Kirsten ras mutations in patients with colorectal cancer: the 'RASCAL II' study

Icotinib as initial treatment in lung adenocarcinoma patients with brain metastases

Background

To evaluate the antitumor activity and toxicity of icotinib as initial treatment in lung adenocarcinoma patients with brain metastases.

Methods

Twenty‐one patients with histologically or pathologically documented brain metastatic lung cancer were administered icotinib as initial treatment from 2011 to 2015 at the Cancer Institute and Hospital, Chinese Academy of Medical Sciences. Chemotherapy response was assessed by Response Evaluation Criteria in Solid Tumors and toxicity was evaluated according to National Cancer Institute‐Common Toxicity Criteria. Icotinib was administered three times per day at a dose of 125mg.

Results

The median overall and progression‐free survival rates were 15.2 (1.2–31.5 months, 95% confidence interval [CI] 6.6–23.7 months) and 8.9 months (0.6–30.5 months, 95% CI 3.4–14.3 months), respectively. The overall response and disease control rates were 61.9% and 90.5%, respectively. Icotinib was well tolerated, and no grade 3/4 adverse events were observed. The most common grade 1/2 adverse events included acneiform eruptions (38.1%), diarrhea (19.0%), and stomatitis (9.5%).

Conclusion

Icotinib is effective and well tolerated as initial treatment in lung adenocarcinoma patients with brain metastases.

KRAS G12V Mutation Detection by Droplet Digital PCR in Circulating Cell-Free DNA of Colorectal Cancer Patients

KRAS mutations are responsible for resistance to anti-epidermal growth factor receptor (EGFR) therapy in colorectal cancer patients. These mutations sometimes appear once treatment has started. Detection of KRAS mutations in circulating cell-free DNA in plasma (“liquid biopsy”) by droplet digital PCR (ddPCR) has emerged as a very sensitive and promising alternative to serial biopsies for disease monitoring. In this study, KRAS G12V mutation was analyzed by ddPCR in plasma DNA from 10 colorectal cancer patients and compared to six healthy donors. The percentage of KRAS G12V mutation relative to wild-type sequences in tumor-derived DNA was also determined. KRAS G12V mutation circulating in plasma was detected in 9 of 10 colorectal cancer patients whose tumors were also mutated. Colorectal cancer patients had 35.62 copies of mutated KRAS/mL plasma, whereas in healthy controls only residual copies were found (0.62 copies/mL, p = 0.0066). Interestingly, patients with metastatic disease showed a significantly higher number of mutant copies than M0 patients (126.25 versus 9.37 copies/mL, p = 0.0286). Wild-type KRAS was also significantly elevated in colorectal cancer patients compared to healthy controls (7718.8 versus 481.25 copies/mL, p = 0.0002). In conclusion, KRAS G12V mutation is detectable in plasma of colorectal cancer patients by ddPCR and could be used as a non-invasive biomarker.

Clinicopathologic and prognostic associations of KRAS and BRAF mutations in small intestinal adenocarcinoma

Activating KRAS and/or BRAF mutations have been identified as predictors of resistance to anti-epidermal growth factor receptor (EGFR) chemotherapy in colorectal cancer. But the status of KRAS and BRAF mutations and their clinicopathologic and prognostic significance has not been extensively evaluated in small intestinal adenocarcinomas. In this work, the KRAS and BRAF genes in 190 surgically resected small intestinal adenocarcinoma cases were sequenced and their association with various clinicopathologic variables, including survival of the patients, was analyzed. KRAS or BRAF mutations were observed in 63 (33%) cases. Sixty-one cases had KRAS mutations and 2 had BRAF mutations and the two types of mutation were mutually exclusive. The majority of KRAS mutations were G>A transition (43/61 cases, 71%) or p.G12D (31/61 cases, 51%). The patients with mutant KRAS tended to have higher pT classifications (P=0.034) and more frequent pancreatic invasion (P=0.020) than those with wild-type KRAS. Multivariate logistic regression analysis showed that certain mutated KRAS subtypes (G>A transitions and G12D mutations) were significantly correlated with higher pT classification (P=0.015 and 0.004, respectively) than wild-type KRAS and other KRAS mutations. The patients with KRAS or BRAF mutation had a tendency to shorter overall survival than those with wild-type KRAS and BRAF (P=0.148), but subgroup analysis demonstrated the patients with KRAS mutations showed worse survival (median, 46.0 months; P=0.046) than those with wild-type KRAS (85.4 months) in lower pT classification (pT1-pT3) group. In summary, KRAS and, infrequently, BRAF mutations are observed in a subset of small intestinal adenocarcinomas, and are associated with higher pT classification and more frequent pancreatic invasion. KRAS mutation is a poor prognostic predictor in patients with lower pT classification tumors. Anti-EGFR targeted therapy could be applied to about two-thirds of small intestinal adenocarcinoma patients, namely those with wild-type KRAS and BRAF if they have metastatic disease, similar to colorectal cancer patients.

Prognostic impact of KRAS mutation subtypes in 677 patients with metastatic lung adenocarcinomas

BACKGROUND

We previously demonstrated that patients with metastatic KRAS mutant lung cancers have a shorter survival compared with patients with KRAS wild-type cancers. Recent reports have suggested different clinical outcomes and distinct activated signaling pathways depending on KRAS mutation subtype. To better understand the impact of KRAS mutation subtype, we analyzed data from 677 patients with KRAS mutant metastatic lung cancer.

METHODS

We reviewed all patients with metastatic or recurrent lung cancers found to have KRAS mutations over a 6-year time period. We evaluated the associations among KRAS mutation type, clinical factors, and overall survival in univariate and multivariate analyses. Any significant findings were validated in an external multi-institution patient dataset.

RESULTS

Among 677 patients with KRAS mutant lung cancers (53 at codon 13, 624 at codon 12), there was no difference in overall survival for patients when comparing KRAS transition versus transversion mutations (p = 0.99), smoking status (p = 0.33), or when comparing specific amino acid substitutions (p = 0.20). In our dataset, patients with KRAS codon 13 mutant tumors (n = 53) had shorter overall survival compared with patients with codon 12 mutant tumors (n = 624) (1.1 versus 1.3 years, respectively; p = 0.009), and the findings were confirmed in a multivariate Cox model controlling for age, sex, and smoking status (hazard ratio: 1.52, 95% confidence interval: 1.11-2.08; p = 0.008). In an independent validation set of tumors from 682 patients with stage IV KRAS mutant lung cancers, there was no difference in survival between patients with KRAS codon 13 versus codon 12 mutations (1.0 versus 1.1 years, respectively; p = 0.41).

CONCLUSIONS

Among individuals with KRAS mutant metastatic lung cancers treated with conventional therapy, there are no apparent differences in outcome based on KRAS mutation subtype.

Pooled Analysis of the Prognostic and Predictive Value of KRAS Mutation Status and Mutation Subtype in Patients with Non-Small Cell Lung Cancer Treated with Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

OBJECTIVES

This pooled analysis of four trials of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) versus placebo was conducted to clarify the prognostic and predictive roles of Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations (MUTs) and to explore the importance of MUT subtype.

METHODS

Data were pooled from four trials of EGFR TKIs versus placebo (National Cancer Institute of Canada Clinical Trials Group [NCIC CTG] trial BR.21, TOPICAL, NCIC CTG trial BR.26, and NCIC CTG trial BR.19). Analyses of the combined data were performed to determine relationships of MUT status/subtype to response and survival end points.

RESULTS

KRAS status was known for 1362 of 2624 patients (785 receiving EGFR TKIs and 577 receiving placebo); 275 (20%) had KRAS MUTs (248 at codon 12; 15 at codon 13; 12 at other codons). In the placebo arms there was no difference in overall survival (OS) for patients with KRAS MUTs or wild-type tumors (hazard ratio [HR] = 1.04, confidence interval [CI]: 0.81-1.33 for univariable analysis and HR = 1.09, CI: 0.85-1.41 for multivariable analysis). Patients with guanine-to-thymidine transversion MUTs had longer OS than did those with guanine-to-adenine transition MUTs or guanine-to-cytosine transversion MUTs (median OS 6.3, 1.8, and 3.9 months, respectively, p = 0.01). Patients with KRAS MUT tumors derived no benefit from EGFR TKIs (OS HR = 1.13, CI: 0.85-1.51; progression-free survival HR = 1.02, CI: 0.76-1.36). The interaction between KRAS status and EGFR TKI effect was significant for progression-free survival (p = 0.04) but not for OS (p = 0.17). For patients with G12V MUTs, EGFR TKI treatment was harmful (OS HR = 1.96, CI: 1.03-3.70, p = 0.04), whereas guanine-to-adenine transition MUTs were associated with an OS benefit from EGFR TKIs (HR = 0.49, CI: 0.24-1.00, p = 0.05).

CONCLUSIONS

Overall, KRAS MUT is neither prognostic nor predictive of benefit from EGFR TKIs. However, it appears that KRAS MUT subtypes are not homogeneous in terms of their prognostic and predictive effects. These observations require prospective validation.

Pathophysiology and classification of pseudomyxoma peritonei

Background: The term pseudomyxoma peritonei (PMP) was first described in 1884 and there has been much debate since then over the term. A recent consensus of world experts agreed that PMP should be thought of as a clinical entity characterised by the presence of mucinous ascites, omental cake, peritoneal implants and possibly ovarian involvement. It generally originates from mucinous appendiceal tumours. Content: This review details the clinical presentation of this unusual condition, presents the new classification system and how this relates to outcome. The pathophysiology of this disease is also explored with a special reference to the relationship of the disease to tumour markers. Summary: A classification system has been agreed upon by the leading experts in PMP which is now divided into low and high grade mucinous carcinomatosis peritonei. This distinction correlates with clinical outcome as does the presence of raised tumour markers preoperatively. Outlook: Research needs to be focused on understanding the factors associated with poor prognosis through well designed multi-centred prospective studies. This will allow us to identify patients with bad tumour biology so that targeted treatment based on likely prognosis may then become a reality.

Locally advanced rectal cancers with simultaneous occurrence of KRAS mutation and high VEGF expression show invasive characteristics

In this study, we investigated the mutation status of KRAS gene in pretherapeutic and preoperative biopsies in 63 specimens of locally advanced rectal cancers in order to evaluate its potential predictive and/or prognostic role. Regions of interest of KRAS exon 2 were amplified and visualized on 2% agarose gel. Obtained PCR products were subjected to direct sequencing. KRAS mutations were detected in 35% of patients, 91% of which were located in codon 12 and 9% in codon 13. In general, KRAS mutation status did not affect the response to neoadjuvant chemoradiotherapy (CRT). However, patients harboring mutated KRAS gene, simultaneously with high vascular endothelial growth factor (VEGF) expression, exhibited a worse response to CRT (p=0.030), a more frequent appearance of local recurrences and distant metastasis (p=0.003), and shorter overall survival (p=0.001) compared to all others. On the contrary, patients with GGT>GCT KRAS mutation exhibited a significantly better response to CRT than those with any other type of KRAS mutation (p=0.017). Moreover, the presence of GGT>GCT mutation was associated with low VEGF and Ki67 expression (p=0.012 in both cases), parameters related to less aggressiveness of the disease. Our results suggest that KRAS mutation status could have some predictive and prognostic importance in rectal cancer when analyzed together with other parameters, such as VEGF and Ki67 expression. In addition, it seems that not only the presence but the type of KRAS mutation is important for examining its impact on CRT response.

The impact of KRAS mutations on prognosis in surgically resected colorectal cancer patients with liver and lung metastases: a retrospective analysis

Background

KRAS mutations are common in colorectal cancer (CRC). The role of KRAS mutation status as a prognostic factor remains controversial, and most large population-based cohorts usually consist of patients with non-metastatic CRC. We evaluated the impact of KRAS mutations on the time to recurrence (TTR) and overall survival (OS) in patients with metastatic CRC who underwent curative surgery with perioperative chemotherapy.

Methods

Patients who underwent curative resection for primary and synchronous metastases were retrospectively collected in a single institution during a 6 year period between January 2008 and June 2014. Patients with positive surgical margins, those with known BRAF mutation, or those with an unknown KRAS mutation status were excluded, and a total of 82 cases were identified. The pathological and clinical features were evaluated. Patients’ outcome with KRAS mutation status for TTR and OS were investigated by univariate and multivariate analysis.

Results

KRAS mutations were identified in 37.8 % of the patients and not associated with TTR or OS between KRAS wild type and KRAS mutation cohorts (log-rank p = 0.425 for TTR; log-rank p = 0.137 for OS). When patients were further subdivided into three groups according to mutation subtype (wild-type vs. KRAS codon 12 mutation vs. KRAS codon 13 mutation) or amino acid missense mutation type (G > A vs. G > T vs. G > C), there were no significant differences in TTR or OS. Mutational frequencies were significantly higher in patients with lung metastases compared with those with liver and ovary/bladder metastases (p = 0.039), however, KRAS mutation status was not associated with an increased risk of relapsed in the lung.

Conclusions

KRAS mutation was not associated with TTR or OS in patients with metastatic CRC who underwent curative surgery with perioperative chemotherapy.

KRAS mutation in lung metastases from colorectal cancer: prognostic implications

KRAS mutant colorectal cancer (CRC) patients develop lung and brain metastases more frequently than KRAS wild-type (WT) counterpart. We retrospectively investigated the prognostic role of KRAS, BRAF, and PIK3CA (exon 20) mutations and loss of phosphatase and tensin homolog (PTEN) in surgically resected lung metastases. Lung specimens from 75 metastatic CRC (mCRC) patients treated with one or more metastasectomies with curative intent were analyzed. Sixty-four percent of patients had KRAS WT lung metastases. PTEN loss-of-function was found in 75%. BRAF and PIK3CA exon 20 mutations were not found. Seven patients subsequently developed brain metastases and 43% of them had KRAS mutation. In univariate analysis, median overall survival (OS) for KRAS WT patients was longer, compared to KRAS mutant patients (median 60.9 vs. 36.6 months, P = 0.035). In addition, both progression-free survival (PFS) and lung disease-free survival (LDFS) between lung surgery and relapse were not associated with KRAS and PTEN status. In multivariate analysis, the risk of death was significantly increased by KRAS mutational status (OS Hazard ratio (HR) 2.17, 95% IC 1.19-3.96, P = 0.012) and lack of adjuvant chemotherapy (OS HR 0.10, 95% IC 0.01-0.74, P = 0.024). The proportion of KRAS mutations in lung metastases was similar to the expected proportion in primary tumors. Patients harboring KRAS mutation had a poorer survival rate compared to WT group both in univariate and multivariate analysis. Moreover, administration of adjuvant chemotherapy after lung metastasectomy (LM) significantly improved both PFS and OS. KRAS mutation is a negative prognostic factor in mCRC patients undergoing LM. Further larger and prospective studies are necessary to confirm these findings.

Correlation between Gene Variants, Signaling Pathways, and Efficacy of Chemotherapy Drugs against Colon Cancers

Efficacies, toxicities, and resistance mechanisms of chemotherapy drugs, such as oxaliplatin and 5-fluorouracil (5-FU), vary widely among various categories and subcategories of colon cancers. By understanding the differences in the drug efficacy and resistance at the level of protein–protein networks, we identified the correlation between the drug activity of oxaliplatin/5-FU and gene variations from the US National Cancer Institute-60 human cancer cell lines. The activity of either of these drugs is correlated with specific amino acid variant(s) of KRAS and other genes from the signaling pathways of colon cancer progression. We also discovered that the activity of a non-DNA-binding novel platinum drug, phosphaplatin, is comparable with oxaliplatin and 5-FU when it was tested against colon cancer cell lines. Our strategy that combines the knowledge from pharmacogenomics across cell lines with the molecular information from specific cancer cells is beneficial for predicting the outcome of a possible combination therapy for personalized treatment.

Carrier molecules and extraction of circulating tumor DNA for next generation sequencing in colorectal cancer

The aims of the study were: i) to compare circulating tumor DNA (ctDNA) yields obtained by different manual extraction procedures, ii) to evaluate the addition of various carrier molecules into the plasma to improve ctDNA extraction recovery, and iii) to use next generation sequencing (NGS) technology to analyze KRAS, BRAF, and NRAS somatic mutations in ctDNA from patients with metastatic colorectal cancer. Venous blood was obtained from patients who suffered from metastatic colorectal carcinoma. For plasma ctDNA extraction, the following carriers were tested: carrier RNA, polyadenylic acid, glycogen, linear acrylamide, yeast tRNA, salmon sperm DNA, and herring sperm DNA. Each extract was characterized by quantitative real-time PCR and next generation sequencing. The addition of polyadenylic acid had a significant positive effect on the amount of ctDNA eluted. The sequencing data revealed five cases of ctDNA mutated in KRAS and one patient with a BRAF mutation. An agreement of 86% was found between tumor tissues and ctDNA. Testing somatic mutations in ctDNA seems to be a promising tool to monitor dynamically changing genotypes of tumor cells circulating in the body. The optimized process of ctDNA extraction should help to obtain more reliable sequencing data in patients with metastatic colorectal cancer.

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

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

Association Between Specific Mutations in KRAS Codon 12 and Colorectal Liver Metastasis

IMPORTANCE

Currently, one of the most commonly available biomarkers in the treatment of patients with colorectal liver metastases (CRLM) is the Kirsten rat sarcoma viral oncogene homolog (KRAS); however, the prognostic implications of specific mutations of the KRAS gene are still not well defined.

OBJECTIVE

To investigate the prognostic impact of specific KRAS mutations on patients undergoing liver resection for CRLM.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective single-center study was conducted from January 1, 2003, to December 31, 2013. Data about specific KRAS mutations for 331 patients who underwent hepatic resection for CRLM at Johns Hopkins Hospital between 2003 and 2013 were analyzed. Clinicopathological characteristics, perioperative details, and outcomes were stratified by specific KRAS mutation at codons 12 and 13.

INTERVENTION

Resection of CRLM.

MAIN OUTCOMES AND MEASURES

Overall survival (OS) and recurrence-free survival.

RESULTS

A mutated KRAS (mtKRAS) was identified in 91 patients (27.5%). At a median follow-up of 27.4 months, recurrence was observed in 48 patients (52.7%) with mtKRAS and 130 patients (54.2%) with wild-type KRAS (wtKRAS) (P = .82). Median and 5-year survival among patients with mtKRAS was 32.4 months and 32.7%, respectively, vs 58.5 months and 46.9%, respectively, for patients with wtKRAS (P = .02). Patients with KRAS codon 12 mutations had worse OS (hazard ratio [HR], 1.54; 95% CI, 1.05-2.27; P = .03) vs those with wtKRAS, whereas a KRAS codon 13 mutation was not associated with prognosis (HR, 1.47; 95% CI, 0.83-2.62; P = .19). Among the 6 most common mutations in codons 12 and 13, only G12V (HR, 1.78; 95% CI, 1.00-3.17; P = .05) and G12S (HR, 3.33; 95% CI, 1.22-9.10; P = .02) were associated with worse OS compared with patients with wtKRAS (both P < .05). Among patients who recurred, G12V (HR, 2.96; 95% CI, 1.32-6.61; P = .01), G12C (HR, 6.74; 95% CI, 2.05-22.2; P = .002), and G12S mutations (HR, 4.91; 95% CI, 1.52-15.8; P = .01) were associated with worse OS (both P < .05).

CONCLUSIONS AND RELEVANCE

G12V and G12S mutations of codon 12 were independent prognostic factors of worse OS. Among patients who recurred after resection of CRLM, G12V, G12C, and G12S mutations were associated with worse OS. Information on specific KRAS mutations may help individualize therapeutic and surveillance strategies for patients with resected CRLM.

Impact of mutational status on survival in low-grade serous carcinoma of the ovary or peritoneum

BACKGROUND

Low-grade serous carcinoma of the ovary or peritoneum is a distinct, well- recognized histologic subtype characterized by young age at diagnosis, relative chemoresistance, and prolonged overall survival. Common mutations reported to be found within this subtype include KRAS and BRAF.

METHODS

Using clinical information of patients from our IRB-approved registry and tissue from a subset of these patients, we performed mutational analysis for KRAS and BRAF using the direct Sanger sequencing technique and correlated findings with the clinical outcome, overall survival (OS).

RESULTS

In 79 cases, patients with KRAS or BRAF mutations (n=21) had a significantly better OS than those with wild-type KRAS or BRAF (n=58) (106.7 months (95% CI, 50.6, 162.9) vs 66.8 months (95% CI, 43.6, 90.0)), respectively (P=0.018).

CONCLUSIONS

Mutational status appears to be a potential prognostic factor in low-grade serous carcinoma of the ovary or peritoneum.

Defining an optimal surgical strategy for synchronous colorectal liver metastases: staged versus simultaneous resection?

BACKGROUND

We aimed to assess if simultaneous resection conferred any survival benefit in resection of synchronous colorectal liver metastases.

METHODS

From January 1990 to December 2008, 116 patients with synchronous colorectal liver metastases were identified. Among these 116 patients, 88 underwent staged resection (SR), while the remaining 28 patients underwent simultaneous resection (SIMR). Patients' follow-up data were reviewed.

RESULTS

There were no significant differences between the groups in terms of patient and tumour characteristics. Major hepatectomy was performed in 54 patients (61%) undergoing SR, and 12 patients (43%) undergoing SIMR (P = 0.09). The median blood loss (SR 0.7 L versus SIMR 0.8 L) was similar. Post-operative morbidity rates and hospital mortality rates were not statistically different. The total length of hospital stay was shorter in SIMR patients (18.0 versus 11.5 days, P = 0.009). The 1-, 3- and 5-year overall survival for SR were 90.7%, 47.1% and 33.3%, whilst the corresponding survival rates for SIMR were 75.0%, 25.0% and 0%, respectively (P = 0.003). However, when the disease-free survival (DFS) was stratified according to the number of hepatic metastases, the survival benefit of SR and SIMR for solitary CRM were similar (3-year DFS: 28.3% versus 11.1%, P = 0.089).

CONCLUSIONS

Our study showed that an operative strategy of SR generally offered better survival outcome than SIMR in the surgical management of CRM.

Prognostic role of KRAS, NRAS, BRAF and PIK3CA mutations in advanced colorectal cancer

AIM

To explore the prognostic value of extended mutational profiling for metastatic colorectal cancer (mCRC).

MATERIALS & METHODS

We retrospectively reviewed survival results of 194 mCRC patients that were assigned to four molecular subgroups: BRAF mutated; KRAS mutated codons 12-13 only; any of KRAS codons 61-146, PIK3CA or NRAS mutations and all wild-type. Point mutations were investigated by pyrosequencing.

RESULTS

BRAF (5.2%) and KRAS 12-13 (31.9%) mutations were associated with poorer survival (HR 2.8 and 1.76, respectively). Presenting with right-sided colon cancer, not resected primary tumor, WBC >10 × 10(9)/l, receiving less chemotherapy or no bevacizumab were all associated with inferior outcome. The all-wild-type subgroup (39.2%) reported the longest survival.

CONCLUSION

Extended mutational profile combined with clinical factors may impact on survival in mCRC.

Molecular profiling in the treatment of colorectal cancer: focus on regorafenib

Metastatic colorectal cancer (mCRC) is a highly heterogeneous disease. Its treatment outcome has been significantly improved over the last decade with the incorporation of biological targeted therapies, including anti-EGFR antibodies, cetuximab and panitumumab, and VEGF inhibitors, bevacizumab, ramucirumab, and aflibercept. The identification of predictive biomarkers has further improved the survival by accurately selecting patients who are most likely to benefit from these treatments, such as RAS mutation profiling for EGFR antibodies. Regorafenib is a multikinase inhibitor currently used as late line therapy for mCRC. The molecular and genetic markers associated with regorafenib treatment response are yet to be characterized. Here, we review currently available clinical evidence of mCRC molecular profiling, such as RAS, BRAF, and MMR testing, and its role in targeted therapies with special focus on regorafenib treatment.

Bevacizumab with chemotherapy in patients with KRAS wild-type metastatic colorectal cancer: Czech registry data

AIM

This retrospective analysis investigated the effectiveness of combination therapy with bevacizumab and chemotherapy in the first-line treatment of patients with KRAS wild-type metastatic colorectal cancer.

PATIENTS & METHODS

Patients with KRAS wild-type metastatic colorectal cancer in the CORECT registry who initiated treatment with bevacizumab between 2008 and 2012 were enrolled. Overall survival and progression-free survival were the main effectiveness end points.

RESULTS

A total of 981 patients were enrolled. Median progression-free survival was 11.3 months (95% CI: 10.7-11.8) and median overall survival was 28.4 months (95% CI: 26.2-30.6). The most common adverse events were thromboembolic disease (4%) and hypertension (3.5%).

CONCLUSION

This retrospective analysis shows the effectiveness of bevacizumab with chemotherapy in patients with KRAS wild-type metastatic colorectal cancer.

Pharmacogenomics of cetuximab in metastatic colorectal carcinoma

Cetuximab is a chimeric monoclonal antibody that has revolutionized the treatment of metastatic colorectal cancer. Knowledge of the mechanisms that underlie its effectiveness, as well as the primary and secondary resistance mechanisms, have led to important developments in the understanding of cetuximab biology. In light of knowledge gained from recent trials, the efficacy of cetuximab has been clearly demonstrated to depend upon RAS mutational status, moreover cetuximab should only be used in a subset of patients who may benefit. In this article, we critically review clinical and pharmacogenetic issues of cetuximab, focusing on the cost-effectiveness involved with the use of the drug.

KRAS Mutation Status Is Not a Predictor for Tumor Response and Survival in Rectal Cancer Patients Who Received Preoperative Radiotherapy With 5-Fluoropyrimidine Followed by Curative Surgery

We evaluated the tumor response and survival according to the KRAS oncogene status in locally advanced rectal cancer. One hundred patients with locally advanced rectal cancer (cT3-4N0-2M0) received preoperative radiation of 50.4 Gy in 28 fractions with 5-fluorouracil and total mesorectal excision. Tumor DNA from each patient was obtained from pretreatment biopsy tissues. A Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation was found in 26 (26%) of the 100 patients. Downstaging (ypT0-2N0M0) rates after preoperative chemoradiotheray were not statistically different between the wild-type and mutant-type KRAS groups (30.8% vs 27.0%, P = 0.715, respectively). After a median follow-up time of 34 months, there was no statistically significant difference in the 3-year relapse-free survival (82.2% vs 82.6%, P = 0.512) and overall survival (94.7% vs 92.3%, P = 0.249) rates between wild-type and mutant-type KRAS groups, respectively. The KRAS mutation status does not influence the tumor response to the radiotherapy and survival in locally advanced rectal cancer patients who received preoperative chemoradiotherapy and curative surgery.

Genetic markers of recurrence in colorectal cancer

Colorectal cancer (CRC) worldwide belongs to one of the most frequent cancers affecting both genders. Surgery and 5-fluorouracil-based adjuvant chemotherapy are recommended for patients with high-risk stage II and stage III colon carcinoma. Mutations of genes encoding for specific proteins may have an impact on the time to recurrence. These proteins act over specific signaling pathways, are implicated in metabolic processes and regulate the cell cycle. Though many retrospective studies show strong associations between genetic mutations and the clinical outcome of patients with CRC, currently no validated biomarkers are used in clinical routine settings. Therefore, large prospective validation studies should be carried out in order to strengthen the position of genetic mutations in personalized treatment of patients with CRC.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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 mutation testing of tumours in adults with metastatic colorectal cancer: a systematic review and cost-effectiveness analysis

BACKGROUND

Bowel cancer is the third most common cancer in the UK. Most bowel cancers are initially treated with surgery, but around 17% spread to the liver. When this happens, sometimes the liver tumour can be treated surgically, or chemotherapy may be used to shrink the tumour to make surgery possible. Kirsten rat sarcoma viral oncogene (KRAS) mutations make some tumours less responsive to treatment with biological therapies such as cetuximab. There are a variety of tests available to detect these mutations. These vary in the specific mutations that they detect, the amount of mutation they detect, the amount of tumour cells needed, the time to give a result, the error rate and cost.

OBJECTIVES

To compare the performance and cost-effectiveness of KRAS mutation tests in differentiating adults with metastatic colorectal cancer whose metastases are confined to the liver and are unresectable and who may benefit from first-line treatment with cetuximab in combination with standard chemotherapy from those who should receive standard chemotherapy alone.

DATA SOURCES

Thirteen databases, including MEDLINE and EMBASE, research registers and conference proceedings were searched to January 2013. Additional data were obtained from an online survey of laboratories participating in the UK National External Quality Assurance Scheme pilot for KRAS mutation testing.

METHODS

A systematic review of the evidence was carried out using standard methods. Randomised controlled trials were assessed for quality using the Cochrane risk of bias tool. Diagnostic accuracy studies were assessed using the QUADAS-2 tool. There were insufficient data for meta-analysis. For accuracy studies we calculated sensitivity and specificity together with 95% confidence intervals (CIs). Survival data were summarised as hazard ratios and tumour response data were summarised as relative risks, with 95% CIs. The health economic analysis considered the long-term costs and quality-adjusted life-years associated with different tests followed by treatment with standard chemotherapy or cetuximab plus standard chemotherapy. The analysis took a 'no comparator' approach, which implies that the cost-effectiveness of each strategy will be presented only compared with the next most cost-effective strategy. The de novo model consisted of a decision tree and Markov model.

RESULTS

The online survey indicated no differences between tests in batch size, turnaround time, number of failed samples or cost. The literature searches identified 7903 references, of which seven publications of five studies were included in the review. Two studies provided data on the accuracy of KRAS mutation testing for predicting response to treatment in patients treated with cetuximab plus standard chemotherapy. Four RCTs provided data on the clinical effectiveness of cetuximab plus standard chemotherapy compared with that of standard chemotherapy in patients with KRAS wild-type tumours. There were no clear differences in the treatment effects reported by different studies, regardless of which KRAS mutation test was used to select patients. In the 'linked evidence' analysis the Therascreen KRAS RGQ PCR Kit (QIAGEN) was more expensive but also more effective than pyrosequencing or direct sequencing, with an incremental cost-effectiveness ratio of £17,019 per quality-adjusted life-year gained. In the 'assumption of equal prognostic value' analysis the total costs associated with the various testing strategies were similar.

LIMITATIONS

The results assume that the differences in outcomes between the trials were solely the result of the different mutation tests used to distinguish between patients; this assumption ignores other factors that might explain this variation.

CONCLUSIONS

There was no strong evidence that any one KRAS mutation test was more effective or cost-effective than any other test.

STUDY REGISTRATION

PROSPERO CRD42013003663.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

ITF-2B protein levels are correlated with favorable prognosis in patients with colorectal carcinomas

The majority of sporadic forms of colorectal carcinomas is characterized by deregulation of Wnt/β-catenin signaling early in colorectal carcinogenesis. As a consequence, ITF-2B protein levels are increased in adenomas of these patients. However, ITF-2B protein levels are strongly reduced with increasing carcinoma stages, suggesting that reduction of ITF-2B protein is required for progression of adenomas to colorectal carcinomas. To find out if ITF-2B protein levels are correlated with the survival of patients with colorectal carcinomas, a tissue microarray containing samples from 213 colorectal carcinomas (T-categories T2 and T3) with corresponding survival information was stained with an ITF-2B antibody. In addition, we analyzed if detection of ITF-2B in microsatellite instable and microsatellite stable carcinomas as well as in colorectal carcinomas with KRAS mutations is correlated with survival. Detection of cytoplasmic ITF-2B protein was associated with better overall and progression free survival of patients with colorectal carcinomas (P=0.033 and 0.024, respectively). Multivariate Cox regression analysis revealed an increased risk to suffer from poor overall survival and recurrent disease if no cytoplasmic ITF-2B was detectable (HR=1.91; P=0.033 and HR=1.75; P=0.033, respectively). Similarly, patients with MSS carcinomas had a better overall survival, if they showed cytoplasmic positivity for ITF-2B (P=0.013). Remarkably, patients with colorectal carcinomas carrying KRAS mutations had a better overall and progression free survival rate if the carcinomas were positive for cytoplasmic ITF-2B (HR=4.71; P=0.002 and HR=2.57; P=0.024, respectively). These data suggest that cytoplasmic protein levels of ITF-2B could be used as a prognostic marker for patients with colorectal carcinomas.

Tumor oncogene (KRAS) status and risk of venous thrombosis in patients with metastatic colorectal cancer

BACKGROUND

Patients with metastatic colon cancer (mCRC) are at increased risk of venous thromboembolism (VTE). Limited preclinical data suggest that the oncogene (KRAS) mutational status of the tumor represents a plausible clinical link to systemic hypercoagulability in cancer patients.

OBJECTIVES

To determine if a tumor genetic characteristic, KRAS mutational status, is associated with an increased risk of VTE in patients with mCRC.

PATIENTS/METHODS

A retrospective cohort study of patients with mCRC and KRAS test results was conducted at multiple practice sites across New England in the United States. The primary outcome was a VTE event, defined as deep venous thrombosis (DVT) and/or pulmonary embolism (PE), either 6 months before or at any time after the diagnosis of mCRC. KRAS status (mutated vs. wild type) and other relevant predictors of thrombosis were collected.

RESULTS

Of 172 histologically confirmed patients with mCRC, 40 developed a VTE (23.3%). Sixty-five patients (37.8%) had a mutant KRAS status. The incidence of VTE and DVT among patients with mutated KRAS was 32.3 and 23.1%, respectively. The corresponding incidence among patients with wild-type KRAS was 17.8 and 9.4%. Odd ratios for the association were 2.21 (95% CI, 1.08-4.53) for VTE and 2.62 (95% CI, 1.12-6.12) for DVT, and remained significant despite adjustment for Khorana score and bevacizumab use.

CONCLUSION

Tumor mutant KRAS status is associated with an increased risk of VTE in patients with mCRC. The tumor genetic profile may represent a novel and important risk factor for thrombosis in patients with cancer.

Colorectal Cancer Biomarkers: Where Are We Now?

Colorectal cancer is one of the major causes of cancer-related death in the Western world. Patient survival is highly dependent on the tumor stage at the time of diagnosis. Reduced sensitivity to chemotherapy is still a major obstacle in effective treatment of advanced disease. Due to the fact that colorectal cancer is mostly asymptomatic until it progresses to advanced stages, the implementation of screening programs aimed at early detection is essential to reduce incidence and mortality rates. Current screening and diagnostic methods range from semi-invasive procedures such as colonoscopy to noninvasive stool-based tests. The combination of the absence of symptoms, the semi-invasive nature of currently used methods, and the suboptimal accuracy of fecal blood tests results in colorectal cancer diagnosis at advanced stages in a significant number of individuals. Alterations in gene expression leading to colorectal carcinogenesis are reflected in dysregulated levels of nucleic acids and proteins, which can be used for the development of novel, minimally invasive molecular biomarkers. The purpose of this review is to discuss the commercially available colorectal cancer molecular diagnostic methods as well as to highlight some of the new candidate predictive and prognostic molecular markers for tumor, stool, and blood samples.

Pathological response after neoadjuvant bevacizumab- or cetuximab-based chemotherapy in resected colorectal cancer liver metastases

Neoadjuvant chemotherapy (NACT) prior to liver resection is advantageous for patients with colorectal cancer liver metastases (CLM). Bevacizumab- or cetuximab-based NACT may affect patient outcome and curative resection rate, but comparative studies on differential tumour regression grade (TRG) associated with distinct antibodies-associated regimens are lacking. Ninety-three consecutive patients received NACT plus bevacizumab (n = 46) or cetuximab (n = 47) followed by CLM resection. Pathological response was determined in each resected metastasis as TRG rated from 1 (complete) to 5 (no response). Except for KRAS mutations prevailing in bevacizumab versus cetuximab (57 vs. 21 %, p = 0.001), patients characteristics were well balanced. Median follow-up was 31 months (IQR 17-48). Bevacizumab induced significantly better pathological response rates (TRG1-3: 78 vs. 34 %, p < 0.001) as well as complete responses (TRG1: 13 vs. 0 %, p = 0.012) with respect to cetuximab. Three-year progression-free survival (PFS) and overall survival (OS) were not significantly different in the two cohorts. At multivariable analysis, significant association with pathological response was found for number of resected metastases (p = 0.015) and bevacizumab allocation (p < 0.001), while KRAS mutation showed only a trend. Significant association with poorer PFS and OS was found for low grades of pathological response (p = 0.009 and p < 0.001, respectively), R2 resection or presence of extrahepatic disease (both p < 0.001) and presence of KRAS mutation (p = 0.007 and p < 0.001, respectively). Bevacizumab-based regimens, although influenced by the number of metastases and KRAS status, improve significantly pathological response if compared to cetuximab-based NACT. Possible differential impact among regimens on patient outcome has still to be elucidated.

Prediagnostic Physical Activity and Colorectal Cancer Survival: Overall and Stratified by Tumor Characteristics

BACKGROUND

Physical activity is associated with a lower incidence of colorectal cancer; however, the relationship of physical activity with colorectal cancer survival is not yet clear. We evaluated the association between prediagnostic physical activity and colorectal cancer survival, overall and accounting for tumor markers associated with colorectal cancer survival: BRAF and KRAS mutation status and microsatellite instability (MSI) status.

METHODS

Participants were 20- to 74-year-old colorectal cancer patients diagnosed between 1998 and 2007 from the population-based Seattle Colon Cancer Family Registry (S-CCFR). Self-reported physical activity in the years preceding colorectal cancer diagnosis was summarized as average metabolic equivalent task hours per week (MET-h/wk; n = 1,309). Somatic BRAF and KRAS mutations and MSI status were evaluated on a subset of patients (n = 1043). Cox regression was used to estimate HRs and 95% confidence intervals (CI) for overall and disease-specific survival after adjusting for relevant confounders. Stratified analyses were conducted across categories of BRAF, KRAS, and MSI, as well as tumor stage and site.

RESULTS

Higher prediagnostic recreational physical activity was associated with significantly more favorable overall survival (HR for highest vs. lowest category, 0.70; 95% CI, 0.52-0.96); associations were similar for colorectal cancer-specific survival. Results consistently indicated a favorable association with physical activity across strata defined by tumor characteristics.

CONCLUSION

Individuals who were physically active before colorectal cancer diagnosis experienced better survival than those who were inactive or minimally active.

IMPACT

Our results support existing physical activity recommendations for colorectal cancer patients and suggest that the beneficial effect of activity is not specific to a particular molecular phenotype of colorectal cancer.

A randomized Phase II clinical study of combining panitumumab and bevacizumab, plus irinotecan, 5-fluorouracil, and leucovorin (FOLFIRI) compared with FOLFIRI alone as second-line treatment for patients with metastatic colorectal cancer and KRAS mutation

BACKGROUND

This study investigated the efficacy and safety of a new treatment strategy of combining panitumumab and bevacizumab, plus irinotecan, 5-fluorouracil, and leucovorin (FOLFIRI) versus FOLFIRI alone as second-line chemotherapy for metastatic colorectal cancer (mCRC) patients with known V-Ki-ras2 Kirsten rat sarcoma viral oncogene (KRAS) mutation status.

METHODS

Patients with mCRC who had known KRAS tumor status and unsuccessful previous oxaliplatin-based chemotherapy were included in the study. They were randomly assigned to two groups to receive panitumumab and bevacizumab plus FOLFIRI, or FOLFIRI alone. In panitumumab and bevacizumab plus FOLFIRI group, patients were given 4 mg/kg panitumumab and bevacizumab plus FOLFIRI every 2 weeks.

RESULTS

In all, 65 patients were assigned to panitumumab and bevacizumab plus FOLFIRI group, and 77 to FOLFIRI alone group. For WT KRAS patients, the median progression-free survival (PFS) was 5.7 months (95% confidence interval [CI], 2.4-7.5 months) for panitumumab and bevacizumab plus FOLFIRI and 3.8 months (95% CI, 3.0-6.7 months) for FOLFIRI alone; median overall survival (OS) was 15.2 months (95% CI, 8.9-19.7 months) for panitumumab and bevacizumab plus FOLFIRI and 11.0 months (95% CI, 8.2-15.4 months) for FOLFIRI alone. For MU KRAS patients, median PFS was 5.1 months (95% CI, 2.7-10.2 months) for panitumumab and bevacizumab plus FOLFIRI and 4.1 months (95% CI, 2.5-8.4 months) for FOLFIRI alone; median OS was 12.8 months (95% CI, 7.8-15.8 months) for panitumumab and bevacizumab plus FOLFIRI and 10.5 months (95% CI, 6.1-15.3 months) for FOLFIRI alone. Grade 3 and 4 adverse events were associated with panitumumab and bevacizumab plus FOLFIRI but tolerable among patients.

CONCLUSION

Patients with mCRC can be safely and efficiently treated with second-line chemotherapy of combining panitumumab and bevacizumab plus FOLFIRI, despite their KRAS mutation status.

Cancer risk and overall survival in mismatch repair proficient hereditary non-polyposis colorectal cancer, Lynch syndrome and sporadic colorectal cancer

Mismatch repair proficient hereditary non-polyposis colorectal cancer (MSS-HNPCC) encloses a heterogeneous group of families consisting of different unknown genetic syndromes and/or aggregations cases. The lack of information about the hereditability of cancer risk in these families makes it difficult to carry out an individualized Genetic Counseling. Therefore, deep description of such families becomes important for a better classification and search for underlying susceptibility causes. The aim of this study is to describe and compare the clinical, morphological features, tumor KRAS status and overall survival in MSS-HNPCC, Lynch and sporadic colorectal cancer. A total of 37 MSS-HNPCC families, 50 Lynch families and 612 sporadic CRC were included. Clinical and morphological data were evaluated by reviewing medical and pathology reports of 55, 69 and 102 tumors respectively. KRAS/BRAF status were detected by allele specific real-time PCR. Standardized incidence ratios (SIR) were calculated among 602 MSS-HNPCC relatives and 668 Lynch relatives. Main features distinguishing MSS-HNPCC were diagnosis age (55.1 ± 12.6), preferential distal location (76%), polyp detection (45%) and familial colorectal cancer incidence (SIR = 6.6). In addition, we found increased incidences rates for kidney, stomach and uterus tumors. KRAS mutation rates were similar in the study populations (48.8 ± 5.8) but higher than those described before by Sanger sequencing. MSS-HNPCC overall survival was similar to Lynch in B Dukes' stage tumors and between Lynch and sporadic in C stage tumors. Anatomical and morphological data of MSS-HNPCC are consistent with other described populations. Our studies disclose an increased HNPCC-extracolonic tumors incidence and improved overall survival in MSS-HNPCC families.

BRAF and RAS mutations as prognostic factors in metastatic colorectal cancer patients undergoing liver resection

Background:

Despite major advances in the management of metastatic colorectal cancer (mCRC) with liver-only involvement, relapse rates are high and reliable prognostic markers are needed.

Methods:

To assess the prognostic impact of BRAF and RAS mutations in a large series of liver-resected patients, medical records of 3024 mCRC patients were reviewed. Eligible cases undergoing potentially curative liver resection were selected. BRAF and RAS mutational status was tested on primary and/or metastases by means of pyrosequencing and mass spectrometry genotyping assay. Primary endpoint was relapse-free survival (RFS).

Results:

In the final study population (N=309) BRAF mutant, RAS mutant and all wild-type (wt) patients were 12(4%), 160(52%) and 137(44%), respectively. Median RFS was 5.7, 11.0 and 14.4 months respectively and differed significantly (Log-rank, P=0.043). At multivariate analyses, BRAF mutant had a higher risk of relapse in comparison to all wt (multivariate hazard ratio (HR)=2.31; 95% CI, 1.09–4.87; P=0.029) and to RAS mutant (multivariate HR=2.06; 95% CI, 1.02–4.14; P=0.044). Similar results were obtained in terms of overall survival. Compared with all wt patients, RAS mutant showed a higher risk of death (HR=1.47; 95% CI, 1.05–2.07; P=0.025), but such effect was lost at multivariate analyses.

Conclusions:

BRAF mutation is associated with an extremely poor median RFS after liver resection and with higher probability of relapse and death. Knowledge of BRAF mutational status may optimise clinical decision making in mCRC patients potentially candidate to hepatic surgery. RAS status as useful marker in this setting might require further studies.

KRAS and BRAF mutations are prognostic biomarkers in patients undergoing lung metastasectomy of colorectal cancer

Background:

We evaluated KRAS (mKRAS (mutant KRAS)) and BRAF (mBRAF (mutant BRAF)) mutations to determine their prognostic potential in assessing patients with colorectal cancer (CRC) for lung metastasectomy.

Methods:

Data were reviewed from 180 patients with a diagnosis of CRC who underwent a lung metastasectomy between January 1998 and December 2011.

Results:

Molecular analysis revealed mKRAS in 93 patients (51.7%), mBRAF in 19 patients (10.6%). In univariate analyses, overall survival (OS) was influenced by thoracic nodal status (median OS: 98 months for pN−, 27 months for pN+, P<0.0001), multiple thoracic metastases (75 months vs 101 months, P=0.008) or a history of liver metastases (94 months vs 101 months, P=0.04). mBRAF had a significantly worse OS than mKRAS and wild type (WT) (P<0.0001). The 5-year OS was 0% for mBRAF, 44% for mKRAS and 100% for WT, with corresponding median OS of 15, 55 and 98 months, respectively (P<0.0001). In multivariate analysis, WT BRAF (HR: 0.005 (95% CI: 0.001–0.02), P<0.0001) and WT KRAS (HR: 0.04 (95% CI: 0.02–0.1), P<0.0001) had a significant impact on OS.

Conclusions:

mKRAS and mBRAF seem to be prognostic factors in patients with CRC who undergo lung metastasectomy. Further studies are necessary.

Colorectal carcinomas with KRAS codon 12 mutation are associated with more advanced tumor stages

BACKGROUND

KRAS mutation occurs in 35%-40% of colorectal cancer (CRC). The aim of our study was to evaluate the pathological and molecular features of specific KRAS mutated colorectal carcinomas. KRAS and BRAF (V600E) mutation tests were performed in 762 primary tumors from a consecutive cohort study of Chinese CRC patients.

METHODS

DNA mismatch repair (MMR) status was determined by immunohistochemistry (IHC) staining. Assessment of KRAS and BRAF V600E mutational status was performed using a multiplex allele-specific PCR-based assay.

RESULTS

Mutations of KRAS (34.8%) and BRAF (V600E) (3.1%) were nearly mutually exclusive. Both KRAS- and BRAF- mutated tumors were more likely to be located at proximal colon than wild-type (WT) carcinomas. KRAS-mutated carcinomas were more frequently observed in female patients (47.5% vs 37.1%, p = 0.005) and mucinous differentiation (34.7% vs 24.8%, p = 0.004), but have no difference between lymph node (LN) metastases and among pTNM stages. Whereas, BRAF-mutated carcinomas more frequently demonstrated histologic features such as proximal location (60.9% vs 20.9%, p = 0.001), low-grade histology (43.5% vs 18.0%, p = 0.005), mucinous differentiation (69.6% vs 25.9%, p = 0.001) and deficient MMR (dMMR) (21.7% vs 7.6%, p = 0.03). In particular, KRAS codon 12 mutated carcinomas had increased lymph node metastasis (odds ratio [OR] = 1.31; 95% confidence interval [CI] = 1.04 to 1.65; P = 0.02) and were more likely in higher disease stage (III-IV) than that of WT carcinomas (OR = 1.30; 95% CI = 1.03 to 1.64; P = 0.03). However, there were no significant differences in lymph node metastasis and disease stage between KRAS codon 13 mutated carcinoma and WT carcinoma patients.

CONCLUSIONS

In summary, KRAS codon 12 mutation, but not codon 13 mutation, is associated with lymph node metastasis and higher tumor stages.

Somatic c.34G>T KRAS mutation: a new prescreening test for MUTYH-associated polyposis?

We investigated the somatic c.34G>T KRAS transversion as a marker suggestive of MUTYH-associated polyposis (MAP). We compared 86 adenomas and 19 colorectal cancers (CRCs) of 30 MAP patients to 135 adenomas and five CRCs of 47 familial adenomatous polyposis (FAP) patients. The c.34G>T mutation was investigated by DNA sequencing. Secondly, the germline MUTYH gene sequence was analyzed in patients carrying c.34G>T in CRCs diagnosed between 2008 and 2012. The c.34G>T was present in 39.7% of MAP adenomas versus 1.6% of FAP adenomas (P < 0.01). Sensitivity and specificity for detecting MAP were 39.7% and 98%, respectively. Sensitivity increased with the number of adenomas tested (P = 0.039). KRAS exon 2 analysis was performed on 2239 CRC and 2.2% harbored the c.34G>T transversion. Among 28 carriers of the c.34G>T mutation, biallelic MUTYH mutations were detected in seven patients (25%). One patient did not have any polyp or family history and did not fulfill criteria for MUTYH testing. With high specificity, the c.34G>T mutation seems to be a useful and promising test for MAP. For polyposis, it may guide genetic testing toward APC or MUTYH. If routinely performed in CRC patients, it could help to diagnose MUTYH-mutation carriers, even when they don't fulfill genetic testing criteria.

KRAS mutation screening by chip-based DNA hybridization--a further step towards personalized oncology

The use of predictive biomarkers can help to improve therapeutic options for the individual cancer patient. For the treatment of colon cancer patients with anti-EGFR-based drugs, the KRAS mutation status has to be determined to pre-select responders that will benefit from this medication. Amongst others, array-based tests have been established for profiling of the KRAS mutation status. Within this article we describe an on-chip hybridization technique to screen therapeutic relevant KRAS codon 12 mutations. The DNA chip-based platform enables the reliable discrimination of selected mutations by allele-specific hybridization. Here, silver deposits represent robust endpoint signals that allow for a simple naked eye rating. With the here presented assay concept a precise identification of heterozygous and homozygous KRAS mutations, even against a background of up to 95% wild-type DNA, was realizable. The applicability of the test was successfully proven for various cancer cell lines as well as clinical tumour samples. Thus, the chip-based DNA hybridization technique seems to be a promising tool for KRAS mutation analysis to further improve personalized cancer treatment.

The immune microenvironment of the colorectal tumor: Involvement of immunity genes and microRNAs belonging to the TH17 pathway

Colorectal cancer is a complex and multifactorial disease. Various factors such as genetic, immunological, epigenetic and environmental constitute minor risk factors with their additive effects contributing to the advent of colorectal cancer. In order to evaluate the role of innate and adaptive immunity in the susceptibility, the presentation and the development of colorectal cancer, we considered an immunogenetic approach on polymorphisms in the TLR4 gene and NOD2/CARD15 gene (receptors of innate immunity) as well as in cytokine genes of the TH17 pathway IL17A, IL17F and cytokine receptor IL23R. Then, we evaluated the expression of microRNAs regulated by TLR4 and NOD2/CARD15 or targeting TLR4, IL17 and proinflammatory cytokines (IL-6, TNF) induced by IL17. Through a case-control study, we showed that the polymorphism of IL17A is associated with its susceptibility to colorectal cancer. Considering the tumor location, we found that the mutated alleles of IL17A, IL17F and IL23R are rather associated with colon cancer and not with rectum cancer. This result confirms that the colon and rectum are two different physiological entities. This study shows that TLR4, IL17A/F and IL23R polymorphisms are involved in the presentation of the disease with regard to tumor architecture, histology, and differentiation, advanced stage of the disease and lymph node and metastasis. Overall, these polymorphisms are associated with a poor prognosis of the disease. Furthermore, in order to evaluate the involvement of epigenetic mechanisms in the occurrence of colorectal cancer, we aimed at analyzing the tumor compared to a normal adjacent tissue and the expression of miRNAs (miR21, miR146a, miR135a, miR147b and miR155) that regulate immunity genes especially the cytokines of the TH17 pathway. This research has shown that microRNAs 21, 135a and 146a are associated with colorectal cancer. Indeed, these three miRs are overexpressed in cancer tissue compared to healthy tissue. These results clearly confirm the involvement of epigenetics in colorectal cancer. In other words, this study reveals the importance of immunity and specifically the TH17 pathway in the development and presentation of colorectal cancer. These results suggest that TLR4, IL17A, IL17F and IL23R polymorphisms as well as the expression of microRNAs that regulate inflammation and the TH17 pathway are associated with the evolution and progression of the colorectal tumor that could be considered as biomarkers in colorectal cancer.

KRAS gene mutation in a series of unselected colorectal carcinoma patients with prognostic morphological correlations: a pyrosequencing method improved by nested PCR

INTRODUCTION

Inhibition of EGFR is a strategy for treating metastatic colorectal cancer (CRC) patients. KRAS sequencing is mandatory for selecting wild-type tumor patients who might benefit from this treatment. DNA from formalin-fixed paraffin-embedded (FFPE) tissues is commonly used for routine clinical detection of mutations, and its amplification succeeds only when all preanalytical histological processes have been controlled. In cases that are not properly processed, the DNA results can be poor, with low peak pyrosequencing findings. We designed and tested a pair of forward and reverse primers for a nested PCR method, followed by pyrosequencing, in a single Latin American institution series of 422 unselected CRC patients, correlating KRAS mutations with pathological and clinical data.

MATERIALS AND METHODS

Patient DNA samples from tumors were obtained by scraping or laser microdissection of cells from FFPE tissue and extracted using a commercial kit. DNA was first amplified by PCR using 2 primers that we designed; then, nested PCR was performed with the amplicon from the preamplification PCR using the KRAS PyroMark™ Q96 V2.0 kit (Qiagen). Pathological data were retrieved from pathology reports.

RESULTS

KRAS mutation was observed in 33% of 421 cases. Codon 12 was mutated in 76% of cases versus codon 13 in 24%. Right-sided CRCs harbored more KRAS mutations than left-sided tumors, as did tumors that presented with perineural invasion.

CONCLUSION

Our findings in this Latin American population are consistent with the literature regarding the frequency of KRAS mutations in CRC, their distribution between codons 12 and 13, and type of nucleotide substitution. By combining nested PCR and pyrosequencing, we achieved a high rate of conclusive results in testing KRAS mutations in CRC samples - a method that can be used as an ancillary test for failed assays by conventional PCR.

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

PURPOSE

The 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 DESIGN

A 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.

RESULTS

Of 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%).

CONCLUSIONS

KRAS 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.

Microsatellite instability and mutations in BRAF and KRAS are significant predictors of disseminated disease in colon cancer

BACKGROUND

Molecular alterations are well studied in colon cancer, however there is still need for an improved understanding of their prognostic impact. This study aims to characterize colon cancer with regard to KRAS, BRAF, and PIK3CA mutations, microsatellite instability (MSI), and average DNA copy number, in connection with tumour dissemination and recurrence in patients with colon cancer.

METHODS

Disease stage II-IV colon cancer patients (n = 121) were selected. KRAS, BRAF, and PIK3CA mutation status was assessed by pyrosequencing and MSI was determined by analysis of mononucleotide repeat markers. Genome-wide average DNA copy number and allelic imbalance was evaluated by SNP array analysis.

RESULTS

Patients with mutated KRAS were more likely to experience disease dissemination (OR 2.75; 95% CI 1.28-6.04), whereas the opposite was observed for patients with BRAF mutation (OR 0.34; 95% 0.14-0.81) or MSI (OR 0.24; 95% 0.09-0.64). Also in the subset of patients with stage II-III disease, both MSI (OR 0.29; 95% 0.10-0.86) and BRAF mutation (OR 0.32; 95% 0.16-0.91) were related to lower risk of distant recurrence. However, average DNA copy number and PIK3CA mutations were not associated with disease dissemination.

CONCLUSIONS

The present study revealed that tumour dissemination is less likely to occur in colon cancer patients with MSI and BRAF mutation, whereas the presence of a KRAS mutation increases the likelihood of disseminated disease.

Role of KRAS mutation as predictor of pathologic response after neoadjuvant chemoradiation therapy for rectal cancer

Individual patient response to neoadjuvant treatment is variable and reproducible biomarkers of response are needed. The role of the V-Ki-ras2 Kirsten rat sarcoma viral oncogene (KRAS) in rectal cancer remains equivocal. The aim of the current study was to evaluate the effect of KRAS mutation on outcomes following neoadjuvant chemoradiation therapy (CRT) for rectal cancer. A total of 76 stage II-III rectal cancer patients underwent preoperative CRT followed by surgery. In every patient tumor-related features and outcome results were considered for analysis and correlation with KRAS mutations. Forty-four patients (58%) obtained a downstaging after CRT, and in 7 patients (9%) a complete pathological response was found. Twenty-six (33%) mutations of KRAS were found in 26 patients. Nineteen mutations (73%) were located in codon 12, 6 in codon 13(23%) and 1 in codon 61. T-level downsizing and tumor downstaging showed no significant association with KRAS mutation status, except for mutation of codon 13(G13D). No correlation between cancer-associated mortality following CRT and surgery and KRAS mutation was observed. No correlation between pelvic recurrence and KRAS mutation was observed. KRAS mutation also failed to correlate with disease-free survival. No patients with a pCR had a local or distant failure. There appears to be no significant difference in pCR, tumor down-staging, T-downsizing or effects on cancer-associated mortality, overall survival and disease-free survival in patients with KRAS mutations except for patients with KRAS codon 13 mutations that seem to be resistant to neoadjuvant CRT and less likely to achieve a pCR.

Dual phosphoinositide 3-kinase/mammalian target of rapamycin inhibitor is an effective radiosensitizer for colorectal cancer

The present study was aimed to investigate whether combination of molecular targeting therapy, a dual PI3K/mTOR inhibitor (BEZ235), with radiation can enhance the radiosensitivity of colorectal cancer cells (CRC). K-RAS mutant CRC cells (HCT 116 and SW 620) and wild type CRC cells (HT 29) were irradiated with different dose of radiation (0-6 Gy). The synergistic effects of combining radiation with different concentration of BEZ235 (0-10 nM) pretreatment were demonstrated by cell survival assay. When comparing with radiation alone and BEZ235 alone, the combination of BEZ235 pretreatment and radiation resulted in an increased percentage of sub-G1 phase cells, and an increased number of γ-H2AX/cell (DNA double strand breaks). Radiation up-regulated AKT/mTOR signaling pathway, including the activation of phospho (p)-AKT, p-mTOR, p-eIF4E, and p-rpS6; and this activated AKT/mTOR signaling pathway was attenuated by BEZ235 pretreatment. In addition, BEZ235 blocked double strand break repair induced by radiation through attenuating the activation of ATM and DNA-PKcs and sensitized CRC cells to radiation. In vivo model, the tumor size and the expression pattern of p-mTOR, p-eIF4E, and p-rpS6 were significantly decreased in combined group than radiation alone or BEZ235 alone. Our findings indicate that the administration of BEZ235 before radiation enhances the radiotherapeutic effect of CRC cells both in vitro and in vivo.

High MACC1 expression in combination with mutated KRAS G13 indicates poor survival of colorectal cancer patients

Background

The metastasis-associated in colon cancer 1 (MACC1) gene has been identified as prognostic biomarker for colorectal cancer (CRC). Here, we aimed at the refinement of risk assessment by separate and combined survival analyses of MACC1 expression with any of the markers KRAS mutated in codon 12 (KRAS G12) or codon 13 (KRAS G13), BRAF V600 mutation and MSI status in a retrospective study of 99 CRC patients with tumors UICC staged I, II and III.

Findings

We showed that only high MACC1 expression (HR: 6.09, 95% CI: 2.50-14.85, P < 0.001) and KRAS G13 mutation (HR: 5.19, 95% CI: 1.06-25.45, P = 0.042) were independent prognostic markers for shorter metastasis-free survival (MFS). Accordingly, Cox regression analysis revealed that patients with high MACC1 expression and KRAS G13 mutation exhibited the worst prognosis (HR: 14.48, 95% CI: 3.37-62.18, P < 0.001). Patients were classified based on their molecular characteristics into four clusters with significant differences in MFS (P = 0.003) by using the SPSS 2-step cluster function and Kaplan-Meier survival analysis.

Conclusion

According to our results, patients with high MACC1 expression and mutated KRAS G13 exhibited the highest risk for metachronous metastases formation. Moreover, we demonstrated that the “Traditional pathway” with an intermediate risk for metastasis formation can be further subdivided by assessing MACC1 expression into a low and high risk group with regard to MFS prognosis. This is the first report showing that identification of CRC patients at high risk for metastasis is possible by assessing MACC1 expression in combination with KRAS G13 mutation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0316-2) contains supplementary material, which is available to authorized users.

PIK3CA mutations predict recurrence in localized microsatellite stable colon cancer

PIK3CA, which encodes the p110α catalytic subunit of PI3Kα, is one of the most frequently altered oncogenes in colon cancer (CC), but its prognostic value is still a matter of debate. Few reports have addressed the association between PIK3CA mutations and survival and their results are controversial. In the present study, we aimed to clarify the prognostic impact of PIK3CA mutations in stage I-III CC according to mismatch repair status. Fresh frozen tissue samples from two independent cohorts with a total of 826 patients who underwent curative surgical resection of CC were analyzed for microsatellite instability and screened for activating point mutations in exon 9 and 20 of PIK3CA by direct sequencing. Overall, 693 tumors (84%) exhibited microsatellite stability (MSS) and 113 samples (14%) harbored PIK3CA mutation. In the retrospective training cohort (n = 433), patients with PIK3CA-mutated MSS tumors (n = 47) experienced a significant increased 5-year relapse-free interval compared with PIK3CA wild-type MSS tumors (n = 319) in univariate analysis (94% vs. 68%, Log-rank P = 0. 0003) and in multivariate analysis (HR = 0.12; 95% confidence interval, 0.029-0.48; P = 0.0027). In the prospective validation cohort (n = 393), the favorable prognostic impact of PIK3CA mutations in MSS tumors (n = 327) was confirmed (83% vs. 67%, Log-rank P = 0.04). Our study showed that PIK3CA mutations are associated with a good prognosis in patients with MSS stage I-III CC.