Abstract A201: Mutation profiling and prognostic value of BRAF, HRAS, KRAS, MET, NRAS, PIK3CA, KRASG12V in colon cancer: Results from NSABP C-07
Authors: Pogue-Geile Kay L. , Fumagalli Debora , Gavin Patrick G. , Colangelo Linda , Taniyama Yusuke , Kim Seung-Il , Choi Hyun-Joo , Kim Chung , Kuebler J. Philip , Geyer Charles E. , Petrelli Nick , O'Connell Michael J. , Yothers Greg , Paik Soonmyung , Wolmark Norman 
Published: June 2012

More than 20% of patients with resected stage II colon cancer and 50% of patients with resected stage III colon cancer will develop recurrence. To identify markers for recurrence and to find potentially new targets for treatment, mutations were profiled in tumors from NSABP clinical trial C-07. TypePLEX chemistry and the Mass Array system from Sequenom (SanDiego CA) were used to profile 238 common, hot-spot, cancer mutations in 19 genes in 239 colon cancer samples utilizing the OncoCarta panel. Mutations were detected in 7 different genes (ABL1, AKT1, BRAF, KRAS, MET, NRAS and PIK3CA) at 26 different nucleotide positions. Twenty-four assays which detected mutations in more than 1% of the samples were reconfigured into a new multiplexed panel, termed here as ColoCarta, and used to repeat the profiling of 24 mutant samples. These profiles were identical to those found with OncoCarta, demonstrating reproducibility. The method was also sensitive, requiring as little as 1ng of input DNA. In some assays it was possible to detect mutations that represented only 5% of the alleles, an important consideration for heterogeneous tumor tissue. An additional 869 tumors from C-07 were profiled with ColoCarta. Data from a 1035 eligible C07 patients with follow-up were analyzed with Cox PH models, controlling for treatment, number of positive nodes, age and gender. Each gene (BRAF, HRAS, KRAS, MET, NRAS and PIK3CA), a specific mutation KRASG12V and mutations in any gene were examined as dichotomous variables. Only NRAS mutations were significant predictors of recurrence (HR= 1.79, p=0.049) (Table 1). In conclusion, this study presents a rapid, sensitive, reproducible and cost effective method for mutation profiling of both infrequent (ABL1, AKT1, NRAS) and frequent (BRAF, KRAS and PIK3CA) mutations and also identified mutations new to colon cancer in the MET oncogene. MET has been shown to promote many metastatic activities and may provide a new target for colon cancer treatment in a subset of patients.

Table 1 C07 Gene Mutation Subset, First Recurrence Variable (range Without Mutation Recur/N (% Recur) With Mutation Recur/N (% Recur) Dichotomous (Any Mutation) P-value Hazard Ratio* 95% CI BRAF (0,1) 237/879 (27.0) 46/153 (30.1) 0.5994 1.091 0.79–1.51 HRAS (0,1) 283/1029 (27.5) 1/6 (16.7) 0.8214 0.797 0.11-5.71 KRAS (0,1,2) 167/632 (26.4) 115/400 (28.8) 0.3482 1.121 0.88–1.42 KRAS G12V (0,1) 253/947 (26.7) 31/88 (35.2) 0.0714 1.410 0.97–2.05 MET (0,1,2,) 273/1002 (27.2) 11/33 (33.3) 0.4017 1.295 0.71–2.37 NRAS (0,1,2) 270/1001 (27.0) 12/29 (41.4) 0.0488 1.792 1.00–3.20 PIK3CA (0, 1, 2) 230/817 (28.2) 54/213 (25.4) 0.9390 1.012 0.75–1.36 Total Number of Mutations (0–3) 92/370 (24.9) 192/665 (28.9) 0.0874 1.246 0.97–1.60 * The hazard ratio compares the hazard in patients with the mutation to patients without the mutation.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A201.