Department of Chemistry, Section of Organic Chemistry and Biochemistry, Laboratory of Chemical Biology, University of Ioannina, Ioannina, GR-45110, Greece.
Division of Pharmacology-Pharmacotechnology, Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
Eur J Med Chem. 2019 Mar 15;166:256-266. doi: 10.1016/j.ejmech.2019.01.041. Epub 2019 Jan 18.
Peptide-drug conjugates have emerged as a potent approach to enhance the targeting and pharmacokinetic profiles of drugs. However, the impact of the linker unit has not been explored/exploited in depth. Gemcitabine (dFdC) is an anticancer agent used against a variety of solid tumours. Despite its potency, gemcitabine suffers mostly due to its unspecific toxicity, lack of targeting and rapid metabolic inactivation. To minimize these limitations and enable its targeting to tumours overexpressing the GnRH receptor, we examined the peptide-drug conjugation approach. Our design hypothesis was driven by the impact that the linker unit could have on the peptide-drug conjugate efficacy. Along these lines, in order to exploit the potential to manipulate the potency of gemcitabine through altering the linker unit we constructed three different novel peptide-drug conjugates assembled of gemcitabine, the tumour-homing peptide D-Lys-GnRH and modified linker building blocks. Specifically, the linker was sculpted to either allow slow drug release (utilizing carbamate bond) or rapid disassociation (using amide and ester bonds). Notably, the new analogues possessed up to 95.5-fold enhanced binding affinity for the GnRH receptor (GnRH-R) compared to the natural peptide ligand D-Lys-GnRH. Additionally, their in vitro cytotoxicity was evaluated in four different cancer cell lines. Their cellular uptake, release of gemcitabine and inactivation of gemcitabine to its inactive metabolite (dFdU) was explored in a representative cell line. In vitro stability and the consequent drug release were evaluated in cell culture medium and human plasma. In vivo pharmacokinetic studies were performed in mice, summarizing the relative stability of the three conjugates and the released levels of gemcitabine in comparison with dFdU. These studies suggest that the fine tuning of the linkage within a peptide-drug conjugate affects the drug release rate and its overall pharmaceutical profile. This could eventually emerge as an intriguing medicinal chemistry approach to optimize bio-profiles of prodrugs.
肽药物偶联物已成为增强药物靶向性和药代动力学特征的有效方法。然而，连接子单元的影响尚未得到深入探索/利用。吉西他滨（dFdC）是一种用于多种实体瘤的抗癌药物。尽管具有很强的功效，但吉西他滨主要由于其非特异性毒性、缺乏靶向性和快速代谢失活而受到限制。为了最大限度地减少这些限制并使其能够靶向过度表达 GnRH 受体的肿瘤，我们研究了肽药物偶联物的方法。我们的设计假设受到连接子单元对肽药物偶联物功效的影响。沿着这些思路，为了通过改变连接子单元来利用操纵吉西他滨效力的潜力，我们构建了三种不同的新型肽药物偶联物，由吉西他滨、肿瘤归巢肽 D-Lys-GnRH 和修饰的连接子构建块组成。具体而言，连接子被塑造为允许缓慢释放药物（利用碳酸酯键）或快速解离（使用酰胺和酯键）。值得注意的是，与天然肽配体 D-Lys-GnRH 相比，新类似物对 GnRH 受体（GnRH-R）的结合亲和力提高了高达 95.5 倍。此外，还在四种不同的癌细胞系中评估了它们的体外细胞毒性。在代表性细胞系中研究了它们的细胞摄取、吉西他滨的释放以及吉西他滨失活为其无活性代谢物（dFdU）的情况。在细胞培养基和人血浆中评估了体外稳定性和随后的药物释放。在小鼠中进行了体内药代动力学研究，总结了三种偶联物的相对稳定性以及与 dFdU 相比吉西他滨的释放水平。这些研究表明，肽药物偶联物中连接的精细调整会影响药物释放速度及其整体药物特性。这最终可能成为优化前药生物特性的一种有趣的药物化学方法。
