Development of novel, targeted small molecule inhibitors of DNA repair in high unmet need tumors-TNBC

DNATWO，Inc.是在加州理工学院成立的，目的是开发针对一种新癌症的小分子药物。 靶向DNA 2治疗三阴性乳腺癌（TNBC）。我们花了几十年的时间来研究 DNA 2 ATP马达驱动的核酸酶活性在减轻复制叉处的复制应激和进行DNA 2 ATP马达驱动的核酸酶活性在减轻复制叉处的复制应激中的作用。 分叉处的修复崩溃为双链断裂（DSB）。我们的科学前提是DNA 2是致命的弱点 我们可以用小分子抑制剂来靶向它。因为活性 癌基因和失活的肿瘤抑制因子导致复制应激和双链断裂（DSB）， 肿瘤的一个子集依赖于DNA 2来支持它们的生长。 乳腺癌（BC），预计2021年美国将有超过281，000例新发病例和44，000例死亡， 是女性第二常见的癌症BC是一种异质性疾病，10-15%的病例是 分类为基底样，主要是TNBC。TNBC在人类BC亚型中具有最差的预后，并且比其他亚型更严重。 在40岁以下的年轻女性中普遍存在，特别是非洲裔美国女性。结果不佳的一个因素是， 缺乏靶向治疗。我们关注DNA 2作为TNBC中的靶标与15-20%的TNBC一致。 乳腺癌易感基因BRCA 1/2缺陷的病例在对抗乳腺癌中至关重要， 复制压力。我们已经证明，DNA 2对于TNBC中的基因组稳定性和存活是重要的。 细胞系DNA 2抑制剂的治疗指数可能是由于在细胞中高的内在复制应激水平。 与正常细胞相比具有突变的致癌基因或肿瘤抑制因子的肿瘤（即致敏肿瘤细胞）， 以及存在于正常细胞中的替代性修复途径（即保护正常细胞免于 DNA 2功能丧失）。我们通过比较正常/二倍体细胞中DNA 2 i的效力， 细胞模型以及体外癌细胞系。 我们先前已经描述了小分子DNA 2抑制剂，并证明了它们的生物化学性质。 乳腺癌细胞中的体外选择性和作用模式。第一阶段的奖励将使我们能够追求两个 里程碑：Hit-to-Lead开发和体内疗效证明。Aim 1专注于Hit-to-Lead 优化最先进的DNA 2抑制剂（DNA 2 i）支架。其目标是改善药物的性质 和DNA 2的生物化学和细胞效能，而不损失靶特异性，导致具有nM 在细胞中的效力，对其他DNA修复酶的活性最低，并有希望在体外ADME性能 以支持体内测试。目标2将在小鼠PK研究中评价先导化合物，以确认体内暴露 随后进行体内小鼠TNBC异种移植研究。目标是一个前导DNA 2 i分子， 体内功效该项目的成功完成将使我们能够推进领先的优化研究， II期进一步药理学、IND使能研究（GLP、PK和毒理学）。将DNA 2 i推向临床 将为TNBC患者提供急需的治疗选择。

DNATWO, Inc. was founded out of Caltech to develop small molecule drugs targeting a new cancer target, DNA2, to treat triple-negative breast cancer (TNBC). We have spent decades unraveling the role of the DNA2 ATP-motor driven nuclease activity in relieving replication stress at the replication fork and carrying out repair at forks collapsed to double strand breaks (DSBs). Our scientific premise is that DNA2 is the Achilles’ heel of cancer cell proliferation, and that we can target it using small molecule inhibitors. Because activated oncogenes and inactivated tumor suppressors lead to replication stress and double strand breaks (DSB), a subset of tumors is dependent on DNA2 to support their growth. Breast cancer (BC), with over 281,000 new cases and 44,000 deaths expected in 2021 in the USA, is the second most common cancer in women. BC is a heterogenous disease, with 10-15% of cases being classified as basal like, predominantly TNBC. TNBC has the worst prognosis of human BC subtypes and is more prevalent in young women under 40, particularly African American women. A factor in the poor outcome is the dearth of targeted therapies. Our focus on DNA2 as a target in TNBC is consistent with 15-20% of TNBC cases being deficient in the breast cancer susceptibility genes BRCA1/2 critically important in combating replication stress. We have demonstrated that DNA2 is important for genome stability and survival in TNBC cell lines. A therapeutic index for DNA2 inhibitors is likely due to the high intrinsic levels of replication stress in tumors with mutated oncogenes or tumor suppressors as compared to normal cells (i.e. sensitizing tumor cells), as well as the presence of alternative repair pathways present in normal cells (i.e. protecting normal cells from loss of DNA2 function). We have shown this experimentally by comparing potency of DNA2i in a normal/diploid cell model as well as cancer cell lines in vitro. We have previously described small molecule DNA2 inhibitors and demonstrated their biochemical selectivity and mode of action in vitro in breast cancer cells. This Phase I award will allow us to pursue two milestones: Hit-to-Lead development and the demonstration of in vivo efficacy. Aim 1 focuses on Hit-to-Lead optimization on the most advanced DNA2 inhibitor (DNA2i) scaffolds. The goal is to improve drug-like properties and DNA2 biochemical and cellular potency without loss of target specificity, resulting in lead molecules with nM potency in cells with minimum activity against other DNA repair enzymes, and promising in vitro ADME properties to support in vivo testing. Aim 2 will evaluate lead compounds in a mouse PK study to confirm in vivo exposure followed by an in vivo mouse TNBC xenograft study. The goal is a lead DNA2i molecule with demonstrated in vivo efficacy. Successful completion of this project will allow us to advance to lead optimization studies and further pharmacology, IND-enabling studies (GLP, PK, and toxicology) in Phase II. Advancing DNA2i to the clinic will provide an urgently needed treatment option for TNBC patients.