Biodegradable Anti-HER2 Monoclonal Antibody/PCL-PEG/Paclitaxel Worm-like Nanocrystal Micelles For Treatment Of HER2-positive Breast Cancer

Overexpression of HER2 gene in breast cancer is associated with strong tumor aggressiveness and high recurrence rate.Currently,anti-HER2antibody drugs（Herceptin）are combined with chemotherapeutic agents（such as TAXOL^?）to prolong the survival of these patients and improve their quality of life in clinical practice.In view of their drawbacks,this study used Characteristic targeting of the HER2 receptor of Herceptin and the good anti-tumor activity of paclitaxel to construct a Herceptin-conjugated and PTX-loaded,PCL-PEG worm-like nanocrystal micelles for targeted combination therapy of HER2-positive breast cancer.Firstly,we investigated the particle size,distribution,stability and drug loading capacity of PCL-PEG self-assembled micelles with different block ratios,and determined that PCL₂₀₀₀-MPEG₂₀₀₀ and PCL₅₀₀₀-PEG₂₀₀₀-CHO have a mass ratio of 3:7 to package PTX.In the TEM experiment,blank micelles were found to be spheroidal nanoparticles,but they turned into worms after drug-loading（PTX@PCL-PEG）.Then,the primary amines of Herceptin and aldehydes of PCL₅₀₀₀-PEG₂₀₀₀-CHO exposed on the outside surface of the PTX@PCL-PEG micelles were utilized for the first time to form stable,carbon-nitrogen single linkers（–C–N–）between the antibodies and nanoparticles（PTX@PCL-PEG-Herceptin）.Compared with other degradable linkages such as ester bonds,disulfide bonds,amide bonds,etc.,carbon-nitrogen single bonds are not easily degraded,and compared to the thioether bond,it is simple to operate and does not require modification or alteration of the protein.On this basis,we examined various aspects of the preparations in vitro and in vivo.The experimental results showed that the particle size of PTX@PCL-PEG-Herceptin was about 170 nm,and the distribution was uniform.And the results of serum stability test showed that the stability of the micelle within three days was good,the drug loading and encapsulation efficiency were 6.3%and 90%respectively.Besides,the antibody coupling rate was52.6%by the Bradford method.In an in vitro release experiments,the micelles released more slowly than commercially available paclitaxel injections in neutral conditions,while release rates increased remarkably in acidic conditions.At the cellular level,the micelles entered the cell primarily through a caveolin-mediated pathway no matter whether antibodies were attached,but the combination of micelles and HER2-positive breast cancer cells was significantly enhanced because of the attachment of Herceptin and had higher cytotoxicity compared with PTX@PCL-PEG.SD rats and SKBR-3-tumor-xenograft nude mice model were used to evaluate the pharmacokinetics,tissue distribution and antitumor effects in vivo of the preparations.The results showed that PTX@PCL-PEG-Herceptin was easier to enter the tissues from the circulatory system,and more drugs would accumulate in the tumor site.Compared with PTX@PCL-PEG and TAXOL?,it was 2-3 times more effective in inhibiting tumor growth,and greatly reduced the local effect of the drug,which prolongs the survival time of the tumor-bearing BALB/c nude miceIn summary,we have successfully prepared a nanoparticle that can be stabilized in the blood and tumor microenvironment and target HER2-positive breast cancer.This antibody-conjugated nano-preparation has potential value for clinical anti-cancer treatment while is also easy to be industrialized.