Prognostic Value Of KRAS Mutations Research Articles

Impact ofKRASmutation and PTEN expression on cetuximab-treated colorectal cancer

To investigate the prognostic value of KRAS mutation, and phosphatase and tensin (PTEN) expression in Chinese metastatic colorectal cancer metastatic colorectal cancer (mCRC) patients treated with cetuximab. Ninety Chinese mCRC patients treated with cetuximab were evaluated for KRAS mutation and PTEN protein expression by DNA sequencing of codons 12 and 13 and immunohistochemistry, respectively. We then selected 61 patients treated with cetuximab, either in combination with chemotherapy, or alone as a second-line or third-line regimen to assess whether KRAS mutation or PTEN protein expression is associated with the response and the survival time of mCRC patients treated with cetuximab. KRAS mutation was found in 30 (33.3%) tumor samples from the 90 patients, and positive PTEN expression was detected in 58 (64.4%) of the 90 patients. Among the 61 patients who were treated with cetuximab as a second-line or third-line regimen, the resistance to cetuximab was found in 22 patients with KRAS mutation and in 39 patients without KRAS mutation, with a response rate of 4.5% and 46.1% respectively (P = 0.001), a shorter median progression-free survival (PFS) time of 14 ± 1.3 wk and 32 ± 2.5 wk respectively (P < 0.001), a median overall survival (OS) time of 11 ± 1.2 mo and 19 ± 1.8 mo respectively (P < 0.001), as well as in 24 patients with negative PTEN expression and in 37 patients with positive PTEN expression respectively (P < 0.001), with a responsive rate of 4.2% and 48.6% respectively, a shorter median PFS survival time of 17 ± 2.0 wk and 28 ± 1.9 wk respectively (P = 0.07), and a median OS time of 11 ± 1.3 mo and 18 ± 1.9 mo respectively (P = 0.004). Combined KRAS mutation and PTEN expression analysis showed that the PFS and OS time of patients with two favorable prognostic factors were longer than those of patients with one favorable prognostic factor or no favorable prognostic factor (P < 0.001). KRAS mutation and PTEN protein expression are significantly correlated with the response rate and survival time of Chinese mCRC patients treated with cetuximab.

KRAS mutations and relation to prognosis in patients operated for localized pancreatic cancer and other periampullary cancers

e15618 Background: Prognostic biomarkers in patients with pancreatic cancer might direct patients to optimal treatment. We studied the prognostic value of KRAS mutations in patients operated for pancreatic and other periampullary cancers. Methods: Retrospective study of 328 patients who were operated with a Whipples procedure at a single HBP-center during the period August 1976 to May 2008. For the present pilot study cancer tissue blocks were collected from 58 patients (31 men, 27 women, median age 64, range 33–81 years, ASA 1–3). All had localized pancreatic (n=26), ampullary (n=26) or duodenal cancer (n=6) and were operated during the period June 2001 to May 2008. 32 patients died (3 within the first month after operation and were excluded). Median follow-up time was 41 months (range 7–90). KRAS mutations in exon 1 and 2 were determined by LightScanner analysis (Idaho Technology). Results: KRAS mutations were found in 32 (55%) of the patients; 16 (62%) patients with pancreatic cancer, 13 (50%) with ampullary cancer and in 3 (50%) with duodenal cancer. KRAS status was neither associated with type of cancer (p=0.68), TNM stage (T stage p=0.64, N stage p=0.31). The median survival time for all patients was 22 months (KRAS mutation: 21, 95% CI: 10–40; Wildtype: not reached yet). Univariate Cox analysis showed that T stage (TNM) (1: HR=0.09, 95% CI: 0.02–0.48 p=0.004; 2: HR=0.18, 0.06- 0.51, p=0.0013; 3: HR=0.26, 0.09–0.71, p=0.0089) was a prognostic factor of OS. KRAS status (HR=0.70, 0.33–1.49, p=0.36) and N stage (TNM) (HR=0.53, 0.25–1.11, p=0.09) were not significant factors of OS, but there is a strong tendency for both factors. Conclusions: KRAS mutations are frequent in patients with localized pancreatic, ampullary and duodenal cancers. Preliminary analysis of 58 patients out of our cohort of 328 patients indicate that KRAS mutations may be a marker of overall survival and time to progression. No significant financial relationships to disclose.

Prognostic value of KRAS mutations and Ki-67 expression in stage I lung adenocarcinomas

The purpose of the present study was to establish accurate prognostic markers to predict the post-operative recurrence of stage I lung adenocarcinomas (ADC). One-hundred and ninety cases of stage I ADC were examined for KRAS mutations and Ki-67 expression, and their associations with disease recurrence were analyzed. KRAS-mutated cases showed a significantly higher risk of recurrence than cases without mutations (5-year disease-free survival (DFS) 61.0% vs. 85.8%, P = 0.017: adjusted Hazard ratio (HR) 4.55, 95% Confidence Interval (CI) 1.61–12.82, P = 0.004). Ki-67 high-expressers (labeling index >10%) also showed a higher risk of recurrence than low-expressers (5-year DFS 68.7% vs. 93.2%, P < 0.001: adjusted HR 3.84, 95% CI 1.18–12.45, P = 0.025). Ki-67 high-expressers with KRAS mutations showed an additional higher risk of recurrence compared to low-expressers without mutations (5-year DFS 37.5% vs. 93.3%, P < 0.001: adjusted HR 16.82, 95% CI 3.77–74.98, P < 0.001) and their 5-year DFS was nearly equivalent to that of stage II non-small cell lung cancer (NSCLC) in our facility (37.5% vs. 37.2% for stage II NSCLC, p = 0.577). The combined use of KRAS status and Ki-67 expression level could be an excellent prognostic marker to predict the post-operative recurrence of stage I ADC.

K-Ras Mutations and Treatment Outcome in Colorectal Cancer Patients Receiving Exclusive Fluoropyrimidine Therapy

K-Ras mutations predict resistance to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies. Because combinations of anti-EGFR with 5-fluorouracil (5-FU)-based chemotherapy are promising treatments, we analyzed the effect of K-Ras mutations in patients having received exclusive 5-FU therapy. This study was conducted on 93 stage IV colorectal cancer patients with unresectable measurable liver metastasis receiving 5-FU-leucovorin (56 men and 37 women; 77 cancer deaths). Liver metastases (n = 93) along with primary tumors (n = 48) were analyzed for K-Ras mutations (codons 12 and 13), p53 mutations (exons 4-9), p53 polymorphism (codon 72), thymidylate synthase (TS) polymorphism (28-bp repeats including G>C mutation), methylenetetrahydrofolate reductase polymorphism (677C>T, 1298A>C), thymidylate synthase (TS) activity, dihydropyrimidine dehydrogenase activity, folylpolyglutamate synthase activity, and p53 protein expression. Thirty-six of 93 (38.7%) metastases were K-Ras mutated (30 at codon 12 and 6 at codon 13). Mutated primary tumors (16 of 48) matched perfectly with mutated metastases. The additional analyzed tumor markers were not different between K-Ras mutated and wild-type tumors. The objective response rate was 37%: 44.4% in K-Ras mutated versus 32.1% in wild-type K-Ras metastasis (P = 0.27). Low TS activity in metastasis was the only significant predictor of tumor response (P = 0.047). K-Ras status did not influence specific survival. The present data indicate a perfect concordance of K-Ras mutations between primary and liver metastasis and suggest that any predictive and/or prognostic value of K-Ras mutations in treatments combining anti-EGFR monoclonal antibodies with 5-FU should be exclusively linked to the anti-EGFR agent.

KRAS Mutations As an Independent Prognostic Factor in Patients With Advanced Colorectal Cancer Treated With Cetuximab

Cetuximab is efficient in advanced colorectal cancer (CRC). We previously showed that KRAS mutations were associated with resistance to cetuximab in 30 CRC patients. The aim of this study was to validate, in an independent larger series of 89 patients, the prognostic value of KRAS mutations on response to cetuximab and survival. Eighty-nine metastatic CRC patients treated with cetuximab after treatment failure with irinotecan-based chemotherapy were analyzed for KRAS mutation by allelic discrimination on tumor DNA. The association between KRAS mutations and tumor response, skin toxicity, progression-free survival (PFS) and overall survival (OS) was analyzed. A KRAS mutation was present in 27% of the patients and was associated with resistance to cetuximab (0% v 40% of responders among the 24 mutated and 65 nonmutated patients, respectively; P < .001) and a poorer survival (median PFS: 10.1 v 31.4 weeks in patients without mutation; P = .0001; median OS: 10.1 v 14.3 months in patients without mutation; P = .026). When we pooled these 89 patients with patients from our previous study, the multivariate analysis showed that KRAS status was an independent prognostic factor associated with OS and PFS, whereas skin toxicity was only associated with OS. In a combined analysis, median OS times of patients with two, one, or no favorable prognostic factors (severe skin toxicity and no KRAS mutation) was of 15.6, 10.7, and 5.6 months, respectively. These results confirm the high prognostic value of KRAS mutations on response to cetuximab and survival in metastatic CRC patients treated with cetuximab.

Gender Differences: Implications for Clinical Trials and Practice

Gender Differences: Implications for Clinical Trials and Practice

The Ras/Raf/MAPK Pathway

The Ras/Raf/MAPK pathway is probably the best characterized signal transduction pathway in cell biology. The function of this pathway is to transduce signals from the extracellular milieu to the cell nucleus where specific genes are activated for cell growth, division and differentiation. The Ras/Raf/MAPK pathway is also involved in cell cycle regulation, wound healing and tissue repair, integrin signaling and cell migration.1–3 Finally, the Ras/Raf/MAPK pathway is able to stimulate angiogenesis through changes in expression of genes directly involved in the formation of new blood vessels.4 Thus, signaling through the Ras/Raf/MAPK regulates a variety of cellular functions that are important for tumorigenesis. Dysregulation of this pathway is a common event in cancer as Ras is the most frequently mutated oncogene in human cancer. Mutations in the K-ras oncogene have been localized in codons 12, 13, 59 and 61 with those at codons 12 and 61 occurring most frequently. K-ras mutations are present in 15-50% of lung cancers and in 72–90% of pancreatic cancers.5,6 Even in the absence of activating mutations, K-ras still plays a role in oncogenesis via Ras gene amplification, overexpression or upstream activation of the pathway. Each of these potential cellular alterations will produce increased activation of Ras effectors, thereby promoting development of tumors. For example, 40% of esophageal cancers have amplification of the K-ras gene7 and in approximately 50% of breast cancers, Ras is highly active in association with expression of HER-2/Neu receptors.8 Mutations in other members of the pathway are also common in other forms of cancers. Somatic B-raf mutations have been found in 60-70% of malignant melanomas and are also seen in papillary thyroid cancer, colon and ovarian cancers.9 Furthermore, activation of MAPK –not associated with either K-ras or BRAF activating mutations are seen in 41% of low-grade ovarian serous carcinomas.10 The ras superfamily of genes encodes small GTPbinding proteins that are responsible for regulation of many cellular processes, including differentiation, cytoskeletal organization, and protein trafficking.11 Oncogenic ras genes in human cells include H-ras, N-ras and K-ras.12 The 21-kd transforming proteins Hand Kras genes were first identified as the counterparts of the oncogenes of the Harvey and Kirsten rat sarcoma viruses, whereas the N-ras oncogene was isolated from a neuroblastoma and has not been found in any retroviruses.12 Since mutations in K-ras and not in H-ras or N-ras are common in lung cancer, this review will focus on K-ras. K-ras is initially synthesized as an inactive cytosolic pro-peptide. Then the protein undergoes a series of posttranslational modifications at its carboxyl terminus that increase its hydrophobicity allowing its localization to the lipid-rich cell membrane.13 An important post-translational modification is farnesylation in the hydrophobic tail of the carboxyl terminal group. This reaction is catalyzed by the enzyme farnesyltransferase which adds a 15-carbon hydrobobic farnesyl isoprenyl to the carboxyl terminus of Ras. Once in the cell membrane, K-ras cycles between inactive guanosine diphosphate–bound and active guanosine triphosphate (GTP) –bound states, thereby activating a series of effector kinases –such as Raf and MAPKthat phosphorylate a cascade of signaling proteins.14 The principal consequence of the mutated proteins is a marked decrease in interactions between Ras and its GTPase activator protein.15 Instead of reverting to its inactive guanosine diphosphate–bound state, the modified conformation of mutant Ras favors its active GTP-bound state, which has a higher propensity to activate downstream effectors even in the absence of growth factor stimulation, conferring a proliferative advantage to tumors. Activation of the pathway begins when a signal binds to a protein tyrosine kinase receptor. The epidermic growth factor receptor (EGFR) and the platelet-derived growth factor receptor (PDGFR) are the best-known receptors in the pathway. However, multiple upstream receptors including other receptor tyrosine kinases, integrins, serpentine receptors, heterotrimeric G-proteins and cytokine receptors are able to activate K-ras.16 Binding of a ligand to EGF receptor induces oligomerization of the receptor, a process that results in juxtaposition of the cytoplasmic, catalytic domains in a manner that allows activation of the kinase activity and transphosphorylation.17 Adaptor proteins such as Grb2 are now able to recognize sequence homology 2 (SH2) domains such as Shc, which in turn, recruit guanine nucleotide exchange factors (GEFs) like SOS-1 or CDC25 to the cell membrane17 (figure 1). The GEF becomes capable of interacting with Ras proteins at the cell membrane to promote a conformational change and the exchange of GDP for GTP. Following Ras activation, Raf is recruited to the cell membrane through Division of Medical Oncology Mayo Clinic, Rochester, MN Submitted for publication Accepted for publication Correspondence to: Julian R. Molina, MD., Ph.D Division of Medical Oncology Mayo Clinic Rochester, MN 55905 Phone: 507284 2511 FAX: 507 -284 1803 Molina.julian@mayo.edu Copyright © 2006 by the International Association for the Study of Lung Cancer ISSN: 1556-0864/06/0101-0007

Reconfirming the prognostic value of K-ras mutations in resected non-small-cell lung cancer (NSCLC) including squamous cell carcinoma (SCC)

Reconfirming the prognostic value of K-ras mutations in resected non-small-cell lung cancer (NSCLC) including squamous cell carcinoma (SCC)

Implications and prognostic value of K-ras mutation for early-stage lung cancer in women.

Because there is no clear consensus as to the predictive value of K-ras gene mutation for survival in patients with lung cancer, we examined the occurrence of K-ras mutations in a large, prospective case series of non-small-cell lung cancer (NSCLC). Our goals were to define the patient characteristics associated with K-ras mutation and to determine whether mutation of this gene might be a biomarker of patient prognosis. Consecutive, newly diagnosed patients with lung cancer treated with potentially curative resection over a 4-year period were recruited for study. The mutation status of K-ras codon 12 in each patient's tumor DNA was determined by means of polymerase chain reaction-restriction fragment length polymorphism analysis of archived pathology specimens. Analyses were restricted to adenocarcinoma. There was a statistically significant association between female sex and K-ras mutation after adjustment for carcinogen exposures (odds ratio = 3.3; 95% confidence interval [CI] = 1.3-7.9); mutations were found only in smokers. Comparison of Kaplan-Meier curves indicated a strong association between K-ras mutation and decreased patient survival (two-sided P =.009); analysis stratified by pathologic staging groups revealed that this association was statistically significant only for stage I tumors (two-sided P =.002). Cox proportional hazards modeling indicated that K-ras codon 12 mutation was a statistically significant predictor of patient survival, after adjustment for the effects of age, sex, and stage (risk ratio = 1.8; 95% CI = 1.1-3.1). After adjustment for environmental exposures, non-small-cell lung tumors in women appear to be more likely than those in men to harbor K-ras mutations, suggesting a possible role of estrogen exposure in either the initiation or the selection of K-ras mutant clones in adenocarcinoma. In addition, our data suggest that K-ras codon 12 mutation is a marker of aggressive NSCLC, as evidenced by its association with decreased patient survival, particularly for early-stage disease.

Prognostic value of K-ras mutations, ras oncoprotein, and c-erb B-2 oncoprotein expression in adenocarcinoma of the lung.

This trial was undertaken to determine the prognostic role of K-ras (p21), c-erb B-2 (p185) protein expression, and the presence or nonpresence of a K-ras gene mutation in patients with adenocarcinoma of the lung. This was a retrospective study of 103 patients with adeno- or large-cell carcinoma of the lung who had available paraffin-stored tumor material. The relation of several clinical variables to survival was analyzed. Immunohistochemical techniques were used to determine expression of p21 and p185. Polymerase chain reaction (PCR) and sequencing were used to determine K-ras mutation status. Tumor stage was the only nonmolecular clinical variable predictive of survival (p=0.0001). A combination of K-ras mutation and p 185 expression (p=0.0144), ras mutation and strong p21 expression (p=0.0137), and K-ras mutation and the combined expression of p21 and p185 were predictive of poor survival (p=0.0415) in univariate analysis of all patients. The sole presence of K-ras mutation was predictive of survival. Additionally, when combined with elevated p21 or p185 expression in a subset of patients with 4 or more years of follow-up, negative correlation with survival was observed.

K‐ras mutations in nonmucinous ovarian epithelial tumors

BACKGROUND To assess the putative prognostic value of K-ras mutations in nonmucinous ovarian tumors, the authors looked for K-ras point mutations at codons 12 and 13 in 144 nonmucinous ovarian tumors. METHODS A series of 144 consecutive, unselected, archival, nonmucinous ovarian tumors (35 benign, 12 borderline, and 97 malignant) were studied. K-ras mutations at codons 12 and 13 were determined by polymerase chain reaction using the restriction fragment length polymorphism method with mismatched nested primers. Extensive clinicopathologic and follow-up data on all patients were evaluated. RESULTS The overall prevalence of K-ras mutations at codons 12 and 13 was 30.5% (44/144). In benign tumors, it was 20% (7/35); in borderline tumors, 25% (3/12); and in carcinomas, 35% (34/97). The presence of K-ras point mutations did not correlate with survival. Among the benign tumors, K-ras mutations were detected in three Brenner tumors with a mucinous component. CONCLUSIONS These results indicate that K-ras mutations are not initial events in the pathogenesis of nonmucinous ovarian tumors and do not appear to be related to survival. Cancer 1998;82:1088-95. © 1998 American Cancer Society.

K-ras mutations in nonmucinous ovarian epithelial tumors

To assess the putative prognostic value of K-ras mutations in nonmucinous ovarian tumors, the authors looked for K-ras point mutations at codons 12 and 13 in 144 nonmucinous ovarian tumors. A series of 144 consecutive, unselected, archival, nonmucinous ovarian tumors (35 benign, 12 borderline, and 97 malignant) were studied. K-ras mutations at codons 12 and 13 were determined by polymerase chain reaction using the restriction fragment length polymorphism method with mismatched nested primers. Extensive clinicopathologic and follow-up data on all patients were evaluated. The overall prevalence of K-ras mutations at codons 12 and 13 was 30.5% (44/144). In benign tumors, it was 20% (7/35); in borderline tumors, 25% (3/12); and in carcinomas, 35% (34/97). The presence of K-ras point mutations did not correlate with survival. Among the benign tumors, K-ras mutations were detected in three Brenner tumors with a mucinous component. These results indicate that K-ras mutations are not initial events in the pathogenesis of nonmucinous ovarian tumors and do not appear to be related to survival.