CCK) and gastrin analogues, (111)In-CP04 ((111)In-DOTA-(DGlu)6-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2) 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 (111)In-CP04 in animal models, essential for the regulatory approval of the clinical trial.
  
  
  METHODS
  Acute and extended single dose toxicity of CP04 was tested in rodents, while the in vivo stability of (111)In-CP04 was assessed by HPLC analysis of mouse blood samples. The biodistribution of (111)In-CP04 prepared from a freeze-dried kit was studied in SCID mice bearing double A431-CCK2R(±) xenografts at 1, 4 and 24h pi. Further 4-h animal groups were either additionally treated with the plasma expander gelofusine or injected with (111)In-CP04 prepared by wet-labelling. Pharmacokinetics in healthy mice included the 30min, 1, 4, 24, 48 and 72h 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 LD50>178.5μg/kg body weight for mice and a NOAEL (no-observed-adverse-effect-level) of 89μg/kg body weight for rats. After labelling, (111)In-CP04 remained >70% intact in peripheral mouse blood at 5min pi. The uptake of (111)In-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 0.044mSv/MBq.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece.
authors.forename: Theodosia
authors.initials: T
authors.lastname: Maina
authors.affiliation: Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Konijnenberg
authors.affiliation: Department of Nuclear Medicine, University Medical Centre Ljubljana, Slovenia.
authors.forename: Petra
authors.initials: P
authors.lastname: KolencPeitl
authors.affiliation: Radioisotope Centre POLATOM, National Centre for Nuclear Research, Otwock, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Garnuszek
authors.affiliation: Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece.
authors.forename: Berthold A
authors.initials: BA
authors.lastname: Nock
authors.affiliation: Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece.
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Kaloudi
authors.affiliation: Department of Nuclear Medicine, University Medical Centre Ljubljana, Slovenia.
authors.forename: Marko
authors.initials: M
authors.lastname: Kroselj
authors.affiliation: Department of Nuclear Medicine, University Medical Centre Ljubljana, Slovenia.
authors.forename: Katja
authors.initials: K
authors.lastname: Zaletel
authors.affiliation: Department of Nuclear Medicine, University Hospital Freiburg, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Maecke
authors.affiliation: Department of Nuclear Medicine, University Hospital Freiburg, Germany.
authors.forename: Rosalba
authors.initials: R
authors.lastname: Mansi
authors.affiliation: Department of Nuclear Medicine, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Erba
authors.affiliation: Department of Nuclear Medicine, Innsbruck Medical University, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: von Guggenberg
authors.affiliation: Department of Endocrinology, Jagiellonian University Medical College, Krakow, Poland.
authors.forename: Alicja
authors.initials: A
authors.lastname: Hubalewska-Dydejczyk
authors.affiliation: Radioisotope Centre POLATOM, National Centre for Nuclear Research, Otwock, Poland.
authors.forename: Renata
authors.initials: R
authors.lastname: Mikolajczak
authors.affiliation: Department of Nuclear Medicine, Innsbruck Medical University, Austria. Electronic address: clemens.decristoforo@i-med.ac.at.
authors.forename: Clemens
authors.initials: C
authors.lastname: Decristoforo
mesh_terms: D000818:Animals; D018278:Carcinoma, Neuroendocrine / Q000378:metabolism; D017321:Clinical Trials, Phase I as Topic; D004353:Drug Evaluation, Preclinical; D005260:Female; D005755:Gastrins / Q000493:pharmacokinetics* / Q000633:toxicity; D006801:Humans; D007205:Indium Radioisotopes; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D019055:No-Observed-Adverse-Effect Level; D011829:Radiation Dosage; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics* / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar; D013964:Thyroid Neoplasms / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D005755:Gastrins; D007205:Indium Radioisotopes; D019275:Radiopharmaceuticals
keywords: CCK2R-targeting of tumours; Clinical translation; Gastrin-radioligand; Medullary thyroid cancer; Radionuclide therapy; Radiopharmaceutical development