KRAS Mutations In Non-small Cell Lung Cancer Research Articles

Prognostic and Predictive Value of K-RAS Mutations in Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is a heterogeneous disease, caused by the presence of different clinically relevant molecular subtypes. Genetic mutations are emerging as potential biomarkers of response and treatment selection in patients with NSCLC. Over the past few years, activating mutations of epidermal growth factor receptor (EGFR) have been recognized as the most important predictor of response to EGFR tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib and also as a favourable prognostic factor. The RAS genes, including H-RAS, K-RAS and N-RAS, encode a family of proteins regulating cell growth, differentiation and apoptosis. Mutations in the K-RAS gene, mainly in codons 12 and 13, have been found in 20-30% of NSCLC tumor samples and occur most commonly, but not exclusively, in adenocarcinoma histology and in heavy smokers. In NSCLC, the presence of K-RAS mutations has generally been considered to be associated with worse prognosis and resistance to systemic therapy in the adjuvant as well as the metastatic setting. In early stage NSCLC, the prognostic role of K-RAS mutations has been evaluated in several studies without definitive conclusion. On the other hand, in advanced NSCLC, the presence of K-RAS mutations identifies a subgroup of patients who do not respond to EGFR-TKI therapy but, at the same time, a positive survival effect from EGFR-TKIs cannot be excluded in these patients. Similarly, K-RAS mutational status does not predict benefit from the anti-EGFR monoclonal antibody cetuximab, highlighting the biological difference between lung cancer and colorectal cancer. As a result of the lack of conclusive data, K-RAS mutations do not represent a validated biomarker for the negative selection of patients who are candidates for anti-EGFR therapy. The aim of this article is to review and discuss the data on the prognostic and predictive value of K-RAS mutations in NSCLC.

Prognostic and predictive effects of KRAS mutation subtype in completely resected non-small cell lung cancer (NSCLC): A LACE-bio study.

7007 Background: We reported previously that KRAS is weakly prognostic and not significantly predictive of benefit from adjuvant chemotherapy (ACT) in NSCLC (Tsao et al. Proc ESMO 2012, Abst 4217). In colorectal cancer (CRC), KRAS mutation predicts resistance to EGFR monoclonal antibodies, but recent reports suggest that this may not be true for all mutation subtypes (De Roock et al. JAMA 2010). Smoking-related KRAS mutations in NSCLC differ from those of CRC. To explore the influence of KRAS mutation subtype, we undertook an analysis of KRAS subtype in LACE-Bio. Methods: KRAS mutation was determined in blinded fashion in 3 laboratories by direct sequencing. Exploratory analyses were performed to identify relationships between mutation status and subtype, overall (OS) and disease-free survival (DFS) using a Cox model stratified by trial and adjusted for covariates. Results: KRAS subtype was available in 1,532 patients (756 observation [OBS], 776 ACT). There were 300 mutations (275 codon 12, 24 codon 13, 1 codon 14). In the OBS arm, there was no difference in prognosis for OS for codon 12 (Hazard Ratio [HR] mutation v wild-type [WT] KRAS 1.04, CI .77-1.4) or codon 13 (HR 1.01, CI 0.47-2.17) mutations. A trend for benefit from ACT was observed in WT (HR ACT v OBS 0.89 CI 0.76-1.04, p=0.15) but not in patients with codon 12 mutations (HR 0.95, CI .67-1.35, p=0.77). In patients with codon 13 mutations, chemotherapy was deleterious (HR 5.78, CI 2.06-16.2, p<0.001), test for equality among 3 HRs p=0.002. Results were similar for DFS. Among codon 12 mutations, there was no prognostic effect based on specific amino acid substitution. Patients with G12A or G12R mutations appeared to derive greater benefit from ACT (HR 0.66 p=0.48) compared to those with G12C or G12V (HR 0.94 p=0.77) or G12D or G12S (HR 1.39 p=0.48) or WT, but the differences were not significant (comparison of 4 HRs p=0.76). Conclusions: In this study, patients with KRAS codon 13 mutations had significantly poorer outcomes with ACT. These results require further confirmation and should be interpreted with caution in view of the small number of patients with codon 13 mutations. Supported by unrestricted grants from Sanofi Aventis and LNCC.

K-Ras Mutations in Non-Small-Cell Lung Cancer: Prognostic and Predictive Value.

Non-small-cell lung cancer (NSCLC) is a heterogeneous disease due to the presence of different clinically relevant molecular subtypes. Until today, several biological events have been identified in lung adenocarcinoma, including epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) translocations, offering new hopes to patients with metastatic disease. Unfortunately, in approximately 50% of adenocarcinoma and for those harbouring K-RAS mutations, the most frequent mutation in Caucasian lung adenocarcinoma, so far no specific drug demonstrated efficacy. The rat sarcoma (RAS) genes, including H-RAS, K-RAS, and N-RAS, encode a family of proteins regulating cell growth, differentiation, and apoptosis. K-RAS mutations are present in 20–30% of NSCLC and occur most commonly, but not exclusively, in adenocarcinoma histology and life-long smokers. Although in colorectal cancer patients K-RAS mutations represent a validated negative predictive biomarker for treatment with anti-EGFR monoclonal antibodies, their role in selecting specific treatment for NSCLC patients remains undefined. Aim of the present paper is to critically analyze the prognostic and predictive value of K-RAS mutations in NSCLC.

Abstract 2138: Tumorigenic and migratory potential of Ral GTPases in non-small cell lung cancers

Abstract The Ral GTPase family, consisting of the Ral A and B isoforms contributes to tumor formation, invasion and metastasis, however their role in non-small cell lung cancer (NSCLC) is yet to be validated. Recently, we investigated the role of Ral GTPases in NSCLC by in vitro expression, colony formation and migration assay, in vivo tumor formation experiments, and analysis of microarray data from NSCLC patients. In vitro, Ral A and Ral B was expressed in all NSCLC cell lines studied (14) to varying levels. Increased expression of Ral A or Ral B was more frequent in Ras mutant cell lines (Ral A elevated in 2/8 cell lines with mutant KRas vs. 0/6 cell lines with WT KRas, Ral B elevated in 5/8 cell lines with mutant KRas vs. 2/6 WT KRas). Soft agar experiments with transient knockdown of Ral A, Ral B and Ral A+B in these cell lines demonstrated significant decrease (p<0.05) in colony formation. Dual knockdown of Ral A and B had a 2 to 3 fold decrease (p<0.05) in NSCLC cell motility in wound healing assays. In vivo, knockdown of Ral GTPases resulted in reduced subcutaneous tumor growth (p<0.05) in mice injected with the knockdown cells. Microarray data from NSCLC patients was analyzed to study the correlation between Ral A and B expression with overall patient survival. High Ral A expression was associated with poor patient survival in these microarray datasets (p<0.05). The above observations demonstrate that Ral GTPases play a role in lung cancer tumorigenesis and migration. In the Ras signaling cascade, Ral GTPases are downstream of Ras along with PI3K and MAPK signaling pathways. KRas mutations in NSCLC carry a poor patient prognosis. Based on our observations, we posit that Ral GTPases can be a valid target for drug development against KRas mutated lung cancers along with PI3K and MEK inhibitors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2138. doi:1538-7445.AM2012-2138

EGFR and KRAS mutations in lung carcinomas in the Dutch population: increased EGFR mutation frequency in malignant pleural effusion of lung adenocarcinoma

BackgroundFrequencies of EGFR and KRAS mutations in non-small cell lung cancer (NSCLC) have predominantly been determined in East Asian and North American populations, showing large differences between these populations. The aim of the present study was to determine the frequency of EGFR and KRAS mutations in NSCLC in the West European Dutch population in primary carcinomas and different metastatic locations.Methods EGFR (exons 19, 20 and 21) and KRAS (exons 2 and 3) mutation test results of NSCLC samples of patients in 13 hospitals were collected. The tests were performed on paraffin-embedded tissue or cytological material of primary and metastatic lung carcinomas.Results EGFR mutations were detected in 71/778 (9.1 %) tested patients; in 66/620 (10.6 %) adenocarcinomas. EGFR mutations were significantly more often detected in female than in male patients (13.4 % vs. 5.5 %, p < 0.001). KRAS mutations were found in 277 out of 832 (33.3 %) tested patients; in 244/662 (36.9 %) adenocarcinomas. A significantly increased frequency of EGFR mutations was observed in patients with malignant pleural/pericardial effusions (26.5 %; odds ratio (OR) 2.80, 95 % confidence interval (CI) 1.22–6.41), whereas the frequency of KRAS mutations was significantly decreased (18.8 %; OR 0.35, 95 % CI 0.14–0.86).ConclusionsIn the investigated Dutch cohort, patients with malignant pleural/pericardial effusion of lung adenocarcinoma have an increased frequency of EGFR mutations. The overall frequency of EGFR mutations in lung adenocarcinomas in this West European population is within the frequency range of North American and South European populations, whereas KRAS mutation frequency is higher than in any population described to date.

KRAS mutations (MTs) in non-small cell lung cancer (NSCLC) versus colorectal cancer (CRC): Implications for cetuximab therapy.

10529 Background: KRAS MTs have been associated with a diversity of biologic functions, and have both prognostic and predictive consequences in NSCLC and CRC. Little data exist comparing the specifics of KRAS MTs in the two cancers. In CRC, benefit from the cetuximab is mainly limited to patients whose tumors are KRAS wild-type (WT). However, recent studies show no such predictive value in NSCLC. We hypothesized that the unique molecular biology and tobacco carcinogen-related etiology of NSCLC contribute to a divergence in KRAS MT type and EGFR-related dependency. Here, we compare KRAS and EGFR status in NSCLC versus (vs) CRC in the large Response Genetics (RGI) database. Methods: KRAS MTs were assessed in 2,693 specimens (838 CRC and 1165 NSCLC) using DNA from microdissected formalin fixed paraffin embedded tumor specimens. EGFR MTs were determined in 649 NSCLCs. A PCR approach with direct sequencing was used to detect 7 different base substitutions in KRAS and 28 EGFR MTs. Statistics: Fisher's Exact Test. Results: KRAS MTs were found in 39% of CRC and 23% of NSCLC specimens (p < 0.001). EGFR MTs were identified in 16% of NSCLCs. In 447 specimens with both assays, EGFR and KRAS MTs were largely exclusive; 4 specimens harbored both (p < 0.001). The ratio of base transversions to transitions was 3.27 in NSCLC versus 0.77 in CRC (p < 0.001). With regard to histology, in NSCLC KRAS MTs were observed in 28.7% (186/649) of adenocarcinomas vs 3.5% (7/198) of squamous cell carcinomas (p < 0.001). Tobacco carcinogenesis-associated G>T transversions (codon 12 GGT>TGT plus GGT>GTT) comprised 61% of KRAS MTs in NSCLC vs 39% in CRC (p < 0.001). The GGT>GAT transition was most prevalent in CRC at 33.3%. Conclusions: This analysis of the RGI database demonstrates differences between NSCLC vs CRC in both incidence and type of KRAS MTs. Increased frequencies of DNA KRAS transversions were seen in NSCLC, likely linked to tobacco exposure. Distinct MT patterns and biologic function may contribute to differences in predictive value for cetuximab therapy between NSCLC and CRC. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Response Genetics Amgen, AstraZeneca, Biodesix, Boehringer Ingelheim, Bristol-Myers Squibb, Genentech, Genoptix, GlaxoSmithKline, Lilly, Merck, Novartis, Pfizer, Response Genetics, sanofi-aventis Response Genetics DxS, Response Genetics Abbott Laboratories, Bristol-Myers Squibb, Genentech, Lilly, Merck, Novartis, OSI, Pfizer

EGFR and K-ras mutations as determinants of gefitinib sensitivity in non-small-cell lung cancer (NSCLC)

7078 Background: EGFR mutation is associated with response and prolonged survival in NSCLC patients treated with gefitinib. We have previously observed negative correlation of p-Erk and efficacy of gefitinib. K-ras mutation may constitutively activate p-Erk. Recently, HER2 mutation was found in NSCLC. We have investigated EGFR, HER2, and K-ras mutations in NSCLC treated with gefitinib. Methods: Advanced NSCLC patients (pt) received gefitinib 250mg/day. EGFR (exons 18, 19, 21, and 23), HER2 (exons 19 and 20), and K-ras (codons 12 and 13) mutations (mt) were identified by direct sequencing of PCR products of DNA extracted from archival paraffin embedded tissue. P-Erk and p-Akt expression was determined by immunohistochemistry (IHC). Baseline characteristics, mutational status, IHC data and efficacy of gefitinib were analyzed in respect to each other. Results: 59 pt were analyzed. 13 pt harbored EGFR mt and 8 pt harbored K-ras mt, whereas HER2 mt was found in none. EGFR mutation was significantly associated with response [response rate (RR) 61.5% in mt(+) vs.13.0% in mt(-), p=0.001], time-to-progression (TTP) [13.7 months (M) in mt(+) vs. 1.3 M in mt(-), p=0.001], and overall survival (OS) [not reached in mt(+) vs. 5.8 M in mt(-), p=0.001]. Among 8 pt with K-ras mt, 2 pt had stable disease (SD), 6 pt had progressive disease (PD), and no pt had response to gefitinib [RR 0% vs. 27.5% in K-ras mt (-), p=0.18]. No association was found between K-ras mt and TTP or OS. 2 pt concomitantly had EGFR and K-ras mt; 1 pt had SD and the other PD. RR in EGFR mt(+)/K-ras mt(-), EGFR mt(-)/K-ras mt(-), and K-ras mt(+) were 72.7%, 15.0%, and 0%, respectively (p<0.001). K-ras mutation was more frequently found in male (p=0.067), squamous cell carcinoma (p=0.095), and smokers (p=0.008). 6/7 pt with K-ras mt exhibited positive p-Erk expression [85.7% vs. 58.8% in K-ras mt (-), p=0.24]. Conclusion: These results support the assumption that K-ras mutation may have role in gefitinib resistance via activation of Ras/Raf/Erk pathway. Together with EGFR mutation, K-ras mutation may aid in patient selection for treatment with gefitinib in NSCLC. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration AstraZeneca

K-ras oncogene mutation as a prognostic marker in non-small cell lung cancer: a combined analysis of 881 cases.

The treatment of non-small cell lung cancer (NSCLC) remains unsatisfactory, with most patients succumbing to metastatic disease within 5 years of diagnosis. Improved selection of patients for aggressive adjuvant therapy may contribute to improved survival. Mutation of the k-ras oncogene is considered a potentially clinically useful prognostic biomarker for this purpose. This report presents the results of a meta-analysis performed to determine whether the existing data support such a role for k-ras mutations in NSCLC. Two year survival data derived from 881 NSCLC patients in eight published studies were analyzed using a general variance-based meta-analytical method employing confidence intervals. The outcome of interest was a summary relative risk (RR(s)) reflecting the risk of death at 2 years associated with k-ras mutation-positive versus k-ras mutation-negative disease. Prior to calculation of RR(s), analysis for heterogeneity showed Q to equal 15.52 (7 df, P = 0.03). This indicated heterogeneity across the analyzed studies in terms of their estimate of effect. Possible sources of heterogeneity were identified and included selection bias and various other sources of uncontrolled confounding. Although a RR(s) of 2.35 (95% CI = 1.61-3. 22) was found when all eight studies were combined (favoring a negative prognostic role for k-ras mutation), it is unclear whether the magnitude of the RR(s) would persist after adjusting for other well-established prognostic indicators (e.g. stage). The existing data suggest that k-ras mutation may be associated with shortened survival in NSCLC, although this finding awaits confirmation in well-designed multivariate analyses which adjust for the effect of known prognostic indicators.