Endometrial cancer (EC) is the most common cancer in the female genital tract, and the third leading cancer in European women. Its five-year survival is of a 56% or 20% when locoregional or distal metastasis occur, respectively. Thus, there’s an unmet medical need calling for developing new therapeutic approaches that improve current treatment by achieving a higher inhibition of metastatic dissemination, as well as a significant reduction of its associated systemic toxicity. In collaboration with the Nanobiotechnology group at Universitat Autònoma de Barcelona, our group has developed self-assembling protein nanoparticles, based on T22-GFP-H6 design and structure, to specifically target cells which express chemokine receptor CXCR4 (CXCR4+ cells). This receptor is overexpressed in EC tumor tissue. Immunohistochemical analysis of tumor biopsies from 79 EC patients showed its overexpression in more than 90% of the cases, with predominantly membrane localization. This suggests CXCR4 could be a good therapeutic target in this tumor type, which could be treated using therapeutic nanoparticles targeted to CXCR4+ cells. For the preclinical development of our nanoparticles, we generated new CXCR4+ EC cell lines, which also overexpressed luciferase to allow cell tracking. Among them, we selected the CXCR4+ AN3CA cell line to develop xenograft models of subcutaneous and orthotopic implantation, in Swiss nude or NSG mice, respectively. Our orthotopic models mimicked the clinicopathological features of EC in advanced stages, having a rate of tumor implantation and metastasis development of 100%. Moreover, CXCR4 overexpression showed a large effect on metastatic dissemination. Our nanocarrier, T22-GFP-H6, showed a high and CXCR4-dependent internalization, especially in the AN3CA cell line, without associated cytotoxicity. Moreover, in our subcutaneous model, it was mainly uptaken by CXCR4+ cells in the tumor, reaching its peak after 5 hours from administration. Non-tumor organs showed no histopathological alterations or nanoparticle accumulation. Besides, a screening of multiple nanoparticles carrying different therapeutic agents identified those incorporating bacterial toxins, T22-DITOX-H6 and T22-PE24-H6, as the ones exerting a higher cytotoxic effect in CXCR4+ AN3CA cell line. This effect was CXCR4-dependent and mediated by apoptosis induction, a cell death mechanism that was also confirmed in our subcutaneous model after the intravenous administration of the nanotoxins. In addition, the repeated administration of both nanotoxins in the same model, achieved inhibition of tumor growth, leading to increased mice survival in the absence of side toxicity or nanoparticle accumulation in non-tumor organs. Finally, we used T22-DITOX-H6, which showed the highest antitumor effect, on a repeated dose schedule, to assess its antimetastatic effect on our orthotopic CXCR4+ model. This nanotoxin inhibited the development of peritoneal, lymph node, liver and lung metastasis. Regarding hematogenous metastasis, it dramatically reduced both the number and the area of metastatic foci in liver, as well as the percentage of the area occupied by metastatic cells in the lung. This powerful antitumor effect was exerted at a low dosage, without systemic toxicity. To sum up, our nanoparticle T22-DITOX-H6 shows many advantages over other oncological therapies, including its active targeting to CXCR4+ cells, its nanometric size, and its proteic nature, as well as its unique mechanism of action, inhibiting protein synthesis. All of these nanoparticle properties lead to a high antineoplastic effect in the absence of systemic toxicity. We believe this nanoparticle could represent an excellent therapeutic approach for CXCR4+ EC patients with an advance stage, high risk of progression or recurrent tumors, once after its appropriate preclinical development, since no effective treatments are currently available.
| Date of Award | 18 Oct 2021 |
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| Original language | Spanish |
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| Supervisor | Ramón Mangues Bafalluy (Director) & Raquel Moral Cabrera (Director) |
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