OBJECTIVE: One of the major issues in current radiotherapy (RT) is the normal tissue toxicity. A smart combination of agents within the tumor would allow lowering the RT dose required while minimizing the damage to healthy tissue surrounding the tumor. We chose gold nanoparticles (GNPs) and docetaxel (DTX) as our choice of two radiosensitizing agents. They have a different mechanism of action which could lead to synergistic effect. Our first goal was to assess the variation in GNP uptake, distribution, and retention in the presence of DTX. Our second goal was to assess the therapeutic results of the triple combination, RT/GNPs/DTX. METHODS: We used HeLa and MDA-MB-231 cells for our study. Cells were incubated with GNPs (0.2nM) in the absence and presence of DTX (50nM) for 24 hrs for determination of uptake, distribution, and retention of NPs. For RT experiment, treated cells were given a 2 Gy dose of 6 MV photons using a linear accelerator. RESULTS: Concurrent treatment of DTX and GNPs resulted in over 85% retention of GNPs in tumor cells. DTX treatment also forced GNPs to be closer to the most important target, the nucleus, resulting in a significant decrease in cell survival with the triple combination of RT, GNPs, and DTX vs. RT plus DTX alone. Our experimental therapeutics results are supported by Monte Carlo simulations. CONCLUSION: The ability to not only trap GNPs at clinically feasible doses but also to retain them within the cells could lead to meaningful fractionated treatments in future combined cancer therapy. Furthermore, the suggested triple combination of RT/GNPs/DTX may allow lowering the RT dose to spare surrounding healthy tissue. ADVANCES IN KNOWLEDGE: This is the first study to show intracellular GNP transport disruption by DTX, and its advantage in radiosensitization. / Graduate / 2020-10-31

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.