Peptide-Alkoxyamine Drugs: An Innovative Approach to Fight Schistosomiasis: "Digging Their Graves with Their Forks".

The expansion of drug resistant parasites sheds a serious concern on several neglected parasitic diseases. Our recent results on cancer led us to envision the use of peptide-alkoxyamines as a highly selective and efficient new drug against schistosome adult worms, the etiological agents of schistosomiasis. Indeed, the peptide tag of the hybrid compounds can be hydrolyzed by worm's digestive enzymes to afford a highly labile alkoxyamine which homolyzes spontaneously and instantaneously into radicals-which are then used as a drug against Schistosome adult parasites. This approach is nicely summarized as digging their graves with their forks. Several hybrid peptide-alkoxyamines were prepared and clearly showed an activity: two of the tested compounds kill 50% of the parasites in two hours at a concentration of 100 µg/mL. Importantly, the peptide and alkoxyamine fragments that are unable to generate alkyl radicals display no activity. This strong evidence validates the proposed mechanism: a specific activation of the prodrugs by the parasite proteases leading to parasite death through in situ alkyl radical generation.

Hybrid Peptide-Alkoxyamine Drugs: A Strategy for the Development of a New Family of Antiplasmodial Drugs.

The emergence and spread of drug-resistant Plasmodium falciparum parasites shed a serious concern on the worldwide control of malaria, the most important tropical disease in terms of mortality and morbidity. This situation has led us to consider the use of peptide-alkoxyamine derivatives as new antiplasmodial prodrugs that could potentially be efficient in the fight against resistant malaria parasites. Indeed, the peptide tag of the prodrug has been designed to be hydrolysed by parasite digestive proteases to afford highly labile alkoxyamines drugs, which spontaneously and instantaneously homolyse into two free radicals, one of which is expected to be active against P. falciparum. Since the parasite enzymes should trigger the production of the active drug in the parasite's food vacuoles, our approach is summarized as "to dig its grave with its fork". However, despite promising sub-micromolar IC50 values in the classical chemosensitivity assay, more in-depth tests evidenced that the anti-parasite activity of these compounds could be due to their cytostatic activity rather than a truly anti-parasitic profile, demonstrating that the antiplasmodial activity cannot be based only on measuring antiproliferative activity. It is therefore imperative to distinguish, with appropriate tests, a genuinely parasiticidal activity from a cytostatic activity.

Development of a near infrared protein nanoprobe targeting Thomsen-Friedenreich antigen for intraoperative detection of submillimeter nodules in an ovarian peritoneal carcinomatosis mouse model.

The epithelial ovarian cancer is one of the most lethal gynecological malignancy due to its late diagnostic and many relapses observed after first line of treatment. Once diagnose, the most important prognostic factor is the completeness of cytoreductive surgery. To achieve this goal, surgeons have to pinpoint and remove nodules, especially the smallest nodules. Recent advances in fluorescence-guided surgery led us to develop a recombinant lectin as a nanoprobe for the microscopic detection of nodules in the peritoneal cavity of tumor-bearing mice. This lectin has an intrinsic specificity for a carcinoma-associated glycan biomarker, the Thomsen-Friedenreich antigen. In this study, after its labelling by a near infrared dye, we first demonstrated that this nanoprobe allowed indirect detection of nodules already implanted in the peritoneal cavity, through tumor microenvironment targeting. Secondly, in a protocol mimicking the scattering of cells during surgery, we obtained a direct and long-lasting detection of tumor cells in vivo. This lectin as already been described as a nanocontainer able to do targeted delivery of a therapeutic compound to carcinoma cells. Future developments will focus on the combination of the nanoprobe and nanocontainer aspects in an intraperitoneal nanotheranostic approach.

A protein nanocontainer targeting epithelial cancers: rational engineering, biochemical characterization, drug loading and cell delivery.

The development of drug delivery and imaging tools is a major challenge in human health, in particular in cancer pathologies. This work describes the optimization of a protein nanocontainer, belonging to the lectin protein family, for its use in epithelial cancer diagnosis and treatment. Indeed, it specifically targets a glycosidic marker, the T antigen, which is known to be characteristic of epithelial cancers. Its quaternary structure reveals a large hydrated inner cavity able to transport small therapeutic molecules. Optimization of the nanocontainer by site directed mutagenesis allowed controlling loading and release of confined drugs. Doxorubicin confinement was followed, both theoretically and experimentally, and provided a proof of concept for the use of this nanocontainer as a vectorization system. In OVCAR-3 cells, a human ovarian adenocarcinoma cell line that expresses the T antigen, the drug was observed to be delivered inside late endosomes/lysosomes. These results show that this new type of vectorization and imaging device opens new exciting perspectives in nano-theranostic approaches.