Tumor-Targeting Micelles Based on Linear–Dendritic PEG–PTX8 Conjugate for Triple Negative Breast Cancer Therapy

Most small molecular chemotherapeutics have poor water solubility and unexpected pharmacokinetics and toxicity to normal tissues. A series of nano drug delivery systems have been developed to solve the problems, among which a micelle based on linear–dendritic polymer–drug conjugates (LDPDCs) is a promising strategy to deliver hydrophobic chemotherapeutics due to its small size, fine stability in blood circulation, and high drug loading capacity. In this work we synthesized a novel amphiphilic linear–dendritic PEG–PTX8 conjugate which can also encapsulate extra free PTX and self-assemble into uniform ultrasmall micelles with a hydrated diameter of 25.50 ± 0.27 nm. To realize efficient drug delivery to tumor sites, a cyclic tumor homing and penetrating peptide iNGR was linked to the PEG–PTX8 conjugate. The biological evaluation was performed on a human triple negative breast cancer model. PTX accumulation in tumor at 24 h of the TNBC-bearing mice treated with iNGR–PEG–PTX8/PTX micelles was significantly enhanced (P < 0.001, two-way ANOVA) compared to that of Taxol and untargeted MeO–PEG–PTX8/PTX micelles. Furthermore, iNGR–PEG–PTX8/PTX micelles showed an obvious strong antitumor effect, and the median survival time of TNBC bearing mice treated with iNGR-modified micelles was significantly extended compared to Taxol. Therefore, this smart micelle system may be a favorable platform for effective TNBC therapy.