Tumor microenvironment responsive VEGF-antibody functionalized pH sensitive liposomes of docetaxel for augmented breast cancer therapy

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 similar to 206 nm with an entrapment efficiency of similar to 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 similar to 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 similar to 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 similar to 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 similar to 2.94-fold increase in t(1/)(2) and a similar to 1.25-fold higher AUC (()(0 ->)(infinity)) as compared to marketed formulation Taxotere (R). Similarly, mean residence time was also increased similar to 2.50-fold as compared to Taxotere (R). Finally, treatment with VEGF-PEG-pH-Lipo-DTX demonstrated significant reduction in % tumor burden (similar to 35%) as compared to Taxotere (R) (similar to 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.

Automated summary

The VEGF antibody functionalized PEGylated pH sensitive liposomes (VEGF-PEG-pH-Lipo-DTX) showed enhanced cellular uptake and cytotoxicity in MCF-7 cell line, as well as anti-angiogenic potential in HUVECs stimulated by VEGF. The pharmacokinetic profile of VEGF-PEG-pH-Lipo-DTX demonstrated improved half-life, AUC, and mean residence time compared to the marketed formulation Taxotere (R), leading to a significant reduction in tumor burden in breast cancer treatment.