Supplementary Material for: Clinical Benefit of High-Sensitivity KRAS Mutation Testing in Metastatic Colorectal Cancer Treated with Anti-EGFR Antibody Therapy

Objective: We compared high-sensitivity KRAS mutation testing with direct sequencing for predicting the efficacy of antiepidermal growth factor receptor antibodies in patients with metastatic colorectal cancer (mCRC). Methods: We analyzed the KRAS status in 61 tumors from cetuximab-treated mCRC patients by both direct sequencing and a high-sensitivity method: 2-step PCR restriction fragmentation length polymorphism (RFLP). Therapeutic effects in each mutational status were evaluated. Results: The incidences of KRAS mutations determined by direct sequencing and 2-step PCR RFLP were 34.4 and 52.5%, respectively (p = 0.02). Patients were categorized into 3 groups [W/W, wild-type by both methods (n = 29); W/M, wild-type by direct sequencing, detected mutation by 2-step PCR RFLP (n = 11); M/M, mutant-type by both methods (n = 21)]. The response rate for cetuximab in the W/M group (0%) was the same as that in the M/M group, and was significantly lower than in the W/W group (41.4%) (p Conclusion: High-sensitivity KRAS mutation testing is useful for selecting true responders to cetuximab.

研究目的：本研究对比高灵敏度KRAS基因突变检测与直接测序法（direct sequencing），评估二者在预测转移性结直肠癌（metastatic colorectal cancer, mCRC）患者对抗表皮生长因子受体抗体（antiepidermal growth factor receptor antibodies）治疗疗效中的应用价值。
研究方法：本研究采用直接测序法与高灵敏度检测方案——两步聚合酶链反应-限制性片段长度多态性（2-step PCR restriction fragment length polymorphism, RFLP），对61例接受西妥昔单抗（cetuximab）治疗的mCRC患者的肿瘤组织开展KRAS状态分析，并评估不同突变状态下的治疗应答情况。
研究结果：直接测序法与两步PCR-RFLP检测所得的KRAS突变发生率分别为34.4%与52.5%（p=0.02）。根据检测结果将患者分为3组：W/W组，两种方法均检测为野生型（n=29）；W/M组，直接测序法检测为野生型但两步PCR-RFLP检测出突变（n=11）；M/M组，两种方法均检测为突变型（n=21）。W/M组患者的西妥昔单抗应答率为0%，与M/M组持平，且显著低于W/W组的41.4%（p
研究结论：高灵敏度KRAS基因突变检测可用于精准筛选西妥昔单抗的真正获益应答人群。