In this paper, the authors' review the applicability of the open-source GATE Monte Carlo simulation platform based on the GEANT4 toolkit for radiation therapy and dosimetry applications. The many applications of GATE for state-of-the-art radiotherapy simulations are described including external beam radiotherapy, brachytherapy, intraoperative radiotherapy, hadrontherapy, molecular radiotherapy, and in vivo dose monitoring. Investigations that have been performed using GEANT4 only are also mentioned to illustrate the potential of GATE. The very practical feature of GATE making it easy to model both a treatment and an imaging acquisition within the same framework is emphasized. The computational times associated with several applications are provided to illustrate the practical feasibility of the simulations using current computing facilities.

Demobesin 1 is a potent new GRP-R-selective bombesin (BN) analogue containing an open chain tetraamine chelator for stable technetium-99m binding. Following a convenient labelling protocol, the radiopeptide, [(99m)Tc]Demobesin 1, formed in nearly quantitative yields and with high specific activities. Both unlabelled and labelled peptide demonstrated high-affinity binding in membrane preparations of the human androgen-independent prostate adenocarcinoma PC-3 cell line. The IC(50) values determined for Demobesin 1 and [Tyr(4)]BN were 0.70+/-0.08 n M and 1.5+/-0.20 n M, respectively, while the K(d) defined for [(99m)Tc/(99g)Tc]Demobesin 1 was 0.67+/-0.10 n M. [(99m)Tc]Demobesin 1 was rather stable in murine plasma, whereas it degraded rapidly in kidney and liver homogenates. After injection in healthy Swiss albino mice, [(99m)Tc]Demobesin 1 accumulated very efficiently in the target organs (pancreas, intestinal tract) via a GRP-R-mediated process, as shown by in vivo receptor blocking experiments. An equally high and GRP-R-mediated uptake was exhibited by [(99m)Tc]Demobesin 1 after injection in PC-3 tumour-bearing athymic mice. The initial high radioligand uptake of 16.2+/-3.1%ID/g in the PC-3 xenografts at 1 h p.i. remained at a similar level (15.61+/-1.19%ID/g) at 4 h p.i. Even after 24 h p.i., when the radioactivity had cleared from all other tissues, a value of 5.24+/-0.67%ID/g was still observed in the tumour. The high and prolonged localization of [(99m)Tc]Demobesin 1 at the tumour site and its rapid background clearance are very promising qualities for GRP-R-targeted tumour imaging in man.

The use of small animal models in basic and preclinical sciences constitutes an integral part of testing new pharmaceutical agents prior to commercial translation to clinical practice. Whole-body small animal imaging is a particularly elegant and cost-effective experimental platform for the timely validation and commercialization of novel agents from the bench to the bedside. Biomedical imaging is now listed along with genomics, proteomics, and metabolomics as an integral part of biological and medical sciences. Miniaturized versions of clinical diagnostic modalities, including but not limited to microcomputed tomography, micromagnetic resonance tomography, microsinglephoton-emission tomography, micropositron-emission tomography, optical imaging, digital angiography, and ultrasound, have all greatly improved our investigative abilities to longitudinally study various experimental models of human disease in mice and rodents. After an exhaustive literature search, the authors present a concise and critical review of in vivo small animal imaging, focusing on currently available modalities as well as emerging imaging technologies on one side and molecularly targeted contrast agents on the other. Aforementioned scientific topics are analyzed in the context of cancer angiogenesis and innovative antiangiogenic strategies under-the-way to the clinic. Proposed hybrid approaches for diagnosis and targeted site-specific therapy are highlighted to offer an intriguing glimpse of the future.

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Aim: Targeted biocompatible nanoplatforms presenting multiple therapeutic functions have great potential for the treatment of cancer. Materials & methods: Multifunctional nanocomposites formed by polymeric nanoparticles (PNPs) containing two cytotoxic agents -the drug alisertib and silver nanoparticles -were synthesized. These PNPs have been conjugated with a chlorotoxin, an active targeting 36-amino acid-long peptide that specifically binds to MMP-2, a receptor overexpressed by brain cancer cells. Results:The individual and synergistic activity of these two cytotoxic agents against glioblastoma multiforme was tested both in vitro and in vivo. The induced cytotoxicity in a human glioblastoma-astrocytoma epithelial-like cell line (U87MG) was studied in vitro through a trypan blue exclusion test after 48 and 72 h of exposure. Subsequently, the PNPs' biodistribution in healthy animals and their effect on tumor reduction in tumor-bearing mice were studied using PNPs radiolabeled with 99m Tc. Conclusion: Tumor reduction was achieved in vivo when using silver/alisertib@PNPs-chlorotoxin.