Laboratory for Human Disease Models, RIKEN Research Center for Allergy and Immunology, Yokohama, Kanagawa 230-0045, Japan.
Sci Transl Med. 2013 Apr 17;5(181):181ra52. doi: 10.1126/scitranslmed.3004387.
Leukemia stem cells (LSCs) that survive conventional chemotherapy are thought to contribute to disease relapse, leading to poor long-term outcomes for patients with acute myeloid leukemia (AML). We previously identified a Src-family kinase (SFK) member, hematopoietic cell kinase (HCK), as a molecular target that is highly differentially expressed in human primary LSCs compared with human normal hematopoietic stem cells (HSCs). We performed a large-scale chemical library screen that integrated a high-throughput enzyme inhibition assay, in silico binding prediction, and crystal structure determination and found a candidate HCK inhibitor, RK-20449, a pyrrolo-pyrimidine derivative with an enzymatic IC50 (half maximal inhibitory concentration) in the subnanomolar range. A crystal structure revealed that RK-20449 bound the activation pocket of HCK. In vivo administration of RK-20449 to nonobese diabetic (NOD)/severe combined immunodeficient (SCID)/IL2rg(null) mice engrafted with highly aggressive therapy-resistant AML significantly reduced human LSC and non-stem AML burden. By eliminating chemotherapy-resistant LSCs, RK-20449 may help to prevent relapse and lead to improved patient outcomes in AML.
白血病干细胞（LSCs）在常规化疗后存活被认为是导致疾病复发的原因，从而导致急性髓系白血病（AML）患者的长期预后不良。我们之前发现一种 Src 家族激酶（SFK）成员，造血细胞激酶（HCK），在人类原发性 LSCs 与人类正常造血干细胞（HSCs）相比高度差异表达，是一个分子靶标。我们进行了大规模的化学文库筛选，该筛选整合了高通量酶抑制测定、计算机结合预测和晶体结构测定，并发现了一种候选 HCK 抑制剂 RK-20449，这是一种吡咯并嘧啶衍生物，其酶抑制浓度（半最大抑制浓度）在纳摩尔范围内。晶体结构显示 RK-20449 结合 HCK 的激活口袋。在非肥胖糖尿病（NOD）/严重联合免疫缺陷（SCID）/IL2rg（null）小鼠中给予 RK-20449 进行移植，这些小鼠携带高度侵袭性的耐药性 AML，显著降低了人类 LSC 和非干细胞 AML 的负担。通过消除化疗耐药的 LSCs，RK-20449 可能有助于预防复发，并改善 AML 患者的预后。
