title: From preclinical development to clinical application: Kit formulation for radiolabelling the minigastrin analogue CP04 with In-111 for a first-in-human clinical trial.
abstract: BACKGROUND
  A variety of radiolabelled minigastrin analogues targeting the cholecystokinin 2 (CCK2) receptor were developed and compared in a concerted preclinical testing to select the most promising radiotracer for diagnosis and treatment of medullary thyroid carcinoma (MTC). DOTA-DGlu-DGlu-DGlu-DGlu-DGlu-DGlu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2 (CP04) after labelling with (111)In displayed excellent characteristics, such as high stability, receptor affinity, specific and persistent tumour uptake and low kidney retention in animal models. Therefore, it was selected for further clinical evaluation within the ERA-NET project GRAN-T-MTC. Here we report on the development of a pharmaceutical freeze-dried formulation of the precursor CP04 for a first multi-centre clinical trial with (111)In-CP04 in MTC patients.
  
  
  METHODS
  The kit formulation was optimised by adjustment of buffer, additives and radiolabelling conditions. Three clinical grade batches of a final kit formulation with two different amounts of peptide (10 or 50 μg) were prepared and radiolabelled with (111)In. Quality control and stability assays of both the kits and the resulting radiolabelled compound were performed by HPLC analysis.
  
  
  RESULTS
  Use of ascorbic acid buffer (pH4.5) allowed freeze-drying of the kit formulation with satisfactory pellet-formation. Addition of methionine and gentisic acid as well as careful selection of radiolabelling temperature was required to avoid extensive oxidation of the Met(11)-residue. Trace metal contamination, in particular Zn, was found to be a major challenge during the pharmaceutical filling process in particular for the 10 μg formulation. The final formulations contained 10 or 50 μg CP04, 25mg ascorbic acid, 0.5mg gentisic acid and 5mg L-methionine. The radiolabelling performed by incubation of 200-250 MBq (111)InCl3 at 90 °C for 15 min resulted in reproducible radiochemical purity (RCP) >94%. Kit-stability was proven for >6 months at +5 °C and at +25 °C. The radiolabelled product was stable for >4h at +25 °C.
  
  
  CONCLUSIONS
  A kit formulation to prepare (111)In-CP04 for clinical application was developed, showing high stability of the kit as well as high RCP of the final product.
authors.affiliation: Radioisotope Centre POLATOM, National Centre for Nuclear Research, Otwock, Poland.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Pawlak
authors.affiliation: Dept. of Nuclear Medicine, Medical University Innsbruck, Austria.
authors.forename: Christine
authors.initials: C
authors.lastname: Rangger
authors.affiliation: Dept. of Nuclear Medicine, University Medical Centre Ljubljana, Slovenia.
authors.forename: Petra
authors.initials: P
authors.lastname: Kolenc Peitl
authors.affiliation: Radioisotope Centre POLATOM, National Centre for Nuclear Research, Otwock, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Garnuszek
authors.affiliation: Radioisotope Centre POLATOM, National Centre for Nuclear Research, Otwock, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Maurin
authors.affiliation: Dept. of Nuclear Medicine, Medical University Innsbruck, Austria.
authors.forename: Laura
authors.initials: L
authors.lastname: Ihli
authors.affiliation: Dept. of Nuclear Medicine, University Medical Centre Ljubljana, Slovenia.
authors.forename: Marko
authors.initials: M
authors.lastname: Kroselj
authors.affiliation: Molecular Radiopharmacy, INRASTES, NCSR "Demokritos", Athens, Greece.
authors.forename: Theodosia
authors.initials: T
authors.lastname: Maina
authors.affiliation: Dept. of Nuclear Medicine, University Hospital Freiburg, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Maecke
authors.affiliation: Dept. of Nuclear Medicine, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Erba
authors.affiliation: Division of Clinical Biochemistry, Biocenter, Medical University Innsbruck, Austria.
authors.forename: Leopold
authors.initials: L
authors.lastname: Kremser
authors.affiliation: Dept. 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: Mikołajczak
authors.affiliation: Dept. of Nuclear Medicine, Medical University Innsbruck, Austria. Electronic address: Clemens.Decristoforo@i-med.ac.at.
authors.forename: Clemens
authors.initials: C
authors.lastname: Decristoforo
mesh_terms: D018278:Carcinoma, Neuroendocrine / Q000188:drug therapy; D002626:Chemistry, Pharmaceutical / Q000379:methods; D002986:Clinical Trials as Topic; D004355:Drug Stability; D005612:Freeze Drying / Q000379:methods; D005755:Gastrins / Q000737:chemistry* / Q000627:therapeutic use; D006801:Humans; D007205:Indium Radioisotopes / Q000737:chemistry*; D008715:Methionine / Q000737:chemistry; D015337:Multicenter Studies as Topic; D010455:Peptides / Q000737:chemistry; D011868:Radioisotopes / Q000737:chemistry*; D019275:Radiopharmaceuticals / Q000737:chemistry*; D013964:Thyroid Neoplasms / Q000188:drug therapy
chemical_list: D005755:Gastrins; D007205:Indium Radioisotopes; D010455:Peptides; D011868:Radioisotopes; D019275:Radiopharmaceuticals; C008530:minigastrin; D008715:Methionine
keywords: Ascorbic acid (PubChem CID: 54670067); Formulation; Freeze-Drying; Gentisic acid (PubChem CID: 3469); In-111; Medullary thyroid carcinoma; Minigastrin; Radiopharmaceutical Kit; Sodium hydroxide (PubChem CID: 14798); l-Methionine (PubChem CID: 6137)
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