Clinical usefulness of KRAS, BRAF, and PIK3CA mutations as predictive markers of cetuximab efficacy in irinotecan- and oxaliplatin-refractory Japanese patients with metastatic colorectal cancer

RAS mutation status in combination with the JSHBPS nomogram may be useful for preoperative identification of colorectal liver metastases with high risk of recurrence and mortality after hepatectomy

PURPOSE

To investigate the prognostic impact of RAS mutations on the Japanese Society of Hepatobiliary and Pancreatic Surgeons (JSHBPS) nomogram score in patients with colorectal cancer liver metastasis (CRLM) following hepatectomy.

METHODS

We included 218 consecutive patients undergoing hepatectomy for CRLM between 2004 and 2020. The JSHBPS nomogram score was calculated using six preoperative clinical factors. The score ranged from 0 to 25, and higher scores indicated greater tumor burden. Associations of RAS mutations with disease-free survival (DFS) and overall survival (OS) by the JSHBPS nomogram score were examined. Multivariable Cox proportional hazard regression models were used to estimate adjusted hazard ratios (HRs) and confidence intervals (CIs).

RESULTS

RAS mutations were detected in 72 (33%) of the 218 patients. Multivariate analyses revealed that RAS mutations were independently associated with poor DFS (HR, 1.93; 95% CI: 1.20-3.10; p = .007) and OS (HR, 2.65; 95% CI: 1.59-4.71; p = .001) compared with wild-type RAS with JSHBPS nomogram scores ≤ 10. However, in patients with scores ≥ 11, the association of RAS mutations with DFS or OS was not statistically significant (p > .08).

CONCLUSION

RAS mutation status in combination with the JSHBPS nomogram may be useful for preoperatively identifying CRLM with high risk of recurrence and mortality after hepatectomy.

Dynamics of the prognostic nutritional index in preoperative chemotherapy in patients with colorectal liver metastases

BACKGROUND

Identifying the prognostic indicators that reflect the efficacy of preoperative chemotherapy is necessary. In this study, we investigated the prognostic indicators targeting the systemic inflammatory response for the administration of preoperative chemotherapy in patients with colorectal liver metastases.

METHODS

Data for 192 patients were retrospectively analyzed. The relationship between overall survival and clinicopathological variables, including biomarkers such as the prognostic nutritional index, was investigated in patients who underwent upfront surgery or preoperative chemotherapy.

RESULTS

In the upfront surgery group, extrahepatic lesion (p=0.01) and low prognostic nutritional index (p < 0.01) were significant prognostic indicators, whereas a decrease in the prognostic nutritional index (p=0.01) during preoperative chemotherapy were independent poor prognostic factors in the preoperative chemotherapy group. In particular, a decrease in the prognostic nutritional index was a significant prognostic marker in patients aged <75 years (p=0.04). In patients with a low prognostic nutritional index aged <75 years, preoperative chemotherapy significantly prolonged overall survival (p=0.02).

CONCLUSION

A decrease in the prognostic nutritional index during preoperative chemotherapy predicted overall survival of patients with colorectal liver metastases after hepatic resection, and preoperative chemotherapy may be effective for patients aged <75 years with a low prognostic nutritional index.

Prognostic and Predictive Value of PIK3CA Mutations in Metastatic Colorectal Cancer

BACKGROUND

Comprehensive genomic profiling is used to guide the management of metastatic colorectal cancer (mCRC); however, the role of PIK3CA mutations, present in up to 20% of mCRCs, is unclear.

OBJECTIVE

This study aimed to evaluate the association of PIK3CA mutations with other common mutations in mCRC and determine the prognostic and predictive value of PIK3CA mutations.

PATIENTS AND METHODS

A retrospective chart review was performed on patients in the Moffitt Clinical Genomic Database with mCRC. A meta-analysis was performed to further evaluate the predictive value of PIK3CA mutations to the response to anti-epidermal growth factor receptor (EGFR) therapy.

RESULTS

Among 639 patients, PIK3CA was positively correlated with KRAS mutation (r = 0.11, p = 0.006) and negatively correlated with TP53 mutation (r = - 0.18, p ≤ 0.001) and ERBB2 amplification (r = - 0.08, p = 0.046). The median overall survival (OS) of patients with PIK3CA-mutant mCRC (n = 49) was 35.5 (95% confidence interval [CI] 18.7-48.1) months vs. 55.3 (95% CI 47.5-65.6) months for PIK3CA wild-type mCRC (n = 286) [p = 0.003]. This OS difference remained significant with exon 9 and exon 20 subset analyses. There was no significant difference in response rate between patients with PIK3CA wild-type (n = 97) versus mutant (n = 9) mCRC who received anti-EGFR therapy (43% vs. 56%, p = 0.61) and no significant difference in median progression-free survival (PFS) of 10.3 versus 7.2 months (p = 0.60). However, our meta-analysis of 12 studies, including ours, using a common effect model identified that PIK3CA mutations are associated with reduced response to anti-EGFR therapy, with a relative risk of 0.56 (95% CI 0.38-0.82).

CONCLUSION

Our study identified PIK3CA mutations as a poor prognostic factor, and our meta-analysis identified PIK3CA mutations as predictive of decreased response to anti-EGFR therapy in patients with mCRC.

KRAS and BRAF mutations in Iranian colorectal cancer patients: A systematic review and meta-analysis

Background:

Mutations in the EGFR signaling pathway play an important role in the development of colorectal cancer (CRC). Mutations in these genes, like KRAS and BRAF, affect the treatment strategies and associated with poor prognosis and relative resistance to anti-EGFR therapies. Our aim was to conduct a systematic and meta-analysis on all studies that have been conducted on the prevalence of these gene mutations in Iranian CRC patients.

Methods:

Four science citation index databases (MEDLINE, EMBASE, Web of Science and Cochrane library) and local databases were searched up to March 2018 with related keywords. Two reviewers independently screened and extracted the data. Quality of all included studies was assessed using an adapted checklist from STROBE. A random-effect model was used to calculate the total prevalence of KRAS and BRAF mutations in CRC subjects by the event rate (ER). Meta-regression was utilized to explore heterogeneity causes.

Results:

In total, from 573 records, 23 eligible studies (2662 patients) were included for data extraction and analysis. In 18 of 23 included studies, the prevalence of KRAS mutations was 33.9% (95% CI=30.1-37.9) with I2=65.17 (p<0.001). The occurrence of KRAS mutations in codon 12 and 13 was 76.9% (95% CI = 70.4-82.3%) with I2=84.88 (p<0.001) and 23.5% (95% CI=17.9-30.3) with I2=85.85 (p<0.001), respectively. In 9 of 23 studies, the BRAF mutation rate was 3.2% (95% CI=0.003-13.6) with I2=88.61 (p<0.001).

Conclusion:

The prevalence of these mutations in CRC patients shows a significant difference in the different regions of Iran, which is probably due to environmental and racial factors.

Pan-Asian adapted ESMO consensus guidelines for the management of patients with metastatic colorectal cancer: a JSMO-ESMO initiative endorsed by CSCO, KACO, MOS, SSO and TOS

The most recent version of the European Society for Medical Oncology (ESMO) consensus guidelines for the treatment of patients with metastatic colorectal cancer (mCRC) was published in 2016, identifying both a more strategic approach to the administration of the available systemic therapy choices, and a greater emphasis on the use of ablative techniques, including surgery. At the 2016 ESMO Asia Meeting, in December 2016, it was decided by both ESMO and the Japanese Society of Medical Oncology (JSMO) to convene a special guidelines meeting, endorsed by both ESMO and JSMO, immediately after the JSMO 2017 Annual Meeting. The aim was to adapt the ESMO consensus guidelines to take into account the ethnic differences relating to the toxicity as well as other aspects of certain systemic treatments in patients of Asian ethnicity. These guidelines represent the consensus opinions reached by experts in the treatment of patients with mCRC identified by the Presidents of the oncological societies of Japan (JSMO), China (Chinese Society of Clinical Oncology), Korea (Korean Association for Clinical Oncology), Malaysia (Malaysian Oncological Society), Singapore (Singapore Society of Oncology) and Taiwan (Taiwan Oncology Society). The voting was based on scientific evidence and was independent of both the current treatment practices and the drug availability and reimbursement situations in the individual participating Asian countries.

Impact of CDX2 expression status on the survival of patients after curative resection for colorectal cancer liver metastasis

BACKGROUND

The prognostic biomarker for patients undergoing curative liver metastasectomy for colorectal cancer (CRC) is lacking. The purpose was to investigate the prognostic role of a lack of CDX2 expression, which has been proposed as a potential biomarker for high-risk relapse in early-stage CRC, in patients undergoing curative liver metastasectomy.

METHODS

A total of 396 consecutive patients with CRC liver metastasis who underwent potentially curative liver metastasectomy at a single center in Japan between 2005 and 2015 were included. For the immunohistochemical analysis of nuclear CDX2 expression, we adopted the tissue microarray approach using the resected metastatic liver CRCs. Patient subgroups were compared with respect to disease-free survival (DFS) and overall survival (OS) by applying the Kaplan-Meier curve, log-rank tests, and multivariate analyses based on the Cox proportional hazards method. OS is defined as the period from the date of curative liver resection for metastatic CRC until death. DFS is defined as the length of time from curative liver resection to either the first recurrence or death. In patients without recurrence, the latest imaging inspection date was used as the censored date.

RESULTS

Thirty-six of the 396 CRCs (9.1%) reduced CDX2 expression. The reduced expression of CDX2 was associated with poor differentiation (P = 0.02). DFS in days was lower in the patients with CDX2-low CRC than in the patients with CDX2-high CRC (median DFS: 245 days versus 420 days; hazard ratio for disease recurrence: 1.64; 95% confidence interval: 1.08-2.38; P = 0.02). OS in days was lower in the patients with CDX2-low CRC than in the patients with CDX2-high CRC (median OS: 1024 days versus 3145 days; hazard ratio: 2.41; 95% confidence interval: 1.52-3.85; P <  0.001). In patients with CDX2-low CRC, both DFS and OS were similar between the with and without pre- or post-operative chemotherapy groups (median DFS: 243 versus 247 days; P = 0.73, median OS: 1016 versus 1363 days; P = 0.69).

CONCLUSIONS

Reduced expression of CDX2 indicates poor DFS and OS, however, it might not represent chemosensitivity in patients undergoing curative liver metastasectomy. (339/350).

Mutations of KRAS/NRAS/BRAF predict cetuximab resistance in metastatic colorectal cancer patients

Approximately 45% of metastatic colorectal cancer (mCRC) patients with wild-type KRAS exon 2 are resistant to cetuximab treatment. We set out to identify additional genetic markers that might predict the response to cetuximab treatment. Fifty-three wild-type KRAS exon 2 mCRC patients were treated with cetuximab/irinotecan-based chemotherapy as a first- or third-line therapy. The mutational statuses of 10 EGFR pathway genes were analyzed in primary tumors using next-generation sequencing. BRAF, PIK3CA, KRAS (exons 3 and 4), NRAS, PTEN, and AKT1 mutations were detected in 6, 6, 5, 4, 1, and 1 patient, respectively. Four of the BRAF mutations were non-V600 variants. Four tumors harbored multiple co-existing (complex) mutations. All patients with BRAF mutations or complex mutation patterns were cetuximab non-responders. All patients but one harboring KRAS, NRAS, or BRAF mutations were non-responders. Mutations in any one of these three genes were associated with a poor response rate (7.1%) and reduced survival (PFS = 8.0 months) compared to wild-type patients (74.4% and 11.6 months). Our data suggest that KRAS, NRAS, and BRAF mutations predict response to cetuximab treatment in mCRC patients.

Germline polymorphisms as biomarkers of tumor response in colorectal cancer patients treated with anti-EGFR monoclonal antibodies: a systematic review and meta-analysis

Studies of germline polymorphisms as predictors of tumor response to anti-epidermal growth factor receptor (EGFR) monoclonal antibody agents in metastatic colorectal cancer have reported inconsistent results. We performed a systematic review of studies from 1990 to September 2015, followed by random-effects meta-analyses for polymorphisms examined in at least three studies. Of 87 studies, 40 passed the criteria for systematic review and 23 for meta-analysis. The polymorphisms suitable for meta-analysis were CCND1 (rs17852153), COX2 (rs20417), EGF (rs4444903), EGFR (rs712829, rs11543848, 3'UTR CA repeat), FCGR2A (rs1801274), FCGR3A (rs396991), IL8 (rs4073), KRAS (rs61764370) and VEGFA (rs3025039). Meta-analysis yielded nominal significance (at α=0.05) for rs4444903 and rs11543848, but showed no significant results after multiple testing correction; this was unchanged by sensitivity analyses to address subgroups, funnel-plot asymmetries, and study quality. This highlights a tendency for lack of replication in the face of initial positive results, and possibly the unsuitability of relying on tumor response as a surrogate marker in this setting.

KRAS/BRAF基因与结肠癌糖代谢研究现状

正电子发射断层成像术(positron emission tomography, PET)/计算机断层扫描(computed tomography, CT)显像可用于结肠癌的诊断、监测疗效和预后评估. ¹⁸F标记葡萄糖(2-fluorine-18-fluoro-2-deeoxy-D-glucose, ¹⁸F-FDG)是PET/CT常用显像剂, 可以反映结肠癌活体组织葡萄糖代谢. KRAS/BRAF基因检测常用于结肠癌靶向治疗方案的选择及评估其治疗效果. 文献报道¹⁸F-FDG-PET/CT显像可预测结肠癌KRAS/BRAF基因状态, 能以无创的方式预测结肠癌抗表皮生长因子受体靶向治疗效果. 目前国内有关KRAS/BRAF基因与结肠癌糖代谢的研究相对较少, 本文结合近期的相关文献进行概述.

Predictive model for high-frequency microsatellite instability in colorectal cancer patients over 50 years of age

Microsatellite instability (MSI) is an important biomarker for screening for Lynch syndrome, and also of response to immune checkpoint inhibitors. The aim of this study is to create a predictive model to determine which elderly patients with colorectal cancer (CRC) should undergo MSI and/or immunohistochemistry testing on the basis of clinicopathological data. We analyzed a test cohort of CRC patients aged ≥50 years (n = 2219) by multivariate logistic regression analyses to identify predictors of high‐frequency MSI (MSI‐H). The created prediction model was validated in an external cohort (n = 992). The frequency of MSI‐H was 5.5% among CRC patients aged ≥ 50 years. The following five predictors of MSI‐H were identified in the test cohort: female (1 point), mucinous component (2 points), tumor size ≥ 60 mm (2 points), location in proximal colon (3 points), and BRAF mutation (6 points). The area under curve (AUC) in the receiver‐operating characteristic (ROC) analysis of this prediction model was 0.832 (95% confidence interval: 0.790–0.874). The sensitivity and specificity were 74.4% and 77.7%, respectively, for a cut‐off score of 4 points. The receiver‐operating characteristic curve of the validation cohort also showed an AUC of 0.856 (95% CI: 0.806–0.905). This prediction model is useful to select elderly CRC patients who should undergo MSI testing, and who may benefit from treatment with 5‐FU‐based adjuvant chemotherapy and cancer immunotherapy.

Molecular spectrum of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC somatic gene mutations in Arab patients with colorectal cancer: determination of frequency and distribution pattern

BACKGROUND

The frequency rates of mutations such as KRAS, NRAS, BRAF, and PIK3CA in colorectal cancer (CRC) differ among populations. The aim of this study was to assess mutation frequencies in the Arab population and determine their correlations with certain clinicopathological features.

METHODS

Arab patients from the Arab Gulf region and a population of age- and sex-matched Western patients with CRC whose tumors were evaluated with next-generation sequencing (NGS) were identified and retrospectively reviewed. The mutation rates of KRAS, NRAS, BRAF, PIK3CA, TP53, and APC were recorded, along with clinicopathological features. Other somatic mutation and their rates were also identified. Fisher's exact test was used to determine the association between mutation status and clinical features.

RESULTS

A total of 198 cases were identified; 99 Arab patients and 99 Western patients. Fifty-two point seven percent of Arab patients had stage IV disease at initial presentation, 74.2% had left-sided tumors. Eighty-nine point two percent had tubular adenocarcinoma and 10.8% had mucinous adenocarcinoma. The prevalence rates of KRAS, NRAS, BRAF, PIK3CA, TP53, APC, SMAD, FBXW7 mutations in Arab population were 44.4%, 4%, 4%, 13.1%, 52.5%, 27.3%, 2% and 3% respectively. Compared to 48.4%, 4%, 4%, 12.1%, 47.5%, 24.2%, 11.1% and 0% respectively in matched Western population. Associations between these mutations and patient clinicopathological features were not statistically significant.

CONCLUSIONS

This is the first study to report comprehensive hotspot mutations using NGS in Arab patients with CRC. The frequency of KRAS, NRAS, BRAF, TP53, APC and PIK3CA mutations were similar to reported frequencies in Western population except SMAD4 that had a lower frequency and higher frequency of FBXW7 mutation.

CpG island methylator phenotype is associated with the efficacy of sequential oxaliplatin- and irinotecan-based chemotherapy and EGFR-related gene mutation in Japanese patients with metastatic colorectal cancer

BACKGROUND

The CpG island methylator phenotype (CIMP) with multiple promoter methylated loci has been observed in a subset of human colorectal cancer (CRC) cases. CIMP status, which is closely associated with specific clinicopathological and molecular characteristics, is considered a potential predictive biomarker for efficacy of cancer treatment. However, the relationship between the effect of standard chemotherapy, including cytotoxic drugs and anti-epidermal growth factor receptor (EGFR) antibodies, and CIMP status has not been elucidated.

METHODS

In 125 metastatic colorectal cancer (mCRC) patients, we investigated how clinical outcome of chemotherapy was related to CIMP status as detected by methylation-specific PCR (MSP) and to genetic status in five EGFR-related genes (KRAS, BRAF, PIK3CA, NRAS, and AKT1) as detected by direct sequencing.

RESULTS

CIMP-positive status was significantly associated with proximal tumor location and peritoneum metastasis (all P values <0.05). The progression-free survival of patients with CIMP-positive tumors receiving sequential therapy with FOLFOX as the first-line treatment followed by irinotecan-based therapy as the second-line treatment (median = 6.6 months) was inferior to that of such patients receiving the reverse sequence (median = 15.2 months; P = 0.043). Furthermore, CIMP-positive tumors showed higher mutation frequencies for the five EGFR-related genes (74.1 %) than the CIMP-negative tumors did (50.0 %). Among the KRAS wild-type tumors, CIMP-positive tumors were associated with a worse clinical outcome than CIMP-negative tumors following anti-EGFR antibody therapy.

CONCLUSION

Sequential FOLFOX followed by an irinotecan-based regimen is unfavorable in patients with CIMP-positive tumors. High frequencies of mutation in EGFR-related genes in CIMP-positive tumors may cause the lower response to anti-EGFR antibody therapy seen in patients with wild-type KRAS and CIMP-positive tumors.

Molecular spectrum of KRAS, NRAS, BRAF and PIK3CA mutations in Chinese colorectal cancer patients: analysis of 1,110 cases

Mutations in genes such as KRAS, NRAS, BRAF and PIK3CA have become an important part of colorectal carcinoma evaluation. The aim of this study was to screen for mutations in these genes in Chinese patients with colorectal cancer (CRC) and to explore their correlations with certain clinicopathological parameters. We tested mutations in the KRAS (exons 2, 3 and 4), NRAS (exons 2, 3 and 4), PIK3CA (exon 20) and BRAF (exon 15) genes using reverse transcriptase-polymerase chain reaction (RT-PCR) and Sanger sequencing in a large cohort of 1,110 Chinese CRC patients who underwent surgical resection at one of three major teaching hospitals located in different regions of China. The prevalence rates of KRAS, NRAS, BRAF and PIK3CA mutations were 45.4%, 3.9%, 3.1% and 3.5%, respectively. Mutant KRAS was associated with the mucinous subtype and greater differentiation, while mutant BRAF was associated with right-sided tumors and poorer differentiation. Our results revealed differences in the genetic profiles of KRAS, NRAS, PIK3CA and BRAF at mutation hotspots between Chinese CRC patients and those of Western countries, while some of these gene features were shared among patients from other Asian countries.

Mutation of the PIK3CA gene as a prognostic factor in patients with colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide, with ~700,000 mortalities occurring due to CRC in 2012. The treatment options are effective in a small percentage of patients, and it is important to identify specific biomarkers in order to determine patients for whom the available therapies will be beneficial. It has been hypothesised that the PIK3CA gene mutation may affect the response to therapy of patients with metastatic CRC. In the present study, primary tumour specimens were collected from 156 patients with CRC who were treated in the Military Institute of Medicine in Warsaw (Warsaw, Poland). Codons 12 and 13 of exon 1 of KRAS, exons 11 and 15 of BRAF and exons 9 and 20 of PIK3CA were analysed for mutation using direct sequencing. The prognostic value of each mutation and the clinical and pathological variables of these tumours were estimated. The results revealed that PIK3CA mutations were present in 15 patients (9.6%), of whom seven (46.7%) possessed mutations in codon 9 and eight (53.3%) possessed mutations in codon 20. Mutation in the PIK3CA gene was detected in six patients with KRAS gene mutations, which accounted for 40% of PIK3CA-mutated tumours, and in one patient with BRAF mutations, which accounted for 6.6% of PIK3CA-mutated tumours. No significant differences were identified between the overall survival (OS) rates of patients with PIK3CA mutations (median OS, 56.7 months) and those with wild-type PIK3CA genes (median OS, 47.6 months) (P=0.1270). Univariate analysis identified that the following prognostic factors affected the OS rate in the current patient cohort: Gender, female patients survived for 57.5 months compared with 39.3 months for male patients (P=0.0111); and lymph node involvement grade, as survival of patients without lymph node metastases was 61.4 months compared with 45.4 months in patients presenting with metastases (P=0.0122). The findings of the present analysis indicate that PIK3CA mutation status is not a prognostic factor in CRC patients. In addition, no statistically significant association exists between tumours with PIK3CA mutations and clinical or pathological factors.

Extended RAS testing in metastatic colorectal cancer-Refining the predictive molecular biomarkers

Mutations of exon 2 of Kirsten rat sarcoma viral oncogene homologue (KRAS) (exon 2 codons 12/13) lead to constitutive activation of the EGFR (epidermal growth factor receptor) mediated signal transduction pathway and been shown to be a negative predictive biomarker for EGFR-directed monoclonal antibodies among patients with colorectal cancer (CRC). As selection of patients is very important for administration of anti-EGFR therapy, this lone biomarker has proved to be insufficient for selecting the appropriate patients as more patients lacking exon 2 KRAS mutation were resistant to anti-EGFR therapy. The results of various randomized clinical trials have confirmed the presence of other RAS mutation including additional RAS mutations (KRAS exons 3/4 and NRAS exon 1/2/3/4). Extended RAS analysis should be considered before initiating anti-EGFR therapy to patients of metastatic CRC. This can help in proper selection of patients leading to tailored individualistic treatment, decreasing cost of treatment and the adverse effects related to use of monoclonal antibody therapy. The new evidence is supporting the need to make 'Extended RAS' analysis essential before start of treatment with anti-EGFR monoclonal antibody therapy. Prior to this the Extended RAS testing should be standardized.

Gene-expression profiles correlate with the efficacy of anti-EGFR therapy and chemotherapy for colorectal cancer

BACKGROUND

Comprehensive gene-expression analysis is very useful for classifying specific cancers into subgroups on the basis of their biological characteristics; it is used both prognostically and predictively. The purpose of this study was to classify unresectable advanced or recurrent colorectal cancer (CRC) by gene-expression profiling of formalin-fixed paraffin-embedded tissues and to correlate CRC subgroups with clinicopathological and molecular features and clinical outcomes.

METHODS

One hundred patients with advanced or recurrent CRC were enrolled. RNA extracted from FFPE tissues was subjected to gene-expression microarray analysis.

RESULTS

The patients were stratified into four subgroups (subtypes A1, A2, B1, and B2) by unsupervised hierarchical clustering. By use of principle-components analysis (PCA), the patients were divided into subtypes A and B on the basis of component 1 and into subtypes 1 and 2 on the basis of component 2. Subtype A was significantly enriched among patients without the KRAS mutation and with an earlier clinical stage at diagnosis. With regard to anti-EGFR therapy, progression-free survival (PFS) was better for patients in subtype A without the KRAS mutation than for those with the KRAS mutation (P = 0.047). PFS for patients without the KRAS mutation in subtype B was comparable with that for patients with the KRAS mutation (P = 0.55). Similar results were observed in a validation set.

CONCLUSION

We found that gene-expression profiles enabled stratification of CRC patients into four subgroups. The efficacy of anti-EGFR therapy was correlated with component 1 from PCA. This comprehensive study may explain the heterogeneity of unresectable advanced or recurrent CRC and could be useful for identifying novel biomarkers for CRC treatment.

Elucidating the prognostic significance of KRAS, NRAS, BRAF and PIK3CA mutations in Chinese patients with metastatic colorectal cancer

AIM

The prognostic significance of KRAS, NRAS, PIK3CA and BRAF mutations was evaluated in Chinese patients with metastatic colorectal cancer (CRC).

METHOD

Tumor samples from 183 patients were retrospectively tested for KRAS, NRAS, PIK3CA and BRAF mutations. Multivariate analysis was performed to determine the relationship between mutational status, drug response and survival.

RESULT

Over 70% of patients received two or more lines of chemotherapy, 50% had cetuximab and 18% had bevacizumab. The prevalence of KRAS, NRAS, BRAF and PIK3CA mutations was 45, 3.2, 5 and 20%, respectively. For the entire cohort, the median overall survival was 24 months (95% confidence interval [CI] = 20.4-26.4 months). Of the genes tested, only KRAS mutation was an independent prognostic factor with a multivariate hazard ratio of 1.5 (95% CI = 1.05-2.16, P = 0.03). In the subgroup of patients who received cetuximab-based therapy in the first-line setting, KRAS mutation was associated with a lack of response to chemotherapy (28% vs 66%, chi-square, P = 0.01). Patients with KRAS mutant tumors (or KRAS wild-type tumors that harbored BRAF and/or PIK3CA mutations) tended to have lower response rates to chemotherapy and/or cetuximab (P = not significant). The number of NRAS mutant cases was too small to allow any statistical analysis.

CONCLUSION

The prevalence of KRAS, NRAS, BRAF and PIK3CA mutations in this cohort is consistent with reports from non-Asian populations, and KRAS mutation has both prognostic and predictive significance in Chinese patients with metastatic CRC.

Clinicopathologic Significance of BRAF Mutation and Extracellular Signal Regulated Kinase 1/2 Expression in Patients With a Colorectal Adenocarcinoma

Purpose

BRAF mutation and expression of extracellular signal regulated kinase (ERK) are linked with colorectal carcinogenesis through the serrated pathway. BRAF and ERK1/2 play important roles in the activation of mitogen-activated protein (MAP) kinase signaling pathways. The present study investigated the clinicopathologic outcomes of BRAF mutation and ERK1/2 expression in patients with colorectal cancer (CRC) and the possibility of using them as prognostic indicators.

Methods

Dual-priming oligonucleotide-based multiplex polymerase chain reaction for BRAF^V600E mutation and immunohistochemical analysis of ERK1/2 were performed using 65 formalin-fixed, paraffin-embedded samples from patients with CRC. We analyzed the dependences of the clinicopathologic features on BRAF mutation and ERK1/2 expression.

Results

Out of 65 samples from CRC patients, BRAF mutation was detected in 3 (4.6%). The 3 patients with BRAF mutation presented with T3 CRC with lymph node metastasis (stage III) showing moderately or poorly differentiated histology. ERK1 and ERK2 were positively detected in 73.8% and 15.4% of the patients with CRC, respectively. ERK1 expression was significantly correlated with lymph node metastasis (P = 0.049). ERK2 expression was significantly correlated with tumor emboli (P < 0.05), tumor invasion (P = 0.035), lymph node metastasis (P = 0.017), and stage (P = 0.02).

Conclusion

BRAF mutation and ERK1/2 expression may be associated with advanced or more aggressive CRC. These molecular markers might play prognostic roles in CRC developed through the serrated pathway.

Beyond KRAS status and response to anti-EGFR therapy in metastatic colorectal cancer

In patients with metastatic colorectal cancer, overall survival has improved over the last decade mainly due to the use of effective targeted therapies such as anti-EGFR. However, survival improvement is linked to proper selection of patients expected to benefit from these treatments. KRAS codons 12 and 13 mutation status was the first validated molecular biomarker for anti-EGFR antibodies. Today, rare KRAS alterations and NRAS mutations were implemented, defining the 'RAS' status as the new validated marker of response to anti-EGFR antibodies. Moreover, other biomarkers are under investigation to screen for other targets and help with patients selection. Here, we reviewed these promising biomarkers: mutations in the RAS-MAPK and PI3K-AKT pathways genes, MET activation, HER/ErbB receptors activation (EGFR, HER2 and HER3), EGFR ligands, antibody-dependent cell-mediated cytotoxicity) and miRNAs. Further data are needed to define their impact for the treatment of patients with metastatic colorectal cancer.

Resistance to anti-EGFR therapy in colorectal cancer: from heterogeneity to convergent evolution

The EGFR-targeted antibodies cetuximab and panitumumab are used to treat metastatic colorectal cancers. Mutations in KRAS, NRAS, and BRAF and amplification of ERBB2 and MET drive primary (de novo) resistance to anti-EGFR treatment. Recently, the emergence of alterations in the same genes was detected in patients who responded to EGFR blockade and then relapsed. These results illuminate a striking overlap between genes that, when mutated, drive primary and secondary resistance to anti-EGFR antibodies. Remarkably, although the mechanisms of resistance are genetically heterogeneous, they biochemically converge on key signaling pathways. This knowledge is being translated in the rational design of additional lines of therapy.

SIGNIFICANCE

Anti-EGFR-targeted therapies are used for the treatment of metastatic colorectal cancer. Molecular heterogeneity impairs their efficacy by fuelling de novo and acquired resistance. In this review, we highlight how genetically distinct resistance mechanisms biochemically converge on a limited number of signaling pathways that can be therapeutically intercepted.

Molecular spectrum of KRAS, BRAF, and PIK3CA gene mutation: determination of frequency, distribution pattern in Indian colorectal carcinoma

Molecular evaluation of KRAS, BRAF, and PIK3CA mutation has become an important part in colorectal carcinoma evaluation, and their alterations may determine the therapeutic response to anti-EGFR therapy. The current study demonstrates the evaluation of KRAS, BRAF, and PIK3CA mutation using direct sequencing in 204 samples. The frequency of KRAS, BRAF, and PIK3CA mutations was 23.5, 9.8, and 5.9 %, respectively. Five different substitution mutations at KRAS codon 12 (G12S, G12D, G12A, G12V, and G12C) and one substitution type at codon 13 (G13D) were observed. KRAS mutations were significantly higher in patients who were >50 years, and were associated with moderate/poorly differentiated tumors and adenocarcinomas. All mutations in BRAF gene were of V600E type, which were frequent in patients who were ≤ 50 years. Unlike KRAS mutations, BRAF mutations were more frequent in well-differentiated tumors and right-sided tumors. PIK3CA-E545K was the most recurrent mutation while other mutations detected were T544I, Q546R, H1047R, G1049S, and D1056N. No significant association of PIK3CA mutation with age, tumor differentiation, location, and other parameters was noted. No concomitant mutation of KRAS and BRAF mutations was observed, while, interestingly, five cases showed concurrent mutation of KRAS and PIK3CA mutations. In conclusion, to our knowledge, this is the first study to evaluate the PIK3CA mutation in Indian CRC patients. The frequency of KRAS, BRAF, and PIK3CA was similar to worldwide reports. Furthermore, identification of molecular markers has unique strengths, and can provide insights into the pathogenic process and help optimize personalized prevention and therapy.

The predictive value of KRAS, NRAS, BRAF, PIK3CA and PTEN for anti-EGFR treatment in metastatic colorectal cancer: A systematic review and meta-analysis

BACKGROUND

In metastatic colorectal cancer, mutation testing for KRAS exon 2 is widely implemented to select patients with wild-type tumors for treatment with the monocloncal anti-EGFR antibodies cetuximab and panitumumab. The added predictive value of additional biomarkers in the RAS-RAF-MAPK and PI3K-AKT-mTOR pathways in colorectal cancer is uncertain, which led us to systematically review the impact of alterations in KRAS (outside of exon 2), NRAS, BRAF, PIK3CA and PTEN in relation to the clinical benefit from anti-EGFR treatment.

METHODS

In total, 22 studies that include 2395 patients formed the basis for a meta-analysis on alterations in KRAS exons 3 and 4, NRAS, BRAF, and PIK3CA and PTEN and outcome of anti-EGFR treatment. Odds ratios for objective response rate (ORR) and hazard ratios (HR) for progression-free survival (PFS) and overall survival (OS) were calculated.

RESULTS

Mutations in KRAS exons 3 and 4, BRAF, PIK3CA and non-functional PTEN (mutations or loss of protein expression) significantly predicted poor ORR (OR = 0.26, OR = 0.29, OR = 0.39, and OR = 0.41, respectively). Significantly shorter PFS applied to mutations in KRAS exons 3 and 4 (HR = 2.19), NRAS (HR = 2.30) and BRAF (HR = 2.95) and non-functional PTEN (HR = 1.88). Significantly shorter OS applied to mutations in KRAS exons 3 and 4 (HR = 1.78), NRAS (HR = 1.85), BRAF (HR = 2.52), PIK3CA (HR = 1.43) and alterations in PTEN (HR = 2.09).

CONCLUSIONS

Meta-analysis suggests that mutations in KRAS exons 3 and 4, NRAS, BRAF and PIK3CA and non-functional PTEN predict resistance to anti-EGFR therapies and demonstrates that biomarker analysis beyond KRAS exon 2 should be implemented for prediction of clinical benefit from anti-EGFR antibodies in metastatic colorectal cancer.

Phase II trial of cetuximab plus irinotecan for oxaliplatin- and irinotecan-based chemotherapy-refractory patients with advanced and/or metastatic colorectal cancer: evaluation of efficacy and safety based on KRAS mutation status (T-CORE0801)

BACKGROUND

Mutations in the KRAS gene have been identified as negative predictors of response to anti-epidermal growth factor receptor (EGFR) monoclonal antibody therapy by patients with metastatic colorectal cancer (mCRC). However, it has been based on the study of mainly Caucasian mCRC patients. This prospective study investigated the relationship between the mutation status of EGFR-related genes including KRAS and the response rate (RR) to cetuximab plus irinotecan therapy in Japanese mCRC patients.

METHODS

Samples taken from 43 chemotherapy-refractory mCRC patients who had undergone cetuximab plus irinotecan therapy at 11 medical centers in Japan were subjected to direct DNA sequencing to determine the KRAS, BRAF, PIK3CA, NRAS, and AKT1 mutation status. The clinical outcome after the treatment was evaluated for each mutation status.

RESULTS

KRAS mutations were detected in 31.7% of 41 eligible patients. The RR to cetuximab plus irinotecan therapy was found to be 17.9 and 0% in the KRAS wild-type and mutant subgroups, respectively.

CONCLUSION

Despite the identification of a lower-than-expected RR to treatment by the KRAS wild-type subgroup, KRAS mutation status appears to be a useful predictive marker of response to cetuximab plus irinotecan therapy in Japanese mCRC patients.

Anti-epidermal growth factor receptor monoclonal antibody-based therapy for metastatic colorectal cancer: a meta-analysis of the effect of PIK3CA mutations in KRAS wild-type patients

INTRODUCTION

We conducted a meta-analysis to dissect the association between PIK3CA mutations (exon 9 and exon 20) and resistance to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MoAbs) in KRAS wild-type metastatic colorectal cancer (mCRC) patients.

MATERIAL AND METHODS

In 11 previously published studies, 864 cancer patients were treated with cetuximab or panitumumab-based therapy. Primary outcomes included objective response (complete response + partial response vs. stable disease + progressive disease), progression-free survival (PFS), and overall survival (OS). We calculated the odds ratio (OR) or hazard ratio (HR) with 95% confidence intervals (CIs) to estimate the risk or hazard. We found consistent and clinically substantial risk or hazard for objective response, PFS, and OS in the cetuximab or panitumumab-treated mCRC patients.

RESULTS

PIK3CA mutations as a whole were associated with reduced response and poor PFS and OS in KRAS wild-type mCRC patients (objective response: OR = 0.42 and 95% CI 0.23-0.75; PFS: HR = 1.54 and 95% CI 1.13-2.09; and OS: HR = 1.4 and 95% CI 1.02-1.91). PIK3CA exon 9 mutations had no effect, whereas exon 20 mutations were associated with a worse outcome compared with wild types, with an OR of 0.21 (95% CI 0.05-0.93).

CONCLUSIONS

PIK3CA mutations as a whole might be useful prognostic factors for assessing clinical outcomes of anti-EGFR MoAb-based chemotherapies in KRAS wild-type mCRC patients. In particular, PIK3CA exon 20 mutations were significantly associated with lack of response.

Genetic and epigenetic biomarkers for diagnosis, prognosis and treatment of colorectal cancer

Colorectal cancer (CRC) is one of the most common cancer worldwide and results from the accumulation of mutations and epimutations in colonic mucosa cells ultimately leading to cell proliferation and metastasis. Unfortunately, CRC prognosis is still poor and the search of novel diagnostic and prognostic biomarkers is highly desired to prevent CRC-related deaths. The present article aims to summarize the most recent findings concerning the use of either genetic or epigenetic (mainly related to DNA methylation) biomarkers for CRC diagnosis, prognosis, and response to treatment. Recent large-scale DNA methylation studies suggest that CRC can be divided into several subtypes according to the frequency of DNA methylation and those of mutations in key CRC genes, and that this is reflected by different prognostic outcomes. Increasing evidence suggests that the analysis of DNA methylation in blood or fecal specimens could represent a valuable non-invasive diagnostic tool for CRC. Moreover, a broad spectrum of studies indicates that the inter-individual response to chemotherapeutic treatments depends on both epigenetic modifications and genetic mutations occurring in colorectal cancer cells, thereby opening the way for a personalized medicine. Overall, combining genetic and epigenetic data might represent the most promising tool for a proper diagnostic, prognostic and therapeutic approach.

The dual pathway inhibitor rigosertib is effective in direct patient tumor xenografts of head and neck squamous cell carcinomas

The dual pathway inhibitor rigosertib inhibits phosphoinositide 3-kinase (PI3K) pathway activation as well as polo-like kinase 1 (PLK1) activity across a broad spectrum of cancer cell lines. The importance of PIK3CA alterations in squamous cell carcinoma of the head and neck (HNSCC) has raised interest in exploring agents targeting PI3K, the product of PIK3CA. The genetic and molecular basis of rigosertib treatment response was investigated in a panel of 16 HNSCC cell lines, and direct patient tumor xenografts from eight patients with HNSCC [four HPV-serotype16 (HPV16)-positive]. HNSCC cell lines and xenografts were characterized by pathway enrichment gene expression analysis, exon sequencing, gene copy number, Western blotting, and immunohistochemistry (IHC). Rigosertib had potent antiproliferative effects on 11 of 16 HPV(-) HNSCC cell lines. Treatment sensitivity was confirmed in two cell lines using an orthotopic in vivo xenograft model. Growth reduction after rigosertib treatment was observed in three of eight HNSCC direct patient tumor lines. The responsive tumor lines carried a combination of a PI3KCA-activating event (amplification or mutation) and a p53-inactivating event (either HPV16- or mutation-mediated TP53 inactivation). In this study, we evaluated the in vitro and in vivo efficacy of rigosertib in both HPV(+) and HPV(-) HNSCCs, focusing on inhibition of the PI3K pathway. Although consistent inhibition of the PI3K pathway was not evident in HNSCC, we identified a combination of PI3K/TP53 events necessary, but not sufficient, for rigosertib sensitivity.