抗PD-L1抗体修饰负载BRAF抑制剂的金纳米笼控释系统靶向治疗黑素瘤的研究

Malignant melanoma tend to early metastasis and highly drug-resistant, and has high mortality. Targeted therapy of small molecule inhibitors has rapid onset, but easily get resistant. Immunotherapy has certain effect, however the effect is slow and usually side effects occur. Combination of the two above could decrease the resistant and increase the curative effect, which has became the new treatment for the resistant melanoma abroad. However, the combination treatment is lack of tumor targeting and can not reduce side effects. Multi-functional nano drug delivery system can conquer these disadvantages. Our study intends to design a nano-system in which gold nanocage as a carrier carrying BRAF-inhibitor Vemurafenib, modified with anti-PD-L1 antibody BMS-936559 and aptamer AS1411. BMS-936559 is supposed to target the high expression of PD-L1 on melanoma cells to block PD-1/PD-L1 pathway that enhance killing melanoma cells, and promote tumor cells taking in nanocages via PD-L1-mediated endocytosis. Moreover, AS1411 can act as “molecule switch” to control releasing drugs within tumor cells besides of its tumor-suppression effect. Meanwhile, nanocages has fluorescent effect to tracking distribution of nano-sytstem and photothermal effect to kill tumor cells, hoping to bring some new ideas on the effective treatment for melanoma.

恶性黑素瘤易早期转移且高度耐药，患者死亡率高。小分子抑制剂靶向治疗虽起效迅速，但极易发生耐药。免疫治疗虽疗效确定，但起效慢且易发生副反应。上述药物联合治疗可减少耐药发生，提高疗效，已成国外耐药黑素瘤的新型治疗方案；但其缺乏对肿瘤的特异靶向性，并不能降低毒副作用。多功能纳米载药系统能较好克服以上缺陷。本研究拟以包被BRAF抑制剂Vemurafenib的金纳米笼为载体，偶联PD-L1单克隆抗体BMS-936559，特异性靶向黑素瘤细胞高表达的PD-L1，阻断PD-L1-PD-1信号通路而增强杀伤黑素瘤活性，并通过PD-L1受体介导的内吞作用促进黑素瘤细胞对金笼的摄取，提高胞内药物浓度克服耐药；此外金笼表面修饰的核酸适配体AS1411除具选择性抑瘤效应，作为“分子开关”实现笼内药物在胞内的控制释放。金笼本身的荧光效应可示踪纳米药物的分布，并通过其光热效应杀灭黑素瘤，为黑素瘤治疗提供新的思路。

浅表性皮肤肿瘤（如黑素瘤）发病率高，传统的手术和系统性治疗方式，创伤大且可能引起严重副作用；而外用药物难以透过皮肤角质层屏障，局部治疗的效果受到限制。因此，寻找一种新的高效且微创的替代透皮给药方法，对于浅表性皮肤肿瘤的有效治疗至关重要。因此，本研究设计制备了负载金纳米笼（AuNC）和化疗药物阿霉素（DOX）的透明质酸可溶性微针。负载的金纳米笼不仅增强可溶性微针的机械强度，同时也作为一种有效的光热材料，能实现对浅表性皮肤肿瘤的透皮治疗。研究发现，联合载药微针能有效穿透皮肤角质层屏障，快速溶解、释放负载药物进入皮肤肿瘤处。微针释放的阿霉素和金纳米笼逐渐进入肝脏，并最终在微针给药72小时后基本排出体外。微针中负载的金纳米笼在接受近红外激光照射时，将光能转化为热能，通过光热作用实现对肿瘤细胞的杀伤；同时，微针负载的化疗药物阿霉素在释放入皮损后，能直接对肿瘤细胞进行杀伤。此外，在小鼠皮下黑素瘤体内模型中，验证了载药微针的化疗联合光热治疗的明显抗肿瘤效应，并未发现明显毒副作用。因此，本研究中负载药物/金纳米笼的可溶性微针系统，为治疗浅表性皮肤肿瘤提供了一种有效、安全、微创、联合治疗的新型方式。