Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235.
Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232.
Proc Natl Acad Sci U S A. 2017 Aug 8;114(32):E6490-E6497. doi: 10.1073/pnas.1621240114. Epub 2017 Jul 24.
Clinical translation of therapies based on small interfering RNA (siRNA) is hampered by siRNA's comprehensively poor pharmacokinetic properties, which necessitate molecule modifications and complex delivery strategies. We sought an alternative approach to commonly used nanoparticle carriers by leveraging the long-lived endogenous serum protein albumin as an siRNA carrier. We synthesized siRNA conjugated to a diacyl lipid moiety (siRNA-L), which rapidly binds albumin in situ. siRNA-L, in comparison with unmodified siRNA, exhibited a 5.7-fold increase in circulation half-life, an 8.6-fold increase in bioavailability, and reduced renal accumulation. Benchmarked against leading commercial siRNA nanocarrier in vivo jetPEI, siRNA-L achieved 19-fold greater tumor accumulation and 46-fold increase in per-tumor-cell uptake in a mouse orthotopic model of human triple-negative breast cancer. siRNA-L penetrated tumor tissue rapidly and homogeneously; 30 min after i.v. injection, siRNA-L achieved uptake in 99% of tumor cells, compared with 60% for jetPEI. Remarkably, siRNA-L achieved a tumor:liver accumulation ratio >40:1 vs. <3:1 for jetPEI. The improved pharmacokinetic properties of siRNA-L facilitated significant tumor gene silencing for 7 d after two i.v. doses. Proof-of-concept was extended to a patient-derived xenograft model, in which jetPEI tumor accumulation was reduced fourfold relative to the same formulation in the orthotopic model. The siRNA-L tumor accumulation diminished only twofold, suggesting that the superior tumor distribution of the conjugate over nanoparticles will be accentuated in clinical situations. These data reveal the immense promise of in situ albumin targeting for development of translational, carrier-free RNAi-based cancer therapies.
基于小干扰 RNA（siRNA）的疗法的临床转化受到 siRNA 综合较差的药代动力学特性的阻碍，这需要对分子进行修饰和采用复杂的递药策略。我们寻求一种替代常用纳米颗粒载体的方法，利用长寿命的内源性血清蛋白白蛋白作为 siRNA 载体。我们合成了与二酰基脂质部分缀合的 siRNA（siRNA-L），其可在体内原位快速结合白蛋白。与未修饰的 siRNA 相比，siRNA-L 的循环半衰期延长了 5.7 倍，生物利用度增加了 8.6 倍，肾脏蓄积减少。与体内喷射 PEI 等领先的商业 siRNA 纳米载体相比，siRNA-L 在人三阴性乳腺癌的原位模型中实现了 19 倍的肿瘤蓄积和 46 倍的每个肿瘤细胞摄取增加。siRNA-L 快速且均匀地渗透到肿瘤组织中；静脉注射后 30 分钟，siRNA-L 达到 99%的肿瘤细胞摄取，而喷射 PEI 为 60%。值得注意的是，siRNA-L 的肿瘤：肝脏蓄积比>40:1，而喷射 PEI 为<3:1。siRNA-L 的改善的药代动力学特性促进了两次静脉注射后 7 天的显著肿瘤基因沉默。这一概念验证扩展到了一个患者来源的异种移植模型，其中与原位模型中的相同制剂相比，喷射 PEI 的肿瘤蓄积减少了四倍。siRNA-L 的肿瘤蓄积仅减少了两倍，这表明在临床情况下，缀合物相对于纳米颗粒的优越肿瘤分布将更加明显。这些数据揭示了利用白蛋白原位靶向进行转化、无载体 RNAi 癌症治疗开发的巨大潜力。
