The present work exploits the tumor microenvironment which differs significantly from normal cellular environment in terms of both, having lower extracellular pH and increased angiogenesis capacity. To reduce systemic toxicity of docetaxel (DTX) and increase its therapeutic potential, VEGF antibody functionalized PEGylated pH sensitive liposomes (VEGF-PEG-pH-Lipo-DTX) were developed. The liposomes prepared by thin film hydration technique were later conjugated with VEGF antibody on liposomal surface by standard carbodiimide chemistry and using DSPE-PEG-COOH as linker. The VEGF-PEG-pH-Lipo-DTX displayed particle size of ~206 nm with an entrapment efficiency of ~62%. The transmission electron microscopy images revealed spherical shape of liposomes and corroborated the particle size obtained from zetasizer. The in vitro release study revealed biphasic release pattern of DTX from VEGF-PEG-pH-Lipo-DTX. The % drug released was also significantly higher at pH 5.5 which guarantees rapid endosomal escape and faster intracellular drug release. In case of VEGF-PEG-pH-Lipo-DTX the cellular uptake in MCF-7 cell line was augmented ~3.17-fold as compared to free DTX probably due to the VEGF-positive nature of MCF-7 cell (increased affinity for VEGF). Further, it was evident from the cytotoxicity assay that VEGF-PEG-pH-Lipo-DTX showed higher cytotoxicity in MCF-7 cells and ~5.78-fold reduction in IC₅₀ value as compared to free DTX. The apoptotic index observed in case of VEGF-PEG-pH-Lipo-DTX was ~1.70-fold higher than free DTX. The VEGF-PEG-pH-Lipo-DTX inhibited the proliferation of HUVECs stimulated by VEGF, warranting its anti-angiogenic potential. Furthermore, pharmacokinetic profile of VEGF-PEG-pH-Lipo-DTX revealed a ~2.94-fold increase in t_1/2 and a ~1.25-fold higher AUC _(0→∞) as compared to marketed formulation Taxotere®. Similarly, mean residence time was also increased ~2.50-fold as compared to Taxotere®. Finally, treatment with VEGF-PEG-pH-Lipo-DTX demonstrated significant reduction in % tumor burden (~35%) as compared to Taxotere® (~75%). Thus, the combined approach of using PEGylated pH sensitive liposomes along with VEGF antibody functionalization for efficient targeting can improve current standards of DTX therapy for treatment of breast cancer.

目前的工作是利用肿瘤微环境，该环境与正常细胞环境有明显的区别，两者具有较低的细胞外pH和增加的血管生成能力。为了降低多西紫杉醇（DTX）的全身毒性并增加其治疗潜力，开发了VEGF抗体功能化的PEG化pH敏感脂质体（VEGF-PEG-pH-Lipo-DTX）。随后通过标准碳二亚胺化学反应并使用DSPE-PEG-COOH作为接头，将通过薄膜水化技术制备的脂质体与VEGF抗体在脂质体表面偶联。VEGF-PEG-pH-Lipo-DTX显示〜206 nm的粒径，包封率为〜62％。透射电子显微镜图像显示脂质体为球形，并证实了从ZETASizer获得的粒径。在体外释放研究揭示了DTX从VEGF-PEG-pH-Lipo-DTX的双相释放模式。在pH 5.5时，药物释放的百分比也显着更高，从而保证了快速的内体逸出和细胞内药物的快速释放。在VEGF-PEG-pH-Lipo-DTX的情况下，与游离DTX相比，MCF-7细胞系的细胞摄取增加了〜3.17倍，这可能是由于MCF-7细胞的VEGF阳性（增加了对VEGF的亲和力） ）。此外，从细胞毒性试验中可以明显看出，VEGF-PEG-pH-Lipo-DTX在MCF-7细胞中显示出更高的细胞毒性，在IC _50中降低约5.78倍与免费DTX相比的价值。在VEGF-PEG-pH-Lipo-DTX的情况下观察到的细胞凋亡指数比游离DTX高约1.70倍。VEGF-PEG-pH-Lipo-DTX抑制了VEGF刺激的HUVEC的增殖，从而具有抗血管生成的潜力。此外，VEGF-PEG-pH-Lipo-DTX的药代动力学特征显示t _1/2升高约2.94倍，AUC升高约1.25倍_{（0→∞）}与市售配方Taxotere®相比。同样，与Taxotere®相比，平均停留时间也增加了约2.50倍。最后，与（约75％）相比，用VEGF-PEG-pH-Lipo-DTX治疗可显着降低肿瘤负荷百分比（〜35％）。因此，将PEG化pH敏感脂质体与VEGF抗体功能化一起用于有效靶向的组合方法可以改善用于治疗乳腺癌的DTX疗法的当前标准。