KRAS与BRAF基因在胃肠间质瘤中的突变情况及临床意义

Mutation situations of KRAS and BRAF genes in gastrointestinal stromal tumors and its clinical significances

目的检测KRAS与BRAF基因在胃肠间质瘤(GIST)中的突变情况并探讨其在伊马替尼耐药中的意义。方法回顾性选择2002–2012年期间在北京大学肿瘤医院就诊的519例GIST患者,其中381例c-kit或PDGFRA突变型GIST,119例c-kit或PDGFRA野生型GIST,19例含伊马替尼耐药前后配对标本病例;检测全部肿瘤组织的KRAS外显子2与BRAF外显子15的突变情况,并收集突变患者的临床特征与生存状况。结果 KRAS基因在119例c-kit或PDGFRA野生型GIST中突变率为1.7%(2/119),突变类型分别为G12D与G12C;BRAF^(V600E)突变率也为1.7%(2/119);在c-kit或PDGFRA突变型GIST与19对耐药前后GIST配对标本中均未能检测到KRAS与BRAF基因错义突变。2例KRAS基因突变的GIST患者中1例伊马替尼原发耐药,另1例伊马替尼治疗仅获得8个月的无进展生存期;2例BRAF基因突变患者均接受肿瘤完整切除,1例中危患者术后未接受辅助治疗,截至末次随访时间获得47个月的无复发生存,另1例高危患者接受伊马替尼辅助治疗2年,截至末次随访时间,已获得7年无复发生存。结论野生型GIST患者可发生KRAS与BRAF基因低频率的突变,KRAS基因突变可能与伊马替尼原发耐药有关;继发耐药患者中未见新发的KRAS与BRAF基因突变。

Objective To detective KRAS and BRAF mutations in gastrointestinal stromal tumors （GISTs） and explore its significance in resistance of imatinib treatment. Methods Three hundred and eighty-one c-kit/PDGFRA mutation samples, 119 c-kit/PDGFRA wild type samples, and 19 pairs of samples before and after imatinib resistance from 519 patients with GIST were enrolled in this study. Polymerase chain reaction was used to detect KRAS exon 2 and BRAF exon 15 mutations. The survival data were evaluated in patients with KRAS or BRAF mutation. Results KRAS mutation was found in 2 cases （1.7%） of c-kit/PDGFRA wild type GISTs, the type of KRAS mutation was G12D and G12C, respectively. BRAFv6~~E mutation was found in 2 cases （1.7%） of wild type GISTs. No KRAS and BRAF mutations were found in the patients with the c-kit/PDGFRA mutation GISTs and pairs of GISTs before and after imatinib resistance. Two patients with KRAS mutation showed shorter progression free survivals for imatinib treatment. Two patients with BRAF mutation had longer recurrence free survivals. Conclusions Low frequency of KRAS or BRAF mutation only happens in wild type GISTs. KRAS mutation might be related to imatinib primary resistance, but not to secondary resistance.