确定O⁶-甲基鸟嘌呤-DNA甲基转移酶高甲基化作为维利帕尼介导的替莫唑胺对胶质母细胞瘤致敏治疗的生物标志物

Delineation of MGMT Hypermethylation as a Biomarker for Veliparib-Mediated Temozolomide-Sensitizing Therapy of Glioblastoma.

作者信息

Gupta Shiv K, Kizilbash Sani H, Carlson Brett L, Mladek Ann C, Boakye-Agyeman Felix, Bakken Katrina K, Pokorny Jenny L, Schroeder Mark A, Decker Paul A, Cen Ling, Eckel-Passow Jeanette E, Sarkar Gobinda, Ballman Karla V, Reid Joel M, Jenkins Robert B, Verhaak Roeland G, Sulman Erik P, Kitange Gaspar J, Sarkaria Jann N

机构信息

Department of Radiation Oncology (SKG, BLC, ACM, KKB, JLP, MAS, LC, GJK, JNS), Division of Medical Oncology (SHK), Molecular Pharmacology and Experimental Therapeutics (FBA, JMR), Division of Biomedical Statistics and Informatics (PAD, JEEP, KVB), and Laboratory Medicine and Pathology (GS, RBJ), Mayo Clinic, Rochester MN; The University of Texas, MD Anderson Cancer Center, Houston, TX (RGV, EPS).

出版信息

J Natl Cancer Inst. 2015 Nov 27;108(5). doi: 10.1093/jnci/djv369. Print 2016 May.

DOI:10.1093/jnci/djv369

PMID:26615020

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4862419/

Abstract

BACKGROUND

Sensitizing effects of poly-ADP-ribose polymerase inhibitors have been studied in several preclinical models, but a clear understanding of predictive biomarkers is lacking. In this study, in vivo efficacy of veliparib combined with temozolomide (TMZ) was evaluated in a large panel of glioblastoma multiforme (GBM) patient-derived xenografts (PDX) and potential biomarkers were analyzed.

METHODS

The efficacy of TMZ alone vs TMZ/veliparib was compared in a panel of 28 GBM PDX lines grown as orthotopic xenografts (8-10 mice per group); all tests of statistical significance were two-sided. DNA damage was analyzed by γH2AX immunostaining and promoter methylation of DNA repair gene O6-methylguanine-DNA-methyltransferase (MGMT) by Clinical Laboratory Improvement Amendments-approved methylation-specific polymerase chain reaction.

RESULTS

The combination of TMZ/veliparib statistically significantly extended survival of GBM models (P < .05 by log-rank) compared with TMZ alone in five of 20 MGMT-hypermethylated lines (average extension in median survival = 87 days, range = 20-150 days), while the combination was ineffective in six MGMT-unmethylated lines. In the MGMT promoter-hypermethylated GBM12 line (median survival with TMZ+veliparib = 189 days, 95% confidence interval [CI] = 59 to 289 days, vs TMZ alone = 98 days, 95% CI = 49 to 210 days, P = .04), the profound TMZ-sensitizing effect of veliparib was lost when MGMT was overexpressed (median survival with TMZ+veliparib = 36 days, 95% CI = 28 to 38 days, vs TMZ alone = 35 days, 95% CI = 32 to 37 days, P = .87), and a similar association was observed in two nearly isogenic GBM28 sublines with an intact vs deleted MGMT locus. In comparing DNA damage signaling after dosing with veliparib/TMZ or TMZ alone, increased phosphorylation of damage-responsive proteins (KAP1, Chk1, Chk2, and H2AX) was observed only in MGMT promoter-hypermethylated lines.

CONCLUSION

Veliparib statistically significantly enhances (P < .001) the efficacy of TMZ in tumors with MGMT promoter hypermethylation. Based on these data, MGMT promoter hypermethylation is being used as an eligibility criterion for A071102 (NCT02152982), the phase II/III clinical trial evaluating TMZ/veliparib combination in patients with GBM.

摘要

背景

聚-ADP-核糖聚合酶抑制剂的致敏作用已在多种临床前模型中进行了研究，但对预测性生物标志物仍缺乏清晰的认识。在本研究中，我们在大量多形性胶质母细胞瘤（GBM）患者来源的异种移植瘤（PDX）中评估了维利帕尼联合替莫唑胺（TMZ）的体内疗效，并分析了潜在的生物标志物。

方法

在一组28个作为原位异种移植瘤生长的GBM PDX系中比较了单独使用TMZ与TMZ/维利帕尼的疗效（每组8 - 10只小鼠）；所有统计学显著性检验均为双侧检验。通过γH2AX免疫染色分析DNA损伤，并通过临床实验室改进修正案批准的甲基化特异性聚合酶链反应分析DNA修复基因O6-甲基鸟嘌呤-DNA-甲基转移酶（MGMT）的启动子甲基化。

结果

在20个MGMT高甲基化系中的5个中，与单独使用TMZ相比，TMZ/维利帕尼联合用药在统计学上显著延长了GBM模型的生存期（对数秩检验P <.05）（中位生存期平均延长 = 87天，范围 = 20 - 150天），而该联合用药在6个MGMT未甲基化系中无效。在MGMT启动子高甲基化的GBM12系中（TMZ + 维利帕尼治疗的中位生存期 = 189天，95%置信区间[CI] = 59至289天，单独使用TMZ为98天，95%CI = 49至210天，P =.04），当MGMT过表达时，维利帕尼对TMZ的显著致敏作用消失（TMZ + 维利帕尼治疗的中位生存期 = 36天，95%CI = 28至38天，单独使用TMZ为35天，95%CI = 32至37天，P =.87），并且在两个MGMT基因座完整与缺失的近等基因GBM28亚系中也观察到了类似的关联。在比较维利帕尼/TMZ或单独使用TMZ给药后的DNA损伤信号传导时，仅在MGMT启动子高甲基化系中观察到损伤反应蛋白（KAP1、Chk1、Chk2和H2AX）的磷酸化增加。