A Smart CA IX-Targeting and pH-Responsive Nano-Mixed Micelles for Delivery of FB15 with Superior Anti-Breast Cancer Efficacy

XingYun Liu,1,* JingDuo Zhao,2,* FuRong Liu,1 ZhiZhong Xie,2 XiaoYong Lei,2 Zhe Wang,3 Zerui Yang,4 YuSheng Zhou,1,3 GuoTao Tang2 1The Affiliated Nanhua Hospital, Department of Pharmacy, Hengyang Medical School, University of South China, Hengyang, 421001, People’s Republic of China; 2Institute of Pharmacy and Pharmacology, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang, 421001, People’s Republic of China; 3The Second Affiliated Hospital, Department of Pharmacy, Hengyang Medical School, University of South China, Hengyang, 421001, People’s Republic of China; 4NMPA Key Laboratory for Technology Research and Evaluation of Pharmacovigilance, Guangdong Pharmaceutical University, Guangzhou, 510086, People’s Republic of China*These authors contributed equally to this workCorrespondence: YuSheng Zhou, The Affiliated Nanhua Hospital, Hengyang Medical School, University of South China, Hengyang, 421001, People’s Republic of China, Email yszhou08@126.com GuoTao Tang, Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hengyang Medical School, Hengyang, Hunan, 421001, People’s Republic of China, Email tgtzq@163.comBackground: Breast cancer treatment has been a global puzzle, and targeted strategies based on the hypoxic tumor microenvironment (TME) have attracted extensive attention. As a signature transcription factor overexpressed in hypoxia tumor, hypoxia-inducible factor-1 (HIF-1) contribute to cancer progression. Compound 7-(3-(2-chloro-1H-benzo[d]1midazole-1-yl) propoxy)-2-(3,4,5-trime-thoxyphenyl)-4H-chromen-4-one, synthesized and named FB15 in our earlier research, a potential inhibitor of HIF-1α signaling pathway, has been proved a promising drug candidate for many kinds of cancer chemotherapy. However, the poor solubility and undesirable pharmacokinetics of FB15 leads to limited treatment efficacy of tumor, which ultimately restricts its potential clinical applications. Carbonic anhydrase IX (CAIX), a tumor cell transmembrane protein, was overexpressed in hypoxia tumor site. Acetazolamide (AZA), a highly selective ligand targeting CAIX, can be utilized to delivery FB15 to hypoxia tumor site.Methods: In this study, we prepared and characterized FB15 loaded nano-mixed micelles with the AZA conjugated poloxamer 188 (AZA-P188) and D-a-Tocopherol Polyethylene 1000 Glycol Succinate (TPGS), denoted as, AZA-P188/TPGS@FB15. Its delivery efficiency in vitro and in vivo was assessed by in vitro drug release, cytotoxicity assay, cellular uptake, and in vivo pharmacokinetics and fluorescence imaging. Finally, therapeutic effect of AZA-P188/TPGS@FB15 was investigated using a preclinical breast cancer subcutaneous graft model in vivo.Results: In vitro studies revealed that AZA-P188/TPGS@FB15 could efficiently target breast cancer cells mediated by CAIX receptor, trigger FB15 release in response to acidic condition, and enhance cellular uptake and cytotoxicity against breast cancer cells. The pharmacokinetic studies showed that FB15-loaded AZA-functionalized micelles exhibited significantly increased AUC0-t over free FB15. In vivo imaging demonstrated that AZA-functionalized micelles significantly increased the drug distribution in the tumor site. In vivo experiments confirmed that AZA-P188/TPGS@FB15 exhibited superior inhibition of tumor growth in nude mice with good biosafety.Conclusion: AZA-P188/TPGS@FB15 hold promise as a potentially effective therapeutic way for breast cancer. Its targeted delivery system utilizing AZA as a carrier shows potential for improving the efficacy of FB15 in cancer therapy.Keywords: carbonic anhydrase IX-targeting, FB15, hypoxia inducible factor-1, nano-mixed micelles, pH-responsive