Examination of imatinib mesylate resistance in CML

描述(申请人提供)：Oehler博士的目标是在5年多的时间里前瞻性地评估慢性期(CP)CML患者对甲磺酸伊马替尼的耐药性机制，并调查至少获得MCR的患者的复发生物学。根据IRIS的研究结果，伊马替尼已成为一线治疗药物。然而，反应的持久性尚不清楚，同种异体移植仍然是唯一潜在的治疗方法。鉴于慢性粒细胞白血病治疗策略的快速变化，显然有必要在治疗早期确定反应的预测因素，最好是在治疗前。 具体目的1.评估伊马替尼的分子反应和临床预测因素。逆转录聚合酶链式反应评估bcr-abl消失的动力学可以预测异基因移植和干扰素治疗的复发和反应。Hasford评分已被用来评估接受干扰素或化疗的患者的预后。所有被分配到SWOG S0325四个分支的患者将通过RT-PCR进行评估。我们假设，在开始治疗的三到六个月内，BCR-ABL的动力学下降将与应答持续时间相关，并且Hasford评分可以预测对伊马替尼的早期应答。 具体目的2.通过基因组表达分析确定应答和复发的遗传预测因子。微阵列技术已被用于开发基因组图谱，这些基因组图谱可能比病理学或细胞遗传学更能预测预后。慢性粒细胞白血病慢性期患者的治疗前基因组反应预测因子将通过微阵列分析来确定。这些预测值将在SWOG S0325上进行前瞻性验证。我们假设，伊马替尼应答者与无应答者有不同的表达谱，低、中、高风险Hasford评分将有不同的基因表达谱与结果相关。 具体目的3.通过点突变分析和基因组表达分析确定复发的生物学机制。对伊马替尼耐药的几种机制已有描述。点突变的发生率将通过PCR-SSCP和敏感的错配分析来评估，以确定治疗前和治疗早期的点突变频率。我们假设突变频率很高，在治疗前是可以检测到的。将复发样本的基因表达模式与相应的诊断样本进行比较。我们假设，以前未被检测到的克隆的进化是复发的机制。

DESCRIPTION (provided by applicant): Dr. Oehler's objective over 5 years is to prospectively assess mechanisms of resistance to imatinib mesylate in chronic phase (CP) CML patients and investigate the biology of relapse in patients who have obtained at least a MCR. Imatinib has become first line therapy based on the IRIS study results. However, the durability of response is unknown, and allogeneic transplant remains the only potential cure. Given the rapid change in treatment strategy for CML there is a clear need to identify predictors of response early in therapy, ideally pre-treatment. Specific Aim 1. Assess molecular response and clinical predictors of response to imatinib. The kinetics of bcr-abl disappearance as assessed by RT-PCR predict relapse and response to allogeneic transplant and interferon therapy. The Hasford score has been utilized to assess prognosis in patients treated with interferon or chemotherapy. All patients assigned to the four arms of SWOG S0325 will be assessed by RTPCR. We hypothesize that the kinetics of bcr-abl decrease within three to six months of initiating treatment will correlate with duration of response, and that the Hasford score predicts early response to imatinib. Specific Aim 2. Determine the genetic predictors of response and relapse by genomic expression analysis. Microarray technology has been used to develop genomic profiles that may be more predictive of prognosis than pathology or cytogenetics. Pre-treatment genomic predictors of response will be identified in chronic phase CML patients by microarray analysis. These predictors will be validated prospectively on SWOG S0325. We hypothesize that imatinib responders will have different expression profiles than non-responders and that low, intermediate, and high risk Hasford scores will have distinct gene expression profiles that correlate with outcome. Specific Aim 3. Determine the biology of relapse by point mutation analysis and genomic expression analysis. Several mechanisms of resistance to imatinib have been described. The prevalence of point mutations will be assessed by PCR-SSCP and by a sensitive mismatch assay to determine the frequency of point mutations pre- and early in treatment. We hypothesize that mutations frequency is high and is detectable before treatment. The gene expression pattern of the relapsed sample will be compared with the corresponding diagnostic sample. We hypothesize that the evolution of a previously undetected clone is the mechanism of relapse.