Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, The State University of New York at Buffalo, 455 Pharmacy Building, Buffalo, NY, 14214-8033, USA.
AAPS J. 2022 May 2;24(3):62. doi: 10.1208/s12248-022-00701-5.
Here, we have investigated the effect of size of protein therapeutics on brain pharmacokinetics (PK) following systemic administration in rats. All tested proteins were derived from trastuzumab that do not bind to any targets in rats. PK data generated with F(ab)(100 kDa), Fab (50 kDa), and scFv (27 kDa) fragments of trastuzumab, along with published PK data for FcRn non-binding and wild-type trastuzumab (150 kDa), were used to establish a relationship between the protein size and brain exposure. A large-pore microdialysis system was used to measure the PK of proteins in the plasma, the interstitial fluid (ISF) at the striatum (ST), and the cerebrospinal fluid (CSF) at the lateral ventricle (LV) and cisterna magna (CM). Concentrations of all the proteins in plasma, brain homogenate, ISF, and CSF were measured using ELISA. When evaluating the effect of protein size in the absence of FcRn binding, we found a bell-shaped relationship between the size and ISF/plasma AUC ratio, where 100 kDa F(ab) demonstrated the highest exposure. A similar bell-shaped relationship was observed for the brain homogenate/plasma AUC ratio, with a peak at 50 kDa. The CSF/plasma AUC ratio at LV increased monotonously with a decrease in the size of proteins. We observed that the exposure of protein therapeutics in different regions of the brain could be significantly different and there could be optimal sizes of protein therapeutics to accomplish maximum/selective exposure in selected brain regions following systemic administration.
在这里，我们研究了蛋白质治疗药物的大小对大鼠系统给药后脑药代动力学（PK）的影响。所有测试的蛋白质均源自曲妥珠单抗，而曲妥珠单抗在大鼠中不与任何靶标结合。使用曲妥珠单抗的 F(ab)(100 kDa)、Fab(50 kDa)和 scFv(27 kDa)片段的 PK 数据以及已发表的 FcRn 非结合和野生型曲妥珠单抗（150 kDa）的 PK 数据，建立了蛋白质大小与脑暴露之间的关系。使用大孔微透析系统测量了蛋白质在血浆、纹状体间质液（ISF）和侧脑室（LV）和枕骨大孔（CM）脑脊液（CSF）中的 PK。使用 ELISA 测量了所有蛋白质在血浆、脑匀浆、ISF 和 CSF 中的浓度。在评估没有 FcRn 结合的蛋白质大小的影响时，我们发现大小与 ISF/血浆 AUC 比值之间存在钟形关系，其中 100 kDa F(ab)表现出最高的暴露。脑匀浆/血浆 AUC 比值也观察到类似的钟形关系，峰值在 50 kDa。LV 的 CSF/血浆 AUC 比值随蛋白质大小的降低而单调增加。我们观察到，不同脑区的蛋白质治疗药物的暴露可能有显著差异，并且在系统给药后，在选定的脑区实现最大/选择性暴露可能存在最佳的蛋白质治疗药物大小。
