Predictive Value Of KRAS Mutations Research Articles

Flashback Foreword: KRAS Is a Selection Marker for Panitumumab Benefit in Patients With Metastatic Colorectal Cancer

Article Tools FLASHBACK FOREWORD Article Tools OPTIONS & TOOLS Export Citation Track Citation Add To Favorites Rights & Permissions COMPANION ARTICLES JCO Flashback: Predictive Value of KRAS Mutations on the Outcomes of Panitumumab Monotherapy in Colorectal Cancer. June 14, 2023 Wild-Type KRAS Is Required for Panitumumab Efficacy in Patients With Metastatic Colorectal Cancer. June 14, 2023 ARTICLE CITATION DOI: 10.1200/JCO.23.00221 Journal of Clinical Oncology - published online before print June 14, 2023 PMID: 37315388 Flashback Foreword: KRAS Is a Selection Marker for Panitumumab Benefit in Patients With Metastatic Colorectal Cancer Andrew H. Ko, MD1,2xAndrew H. KoSearch for articles by this author Show More 1Associate Editor, Journal of Clinical Oncology, Alexandria, VA2University of California San Francisco Cancer Center, San Francisco, CA https://doi.org/10.1200/JCO.23.00221 First Page Full Text PDF Figures and Tables © 2023 by American Society of Clinical OncologyTHE TAKEAWAYIn 2008, Amado et al1 published a biomarker analysis demonstrating the negative predictive value of KRAS mutations for outcome of antiepidermal growth factor receptor therapy in patients with advanced colorectal cancer. These findings guide treatment decision making for colorectal cancer that continues up to the present time and also informed further discoveries relating to treatment resistance and approaches to monitoring for this disease.AUTHOR'S DISCLOSURES OF POTENTIAL CONFLICTS OF INTERESTFlashback Foreword: KRAS Is a Selection Marker for Panitumumab Benefit in Patients With Metastatic Colorectal CancerThe following represents disclosure information provided by the author of this manuscript. All relationships are considered compensated unless otherwise noted. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO's conflict of interest policy, please refer to www.asco.org/rwc or ascopubs.org/jco/authors/author-center.Open Payments is a public database containing information reported by companies about payments made to US-licensed physicians (Open Payments).Andrew H. KoThis author is an Associate Editor for Journal of Clinical Oncology. Journal policy recused the author from having any role in the peer review of this manuscript.Honoraria: Research to Practice, Clinical Care Options, Medscape, BioAscent, MJH Life Sciences, Gerson Lehrman GroupConsulting or Advisory Role: ERYTECH Pharma, Imugene, SynCoreBio, Roche/Genentech, Ipsen, Five Prime Therapeutics, Tyme, Turning Point Therapeutics, Signatera, Syros PharmaceuticalsSpeakers' Bureau: Clinical Care OptionsResearch Funding: Celgene (Inst), Merck (Inst), Genentech/Roche (Inst), Bristol Myers Squibb (Inst), AbGenomics International (Inst), Apexigen (Inst), Astellas Pharma (Inst), Leap Therapeutics (Inst), BioMed Valley Discoveries (Inst), CrystalGenomics (Inst)No other potential conflicts of interest were reported. Companion JCO Flashback: Predictive Value of KRAS Mutations on the Outcomes of Panitumumab Monotherapy in Colorectal Cancer Wild-Type KRAS Is Required for Panitumumab Efficacy in Patients With Metastatic Colorectal Cancer

Mutations matter: An observational study of the prognostic and predictive value of KRAS mutations in metastatic colorectal cancer.

About half of metastatic colorectal cancers (CRCs) harbor Rat Sarcoma (RAS) activating mutations as oncogenic driver, but the prognostic role of RAS mutations is not fully elucidated. Interestingly, specific hotspot mutations have been identified as potential candidates for novel targeted therapies in several malignancies as per G12C. This study aims at evaluating the association between KRAS hotspot mutations and patient characteristics, prognosis and response to antiangiogenic drugs. Data from RAS-mutated CRC patients referred to Careggi University Hospital, between January 2017 and April 2022 were retrospectively and prospectively collected. Tumor samples were assessed for RAS mutation status using MALDI-TOF Mass Spectrometry, Myriapod NGS-56G Onco Panel, or Myriapod NGS Cancer Panel DNA. Among 1047 patients with available RAS mutational status, 183 KRAS-mutated patients with advanced CRC had adequate data for clinicopathological and survival analysis. KRAS mutations occurred at codon 12 in 67.2% of cases, codon 13 in 23.5%, codon 61 in 2.2%, and other codons in 8.2%. G12C mutation was identified in 7.1% of patients and exon 4 mutations in 7.1%. KRAS G12D mutation, as compared to other mutations, was significantly associated with liver metastases (1-sided p=0.005) and male sex (1-sided p=0.039), KRAS G12C mutation with peritoneal metastases (1-sided p=0.035), KRAS G12V mutation with female sex (1-sided p=0.025) and no surgery for primary tumor (1-sided p=0.005). No associations were observed between specific KRAS variants and age, ECOG PS, site of primary tumor, pattern of recurrence for resected patients, and lung, distant lymph node, bone, or brain metastases.Overall survival (OS) was significantly longer in patients with KRAS exon 4 mutations than in those with other KRAS mutations (mOS 43.6 months vs 20.6 months; HR 0.45 [0.21-0.99], p=0.04). No difference in survival was observed for mutations at codon 12/13/61 (p=0.1). Treatment with bevacizumab (BV) increased significatively mPFS (p=0.036) and mOS (p=0.019) of the entire population with a substantial benefit in mOS for G12V mutation (p=0.031). Patterns of presentation and prognosis among patients with specific RAS hotspot mutations deserve to be extensively studied in large datasets, with a specific attention to the uncommon isoforms and the role of anti-angiogenic drugs.

Predictive value of KRAS mutation and excision repair cross-complementing 1 (ERCC1) protein overexpression in patients with colorectal cancer administered FOLFOX regimen

BackgroundRecent studies have reported that KRAS mutational status is correlated with ERCC1 expression level. The purpose of this study was to determine the clinical significance of the KRAS mutation and ERCC1 overexpression status as predictive factors for resistance against oxaliplatin-based treatment. MethodsWe retrospectively analyzed clinicopathologic features, KRAS mutation status, and ERCC1 overexpression status in 386 patients with colorectal cancer (CRC) who underwent curative-intent surgery. Of these patients, 84 were administered the FOLFOX regimen as a first-line or adjuvant treatment. Disease-free survival and overall survival in groups separated by KRAS and ERCC1 statuses were analyzed. ResultsWild-type KRAS and ERCC1 overexpression were observed in 25.5% of all patients. Among the 84 patients who were treated with the FOLFOX regimen, 73 patients were evaluated for KRAS and ERCC1 status. There were no significant differences in disease-free survival or overall survival in groups separated by KRAS mutation and ERCC1 expression status. Subgroup analysis of patients with wild-type KRAS showed that overall survival in the ERCC1 overexpression group was lower than that of patients in the ERCC1 underexpression group (p = 0.029); however, no significant difference was found in the mutant KRAS patient group (p = 0.671). ConclusionsOur results suggest that CRC with wild-type KRAS and ERCC1 overexpression might be associated with oxaliplatin resistance. When considering oxaliplatin-based chemotherapy, the status of both KRAS mutation and ERCC1 overexpression should be evaluated.

Implications of KRAS mutations in acquired resistance to treatment in NSCLC.

RationaleKRAS is the most common and, simultaneously, the most ambiguous oncogene implicated in human cancer. Despite KRAS mutations were identified in Non Small Cell Lung Cancers (NSCLCs) more than 20 years ago, selective and specific inhibitors aimed at directly abrogating KRAS activity are not yet available. Nevertheless, many therapeutic approaches have been developed potentially useful to treat NSCLC patients mutated for KRAS and refractory to both standard chemotherapy and targeted therapies.The focus of this review will be to provide an overview of the network related to the intricate molecular KRAS pathways, stressing on preclinical and clinical studies that investigate the predictive value of KRAS mutations in NSCLC patients.Materials and MethodsA bibliographic search of the Medline database was conducted for articles published in English, with the keywords KRAS, KRAS mutations in non-small cell lung cancer, KRAS and tumorigenesis, KRAS and TKIs, KRAS and chemotherapy, KRAS and monoclonal antibody, KRAS and immunotherapy, KRAS and drugs, KRAS and drug resistance.

What is the significance of TP53 and KRAS mutation for immunotherapy in non-small cell lung cancer?

Increasing evidences including PD-L1 expression (1,2), tumor mutation burden (TMB) (3,4), and the intensity of CD8+ T cell infiltrates (5-7) have been respectively certified as predictive biomarkers of response to immunotherapy. More recently, our study identified TP53/KRAS mutation may be another applicable factor to predict response to PD-1 blockade in non-small cell lung cancer (NSCLC) (8). This result has aroused some discussions. Dr. Tawee Tanvetyanon (9) raises a question of when is KRAS or TP53 mutation predictive of response to immunotherapy for lung cancer? He points out that it is not adequate enough to demonstrate the predictive value of KRAS mutation independently from TMB and that TP53 or KRAS mutation may be served as a predictive biomarker along with high TMB.

Co-existance of KRAS and LKB1 mutation as predictor of resistance to Erlotinib: Customized next-generation sequencing (NGS) of TAILOR trial.

e20631 Background: The prognostic and predictive value of KRAS mutation in advanced NSCLC is still debatable. In TAILOR (NCT00637910) trial EGFR wild-type patients were randomized to receive 2nd line erlotinib versus docetaxel, and no interaction was detected according to KRAS mutational status. Recent evidences indicate that the concurrent mutation of KRAS and LKB1 (key factor for cell metabolism) may be associated with worse prognosis. Methods: Availableformalin-fixed embeddedtissue samples with annotated clinical data from TAILOR were gathered. Customized deep sequencing (Ion proton Technology) of 111 genes most frequently associated with cancer, was performed; 5% of frequency was used to identify mutations. Association between genes and clinical features was performed with non-parametric tests; Cox regression analysis was used to assess the prognostic and predictive value of LKB1. Results: 123 out of 222 (55%) randomized patients had available tissue and were successfully sequenced. 42/123 (34%) patients had a KRAS mutation. KRAS and LKB1 mutations were found in 11/42 (26%) KRAS patients, while only 6 patients had a LKB1 mutation without KRAS. The presence of a concurrent KRAS-LKB1 mutation did not adversely influence progression-free (PFS) or overall (OS) survival [hazard ratio (HR) PFS 1.08, 95% confidence interval (CI) 0.57-2.05, P = 0.81; OS 1.09, 95% CI 0.56-2.14, P = 0.78]. Patients receiving docetaxel experienced longer survival regardless of the KRAS-LKB1 mutational status (mutated KRAS-LKB1 HR 0.42, 95% CI 0.08-2.29; wild-type KRAS-LKB1 HR 1.16, 95% CI 0.72-1.87, P = 0.55; interaction P = 0.10). Conclusions: Although the significant attrition and the limited number, these data generate the hypothesis that the concurrent mutation of KRAS and LKB1 may potentially be associated with resistance to erlotinib. Overall, the coexistence of mutation in KRAS and LKB1 is not associated with worse prognosis in NSCLC. For these patients refractory to EGFR targeting, metabolic strategies represent a future research opportunity.

KRAS G12C mutation as a poor prognostic marker of pemetrexed treatment in non-small cell lung cancer.

Background/AimsThe predictive and prognostic value of KRAS mutation and its type of mutations in non-small cell lung cancer (NSCLC) are controversial. This clinical study was designed to investigate the predictive value of KRAS mutations and its mutation types to pemetrexed and gemcitabine based treatment.MethodsAdvanced NSCLC patients tested for KRAS mutation (n = 334) were retrospectively reviewed and 252 patients with wild type epidermal growth factor receptor and no anaplastic lymphoma kinase fusion were enrolled for the analysis. KRAS mutations were observed in 45 subjects with mutation type as followed: G12C (n = 13), G12D (n = 12), G12V (n = 12), other (n = 8). Response rate (RR), progression-free survival (PFS), and overall survival (OS) of pemetrexed singlet and gemcitabine based chemotherapy were analysis.ResultsAge, sex, performance status were well balanced between subjects with or without KRAS mutations. No difference was observed in RR. Hazard ratio (HR) of PFS for pemetrexed treated subjects with G12C mutation compared to subjects with KRAS wild type was 1.96 (95% confidential interval [CI], 1.01 to 3.79; p = 0.045), but other mutations failed to show clinical significance. By analysis done by PFS, compared to the subjects with transition mutation, HR was 1.48 (95% CI, 0.64 to 3.40; p = 0.360) for subjects with transversion mutation on pemetrexed treatment and 0.41 (95% CI, 0.19 to 0.87; p = 0.020) for subjects treated with gemcitabine based chemotherapy. No difference was observed in OS.ConclusionsIn this study, different drug sensitivity was observed according to the type of KRAS mutation. NSCLC subpopulations with different KRAS mutation type should be considered as different subgroups and optimal chemotherapy regimens should be searched in further confirmative studies.

Targeting KRAS mutated non-small cell lung cancer: A history of failures and a future of hope for a diverse entity.

Lung cancer remains the leading cause of cancer-related deaths in both men and women. However, the discovery of several oncogenic driver mutations and the development of immune checkpoint inhibitors resulted in improved clinical outcomes for most patients. Although activating KRAS mutations are the most common recurring molecular events in lung adenocarcinoma, little progress has been made during the past decades with no new agents being approved for this indication. The elucidation of the underlying biology of this diverse patient subgroup offers great potential and renewed hope regarding the rational development, rigorous evaluation and subsequent approval of novel targeted agents and combinations which will effectively suppress compensatory escape routes and the emergence of resistance, issues that have plagued previous attempts. Here, we review in a structured manner all aspects of KRAS positive non-small cell lung cancer, including the molecular biology, clinicopathologic characteristics, the prognostic and predictive value of KRAS mutations, as well as previous and contemporary approaches towards the treatment of this elusive target.

The value of KRAS mutation testing with CEA for the diagnosis of pancreatic mucinous cysts.

Background and aims: Pancreatic cyst fluid (PCF) CEA has been shown to be the most accurate preoperative test for detection of cystic mucinous neoplasms (CMNs). This study aimed to assess the added value of PCF KRAS mutational analysis to CEA for diagnosis of CMNs. Patients and methods: This is a retrospective study of prospectively collected endoscopic ultrasonography (EUS) fine-needle aspiration (FNA) data. KRAS mutation was determined by direct sequencing or equivalent methods. Cysts were classified histologically (surgical cohort) or by clinical (EUS or FNA) findings (clinical cohort). Performance characteristics of KRAS, CEA and their combination for detection of a cystic mucinous neoplasm (CMN) and malignancy were calculated. Results: The study cohort consisted of 943 patients: 147 in the surgical cohort and 796 in the clinical cohort. Overall, KRAS and CEA each had high specificity (100 % and 93.2 %), but low sensitivity (48.3 % and 56.3 %) for the diagnosis of a CMN. The positivity of KRAS or CEA increased the diagnostic accuracy (80.8 %) and AUC (0.84) significantly compared to KRAS (65.3 % and 0.74) or CEA (65.8 % and 0.74) alone, but only in the clinical cohort (P < 0.0001 for both). KRAS mutation was significantly more frequent in malignant CMNs compared to histologically confirmed non-malignant CMNs (73 % vs. 37 %, P = 0.001). The negative predictive value of KRAS mutation was 77.6 % in differentiating non-malignant cysts. Conclusions: The detection of a KRAS mutation in PCF is a highly specific test for mucinous cysts. It outperforms CEA for sensitivity in mucinous cyst diagnosis, but the data does not support its routine use.

G12V and G12A KRAS mutations are associated with poor outcome in patients with metastatic colorectal cancer treated with bevacizumab.

The v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are found in 35-45% of colorectal cancer (CRC) cases. Although the association between the RAS signaling and angiogenesis is well known, the negative predictive value of KRAS mutation has not been established in patients treated with bevacizumab. The aim of this study was to evaluate the association between specific KRAS mutation types and outcome of patients with metastatic CRC treated with bevacizumab. The study included 404 patients with metastatic CRC (mCRC) treated with bevacizumab. Clinical data obtained from the clinical registry CORECT were retrospectively analyzed. The shortest survival was observed in patients with tumors harboring G12V or G12A KRAS mutation (G12V/A). The median progression-free survival (PFS) and overall survival (OS) for patients with tumors harboring G12V/A KRAS mutation was 6.6 and 16.8 compared to 11.6 and 26.3months for patients with tumors harboring other KRAS mutation type (p < 0.001 and p < 0.001), while the survival of patients harboring other KRAS mutation types was comparable to those with tumors harboring wild-type KRAS gene. In the Cox multivariable analysis, KRAS G12V/A mutation type remains a significant factor predicting both PFS (HR = 2.18, p < 0.001) and OS (HR = 2.58, p < 0.001). In conclusion, the results of the present study indicate that there is a significant difference in biological behavior between tumors harboring G12V/A and other KRAS mutations. Moreover, comparison of the survival of patients with tumors harboring G12V/A KRAS mutations with those harboring wild-type KRAS gene revealed that G12V/A KRAS mutations are prognostic biomarker for inferior PFS and OS in patients with mCRC treated with bevacizumab in univariate as well as multivariable analyses.

Value of KRAS as prognostic or predictive marker in NSCLC: results from the TAILOR trial

BackgroundThe prognostic and predictive role of KRAS mutations in advanced nonsmall-cell lung cancer (NSCLC) is still unclear. TAILOR prospectively assessed the prognostic and predictive value of KRAS mutations in NSCLC patients treated with erlotinib or docetaxel in second line. Patients and methodsNSCLC patients from 52 Italian hospitals were genotyped for KRAS and EGFR mutational status in two independent laboratories. Wild-type EGFR patients (N = 218) received first-line platinum-based chemotherapy and were randomly allocated at progression to erlotinib or docetaxel. Overall survival (OS) according to KRAS mutational status was the primary end point. ResultsKRAS mutations were present in 23% of TAILOR randomized cases. The presence of a KRAS mutation did not adversely affect progression-free (PFS) or overall (OS) survival [hazard ratio (HR) PFS = 1.01, 95% confidence interval (CI) 0.71–1.41, P = 0.977; OS = 1.24, 95% CI 0.87–1.77, P = 0.233], nor influenced treatment outcome (test for interaction: OS P = 0.965; PFS P = 0.417). Patients randomized to docetaxel treatment experienced longer survival independently from the KRAS mutational status of their tumors (HR: mutated KRAS 0.81, 95% CI 0.45–1.47; wild-type KRAS 0.79, 95% CI 0.57–1.10). ConclusionIn TAILOR, KRAS was neither prognostic nor predictive of benefit for either docetaxel or erlotinib. Docetaxel remains superior independently from KRAS status for second-line treatment in EGFR wild-type advanced NSCLC patients. Clinical trial registrationNCT00637910.

Prognostic and Predictive Value of KRAS Mutations in Advanced Non-Small Cell Lung Cancer

Clinical implications of KRAS mutations in advanced non-small cell lung cancer remain unclear. We retrospectively evaluated the prognostic and predictive value of KRAS mutations in patients with advanced NSCLC. Among 484 patients with available results for both KRAS and EGFR mutations, 39 (8%) had KRAS and 182 (38%) EGFR mutations, with two cases having both mutations. The median overall survivals for patients with KRAS mutations, EGFR mutations, or both wild types were 7.7, 38.0, and 15.0 months, respectively (P<0.001). The KRAS mutation was an independent poor prognostic factor in the multivariate analysis (hazard ratio = 2.6, 95% CI: 1.8–3.7). Response rates and progression-free survival (PFS) for the pemetrexed-based regimen in the KRAS mutation group were 14% and 2.1 months, inferior to those (28% and 3.9 months) in the KRAS wild type group. KRAS mutation tended to be associated with inferior treatment outcomes after gemcitabine-based chemotherapy, while there was no difference regarding taxane-based regimen. Although the clinical outcomes to EGFR tyrosine kinase inhibitors (TKIs) seemed to be better in patients with KRAS wild type than those with KRAS mutations, there was no statistical difference in response rates and PFS according to KRAS mutation status when EGFR mutation status was considered. Two patients with both KRAS and EGFR mutations showed partial response to EGFR TKIs. Although G12D mutation appeared more frequently in never smokers, there was no difference in clinical outcomes according to KRAS genotypes. These results suggested KRAS mutations have an independent prognostic value but a limited predictive role for EGFR TKIs or cytotoxic chemotherapy in advanced NSCLC.

KRAS Mutation: Should We Test for It, and Does It Matter?

Lung cancer is the leading cause of cancer mortality in the United States and worldwide. Previously, lung cancer was simplistically divided into non-small-cell lung cancer (NSCLC) and small-cell lung cancer. However, in the last decade, we have gone from a simplistic binary system of classifying lung cancer to defining NSCLC on the basis of molecular subsets. KRAS mutations represent the most common molecular change in NSCLC. The presence of KRAS mutation has been shown to be associated with a poor prognosis in NSCLC, but this is of little clinical utility. More important is determining the clinical utility of KRAS mutational analysis for predicting benefit of chemotherapy, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), anti-EGFR monoclonal antibodies, or other novel therapeutics. Current data does not support the routine use of KRAS mutational analysis for predicting chemotherapy benefit. Additionally, there was significant interest in using KRAS status to select patients for EGFR TKI and anti-EGFR monoclonal antibodies. However, the EGFR mutational status has demonstrated significant predictive value in the selection of patients for EGFR TKI therapy and is now the preferred test. An association between KRAS mutational status and benefit of anti-EGFR monoclonal antibodies has not been demonstrated in NSCLC. Here we review, in the context of NSCLC, the underlying biology of KRAS mutations, the predictive value of KRAS mutations for therapeutic intervention, and the integration of KRAS mutational testing into our current clinical paradigms.

KRAS Mutation in Patients with Lung Cancer: A Predictor for Poor Prognosis but Not for EGFR-TKIs or Chemotherapy

The prognostic and predictive value of KRAS mutations in patients with lung cancer is controversial. Biases in disease stage, treatment regimen, small-scale patient studies, and biomarker status have led to inconsistent results in previous reports. The KRAS and EGFR genes were examined in 1935 consecutive patients with non-small cell lung cancer. All patients were divided into KRAS mutation (KRAS group), EGFR mutation (EGFR group), and KRAS/EGFR wild type (WT group) groups. Randomly selected cases were paired with patients with the KRAS mutation, the EGFR mutation, and KRAS/EGFR wild type patients according to tumor, node, metastasis stage, time of first visit within 1year, and pathology. Progression-free survival (PFS) and overall survival were evaluated by Kaplan-Meier and Cox models. The KRAS mutation rate for lung adenocarcinoma was 5.90%. The overall survival was 14.47, 20.57, and 42.73months for the KRAS group, WT group, and EGFR group, respectively (P<0.001). Multivariate analysis indicated that KRAS mutation status was an independent prognostic factor (hazard ratio 2.69, 95% confidence interval 1.91-3.80, P<0.001). No difference was found in PFS and tumor responsiveness between patients with a KRAS mutation and those with wild type KRAS/EGFR for chemotherapy and EGFR tyrosine kinase inhibitors (TKI). PFS did not significantly differ for chemotherapy among the three groups (P=0.270). KRAS mutation is a poor prognosis factor, but it is not an independent predictor of response to EGFR-TKI or chemotherapy in patients with lung cancer.

Predictors of EGF receptor monoclonal antibody activity in metastatic colorectal cancer: current status

SUMMARY In the treatment of metastatic colorectal cancer, the cytostatic drugs 5-fluorouracil, irinotecan and oxaliplatin, as well as the VEGF antibody bevacizumab, are applied without the use of predictive biomarkers. To date, KRAS mutational status is the only accepted predictive biomarker, limiting the use of the EGF receptor (EGFR) monoclonal antibodies cetuximab and panitumumab to patients with KRAS wild-type tumors. The different KRAS mutations on codons 12 and 13 represent a negative predictive biomarker with poor positive predictive power. The negative predictive value of KRAS mutations has been questioned by several retrospective analyses of clinical trials, hypothesizing variable efficacies of EGFR antibodies associated with the diverse range of mutations. While the BRAF mutation is associated with a negative prognosis, its predictive value in the context of EGFR monoclonal antibody therapy is not fully understood. The present review aims to outline possible clinical and molecular biomarkers of EGFR monoclonal antibodies in metastatic colorectal cancer.

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.

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 340: Predictive value of KRAS mutations in advanced non-small cell lung cancer (NSCLC) patients (pts) treated with chemotherapy (CT)

Abstract Introduction: KRAS mutation is thought to be related with poor outcome of NSCLC pts. The predictive value of KRAS mutation for response to chemotherapy (CT) has not been established Patients and methods: From a retrospective database from 2 university hospitals all pts with advanced NSCLC treated with palliative platinum containing chemotherapy were selected. Pts were included when archive tumor tissue was available for DNA extraction. High resolution melting followed by PCR sequencing was performed for KRAS exon1 and 2. Results: KRAS mutation analysis was evaluable for 122 pts. All pts had advanced NSCLC and were no candidate for treatment with curative intent. Mean age 61 years (range 24-80 years), 81 males and 41 females. All pts received platinum-containing CT. Response was evaluable for 110 pts: 1 complete response, 21 partial response, 54 stable disease and 54 progressive disease. Median progression free survival (PFS) was 5.7 months (m) (95% CI 4.2-7.2 m), median overall survival (OS) was 7.5 m (94% CI 5.2-9.9 m). 44 pts (36%) had a KRAS mutation. 38% of pts with a KRAS mutation had as best response PD on CT, and 27% of pts without a KRAS mutation had PD, this difference was not significant. No difference in PFS and OS was observed for pts with a KRAS mutation (median PFS 5.3 m, 95% CI 3.2-7.3 m and median OS 6.2 m, 95% CI 4.8-7.3 m) and without a KRAS mutation (median PFS 6.1, 95% CI 5.0-7.2m and median OS 8.9 m, 95% CI 6.4-11.4). Conclusion: In our series KRAS mutation was not predictive for response to platinum containing CT in pts with advanced NSCLC. Furthermore, KRAS mutation was not prognostic. Additional data on specific KRAS mutations will be presented. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 340. doi:10.1158/1538-7445.AM2011-340

Molecular Predictors of Efficacy to Anti-EGFR Agents in Colorectal Cancer Patients

Recent insights into the molecular pathogenesis of colorectal cancer (CRC) have given rise to specific target-directed therapies, including monoclonal antibodies (mAb) against epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF). These drugs have been approved as first, second and third line therapies for metastatic CRC (mCRC) and the advent of target-specific cancer therapeutics has remarkably improved the outcomes of patients with CRC. The molecular mechanisms underlying the clinical response to these drugs are not fully understood, although recent studies have elucidated the effect of intracellular signaling pathways involving in particular RAS/RAF/MAPK signaling on the safety and efficacy of target-specific drugs. Activating mutations of KRAS and BRAF genes are genetic events in tumorigenesis and these mutations are implicated as predictive factors in determining response, in particular to anti-EGFR drugs, and additional data suggest that other EGFR downstream pathways such as PI3K/PTEN/Akt or JAK/STAT are also important when considering mechanisms of EGFR antibody resistance. Recently the European Medical Agency (EMEA) approved the use of the mAb Panitumumab (December 2007) and approved a license extension for the use of the mAb Cetuximab in combination with chemotherapy as first-line treatment (October 2008) in mCRC patients with no mutations in the codon 12 and 13 of KRAS gene. The predictive value of KRAS mutations in the treatment of CRC has been very useful to clinicians and patients in terms of decision making, avoiding toxicities, and decreasing financial burden. This success also encourages researchers to find new markers with the same strong predictive value. Future studies also need to identify patterns of multiple mutations to further increase the power of patient selection for anti-EGFR therapy. These advances allow us to truly enter a new and exciting era of individualized therapy in oncology. Here we review the molecular basis of EGFR-targeted therapies and the resistance to treatments conferred by KRAS and other gene mutations as well as the laboratory methods used to detect all these genetic variations.

Are RAS mutations predictive markers of resistance to standard chemotherapy?

KRAS mutations may be predictive of resistance to anti-EGFR monoclonal-based therapy in patients with colorectal cancer (CRC). Screening for KRAS mutations in patients with CRC and non-small-cell lung cancer (NSCLC) may provide additional information on optimizing treatment options with targeted therapies. Only limited studies, however, have assessed the predictive value of KRAS mutations in response to conventional chemotherapy. We reviewed all relevant papers investigating the association of KRAS mutations and conventional chemotherapy-related outcome in NSCLC, CRC, and other solid tumors, both in the adjuvant and advanced settings. Our Review strongly suggests that KRAS mutations have no value in response prediction to conventional chemotherapy in NSCLC, CRC and other solid tumors. Therefore, KRAS mutations should not be used as molecular predictors of response to conventional chemotherapy.