Role Of KRAS Mutations Research Articles

Role of KRAS mutation in advanced ovarian cancers treated by targeted medicines in Thailand.

e22072 Background: The treatment of advanced ovarian cancer has been surgery followed by various forms of chemotherapeutic agents. Once the chemotherapeutic agents failed to achieve the response, the option left is rather diamal. Recent advances in targeted medicines along with specific genes study allowed us to study this group of patients. Our objective is to 1) to determineKRAS mutation in all ovarian cancers treated by targeted medicines 2) To compare the response of patients with KRAS mutation versus those without KRAS mutation 3) To modulate the treatment in the presence of KRAS mutation. Methods: 25 cases of advanced and recurred (stage IV) ovarian cancers who had exhausted all chemotherapeutic treatment were included in the study. To select the targetsfor the treatment, we examined the VEGF, EGFR,cKIT and HER2 genes using IHC ( Immunohistochemical) technique with additional DNA study. KRAS mutation was studied by DNA sequencing technique. Treatment targeted medicines used: 13 cases of Bevacizumab+ sunitinib, 4 cases of Bevacizumab+ EGFR TKI, 6 cases of Bevacizumab + Anti-EGFR monoclonal antibody and 2 cases of Bevacizumab+ trastuzumab. Results: 1) KRAS mutations were found in 10 of 25 cases (40%). Types of mutation included; 3 cases of G12D mutation, 4 cases of G12V mutation, 2 cases of G12C mutation and 1 case of G13D mutation. 2) Responses: Those with KRAS mutation showed 3 months response of 3/10 (30%) and those without KRAS mutation showed 3 months response of 9/15 ( 60%). For one year response: Those with KRAS mutation showed 1/10 (10%) and those without KRAS mutation showed 5/15 (33%) one year response. Conclusions: 1) Type of KRAS mutation played no role in achieving response. 2) Cases with KRAS mutation represented the overall poor prognosis. 3) At present, we have been using mTOR inhibitor in order to block PI-3K signal transduction pathway in KRAS mutation patients with some degrees of success.

BRAF and KRAS mutations in liver-resected metastatic colorectal cancer (mCRC) patients (pts).

476 Background: Up today there are no molecular markers to identify mCRC pts candidate to curative liver surgery at high risk of relapse. There are conflicting results about the prognostic role of KRAS mutation in mCRC pts, while BRAF mutation is a well-known negative prognostic factor characterizing a subgroup of mCRCs with a distinct metastatic spread. We analyzed the impact of BRAF and KRAS mutations on relapse free-survival (RFS) and overall survival (OS) in pts undergoing liver resection with curative intent. Methods: Medical records of pts referred to 3 Italian institutions between 1995 and 2012 were reviewed. 3024 mCRC pts were identified. 401 pts (13.3%) underwent liver resection with curative intent and had adequate follow-up. Mutational status was assessable on 360 samples from primary tumors (n=63), metastases (mts) (n=59) or both (n=238). Primary objective was to evaluate the impact of BRAF mutation on RFS in mCRC pts candidate to liver resection. Secondary objectives were to evaluate the prognostic role of BRAF status on OS, and of KRAS status on RFS and OS in this population. Results: BRAF and KRAS were mutated in 11 (3%) and 116 (32%) out of 360 cases respectively. In 238 cases in which paired samples from primary and metastases were available, no discordance was found in BRAF status while 18 cases (7.6%) showed a discrepancy in KRAS status and were thus excluded from analysis. Pts with BRAF mutation had significantly shorter median RFS compared to pts with BRAF wt tumor (5.7 mos vs 11.7 mos, HR=4.25; 95%CI: 1.52-11.88, p=0.005). OS was significantly reduced in pts with BRAF mutated tumors vs wt (HR=5.39; 95%CI: 1.59-18.27, p=0.007). Mutated KRAS was not prognostic for RFS (HR=1.14; 95%CI: 0.87-1.49, p=0.34), while demonstrated a weak prognostic impact on OS (HR=1.52; 95%CI: 1.05-2.21, p=0.03). In this cohort high-risk Fong score were significantly associated with shorter RFS (p<0.0001) and OS (p<0.0001). Conclusions: BRAF mutation is associated with higher probability of relapse and worse outcome in liver resected mCRC. KRAS mutation was not associated with RFS after liver resection. BRAF mutational status may become a new prognostic marker when planning liver resection in mCRC pts.

Association between KRAS mutation and lung metastasis in advanced colorectal cancer.

494 Background: The role of KRAS status in the time-dependent pattern of metastasis in colorectal cancer (CRC) patients has been reported but not validated in independent series of unresectable metastatic CRC. We aimed to determine its potential value as a predictive factor for development of lung metastasis. Methods: We retrospectively evaluated data from MD Anderson Cancer Center from 494 patients diagnosed with metastatic CRC with KRAS mutation testing (codons 12, 13, 61) by Sanger sequencing or mass spectroscopy genotyping in 2008 through 2010. Medical records and image reports were assessed to determine date of lung metastasis diagnosis, pattern of lung involvement and presence of thoracic lymph nodal metastasis. Time-to-lung metastasis (TTLM), lung-metastasis-free survival (LMFS) and overall survival (OS) were calculated from the time of diagnosis of first metastasis in any site according to the Kaplan-Meier method and were compared by log-rank test. Results: We included 494 patients (41% female) with a median age of 55 years. 292 tumors were KRAS wild type (WT, 59%) and 202 (41%) were KRAS mutants. OS was not different between the groups (45.5 months for KRAS mutants vs. 50.6 months for KRAS wild type; p=0.6). At the time of diagnosis of metastatic disease, 36% of patient had lung metastases, with 1.6-fold higher odds of lung metastases with a KRAS mutation (p=0.013, 95% CI 1.1 – 2.4). Compared to KRAS WT, KRAS mutations were associated with a shorter TTLM (15.2 vs. 22.4 months; p=0.002) and LMFS (12.9 vs. 16.7 months; p= 0.019). There was no difference in thoracic lymph node involvement (p= 0.18), number of lung metastasis (p=0.71), lung lobes involved (p=0.19) or disease in bilateral lung (p=0.27) according to KRAS status. There were no differences in lung metastasis frequency or pattern between codons 12, 13, and 61 mutations. Conclusions: In this retrospective analysis, lung metastases were more common at diagnosis of mCRC in KRAS mutant patients and more likely to develop during the disease course. This data suggests a potential role for KRAS mutations in determining a metastatic tropism of CRC to the lung and can be used to risk stratify patients.

Dose KRAS Mutation Status Affect on the Effect of VEGF Therapy in Metastatic Colon Cancer Patients?

PurposeMutations affecting the KRAS gene are an established negative predictor for anti-epidermal growth factor receptor (anti-EGFR) therapies in metastatic colorectal cancer (CRC). However, the role of KRAS mutation as a biomarker for anti-vascular endothelial growth factor (VEGF) remains controversial.Materials and MethodsWe analyzed retrospective data from 32 CRC patients who were available for KRAS mutation status and received cytotoxic chemotherapy plus bevacizumab as a first-line therapy. Six of 32 patients received anti-EGFR therapies. We used KRAS mutation status as a predictive or prognostic factor in CRC patients receiving bevacizumab.ResultsWe observed mutations in KRAS in 59.4% of patients. Bevacizumab was used in combination with oxaliplatin based regimens. There was no significant difference for progression free survival (PFS) and overall survival (OS) in patients with oxaliplatin based cytotoxic chemotherapy plus bevacizumab according to the status of KRAS mutation. After first-line therapy, 28 patients (87.5%) received second-line therapy. In univariate analysis, KRAS mutations did not have a major prognostic value for PFS (hazard ratio, 1.007; 95% confidence interval [CI], 0.469 to 2.162; p>0.05) or OS (hazard ratio, 0.548; 95% CI, 0.226 to 1.328; p>0.05). In addition, anti-EGFR therapies did not affect the impact on OS.ConclusionKRAS mutation is neither a predictive for bevacizumab nor a prognostic for OS in CRC patients receiving anti-VEGF therapy.

RAS mutations: impact on treatment outcome

SUMMARY RAS proteins belong to the MAPK network, an essential pathway for maintenance of normal vital processes such as proliferation and differentiation. RAS mutations are observed in 30–50% of colorectal carcinomas. The MAPK pathway and RAS proteins are part of a complex system that mediate signaling from the EGF receptors (EGFRs). Our review discusses the most recent evidence highlighting the role of KRAS mutations in patients who are offered anti-EGFR therapy. Furthermore, we discuss emerging evidence of the role of other predictive markers such as PI3K, PTEN, BRAF, NRAS, MET, IGFR-1 and p53 in patients who are receiving anti-EGFR therapy.

KRAS Mutations in Advanced Nonsquamous Non–Small-Cell Lung Cancer Patients Treated with First-Line Platinum-Based Chemotherapy Have No Predictive Value

Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation is thought to be related with dismal outcome for non-small-cell lung cancer (NSCLC) patients. The role of KRAS mutation as a predictor of response to chemotherapy for patients with metastatic NSCLC is poorly understood. From a retrospective database of two university hospitals, all patients with advanced, nonsquamous NSCLC treated with first-line platinum-containing chemotherapy were selected. Mutation analysis for KRAS was performed and the relation with response to chemotherapy was assessed. Secondary endpoints were its relation with response to progression-free survival (PFS) and overall survival (OS). A total of 161 patients, 94 men and 67 women, were included in this study. Median age was 60 years. The majority of patients (79%) had stage IV disease, of which 60 patients (37%) had a KRAS mutation. Patients with a KRAS mutation had a similar response to treatment as patients with KRAS wild-type (wt) (p = 0.77). Median PFS in KRAS-mutated patients was 4.0 months versus 4.5 months in KRAS wt patients (hazard ratio = 1.3; [95% confidence interval, 0.9-1.8]; p = 0.16). Median OS in patients with KRAS mutation was 7.0 months versus 9.3 months in patients with KRAS wt (hazard ratio = 1.2; [95% confidence interval, 0.9-1.7]; p = 0.25). Type of KRAS mutation had no influence on response or outcome. On the basis of our multicenter data presented here, we conclude that KRAS mutation is not predictive for worse response to chemotherapy, PFS, and OS in advanced NSCLC patients treated with platinum-based chemotherapy in first-line setting.

KRAS Mutations Predict Sensitivity to Pemetrexed-Based Chemotherapy

SUMMARY Background:KRAS mutations, the most common oncogenic drivers in non-small-cell lung cancer, are found in at least a quarter of unselected cases. While data regarding the predictive nature of these aberrations has focused largely on targeted therapy, little is understood about the role of KRAS mutations in predicting sensitivity to cytotoxic chemotherapy. Aim: To evaluate clinical outcomes of patients with advanced adenocarcinoma of the lung harboring KRAS mutations treated with pemetrexed-based chemotherapy. Materials & methods: We performed a retrospective review of patients with advanced, KRAS-mutant and EGFR-wild-type (KRAS+/EGFR-) tumors receiving first-line chemotherapy containing pemetrexed and a platinum agent with or without bevacizumab. A second cohort of patients with KRAS- and EGFR-wild-type tumors (KRAS-/EGFR-) treated with a similar regimen was identified for comparison. Objective response rate (ORR) and progression-free survival (PFS) were compared between the cohorts. Results: Sixteen patients with KRAS+/EGFR- tumors and 19 with KRAS-/EGFR- tumors were identified. No significant differences in clinical characteristics between the two groups were noted, including age, gender, performance status, smoking or presence of brain metastases. Treatments did not differ statistically between cohorts in terms of cisplatin use, bevacizumab use, mean number of induction cycles or the use of either pemetrexed or pemetrexed–bevacizumab maintenance. ORR was better in the KRAS mutant tumors (56 vs 36%; p = 0.30), but did not reach statistical significance. PFS was longer in the KRAS+/EGFR- cohort (10.3 vs 5.7 months; p = 0.03). Conclusion: In this small retrospective series of patients treated with pemetrexed-containing chemotherapy, KRAS mutations were associated with a significantly longer PFS and a nonsignificant higher ORR.

Pathologic response, KRAS status, and bevacizumab: The Bermuda triangle for outcome prediction after hepatic colorectal cancer metastases (HCRM) resection.

e14716 Background: Clinicopathologic factors are insufficient to stratify prognosis after HCRM resection. The identification of prognostic biomarkers is an unmet clinical need. Even if the prognostic role of KRAS mutations in the metastatic setting is controversial, recent data hypothesized a correlation to worse outcome after HCRM resections. This analysis evaluated the correlation between KRAS mutation, pathological response and outcome. Methods: Fifty-eight pts with HCRM were resected at National Cancer Institute of Milan from 2007 to 2012 following bevacizumab (Bev) (n=30) or cetuximab (Cmab) (n=28) based neoadjuvant regimens. Tumor regression grade (TRG) was classified from TRG 1 for pathological complete response (pCR), to TRG5 for no response; TRG 1-3 for response; TRG 4-5 for scarce/no response. KRAS exons 2 to 4 were sequenced by direct PCR. Results: KRAS missing in 3 pts (1 Bev/2 Cmab), mutated in 23 (42%) vs wild-type in 32 (58%), mutated in 18 (62%) of Bev group vs 5 (19%) of Cmab. Mean TRG: 2.9 (2.2-4) in Bev vs 3.8 (3-5) in Cmab group (p=0.04 at Kruskal-Wallis test). Pathological response higher for Bev vs Cmab (70% vs 39%; p=0.037 at Chi-square test). Bev also increased pCRs (20% vs 0%, p=0.024 at Fisher’s test). Pathological response higher for KRAS mutant vs wild-type (70% vs 41%; p=0.003 at Chi-square test). At log-rank test, DFS significantly shorter for KRAS mutated vs wild-type (7.6 vs 14.6 months; p=0.05), and for TRG4-5 vs TRG1-3 (8.1 vs 15.3 months; p=0.02), while no difference observed according to treatment. OS data are not mature. Multivariable Cox model for DFS shown in the Table. Conclusions: After Bev-based neoadjuvant treatment, patients with KRAS mutated HCRM and without good pathological response may have the worst outcome after curative resection. [Table: see text]

The impact of KRAS mutations on VEGF-A production and tumour vascular network

BackgroundThe malignant potential of tumour cells may be influenced by the molecular nature of KRAS mutations being codon 13 mutations less aggressive than codon 12 ones. Their metabolic profile is also different, with an increased anaerobic glycolytic metabolism in cells harbouring codon 12 KRAS mutations compared with cells containing codon 13 mutations. We hypothesized that this distinct metabolic behaviour could be associated with different HIF-1α expression and a distinct angiogenic profile.MethodsCodon13 KRAS mutation (ASP13) or codon12 KRAS mutation (CYS12) NIH3T3 transfectants were analyzed in vitro and in vivo. Expression of HIF-1α, and VEGF-A was studied at RNA and protein levels. Regulation of VEGF-A promoter activity was assessed by means of luciferase assays using different plasmid constructs. Vascular network was assessed in tumors growing after subcutaneous inoculation. Non parametric statistics were used for analysis of results.ResultsOur results show that in normoxic conditions ASP13 transfectants exhibited less HIF-1α protein levels and activity than CYS12. In contrast, codon 13 transfectants exhibited higher VEGF-A mRNA and protein levels and enhanced VEGF-A promoter activity. These differences were due to a differential activation of Sp1/AP2 transcription elements of the VEGF-A promoter associated with increased ERKs signalling in ASP13 transfectants. Subcutaneous CYS12 tumours expressed less VEGF-A and showed a higher microvessel density (MVD) than ASP13 tumours. In contrast, prominent vessels were only observed in the latter.ConclusionSubtle changes in the molecular nature of KRAS oncogene activating mutations occurring in tumour cells have a major impact on the vascular strategy devised providing with new insights on the role of KRAS mutations on angiogenesis.

Role of KRAS mutations in the carcinogenesis of mucinous tumors of appendiceal origin with pseudomyxoma peritonei (PMP).

202 Background: Codon 12 KRAS and BRAF mutations may have a role in the mucinous differentiation pathway in colorectal cancer (Bazan V et al, Ann Oncol 2002; Tran et al, Cancer 2011). Elucidating the molecular mechanisms driving this disease is a priority for PMP, with the goal of identifying new markers and therapeutic targets needed to improve disease management. Due to the fact that neoplastic cells may be deceptively bland and sparse histologically within an abundant mucinous background, the adoption of high-sensitivity gene sequencing techniques may be extremely helpful. Methods: Mucinous tumors from 10 PMP cases of appendiceal origin treated in a multidisciplinary team at the National Cancer Institute of Milan were histologically classified according to Bradley classification. Following microdissection and DNA extraction, mutational analysis of KRAS exon 2-4 and BRAF exon 15 were performed by means of PCR, while KRAS exon 2 status was further confirmed through a specific mutant enriched PCR, shown to be a more sensitive approach in colorectal cancer (Molinari et al, Clin Cancer Res 2011). Results: Histological classification was low-grade in 6 and high-grade in 4 tumors. Codon 12 KRAS mutations were detected in 5/10 cases (50%). In the remaining 5 cases: sequencing of exon 4 lead to identification of a first-described A146V mutation in 1 case; with mutant enriched technique, we identified 3 additional codon 12 mutated cases. Due to use of high sensibility techniques and gene sequencing outside hotspot regions, we were able to identify KRAS mutations in 9/10 (90%) specimens. No BRAF exon 15 mutation was detected. Conclusions: The prognostic role of KRAS mutation in PMP patients is under investigation on a larger data-set of National Cancer Institute of Milan and will be presented at the Meeting. However, these preliminary data suggest a major role of KRAS in the carcinogenesis of mucinous tumors of appendiceal origin with PMP.

The dominant role of G12C over other KRAS mutation types in the negative prediction of efficacy of epidermal growth factor receptor tyrosine kinase inhibitors in non–small cell lung cancer

The role of KRAS mutations in molecular targeted therapy by epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer (NSCLC) has not been fully understood. The present investigation is aimed at an elucidation of the role of specific KRAS mutation types in predicting outcomes of patients with advanced NSCLC receiving EGFR-TKI therapy. Initially, 448 NSCLC patients were tested for the presence of KRAS mutations, to obtain frequencies of specific KRAS mutation types. Subsequently, the clinical outcome of treatment was evaluated in a subgroup of 38 KRAS-positive patients receiving EGFR-TKI therapy. KRAS mutations were detected in 69 of 448 patients (15.4%), mostly in smokers (17.86% vs. 5.8%, P = 0.0048), and appeared more frequently in adenocarcinomas than in squamous cell NSCLC or NSCLC that is not otherwise specified (21% vs. 6.99% vs. 4.4%, P = 0.0004). The most frequent type of KRAS mutation was G12C. The progression-free survival (PFS) was doubled in a group of non-G12C patients compared with that of the G12C group (9.0 wk vs. 4.3 wk, P = 0.009). The overall survival (OS) was not significantly different between non-G12C and G12C groups (12.1 wk vs. 9.3 wk, P = 0.068). The G12C KRAS mutation is a strong negative predictor for EGFR-TKI treatment, whereas other KRAS mutation types have not negatively predicted treatment efficacy compared with that for the wild-type KRAS genotype.

Survival outcome segregated by KRAS mutation status in newly diagnosed stage IV non-small cell lung cancer (NSCLC) patients (pts) treated with first-line chemotherapy.

7595 Background: KRAS mutations (MT) form a distinct subset of NSCLC, generally considered to have poor prognosis. Although KRAS MT is a well-establised prognostic and predictive marker in colorectal cancer, its role in NSCLC remains ambiguous. Pts with KRAS MT NSCLC do not respond well to epidermal growth factor receptor (EGFR) directed tyrosine kinase inhibitor therapy, but little is known about the ability of KRAS MT to predict outcome after first-line chemotherapy in newly diagnosed advanced or recurrent NSCLC. Methods: We analyzed outcomes of consecutive pts with newly identified Stage IV non- squamous NSCLC treated at University of Pennsylvania (Penn) between 05/2008 and 7/2010 and then compared survival based on KRAS status [MT vs wild type (WT)] using chi square, Kaplan-Meier methods, and Cox regression models. Results: Of 106 consecutive new pts with Stage IV non squamous NSCLC treated at Penn, 49 (46%) underwent molecular analysis for KRAS MT. Fifteen (34%) were KRAS MT. Of 34 KRAS WT pts, 6 were positive for EGFR MT. The median age of all 49 pts was 61 years; 83% were Caucasian, 45% male and 60% had a >10 pack year smoking history. Median duration of follow up is 16.4 mos. Majority of pts (92%) had adenocarcinoma histology. Most pts (88%) had ECOG PS 0-1 at presentation. Forty three pts received first line platinum-based combination chemotherapy (platinum and pemetrexed in 31 pts). KRAS MT was associated with smoking (p=0.04), but not with gender or age. Overall survival (OS) of pts with KRAS MT was similar to KRAS WT pts [median OS 15.6 vs. 19.0 mos; HR 1.24 (95% CI 0.57-2.67)]. Univariate analyses demonstrated superior OS among women compared to men (HR 0.40, 95% CI 0.20-0.85) in the entire pt cohort. Conclusions: In our population of stage IV non squamous NSCLC, pts with KRAS MT had similar OS to those with KRAS WT tumors. OS was slightly higher in KRAS WT pts, but this may have been confounded by the inclusion of 6 EGFR MT pts in this cohort. The potential prognostic or predictive role of KRAS MT in NSCLC pts undergoing chemotherapy requires further prospective study.

KRAS mutation as a prognostic factor in patients undergoing hepatic resection for metastatic colorectal cancer.

444 Background: It is well known that KRAS mutations limit the efficacy of anti-EGFR therapy in patients with metastatic colorectal cancer (mCRC). However the role of KRAS mutations in patients who undergo a curative liver resection for mCRC is less clear. The purpose of our study was to evaluate the relationship between KRAS mutation status and survival in this patient population. Methods: We examined an IRB approved tissue repository and retrospective database of 129 patients from 1998-2010 who underwent curative liver resection for mCRC. Tumors were sequenced for KRAS codons 12, 13, and 61 mutations using pyrosequencing. Overall survival (OS) and disease-free survival (DFS) were analyzed using the Kaplan-Meier method and compared using the log-rank test. Multivariate analysis was performed using the Cox proportional hazards regression method. Results: The median follow-up for our cohort was 20.4mo (0.4-112). Mean age was 61.4±12.3. Prior to surgical resection 55 (43%) patients received chemotherapy. 35 (27%) tumors were KRAS mutant (mt), 83 (64%) were wild-type (wt), and 11 (9%) were not characterized. Median OS for KRAS wt patients was 40.3mo vs. 27.1mo for KRAS mt patients (p=0.046). Median DFS for KRAS wt was 13.6mo vs. 7.7mo for KRAS mt patients (p=0.037). 8 patients received cetuximab post–operatively. Cetuximab status was unknown in 50 patients. When we excluded those treated with cetuximab, the median OS was 40mo for KRAS wt vs. 25mo for KRAS mt patients (p=0.007). There were no differences in OS or DFS in patients who received cetuximab (p=0.7). In a multivariable model with pre-operative chemotherapy (p=0.2), extent of resection (p=0.053), and cetuximab therapy (p=0.7), the presence of KRAS mutation was independently associated with poor prognosis (HR=2.7 [1.3-5.5]). Conclusions: In patients undergoing curative liver resection for mCRC, KRAS mutation status is independently predictive of a worse outcome regardless of cetuximab therapy. KRAS status may be associated with more aggressive tumor biology. Our data supports the critical need to define KRAS mutation status and to develop therapies against KRAS and its downstream effectors.

Abstract A31: Predictive and prognostic value of KRAS mutations in advanced non-small cell lung cancer (NSCLC) patients treated with chemotherapy

Abstract Introduction: K-Ras mutation is thought to be related with poor outcome of NSCLC patients with an advanced stage of disease. The role of K-Ras mutation as a predictor of response for these patients treated only with chemotherapy is poorly understood. Patients and methods: From a retrospective database from 2 university hospitals all patients with advanced stage, nonsquamous, NSCLC treated with palliative platinum containing chemotherapy were selected. Patients were included when archive tumour tissue was available for DNA extraction. High resolution melting followed by PCR sequencing was performed for KRAS exon1 and 2. Response to treatment was assessed by RECIST. The databases were matched by treatment. Results: A total of 179 patients were included in this study. All patients were treated with chemotherapy and were no candidate for treatment with curative intent. There were 59 patients with a K-Ras mutation (32.9%). There was no significant difference in basic characteristics between the group with a K-Ras mutation and the group with K-Ras wild-type. Mean age 59 years (range 32–83 years), 108 males and 71 females. ECOG performance score 0/1/2/3 73/77/13/2. Thirty patients with stage IIIb disease, 149 patients with stage IV disease. Progression as best response to treatment was reported in 21/59 patients with a K-ras mutation (35.6%) and 34/120 patients (28.3%) with a K-Ras wild type, this was not significant (p=0.611). The median progression free survival (PFS) in the group with a K-Ras mutation was 4.1 months (95% CI 3.12–5.0 months) compared to 5.4 months (95% CI 4.4–6.4 months) in patients with K-Ras wild type (p=0.202). The overall survival (OS) in the group with a K-Ras mutation, was 8.3 months (95% CI 5.2–11.4 months) compared to 12.5 months (95% CI 10.2–14–7 months) in patients with K-Ras wild type (p=0.037). Conclusion: In our series K-Ras mutation was not predictive for response to platinum containing chemotherapy in patients with advanced NSCLC. K-Ras mutational status was prognostic for overall survival.

Use of KRAS codon 13 mutations to predict response to neoadjuvant chemoradiation therapy in patients with rectal adenocarcinoma.

453 Background: The predictive role of KRAS mutation in therapeutic management of metastatic colorectal cancer has been much investigated. However, the association between KRAS mutations and rectal cancer response to neoadjuvant chemoradiation therapy (CRT) remains unclear. Our objectives were to determine the incidence of KRAS mutations in patients with rectal cancer and identify potential correlations with response to CRT. Methods: Patients with Stage II-III rectal cancer (n=148) from a multicenter prospective clinical trial were assessed. DNA was extracted from pretreatment tumor biopsies; and genotyping of KRAS was completed by PCR and direct sequencing. All patients underwent pre-operative CRT followed by surgery; and treatment response was evaluated by a pathologist. Surgical specimens without evidence of residual disease were deemed to have a pathologic complete response (pCR). Results: Overall, 60 of 148 (40.5%) patients had KRAS mutation. Breakdown of the different KRAS mutations revealed that 40 (66.7%) mutations occurred in codon 12, 12 (20.0%) in codon 13, 5 (8.3%) in codon 61, and 3 (5.0%) in other locations. When examining the relationship between KRAS and CRT response, we observed that detection of any KRAS mutation was associated with a decreased rate of pCR compared to wild-type KRAS (13.3% vs. 33.0%, respectively; p=0.007). More specifically, patients with KRAS codon 13 mutations did not respond to CRT compared to non-codon 13 mutations (p=0.037). In contrast, the detection of codon 12 or codon 61 mutations was not associated with response to CRT ( Table ). Conclusions: Patients with KRAS mutation have lower response rates to CRT compared to patients with wild-type KRAS. However, our results indicate that this association does not apply to all KRAS mutations, rather to KRAS codon 13 mutation alone. Thus, these data are the first to show that patients with KRAS codon 13 mutations may not derive pCR from neoadjuvant CRT. [Table: see text]

The role of specific KRAS mutation types in response to treatment by EGFR inhibitors.

e18006 Background: KRAS mutations can be found in 15 to 25% of lung cancers, frequently in adenocarcinomas and their presence is associated with smoking. The role of KRAS mutations in biological targeted therapy by EGFR inhibitors is ambiguous. While some reports clearly assigned mutated KRAS as negative prognostic factor and negative predictor, others did not confirm such notion. In our work we aimed to elucidate the role of specific type of KRAS mutation in outcome of patients with advanced NSCLC threated with EGFR-TKI therapy. Methods: 443 patients with NSCLC were examined. 38 patients, threated with erlotinib or gefitinib in maintenance setting, were further evaluated. 30 patients were suffering from adenocarcinoma, 7 patients had squamous cell carcinoma including 1 patient with poorly diferentiated carcinoma. 37 patients were smokers and only 1 patient was never smoker. Statistical significance was scrutinized by a Log rank test at a 95% confidence level. Results: KRAS mutation was detected in 66 patients. Glycine to cystein substitution at codon 12 [G12C] was the most frequent type of KRAS mutation, detected in 24 patients. Outcome of patients with G12C [n=24] and patients with other specific type of mutation [nonG12C] [n=14] was compared. Median of TTP in the G12C group was 4,3 weeks in comparison with 9,0 weeks in the nonG12C group [p 0.009]. Median of TTP among patients with adenocarcinoma in the G12C group was 4,1 weeks in comparison with 9,0 weeks in the nonG12C group [p 0.007]. Median of OS in the G12C group was 9,3 weeks in comparison with 12,1 weeks in the nonG12C group [p 0.068], median of OS among patients with adenocarcinoma in the G12C group was 9,3 weeks in comparison with 10,6 weeks in the nonG12C group [p 0.095]. Analysis of OS was influenced by different oncological threatment after EGFR-TKI, different quality of basic supportive care and higher incidence of brain matestasis in the nonG12C group. Conclusions: G12C KRAS mutation is a strong negative predictor for EGFR-TKI threatment. Other specific types of KRAS mutation didn’t prove such a negative predictive value and TTP was comparable to patients bearing wild type KRAS gene.

BRAF and KRAS mutations in penile cancer and their correlation with clinical features.

221 Background: Penile cancer is a rare disease in developed countries. While surgery may be curative for patients with localized disease, for metastatic patients systemic chemotherapy may offer palliation with usually short-lived responses. Thus, new options in this setting are needed. Retrospective series have reported EGFR overexpression in more than 90% of the cases and also interesting results of EGFR directed therapies in these patients have been comunicated. The role of KRAS status or other molecular markers as prognostic or predictive factors remains unclear. The aim of this study was to determine the prevalence of BRAF and KRAS somatic mutations in penile cancer and their correlation with clinicopathologic features. Methods: We analyzed 28 samples collected from de archives of the Pathology Department at our institution from 1996 to 2009. The DNAs were extracted from FFPE blocks by Biorobot EZ1 following the manufacturer protocol of the EZ1-DNA Tissue kit (Qiagen). KRAS and BRAF mutations were amplified with specific primers, and sequenced by Sanger with Bigdye terminator v3.1 Cycle Sequencing Kit. Medical records were reviewed for clinical data. Results: No BRAF mutations were found, but we identified somatic missense mutations in the KRAS gene (all activating G12D mutations) in 6/27 samples (22%, one not evaluable). Median age at diagnosis (73 vs. 71), grade and histologic subtype did not differ between wt and mutated (mt) patients. There was a trend toward a more advanced stage at diagnosis in mt versus wt : 33 versus 47% stage I, 16 versus 9% stage II and 50 versus 38% stage III respectively. 2/6 mt patients died (due to other causes) as did 5/21 wt patients (3 of them because of disease progression). Conclusions: BRAF mutations seem not involved in the EGFR pathway in penile carcinomas. The prevalence of KRAS mutations was unexpectedly high in our series and mt patients tended to be diagnosed at a more advanced stage. Unfortunately, no correlation was found with other clinicopathologic features, including overall survival in our small series. These results suggest a role of KRAS mutation in the development of these carcinomas and support the importance to determine KRAS status in patients to be treated with anti-EGFR based therapies. No significant financial relationships to disclose.

EGFR, TS, and ERCC1 expression in penile squamous cancer (PSC).

219 Background: PSC is an aggressive disease with devastating consequences. While near-universal EGFR overexpression has been documented, little is known about its clinical implications, and the potential role of KRAS mutations has not been described. In other tumor types, ERCC1 and TS expression are associated with response to platinum and 5FU chemotherapy, but have not yet been evaluated in PSC. Methods: After IRB approval, 28 PSC patients treated at LAC-USC were identified with tumor specimens available. Testing for EGFR, TS, and ERCC1 expression relative to internal standard gene was performed by real-time RT-PCR and correlated with clinical features. Results: The median age was 45 (30-78). There were 2 Black, 1 Asian, 1 White, and 15 Hispanic men; 9 had unspecified race. T stages included 4 Tis, 6 T1, 17 T2, and 9 T3; 11 men had lymph node (LN) involvement. No KRAS mutations were identified. EGFR had the highest relative expression (median 4.65, range 1.6-44.2), followed by TS (median 1.69, range 0.49-4.69); ERCC1 overexpression was rare (median 0.54, range 0.21-1.29). Higher EGFR expression was significantly associated with poor differentiation (median 12.5 compared to 3.6 for moderate/well differentiated tumors) on continuous (p=0.03 by Mann Whitney) and cut-point analysis using >7 (two- sided p=0.03 by Fisher's exact test) but did not correlate with stage. Stage > T2 showed a trend toward higher risk of LN involvement (p=0.06 by chi square). There was no correlation between differentiation and stage, and no significant correlation for ERCC1 or TS with grade or stage. Conclusions: EGFR overexpression is common in PSC and correlates with tumor grade but not stage, suggesting it may be important for disease progression. The absence of KRAS mutations may portend responsiveness to EGFR- targeted therapy based on experience in other tumors. Low ERCC1 as an association with platinum response will be explored in an expanded cohort. No significant financial relationships to disclose.

Phase II trial of cetuximab plus irinotecan for FOLFOX and FOLFIRI-refractory patients with EGFR-positive advanced and/or metastatic colorectal cancer: Evaluation of the efficacy and safety based on KRAS mutation status (T- CORE0801).

573 Background: Activating mutation of the KRAS gene is a predictive biomarker for loss of efficacy to anti-EGFR antibody therapy. However, this was mainly established by the evidences of Caucasian studies. Then, this prospective study investigated the role of KRAS mutations on efficacy and safety to cetuximab plus irinotecan in Japanese patients with metastatic colorectal cancer (mCRC). Methods: We conducted a prospective study to analyze objective response to cetuximab plus irinotecan in molecularly defined KRAS wild-type (WT) or mutant subgroups of chemotherapy-refractory mCRC. KRAS mutations were detected by direct sequence on DNA from formalin-fixed, paraffin-embedded tissue of patients treated in 11 centers in Japan. Additional EGFR related genes such as BRAF, PIK3CA etc. and antibody-dependent cellular cytotoxicity related polymorphism in FCγRIIa and RIIIa genes were also examined. Results: Forty-three patients were enrolled. KRAS mutations were found in 31.7% of 41 eligible patients. Response rate (RR) to cetuximab plus irinotecan, the primary endpoint of the study, was 17.9% and 0% for the patients with tumor harboring WT and mutant KRAS, respectively. No significant differences in toxicity were observed between the KRAS WT and mutant groups. Detail statistical analyses are ongoing. Conclusions: We confirmed that KRAS status is a useful predictive maker for the efficacy to cetuximab plus irinotecan therapy in Japanese mCRC patients, even though the response rate in the KRAS WT group was lower than expected. [Table: see text]

The role of kras mutations and MSI status in diagnosis of colorectal cancer.

The aim of the current investigation was to examine the profile of Kras mutations accompanied with MSI (microsattelite instability) status in polyps and colorectal carcinoma tissues in an Iranian population. Kras mutations in colorectal cancer cause resistance to anti-Epidermal Growth Factor Receptor (EGFR). So it can be considered as a true indicator of EGFR pathway activation status. Kras mutations can be detected in approximately 30% to 40% of all patients with colorectal cancer. The most hot spot of the gene is located in exons 2 and 3. In this study we examined exons 2 and 3 Kras gene using polymerase chain reactions and subsequent sequencing of the exons in 95 patients with sporadic colorectal cancer including 48 tumors and 47 polyps. This study was performed using biopsy samples from the patients. We sequenced the Kras gene in a panel of human colorectal tumors and polyps in addition to detecting MSI status using fluorescent technique. We could detect 6 mutations in tumors including 5 mutations in codon 12 and one mutation in codon 13. Moreover, in polyps 2 mutations were determined in codon 13 and one in codon 12. Microsatellite instability assay revealed the presence of 5 and 6 MSI in tumors and polyps, respectively. Among the MSI mononucleotide markers, NR-21 marker demonstrated the most frequency (60%) in the both groups. Our findings showed that probably the profile of mutations in tumors is not entirely compatible with the pattern of mutations in polyps. However, just one of the mutations, Gly12Asp, was similar in both groups.