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<p>Pancreatic ductal adenocarcinoma is an especially deadly disease having the lowest 5-year survival rate of any major cancer at just 11%. As in many cancers, systemically-delivered chemotherapy forms the backbone of clinical treatment. However, limitations of systemic delivery exacerbated by the unique desmoplastic and avascular microenvironment surrounding the pancreatic tumor cells result in the failed efficacy of current treatments. The high stromal content in the microenvironment, which is especially overabundant in hyaluronic acid, is thought to physically impede drug perfusion into the tissue. Thus, there is clearly a <strong>critical need</strong> to develop novel treatments for pancreatic ductal adenocarcinoma that can overcome these drug delivery barriers. Long-acting injectable implants offer an attractive drug delivery method that can provide <em><strong>sustained</strong></em> drug release directly at the <em><strong>local</strong></em> targeted site, rather than transient, systemic release. Here we use in situ forming implants (ISFIs), which are a low-viscosity solution outside of the body but transition into a solid drug-eluting depot after injection into an aqueous environment. Our <strong>objective</strong> is to develop and characterize an ISFI that can provide sustained release of bioactive hyaluronidase for use as an intratumoral injection to degrade hyaluronic acid in pancreatic tumors. This work was accomplished in four aims. First, a method was developed using diffusion-weighted MRI for noninvasive characterization of the implants. Second, because hyaluronidase is a protein drug, we studied factors affecting protein release from ISFIs, focusing on external factors of the injection site. Third, we showed that basic salt additives can be used to neutralize the acidic environment created by the implants which may improve protein stability. Finally, we formulated an implant to provide sustained release of hyaluronidase and demonstrated retention of its bioactivity both <em>in vitro</em> and <em>ex vivo</em>.</p>

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La prise en charge des patients souffrant d’un trouble mental justifie une meilleure compréhension des mécanismes influençant les comportements des patients et des cliniciens vis-à-vis des stratégies thérapeutiques. Le principal objectif de cette thèse est d’étudier et d’identifier le rôle des attitudes des patients et des cliniciens vis-à-vis du comportement d’usage d’une thérapeutique. Pour cela, nous avons réalisé plusieurs études permettant d’appréhender cette problématique dans différentes pathologies et envers différentes thérapeutiques.Concernant les attitudes des patients envers leur traitement, nous avons détaillé un travail visant à évaluer les croyances de patients souffrant de schizophrénie envers leur antipsychotique et une étude qualitative sur les attitudes des patients bipolaires envers leur prise en charge en phase d’euthymie. Nous avons montré l’impact des attitudes négatives sur le niveau d’observance ou d’adhésion des patients à leur prise en charge et l’intérêt de cibler des stratégies de prise en charge individualisées visant à améliorer ces attitudes. Concernant les psychiatres, nous avons présenté une étude évaluant les attitudes des cliniciens vis-à-vis des recommandations professionnelles ainsi qu’un travail concernant leurs attitudes envers les antipsychotiques d’action prolongée. Certaines attitudes des psychiatres apparaissaient associées à une plus faible utilisation des recommandations ou des formulations d’action prolongée. Nos résultats montrent ainsi que l’observance ou l’adhésion des patients à une prise en charge ou le choix thérapeutique des cliniciens sont sous-tendus par leurs attitudes. L’étude des attitudes dans le domaine de la santé mentale apparaît comme une étape indispensable dans la compréhension de certains comportements d’usage des thérapeutiques. Les données issues des travaux présentés mais aussi d’études récentes permettent d’envisager un changement de paradigme dans l’appréhension des comportements d’observance des patients et de décision médicale des cliniciens dans le choix d’une thérapeutique centré sur leurs attitudes. / The management of patients with severe mental illnesses needs a better understanding of thefactors affecting the behaviours of clinicians and patients toward therapeutic strategies.The main objective of this thesis was to assess and identify the role of the clinician’s attitudes and patients’ attitudes toward the medication use behaviour. We conducted several studies to address this point in different mental disorders and for different type of treatment. Concerning the patients ‘attitudes toward treatment, we reported data from a study assessing the beliefs toward antipsychotics of schizophrenic patients and from a qualitative study assessing the patient’s attitudes toward the management of bipolar disorder in euthymic periods. We showed that the negative attitudes had a marked impact on the level of adherence of patients and could determine individual targets of interventions to improve them. Concerning the psychiatrists, we reported two studies assessing the clinician’s attitudes toward guidelines and long-acting injectable antipsychotics. Some specific attitudes were associated with a lower use of guidelines or long-acting formulations. These findings showed that the adherence of patient to treatment and the medical decisions of clinicians were related to their attitudes. The assessment of attitudes or beliefs in the field of mental health appears to be an essential step to promote a better comprehension of some treatment use behaviours. Our results and from other recent studies support a new paradigm for the patient adherence to treatment and the medical decision of clinicians focused on their attitudes as predicting variables.