Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, The State University of New York at Buffalo, Buffalo, New York.
Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, The State University of New York at Buffalo, Buffalo, New York
Drug Metab Dispos. 2020 May;48(5):368-377. doi: 10.1124/dmd.119.089276. Epub 2020 Feb 21.
Antibody-drug conjugates (ADCs) employ overexpressed cell surface antigens to deliver cytotoxic payloads inside cancer cells. However, the relationship between target expression and ADC efficacy remains ambiguous. In this manuscript, we have addressed a part of this ambiguity by quantitatively investigating the effect of antigen expression levels on ADC exposure within cancer cells. Trastuzumab-valine-citrulline-monomethyl auristatin E was used as a model ADC, and four different cell lines with diverse levels of human epidermal growth factor receptor 2 (HER2) expression were used as model cells. The pharmacokinetics (PK) of total trastuzumab, released monomethyl auristatin E (MMAE), and total MMAE were measured inside the cells and in the cell culture media following incubation with two different concentrations of ADC. In addition, target expression levels, target internalization rate, and cathepsin B and MDR1 protein concentrations were determined for each cell line. All the PK data were mathematically characterized using a cell-level systems PK model for ADC. It was found that SKBR-3, MDA-MB-453, MCF-7, and MDA-MB-468 cells had ∼800,000, ∼250,000, ∼50,000, and ∼10,000 HER2 receptors per cell, respectively. A strong linear relationship ( > 0.9) was observed between HER2 receptor count and released MMAE exposure inside the cancer cells. There was an inverse relationship found between HER2 expression level and internalization rate, and cathepsin B and multidrug resistance protein 1 (MDR1) expression level varied slightly among the cell lines. The PK model was able to simultaneously capture all the PK profiles reasonably well while estimating only two parameters. Our results demonstrate a strong quantitative relationship between antigen expression level and intracellular exposure of ADCs in cancer cells. SIGNIFICANCE STATEMENT: In this manuscript, we have demonstrated a strong linear relationship between target expression level and antibody-drug conjugate (ADC) exposure inside cancer cells. We have also shown that this relationship can be accurately captured using the cell-level systems pharmacokinetics model developed for ADCs. Our results indirectly suggest that the lack of relationship between target expression and efficacy of ADC may stem from differences in the pharmacodynamic properties of cancer cells.
抗体药物偶联物（ADCs）利用过度表达的细胞表面抗原将细胞毒性有效载荷递送到癌细胞内。然而，靶标表达与 ADC 疗效之间的关系仍然不明确。在本手稿中，我们通过定量研究抗原表达水平对癌细胞内 ADC 暴露的影响，部分解决了这种不确定性。曲妥珠单抗-缬氨酸-瓜氨酸-单甲基澳瑞他汀 E 被用作模型 ADC，四种不同的细胞系具有不同水平的人表皮生长因子受体 2（HER2）表达，被用作模型细胞。在孵育两种不同浓度的 ADC 后，在细胞内和细胞培养物培养基中测量了总曲妥珠单抗、释放的单甲基澳瑞他汀 E（MMAE）和总 MMAE 的药代动力学（PK）。此外，还确定了每个细胞系的靶标表达水平、靶标内化率以及组织蛋白酶 B 和 MDR1 蛋白浓度。使用针对 ADC 的细胞水平系统 PK 模型对所有 PK 数据进行了数学描述。结果发现，SKBR-3、MDA-MB-453、MCF-7 和 MDA-MB-468 细胞的每个细胞分别有约 800,000、250,000、50,000 和 10,000 个 HER2 受体。观察到 HER2 受体计数与癌细胞内释放的 MMAE 暴露之间存在很强的线性关系（ > 0.9）。发现 HER2 表达水平与内化率之间存在反比关系，而组织蛋白酶 B 和多药耐药蛋白 1（MDR1）表达水平在细胞系之间略有差异。PK 模型能够在仅估计两个参数的情况下很好地同时捕捉所有 PK 谱。我们的结果表明，抗原表达水平与癌细胞内 ADC 的细胞内暴露之间存在很强的定量关系。
在本手稿中，我们证明了靶标表达水平与癌细胞内 ADC 暴露之间存在很强的线性关系。我们还表明，使用针对 ADC 开发的细胞水平系统药代动力学模型可以准确地捕捉到这种关系。我们的结果间接表明，靶标表达与 ADC 疗效之间缺乏关系可能源于癌细胞中药效动力学特性的差异。
