Structure Based Design of Pol-theta inhibitors

急性髓系白血病(AML)是成人最常见的急性白血病诊断形式，标准 包括化疗和/或干细胞移植在内的护理治疗只能治愈30%-40%的患者。近期 研究表明，具有Flt3受体激活内串联复制(ITD)突变的AML(Flt3(ITD)- 同源重组(HR)的BRCA1/2通路出现缺陷 使用酪氨酸激酶抑制剂(TKI)治疗。BRCA缺乏症对DNA损伤和/或 DNA修复抑制，从而为AML提供了一种有前途的新的治疗策略。我们发现 BRCA缺陷型白血病细胞高度依赖DNA修复酶DNA聚合酶 (POLθ)，对正常细胞和小鼠来说是必不可少的。POLθ参与跨损伤合成 微同源介导的末端连接(MMEJ)双链断裂(DSB)修复途径。我们最大的小- 分子POLθ抑制剂(POLθI)杀死与TKI Quizartinib共同处理的急性髓系白血病患者细胞，从而导致 缺乏BRCA，而奎扎替尼和POLθI作为单药显示的杀伤力显著降低。这些 数据显示，POLθI+TKI是治疗Flt3(ITD)阳性急性髓细胞白血病的一种有前途的治疗策略。 POLθI在体外和体内也显示出对其他BRCA缺陷性白血病(ALL，慢性粒细胞白血病)的优先杀伤作用，尤其是 与TKI相结合。总之，我们数据发现POLθ是白血病的一个新的药物靶点，并证明了 POLθI+TKI是一种有前景的治疗策略，特别是在侵袭性Flt3(ITD)阳性的急性髓细胞白血病中。在第一阶段， 重组治疗有限责任公司(RTX)，一家初创的精确肿瘤学公司，计划增加效力 我们领先的POLθI作为治疗Flt3(IDT)阳性急性髓细胞白血病的新疗法的X射线结晶学和结构 基于以下目标的优化设计：1.解决POLDNA-θ的共晶结构-- POLθI三元配合物；2.采用基于结构的优化设计对POLθI进行优化。 在第二阶段，RTX的目标是实现以下目标：1.进一步开发我们领先的POLθI候选药物 通过获得更有利的ADME和药代动力学参数；2.表征优化的POLθI 联合TKI在体内建立Flt3(IDT)阳性AML动物模型。

Acute myeloid leukemia (AML) is the most frequently diagnosed form of acute leukemia in adults, and standard of care treatment involving chemotherapy and/or stem cell transplantation only cures 30-40% of patients. Recent studies show that AMLs with FLT3 receptor activating internal tandem duplication (ITD) mutations (FLT3(ITD)- positive AMLs) become defective in the BRCA1/2 pathway of homologous recombination (HR) following treatment with tyrosine kinase inhibitors (TKi). BRCA-deficiency confers strong sensitivity to DNA damage and/or DNA repair inhibition, and thus presents a promising new therapeutic strategy for AML. We discovered that BRCA-deficient leukemia cells are hyper-dependent on the DNA repair enzyme DNA polymerase theta (Polθ), which is dispensable for normal cells and mice. Polθ is involved in translesion synthesis and the microhomology-mediated end-joining (MMEJ) double-strand break (DSB) repair pathway. Our leading small- molecule Polθ inhibitor (Polθi) kills AML patient cells co-treated with the TKi quizartinib which causes BRCA-deficiency, whereas quizartinib and Polθi as single agents shows significantly less killing. These data demonstrate the Polθi + TKi combination as a promising therapeutic strategy for FLT3(ITD)-positive AML. Polθi also shows preferential killing of other BRCA-deficient leukemias (ALL, CML) in vitro and in vivo, especially in combination with TKi. In summary, our data discover Polθ as a novel drug target in leukemia, and demonstrate Polθi + TKi as a promising therapeutic strategy, especially in aggressive FLT3(ITD)-positive AML. In phase I, Recombination Therapeutics, LLC (RTx), a start-up precision oncology company, plans to increase the potency of our leading Polθi as a novel treatment for FLT3(IDT)-positive AML using X-ray crystallography and structure based optimization/design by developing the following Aims: 1. To solve the co-crystal structure of Polθ-DNA- Polθi ternary complexes; 2. To optimize Polθi using structure based optimization/design. In Phase II, RTx aims to achieve the following goals: 1. Further develop our leading Polθi drug candidate by achieving more favorable ADME and pharmacokinetic parameters; 2. Characterize optimized Polθi in combination with TKi in FLT3(IDT)-positive AML animal models in vivo.