Tc-99m-NTP 15-5 assessment of the early therapeutic response of chondrosarcoma to zoledronic acid in the Swarm rat orthotopic model

Background: Since proteoglycans (PGs) appear as key partners in chondrosarcoma biology, PG-targeted imaging using the radiotracer 99mTc-N-(triethylammonium)-3-propyl-[15]ane-N5 (99mTc-NTP 15-5) developed by our group was previously demonstrated to be a good single-photon emission computed tomography tracer for cartilage neoplasms. We therefore initiated this new preclinical study to evaluate the relevance of 99mTc-NTP 15-5 imaging for the in vivo monitoring and quantitative assessment of chondrosarcoma response to zoledronic acid (ZOL) in the Swarm rat orthotopic model. Findings: Rats bearing chondrosarcoma in the orthotopic paratibial location were treated by ZOL (100 μg/kg, subcutaneously) or phosphate-buffered saline, twice a week, from day 4 to day 48 post-tumor implantation. 99mTc-NTP 15-5 imaging was performed at regular intervals with the target-to-background ratio (TBR) determined. Tumor volume was monitored using a calliper, and histology was performed at the end of the study. From day 11 to day 48, mean TBR values ranged from 1.7 ± 0.6 to 2.3 ± 0.6 in ZOL-treated rats and from 2.1 ± 1.0 to 4.9 ± 0.9 in controls. Tumor growth inhibition was evidenced using a calliper from day 24 and associated to a decrease in PG content in treated tumor tissues (confirmed by histology). Conclusions: This work demonstrated two proofs of concept: (1) biphosphonate therapy could be a promising therapeutic approach for chondrosarcoma; (2) 99mTc-NTP 15-5 is expected to offer a novel imaging modality for the in vivo evaluation of the extracellular matrix features of chondrosarcoma, which could be useful for the follow-up and quantitative assessment of proteoglycan ‘downregulation’ associated to the response to therapeutic attempts

Promising pre-clinical validation of targeted radionuclide therapy using a [131I] labelled iodoquinoxaline derivative for an effective melanoma treatment

Targeted internal radionuclide therapy (TRT) would be an effective alternative to current therapies for dissemi- nated melanoma treatment. At our institution, a class of iodobenzamides has been developed as potent melanoma- seeking agents. This review described the preclinical vali- dations of a quinoxaline derivative molecule (ICF01012) as tracer for TRT application. It was selected for its high, specific and long-lasting uptake in tumour with rapid clear- ance from non-target organs providing suitable dosimetry parameters for TRT. Extended in vivo study of metabolic profiles confirmed durable tumoural concentration of the unchanged molecule form. Moreover melanin specificity of ICF01012 was determined by binding assay with syn- thetic melanin and in vivo by SIMS imaging. Then, we showed in vivo that [131I] ICF01012 treatment drastically inhibited growth of B16F0, B16Bl6 and M4Beu tumours whereas [131I] NaI or unlabelled ICF01012 treatment was without significant effect. Histological analysis showed that residual tumour cells exhibit a significant loss of aggres- siveness after treatment. This anti-tumoural effect was associated with a lengthening of the treated-mice survival time and an inhibition of lung dissemination for B16Bl6 model. Results presented here support the concept of TRT using a [131I] labelled iodoquinoxaline derivative for an effective melanoma treatment.<br /

Design, synthesis, and biological activities of conformationally restricted analogs of primaquine with a 1,10-phenanthroline framework

A series of primaquine analogs was prepared, according to a conformationally restricted conformation of primaquine. In vitro antiplasmodial activities were evaluated and showed that all compounds were active on different strains of Plasmodium falciparum. In particular compounds 5 and 15 possessing a methoxy group were more active than was primaquine. Furthermore, analog 5 displayed good in vitro gametocytocidal activity. In addition selectivity indexes were calculated in respect with cytotoxic activities on Vero cell lines

Functionalization of gold nanoparticles by SPAAC reaction for PDT treatment of Dubreuilh’s melanoma.

International audienc

Dosimétrie chez le lapin d'[131I]ICF01012 en vue de son utilisation pour le traitement du mélanome métastatique par radiothérapie interne vectorisée

National audienc

Synthesis and preliminary biological evaluations of PSMA-targeted NIR upconverting nanoparticles for optical/scintigraphic imaging of prostate cancer.

International audienc

Preliminary evaluations of PSMA-targeted NIR upconverting nanoparticles for dual scintigraphic/fluorescence-guided surgery in prostate cancer.

International audienc

Internal dosimetry through GATE simulations of preclinical radiotherapy using melanin-targeting ligand

International audienceThe GATE Monte Carlo simulation platform based on the Geant4 toolkit is under constant improvement for dosimetric calculations. In this study, we explore its use for the dosimetry of the preclinical targeted radiotherapy of melanoma using a new specific melanin-targeting radiotracer labeled with iodine 131. Calculated absorbed fractions and S values for spheres and murine models (digital and CT-scan-based mouse phantoms) are compared between GATE and EGSnrc Monte Carlo codes considering monoenergetic electrons and the detailed energy spectrum of iodine 131. The behavior of Geant4 standard and low energy models is also tested. Following the different authors' guidelines concerning the parameterization of electron physics models, this study demonstrates an agreement of 1.2% and 1.5% with EGSnrc, respectively, for the calculation of S values for small spheres and mouse phantoms. S values calculated with GATE are then used to compute the dose distribution in organs of interest using the activity distribution in mouse phantoms. This study gives the dosimetric data required for the translation of the new treatment to the clinic