Recent advancements in pharmaceutical technology based on principles of nanotechnology, polymer chemistry, and biomedical engineering have resulted in the creation of novel drug delivery systems with the potential to revolutionize current strategies in cancer chemotherapy. In oncology, realization of significant improvements in therapeutic efficacy requires minimization of drug exposure to healthy tissues and concentration of the drug within the tumor. As such, encapsulation of chemotherapeutic agents inside nanoparticles capable of enhancing tumor-targeted drug delivery is a particularly promising innovation. Yet, initial investigations into the intratumoral fate of nanomedicines have suggested that they may be heterogeneously distributed and achieve limited access to cancer cells located distant from the tumor vasculature. As such, uncovering the determinants of nanoparticle transport at the intratumoral level is critical to the development of optimized delivery vehicles capable of fully exploiting the therapeutic potential of nanomedicines. In this work, the chemotherapeutic agent, docetaxel (DTX), was incorporated into nano-sized, biocompatible PEG-b-PCL block copolymer micelles (BCMs). Encapsulation of DTX in micelles via chemical conjugation or physical entrapment resulted in a dramatic increase in drug solubility and customizable drug release rate. The use of multicellular tumor spheroids (MCTS) was established as a viable platform for assessing the efficacy and tumor tissue penetration of nanomedicines in vitro. A series of complementary assays was validated for analysis of DTX-loaded micelle (BCM+DTX) toxicity in monolayer and spheroid cultures relative to Taxotere®. Cells cultured as spheroids were less responsive to treatment relative to monolayer cultures due to mechanisms of drug resistance associated with structural and microenvironmental properties of the 3-D tissue. Computational, image-based methodologies were used to assess the spatial and temporal penetration of BCMs in spheroids and corresponding human tumor xenografts. Using this approach, the tumor penetration of micelles was found to be nanoparticle-size-, tumor tissue type- and time- dependent. Furthermore, spheroids were found to be a valuable platform for the prediction of trends in nanoparticle transport in vivo. Overall, the results reported herein serve to demonstrate important determinants of nanoparticle intratumoral transport and to establish computational in vitro and in vivo methodologies for the rational design and optimization of nanomedicines.

Recent advancements in pharmaceutical technology based on principles of nanotechnology, polymer chemistry, and biomedical engineering have resulted in the creation of novel drug delivery systems with the potential to revolutionize current strategies in cancer chemotherapy. In oncology, realization of significant improvements in therapeutic efficacy requires minimization of drug exposure to healthy tissues and concentration of the drug within the tumor. As such, encapsulation of chemotherapeutic agents inside nanoparticles capable of enhancing tumor-targeted drug delivery is a particularly promising innovation. Yet, initial investigations into the intratumoral fate of nanomedicines have suggested that they may be heterogeneously distributed and achieve limited access to cancer cells located distant from the tumor vasculature. As such, uncovering the determinants of nanoparticle transport at the intratumoral level is critical to the development of optimized delivery vehicles capable of fully exploiting the therapeutic potential of nanomedicines. In this work, the chemotherapeutic agent, docetaxel (DTX), was incorporated into nano-sized, biocompatible PEG-b-PCL block copolymer micelles (BCMs). Encapsulation of DTX in micelles via chemical conjugation or physical entrapment resulted in a dramatic increase in drug solubility and customizable drug release rate. The use of multicellular tumor spheroids (MCTS) was established as a viable platform for assessing the efficacy and tumor tissue penetration of nanomedicines in vitro. A series of complementary assays was validated for analysis of DTX-loaded micelle (BCM+DTX) toxicity in monolayer and spheroid cultures relative to Taxotere®. Cells cultured as spheroids were less responsive to treatment relative to monolayer cultures due to mechanisms of drug resistance associated with structural and microenvironmental properties of the 3-D tissue. Computational, image-based methodologies were used to assess the spatial and temporal penetration of BCMs in spheroids and corresponding human tumor xenografts. Using this approach, the tumor penetration of micelles was found to be nanoparticle-size-, tumor tissue type- and time- dependent. Furthermore, spheroids were found to be a valuable platform for the prediction of trends in nanoparticle transport in vivo. Overall, the results reported herein serve to demonstrate important determinants of nanoparticle intratumoral transport and to establish computational in vitro and in vivo methodologies for the rational design and optimization of nanomedicines.

Existing methods of treating glioma are not effective for eradicating the disease. Therefore, new and innovative methods of treatment alone or in combination with existing therapies are necessary. Delivery of therapeutic agents through delivery carriers such as liposomes diminishes the harmful effects of the agent in healthy tissues and allows increased accumulation in the tumor. In addition, targeted chemotherapy using liposomes provides the opportunity for further increase in drug accumulation in tumor. However, the current targeting strategies suffer accelerated plasma clearance and are not advantageous in improving efficacy. The search for new tumor targets, novel ligands, new strategies for targeting, and particle stabilization will advance our ability to improve delivery at the tumor level while decreasing toxicity to normal tissues. The global objective of this thesis was to improve the status of current liposomal therapy to achieve higher efficacy in tumors. Here, we show a novel mechanism to increase targeting to tumor while uncompromising on the long circulation of stealth liposomes. Long circulation is essential for passive accumulation of the nanocarriers due to EPR effect, in order to see benefits of targeting. Using phage display technique, a variety of tumor specific peptides were identified for use as targeting moieties. One potential advantage of the approach proposed here is the rapid identification of patient tumor specific peptide that evades the RES. This could lead to the development of a nanocarrier system with high avidity and selectivity for tumors. Therefore, tumor accumulation of the targeted formulations will be higher than that of non‐targeted liposomes due to increased drug retention at the tumor site and uncompromised blood residence time.In addition, it has been shown that the distribution of nanocarriers, spatially within the tumor, is limited that might further hinder the distribution of the encapsulated drug, thereby limiting efficacy. It is necessary to release the drug from within the nanocarrier to promote increased efficacy. Here, we were able to address the problem of drug diffusion within the tumor interstitium using a combination therapy employing a remotely triggered thermosensitive liposomal chemotherapeutic. We fabricated a thermosensitive liposomal nanocarrier that maintained its stability at physiological temperature to minimize toxicity to healthy cells. We, then, showed a remote triggering mechanism mediated by gold nanorods heated via NIR can help in achieving precise control over the desired site for drug release. These strategies enabled increased drug availability at the tumor site and contributed to tumor retardation. Additionally, we show that the synergistic therapy employing gold nanorods and thermosensitive liposomes may have great potential to be translated to the clinic.

Les glioblastomes sont les tumeurs cérébrales les plus fréquentes avec une incidence en France de l'ordre de 4 nouveaux cas par an et pour 100 000 habitants (2400/ an). Le traitement standard pharmacologique des glioblastomes nouvellement diagnostiqués consiste en première ligne en une administration de témozolomide (75 mg/m2/j) pendant la radiothérapie, suivie d’une consolidation de 6 cycles. Cependant, malgré ce traitement, la médiane de survie n’est que de 15 mois et de 3 à 9 mois pour les rechutes. De nouvelles approches thérapeutiques sont donc indispensables. Parmi elles, ont été évalués le recours à d’autres chimiothérapies (irinotecan) et à l’inhibition de l’angiogénèse. L'angiogenèse est en effet un processus critique dans la progression GBM. L'inhibition de l'angiogenèse, induisant une réduction des vaisseaux sanguins, permet une diminution de l’apport des nutriments et d'oxygène à la tumeur. De manière générale, l’efficacité des traitements du glioblastome est soumise, dans un premier temps, à leur passage intra-cérébral au travers de la barrière hémato-encéphalique (BHE). L’objectif de notre travail était d’une part d’étudier l’impact de l’expression du transporteur d’efflux ABCB1 sur la distribution cérébrale du témozolomide (TMZ) et de l’irinotecan (CPT-11), et d’autre part, d’évaluer le rôle du bevacizumab (BVZ)(inhibiteur de l’angiogénèse) dans la modulation du passage intra-cérébral et intra-tumoral du TMZ et du CPT-11. A l'aide d'une étude pharmacocinétique comparative chez les souris CF1 mdr1a (+/+) et les souris CF1 mdr1a (-/-), nous avons mis en évidence un efflux actif du TMZ, du CPT-11 et de son métabolite actif le SN-38 du cerveau vers le plasma, impliquant ABCB1 au niveau de la BHE. Nous avons également démontré in vivo que le TMZ s'accumule dans la tumeur cérébrale et que le prétraitement par BVZ augmente la distribution tumorale de TMZ. En revanche, le BVZ n’a montré aucun effet sur la distribution cérébrale ou tumorale du CPT-11. Le BVZ apparaitrait donc comme un moyen intéressant d’augmenter la distribution intratumorale du TMZ. Dans ce même objectif, une collaboration initiée dans le cadre de cette thèse a permis de mettre en évidence l’intérêt de l’utilisation d’ultrasons dans l’ouverture de la BHE et l’amélioration de la distribution cérébrale des médicaments. / Glioblastomas are the most common brain tumors occurring in France with an incidence of 4 new cases per year per 100 000 population (2400/year). The gold standard pharmacological treatment of newly diagnosed glioblastoma relies on temozolomide administration (75 mg/m2/d) concomitant to radiotherapy, followed by six cycles consolidation. However, despite this treatment, the median survival is only 15 months and relapse occurs within 3 to 9 months. New therapeutic approaches are needed. Among them, other chemotherapies (irinotecan) and inhibition of angiogenesis were explored. Angiogenesis is a critical process in GBM progression. Inhibition of angiogenesis, inducing a reduction of the blood vessels, reduces supply of nutrients and oxygen to the tumor. The effectiveness of GBM treatment is subjected to intra-brain diffusion through the blood-brain barrier. The objective of this study was firstly to study the impact of efflux transporter ABCB1 brain expression on temozolomide (TMZ) and irinotecan (CPT-11) brain distribution, and secondly, to assess the role of bevacizumab (BVZ)(angiogenesis inhibitor) in the modulation of TMZ and CPT-11 brain and tumor distribution. Using a comparative pharmacokinetic study in CF1 mdr1a (+/+) and CF1 mdr1a (-/-) mice, we demonstrated an active efflux of TMZ, CPT-11 and its active metabolite SN-38 from the brain to the plasma involving ABCB1. We also demonstrated in vivo that TMZ accumulates in brain tumor and BVZ pretreatment increased TMZ tumor distribution. However no effect of BVZ on CPT-11 brain or tumor distribution was evidenced. Therefore BVZ would appear to be an interesting way to increase TMZ tumor distribution. The same objective was pursued through a different approach using ultrasound unfocused to open the BBB (Carthera collaboration).