一种能够破坏肿瘤药物递送屏障的靶向纳米药物复合物制备与应用及其疗效的PET评估

Breast cancer is one of the most severe diseases with high incidence of malignancy in women, of which the triple negative breast cancer (TNBC) is an aggressive subtype with the worst prognosis and recurrence. Currently, chemotherapy is considered as standard care of cancer management. Unfortunately, most conventional chemotherapy drugs are of low biocompatibility and poor tumor targetability, which always induce severe side effects suffering patients. With the development of nanomedicine, it is now possible to load conventional chemotherapy drug into nanocarrier to improve their in vivo behavior as we demonstrated in our previous publications. The other reason for the unsatisfied chemotherapy treatment response is the existing of the dense tumor stroma in tumor microenvironment. To improve TNBC treatment results, we constructe a tumor integrin targeting peptide, Arg-Gly-Asp (RGD), with matrix metalloproteinase (MMP-2) that can effectively degrade type IV collagen, which rich expressed in tumor stroma, to achieve a targeted stroma breaking recombinant proteinase. This fusion protein was named RGDMMP2. By modification of a hyaluronic acid nanoparticle (HANP)/drug complex, the formed RGDMMP2-HANP/drug nanocomplex will target to the tumor, break down the tumor stroma barrier, increase the chemotherapy drug delivery efficiency and finally improve the TNBC tumor treatment effect. To confirm and evaluate the treatment response, 18F FDG PEG and 18F RGD PET will be used to monitor the tumor metabolic and biomarker changes before and after treatment. Based on our preliminary data, it is promising that our design of project will establish a drug delivery system with improved TNBC treatment effects.

三阴性乳腺癌侵袭性及复发风险高，预后差。目前，化疗是治疗三阴性乳腺癌常用手段之一，但常规化疗药物低生物相容性和弱靶向性所造成的副作用显著制约着其临床应用。此外，肿瘤基质中的致密胶原结构严重阻碍了化疗药物在肿瘤细胞内的聚集，造成化疗效果不理想。为解决以上两个问题，我们构建了一种能够靶向肿瘤组织并能够破坏胶原的新型融合蛋白，RGDMMP2，提出利用RGDMMP2修饰透明质酸纳米颗粒/紫杉醇复合物，以期改善化疗药物的生物相容性性，增加其靶向性，靶向破坏肿瘤部位的胶原屏障，提高肿瘤部位药物富集效率，增强化疗效果。同时本项目将利用18F-FDG和18F-RGD PET对疗效进行监测和临床前评估。本项目最终目的是开发出新型的靶向化疗药物递送系统，提高化疗药物递送效率和治疗效果。

恶性肿瘤严重威胁人类健康和生命。化疗是其主要治疗手段之一。肿瘤微环境药物递送障碍严重降低了化疗药物的肿瘤基质转运及血管转运效率，从而阻碍了其高效渗透到肿瘤细胞，导致药物递送效率低，不能有效杀死肿瘤细胞而引起复发或进展。我们深入研究了肿瘤微环境药物递送障碍，发现除了肿瘤致密的细胞外基质（ECM）中IV型胶原外，ECM中的透明质酸同样会造成肿瘤药物递送效率低，也是解除肿瘤微环境药物递送障碍、提升药物递送效率的研究热点。针对这些药物递送障碍，我们设计制备了相应的能够突破肿瘤内药物递送屏障的纳米药物。针对ECM中的透明质酸屏障，我们设计通过环形RGD肽的修饰提升了纳米载体的肿瘤靶向性，并引入HAase以降解ECM中HA屏障，成功构建了一种新型高效靶向纳米载体，并装载疏水性化疗药物DOX，获得了能够解除肿瘤致密基质屏障的靶向纳米药物c(RGDyK)-HAase-IONP/DOX。通过体外、细胞及动物实验证实了其具有良好的肿瘤靶向性，能够提升肿瘤部位、尤其是远离血管的肿瘤深部的药物递送效果，从而改善了荷瘤小鼠抗肿瘤疗效。同时，我们按照研究计划针对ECM中IV型胶原，首先设计利用具有肿瘤靶向性的ATF肽与能够降解IV型胶原的细胞外基质金属蛋白酶2（MMP-2）融合，完成了ATFmmp融合蛋白的表达、纯化；而后，利用ATFmmp修饰HANP纳米药物，制备出能够破坏肿瘤药物递送屏障的靶向纳米化疗药物，并在不同荷瘤小鼠体内证实了其增强的肿瘤靶向性及药物递送效果。通过NIR830的标记纳米载体并与肿瘤血管标志物CD31的共定位，我们发现ATFmmp-HANP由于靶向性提高及对肿瘤致密基质成分IV 型胶原的降解破坏作用，可在肿瘤组织内递送得更多，更重要的是其可渗透到远离血管的肿瘤深部组织中，从而实现更佳的药物递送效果；并通过化疗药物的装载，在两种荷人源乳腺癌PDX免疫缺陷小鼠肿瘤模型中证实了其增强的抗肿瘤治疗效果及对肿瘤基质胶原成分的降解作用。该研究为肿瘤输送效率低的抗肿瘤药物提供了理想的高效靶向纳米载体和输送平台，为解除肿瘤内药物递送屏障、提高药物肿瘤深部递送效率的新型靶向纳米药物的设计、合成提供了新思路。