Safavy Ahmad, Bonner James A, Waksal Harlan W, Buchsbaum Donald J, Gillespie G Yancey, Khazaeli M B, Arani Ramin, Chen Dung-Tsa, Carpenter Mark, Raisch Kevin P
Department of Radiation Oncology, Biostatistics Unit, University of Alabama at Birmingham, 35294, USA.
Bioconjug Chem. 2003 Mar-Apr;14(2):302-10. doi: 10.1021/bc020033z.
Tumor-targeted drug delivery is an attractive strategy in cancer treatment. We have previously reported a paclitaxel model conjugate using a bombesin receptor-recognizing peptide in which the drug cytotoxicity against H1299 human nonsmall cell lung cancer was enhanced compared to unconjugated taxol. In an effort to expand the development of tumor-recognizing taxanes, paclitaxel (PTX, taxol) was conjugated to the anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibody (MAb) Erbitux (C225) to serve as a model MAb-mediated drug delivery compound. Thus, paclitaxel was derivatized at its 2'-hydroxy function by introduction of a succinate linker, and the carboxyl group of the latter was covalently attached to C225 through amide bond formation. The final product conjugate (PTXC225) was analyzed mass spectrometrically for assessment of the drug-to-antibody ratios. Cytotoxicity screening of the drug-antibody conjugate against A431, UM-SCC-1, and UM-SCC-6 cells indicated an enhancement in cytocidal effect of paclitaxel as compared to those of the free drug, the intact antibody, and a physical mixture of the two (the controls). In A431 cells, the conjugate showed 25.2% +/- 2.2% of apoptosis induction as compared to little or no apoptosis caused by the controls. Biodistribution analysis of the PTXC225 in tumor-implanted nude mice and a tyrosine-kinase assay showed that conjugation of the drug did not interfere with the immunoreactivity of the antibody. The 24-h tumor uptake of C225 and PTXC225 were 11.7% +/- 6.0% and 7.1% +/- 3.6% of the injected dose per gram of tissue (%ID/g), respectively, which were not significantly different. Also, in A431-implanted nude mice, the conjugate and C225 showed tumor growth inhibition effects of 57.2% and 41.2%, respectively, against a saline-treated control, which were not significantly different from each other. This lack of difference in the in vivo antitumor activity of the MAb-delivered drug and free PTX may be due to either a relatively low dose of the antibody-delivered drug (346 microg/kg), or an untimely release of it, or both. The tumor growth inhibition pattern of the conjugate, however, was identical to that of C225, indicating that the attachment of PTX did not affect the antigen-binding and growth inhibitory features of the MAb. These preliminary results demonstrate the potential of tumor-targeted delivery of taxol as a promising strategy in cancer treatment and warrant further work to develop more suitable drug-MAb linkers as well as improved dosage and treatment protocols.
肿瘤靶向给药是癌症治疗中一种有吸引力的策略。我们之前报道过一种使用铃蟾肽受体识别肽的紫杉醇模型偶联物，与未偶联的紫杉醇相比，该偶联物对H1299人非小细胞肺癌的药物细胞毒性有所增强。为了扩大肿瘤识别紫杉烷的开发，将紫杉醇（PTX）与抗表皮生长因子受体（anti-EGFR）单克隆抗体（MAb）爱必妥（C225）偶联，作为一种模型MAb介导的给药化合物。因此，通过引入琥珀酸接头使紫杉醇在其2'-羟基官能团处衍生化，后者的羧基通过酰胺键形成与C225共价连接。对最终产物偶联物（PTXC225）进行质谱分析以评估药物与抗体的比例。对药物 - 抗体偶联物针对A431、UM - SCC - 1和UM - SCC - 6细胞的细胞毒性筛选表明，与游离药物、完整抗体以及两者的物理混合物（对照）相比，紫杉醇的杀细胞作用有所增强。在A431细胞中，与对照引起的很少或无凋亡相比，该偶联物显示出25.2%±2.2%的凋亡诱导率。对PTXC225在荷瘤裸鼠中的生物分布分析以及酪氨酸激酶测定表明，药物的偶联并未干扰抗体的免疫反应性。C225和PTXC225每克组织的24小时肿瘤摄取量分别为注射剂量的11.7%±6.0%和7.1%±3.6%（%ID/g），两者无显著差异。同样，在植入A431的裸鼠中，与盐水处理的对照相比，偶联物和C225的肿瘤生长抑制作用分别为57.2%和41.2%，两者彼此无显著差异。MAb递送的药物与游离PTX在体内抗肿瘤活性方面缺乏差异，可能是由于抗体递送药物的剂量相对较低（346μg/kg），或者其释放不及时，或者两者皆有。然而，偶联物的肿瘤生长抑制模式与C225相同，表明PTX的连接并未影响MAb的抗原结合和生长抑制特性。这些初步结果证明了紫杉醇肿瘤靶向递送作为癌症治疗中一种有前景的策略的潜力，并需要进一步开展工作来开发更合适的药物 - MAb接头以及改进剂量和治疗方案。
