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

<b><i>Objective:</i></b> 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). <b><i>Methods:</i></b> 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. <b><i>Results:</i></b> 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 &lt; 0.001). Progression-free survival in the W/M group (11.0 weeks) was similar to that in the M/M group (8.0 weeks), and was significantly shorter than in the W/W group (18.0 weeks) (p &lt; 0.002). <b><i>Conclusion:</i></b> High-sensitivity KRAS mutation testing is useful for selecting true responders to cetuximab.

<b><i>研究目的：</i></b> 本研究旨在对比高灵敏度KRAS突变检测与直接测序法，在转移性结直肠癌（metastatic colorectal cancer, mCRC）患者中预测抗表皮生长因子受体抗体的治疗疗效。<b><i>研究方法：</i></b> 本研究采用直接测序法与高灵敏度检测方法——两步聚合酶链反应-限制性片段长度多态性（2-step PCR restriction fragmentation length polymorphism, RFLP），对61例接受西妥昔单抗（cetuximab）治疗的转移性结直肠癌患者的肿瘤组织开展KRAS状态分析，并针对不同突变状态下的治疗疗效进行评估。<b><i>研究结果：</i></b> 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）。本研究将受试者划分为3组：W/W组：两种方法均检测为野生型（n=29）；W/M组：直接测序检测为野生型但两步PCR-RFLP检出突变（n=11）；M/M组：两种方法均检测为突变型（n=21）。W/M组西妥昔单抗治疗的客观缓解率为0%，与M/M组无显著差异，但显著低于W/W组的41.4%（p<0.001）。W/M组的无进展生存期为11.0周，与M/M组的8.0周相近，但显著短于W/W组的18.0周（p<0.002）。<b><i>研究结论：</i></b> 高灵敏度KRAS突变检测可用于筛选西妥昔单抗的真正获益人群。