MPN-inducing mutations as biomarkers of synthetic lethality

骨髓增生性肿瘤(MPN)，如真性红细胞增多症(PV)、原发性血小板增多症 (ET)和原发性骨髓纤维化(PMF)通常携带JAK2(V617F)、MPL(W515L)和 钙网蛋白(CALRmut)。这些异常可能伴随着TET2、ASXL1、 DNMT3A、EZH2和其他基因进一步使MPN遗传/表观遗传学的利用复杂化 签名作为治疗决策的潜在生物标记物。 目前MPNS的治疗方案包括骨髓抑制疗法，形式为 羟基脲和JAK1/2抑制剂QAK1/2I)Ruxolitinib。MPN可以有较长的慢性期， 但最终可能加速并转化为继发性急性髓系白血病 最终是致命的。因此，产生单独或联合使用的新疗法势在必行。 已经批准的药物可能会延长完全缓解时间和/或使用 在进展到恶性阶段的患者中。由于所有3个主要突变[JAK2(V617F)， 在MPN干细胞(MPNSCs)中发现了CALR(Del52)和MPL(W515L)，这些细胞一定是 为了改善治疗结果而消除。不幸的是，潜在的治疗方法 针对MPNSC的方法是有限的。 MPN细胞，包括MPNSC，积累潜在的致命性DNA双链断裂(DSB)， 它们由两个主要机制修复，BRCA介导的同源重组(HR)和 DNA-PK介导的非同源末端连接(D-NHEJ)。HR和D-NHEJ修复DSB 增殖细胞和D-NHEJ在静止期细胞中起主要作用。依赖PARP1的备份NHEJ (B-NHEJ)在增殖和静止的细胞中都起到了支持作用。 DSB修复中的癌症特异性缺陷创造了使用合成致命性的机会，例如 PARP1抑制剂(PARP1i)消除BRCA1/2突变的癌细胞然而，BRCA1/2 突变在MPN中很少见。我们假设MPN诱导的突变可以预测预后 DNA修复抑制剂触发的治疗性合成致死性的生物标记物。 我们将确定特定的MPN诱导突变(S)(生物标记物)是否会导致静止 和/或扩增个体患者的MPN干细胞和祖细胞以诱导PARP1i 合成致死率与HR和D-NHEJ抑制剂(目标1)或JAK2i(目标2)联合使用。 我们还将使用MPN和原代MPN异种移植的小鼠敲除/敲除模型 人源化免疫缺陷小鼠确定DNA修复抑制物和/或JAK2i是否发挥抗MPN作用 临床前环境中的综合致死效应(目标3)。

Myeloproliferative neoplasms (MPNs) such as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) often carry JAK2(V617F), MPL(W515L) and mutations in calreticulin (CALRmut). These aberrations may be accompanied by mutations in TET2, ASXL1, DNMT3A, EZH2, and other genes further complicating utilization of MPNs genetic/epigenetic signatures as potential biomarkers for therapeutic decisions. Current treatment options for MPNs include myelosuppressive therapy in the form of hydroxyurea and JAK1/2 inhibitor QAK1/2i) ruxolitinib. MPNs can have prolonged chronic phases, but may eventually accelerate and transform into a secondary acute myeloid leukemia that is ultimately fatal. Therefore, it is imperative to generate new therapies that alone or in combination with already approved drugs could potentially extend the complete remission time and/or be used in patients which progressed to the malignant stage. Since all 3 "main" mutations [JAK2 (V617F), CALR(del52), and MPL(W515L)] were found in MPN stem cells (MPNSCs) these cells must be eliminated in order to improve therapeutic outcome. Unfortunately, the potential therapeutic approaches against MPNSCs are limited. MPN cells, including MPNSCs accumulate potentially lethal DNA double-strand breaks (DSBs), which are repaired by two major mechanisms, BRCA-mediated homologous recombination (HR) and DNA-PK -mediated non-homologous end-joining (D-NHEJ). HR and D-NHEJ repair DSBs in proliferating cells and D-NHEJ plays a major role in quiescent cells. PARP1 -dependent back-up NHEJ (B-NHEJ) serves as back-up in both proliferating and quiescent cells. Cancer-specific defects in DSB repair create the opportunity to employ synthetic lethality, e.g. elimination of BRCA1/2-mutated cancer cells by PARP1 inhibitor (PARP1i). However, BRCA1/2 mutations are rare in MPNs. We hypothesize that MPN-inducing mutations are prognostic biomarkers of therapeutic synthetic lethality triggered by DNA repair inhibitors. We will determine if specific MPN-inducing mutation(s) (biomarkers) predispose quiescent and/or proliferating MPN stem and progenitor cells from individual patients to PARP1i-induced synthetic lethality combined with the inhibitors of HR and D-NHEJ (Aim #1) or with JAK2i (Aim #2). We will also employ murine knockin/knockout models of MPNs and primary MPN xenografts in humanized immunodeficient mice to determine if DNA repair inhibitors and/or JAK2i exert anti-MPN synthetic lethal effect in pre-clinical settings (Aim #3).