Prostate cancer is one of the most common causes of cancer in men. Evaluating the different stages of prostate cancer with conventional imaging techniques still proves difficult. Nuclear imaging might provide a technique that is able to evaluate prostate cancer, but clinical application has been limited due to lack of accuracy of current radiopharmaceuticals. The development of radiopharmaceuticals that can be targeted to specific antigens, overexpressed in prostate cancer, but sparse in normal tissue, is crucial. Peptides are of particular interest because of their favourable characteristics, leading to increased attention for nuclear imaging of the gastrin-releasing-peptide-receptor (GRPR) with radiolabelled bombesin-like peptides. Several derivatives of bombesin and its truncated form have been prepared for imaging with single photon emission computed tomography (SPECT) or positron emission tomography (PET), thereby delivering potent candidates for further clinical evaluation. This article provides an overview of the development and preclinical evaluation of radiolabelled bombesin analogues for in vivo targeting of GRPR in prostate cancer. The effect of the radionuclide, chelator, spacer and unnatural amino acids on affinity, metabolic stability and image quality are discussed, as well as agonistic or antagonistic properties. Potent candidates are proposed based on these selection criteria: (I) high affinity for GRPR, with rapid and specific tumour uptake (II) high hydrophilicity resulting in the preferred renal-urinary mode of excretion and low hepatobiliary excretion, (III) high stability, but relatively rapid clearance from blood. Also, a summary is made of clinical studies that report on the detection of prostate cancer with GRPR targeted radiopharmaceuticals.
Two groups of patients, those treated for Hodgkin's disease and breast cancer, are particularly at risk of developing late myocardial damage, since radiotherapy (RT) techniques for both patient groups may include (large) parts of the heart, and adjuvant systemic therapy is frequently administered to these patients, in particular anthracycline-containing chemotherapy. Available literature on the monitoring and prediction of RT-induced and anthracycline-associated cardiac damage using nuclear medicine techniques is presented. Based on relevant studies, the risk of overall cardiac disease post-RT and overt congestive heart failure during anthracycline-containing chemotherapy is probably low. Conventional nuclear medicine imaging, i.e. myocardial perfusion scintigraphy, may be of complementary use to echocardiographical evaluation for routine follow-up after RT with modern techniques, in a subgroup of patients with known cardiovascular risk factors. Left ventricle ejection fraction (LVEF) measurements, as assessed by radionuclide angiography for the monitoring of anthracycline-associated cardiac injury, are not very sensitive and early detection will probably be enhanced by combining LVEF measurements with other cardiac function parameters. Also, it may be expected that nuclear medicine techniques using molecular radioligands will constitute an essential future step in the evaluation of subclinical cardiac injury afforded by the combined effect of RT and cardiotoxic chemotherapy.
195mPt-cisplatin proved a safe radiopharmaceutical with a favourable biodistribution for early and delayed imaging of pathology above the diaphragm. The ED obtained was 0.185 ± 0.034 mSv/MBq. The highest organ dose was received by the kidneys (2.68 ± 1.5 mGy/MBq).
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