Department of Immunology and Microbiology, The Scripps Research Institute, Jupiter, FL 33458, USA.
Biomolecules. 2020 May 14;10(5):764. doi: 10.3390/biom10050764.
The interest in replacing the conventional immunoglobulin G (IgG) format of monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs) with alternative antibody and antibody-like scaffolds reflects a need to expand their therapeutic utility and potency while retaining their exquisite specificity, affinity, and low intrinsic toxicity. For example, in the therapy of solid malignancies, the limited tumor tissue penetration and distribution of ADCs in IgG format mitigates a uniform distribution of the cytotoxic payload. Here, we report triple variable domain Fab (TVD-Fab) as a new format that affords the site-specific and stable generation of monovalent ADCs without the Fc domain and a drug-to-antibody ratio (DAR) of 2. TVD-Fabs harbor three variable fragment (Fv) domains: one for tumor targeting and two for the fast, efficient, precise, and stable conjugation of two cargos via uniquely reactive lysine residues. The biochemical and in vitro cytotoxicity properties of a HER2-targeting TVD-Fab before and after conjugation to a tubulin inhibitor were validated. In vivo, the TVD-Fab antibody carrier revealed a circulatory half-life of 13.3 ± 2.5 h and deeper tumor tissue distribution compared to our previously reported dual variable domain (DVD)-IgG1 format. Taken together, the TVD-Fab format merits further investigations as an antibody carrier of site-specific ADCs targeting solid malignancies.
人们对用替代抗体和抗体样支架来替代传统的免疫球蛋白 G（IgG）形式的单克隆抗体（mAb）和抗体药物偶联物（ADC）的兴趣，反映了需要扩大其治疗用途和效力，同时保持其高度特异性、亲和力和低固有毒性。例如，在实体瘤的治疗中，ADC 在 IgG 形式下的有限肿瘤组织穿透性和分布减轻了细胞毒性有效载荷的均匀分布。在这里，我们报告了三重可变结构域 Fab（TVD-Fab）作为一种新的形式，它可以通过独特的反应性赖氨酸残基进行定点且稳定地产生单价 ADC，而无需 Fc 结构域和药物抗体比（DAR）为 2。TVD-Fab 含有三个可变片段（Fv）结构域：一个用于肿瘤靶向，另外两个用于通过两个独特反应性赖氨酸残基快速、高效、精确和稳定地连接两个有效载荷。在与微管抑制剂缀合之前和之后，对针对 HER2 的 TVD-Fab 的生化和体外细胞毒性特性进行了验证。在体内，与我们之前报道的双可变结构域（DVD）-IgG1 形式相比，TVD-Fab 抗体载体显示出 13.3 ± 2.5 h 的循环半衰期和更深的肿瘤组织分布。总之，TVD-Fab 形式值得进一步研究，作为针对实体瘤的定点 ADC 的抗体载体。
