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Imagerie quantitative de bioluminescence appliquée à un modèle murin syngénique de lymphome exprimant le CD20 humain : analyses de l'influence du volume tumoral sur la réponse au traitement par un anticorps monoclonal, le rituximab, et de l'effet thérapeutique de neutrons et de nanoparticules chargées.

Abstract : Tumor burden influence on individual response to treatment, with a monoclonal antibody: the rituximab, by quantitative bioluminescence imaging in a syngenic murine model of lymphoma expressing human CD20.

In the last years, owing to advances carried out in the humanization of recombinant monoclonal antibodies (rmAb), these have seen an increase in their therapeutic use, especially in the treatment of cancer. Among these rmAb, rituximab (Mabthera®) was the first to get an approval in France and in the United Sates. This is a chimeric antibody of the IgG1 kappa type specific for the CD20 surface antigen expressed by more than 95 percent of B cells lymphomas. Rituximab used alone or in association with chemotherapy has shown its efficiency in the treatment of low and high grade lymphomas. Nevertheless, when it is used alone in therapy, 30 to 50% of the patients didn't respond to the treatment. Several hypotheses were evoked to explain this variability in response to treatment, among which importance of the tumor burden, a low level of CD20 expression, presence of soluble forms of CD20 or weak serum concentrations of rituximab. Thus, exposure to the drug and the tumor burden value could be factors of therapeutic variability to take into account individually to optimize the treatment of the patients reached of non Hodgkin's lymphoma.

The overall objective of this work of thesis was to analyze the respective role of tumor burden and pharmacokinetic parameters in the response to the rituximab by using systems of imagery adapted to murine models and to cancerology.

In a first part of development of the model we used a T lymphoma cell line (EL4) syngenic of mouse C57Bl6J, transduted by the human CD20 and transfected with luciferase gene (EL4-huCD20-Luc). We then defined the experimental conditions (cells number, route of administration, amount of potassium salt luciferin, mice strain, examinations periodicity) allowing to reproduce in the mouse the development of an aggressive and disseminated lymphoma with larges B cells and lethal within 30 to 40 days after inoculation. We developed a quantification method of the intensity of bioluminescence of the tumoral sources by taking into account the absorption coefficient of the light depending of the anatomical localization of each lymphoma tumor.

In a second part we studied the therapeutic effect of the rituximab on this lymphoma model. Only one injection of rituximab with gradually increasing amount (150 µg to 1000 µg) was carried out 13 days after the lymphoma cells inoculation (time necessary to the development of a quantifiable lymphoma by bioluminescence imaging). The circulating concentration of rituximab was evaluated by an ELISA method adapted to the analysis of small plasma volumes and to a murine model. In this model, we showed a relation between the administered dose and the survival of the mice; the totality of the mice being surviving to the amount of 1000 µg. It is with 500 µg that we found the greatest variability in response to the rituximab with approximately 23% of mice in complete response, 59% in partial response and 18% with a progressive disease. For the whole of the mice receiving this amount, we precisely determined tumor burden at the time of the rituximab injection and evaluated the concentrations to the waning of the treatment. We thus showed that there was a significant relation between tumor burden at the time of the injection and response to the rituximab; mice having lowest tumor burden having a better response and a prolonged survival. The analysis of the rituximab concentrations in the course of time enabled us to show a very important variability of exposure to the rituximab similar to the observation made for the human. We realized a model of the rituximab concentrations and of the tumors evolution, the construction of a concentration/effect (PK-PD) model allowing us to show the existence of a relation between the effectiveness of the rituximab and tumor burden before treatment.

Finally in a third part we used the cellular model EL4-huCD20-Luc in order to evaluate in vitro the use of gadolinium oxide particles or boron and gadolinium oxide particles. We checked the properties of contrast agents of these particles for the magnetic resonance imagery. We also showed the important radiating effect of these particles during an irradiation under a beam of neutrons after a step of insourcing of the particles within the cells. These results are very promising.
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https://tel.archives-ouvertes.fr/tel-00369130
Contributor : David Dayde <>
Submitted on : Wednesday, March 18, 2009 - 2:51:57 PM
Last modification on : Friday, October 23, 2020 - 4:34:06 PM
Long-term archiving on: : Tuesday, June 8, 2010 - 9:38:19 PM

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  • HAL Id : tel-00369130, version 1

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David Dayde. Imagerie quantitative de bioluminescence appliquée à un modèle murin syngénique de lymphome exprimant le CD20 humain : analyses de l'influence du volume tumoral sur la réponse au traitement par un anticorps monoclonal, le rituximab, et de l'effet thérapeutique de neutrons et de nanoparticules chargées.. Immunologie. Université François Rabelais - Tours, 2007. Français. ⟨tel-00369130⟩

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