Ovarian cancer has the highest mortality rate of all gynecological malignancies, due to inadequate treatment strategies and poor early diagnosis. Intraperitoneal (IP) chemotherapy administered on an intermittent schedule has been pursued for ovarian cancer treatment. However, local toxicities and complications associated with indwelling IP catheters required to deliver the chemotherapeutics have been documented. Furthermore, shortening or completely removing treatment-free periods between each chemotherapy cycle has shown improved efficacy compared to intermittent chemotherapy. The focus of this thesis was to develop and characterize a biocompatible and biodegradable IP injectable depot sustained drug delivery system as a new treatment strategy for ovarian cancer. A polymer-lipid injectable formulation (PoLigel) was developed and used for sustained docetaxel (DTX) delivery. The PoLigel resulted in homogeneous DTX peritoneal distribution and sustained plasma levels in healthy mice, which was in contrast to Taxotere®, the clinically used formulation of DTX. Sustained plasma, tissue, tumor and ascites DTX concentrations were observed in mice bearing IP SKOV3 tumors or ID8 ascites over a 3 week period following IP administration of the PoLigel. The intratumoral distribution and tumor penetration of DTX in subcutaneous (SC) and IP SKOV3 tumors were characterized. DTX distributed more towards the tumor core and diffused 1.5 fold further from blood vessels of the IP tumors compared to the SC tumors. The high efficacy observed in the IP SKOV3 and ID8 models and the SC SKOV3 model was attributed to favorable drug distribution at the whole-body, peritoneal and intratumoral levels in combination with local and systemic sustained drug exposure. Sustained chemotherapy with DTX alone and in combination with a drug efflux transporter inhibitor was investigated in multidrug resistant (MDR) ovarian cancer. In vitro, combination delivery via the PoLigel resulted in more apoptosis, greater intracellular accumulation of DTX, and lower DTX efflux in MDR ovarian cancer cells. Sustained combination chemotherapy was more than twice as efficacious as intermittent Taxotere® treatment in MDR ovarian cancer. Significant anti-tumor efficacy was also observed in the MDR model following sustained DTX chemotherapy compared to intermittent Taxotere®. Overall, results presented here encourage the clinical investigation of IP sustained chemotherapy for ovarian cancer treatment.

Ovarian cancer has the highest mortality rate of all gynecological malignancies, due to inadequate treatment strategies and poor early diagnosis. Intraperitoneal (IP) chemotherapy administered on an intermittent schedule has been pursued for ovarian cancer treatment. However, local toxicities and complications associated with indwelling IP catheters required to deliver the chemotherapeutics have been documented. Furthermore, shortening or completely removing treatment-free periods between each chemotherapy cycle has shown improved efficacy compared to intermittent chemotherapy. The focus of this thesis was to develop and characterize a biocompatible and biodegradable IP injectable depot sustained drug delivery system as a new treatment strategy for ovarian cancer. A polymer-lipid injectable formulation (PoLigel) was developed and used for sustained docetaxel (DTX) delivery. The PoLigel resulted in homogeneous DTX peritoneal distribution and sustained plasma levels in healthy mice, which was in contrast to Taxotere®, the clinically used formulation of DTX. Sustained plasma, tissue, tumor and ascites DTX concentrations were observed in mice bearing IP SKOV3 tumors or ID8 ascites over a 3 week period following IP administration of the PoLigel. The intratumoral distribution and tumor penetration of DTX in subcutaneous (SC) and IP SKOV3 tumors were characterized. DTX distributed more towards the tumor core and diffused 1.5 fold further from blood vessels of the IP tumors compared to the SC tumors. The high efficacy observed in the IP SKOV3 and ID8 models and the SC SKOV3 model was attributed to favorable drug distribution at the whole-body, peritoneal and intratumoral levels in combination with local and systemic sustained drug exposure. Sustained chemotherapy with DTX alone and in combination with a drug efflux transporter inhibitor was investigated in multidrug resistant (MDR) ovarian cancer. In vitro, combination delivery via the PoLigel resulted in more apoptosis, greater intracellular accumulation of DTX, and lower DTX efflux in MDR ovarian cancer cells. Sustained combination chemotherapy was more than twice as efficacious as intermittent Taxotere® treatment in MDR ovarian cancer. Significant anti-tumor efficacy was also observed in the MDR model following sustained DTX chemotherapy compared to intermittent Taxotere®. Overall, results presented here encourage the clinical investigation of IP sustained chemotherapy for ovarian cancer treatment.

Les lipides « switch » - bascules - appartiennent à la famille des matériaux sensibles à un stimulus. Quand ces lipides bascules sont incorporés aux nanoparticules lipidiques (LNP), ils permettent la délivrance contrôlée grâce à un changement de conformation activé par une baisse de pH. Des expériences précédentes avaient démontré que les LNP bascules ont transfecté le petits ARN interférents (siRNA) in vitro et in vivo, silençant la protéine fluorescente verte (GFP) et la protéine hépatique Facteur VII, respectivement. La double administration de micro ARN (miRNA) et d'agent anticancéreux melphalan a également été réalisée par les LNP bascule sur un modèle de rétinoblastome murin. Ces résultats prometteurs nous ont encouragé à élargir les applications de LNP bascules en tant que vecteur de siRNA. De plus, le mécanisme par lequel les LNP bascules induisent la déstabilisation de la membrane et la libération de matériaux encapsulé au milleu acide reste obscur. La compréhension de ce mécanisme est cruciale pour cerner les avantages et les limites des LNP bascules, pour proposer des futures applications et pour prévenir leur toxicité. Dans ce mémoire, nous avons comme objectif d’évaluer le potentiel des LNP bascules pour le traitement du cancer. Nous avons évalué les LNP bascules comme vecteur de livraison du siRNA ciblant l'une des protéines cancéreuses les plus spécifiques découvertes à ce jour, la survivine. En parallèle, nous avons étudié le comportement biophysique des membranes contenant des lipides bascules dans des vésicules de taille micromètrique. Dans la première étude, nous avons démontré que les LNP bascules ont permis le silençage de la survivine dans une gamme de lignées cellulaires cancéreuses (poumon, cervical, ovaire, sein, côlon, rétinoblastome). Dans les cellules du rétinoblastome humain (Y79), nous avons examiné plusieurs agents cytotoxiques utilisés en clinique quant à leur synergie avec le silençage de la survivine: melphalan, topotécan, téniposide et carboplatine. Le prétraitement avec les LNP chargées de siRNA-survivine a amélioré de manière synergique la cytotoxicité du carboplatine et du melphalan mais dans une moindre mesure celle du topotécan et du téniposide. Cet effet était spécifique aux cellules cancéreuses car les cellules saines (ARPE.19) n'exprimaient pas de survivine. L'inhibition de la survivine par silençage de siRNA s'est révélée plus spécifique et moins dommageable pour les cellules saines (ARPE.19) que le YM155, un inhibiteur moléculaire de la survivine. Dans la deuxième étude, nous avons observé par microscopie confocale que les lipides bascules induisaient rapidement le stress, la fission et une courbure positive dans les membranes des vésicules unilamellaires géantes lorsqu'elles étaient exposées à des conditions acides. La dynamique de la membrane a été confirmée par des expériences de diffusion dynamique de la lumière (DLS) et de fuite de calcéine. Ces phénomènes ont également été observés lorsque des lipides bascules ont été incorporés dans une membrane hybride polymère/lipide, fournissant des propriétés sensibles au pH aux vésicules hybrides. À notre connaissance, c'est la première fois qu'une vésicule hybride sensible au pH est reportée. Nos résultats corroborent l'applicabilité des LNP bascules en tant qu'agents de vectorisation des siRNA pour le traitement du cancer grâce au silençage de la survivine, en particulier comme adjuvant à la chimiothérapie. L'investigation biophysique a révélé que les lipides bascules agissent sur la fluidité de la membrane, en particulier à pH acide. Cette sélectivité en pH garantit leur biocompatibilité à pH neutre ainsi que la libération efficace et rapide de leur cargo à pH acide. La compatibilité avec les vésicules hybrides polymère/lipide ouvre de nouvelles applications au niveau de vésicules biomimétiques et l'administration de médicaments. / Cationic switchable lipids belong to the class of stimuli-responsive materials. When incorporated in lipid nanoparticles (LNP), switchable LNP promote pH-triggered delivery of payload based on a molecular switch mechanism. Previous studies have demonstrated that switchable LNP successfully delivered small interferring RNA (siRNA) in vitro and in vivo, promoting the silencing of a reporter Green Fluorescencen Protein (GFP) protein and liver-produced factor VII, respectively. Dual delivery of micro RNA (miRNA) and anticancer agent melphalan was also achieved through switchable LNP in a retinoblastoma rat model. These promising results encouraged us to enlarge the applications of switchable LNP as siRNA carrier. Moreover, the mechanism whereby switchable LNP mediate acid-triggered membrane destabilization and, thus, payload release remains elusive. Understanding this mechanism is crucial to draw the advantages and limitations of switchable LNP, and to tailor their future applications and prevent their potential toxicity. In this dissertation, we aimed to further understand the potential of switchable LNP for cancer treatment. We assessed switchable LNP as a siRNA delivery carrier by targeting one of the most specific cancer protein discovered to date, survivin. Meanwhile, we investigated the biophysical behavior of switchable-lipid containing membranes in micron-sized vesicles. In the first study, we demonstrated that switchable LNP efficiently silenced survivin in a range of cancer cell line models (lung, cervical, ovary, breast, colon, retinoblastoma). In retinoblastoma (RB) cells (Y79), several clinically used cytotoxic agents were screened for their synergy with survivin silencing: melphalan, topotecan, Teniposide, and carboplatin. Pretreatment with LNP loaded with siRNA targeted against survivin synergistically enhanced the cytotoxicity of carboplatin and melphalan but in lesser extent topotecan and teniposide. This effect was specific to cancer cells since healthy cells (ARPE.19) did not express survivin. Survivin inhibition through siRNA silencing revealed more specific and less damageable for healthy cells (ARPE.19) than a molecular approach, such as YM155. In the second study, we observed by confocal microscopy that switchable lipids rapidly induced stress, fission, and positive curvature in giant unilamellar vesicles’ membranes when submitted to acidic conditions. The membrane dynamics was confirmed by dynamic light scattering and calcein leakage experiments. Remarkably, these phenomena were also observed when switchable lipids were embedded into a hybrid polymer/lipid membrane, providing pH-sensitive properties to hybrid vesicles. To the best of our knowledge, this is the first time a pH-sensitive hybrid vesicle is reported. Our findings corroborate with the applicability of switchable LNP as siRNA delivery agents for cancer treatment through survivin silencing, especially as an adjuvant to chemotherapy. The biophysical investigation revealed that the switchable lipids act on the membrane fluidity, specifically at acidic pH. This pH selectivity guarantees their biocompatibility at neutral pH as well as its efficient and quick release of their cargo at acidic pH. Their compatibility with hybrid polymer/lipid vesicles opens new applications in biomimetic vesicles and drug delivery.