Turner Joel G, Dawson Jana L, Grant Steven, Shain Kenneth H, Dalton William S, Dai Yun, Meads Mark, Baz Rachid, Kauffman Michael, Shacham Sharon, Sullivan Daniel M
Chemical Biology and Molecular Medicine Program, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, USA.
Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA.
J Hematol Oncol. 2016 Aug 24;9(1):73. doi: 10.1186/s13045-016-0304-z.
Acquired drug resistance is the greatest obstacle to the successful treatment of multiple myeloma (MM). Despite recent advanced treatment options such as liposomal formulations, proteasome inhibitors, immunomodulatory drugs, myeloma-targeted antibodies, and histone deacetylase inhibitors, MM is still considered an incurable disease.
We investigated whether the clinical exportin 1 (XPO1) inhibitor selinexor (KPT-330), when combined with pegylated liposomal doxorubicin (PLD) or doxorubicin hydrochloride, could overcome acquired drug resistance in multidrug-resistant human MM xenograft tumors, four different multidrug-resistant MM cell lines, or ex vivo MM biopsies from relapsed/refractory patients. Mechanistic studies were performed to assess co-localization of topoisomerase II alpha (TOP2A), DNA damage, and siRNA knockdown of drug targets.
Selinexor was found to restore sensitivity of multidrug-resistant 8226B25, 8226Dox6, 8226Dox40, and U266PSR human MM cells to doxorubicin to levels found in parental myeloma cell lines. NOD/SCID-γ mice challenged with drug-resistant or parental U266 human MM and treated with selinexor/PLD had significantly decreased tumor growth and increased survival with minimal toxicity. Selinexor/doxorubicin treatment selectively induced apoptosis in CD138/light-chain-positive MM cells without affecting non-myeloma cells in ex vivo-treated bone marrow aspirates from newly diagnosed or relapsed/refractory MM patients. Selinexor inhibited XPO1-TOP2A protein complexes (proximity ligation assay), preventing nuclear export of TOP2A in both parental and multidrug-resistant MM cell lines. Selinexor/doxorubicin treatment significantly increased DNA damage (comet assay/γ-H2AX) in both parental and drug-resistant MM cells. TOP2A knockdown reversed both the anti-tumor effect and significantly reduced DNA damage induced by selinexor/doxorubicin treatment.
The combination of an XPO1 inhibitor and liposomal doxorubicin was highly effective against acquired drug resistance in in vitro MM models, in in vivo xenograft studies, and in ex vivo samples obtained from patients with relapsed/refractory myeloma. This drug combination synergistically induced TOP2A-mediated DNA damage and subsequent apoptosis. In addition, based on our preclinical data, we have initiated a phase I/II study with the XPO1 inhibitor selinexor and PLD (ClinicalTrials.gov NCT02186834). Initial results from both preclinical and clinical trials have shown significant promise for this drug combination for the treatment of MM.
获得性耐药是成功治疗多发性骨髓瘤（MM）的最大障碍。尽管最近有脂质体制剂、蛋白酶体抑制剂、免疫调节药物、骨髓瘤靶向抗体和组蛋白去乙酰化酶抑制剂等先进的治疗选择，但MM仍被认为是一种无法治愈的疾病。
我们研究了临床出口蛋白1（XPO1）抑制剂塞利尼索（KPT-330）与聚乙二醇化脂质体阿霉素（PLD）或盐酸阿霉素联合使用时，是否能克服多药耐药的人MM异种移植瘤、四种不同的多药耐药MM细胞系或复发/难治性患者的体外MM活检组织中的获得性耐药。进行了机制研究以评估拓扑异构酶IIα（TOP2A）的共定位、DNA损伤以及药物靶点的siRNA敲低情况。
发现塞利尼索可将多药耐药的8226B25、8226Dox6、8226Dox40和U266PSR人MM细胞对阿霉素的敏感性恢复到亲代骨髓瘤细胞系中的水平。用耐药或亲代U266人MM攻击并接受塞利尼索/PLD治疗的NOD/SCID-γ小鼠肿瘤生长显著减少，生存期延长，且毒性最小。塞利尼索/阿霉素治疗在体外处理的新诊断或复发/难治性MM患者的骨髓抽吸物中选择性诱导CD138/轻链阳性MM细胞凋亡，而不影响非骨髓瘤细胞。塞利尼索抑制XPO1-TOP2A蛋白复合物（邻近连接分析），阻止TOP2A在亲代和多药耐药MM细胞系中的核输出。塞利尼索/阿霉素治疗显著增加亲代和耐药MM细胞中的DNA损伤（彗星试验/γ-H2AX）。TOP2A敲低逆转了抗肿瘤作用，并显著降低了塞利尼索/阿霉素治疗诱导的DNA损伤。
XPO1抑制剂与脂质体阿霉素联合在体外MM模型、体内异种移植研究以及从复发/难治性骨髓瘤患者获得的体外样本中对获得性耐药具有高度有效性。这种药物组合协同诱导TOP2A介导的DNA损伤及随后的凋亡。此外，基于我们的临床前数据，我们已启动了一项使用XPO1抑制剂塞利尼索和PLD的I/II期研究（ClinicalTrials.gov NCT02186834）。临床前和临床试验的初步结果均显示这种药物组合在治疗MM方面具有显著前景。
