Artios Pharma Ltd., B940, Babraham Research Campus, CambridgeCB22 3FH, U. K.
Cancer Research Horizons Therapeutic Innovation, Jonas Webb Building, Babraham Research Campus, CambridgeCB22 3AT, U. K.
J Med Chem. 2022 Oct 27;65(20):13879-13891. doi: 10.1021/acs.jmedchem.2c01142. Epub 2022 Oct 6.
Human DNA polymerase theta (Polθ), which is essential for microhomology-mediated DNA double strand break repair, has been proposed as an attractive target for the treatment of BRCA deficient and other DNA repair pathway defective cancers. As previously reported, we recently identified the first selective small molecule Polθ in vitro probe, (ART558), which recapitulates the phenotype of Polθ loss, and in vivo probe, (ART812), which is efficacious in a model of PARP inhibitor resistant TNBC in vivo. Here we describe the discovery, biochemical and biophysical characterization of these probes including small molecule ligand co-crystal structures with Polθ. The crystallographic data provides a basis for understanding the unique mechanism of inhibition of these compounds which is dependent on stabilization of a "closed" enzyme conformation. Additionally, the structural biology platform provided a basis for rational optimization based primarily on reduced ligand conformational flexibility.
人类 DNA 聚合酶θ（Polθ）对于微同源介导的 DNA 双链断裂修复至关重要，已被提议作为治疗 BRCA 缺陷和其他 DNA 修复途径缺陷型癌症的有吸引力的靶标。如前所述，我们最近鉴定了第一个选择性小分子 Polθ 体外探针，（ART558），其再现了 Polθ 缺失的表型，以及体内探针，（ART812），其在 PARP 抑制剂耐药 TNBC 的体内模型中有效。在这里，我们描述了这些探针的发现、生化和生物物理特性，包括与 Polθ 的小分子配体共晶结构。晶体学数据为理解这些化合物独特的抑制机制提供了基础，该机制依赖于稳定“封闭”酶构象。此外，结构生物学平台为基于主要降低配体构象灵活性的合理优化提供了基础。
