Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy , University of Toronto , Toronto M5S 3M2 , Canada.
Mol Pharm. 2018 Sep 4;15(9):3672-3681. doi: 10.1021/acs.molpharmaceut.8b00217. Epub 2018 Jun 14.
Clinical studies examining the combination of paclitaxel (PTX) and everolimus (EVER), an mTOR inhibitor, have failed to result in significant improvements in efficacy and toxicity in patients with breast cancer (BC), relative to treatment with PTX alone. These disappointing clinical trial results have been attributed to poorly designed preclinical studies using the combination of PTX and EVER as well as the significantly different pharmacokinetic profiles of the two drugs. In the current work, the potential synergy between PTX and EVER was examined in a panel of six BC cell lines that differ in terms of their molecular subtype and drug sensitivity. Polymeric nanoparticles (NPs) were used to encapsulate PTX and EVER at an optimal synergistic ratio to achieve specific, colocalized delivery of the combination therapy in BC cell lines. Combinations of PTX and EVER (especially at relatively high doses of EVER) resulted in pronounced synergy in all BC cell lines evaluated. The optimal molar ratio of PTX:EVER was determined to be 1:0.5. The combination was delivered to BC cells at the synergistic ratio via encapsulation within polymeric NPs formed from the poly(ethylene glycol)- b-poly(lactide- co-glycolide) (PEG- b-PLGA) copolymer. The NPs had an average diameter of less than 100 nm and were capable of in vitro retention of the encapsulated PTX and EVER at the optimal synergistic molar ratio for over 7 days. Cytotoxicity data demonstrated that PTX+EVER-loaded NPs were significantly less cytotoxic than the free drug combination in MCF-7 and SKBR3 BC cell lines following 72 h, suggesting that PTX+EVER-loaded NPs remain stable and retain the drug combination loaded within the core after 72 h. The uptake of FITC-labeled NPs in SKBR3 cells was evaluated by flow cytometry, with approximately 41% of cells demonstrating detectable fluorescence after 24 h of exposure. The thorough and systematic approach used in this study to determine and evaluate a synergistic PTX:EVER ratio in conjunction with a potentially promising delivery vector for the drug combination could offer a future clinical benefit for patients with BC.
临床研究表明，紫杉醇（PTX）和 everolimus（EVER）联合使用，一种 mTOR 抑制剂，在乳腺癌（BC）患者中并未导致疗效和毒性的显著改善，与单独使用 PTX 相比。这些令人失望的临床试验结果归因于使用 PTX 和 EVER 联合进行的设计不佳的临床前研究，以及两种药物的药代动力学特征显著不同。在目前的工作中，在一组不同分子亚型和药物敏感性的 6 种 BC 细胞系中研究了 PTX 和 EVER 之间的潜在协同作用。聚合物纳米粒子（NPs）用于封装 PTX 和 EVER，以达到最佳协同比，实现组合疗法在 BC 细胞系中的特异性、共定位递送。在所有评估的 BC 细胞系中，PTX 和 EVER 的组合（尤其是在 EVER 的相对高剂量下）导致明显的协同作用。确定 PTX:EVER 的最佳摩尔比为 1:0.5。通过将其封装在由聚（乙二醇）-b-聚（乳酸-共-乙醇酸）（PEG- b-PLGA）共聚物形成的聚合物 NPs 中，将组合以协同比递送到 BC 细胞。NP 的平均直径小于 100nm，并能够在体外以最佳协同摩尔比保留封装的 PTX 和 EVER 超过 7 天。细胞毒性数据表明，在 MCF-7 和 SKBR3 BC 细胞系中，与游离药物组合相比，PTX+EVER 负载 NP 在 72 小时后明显毒性较小，这表明 PTX+EVER 负载 NP 在 72 小时后保持稳定并保留核心内负载的药物组合。通过流式细胞术评估 SKBR3 细胞中 FITC 标记的 NPs 的摄取，暴露 24 小时后约有 41%的细胞显示出可检测的荧光。本研究采用全面系统的方法确定和评估协同性 PTX:EVER 比值，并与药物组合的潜在有前途的递送载体相结合，可为 BC 患者带来未来的临床益处。
