• Biodistribution, pharmacokinetics and metabolism of interleukin-1 receptor antagonist (IL-1RA) using [¹⁸F]-IL1RA and PET imaging in rats.

      Cawthorne, Christopher; Prenant, C; Smigova, A; Julyan, Peter J; Maroy, R; Herholz, K; Rothwell, N; Boutin, H; Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK. (2011-02)
      Positron emission tomography (PET) has the potential to improve our understanding of the preclinical pharmacokinetics and metabolism of therapeutic agents, and is easily translated to clinical studies in humans. However, studies involving proteins radiolabelled with clinically relevant PET isotopes are currently limited. Here we illustrate the potential of PET imaging in a preclinical study of the biodistribution and metabolism of ¹⁸F-labelled IL-1 receptor antagonist ([¹⁸F]IL-1RA) using a novel [¹⁸F]-radiolabelling technique.
    • The hypoxia-selective cytotoxin NLCQ-1 (NSC 709257) controls metastatic disease when used as an adjuvant to radiotherapy.

      Lunt, S; Cawthorne, Christopher; Ali, M; Telfer, B; Babur, M; Smigova, A; Julyan, Peter J; Price, Patricia M; Stratford, I; Bloomer, W; et al. (2010-07-13)
      BACKGROUND: Metastases cause most cancer-related deaths. We investigated the use of hypoxia-selective cytotoxins as adjuvants to radiotherapy in the control of metastatic tumour growth. METHODS: The NLCQ-1, RB6145 and tirapazamine were assessed against the spontaneously metastasising KHT model. Subcutaneous KHT tumours (250 mm(3)) were irradiated with 25 Gy (single fraction) to control primary growth. Equitoxic drug treatments (NLCQ-1 (10 mg kg(-1)) once daily; RB6145 (75 mg kg(-1)) and tirapazamine (13 mg kg(-1)) twice daily) were administered 3-6 days post-radiotherapy when hypoxic cells were evident in lung micrometastases. Mice were culled when 50% of controls exhibited detrimental signs of lung metastases. RESULTS: In total, 95% of control mice presented with lung disease. This was significantly reduced by NLCQ-1 (33%; P=0.0002) and RB6145 (60%; P=0.02). Semi-quantitative grading of lung disease revealed a significant improvement with all treatments, with NLCQ-1 proving most efficacious (median grades: control, 4; NLCQ, 0 (P<0.0001); RB6145, 1 (P<0.001), tirapazamine, 3 (P=0.007)). Positron emission tomography (PET) was evaluated as a non-invasive means of assessing metastatic development. Primary and metastatic KHT tumours showed robust uptake of [(18)F]fluorodeoxyglucose ([(18)F]FDG). Metastatic burden discernable by [(18)F]FDG PET correlated well with macroscopic and histological lung analysis. CONCLUSION: The hypoxia-selective cytotoxin NLCQ-1 controls metastatic disease and may be a successful adjuvant to radiotherapy in the clinical setting.
    • Radiolabeling with fluorine-18 of a protein, interleukin-1 receptor antagonist.

      Prenant, C; Cawthorne, Christopher; Fairclough, M; Rothwell, N; Boutin, H; Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK. cprenant@cyclopharma.fr (2010-09)
      IL-1RA is a naturally occurring antagonist of the pro-inflammatory cytokine interleukin-1 (IL-1) with high therapeutic promise, but its pharmacokinetic remains poorly documented. In this report, we describe the radiolabeling of recombinant human interleukin-1 receptor antagonist (rhIL-1RA) with fluorine-18 to allow pharmacokinetic studies by positron emission tomography (PET). rhIL-1RA was labeled randomly by reductive alkylation of free amino groups (the epsilon-amino group of lysine residues or amino-terminal residues) using [(18)F]fluoroacetaldehyde under mild reaction conditions. Radiosyntheses used a remotely controlled experimental rig within 100min and the radiochemical yield was in the range 7.1-24.2% (decay corrected, based on seventeen syntheses). We showed that the produced [(18)F]fluoroethyl-rhIL-1ra retained binding specificity by conducting an assay on rat brain sections, allowing its pharmakokinetic study using PET.