Lung cancer is one of the worldwide leading and fast-growing malignancies. Pemetrexed disodium (PEM, Alimta®), a small hydrophilic drug, is currently used for treating lung cancer patients. However, PEM suffers from issues like fast elimination, low bioavailability, poor tumor cell selectivity and penetration. Here, we report on lung cancer specific CSNIDARAC (CC₉) peptide-functionalized reduction-responsive chimaeric polymersomes (CC₉-RCPs) for efficient encapsulation and targeted delivery of PEM to H460 human lung cancer cells in vitro and in vivo. PEM-loaded CC₉-RCPs (PEM-CC₉-RCPs) was obtained from co-self-assembly of poly(ethylene glycol)-b-poly(trimethylene carbonate-co-dithiolane trimethylene carbonate)-b-polyethylenimine (PEG-P(TMC-DTC)-PEI) and CC₉-functionalized PEG-P(TMC-DTC) in the presence of PEM followed by self-crosslinking. PEM-CC₉-RCPs displayed an optimal CC₉ density of 9.0% in targeting H460 cells, a high PEM loading content of 14.2 wt%, a small hydrodynamic size of ca. 60 nm and glutathione-triggered PEM release. MTT assays showed that PEM-CC₉-RCPs was 2.6- and 10- fold more potent to H460 cells than the non-targeting PEM-RCPs and free PEM controls, respectively. Interestingly, PEM-CC₉-RCPs exhibited 22-fold longer circulation time and 9.1-fold higher accumulation in H460 tumor than clinical formulation Alimta®. Moreover, CC₉-RCPs showed obviously better tumor penetration than RCPs. Remarkably, PEM-CC₉-RCPs at 12.5 mg PEM equiv./kg effectively suppressed growth of H460 xenografts and significantly prolonged mouse survival time as compared to PEM-RCPs and Alimta® controls. These lung cancer specific and reduction-responsive chimaeric polymersomes provide a unique pemetrexed nanoformulation for targeted lung cancer therapy.

Statement of Significance

Multitargeted antifolate agent pemetrexed (PEM, Alimta®) is currently used for treating lung cancer patients and has low side-effects. However, PEM suffers from issues like fast elimination, low bioavailability, poor tumor cell selectivity and penetration. Scarce work on targeted delivery of PEM has been reported, partly because most conventional nanocarriers show a low and instable loading for hydrophilic, negatively charged drugs like PEM. Herewith, we report on lung cancer specific CSNIDARAC (CC₉) peptide-functionalized reduction-responsive chimaeric polymersomes (CC₉-RCPs) which showed efficient PEM encapsulation (14.2 wt%, 60 nm) and targeted delivery of PEM to H460 human lung cancer cells, leading to effective suppression of H460 tumor xenografts and significantly prolonged survival rates of mice than Alimta®. To the best of our knowledge, this represents a first report on targeted nanosystems that are capable of efficient loading and targeted delivery of PEM to lung tumors.

中文翻译：

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肺癌特异性和还原反应性嵌合体，可高效装载培美曲塞并靶向抑制体内肺肿瘤

肺癌是世界范围内领先的和快速增长的恶性肿瘤之一。培美曲塞二钠（PEM，Alimta®）是一种小型亲水性药物，目前用于治疗肺癌患者。但是，PEM存在快速消除，生物利用度低，肿瘤细胞选择性和渗透性差的问题。在这里，我们报道了肺癌特异性CSNIDARAC（CC ₉）肽功能化的还原反应性嵌合多聚体（CC ₉ -RCPs），用于在体外和体内将PEM有效地包封和定向递送到H460人肺癌细胞。PEM负载的CC ₉ -RCPs（PEM-CC ₉ -RCPs）是由聚（乙二醇）-b的自组装获得的-聚（碳酸三亚甲基酯-共-二硫代碳酸三亚丙酯）-β-聚乙烯亚胺（PEG-P（TMC-DTC）-PEI）和CC _9-官能化的PEG-P（TMC-DTC），在PEM存在下进行交联。PEM-CC ₉ -RCP在靶向H460细胞中显示出9.0％的最佳CC ₉密度，14.2 wt％的高PEM负载含量，约小的流体动力学尺寸。60 nm和谷胱甘肽触发的PEM释放。MTT分析表明，PEM-CC ₉ -RCP对H460细胞的效力分别是非靶向PEM-RCP和游离PEM对照的2.6倍和10倍。有趣的是，PEM-CC ₉-RCPs在H460肿瘤中的循环时间比临床配方长22倍，在H460肿瘤中的蓄积高9.1倍。此外，CC ₉ -RCPs的肿瘤渗透性明显优于RCPs。值得注意的是，与PEM-RCP和对照组相比，PEM-CC ₉ -RCP的12.5 mg PEM当量/千克有效抑制了H460异种移植物的生长，并显着延长了小鼠的存活时间。这些肺癌特异性和还原反应性的嵌合聚合物囊泡为靶向肺癌治疗提供了独特的培美曲塞纳米制剂。

重要声明

培美曲塞（PEM，Alimta®）多靶点抗叶酸药物目前用于治疗肺癌患者，且副作用低。但是，PEM存在快速消除，生物利用度低，肿瘤细胞选择性和渗透性差的问题。据报道，针对PEM靶向递送的工作很少，部分原因是大多数常规纳米载体对亲水，带负电荷的药物（如PEM）显示出低而不稳定的负载。在此，我们报道了肺癌特异性CSNIDARAC（CC ₉）肽功能化的还原反应性嵌合多聚体（CC ₉-RCPs）表现出有效的PEM封装（14.2 wt％，60 nm）和将PEM靶向递送至H460人肺癌细胞，从而有效抑制H460肿瘤异种移植并比Alimta®显着延长了小鼠的存活率。据我们所知，这是关于靶向纳米系统的第一份报告，该纳米系统能够有效地将PEM加载并靶向递送至肺肿瘤。