Anticancer Effects Of Long Circulating Doxorubicin-loaded Microemulsions Modified With KDR Antibody

ObjectiveTumor growth and metastasis are closely related to the blood vessels in tumor tissues. New blood vessels around tumor provide nutrition for the rapid growth of tumor and eliminate metabolic waste . It can be said that tumor angiogenesis is material basis of growth and survival of tumors. In view of its important role in the development of tumor, anti-tumor angiogenesis has become an important cancer therapy. VEGF is an important factor to stimulate the growth of blood vessels in tumor. Its receptor-KDR plays an important role in the process of proliferation of vascular endothelial cell and growth of blood vessels. KDR antibody with tumor-blood-targeting ability can strongly antagonize the combition of VEGF and KDR, thereby it can effectively inhibit the growth of tumor. Microemulsion is a new drug delivery system and its main feature is to improve the stabilty of drugs. Microemulsions can also promote drug distribute to certain higher vascular permeability lesion sites (such as tumor) and reduce drug distribute to lower vascular permeability normal tissues (such as the heart). Doxorubicin (DXR) is one of the important anticancer drugs, but it is restricted in clinical application because of its severe adverse reactions, especially cardiac toxicity. The basic purpose of this study is to utilize long-circulating microemulsion technology, tumor -vessel-targeting technology and chemotherapy to prepare long circulating Doxorubicin-loaded microemulsion modified with KDR Antibody(KDR-DXR-M), with a view to increase the efficacy of doxorubicin and reduce its adverse reactions.Research methods and results1. Firstly,we prepared long circulating doxorubicin-loaded microemulsion with polyethylene glycol surfactant, and then connected KDR antibody and long-circulating doxorubicin microemulsion with method of glutaraldehyde, therefore prepared KDR-DXR-M successfully. KDR targeting doxorubicin-loaded microemulsion showed spherical shape, and its diameter was less than 50 nm by frozen etching technology and scanning electron microscopy.2. We segregated KDR-DXR-M by Sephacry1S-400 gel column chromatography, then determined the content (encapsulation efficiency)of doxorubicin in KDR-DXR-M by HPLC method, that is 98.5±0.25% (CV = 0.25%), which demostrated microemulsion doxorubicin was a stable carrier for doxorubicin.3. We determined the content of doxorubicin in mice in vivo at different time, this resuld indicated KDR-DXR-M significantly prolonged the time of doxorubicin in the blood circulation, thereby achieved the purpose of long circulation.4. We determined LD50 of mice by acute toxicity test ,which showed that long-circulating microemulsion and KDR-DXR-M can significantly reduce the acute toxicity of doxorubicin, and there was not significant difference between them.5. We determined the content of doxorubicin in heart at different time, which indicated KDR-DXR-M significantly reduced the distreibution of doxorubicin in heart , thereby remarkably reduced the toxicity of the heart. 6. The results of tumor animal model experiment with S180 mice showed that anti-tumor effects of KDR-DXR-M group was greater than KDR-DXR group, and it was greater than doxorubicin group.The therapeutic efficacy of KDR-DXR-M by small dose multiple administration was better than by large dose simple administration.7. The results of tumor animal model experiment with S180 mice showed that the weight of KDR-DXR-M group was close to that of control group , but the weight of KDR-DXR group was less than that of control group ,and the weight of doxorubicin group was significantly less than that of control group. These results suggested that KDR-DXR-M can significantly reduced the adverse reaction of doxorubicin than DXR .KDR-DXR-M in our study can significantly improved the anti-tumor effects of doxorubicin , meanwhile it can significantly reduce their adverse reactions. Preparation of KDR-DXR-M may lay the theoretical and experimental foundation for the further development of vascular targeting anticancer drug. KDR-DXR-M has a good potential market prospect because of its simple preparation, higher safety, stronger anti-cancer effect.