逐级pH-响应性纳米载体系统联合免疫疗法和化疗靶向治疗乳腺癌的研究

The combination of immunotherapy and chemotherapy is a novel strategy for clinical cancer therapy and exhibits significant synergistic effects against breast cancer. The results in our preliminary experiments showed that the combination treatment of a formylation peptide agonist — W-peptide and a Toll-like receptor 7/8 agonist — R848 could efficiently recruit and activate immune cells to suppress the growth of tumors. To enhance these antitumor effects of immune cells and further effectively kill tumors, a step pH-responsive nanosystem is designed to be used as carrier for W-peptide, R848 and doxorubicine, thus hoping to realize the targeted therapy on breast cancer by combining immunotherapy and chemotherapy. This nanoparticle system is composed of the hydrophobic core of poly-L-histidine, which has strong pH-responsive property, and the hydrophilic shell of hyaluronic acid, a natural ligand for CD44 that is often over-expressed by the breast cancer cells. W-peptide is chemically bonded to poly-L-histidine, R848 is physically loaded into the nanocores of poly-L-histidine, and doxorubicine is grafted onto the shells of hyaluronic acid via pH-sensitive hydrazone bond. This nanoparticle system can deliver W-peptide, R848 and doxorubicine targeting to the tumor and realize their controlled releases respectively in the tumor microenvironment and tumor cells successively through the enhanced permeability and retention (EPR) effect, the pH-responsive disassembly of the poly-L-histidine nanocores in the tumor microenvironment (pH6.5～7.0), the specific affinity of hyaluronic acid for CD44, and the breakage of hydrazone bond in endosomes/lysosomes (pH≈5.5). Thus, these three anticancer drugs can efficiently exert their therapeutic effects respectively aiming to the immune cells and breast cancer cells.

免疫疗法与化疗联合对乳腺癌的治疗具有协同增效作用。前期研究发现甲酰肽受体激动剂W-peptide与Toll样受体7/8激动剂R848联用，能招募并激活免疫细胞作用于肿瘤。为了增强这种免疫作用并有效杀伤肿瘤，本项目拟构建一种逐级pH-响应性纳米载体，用于携载W-peptide、R848与阿霉素，以联合免疫疗法与化疗靶向治疗乳腺癌。纳米载体由聚组氨酸疏水核与透明质酸亲水外壳组成。W-peptide化学键合于聚组氨酸；R848物理包埋于纳米核；阿霉素通过pH-敏感性腙键桥连于透明质酸外壳。纳米药物共载体系可先后通过EPR效应，聚组氨酸对肿瘤微环境的pH-响应性（pH6.5～7.0），透明质酸对乳癌细胞表面CD44的特异亲和性，以及腙键在内吞体/溶酶体中的pH-敏感性（pH≈5.5），实现药物靶向投递以及三种药物在肿瘤微环境与肿瘤细胞内的可控释放，从而高效发挥分别针对免疫细胞与乳癌细胞的协同作用。

乳腺癌是严重威胁女性生命健康的恶性肿瘤之一。在中国，乳腺癌发病率近年来呈显著增加的趋势，已居女性癌症发病的首位。目前乳腺癌的临床治疗方法包括手术治疗、放疗、化疗、内分泌治疗和生物免疫治疗等。虽然现代医疗技术的提高及早期诊断的发展使得乳腺癌的治愈率有了大幅度的提高，但仍然避免不了30%左右的患者会出现转移和复发。因此，越来越多的研究发现多种药物联合例如免疫治疗和传统治疗方法的联合使用更具优势。基于以上本项目设计并构建了多种联合治疗纳米载体系统用于乳腺癌的联合治疗，主要包括三部分：一、逐级pH-响应型纳米载体系统联合免疫疗法与化疗对乳腺癌的协同作用研究；二、基于高分子铜络合剂的纳米载药体系的构建及其联合抗血管生成抑制与免疫疗法靶向治疗乳腺癌的研究；三、pH与氧化还原双重响应的聚氨基酯纳米共载体系联合化疗与COX-2抑制剂逆转乳腺癌耐药的研究。项目系统阐明了纳米载体系统对多种药物的高效共载、靶向递送、时序释放及其对乳腺癌的协同作用，并从体内外全面地阐述了其作用机制，项目的研究数据为临床乳腺癌综合治疗提供一定理论依据与数据支持。