Leamon Christopher P, Vlahov Iontcho R, Reddy Joseph A, Vetzel Marilynn, Santhapuram Hari Krishna R, You Fei, Bloomfield Alicia, Dorton Ryan, Nelson Melissa, Kleindl Paul, Vaughn Jeremy F, Westrick Elaine
Endocyte, Inc. , 300 Kent Avenue, West Lafayette, Indiana 47906, United States.
Bioconjug Chem. 2014 Mar 19;25(3):560-8. doi: 10.1021/bc400441s. Epub 2014 Mar 11.
Vintafolide is a potent folate-targeted vinca alkaloid small molecule drug conjugate (SMDC) that has shown promising results in multiple clinical oncology studies. Structurally, vintafolide consists of 4 essential modules: (1) folic acid, (2) a hydrophilic peptide spacer, (3) a disulfide-containing, self-immolative linker, and (4) the cytotoxic drug, desacetylvinblastine hydrazide (DAVLBH). Here, we report a structure-activity study evaluating the biological impact of (i) substituting DAVLBH within the vintafolide molecule with other vinca alkaloid analogues such as vincristine, vindesine, vinflunine, or vinorelbine; (ii) substituting the naturally (S)-configured Asp-Arg-Asp-Asp-Cys peptide with alternative hydrophilic spacers of varied composition; and (iii) varying the composition of the linker module. A series of vinca alkaloid-containing SMDCs were synthesized and purified by HPLC and LCMS. The SMDCs were screened in vitro against folate receptor (FR)-positive cells, and anti-tumor activity was tested against well-established subcutaneous FR-positive tumor xenografts. The cytotoxic and anti-tumor activity was directly compared to that produced by vintafolide. Among all the folate vinca alkaloid SMDCs tested, DAVLBH-containing SMDCs were active, while those constructed with vincristine, vindesine, or vinorelbine analogues failed to produce meaningful biological activity. Within the DAVLBH series, having a bioreleasable, self-immolative linker system was found to be critical for activity since multiple analogues constructed with thioether-based linkers all failed to produce meaningful activity both in vitro and in vivo. Substitutions of some or all of the natural amino acids within vintafolide's hydrophilic spacer module did not significantly change the in vitro or in vivo potency of the SMDCs. Vintafolide remains one of the most potent folate-vinca alkaloid SMDCs produced to date, and continued clinical development is warranted.
维替泊芬是一种强效的叶酸靶向长春花生物碱小分子药物偶联物（SMDC），已在多项临床肿瘤学研究中显示出有前景的结果。在结构上，维替泊芬由4个基本模块组成：（1）叶酸，（2）亲水性肽间隔区，（3）含二硫键的自毁连接子，以及（4）细胞毒性药物去乙酰长春碱酰肼（DAVLBH）。在此，我们报告一项构效关系研究，评估（i）用长春新碱、长春地辛、长春氟宁或长春瑞滨等其他长春花生物碱类似物替代维替泊芬分子中的DAVLBH的生物学影响；（ii）用组成不同的替代亲水性间隔区替代天然（S）构型的天冬氨酸-精氨酸-天冬氨酸-天冬氨酸-半胱氨酸肽；以及（iii）改变连接子模块的组成。通过高效液相色谱法（HPLC）和液相色谱-质谱联用（LCMS）合成并纯化了一系列含长春花生物碱的SMDC。在体外针对叶酸受体（FR）阳性细胞对这些SMDC进行筛选，并针对已建立的皮下FR阳性肿瘤异种移植模型测试抗肿瘤活性。将细胞毒性和抗肿瘤活性与维替泊芬产生的活性直接进行比较。在所有测试的叶酸长春花生物碱SMDC中，含DAVLBH的SMDC具有活性，而用长春新碱、长春地辛或长春瑞滨类似物构建的SMDC未能产生有意义的生物学活性。在DAVLBH系列中，发现具有可生物释放的自毁连接子系统对活性至关重要，因为用硫醚基连接子构建的多个类似物在体外和体内均未能产生有意义的活性。在维替泊芬的亲水性间隔区模块中部分或全部天然氨基酸的替代并未显著改变SMDC的体外或体内效力。维替泊芬仍然是迄今为止产生的最有效的叶酸-长春花生物碱SMDC之一，值得继续进行临床开发。
