KRAS Mutation Rate Research Articles

Pulmonary adenocarcinoma in situ: analyses of a large series with reference to smoking, driver mutations, and receptor tyrosine kinase pathway activation.

Lung adenocarcinomas in situ (AISs) often occur in individuals who have never smoked, although smoking is one of the main causes of lung cancer. To characterize AIS and, in particular, determine how AIS might be related to smoking, we collected a large number of AIS cases and examined clinicopathologic features, EGFR and KRAS mutation status, and activation status of receptor tyrosine kinase downstream signal pathways, including pAkt, pERK, and pStat3, using immunohistochemistry. We identified 110 AISs (36 smokers and 74 nonsmokers) among 1549 adenocarcinomas resected surgically during 1995 to 2010. Between the AIS of smokers and nonsmokers, only the sex ratio was significantly different; all the other clinicopathologic factors including TTF-1 and driver mutations were not significantly different: EGFR and KRAS mutation rates (smokers:nonsmokers) were 61:58 (%) (P=0.7) and 6.1:1.4 (%) (P=0.2), respectively, whereas, in invasive adenocarcinomas, the rates were 41:69 (%) (P<0.001) and 9.4:2.3 (%) (P<0.04), respectively. For pAkt and pERK, around 40% to 50% of AISs were positive, and for pStat3, >80% were positive, with no significant differences between smokers and nonsmokers with AIS. Mucinous AIS (n=8) rarely harbored KRAS mutations and expressed significantly less pStat3 (P<0.001) than nonmucinous AIS. Taken together, AIS occurs predominantly in female individuals and nonsmokers. However, characteristics of AIS arising in smokers and nonsmokers were similar in terms of cell lineage, driver mutations, and receptor tyrosine kinase pathway activation. Our results suggest that smoking is not a major cause of AIS. Rather, smoking may play a role in progression of AIS to invasive adenocarcinoma with AIS features.

Identification of lung adenocarcinoma mutation status based on histologic subtype: Retrospective analysis of 269 patients.

To evaluate differences in the clinical characteristics and molecular pathology of lung adenocarcinoma subtypes as defined by the new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society international histological classification. We retrospectively reviewed 269 patients with initial primary lung adenocarcinoma who had undergone complete resection at our department from August 2013 to December 2014, focusing on the new histologic subtype classification, clinical characteristics, and molecular pathology. All specimens were invasive adenocarcinoma, and were lepidic (13.0%), papillary (19.7%), acinar (51.7%), solid (8.6%), micropapillary (1.1%) or mucinous predominant (5.9%). Epidermal growth factor receptor (EGFR) mutations were detected in 132 cases (60.3%). Female patients and non-smokers had higher EGFR mutation rates (P = 0.022 and 0.026, respectively). The lepidic, papillary, acinar, solid, micropapillary, and mucinous predominant patterns had EGFR mutation rates of 70.6%, 64.8%, 72.5%, 33.3%, 100%, and 5.9%, respectively. The exon mutation distribution differed according to serum carcinoembryonic antigen (CEA) levels (P = 0.018). v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations were detected in 20 cases (9.2%), and were frequently found in the mucinous and solid predominant subtypes. The serum CEA levels differed among the subtypes. In China, there are significant differences between lung adenocarcinoma histologic subtypes. The presence of well-differentiated components in lung adenocarcinoma indicates higher EGFR mutation rates; the presence of solid or mucinous components indicates higher KRAS mutation rates. Serum CEA levels are associated with histologic subtype and EGFR exon mutations.

Results of observational study to determine K-ras mutation rates in 2458 patients with metastatic colorectal cancer in Turkey (TURKRAS Study).

e14516 Background: Primarily we aimed to investigate the frequency of K-ras mutation in colorectal cancer patients in Turkey, and secondly to determine the frequency of sub-types of the K-ras mutat...

Clinical Research of EGFR and KRAS Mutation in Fine Needle Aspiration Cytology Specimens of Non-small Cell Lung Carcinoma

背景与目的肺癌患者靶向药物治疗前，需要检测表皮生长因子受体（epidermal growth factor receptor, EGFR）和KRAS基因是否突变。本研究旨在探讨细针吸取悬浮液标本检测非小细胞肺癌EGFR、KRAS基因突变的意义。方法细胞学悬浮液标本，Real-time PCR法检测EGFR 18-21号外显子，KRAS 2号外显子12、13密码子突变。结果检测85例肺癌转移淋巴结针吸标本，EGFR突变率37.3%，KRAS突变率7.2%。19例组织切片标本，与细胞学结果一致（kappa=1.0）。13例有EGFR突变，临床分期Ⅳ期患者，使用酪氨酸激酶抑制剂治疗，2例完全缓解（complete remission, CR）（16.7%）；8例部分缓解（partial remission, PR）（66.7%）；3例最佳稳定疾病（stable disease, SD）（25.0%）。结论细针吸取标本检测EGFR、KRAS基因突变，标本取材容易、简单、方便，具有较高的临床实用性。

Prognostic Impact and Clinicopathological Correlations of the Cribriform Pattern in Pulmonary Adenocarcinoma

A novel classification of pulmonary adenocarcinoma (ADC) distinguishing five growth patterns has been established by the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society. There is evidence that an additional cribriform pattern associates with a distinct clinical behavior. We evaluated the predominant growth pattern of 674 resected ADC as recommended by the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society, including the cribriform pattern. The predominant pattern type was correlated with clinical, molecular, and survival data. Two hundred forty-eight (36.8%) of the pulmonary ADC were solid, 207 (30.6%) were acinar, 101 (15%) were papillary, 55 (8.2%) were micropapillary, 35 (5.2%) were lepidic, and 28 cases (4.2%) were cribriform predominant (cpADC). Minor cribriform components were frequently observed (28.6% of all cases). cpADC showed the second highest proliferative capacity of all patterns, no somatic mutations in the epidermal growth factor receptor (p = 0.001) and a high rate of KRAS mutations. Overall survival (OS) of patients with cpADC (mean OS: 62.7 months) ranged in between survival times of patients with acinar (mean OS: 71.3 months) and solid predominant ADC (mean OS: 54.5 months); cpADC was associated with the worst disease-free survival (DFS) of all patterns (mean DFS: 36.9 months). Both associations were confirmed by multivariate analysis (p < 0.01 for both OS and DFS). Hazard ratios for cpADC were 1.72 for OS and 2.99 for DFS, with lepidic predominant ADC set as reference (hazard ratio: 1). Our data support the introduction of cpADC as a novel category into future morphology based on pulmonary ADC classifications. Further international studies are required to validate the reported clinicopathological associations of the cribriform pattern.

Low frequency of KRAS mutation in pancreatic ductal adenocarcinomas in Korean patients and its prognostic value.

Low prevalence and prognostic relevance of KRAS mutations in Korean pancreatic ductal adenocarcinomas (PDACs) need to be validated with sensitive detection method. Peptide nucleic acid (PNA)-mediated polymerase chain reaction (PCR) clamping was used to precisely detect KRAS mutation in 72 paraffinized tumor samples and was validated by pancreatic cell lines to compare the efficiency of direct sequencing. The PNA-mediated PCR clamping detected mutant allele proportions of as low as 0.5% against a background of wild-type DNA and was 20-fold more sensitive than direct sequencing through the validation of pancreatic cell lines. Peptide nucleic acid-mediated PCR clamping detected KRAS mutations in 47.2% of 72 PDACs. Low tumor cellularity and low PCR amplification efficiency led to be undetected or failed by direct sequencing in pancreatic paraffinized samples.KRAS mutations were an independent worse prognostic factor predicting a reduced progression-free survival rate in the postoperative chemotherapy group. Peptide nucleic acid clamp real-time PCR was a sensitive method for detecting KRAS status in paraffinized PDAC samples. We identified a low KRAS mutation rate among the Korean PDAC patients using PNA clamp real-time PCR, potentially implicating epidemiological characteristics. The low KRAS mutation rate and its prognostic role may suggest the further survival benefit in Korean PDAC patients.

Detection of K‐ras gene mutation by liquid biopsy in patients with pancreatic cancer

Cell-free circulating tumor DNA (ctDNA) in serum has been considered to be a useful candidate for noninvasive cancer diagnosis. The current study was designed to estimate the clinical usefulness of genetic analysis for ctDNA by digital polymerase chain reaction in patients with pancreatic cancer. The authors compared K-ras mutations detected in endoscopic ultrasound-guided fine-needle aspiration biopsy tissue DNA and in ctDNA from 75 patients with pancreatic cancer. K-ras mutations in the serum of 66 independent, consecutive patients with pancreatic cancer were also analyzed and the authors compared the results with survival rates. The frequencies of the mutations in tissue samples at G12V, G12D, and G12R in codon 12 were 28 of 75 samples (37.3%), 22 of 75 samples (29.3%), and 6 of 75 samples (8.0%), respectively. Conversely, the rates of the mutations in ctDNA were 26 of 75 samples (34.6%), 29 of 75 samples (38.6%), and 4 of 75 samples (5.3%), respectively. Overall, the K-ras mutation rates in tissue and ctDNA were 74.7% and 62.6%, respectively, and the concordance rate between them was 58 of 75 samples (77.3%). Survival did not appear to differ by the presence of K-ras mutations in tissue DNA, but the survival of patients with K-ras mutations in ctDNA was significantly shorter than that of patients without mutations in both a development set (P = .006) and an independent validation set (P = .002). The difference was especially evident in cases with a G12V mutation. Analysis of ctDNA is a new useful procedure for detecting mutations in patients with pancreatic cancer. This noninvasive method may have great potential as a new strategy for the diagnosis of pancreatic cancer as well as for predicting survival.

KRAS in pancreatic cancer.

Pancreatic cancer is one of the most feared malignancies. The most common form of pancreatic cancer is adenocarcinoma arising from the ductal epithelium. KRAS is the most common oncogene that has been found to be mutated. However, targeting KRAS directly has been difficult. We do not know a lot about the relationship between KRAS and other signaling pathways. At the same time, little is known about the non KRAS mutated or wild type (WT) tumors. Most of the data that we have as far, as mutational status is concerned, has been obtained from the tumor itself and not from metastatic lesions. In this review, we discuss two abstracts (Abstracts #e15214 and #e15207) published in conjunction with the 2014 ASCO Annual Meeting. These discuss the relationship between KRAS and other signaling pathways and the differences between mutated KRAS and WT tumors. The studies found low rate of KRAS mutation in cells obtained from ascitic fluid. While the studies are small, these are novel findings that are worth exploring further. They increase our understanding of the biology of the disease and take us a step closer to treating this deadly malignancy.

Tumor profiling of biliary tract carcinomas to reveal distinct molecular alterations and potential therapeutic targets.

285 Background: Extrahepatic cholangiocarcinoma (EHCC), intrahepatic cholangiocarcinoma (IHCC), and gallbladder carcinoma (GBCA) are rare tumors with poor prognosis that tend to be chemo-resistant. The underlying molecular alterations and their correlation with altered responses to therapies are not well understood. We hypothesized that delineation of different molecular alterations in the cancer types might potentially yield different therapeutic options. Methods: 815 cases (126 EHCC, 434 IHCC, 244 GBCA, 11 NOS) were tested by a commercial multiplatform profiling service (Caris Life Sciences, Phoenix, AZ). Tests included sequencing (Sanger, NGS), gene amplification (CISH/FISH), and protein expression (IHC). Results: 24 of 47 genes tested had mutations, with the highest rates in TP53 (28%), KRAS (18%), IDH1 (9%), and SMAD4 (6%). BRCA1/2 mutations were seen in 3/41 (7.3%) and 5/40 (12.5%) cases. Overall,IHC showed high TOPO1, TOP2A, PD-1, SPARC and PD-L1 in 56%, 49%, 40%, 39% and 15% of cases and low RRM1, ERCC1 and TS in 82%, 72% and 79%, respectively, suggesting potential utility of chemotherapeutic and immunomodulatory agents targeting these alterations in selected cases. Mutually exclusive protein loss of chromatin modifiers BAP1 and PBRM1 were seen in 17% and 27%. ROS1 break-apart FISH showed negative results in 16 cases tested. Comparing the three carcinomas (EHCC, IHCC and GBCA, Table), EHCC had the highest KRAS mutation rate; IHCC had the highest IDH1 mutation; GBCA and EHCC had significantly higher TP53 mutation and HER2 amplification than IHCC.IDH1 and TP53 mutations were mutually exclusive, and IDH1-mutated IHCC had higher P-glycoprotein expression than TP53-mutated IHCC (82% vs. 37%). GBCA had high TOP2A by FISH and IHC, and a high loss of PBRM1(all p&lt;0.05). Conclusions: Multiplatform cancer profiling reveals distinctbiomarker characteristics of biliary tract carcinomas, offering insights into disease biology and suggests potential sensitivity to novel and conventional therapies. Further analyses with clinical correlation are warranted. [Table: see text]

EGFR and KRAS mutations in pulmonary pleomorphic carcinoma and their correlation with clinicopathologic features.

Aim of the studyPulmonary pleomorphic carcinoma (PPC) of the lung is a subset of poorly differentiated non-small cell lung cancers (NSCLCs). Because of its rarity, information on epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma viral oncogene (KRAS) mutations is controversial and sparse. The aim was to investigate the two key oncogenes’ characteristics and their correlation with clinical variables.Material and methodsWe retrospectively screened 110 paraffin-embedded surgically resected specimens from patients with PPC. Of these, follow-up information was available for 48 patients. We then successfully analyzed 70 PPC samples and examined EGFR and KRAS mutation status by direct sequencing. The findings were correlated with a control group of patients with other NSCLCs.ResultsIn our department, PPC comprised about 1.57% of surgical resected cases (110/6990). 37.4% of patients smoked. EGFR mutations were detected in 11 cases (15.7%), with a significantly higher frequency in women than men (p = 0.011). KRAS mutations were detected in 10 cases (14.3%) and were more often found at age 65 or older (p = 0.02). Of interest, in PPC, all KRAS mutations occurred in never smokers. Also, most never smokers have transversion mutations (G→T) in PPCs and other NSCLCs.ConclusionsOur results demonstrated a similar EGFR and KRAS mutation rate in Chinese PPC patients. EGFR tyrosine kinase inhibitors may be a treatment option for PPCs with EGFR mutations. Of note, EGFR mutations in PPC were commonly identified in women; therefore women should be high-priority candidates for mutation screening.

Recurrent Invasive Pulmonary Mucinous Adenocarcinoma Showing Responses to Platinum-Based Chemotherapy Regimens with Docetaxel and Bevacizumab:A Case Report

The primary pulmonary mucinous adenocarcinoma is a rare variety of lung cancer that accounts for 0.24% of all lung cancers [1]. Now it is defined as tumor cells with a goblet or columnar cell morphology with abundant intracytoplasmic mucin [2]. Usually, this type of mucinous neoplasm has specific imaging findings and pathological morphology. And it is often described as a kind of neoplasm is recrudescent rapidly and resistant to radiotherapy and chemotherapy. So this tumor has a remarkably poor prognosis. Recently, some researchers reported that this tumor may have a low rate of EGFR mutation and a high rate of K-ras mutation and ALK rearrangement [3-5].These characteristics of molecular pathology may change the treatment status of the tumor.

Mutation profile of KRAS and BRAF genes in patients with colorectal cancer: association with morphological and prognostic criteria

KRAS and BRAF mutations are well-recognized molecular alterations during colorectal carcinogenesis, but there is little agreement on their effect on tumor characteristics. Therefore, we aimed to evaluate the distribution of the most common KRAS and BRAF mutations in Greek patients with colorectal cancer and their possible associations with clinical histopathological parameters. In this study, 322 and 188 colorectal carcinomas were used for the mutation analysis of KRAS (exon 2) and BRAF (exon 15) genes, respectively. The mutational status of both genes was evaluated by polymerase chain reaction and sequencing analysis. Although the overall frequency of KRAS mutations (36.6%) seemed to be similar to those reported for other populations, the rate of point mutations at codon 13 was significantly lower (12%) in Greek patients with colorectal cancer and associated with male gender (P < 0.05). Tumors with G>T codon 12 transversions and G>C transitions showed more frequent lymph node metastasis (P < 0.05, P < 0.005, respectively). The rate of KRAS mutations gradually decreased with increasing histological grade (P < 0.05), as opposed to BRAF mutations, which were strongly associated with poorly differentiated tumors (P < 0.005). Additionally, we found that the histological features of preexisting adenoma were associated with the absence of BRAF mutations, in contrast to KRAS (P < 0.05). Our data suggested that there seems to be a correlation between morphological criteria and discrete genetic pathways in colorectal carcinogenesis. Moreover, ethnic or geographic factors may have an impact on genetic background of colorectal carcinomas, and specific types of KRAS mutations may influence the metastatic potential of colorectal tumors.

Low Grade Serous Ovarian Carcinoma: from the molecular characterization to the best therapeutic strategy.

Low Grade Serous Ovarian Carcinoma, LGSOC, is certainly a rare disease, accounting for only a small proportion of all ovarian carcinomas, nevertheless in the last decade we have acquired many data about its molecular and clinical features and it has been largely accepted that it has distinct pathogenesis, genetic aberrations and clinical behavior compared to High Grade Serous Ovarian Carcinoma, HGSOC, which is the most common ovarian cancer histotype. A large number of series pointed out the high rate of KRAS and BRAF mutations in LGSOCs and Serous Borderline Tumors, SBLTs, in contrast with their rarity in HGSOC. Such finding, together with the recurrent observation of focus of LGSOC associated with areas of SBLT in the same lesion, led to abandon the traditional histology classification, defining three types of serous carcinomas, in favor of a new dualistic grading system which recognizes only LG and HG carcinomas corresponding to distinct tumorigenesis pathways, the former based on KRAS/BRAF mutations and alteration of the MAP/ERK signaling, the latter characterized by early genetic instability and wild type status of KRAS and BRAF. LGSOC shows favorable overall survival, compared to general ovarian cancer population, but worrying resistance to conventional treatments. MEK inhibitors are emerging as active agents and may well represent an effective therapeutic strategy in the near future.

Meta-analysis of Epidermal Growth Factor Receptor and KRAS Gene Status between Primary and Corresponding Metastatic Tumours of Non-small Cell Lung Cancer

The epidermal growth factor receptor (EGFR) and KRAS gene status in paired primary non-small cell lung cancer (NSCLC) and metastatic tumours has been investigated by many studies, but remains controversial. We systematically reviewed studies in English of EGFR and KRAS gene status in primary and corresponding metastatic NSCLC up to 15 January 2014. Studies were selected rigorously from PubMed, EMBASE, as well as Cochrane Library databases. We carried out a meta-analysis to clarify EGFR mutations, EGFR amplification, positive rate of EGFR protein expression and KRAS mutations in primary and corresponding metastatic NSCLC. Our data suggested that the overall EGFR mutation rate, gene copy number, protein expression were not different between primary tumours and corresponding metastases, with the pooled odd ratios and 95% confidence interval 1.043 (0.686–1.586, P = 0.844), 0.604 (0.355–1.027, P = 0.063) and 1.447 (0.948–2.208, P = 0.087), respectively. The overall KRAS mutation rate of primary tumours was not different from that of matched metastases, with the odds ratio and 95% confidence interval being 1.224 (0.808–1.856, P = 0.340). The discordant rates of EGFR and KRAS mutations in paired primary and metastatic NSCLC were 14.5 and 16.7%, respectively. Among the discordant gene mutations in primary and metastatic lesions, the frequency of occurrence of mutation was not different from the frequency of loss of mutation for EGFR (P = 0.093) and KRAS gene (P = 0.227). These results indicate that EGFR and KRAS mutations are present frequently in metastases and occur before metastasis. Therefore, routine analysis of EGFR or KRAS gene status both in primary and metastatic tumours is not recommended.

Comparison of PNA clamping and direct sequencing for detecting KRAS mutations in matched tumour tissue, cell block, pleural effusion and serum from patients with malignant pleural effusion.

Peptide nucleic acid (PNA)-mediated real-time polymerase chain reaction clamping was recently developed to improve mutation detection sensitivity. Pleural effusion could be a good sample candidate for mutation analysis. To establish if PNA clamping could be used to detect KRAS mutation in particular in pleural effusion, we analysed its diagnostic performance. We studied 57 patients with malignant effusion. KRAS mutation was evaluated in samples of matched tumour tissue, cell block, pleural effusion and serum using PNA clamping and direct sequencing. The detection rate of KRAS mutation using pleural effusion was 14% for PNA clamping and 10.5% for direct sequencing. The κ coefficient between the two methods was 0.76 (P value < 0.0001), 1.00 (P value < 0.0001) and 0.87 (P value < 0.0001) in pleural effusion, tissue and cell block, respectively. The diagnostic performance of KRAS mutation detection from pleural effusion compared with the results obtained for all samples combined showed that the sensitivity, specificity, positive predictive value and negative predictive value were as follows: 89, 100, 100 and 98%, respectively for PNA clamping; 67, 100, 100 and 94%, respectively for directing sequencing. The current study suggests that PNA clamping had a good concordance with direct sequencing for the detection of KRAS mutation in patients with malignant effusion. Furthermore, the good diagnostic performance obtained from pleural effusion samples provides evidence that pleural effusion can be a useful source for detecting KRAS mutation in a clinical setting, in which the collection of tumour tissues is challenging.

Abstract 2231: The prevalence of EGFR and KRAS mutations in a population of African immigrants in France is closer to that of Asian populations than to white Europeans

Abstract The choice of treatment for patients with NSCLC relies on the EGFR and KRAS mutational status. Previous studies have reported differences in prevalence of mutations between Asiatics, Hispanics and Caucasians. However, there is few data with respect to the frequencies of EGFR and KRAS mutations in patients originated from Africa, who represent the largest immigrant population in France. Between May 2011 and November 2013, a mutational analysis for KRAS and EGRF has been performed in tumor samples from 1,973 consecutive patients with NSCLC at a single oncogenetic platform. Demographic and clinical data of all these patients were extracted from their electronic medical record and analyzed. Our study population included 1,739 (88%) white Europeans, 204 (10%) patients from Africa and 30 (2%) patients from Asia (mostly from Vietnam or Cambodge). As expected, the higher prevalence of EGFR mutations was found in Asiatic women (50%), the lower was observed in Caucasian women population (17%, p&amp;lt;0.001). This low frequency of EGFR mutations has already been reported in other European populations. Surprisingly, EGFR mutations rate was as high as 32% in African women patients (p&amp;lt;0.001), whereas African men exhibited a very low frequency of EGFR mutations (5%, p&amp;lt;0.001) as well as the French non immigrant patients (6%). KRAS mutation rate was higher among white European (26%) than Asiatic (10%) or African (10%) patients. Although KRAS mutation rate did not differ by sex in white Europeans (men 25% versus women 27%, respectively), it was 3 fold more frequent in men than in women among African (19% versus 5%, respectively, p&amp;lt;0.001) and Asiatic patients.Therefore EGFR or KRAS mutation rates in African immigrant population in France are closer to those observed in Asians or even Hispanics, than in Caucasians. These frequencies also differ from those reported in African Americans. The ancestral and recent migration of populations as well as social habits could explain these results. Citation Format: Antoinette Lemoine, Raphael Saffroy, Nelly Bosselut, Emmanuel Lecorche, Reza Etessami, Marc A. Allard, Jean Tredaniel, Andre Balaton, Pierre Validire, Jean F. Morere. The prevalence of EGFR and KRAS mutations in a population of African immigrants in France is closer to that of Asian populations than to white Europeans. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2231. doi:10.1158/1538-7445.AM2014-2231

Abstract LB-14: Polyisoprenylated cysteinyl amides as targeted small molecule anti-Ras therapies

Abstract Pancreatic cancer harbors the highest reported rates of K-Ras mutations, lacks effective therapies and is the most challenging to treat. It is thus the most deadly neoplasm with a 5-year survival rate of only 6%. We reveal here that polyisoprenylated methylated protein methyl esterase (PMPMEase) is overexpressed in 93% of pancreatic duct adenocarcinoma. We further present novel compounds with the potential to serve as effective targeted therapies for pancreatic and other cancers with hyperactive growth signaling pathways mediated by Ras and related G-proteins. The design and synthesis of the polyisoprenylated cysteinyl amide inhibitors (PCAIs) of PMPMEase incorporate three key elements to obtain compounds to selectively disrupt polyisoprenylation-mediated protein-protein interactions; the farnesyl group for high affinity interactions, a substituted amide bioisostere of the scissile ester bond of the endogenous substrates and an ionizable appendage group designed to mitigate the excessive hydrophobicity of the farnesyl cysteinyl amide that constitutes the pharmacophore. The PCAIs inhibited PMPMEase with Ki values ranging from 3.7 to 20 μM. The 48 h EC50 values for pancreatic cancer Mia PaCa-2 and BxPC-3 cell lines were as low as 1.9 μM while Salirasib (farnesylthiosalicylic acid, FTS) and farnesylthiosalicylamide were not effective even at 20 μM. The PCAIs thus have the potential to serve as a novel class of targeted therapies for cancers with hyperactive G-proteins and the growth factor receptors whose signals they transmit. Citation Format: Nazarius S. Lamango, Byron J. Aguilar, Augustine T. Nkembo, Randolph Duverna, Felix Amissah, Rosemary A. Poku, Seth Y. Ablordeppey. Polyisoprenylated cysteinyl amides as targeted small molecule anti-Ras therapies. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-14. doi:10.1158/1538-7445.AM2014-LB-14

Gene Mutation Analysis in Non-Small Cell Lung Cancer Patients using Bronchoalveolar Lavage Fluid and Tumor Tissue as Diagnostic Markers

Non-small cell lung cancer (NSCLC) is one of the main causes of cancer death in the world. Early detection of NSCLC can improve its outcome. The aim of this study was to identify the mutations of the KRAS and p53 genes in bronchoalveoar lavage (BAL) fluid for the early detection of peripheral NSCLC. We examined the DNA obtained from the tumor, nearby normal lung tissue, and matched BAL fluid for mutations in the KRAS and p53 genes; the material was obtained from 48 patients with peripheral NSCLC, and was analyzed by PCR-single strand conformation polymorphism and DNA sequencing. BAL fluids from 26 patients with benign lung disease were used as controls. Positive rates of KRAS and p53 mutations were distributed as follows: in NSCLC tissue, 52% and 58%; in BAL fluid of NSCLC patients, 38% and 44%; in normal lung tissue, 6% and 4%; and in BAL fluid of patients with benign lung disease, 8% and 4%. The combined detection of both KRAS and p53 mutations yielded a sensitivity of 66% for the diagnosis of peripheral NSCLC, which is markedly higher than that of cytology plus histology by first bronchoscopy (38%, p=0.008). In each patient with the 2 gene mutations in BAL fluid, mutation type and location were the same as those of the primary tumor. Our study indicates that the detection of the KRAS and p53 mutations in BAL fluids could be a helpful addition to cytology and histology examination for the diagnosis of peripheral NSCLC.

Detection of KRAS gene mutations in colorectal carcinoma: a study of 6 364 patients

To investigate the mutation rate and types of KRAS gene in colorectal carcinoma of Chinese patients, and to document the regional distribution of the mutation. A total of 6 364 colorectal carcinoma tumor specimens were obtained from 27 provinces and autonomous regions in China from 2009 to 2013. Pyrosequencing was used to detect mutations in codons 12 and 13 of KRAS gene. The mutation types of KRAS and the difference of regional distribution were statistically analyzed. KRAS mutation rate in Chinese colorectal carcinoma patients was 37.43 % (2 382/6 364). Ten types of single-base mutations of KRAS codons 12 and 13 were detected, including six common types: 12GGT > GAT (14.77%), 13GGC > GAC (8.19%), 12GGT > GTT (7.89%), 12GGT > TGT (2.20%), 12GGT > AGT (2.00%), and 12GGT > GCT (1.48%). Other four less occurring mutation types (<1%) included 12GGT > CGT, 13GGC > TGC, 13GGC > CGC, and 13GGC > AGC. In addition, 8 other mutation types were identified in 13 tumor samples. The rates of KRAS mutation in patients from different regions were between 35.68% and 38.04% and no significant differences were observed (P > 0.05). Abundant mutation types of KRAS gene exist in colorectal cancers among Chinese patients. The six common mutation types occur with a frequency of not less than 1%. There are no significant differences of KRAS mutation rate among Chinese patients from various areas. Pyrosequencing provides a rapid and accurate method of KRAS mutation detection for clinical application.

216P - Circulating Free Dna and Plasma Kras Mutations in Metastatic Colorectal Cancer Patients Treated with Bi-Weekly Cetuximab and Irinotecan

ABSTRACT Aim: Small fractions of cell-free DNA (cfDNA) can be quantified from blood samples, is a mixture of DNA from malignant and normal cells, and can be used as a liquid biopsy to detect and quantify tumor specific hotspot mutations such as KRAS. We investigated the total cfDNA and the tumor specific circulating DNA with KRAS mutations in plasma from patients with metastatic colorectal cancer (mCRC) treated with third line cetuximab and irinotecan. Methods: Patients with histopathologically verified mCRC and adequate PS and organ function were included. All patients were resistant to 5-FU, oxaliplatin and irinotecan and treated with 3rd line irinotecan (180 mg/m2) and cetuximab (500 mg/m2) every second week in a prospective phase II study until disease progression or unacceptable toxicity. Plasma was obtained from a pre-treatment EDTA blood-sample, and the total cfDNA and plasma mutations were quantified by an in-house qPCR method. Quantitative levels of cfDNA were analyzed in relation to clinical data, and to tumor volume as estimated from pretreatment PET-CT. Results: Ninety-five patients were included. There was a significantly higher PFS and OS in patients with low levels of cfDNA, and decreasing median survival with increasing number of alleles. The OS in patients with total cfDNA in the lowest quartile was 17,0 months (95% CI 12.7 -19,8 months ) and 12,1 months (9.6–13,4 ), 9,2 months (6,9 -14,0) and 6,9 months (4,3–8,6) in the higher, respectively (p = 0.0001). The HR for patients with cfDNA levels above the 75% quartile indicated a strong detrimental effect on survival in this group of patients. The rate of tumor KRAS mutation (Exon 2) in this cohort was 34%, and a total of 30 patients had detectable plasma KRAS mutations. The levels of total cfDNA and tumor KRAS mutational alleles in the plasma were strongly correlated (spearman rank 0.88, p = 0.0001). Studies investigating the correlation of both total cfDNA and number of mutated alleles to tumor volume as estimated from PET-CT scans are on-going. Conclusions: The present study confirms a strong prognostic value of circulating DNA, and correlation between tumor and plasma KRAS. The results of relation to tumor volume will be presented at the meeting. Disclosure: All authors have declared no conflicts of interest.