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The growing research interest in nanomedicine for the treatment of cancer and inflammatory-related pathologies is yielding encouraging results. Unfortunately, enthusiasm is tempered by the limited specificity of the enhanced permeability and retention effect. Factors such as lack of cellular specificity, low vascular density, and early release of active agents prior to reaching their target contribute to the limitations of the enhanced permeability and retention effect. However, improved nanomedicine designs are creating opportunities to overcome these problems. In this review, we present examples of the advances made in this field and endeavor to highlight the potential of these emerging technologies to improve targeting of nanomedicine to specific pathological cells and tissues.

The current study demonstrates the efficiency of SMA for drug delivery, the influence of physicochemical characteristics on cytotoxicity, and provides the basis for preclinical testing in vivo.

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor. Despite the advances in surgery, radiotherapy and chemotherapy, patient survival averages only 14.6 months. In most GBM tumors, tyrosine kinases show increased activity and/or expression and actively contribute to the development, recurrence and onset of treatment resistance; making their inhibition an appealing therapeutic strategy. We compared the cytotoxicity of 12 tyrosine kinase inhibitors in vitro. A combination of crizotinib and dasatinib emerged as the most cytotoxic across established and primary human GBM cell lines. The combination treatment induced apoptotic cell death and polyploidy. Furthermore, the combination treatment led to the altered expression and localization of several tyrosine kinase receptors such as Met and EGFR and downstream effectors as such as SRC. Furthermore, the combination treatment reduced the migration and invasion of GBM cells and prevented endothelial cell tube formation in vitro. Overall, our study demonstrated the broad specificity of a combination of crizotinib and dasatinib across multiple GBM cell lines. These findings provide insight into the development of alternative therapy for the treatment of GBM.

ALK positive non-small cell lung cancer is highly responsive to ALK inhibitors such as crizotinib, but drug resistance typically develops within a year of treatment. In this study we investigated whether IGF-1R is an independent druggable target in ALK-positive lung cancer cells. We confirmed that combination ALK and IGF-1R inhibitor treatment is synergistically cytotoxic to ALK-positive lung cancer cells and that this remains the case for at least 12 days after initial exposure to crizotinib. ALK-positive cells with acquired resistance to crizotinib did not acquire cross-resistance to IGF-1R inhibition, though combination treatment in the resistant cells gave additive rather than synergistic cytotoxicity. We concluded that IGF-1R is an independent druggable target in ALK-positive lung cancer and support the trial of combination treatment.

Glioblastoma multiforme (GBM) defies the currently practiced management of radiotherapy, chemotherapy and surgery and hence, it is associated with a high fatality rate with a median survival of 14.6 months. In our previous work investigating different tyrosine kinase inhibitors (TKIs), we established that a combination of Crizotinib and Dasatinib exerted the most potent effect on different GBM cell lines. In this work, to improve targeted therapy at the site of the tumour and avoid systemic toxicity, we exploited the enhanced permeability and retention effect by designing micellar formulations of these two TKIs. Crizotinib and Dasatinib were successfully encapsulated in poly(styrene-co-maleic acid) (SMA) micelles which were then evaluated for their physicochemical characteristics, anti-proliferative effect, mode of cell death, efficacy in spheroid models, effect on cell signalling, antiangiogenic potential and in vivo anticancer activity. Our results showed that this combination had induced a potent anti-proliferative effect in four GBM cell lines grown as a monolayer and as a spheroid. The combination was also efficacious in in vitro models of angiogenesis and vascular mimicry. In vivo data showed the enhanced activity of the micellar TKIs compared to free drugs. In conclusion, we proved that micellar formulations of Crizotinib and Dasatinib carry promising in vitro and in vivo efficacy that warrant further investigation.

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Of patients with castrate resistant prostate cancer (CRPC), less than 25–33% survive more than five years. Recent studies have implicated estrogen, acting either alone or synergistically with androgens in the development of castrate resistant prostate cancer. Several in vitro and in vivo studies, as well as a limited number of clinical trials, have highlighted the potential of selective estrogen receptor modulators, such as raloxifene (Ral) for the treatment of castrate resistant prostate cancer. However, the poor oral bioavailability and metabolism of selective estrogen receptor modulators limit their efficiency in clinical application. To overcome these limitations, we have used styrene co-maleic acid (SMA) micelle to encapsulate raloxifene. Compared to free drug, SMA-Ral micelles had 132 and 140% higher cytotoxicity against PC3 and DU 145 prostate cell lines, respectively. SMA-Ral effectively inhibits cell cycle progression, increases apoptosis, and alters the integrity of tumor spheroid models. In addition, the micellar system induced changes in expression and localization of estrogen receptors, epidermal growth factor receptor (EGFR), and downstream effectors associated with cell proliferation and survival. Finally, SMA-Ral treatment decreased migration and invasion of castrate resistant prostate cancer cell lines. In conclusion, SMA-Ral micelles can potentially benefit new strategies for clinical management of castrate resistant prostate cancer.