Genomics Research Center, Academia Sinica, 128 Academia Rd., Sec. 2, Nankang Dist., Taipei, 115, Taiwan.
Institute of Pharmaceutics, Development Center for Biotechnology, Taipei, 115, Taiwan.
Sci Rep. 2021 Jul 29;11(1):15430. doi: 10.1038/s41598-021-94902-1.
Mesothelin (MSLN) is an attractive candidate of targeted therapy for several cancers, and hence there are increasing needs to develop MSLN-targeting strategies for cancer therapeutics. Antibody-drug conjugates (ADCs) targeting MSLN have been demonstrated to be a viable strategy in treating MSLN-positive cancers. However, developing antibodies as targeting modules in ADCs for toxic payload delivery to the tumor site but not to normal tissues is not a straightforward task with many potential hurdles. In this work, we established a high throughput engineering platform to develop and optimize anti-MSLN ADCs by characterizing more than 300 scFv CDR-variants and more than 50 IgG CDR-variants of a parent anti-MSLN antibody as candidates for ADCs. The results indicate that only a small portion of the complementarity determining region (CDR) residues are indispensable in the MSLN-specific targeting. Also, the enhancement of the hydrophilicity of the rest of the CDR residues could drastically increase the overall solubility of the optimized anti-MSLN antibodies, and thus substantially improve the efficacies of the ADCs in treating human gastric and pancreatic tumor xenograft models in mice. We demonstrated that the in vivo treatments with the optimized ADCs resulted in almost complete eradication of the xenograft tumors at the treatment endpoints, without detectable off-target toxicity because of the ADCs' high specificity targeting the cell surface tumor-associated MSLN. The technological platform can be applied to optimize the antibody sequences for more effective targeting modules of ADCs, even when the candidate antibodies are not necessarily feasible for the ADC development due to the antibodies' inferior solubility or affinity/specificity to the target antigen.
间皮素（MSLN）是几种癌症靶向治疗的有吸引力的候选物，因此，对于癌症治疗，开发MSLN 靶向策略的需求日益增加。针对 MSLN 的抗体药物偶联物（ADC）已被证明是治疗 MSLN 阳性癌症的可行策略。然而，将抗体作为 ADC 中的靶向模块来将毒性有效载荷递送至肿瘤部位而不是正常组织并非易事，存在许多潜在的障碍。在这项工作中，我们建立了一个高通量工程平台，通过对超过 300 个 scFv CDR 变体和超过 50 个 IgG CDR 变体进行表征，来开发和优化针对 MSLN 的 ADC，这些变体均来自于一个亲本抗 MSLN 抗体，作为 ADC 的候选物。结果表明，只有一小部分互补决定区（CDR）残基在 MSLN 特异性靶向中是不可或缺的。此外，增加其余 CDR 残基的亲水性可以极大地提高优化后的抗 MSLN 抗体的整体溶解度，从而大大提高 ADC 治疗人胃和胰腺肿瘤异种移植模型的功效。我们证明，在治疗终点时，用优化的 ADC 进行体内治疗几乎可以完全消除异种移植肿瘤，而不会因 ADC 对细胞表面肿瘤相关 MSLN 的高特异性靶向而产生可检测的脱靶毒性。该技术平台可应用于优化抗体序列，以获得更有效的 ADC 靶向模块，即使候选抗体由于其较差的溶解度或对靶抗原的亲和力/特异性而不一定适合 ADC 开发。
