Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90089, United States.
Department of Chemistry, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California 90089, United States.
Biochemistry. 2020 Apr 14;59(14):1420-1427. doi: 10.1021/acs.biochem.0c00046. Epub 2020 Mar 31.
Cathepsin B (CTSB) is an abundant cysteine protease that functions in both endolysosomal compartments and extracellular regions. A considerable number of preclinical and clinical studies indicate that CTSB is implicated in many human diseases. Expression levels and activity of CTSB significantly correlate with disease progression and severity. Current inhibitors of CTSB are lack of adequate specificity and pharmacological activities. Through structure-guided rational design, we hereby designed and generated a humanized antibody inhibitor targeting human CTSB. This was achieved by genetically fusing the propeptide of procathepsin B, a naturally occurring inhibitor of CTSB, into heavy chain complementarity-determining region 3 (CDR3H) of Herceptin that is used in the clinic for the treatment of breast cancer. The resulting antibody-propeptide fusion displayed high specificity for inhibiting CTSB proteolytic activity at nanomolar levels. Pharmacokinetic studies in mice revealed a plasma half-life of approximately 42 h for this anti-CTSB antibody inhibitor, comparable to that of the parental Herceptin scaffold. This study demonstrates a new approach for the efficient generation of humanized antibody inhibitors with high potency and specificity for human CTSB, which may be extended to develop antibody inhibitors against other disease relevant cathepsin proteases.
组织蛋白酶 B（CTSB）是一种丰富的半胱氨酸蛋白酶，在溶酶体隔间和细胞外区域均发挥作用。大量的临床前和临床研究表明，CTSB 与许多人类疾病有关。CTSB 的表达水平和活性与疾病的进展和严重程度显著相关。目前的 CTSB 抑制剂缺乏足够的特异性和药理学活性。通过基于结构的合理设计，我们设计并生成了一种针对人 CTSB 的人源化抗体抑制剂。这是通过将天然存在的 CTSB 抑制剂 procathepsin B 的前肽基因融合到临床上用于治疗乳腺癌的 Herceptin 的重链互补决定区 3（CDR3H）中实现的。所得的抗体-前肽融合物以纳摩尔级别的特异性抑制 CTSB 蛋白水解活性。在小鼠中的药代动力学研究表明，这种抗 CTSB 抗体抑制剂的血浆半衰期约为 42 小时，与亲本 Herceptin 支架相当。这项研究展示了一种新方法，可有效生成针对人 CTSB 的高效力和特异性的人源化抗体抑制剂，该方法可扩展到开发针对其他相关组织蛋白酶蛋白酶的抗体抑制剂。
