Systematic control of in vivo behavior of protein-based therapeutics is considered highly desirable for improving their clinical outcomes. Modulation of biochemical properties including molecular weight, surface charge, and binding affinity has thus been suggested to enhance their therapeutic effects. However, establishing a relationship between the binding affinity and tumor localization remains a debated issue. Here we investigate the influence of the binding affinity of proteins on tumor localization by using four repebodies having different affinities to EGFR. Biochemical analysis and molecular imaging provided direct evidence that optimal affinity with balanced target binding and dissociation can facilitate deep penetration and accumulation of protein binders in tumors by overcoming the binding-site-barrier effect. Our findings suggest that binding kinetics-based protein design can be implicated in the development of fine-tuned protein therapeutics for cancers.

体内的系统控制基于蛋白质的疗法的行为被认为是改善其临床结果的高度期望。因此已经提出了对生物化学性质的调节，包括分子量，表面电荷和结合亲和力，以增强其治疗效果。然而，建立结合亲和力和肿瘤定位之间的关系仍然是一个有争议的问题。在这里，我们通过使用对EGFR具有不同亲和力的四个repebodies，研究了蛋白质结合亲和力对肿瘤定位的影响。生化分析和分子成像提供了直接的证据，即通过克服结合位点屏障效应，具有平衡的靶标结合和解离的最佳亲和力可以促进蛋白质结合剂在肿瘤中的深入渗透和积累。