KRAS Wild-type Group Research Articles

Exploratory biomarker analysis for predicting treatment effects of aflibercept in the VELOUR trial.

3592 Background: Second-line treatment with aflibercept and FOLFIRI in patients with metastatic colorectal carcinoma (mCRC) previously treated with oxaliplatin improved overall survival (OS) versus placebo [Hazard ratio (HR), 0.81; 95% CI, 0.71–0.93; P=0.003]1. However, colorectal cancer (CRC) is a heterogenous disease and the new intrinsic consensus molecular (iCMS) allows for tumours to be subtyped into unique genetic and transcriptional features2. We present a post hoc analysis of VELOUR patient data, to assess the impact of KRAS or BRAF mutation status and iCMS on efficacy parameters. Methods: Patient samples were classified as either KRAS or BRAF mutant or wild-type (WT) via a targeted mutation panel1. Gene expression data was used to classify samples as either iCMS2 or iCMS3 using a modified classifier based on iCMS signatures which are specifically up-regulated in tumour samples2. Results: Of the 439 patients with available RNA data, 54.9% (241/439) were classified as iCMS2; 45.1% (198/439) as iCMS3; 48.3% (212/439) as RAS mutant and 8.4% (37/439) as RAF mutant. A favourable aflibercept treatment effect was observed for patients within the KRAS WT group (Median OS from 11 to 17.7 months; HR 0.87; 95% CI 0.79-0.96, P=0.005), particularly for patients with KRAS WT iCMS2 tumours (Median OS from 15.5 to 30.4 months; HR 0.81; 95% CI 0.70-0.94, P=0.004). This is in comparison to the KRAS WT iCMS3 patients where no treatment benefit was seen (HR 0.97; 95% CI 0.82-1.14, P=0.683). In addition, no treatment benefit was seen in the KRAS mutant group (OS HR 1.03; 95% CI 0.96-1.12, P=0.405). Progression-free survival (PFS) data followed the same trend. Aflibercept seemed to also strongly benefit the 37 patients with BRAF-mutated tumours, (PFS HR 0.46, 95% CI 0.20-1.09; OS HR 0.65, 95% CI 0.29-1.48), although differences were not statistically significant. Irrespective of treatment, improved OS (HR 0.60; 95% CI 0.48-0.75, P< 0.001) and PFS (HR 0.75; 95% CI 0.60-0.94, P=0.011) were observed in all patients with iCMS2 versus iCMS3 tumours, as expected. Treatment-by-mutation status interaction tests (OS P=0.40, PFS P=0.33) indicated that the aflibercept benefit was not statistically different among the mutation sub-groups, although the small sample size limited the analysis. Conclusions: In the VELOUR study, the benefit of the addition of aflibercept to FOLFIRI appears to be primarily in patients with KRAS WT tumours, especially those with KRAS WT iCMS2. The improved OS and PFS seen in all patients with iCMS2 tumours in comparison to iCMS3 is prognostic but not predictive of aflibercept treatment response in addition to FOLFIRI. On the contrary, the addition of aflibercept to FOLFIRI provided a numerical benefit in BRAF-mutated tumours, however the P-values were not statistically significant.

Real-world impact of KRAS mutations on clinical outcomes in metastatic colorectal cancer treated with trifluridine-tipiracil in the USA.

e15566 Background: Defining the impact of KRAS mutation status on outcomes to standard of care treatments in metastatic colorectal cancer (mCRC) is of increasing clinical relevance. We interrogated a large real-world genomic database to further explore the association between KRAS mutations and benefit to trifluridine-tipiracil (FTD-TPI) in patients with mCRC. Methods: 19,364 patients with mCRC and known KRAS mutation status were analyzed by next-generation sequencing (NextSeq, 592 Genes; NovaSeq, whole exome sequencing (WES)) at Caris Life Sciences. Real-world overall survival (rwOS) and time on treatment (ToT) was inferred from insurance claims data and calculated from time of start of treatment with FTD-TPI to last contact and time from first to last treatment with FTD-TPI with comparison done by the Kaplan-Meier test, respectively. Chi-square test was applied where appropriate, with p-value adjusted for multiple comparisons (p < 0.05). Results: 764 of 10,571 (7.2%) patients with wild-type (WT) KRAS, 768 of 6,984 (11%) with KRAS G12 mutation, and 170 of 1,809 (9.4%) with KRAS G13 mutation received FTD-TPI. Age distribution was similar among groups. Sidedness of primary site was reported in 692 (40.3%) patients; an increased proportion of right-sided tumors was observed in KRAS G12 (53.4% vs. 28.3%, p < 0.0001) and G13 (56% vs 28.3%, p < 0.0001) groups compared to KRAS WT. An increased proportion of TP53 mutations in KRAS WT was observed compared to KRAS G12 mutation (87% vs. 70%, p < 0.0001) and KRAS G13 mutation groups (87% vs. 75%, p < 0.0001). KRAS G12 mutation was associated with shorter median rwOS compared to KRAS WT (7.33 vs. 8.43 months (mo), HR 1.13 (95% CI 1.11-1.42), p = 0.041). KRAS G13 mutation was associated with similar rwOS to KRAS WT. Median ToT was shorter in patients with KRAS G12 mutations than KRAS WT (1.8 vs. 2 mo, HR of 1.22 (95% CI 1.11-1.42), p < 0.001). Median ToT was longer in patients with KRAS G13 versus KRAS G12 (2.3 vs. 1.8 mo, HR 0.82 (95% CI 0.68-0.98), p = 0.032). Conclusions: To our knowledge, this is the largest primarily US-based cohort of mCRC treated with FTD-TPI to be reported. KRAS G12 mutation, but not KRAS G13 mutation, was associated with shorter rwOS and ToT compared to KRAS WT, despite enrichment of TP53 and BRAF mutations in the KRAS WT group. This finding is consistent with previously published analyses of large randomized prospective trials of FTD-TPI in mCRC and further support KRAS mutation status as a predictive biomarker in this setting. [Table: see text]

Fluoropyrimidine type, patient age, tumour sidedness and mutation status as determinants of benefit in patients with metastatic colorectal cancer treated with EGFR monoclonal antibodies: individual patient data pooled analysis of randomised trials from the ARCAD database

BackgroundKRAS mutations in metastatic colorectal cancer (mCRC) are used as predictive biomarkers to select therapy with EGFR monoclonal antibodies (mAbs). Other factors may be significant determinants of benefit.MethodsIndividual patient data from randomised trials with a head-to-head comparison between EGFR mAb versus no EGFR mAb (chemotherapy alone or best supportive care) in mCRC, across all lines of therapy, were pooled. Overall survival (OS) and progression-free survival (PFS) were compared between groups. Treatment effects within the predefined KRAS biomarker subsets were estimated by adjusted hazard ratio (HRadj) and 95% confidence interval (CI). EGFR mAb efficacy was measured within the KRAS wild-type subgroup according to BRAF and NRAS mutation status. In both KRAS wild-type and mutant subgroups, additional factors that could impact EGFR mAb efficacy were explored including the type of chemotherapy, line of therapy, age, sex, tumour sidedness and site of metastasis.Results5675 patients from 8 studies were included, all with known mCRC KRAS mutation status. OS (HRadj 0.90, 95% CI 0.84–0.98, p = 0.01) and PFS benefit (HRadj 0.73, 95% CI 0.68–0.79, p < 0.001) from EGFR mAbs was observed in the KRAS wild-type group. PFS benefit was seen in patients treated with fluorouracil (HRadj 0.75, 95% CI 0.68–0.82) but not with capecitabine-containing regimens (HRadj 1.04, 95% CI 0.86–1.26) (pinteraction = 0.002). Sidedness also interacted with EGFR mAb efficacy, with survival benefit restricted to left-sided disease (pinteraction = 0.038). PFS benefits differed according to age, with benefits greater in those under 70 (pinteraction = 0.001). The survival benefit was not demonstrated in those patients with mutations found in the KRAS, NRAS or BRAF genes. The presence of liver metastases interacted with EGFR mAb efficacy in patients with KRAS mutant mCRC (pinteraction = 0.004).ConclusionThe benefit provided by EGFR mAbs in KRAS WT mCRC is associated with left-sided primary tumour location, younger patient age and absence of NRAS or BRAF mutations. Survival benefit is observed with fluorouracil but not capecitabine. Exploratory results support further research in KRAS mutant mCRC without liver metastases.

Correlations between Demographic, Clinical, and Paraclinical Variables and Outcomes in Patients with KRAS-Mutant or KRAS Wild-Type Metastatic Colorectal Cancer-A Retrospective Study from a Tertiary-Level Center in Romania.

Colorectal cancer (CRC) is a significant global public health concern and its characteristics in Eastern Europe are underexplored. In this retrospective study, data of 225 patients with metastatic colorectal cancer (mCRC) from the Colțea Clinical Hospital's Oncology Department in Bucharest were analyzed between 2015 and 2023. They were divided into two groups based on the presence of KRAS mutation. The primary objective of the study was to investigate whether the presence of KRAS mutations influenced the prognosis of mCRC and to identify any demographic, clinical, or paraclinical factors associated with KRAS mutations in stage IV CRC. The overall survival for the entire study population was 29 months. There was a trend towards increased survival in the KRAS wild-type group (31 months) compared to the KRAS-mutant group (26 months), but this difference did not reach statistical significance. We found that lower levels of education, advanced T stage, advanced N stage, and M1 stage at diagnosis negatively impacted prognosis. Real-world data are crucial in shaping public policy strategies to better support patients with metastatic CRC. Understanding the correlations between the demographic, clinical, and paraclinical variables and the outcomes in mCRC patients with KRAS-mutant and KRAS wild-type colorectal cancer is essential for improving patient care and treatment strategies in Romania and beyond.

Wild-Type KRAS Is Required for Panitumumab Efficacy in Patients With Metastatic Colorectal Cancer.

Panitumumab, a fully human antibody against the epidermal growth factor receptor (EGFR), has activity in a subset of patients with metastatic colorectal cancer (mCRC). Although activating mutations in KRAS, a small G-protein downstream of EGFR, correlate with poor response to anti-EGFR antibodies in mCRC, their role as a selection marker has not been established in randomized trials. KRAS mutations were detected using polymerase chain reaction on DNA from tumor sections collected in a phase III mCRC trial comparing panitumumab monotherapy to best supportive care (BSC). We tested whether the effect of panitumumab on progression-free survival (PFS) differed by KRAS status. KRAS status was ascertained in 427 (92%) of 463 patients (208 panitumumab, 219 BSC). KRAS mutations were found in 43% of patients. The treatment effect on PFS in the wild-type (WT) KRAS group (hazard ratio [HR], 0.45; 95% CI: 0.34 to 0.59) was significantly greater (P < .0001) than in the mutant group (HR, 0.99; 95% CI, 0.73 to 1.36). Median PFS in the WT KRAS group was 12.3 weeks for panitumumab and 7.3 weeks for BSC. Response rates to panitumumab were 17% and 0%, for the WT and mutant groups, respectively. WT KRAS patients had longer overall survival (HR, 0.67; 95% CI, 0.55 to 0.82; treatment arms combined). Consistent with longer exposure, more grade III treatment-related toxicities occurred in the WT KRAS group. No significant differences in toxicity were observed between the WT KRAS group and the overall population. Panitumumab monotherapy efficacy in mCRC is confined to patients with WT KRAS tumors. KRAS status should be considered in selecting patients with mCRC as candidates for panitumumab monotherapy.

The profile and prognostic value of circulating lymphocyte subsets in metastatic colon cancer.

Colon cancer (CC) are the most common malignant cancer in human digestive system, however, the profile and prognostic value of circulating lymphocyte subsets in CC patients has not been systemically clarified. In this study, 158 patients with metastatic CC were enrolled. Chi-square test was used to analyze the relationship between baseline peripheral blood lymphocyte subsets and clinicopathological parameters. Kaplan-Meier and Log-rank tests were used to analyze the relationship between clinicopathological parameters and baseline peripheral lymphocyte subsets and overall survival (OS) of patients with metastatic CC. Univariate/multivariate COX regression analysis was used to identify the independent factors in metastatic CC. The baseline peripheral blood CD3+T cells, CD4+T cells, NK cells and B cells of BRAF mutant patients were significantly lower than those in BRAF wild-type patients; The baseline CD8+T cells of KRAS mutation group was lower than that in KRAS wild type group. Peripheral blood CA19-9>27, left-sided colon cancer (LCC), KRAS and BRAF mutation were poor prognostic factors, and ALB>40, NK cells were protective prognostic factors for metastatic CC. In patients with liver metastases subgroup, higher NK cells also indicated a longer OS. Finally, LCC (HR=0.56), CA19-9 (HR=2.13), ALB (HR=0.46) and circulating NK cells (HR=0.55) were independent prognostic factors for metastatic CC. LCC, higher level of ALB and NK cells at baseline are protective factors, and higher CA19-9, KRAS/BRAF gene mutation are adverse prognostic factors. Sufficient circulating NK cells are independent prognostic factor for metastatic CC patients.

KRAS mutation as a predictor of insufficient trastuzumab efficacy and poor prognosis in HER2-positive advanced gastric cancer.

Although RAS and PIK3CA mutations have been associated with resistance to anti-EGFR antibody in colorectal cancer or trastuzumab in breast cancer, their implications for trastuzumab resistance in HER2-positive advanced gastric cancer (AGC) remains unclear. We aimed to assess the relationship between trastuzumab efficacy and mutation status in the HER family signaling pathway. This study retrospectively evaluated patients with HER2-positive AGC who received first-line trastuzumab-containing chemotherapy between March 2011 and November 2015. Multiplex genotyping, including KRAS, NRAS, PIK3CA, and BRAF, was then performed using the Luminex Assay, after which KRAS amplification was measured using quantitative real-time reverse transcription-polymerase chain reaction. Thereafter, the association between genetic alterations and clinical outcomes were evaluated. KRAS mutation (MT) was detected in 6 of 77 patients (7.8%), whereas KRAS amplification was found in 15 of 67 patients (22%). No mutations in NRAS, PIK3CA, or BRAF were identified. The KRAS MT group showed significantly worse response rates (16.7% vs. 66.2%, P = 0.016), progression-free survival [median, 4.8 vs. 11.6months; hazard ratio (HR), 3.95; 95% CI, 1.60-9.76; P = 0.0029], and overall survival (11.5 vs. 23.6months; HR, 3.80; 95% CI, 1.56-9.28; P = 0.033) compared to the KRAS wild-type group. KRAS amplification had no effect on clinical outcomes. KRAS mutation was an independent prognostic factor for poor survival and might predict insufficient trastuzumab efficacy, whereas KRAS amplification showed no prognostic significance during trastuzumab treatment. Further investigations are warranted to confirm the predictive value of KRAS status in HER2-positive AGC.

Anti-HER2 therapy with pyrotinib and trastuzumab in refractory HER2-positive metastatic colorectal cancer: A preliminary report from HER2-FUSCC-G study.

97 Background: Dual-targeted HER2 therapy has led to a promising antitumor effect in HER2 positive metastatic colorectal cancer. The current study was aimed to evaluate the therapeutic efficacy of pyrotinib and trastuzumab in patients with HER2 positive colorectal cancer. Methods: HER2-FUSCC-G is an ongoing, open-label, non-randomised, phase 2a study. Patients in this subset were diagnosed as HER2 positive metastatic colorectal cancer refractory to standard chemotherapies. All the enrolled patients were treated with a loading dose of trastuzumab at 8 mg/kg followed by 6mg/kg once every three weeks, and oral pyrotinib at 400 mg per day until progression. ORR was set as the primary endpoint. Estimates of PFS (progression free survival) and OS (overall survival) were obtained with the Kaplan-Meier method and compared with log-rank test. Results: Between January 2020 to June 2021, 11 patients were enrolled in this study. The ORR was 45.5% in whole population, and 55.6% in RAS wild-type patients. At a median follow-up of 17.73 months, median PFS and OS were 7.80 and 14.97 months, respectively. The KRAS wild-type group of patients had prolonged survival (PFS: 9.97 vs. 7.73 months, P = 0.19; OS: 20.67 vs. 12.43 months, P = 0.021) compared with KRAS mutant group. Nine of 11 (81.8%) patients reported≥1 grade treatment-emergent adverse events (TATEs), while 4 (36.4%) patients reported grade 3/4 TATEs. Conclusions: The combination of trastuzumab and pyrotinib showed a promising anti-tumor response and prolonged long-term survival benefit in RAS wild-type and HER2 positive mCRC with acceptable tolerance. Clinical trial information: NCT04960943.

Diameter of Superior Rectal Vein - CT Predictor of KRAS Mutation in Rectal Carcinoma.

BackgroundThe purpose of this study was to investigate the feasibility of CT parameters to predict the presence of KRAS mutations in rectal cancer patients. The relationship between the presence of a KRAS mutation and pathological findings was evaluated simultaneously.MethodsEighty-nine patients (29 females, 60 males, age 27–90, mean 59.7±12 years) with pathologically proven rectal cancer were enrolled. A KRAS mutation test was completed following surgery. Parameters evaluated on CT included the tumor location, the diameter of the superior rectal vein (SRV) and inferior mesenteric vein (IMV), the presence of calcification, ulceration, lymph node enlargement (LNE), distant metastasis, tumor shape (intraluminal polypoid mass, infiltrative mass, or bulky), circumferential extent (C0–C1/4, C1/4–C1/2, C1/2–C3/4, or C3/4–C1), enhanced pattern (homogeneous or heterogeneous), CT ratio, and the length of the tumor (LOT). Pathological findings included lymphovascular emboli, signet ring cell, peripheral fat interval infiltration, focal ulcer, lymph node metastasis, tumor pathological type, and differentiation extent. The correlations between KRAS status and CT parameters, and KRAS status and pathological findings were investigated. The accuracy of CT characteristics for predicting KRAS mutation was evaluated.ResultsA KRAS mutation was detected in 42 cases. On CT image, the diameter of the SRV was significantly increased in the KRAS mutation group compared to in the KRAS wild-type group (4.6±0.9 mm vs 4.2±0.9 mm, p=0.02), and LNE was more likely to occur in the KRAS mutation group (73.3% vs 26.7%, p=0.03). There was no significant difference between the KRAS mutation group and the KRAS wild-type group on the other CT parameters (location, IMV, calcification, ulcer, distant metastasis, tumor shape, enhanced pattern, circumferential extent, CT ratio, and LOT). In the pathological findings, a KRAS mutation was more likely to occur in the middle differentiation group (p=0.03). No significant difference was found between the KRAS mutation group and the KRAS wild-type group in the presence of lymphovascular emboli, signet ring cell, peripheral fat interval infiltration, focal ulcer, lymph node metastasis, and tumor pathological type. With the best cut-off value of 4.07 mm, the AUC of the SRV to predict a KRAS mutation was 0.63 with a sensitivity of 76.2% and a specificity of 48.9%.ConclusionIt was feasible to use the diameter of the SRV to predict a KRAS mutation in rectal cancer patients, and LNE also can be regarded as an important clue on preoperative CT images.

Development of a dual-energy spectral CT based nomogram for the preoperative discrimination of mutated and wild-type KRAS in patients with colorectal cancer

PurposeTo develop a dual-energy spectral CT (DESCT) nomogram for the preoperative identification of KRAS mutation in patients with colorectal cancer (CRC). MethodOne hundred and twenty-four patients who underwent energy spectrum CT pre-operatively were recruited and split into mutated KRAS group (n = 50) and wild-type KRAS group (n = 74). DESCT parameters, including monochromatic CT value, iodine concentration, water concentration, and effective atomic number were measured independently by two reviewers in the arterial, venous, and delayed phases. Normalized iodine concentration (NIC) and slope k of the spectral HU curve were calculated. Evaluate other imaging features such as ATL/LTL ratio, tumor gross pattern, pericolorectal fat invasion (PFI) was also performed by these reviewers. Independent predictors for KRAS mutation were screened out using logistic regression, and these predictors were presented as a nomogram. The receiver operating characteristic (ROC) curve, calibration curve and decision curve analysis (DCA) were used to evaluate the clinical usefulness of the nomogram. ResultsThe slope k in the arterial phase, effective atomic number in the arterial phase, NIC in the venous phase, ATL/LTL ratio and PFI were significant independent predictors for KRAS mutation. Based on these independent predictors, a quantitative nomogram was developed to predict individual KRAS mutation probability. The nomogram had excellent performance with an AUC of 0.848 and excellent calibration. DCA showed that our nomogram has outstanding clinical utility. ConclusionsThis study demonstrates that a DESCT based nomogram has potential value for individual preoperative identification of KRAS mutation in CRC patients.

Characterizing MRI features of rectal cancers with different KRAS status

BackgroundTo investigate whether MRI findings, including texture analysis, can differentiate KRAS mutation status in rectal cancer.MethodsTotally, 158 patients with pathologically proved rectal cancers and preoperative pelvic MRI examinations were enrolled. Patients were stratified into two groups: KRAS wild-type group (KRASwt group) and KRAS mutation group (KRASmt group) according to genomic DNA extraction analysis. MRI findings of rectal cancers (including texture features) and relevant clinical characteristics were statistically evaluated to identify the differences between the two groups. The independent samples t test or Mann-Whitney U test were used for continuous variables. The differences of the remaining categorical polytomous variables were analyzed using the Chi-square test or Fisher exact test. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminatory power of MRI features. The area under the ROC curve (AUC) and the optimal cut-off values were calculated using histopathology diagnosis as a reference; meanwhile, sensitivity and specificity were determined.ResultsMean values of six texture parameters (Mean, Variance, Skewness, Entropy, gray-level nonuniformity, run-length nonuniformity) were significantly higher in KRASmt group compared to KRASwt group (p < 0.0001, respectively). The AUC values of texture features ranged from 0.703~0.813. In addition, higher T stage and lower ADC values were observed in the KRASmt group compared to KRASwt group (t = 7.086, p = 0.029; t = − 2.708, p = 0.008).ConclusionThe MRI findings of rectal cancer, especially texture features, showed an encouraging value for identifying KRAS status.

Preoperative metabolic tumor volume of intrahepatic cholangiocarcinoma measured by 18F-FDG-PET is associated with the KRAS mutation status and prognosis

BackgroundSurgical resection remains the mainstay of curative treatment for intrahepatic cholangiocarcinoma (ICC). Prognosis after surgery is unsatisfactory despite improvements in treatment and post-operative clinical management. Despite developments in the molecular profiling of ICC, the preoperative prediction of prognosis remains a challenge. This study aimed to identify clinical prognostic indicators by investigating the molecular profiles of ICC and evaluating the preoperative imaging data of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET).MethodsA retrospective analysis was performed on 50 consecutive patients with ICC who underwent curative hepatectomy after 18F-FDG-PET examination. To evaluate the molecular profiles of ICC, KRAS mutation status was assessed in resected specimens. For the assessment of glucose uptake, we observed the expression of glucose transporter-1 (GLUT-1) by immunohistochemistry. The data of 18F-FDG-PET were re-evaluated as follows: maximum standardized uptake value, metabolic tumor volume (MTV), and total lesion glycolysis (TLG). Cut-off values were determined using receiver operating characteristic (ROC) curve analysis. Cumulative overall survival (OS) was analyzed using the Kaplan–Meier analysis.ResultsOverall, 16 (32.0%) patients had mutations in KRAS. Patients with mutated KRAS exhibited shorter OS than those with wild-type KRAS (5-year OS, 0% vs. 35.1%, P < 0.001). GLUT-1 expression was significantly higher in tumors with mutated KRAS than in tumors with wild-type KRAS (median, 4.0 vs. 1.0, P < 0.001). Survival was significantly different when stratified by expression of GLUT-1 (5-year OS, 0% vs. 46.5%, P <0.001). Among the 18F-FDG-PET parameters, the MTV and TLG were significantly higher in the mutated KRAS group than in the wild-type KRAS group (P = 0.013 and P = 0.026, respectively). ROC curve analysis revealed a cut-off value of 38 for the MTV, with the highest accuracy (area under the curve = 0.789; 95% confidence interval, 0.581–0.902) for predicting KRAS mutation. This cut-off value permitted stratification of OS (high vs. low: 5-year OS, 13.1% vs. 36.7%, P = 0.008).ConclusionsHigh MTV is associated with KRAS mutation and poor postoperative outcomes in patients with ICC, suggesting that the MTV of ICC measured by 18F-FDG-PET may provide useful information for tumor molecular profiles and prognosis.

KRAS mutation associated with CD44/CD166 immunoexpression as predictors of worse outcome in metastatic colon cancer.

Multiple stages of carcinogenesis in colon cancer encompass subpopulations of cancer stem cells (CSC), responsible for tumor cell transformation, growth and proliferation. CD44 and CD166 proteins are CSC markers associated with cell signaling, adhesion, migration, metastasis and lymphocytic response. The expression of CSC may be modulated by some factors, such as the KRAS gene mutation. Correlate the expression of CD44 and CD166 markers in metastatic colon adenocarcinoma and KRAS mutation status (wild-type/mutated) with clinical pathological features and patients' outcome. Fifty-eight samples of tumor tissue samples of metastatic colon adenocarcinoma were collected from patients treated with CapeOx at the HCFMRP-USP Clinical Oncology Service. Clinical and survival data were collected from medical records. KRAS status was determined by the polymerase chain reaction (PCR) technique, and analysis of immunohistochemical expression of CD44 and CD166 proteins was performed by tissue microarray. The expression of CD44 and CD166 were positive in 41% and 43% of patients, respectively, and mutated KRAS was detected in 48% of patients. A significant association was found between CD166 and CD44 expression (p= 0.016), mainly in the wild-type KRAS group (p= 0.042) and patients over 65 years (p= 0.001). CD44-positive patients had 3.7-fold and 5.3-fold greater risk of liver metastasis and lung metastasis, respectively (p< 0.01), compared with CD44-negative patients. CD166-negative patients had 2.7 greater risk of lymph node involvement (0.03), compared with CD166-positive patients. KRAS mutation increased the risk of liver metastasis by 8 times (p< 0.01), and the risk of lung metastasis by 5 times (p= 0.04) in CD44-positive patients. KRAS mutation increased the risk of lymph node involvement by 8 times in CD166-negative patients (p= 0.0007). An association between CD44 and CD166 expression was demonstrated in this study. Analysis of KRAS mutation combined with immunohistochemical expression of CD44 and CD166 identified subgroups of patients with colon adenocarcinoma at higher risk of lymph node involvement by the tumor and development of liver and lung metastasis.

BRAF, PIK3CA, and HER2 Oncogenic Alterations According to KRAS Mutation Status in Advanced Colorectal Cancers with Distant Metastasis.

BackgroundAnti-EGFR antibody–based treatment is an important therapeutic strategy for advanced colorectal cancer (CRC); despite this, several mutations—including KRAS, BRAF, and PIK3CA mutations, and HER2 amplification—are associated with the mechanisms underlying the development of resistance to anti-EGFR therapy. The aim of our study was to investigate the frequencies and clinical implications of these genetic alterations in advanced CRC.MethodsKRAS, BRAF, and PIK3CA mutations were determined by Cobas real-time polymerase chain reaction (PCR) in 191 advanced CRC patients with distant metastasis. Microsatellite instability (MSI) status was determined by a fragmentation assay and HER2 amplification was assessed by silver in situ hybridization. In addition, KRAS mutations were investigated by the Sanger sequencing method in 97 of 191 CRC cases.ResultsMutations in KRAS, BRAF, and PIK3CA were found in 104 (54.5%), 6 (3.1%), and 25 (13.1%) cases of advanced CRC, respectively. MSI-high status and HER2 amplification were observed in 3 (1.6%) and 16 (8.4%) cases, respectively. PIK3CA mutations were more frequently found in KRAS mutant type (18.3%) than KRAS wild type (6.9%) (P = 0.020). In contrast, HER2 amplifications and BRAF mutations were associated with KRAS wild type with borderline significance (P = 0.052 and 0.094, respectively). In combined analyses with KRAS, BRAF and HER2 status, BRAF mutations or HER2 amplifications were associated with the worst prognosis in the wild type KRAS group (P = 0.004). When comparing the efficacy of detection methods, the results of real time PCR analysis revealed 56 of 97 (57.7%) CRC cases with KRAS mutations, whereas Sanger sequencing revealed 49 cases (50.5%).ConclusionsKRAS mutations were found in 54.5% of advanced CRC patients. Our results support that subgrouping using PIK3CA and BRAF mutation or HER2 amplification status, in addition to KRAS mutation status, is helpful for managing advanced CRC patients.

KRAS as a predictor of poor prognosis and benefit from postoperative FOLFOX chemotherapy in patients with stage II and III colorectal cancer

PurposeThe KRAS gene frequently mutates in colorectal cancer (CRC). Here we investigated the prognostic and predictive role of KRAS mutation in patients with stage II or III CRC. Experimental designA consecutive cohort of patients with stage II or III CRC from a single center database was studied. The association between KRAS status, adjuvant FOLFOX therapy, and 3-year disease-free survival (3-y DFS) was analyzed. ResultsOf our 433 patients, 166 (38.3%) exhibited the KRAS mutation. Among the 190 patients who did not receive adjuvant therapy, those with KRAS mutation tumors had a worse 3-y DFS (hazard ratio [HR], 1.924; 95% confidence interval [CI], 1.078–3.435; P = 0.027). Among patients who received adjuvant chemotherapy, KRAS mutation was not correlated with worse 3-y DFS (HR, 1.083; 95% CI, 0.618–1.899; P = 0.781). Adjuvant chemotherapy improved 3-y DFS only among patients with KRAS mutant tumors (78.0% vs 69.2%) on multivariate analysis adjusted for age, stage, grade, site, vessel invasion, and carcinoembryonic antigen level (HR, 0.454; 95% CI, 0.229–0.901; P = 0.024). In contrast, there was no benefit of adjuvant chemotherapy in the KRAS wild-type group (84.3% vs 82.0%). ConclusionsKRAS mutation indicates poor prognosis. FOLFOX adjuvant chemotherapy benefits patients with stage II or III colorectal cancer with KRAS mutant tumors and is worth further investigation.

PCR-based assays versus direct sequencing for evaluating the effect of KRAS status on anti-EGFR treatment response in colorectal cancer patients: a systematic review and meta-analysis.

BackgroundThe survival rate of colorectal cancer (CRC) patients carrying wild-type KRAS is significantly increased by combining anti-EGFR monoclonal antibody (mAb) with standard chemotherapy. However, conflicting data exist in both the wild-type KRAS and mutant KRAS groups, which strongly challenge CRC anti-EGFR treatment. Here we conducted a meta-analysis in an effort to provide more reliable information regarding anti-EGFR treatment in CRC patients.MethodsWe searched full reports of randomized clinical trials using Medline, the American Society of Clinical Oncology (ASCO), and the European Society for Medical Oncology (ESMO). Two investigators independently screened the published literature according to our inclusive and exclusive criteria and the relative data were extracted. We used Review Manager 5.2 software to analyze the data.ResultsThe addition of anti-EGFR mAb to standard chemotherapy significantly improved both progression-free survival (PFS) and median overall survival (mOS) in the wild-type KRAS group; hazard ratios (HRs) for PFS and mOS were 0.70 [95% confidence interval (CI), 0.58–0.84] and 0.83 [95% CI, 0.75–0.91], respectively. In sub-analyses of the wild-type KRAS group, when PCR-based assays are employed, PFS and mOS notably increase: the HRs were 0.74 [95% CI, 0.62–0.88] and 0.87 [95% CI, 0.78–0.96], respectively. In sub-analyses of the mutant KRAS group, neither PCR-based assays nor direct sequencing enhance PFS or mOS.ConclusionOur data suggest that PCR-based assays with high sensitivity and specificity allow accurate identification of patients with wild-type KRAS and thus increase PFS and mOS. Furthermore, such assays liberate patients with mutant KRAS from unnecessary drug side effects, and provide them an opportunity to receive appropriate treatment. Thus, establishing a precise standard reference test will substantially optimize CRC-targeted therapies.

CP-053 Effectiveness assessment of first-line treatment in metastatic colorectal cancer according to mutational KRAS status

BackgroundKRAS gene mutations are associated with a worse metastatic colorectal cancer (mCRC) prognosis.PurposeTo assess the effectiveness of the first-line treatment of mCRC according to KRAS mutational status.Materials and methodsRetrospective and...

Correlation of KRAS mutational state with the expression of the hedgehog pathway in patients with pancreatic ductal adenocarcinoma.

227 Background: Pancreatic ductal adenocarcinoma (PDAC) is commonly associated with mutations in the KRAS gene. However, how KRAS mutations promote pancreatic carcinogenesis has not been fully established. Here we examine the association between KRAS mutational state and the expression of different tumor markers in PDAC samples. Methods: Immunohistochemical analysis was performed on PDAC specimens to identify the levels of expression of 28 surface and nuclear proteins: BRCA1, BRCA2, NOTCH1, SPARC, SHH, DHH, IHH, SMO, PTCH1, PTCH2, ALCAM, OCT3.4, PROM1, CD44, CD24, LGR5, BMP4, KDR, FLT1, PDGFRB, VEGFA, VEGFB, PGF, CDKN2A, SMAD4, MET, HGF, MUC6. All samples were also tested for identification of KRAS isoforms (wild type (WT) vs mutated type (MT)) expression by means of RT-PCR. Levels of mRNA expression were matched with a common standard tissue marker. Expression levels of PDAC markers were compared between MT and WT KRAS groups. Differences between groups were tested using Mann-Whitney U test for unpaired samples. Exploratory univariate logistic regression was also performed to evaluate possible correlations between increasing levels of each marker and KRAS mutational state. Results: 110 samples were collected. Of them, data on KRAS were provided for 86 samples; 40 and 46 samples expressed the WT and MT KRAS isofo rms, respectively. Preliminary analysis showed that the expression of SHH and IHH resulted significantly higher in KRAS MT samples (U=1097 p= 0.013 and U=1072 p= 0.028 respectively), whereas higher levels of SMAD4 (U=634, p= 0.012) and HGF (U= 655, p= 0.03) were expressed in the KRAS WT group. A weak difference between groups was found for the MUC6 pathway (U= 666, p= 0.056). No differences of VEGFA, VEGFB and VEGFRB expression were found between MT and WT groups. At univariate logistic regression we found that increased levels of SHH correlated with the expression of KRAS MT phenotype (OR 57.5, p= 0.011), while IHH showed only a weaker significance level (OR 13.1, p= 0.069). Conclusions: These results indicate that oncogenic KRAS is directly associated with SHH expression in PDAC tissues. They also mark Hedgehog pathway components as relevant therapeutic targets for KRAS-mutant patients.

Clinical benefits of bevacizumab in metastatic colorectal cancer depending on KRAS status.

636 Background: KRAS status is the therapeutic marker of anti-EGFR drug, and may be the prognostic marker of metastatic colorectal cancer (mCRC). However, there is no consensus whether bevacizumab (anti-VEGF drug) benefits patients with mutated KRAS in mCRC. We investigated the clinical benefits of bevacizumab treatment in mCRC depending on KRAS status, retrospectively. Methods: We investigated 49 patients who received chemotherapies with bevacizumab as first-line treatment for mCRC from May 2008 through June 2013. We evaluated response rate (RR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), tumor reduction rate and the adverse events (CTCAE v4.0 - JCOG) depending on KRAS status. Results: The median age of the patients was 66 years (range; 36 - 80). Forty-five patients received oxaliplatin-based chemotherapies with bevacizumab and four patients received irinotecan-based chemotherapies with bevacizumab. KRAS status of 30 patients was wild type and that of 19 patients was mutation type. There was no difference in patient characteristics between KRAS wild type (WT) and mutation type (MT). In all 49 patients, RR was 62.5%. DCR was 91.7%. The median PFS was 10.9 months. In RR, patients with KRAS wild type tumors had better outcome than patients with mutant type tumors (WT : MT, 69.0% : 52.6%, no statistically difference). A similar tendency was seen in DCR (WT : MT, 96.6% : 84.2%, no statistically difference). The average reduction rate in KRAS WT was 42.7% and in KRAS MT was 32.3% (p = 0.309). In the KRAS wild patients, the median PFS was longer than that in the KRAS mutant patients (WT : MT, 11.8 : 8.9 months, Log Rank p = 0.583), but there is no statistically difference between two groups. In median OS, there was no difference between two groups (WT : MT, 21.0 : 20.8 months, Log Rank p = 0.393). The incidence of severe adverse events was not statistically different between KRAS WT group and MT group. Conclusions: Regardless of KRAS status, bevacizumab provides clinical benefits for patients with mCRC.

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.