Impact of KRAS and BRAF Gene Mutation Status on Outcomes From the Phase III AGITG MAX Trial of Capecitabine Alone or in Combination With Bevacizumab and Mitomycin in Advanced Colorectal Cancer

Adjuvant systemic chemotherapy with or without bevacizumab in patients with resected pulmonary metastases from colorectal cancer

INTRODUCTION

We investigated the impact of modern chemotherapy regimens and bevacizumab following pulmonary metastasectomy (PM) from metastatic colorectal cancer (CRC).

METHODS

A total of 122 consecutive patients who were curatively resected for pulmonary metastases of CRC in twelve oncology centers were retrospectively analysed between January 2000 and April 2012.

RESULTS

Of 122 patients, 14 did not receive any treatment following PM. The remaining 108 patients received fluoropyrimidine-based (n = 12), irinotecan-based (n = 56) and oxaliplatin-based (n = 40) chemotherapy combinations. Among these, 52 patients received bevacizumab (BEV) while 56 did not (NoBEV). Median recurrence-free survival (RFS) was 17 months and median overall survival (OS) has not been reached at a median follow-up of 25 months after PM. Three and five-year OS rates were 66% and 53%, respectively. RFS and OS were similar, irrespective of the chemotherapy regimen or BEV use. Positive pulmonary margin, KRAS mutation status, and previous liver metastasectomy were negative independent prognostic factors for RFS, while pathologically confirmed thoracic lymph node involvement was the only negative independent prognostic for OS in multivariate analysis.

CONCLUSIONS

No significant RFS or OS difference was observed in respect to chemotherapy regimens with or without BEV in patients with pulmonary metastases of CRC following curative resection.

Mismatch repair status and BRAF mutation status in metastatic colorectal cancer patients: a pooled analysis of the CAIRO, CAIRO2, COIN, and FOCUS studies

PURPOSE

To determine the prevalence and prognostic value of mismatch repair (MMR) status and its relation to BRAF mutation (BRAF(MT)) status in metastatic colorectal cancer (mCRC).

EXPERIMENTAL DESIGN

A pooled analysis of four phase III studies in first-line treatment of mCRC (CAIRO, CAIRO2, COIN, and FOCUS) was performed. Primary outcome parameter was the hazard ratio (HR) for median progression-free survival (PFS) and overall survival (OS) in relation to MMR and BRAF. For the pooled analysis, Cox regression analysis was performed on individual patient data.

RESULTS

The primary tumors of 3,063 patients were analyzed, of which 153 (5.0%) exhibited deficient MMR (dMMR) and 250 (8.2%) a BRAF(MT). BRAF(MT) was observed in 53 (34.6%) of patients with dMMR tumors compared with 197 (6.8%) of patients with proficient MMR (pMMR) tumors (P < 0.001). In the pooled dataset, median PFS and OS were significantly worse for patients with dMMR compared with pMMR tumors [HR, 1.33; 95% confidence interval (CI), 1.12-1.57 and HR, 1.35; 95% CI, 1.13-1.61, respectively), and for patients with BRAF(MT) compared with BRAF wild-type (BRAF(WT)) tumors (HR, 1.34; 95% CI, 1.17-1.54 and HR, 1.91; 95% CI, 1.66-2.19, respectively). PFS and OS were significantly decreased for patients with BRAF(MT) within the group of patients with pMMR, but not for BRAF status within dMMR, or MMR status within BRAF(WT) or BRAF(MT).

CONCLUSIONS

Prevalence of dMMR and BRAF(MT) in patients with mCRC is low and both biomarkers confer an inferior prognosis. Our data suggest that the poor prognosis of dMMR is driven by the BRAF(MT) status.

A very low incidence of BRAF mutations in Middle Eastern colorectal carcinoma

Background

Recent studies emphasize the role of BRAF as a genetic marker for prediction, prognosis and risk stratification in colorectal cancer. Earlier studies have reported the incidence of BRAF mutations in the range of 5-20% in colorectal carcinomas (CRC) and are predominantly seen in the serrated adenoma-carcinoma pathway characterized by microsatellite instability (MSI-H) and hypermethylation of the MLH1 gene in the setting of the CpG island methylator phenotype (CIMP). Due to the lack of data on the true incidence of BRAF mutations in Saudi Arabia, we sought to analyze the incidence of BRAF mutations in this ethnic group.

Methods

770 CRC cases were analyzed for BRAF and KRAS mutations by direct DNA sequencing.

Results

BRAF gene mutations were seen in 2.5% (19/757) CRC analyzed and BRAF V600E somatic mutation constituted 90% (17/19) of all BRAF mutations. BRAF mutations were significantly associated with right sided tumors (p = 0.0019), MSI-H status (p = 0.0144), CIMP (p = 0.0017) and a high proliferative index of Ki67 expression (p = 0.0162). Incidence of KRAS mutations was 28.6% (216/755) and a mutual exclusivity was noted with BRAF mutations (p = 0.0518; a trend was seen).

Conclusion

Our results highlight the low incidence of BRAF mutations and CIMP in CRC from Saudi Arabia. This could be attributed to ethnic differences and warrant further investigation to elucidate the effect of other environmental and genetic factors. These findings indirectly suggest the possibility of a higher incidence of familial hereditary colorectal cancers especially Hereditary non polyposis colorectal cancer (HNPCC) syndrome /Lynch Syndrome (LS) in Saudi Arabia.

Progression-free survival remains poor over sequential lines of systemic therapy in patients with BRAF-mutated colorectal cancer

BACKGROUND

BRAF mutations occur in 5% to 10% of metastatic colorectal cancers and are biomarkers associated with a poor prognosis. However, the outcomes with standard chemotherapy over sequential lines of therapy in a large cohort of patients with BRAF-mutant tumors have not been described.

PATIENTS AND METHODS

We searched the M.D. Anderson Cancer Center databases for patients with colorectal cancer and identified BRAF mutations between December 2003 and May 2012. Patients were analyzed for clinical characteristics, PFS, overall survival, and chemotherapeutic agents used. Survival was estimated according to the Kaplan-Meier method.

RESULTS

Among the 1567 patients tested for BRAF mutations at our institution, 127 (8.1%) had tumors with BRAF mutations. The 71 patients who presented with metastatic disease received a median of 2 lines of chemotherapy. For the first 3 lines of chemotherapy, median PFS was 6.3 months (n = 69 patients; 95% confidence interval [CI], 4.9-7.7 months), 2.5 months (n = 58 patients; 95% CI, 1.8-3.0 months), and 2.6 months (n = 31 patients; 95% CI, 1.0-4.2 months), respectively. Median PFS was not affected by the backbone chemotherapeutic agent in the first-line setting, whether oxaliplatin-based or irinotecan-based (6.4 months vs. 5.4 months, respectively; P = .99).

CONCLUSION

PFS is expectedly poor for patients with BRAF-mutated metastatic colorectal cancer. Despite the ascertainment bias present (with testing preferentially performed in patients suitable for clinical trials in refractory disease), these data provide historic controls suitable for future study design and support the idea that novel therapeutic options are essential in this population.

Prognostic significance of AMPK activation in advanced stage colorectal cancer treated with chemotherapy plus bevacizumab

Background:

AMP-activated protein kinase (AMPK) has a central role in cellular energy sensing and is activated in preclinical tumour models following anti-vascular endothelial growth factor (VEGF) therapy. The possible predictive or prognostic role of AMPK status in cancer patients treated with anti-VEGF drugs has not been investigated so far.

Methods:

Expression of components of the AMPK pathway including phosphorylated AMPK (pAMPK), phosphorylated acetyl-Coa carboxylase (pACC) and liver kinase B1 (LKB1) was investigated by immunohistochemistry in 48 colorectal cancers treated with FOLFIRI plus bevacizumab. Correlation between pAMPK and pACC and associations between the AMPK pathway scores and clinico-pathological characteristics were assessed. Overall survival (OS) was estimated through Kaplan–Meier method, whereas hazard ratios were computed to identify prognostic factors.

Results:

Fourteen patients (29.2%) were included in the pAMPK-negative group (score ⩽5), whereas 34 patients (70.8%) were included in the pAMPK-positive group (score >5). The Spearman's coefficient for the correlation between pAMPK and pACC scores in primary tumour samples was 0.514 (P=0.0002). Low pAMPK levels were associated with worse OS (P-value 0.0002) but not with PFS, whereas low pACC levels were associated both with worse OS and PFS (P-value 0.0007 and 0.01, respectively).

Conclusions:

Our findings suggest that high tissue AMPK activation is a prognostic biomarker in this cohort of metastatic colorectal cancer patients.

The role of antiangiogenic agents in the treatment of patients with advanced colorectal cancer according to K-RAS status

Colorectal cancer (CRC) is the fourth most commonly diagnosed cancer worldwide. Recently, it has been found that about 40 % of patients with CRC have mutations in the K-RAS gene. Several clinical trials have showed that patients with metastatic colorectal cancer (mCRC) who present tumour-promoting mutations in signalling pathways involving the epidermal growth factor receptor (EGFR), which includes activating K-RAS mutations, do not respond to anti-EGFR drugs such as panitumumab and cetuximab. Hence, K-RAS status is now considered an important negative predictive factor for response to anti-EGFR drugs. Moreover, K-RAS status seems to have also a prognostic role in CRC, but this fact is somewhat controversial. Activity of antiangiogenic agents seems not to be influenced by K-RAS gene status. Tumour angiogenesis has attracted interest in attempts to improve the management of mCRC. The vascular endothelial growth factor (VEGF) pathway is fundamental to the regulation of angiogenesis, and research has focused on developing agents that selectively target it. In this way, the anti-VEGF antibody bevacizumab in combination with chemotherapy has provided important clinical benefits in terms of response rate, progression-free survival and overall survival to patients with mCRC. Efficacy data of bevacizumab in K-RAS wild-type patients seem to be comparable with the efficacy data observed with anti-EGFR therapies in a cross-trial comparison. Although there is a lack of prospective and randomized data in this setting, the combination of chemotherapy plus antiangiogenic agents could be considered as an effective alternative for the treatment of mCRC with independence of K-RAS gene status. Here, we review the available data we have in the literature of the use of antiangiogenic strategies in the treatment of mCRC nowadays.

Predictive and prognostic biomarkers with therapeutic targets in advanced colorectal cancer

Colorectal cancer (CRC) is one of the most common human malignant diseases and the second leading cause of cancer-related deaths worldwide. The treatment of advanced CRC has improved significantly in recent years. With the emergence of two targeted antibodies, cetuximab (Erbitux), an anti-epidermal growth factor receptor monoclonal antibody and bevacizumab (Avastin), a vascular endothelial growth factor monoclonal antibody, the treatment of metastatic CRC has entered the era of personalized therapy. Predictive and prognostic biomarkers have, and will continue to, facilitate the selection of suitable patients and the personalization of treatment for metastatic CRC (mCRC). In this review, we will focus primarily on the important progresses made in the personalized treatment of mCRC and discuss the potentially novel predictive and prognostic biomarkers for improved selection of patients for anti-cancer treatment in the future.

Predictive biomarkers of response to anti-EGF receptor monoclonal antibody therapies

SUMMARY 

The EGF receptor (EGFR) pathway plays an important role in the progression of several carcinomas, including colorectal cancer (CRC). The EGFR has emerged as a candidate for targeted therapy for CRC. Two monoclonal antibodies used to inhibit the EGFR signaling pathway are cetuximab and panitumumab. Both these monoclonal antibodies inhibit tumor-promoting activities, such as tumor cell proliferation, survival, angiogenesis and metastasis. However, only a subpopulation of metastatic CRC patients responds to such therapy. Constitutive activation within the pathway gives rise to other aberrantly expressed biomarkers that are able to circumvent the anti-EGFR treatment and confer resistance. Mechanisms of resistance and the value of these emerging predictive biomarkers in the clinical setting are discussed in this review.

KRAS codon 12 and 13 mutations in relation to disease-free survival in BRAF-wild-type stage III colon cancers from an adjuvant chemotherapy trial (N0147 alliance)

PURPOSE

We examined the prognostic impact of specific KRAS mutations in patients with stage III colon adenocarcinoma receiving adjuvant FOLFOX alone or combined with cetuximab in a phase III trial (N0147). Analysis was restricted to BRAF-wild-type tumors, because BRAF mutation was associated with poor prognosis, and BRAF and KRAS mutations are mutually exclusive.

EXPERIMENTAL DESIGN

The seven most common KRAS mutations in codon 12 and codon 13 were examined in 2,478 BRAF-wild-type tumors. Because KRAS mutations in codon 12 (n = 779) or 13 (n = 220) were not predictive of adjuvant cetuximab benefit, study arms were pooled for analysis. Disease-free survival (DFS) was evaluated by HRs using Cox models.

RESULTS

KRAS mutations in codon 12 (multivariate HR, 1.52; 95% confidence interval, CI, 1.28-1.80; P < 0.0001) or codon 13 (multivariate HR, 1.36; 95% CI, 1.04-1.77; P = 0.0248) were significantly associated with shorter DFS compared with patients with wild-type KRAS/BRAF tumors, independent of covariates. KRAS codon 12 mutations were independently associated with proficient mismatch repair (P < 0.0001), proximal tumor site (P < 0.0001), low grade, age, and sex, whereas codon 13 mutations were associated with proximal site (P < 0.0001).

CONCLUSION

KRAS mutations in either codon 12 or 13 are associated with inferior survival in patients with resected stage III colon cancer. These data highlight the importance of accurate molecular characterization and the significant role of KRAS mutations in both codons in the progression of this malignancy in the adjuvant setting. Clin Cancer Res; 20(11); 3033-43. ©2014 AACR.

BRAFV600E mutation and its association with clinicopathological features of colorectal cancer: a systematic review and meta-analysis

Background

Colorectal cancer (CRC) is a heterogeneous disease with multiple underlying causative genetic mutations. The B-type Raf proto-oncogene (BRAF) plays an important role in the mitogen-activated protein kinase (MAPK) signaling cascade during CRC. The presence of BRAF^V600E mutation can determine the response of a tumor to chemotherapy. However, the association between the BRAF^V600E mutation and the clinicopathological features of CRC remains controversial. We performed a systematic review and meta-analysis to estimate the effect of BRAF^V600E mutation on the clinicopathological characteristics of CRC.

Methods

We identified studies that examined the effect of BRAF^V600E mutation on CRC within the PubMed, ISI Science Citation Index, and Embase databases. The effect of BRAF^V600E on outcome parameters was estimated by odds ratios (ORs) with 95% confidence intervals (CIs) for each study using a fixed effects or random effects model.

Results

25 studies with a total of 11,955 CRC patients met inclusion criteria. The rate of BRAF^V600 was 10.8% (1288/11955). The BRAF^V600E mutation in CRC was associated with advanced TNM stage, poor differentiation, mucinous histology, microsatellite instability (MSI), CpG island methylator phenotype (CIMP). This mutation was also associated with female gender, older age, proximal colon, and mutL homolog 1 (MLH1) methylation.

Conclusions

This meta-analysis demonstrated that BRAF^V600E mutation was significantly correlated with adverse pathological features of CRC and distinct clinical characteristics. These data suggest that BRAF^V600E mutation could be used to supplement standard clinical and pathological staging for the better management of individual CRC patients, and could be considered as a poor prognostic marker for CRC.

Association of VEGF-A splice variant mRNA expression with outcome in bevacizumab-treated patients with metastatic breast cancer

BACKGROUND

The prognostic utility of vascular endothelial growth factor A (VEGF-A) splice variants in patients with advanced breast cancer treated with bevacizumab has not been studied.

PATIENTS AND METHODS

A total of 111 patients with metastatic breast cancer treated with weekly docetaxel or ixabepilone without bevacizumab (cohort A) and 100 treated with weekly paclitaxel and bevacizumab (cohort B) were studied. Formalin-fixed tumors were macrodissected for reverse transcription quantitative polymerase chain reaction relative quantification of VEGF-A165, -189, and -206 isoforms spliced at exon 8 proximal splice site (VEGF-Axxxa) and at exon 8 distal splice site (VEGF-Axxxb).

RESULTS

For high VEGF-Axxxa, the hazard ratios (HRs) for progression were 1.08 (P = .71) in non-bevacizumab-treated patients (cohort A) and 0.66 (P = .22) in bevacizumab-treated patients (cohort B), and the HRs for death were 1.45 (P = .13) and 0.50 (P = .049), respectively. The interaction of VEGF-Axxxa with bevacizumab administration was significant (P = .011) for overall survival (OS). High tissue VEGF-Axxxb was not prognostic in cohort A but was predictive for bevacizumab benefit in cohort B (HR for progression, 0.57 [P = .04]; HR for death, 0.51 [P = .02]). Exploratory analyses done only in cohort B suggested that abundance of VEGFR1 messenger RNA (mRNA) in peripheral blood and low VEGFR2 mRNA in tissue correlated with poor outcome. In multivariate analysis, high tissue mRNA of angiogenic VEGF-Axxxa in the presence of bevacizumab therapy predicted for favorable progression-free survival (HR for progression, 0.39; P = .0227) and OS (HR for death, 0.32; P = .0140).

CONCLUSION

Tissue mRNA expression of angiogenic VEGF-Axxxa isoforms was retrospectively associated with adverse prognosis in the absence of bevacizumab and with favorable outcome when bevacizumab was administered in patients with advanced breast cancer.

How to select the optimal treatment for first line metastatic colorectal cancer

Choice of first line treatment for patients with metastatic colorectal cancer (mCRC) is based on tumour and patient related factors and molecular information for determination of individual treatment aim and thus treatment intensity. Recent advances (e.g., extended RAS testing) enable tailored patient assignment to the most beneficial treatment approach. Besides fluoropyrimidines, irinotecan and oxaliplatin, a broad variety of molecular targeting agents are currently available, e.g., anti-angiogenic agents (bevacizumab) and epidermal growth factor receptor (EGFR) antibodies (cetuximab, panitumumab) for first line treatment of mCRC. Although some combinations should be avoided (e.g., oral or bolus fluoropyrimidines, oxaliplatin and EGFR antibodies), treatment options range from single agent to highly effective four-drug regimen. Preliminary data comparing EGFR antibodies and bevacizumab, both with chemotherapy, seem to favour EGFR antibodies in RAS wildtype disease. However, choosing the most appropriate treatment approach for mCRC patients remains a complex issue, with numerous open questions.

Proangiogenic tumor proteins as potential predictive or prognostic biomarkers for bevacizumab therapy in metastatic colorectal cancer

Tumor biomarkers to more accurately predict a patient's response to a given therapy are much needed in oncology practice. For metastatic colorectal cancer the anti-vascular endothelial growth factor (VEGF) monoclonal antibody bevacizumab is now commonly included in first-line therapy regimens and has led to modest but significant improvements in patient outcomes compared with chemotherapy. Given the modest gains there is a pressing need for predictive biomarkers to better identify patients who would benefit from this targeted therapy. We used a multiplex protein assay to determine the tumor expression levels of the proangiogenic proteins IL-6, IL-8, bFGF, PDGF-BB and VEGF-A in formalin-fixed paraffin-embedded tumors from the MAX clinical trial patients with available tissue samples. Patients were dichotomized into "low" vs. "high" expression subgroups based on median baseline levels to correlate with objective response rate (ORR), progression-free survival (PFS) and overall survival (OS). "Low" tumor VEGF-A level was predictive of better ORR for bevacizumab [ORR (low) 53% vs. (high) 19%, interaction p = 0.03] but not for PFS [hazard ratio, HR (low) 0.73 vs. (high) 0.62, interaction p = 0.68] in the comparison of capecitabine (C) versus C and bevacizumab (CB) and CB plus mitomycin (M). When analyzed as a dichotomized variable, "high" VEGF-A was prognostic for shorter PFS (unadjusted HR 1.34, p = 0.06; adjusted HR 1.55, p = 0.008). The other four proteins were neither predictive of bevacizumab benefits nor prognostic for ORR, PFS or OS. "Low" tumor VEGF-A was associated with longer PFS after adjustment for other baseline factors. Proangiogenic proteins were not predictive of benefit with bevacizumab for PFS.

Dose KRAS Mutation Status Affect on the Effect of VEGF Therapy in Metastatic Colon Cancer Patients?

Purpose

Mutations affecting the KRAS gene are an established negative predictor for anti-epidermal growth factor receptor (anti-EGFR) therapies in metastatic colorectal cancer (CRC). However, the role of KRAS mutation as a biomarker for anti-vascular endothelial growth factor (VEGF) remains controversial.

Materials and Methods

We analyzed retrospective data from 32 CRC patients who were available for KRAS mutation status and received cytotoxic chemotherapy plus bevacizumab as a first-line therapy. Six of 32 patients received anti-EGFR therapies. We used KRAS mutation status as a predictive or prognostic factor in CRC patients receiving bevacizumab.

Results

We observed mutations in KRAS in 59.4% of patients. Bevacizumab was used in combination with oxaliplatin based regimens. There was no significant difference for progression free survival (PFS) and overall survival (OS) in patients with oxaliplatin based cytotoxic chemotherapy plus bevacizumab according to the status of KRAS mutation. After first-line therapy, 28 patients (87.5%) received second-line therapy. In univariate analysis, KRAS mutations did not have a major prognostic value for PFS (hazard ratio, 1.007; 95% confidence interval [CI], 0.469 to 2.162; p>0.05) or OS (hazard ratio, 0.548; 95% CI, 0.226 to 1.328; p>0.05). In addition, anti-EGFR therapies did not affect the impact on OS.

Conclusion

KRAS mutation is neither a predictive for bevacizumab nor a prognostic for OS in CRC patients receiving anti-VEGF therapy.

Personalizing therapy for colorectal cancer

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide. Several important scientific discoveries in the molecular biology of CRC have changed clinical practice in oncology. These included the comprehensive genome-wide profiling of CRC by the Cancer Genome Atlas Network, the discovery of mutations along the RAS-RAF signaling pathway as major determinants of response to antibodies against the epidermal growth factor receptor, the elucidation of new molecular subsets of CRC or gene signatures that may predict clinical outcome after adjuvant chemotherapy, and the innovative targeting of the family of vascular endothelial growth factor and receptors. These new data have allowed oncologists to individualize drug therapy on the basis of a patient's tumor's unique molecular profile, especially in the management of metastatic CRC. This review article will discuss the progress of personalized medicine in the contemporary management of CRC.

Panitumumab in the management of patients with KRAS wild-type metastatic colorectal cancer

The past 15 years has seen a marked increase in available therapeutic options for patients with metastatic colorectal cancer resulting in improvements in median survival from 12 to 24 months. One of these new options is panitumumab, which is a fully humanized monoclonal antibody that binds to the epidermal growth factor receptor of tumor cells and inhibits downstream cell signaling with antitumor effects of inhibition of tumor growth, induction of apoptosis and inhibition of angiogenesis. Large randomized clinical trials have demonstrated significant improvements in tumor response rates and progression-free survival when panitumumab is combined with chemotherapy and as monotherapy in chemorefractory metastatic colorectal cancer. Clinical benefit with panitumumab is limited to patients with nonmutated KRAS tumors. Rash is a common toxicity of panitumumab treatment but can potentially be ameliorated with the use of prophylactic strategies. The role of panitumumab in the overall treatment of metastatic colorectal cancer is evolving and future clinical trials will focus on improved patient selection through use of novel predictive biomarkers, and the optimal timing of treatment.

Retrospective analysis of pathological response in colorectal cancer liver metastases following treatment with bevacizumab

AIMS

Pathological response has been shown to be a predictor for survival after preoperative chemotherapy and surgical resection of colorectal cancer liver metastases. This retrospective analysis evaluated the effect on pathological response of adding bevacizumab to standard neoadjuvant chemotherapy in patients with metastatic colorectal cancer (mCRC) and liver metastases.

METHODS

Patient records from two Spanish centres were retrospectively examined for this analysis. Patients were included if they had stage IV mCRC with liver metastases, were unresectable or marginally resectable tumour before chemotherapy, and had oxaliplatin- or irinotecan-based chemotherapy, with or without bevacizumab, before resection. Tumour response was evaluated using response evaluation criteria in solid tumours (RECIST). Pathological response was assessed by pathologists blinded to treatment.

RESULTS

Ninety-five patients were included. Good pathological responses (PR0/PR1) were observed in 37 patients (39 %). The RECIST response rate was 51 %. Only 42 % of patients with a good pathological response had a complete or partial response according to RECIST, while 57 % of those with a poor pathological response had a complete or partial response according to RECIST. RECIST response rates were similar with and without bevacizumab, although 49 % of bevacizumab-treated patients had a good pathological response versus 27 % of those receiving chemotherapy alone (χ (2) P = 0.0302).

CONCLUSION

Pathological response may be a better indicator of treatment efficacy than RECIST for patients with mCRC receiving bevacizumab in the neoadjuvant setting. Adding bevacizumab to chemotherapy has the potential to increase pathological response rates. Well-designed prospective clinical studies are required to establish the efficacy and tolerability of this approach.

CA19-9 level as a prognostic and predictive factor of bevacizumab efficacy in metastatic colorectal cancer patients undergoing oxaliplatin-based chemotherapy

PURPOSE

The prognostic and predictive values of carbohydrate antigen 19-9 (CA19-9) levels in metastatic colorectal cancer (mCRC) remain unclear. We reviewed all mCRC patients at a single institution to evaluate the relationship between CA19-9 levels and survival.

METHODS

Two hundred and fifty-two patients underwent first-line chemotherapy using oxaliplatin-based regimens between April 2005 and December 2009. The relationship between baseline CA19-9 levels and survival was analyzed. Moreover, we evaluated the relationship between baseline CA19-9 levels and clinicopathological factors.

RESULTS

One hundred and fifty patients had elevated baseline CA19-9 levels (elevated group), and 79 patients had normal baseline CA19-9 (normal group) levels. Both KRAS and BRAF mutation rates were higher in the elevated group than in the normal group. Elevated CA19-9 level was a poor prognostic factor compared with normal CA19-9 levels (P = 0.0021). In the elevated group, the median survival time with bevacizumab was significantly longer with bevacizumab than without it (median OS, 27.8 vs. 15.3 months, P = 0.0019). However, the median survival time was not different with or without bevacizumab in the normal group (median OS, 36.5 vs. 38.0 months, P = 0.9515).

CONCLUSION

Our results suggest that baseline CA19-9 level is an independent prognostic factor in mCRC patients, and it correlated with the KRAS/BRAF mutation status. Bevacizumab exhibits clinical activity only for high CA19-9 levels in mCRC.

ROS1 and ALK fusions in colorectal cancer, with evidence of intratumoral heterogeneity for molecular drivers

Activated anaplastic lymphoma kinase (ALK) and ROS1 tyrosine kinases, through gene fusions, have been found in lung adenocarcinomas and are highly sensitive to selective kinase inhibitors. This study aimed at identifying the presence of these rearrangements in human colorectal adenocarcinoma specimens using a 4-target, 4-color break-apart FISH assay to simultaneously determine the genomic status of ALK and ROS1. Among the clinical colorectal cancer specimens analyzed, rearrangement-positive cases for both ALK and ROS1 were observed. The fusion partner for ALK was identified as EML4 and the fusion partner for one of the ROS1-positive cases was SLC34A2, the partner for the other ROS1-positive case remains to be identified. A small fraction of specimens presented duplicated or clustered copies of native ALK and ROS1. In addition, rearrangements were detected in samples that also harbored KRAS and BRAF mutations in two of the three cases. Interestingly, the ALK-positive specimen displayed marked intratumoral heterogeneity and rearrangement was also identified in regions of high-grade dysplasia. Despite the additional oncogenic events and tumor heterogeneity observed, elucidation of the first cases of ROS1 rearrangements and confirmation of ALK rearrangements support further evaluation of these genomic fusions as potential therapeutic targets in colorectal cancer.

IMPLICATIONS

ROS1 and ALK fusions occur in colorectal cancer and may have substantial impact in therapy selection.

BRAF mutation is associated with distinct clinicopathological characteristics in colorectal cancer: a systematic review and meta-analysis

AIM

Colorectal cancer is a heterogeneous disease with multiple underlying genetic mutations resulting in different phenotypes. Mutation in the v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) proto-oncogene is an important event in the methylator pathway. There is no consensus, however, on the clinicopathological characteristics associated with BRAF mutation.

METHOD

A comprehensive search for published studies examining the effect of BRAF mutation on colorectal cancer was performed. Random effects methods were used to combine data.

RESULTS

Data were retrieved from 21 studies describing 9885 patients. BRAF associated colorectal cancer is associated with proximal tumour location (OR 5.222, 95% CI 3.801-7.174, P < 0.001), T4 tumours (OR 1.761, 95% CI 1.164-2.663, P = 0.007) and poor differentiation (OR 3.816, 95% CI 2.714-5.365, P < 0.001) and is negatively associated with male sex (OR 0.623, 95% CI 0.505-0.769, P < 0.001), age of diagnosis under 60 years (OR 0.453, 95% CI 0.280-0.733, P = 0.001) and rectal cancer (OR 0.266, 95% CI 0.122-0.422, P < 0.001).

CONCLUSION

BRAF mutation appears to be associated with distinct, unfavourable clinicopathological characteristics in colorectal cancer.

Metastatic colorectal cancer first-line treatment with bevacizumab: the impact of K-ras mutation

BACKGROUND

Bevacizumab plus chemotherapy prolongs progression-free survival (PFS) and overall survival (OS) in metastatic colorectal cancer (mCRC). Although there is strong evidence to suggest that the mutational status of the K-ras oncogene has a role as a predictive factor for activity in patients treated with cetuximab and panitumumab, few data have been obtained in patients treated with bevacizumab. We conducted an additional retrospective analysis to investigate the prognostic value of K-ras mutation relative to mCRC first-line treatment with bevacizumab.

MATERIALS AND METHODS

A total of 108 patients were retrospectively reviewed. K-ras status was assessed in the overall population by sequencing. Statistical association for PFS and OS was analyzed using the Kaplan-Meier method, and the prognostic role of K-ras was determined using the logrank test.

RESULTS

Median PFS was 10 months both for patients with wild-type (WT) K-ras and mutated (MT) K-ras (hazard ratio [HR] 0.94, P=0.75); neither difference in median OS was significant (27 months WT K-ras versus 26 months MT K-ras, HR 0.92; P=0.70). A further analysis was carried out in the two groups according to metastatic sites. No statistically significant difference in terms of PFS and OS was demonstrated between WT K-ras and MT K-ras with liver metastases only and in those with extrahepatic disease.

CONCLUSION

Although further study is required, our results seem to confirm that K-ras mutation does not have a prognostic role in mCRC patients receiving first-line treatment with bevacizumab.

Incidence and prognostic impact of KRAS and BRAF mutation in patients undergoing liver surgery for colorectal metastases

BACKGROUND

Molecular biomarkers offer the potential for refining prognostic determinants in patients undergoing cancer surgery. Among patients with colorectal cancer, KRAS and BRAF are important biomarkers, but their role in patients undergoing surgical therapy for liver metastases is unknown. In this study, the incidence and prognostic significance of KRAS and BRAF mutations were determined in patients undergoing surgical therapy of colorectal liver metastases (CRLM).

METHODS

KRAS and BRAF analysis was performed on 202 patients undergoing surgery for CRLM between 2003 and 2008. Tumor samples were analyzed for somatic mutations using sequencing analysis (KRAS, codon12/13, BRAF, V600E). The frequency of mutations was ascertained, and their impact on outcome was determined relative to other clinicopathologic factors.

RESULTS

KRAS gene mutations were detected in 58/202 patients (29%). In contrast, mutation in the BRAF gene was identified in very low frequency in this surgical cohort, found in only 4/202 (2%) patients. On multivariate analysis, KRAS mutation was associated with worse survival (hazard ratio [HR], 1.99; 95% confidence interval [CI], 1.21-3.26), as well as recurrence risk (HR, 1.68; 95% CI, 1.04-2.70). Although other clinicopathologic features, including tumor number, carcinoembryonic antigen, and primary stage were also associated with survival, KRAS status remained independently predictive of outcome. The low incidence of BRAF mutation limited assessment of its prognostic impact.

CONCLUSION

Whereas KRAS mutations were found in approximately one third of patients, BFAF mutations were found in only 2% of patients undergoing surgery for CRLM. KRAS status was an independent predictor of overall and recurrence-free survival. Molecular biomarkers such as KRAS may help to refine our prognostic assessment of patients undergoing surgical therapy for CRLM.

Prognostic value of the combination of circulating tumor cells plus KRAS in patients with metastatic colorectal cancer treated with chemotherapy plus bevacizumab

OBJECTIVE

Circulating tumor cells (CTCs) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) status were identified as prognostic factors for progression-free survival (PFS) and overall survival (OS) in patients with metastatic colorectal cancer treated with chemotherapy and bevacizumab in analyses of the MACRO (Maintenance Treatment in Advanced Colorectal Cancer) trial. In this post hoc analysis of the MACRO trial, the potential additive effect of these 2 factors on patient outcomes was explored.

METHODS

A total of 158 of the 480 patients involved in the MACRO trial were included in the biological marker substudy. CTC isolation and enumeration were centralized and performed using the CellSearch System (Veridex LLC, Raritan, NJ) in 7.5 mL of whole blood. Evaluation of KRAS status was performed retrospectively by the standard method used at each center. PFS and OS were analyzed by the Kaplan-Meier method according to CTC count and KRAS status.

RESULTS

Patients with < 3 CTC per 7.5 mL blood at baseline and KRAS wild-type tumors had a median PFS of 14.2 months compared with 6.2 months in patients with ≥ 3 CTCs and KRAS mutated tumors (P < .0001; hazard ratio, 3.0; 95% confidence interval, 1.8-5.2). Similar findings were observed for OS (28.9 and 13.7 months, respectively, P = .0004; hazard ratio 2.8; 95% confidence interval, 1.6-4.9). Multivariate analyses showed that CTC count ≥ 3 and KRAS status were the only independent prognostic factors for both PFS and OS.

CONCLUSIONS

This post hoc analysis showed that CTC count and KRAS status were independent prognostic factors for outcomes in patients with metastatic colorectal cancer treated with bevacizumab ± chemotherapy. These factors should be taken into account in the design of future phase III trials.

A randomised phase III trial of the pharmacokinetic biomodulation of irinotecan using oral ciclosporin in advanced colorectal cancer: results of the Panitumumab, Irinotecan & Ciclosporin in COLOrectal cancer therapy trial (PICCOLO)

BACKGROUND

The main toxicity of irinotecan in advanced colorectal cancer (CRC) is delayed diarrhoea. Intestinal SN-38, released by deconjugation of the parent glucuronide excreted into the bile or produced in situ by intestinal carboxylesterase, is toxic to the intestinal epithelium. The canalicular transport of irinotecan and SN-38G is mediated by ABCC2 (MRP2) and ABCB1 (MDR1) which are both inhibited by ciclosporin. We tested whether irinotecan and ciclosporin was non-inferior for anti-cancer efficacy and superior for toxicity compared with single-agent irinotecan.

METHODS

Six hundred and seventy-two patients with advanced, measurable CRC following prior fluoropyrimidine-containing chemotherapy were randomised to either irinotecan 3-weekly 350 mg/m(2) (or 300 mg/m(2) if age >70 or performance status (PS)=2) or 3-weekly irinotecan at 140 mg/m(2) (120 mg/m(2) if age >70 or PS=2) with ciclosporin 3mg/kg t.d.s. for three days by mouth starting on the morning before irinotecan. The primary end-point was the proportion of patients alive and progression-free at 12 weeks. The key secondary end-point was the incidence of grade ≥3 diarrhoea within 12 weeks of randomisation.

RESULTS

The proportion of patients progression-free at 12 weeks with irinotecan was 53.4% compared to 47.2% with irinotecan plus ciclosporin (difference=-6.3%, 95% confidence interval (CI) [-13.8%, 1.3%]). Since the lower limit of the 95% CI crossed the pre-specified non-inferiority margin of -10.6%, non-inferiority of irinotecan plus ciclosporin compared to irinotecan alone was not statistically demonstrated. 15.0% patients developed severe diarrhoea on irinotecan compared to 13.8% on irinotecan plus ciclosporin, a non-significant difference.

INTERPRETATION

The pharmacokinetic biomodulation of irinotecan using oral ciclosporin does not improve the therapeutic index of irinotecan in advanced CRC.

FUNDING

The trial was funded by Cancer Research UK and supported by Amgen Pharma.

Microsatellite instability and BRAF mutation testing in colorectal cancer prognostication

BRAF mutation in colorectal cancer is associated with microsatellite instability (MSI) through its relationship with high-level CpG island methylator phenotype (CIMP) and MLH1 promoter methylation. MSI and BRAF mutation analyses are routinely used for familial cancer risk assessment. To clarify clinical outcome associations of combined MSI/BRAF subgroups, we investigated survival in 1253 rectal and colon cancer patients within the Nurses' Health Study and Health Professionals Follow-up Study with available data on clinical and other molecular features, including CIMP, LINE-1 hypomethylation, and KRAS and PIK3CA mutations. Compared with the majority subtype of microsatellite stable (MSS)/BRAF-wild-type, MSS/BRAF-mutant, MSI-high/BRAF-mutant, and MSI-high/BRAF-wild-type subtypes showed multivariable colorectal cancer-specific mortality hazard ratios of 1.60 (95% confidence interval [CI] =1.12 to 2.28; P = .009), 0.48 (95% CI = 0.27 to 0.87; P = .02), and 0.25 (95% CI = 0.12 to 0.52; P < .001), respectively. No evidence existed for a differential prognostic role of BRAF mutation by MSI status (P(interaction) > .50). Combined BRAF/MSI status in colorectal cancer is a tumor molecular biomarker for prognosic risk stratification.

Bevacizumab plus chemotherapy continued beyond first progression in patients with metastatic colorectal cancer previously treated with bevacizumab plus chemotherapy: ML18147 study KRAS subgroup findings

BACKGROUND

ML18147 evaluated continued bevacizumab with second-line chemotherapy for patients with metastatic colorectal cancer (mCRC) progressing after the standard first-line bevacizumab-containing therapy.

PATIENTS AND METHODS

Evaluating outcomes according to tumor Kirsten rat sarcoma virus oncogene (KRAS) status was an exploratory analysis. KRAS data were collected from local laboratories (using their established methods) and/or from a central laboratory (mutation-specific Scorpion amplification-refractory mutation system). No adjustment was made for multiplicity; analyses were not powered to detect statistically significant differences.

RESULTS

Of 820 patients, 616 (75%) had unambiguous KRAS data; 316 (51%) had KRAS wild-type tumors and 300 (49%) had mutant KRAS tumors. The median progression-free survival (PFS) was 6.4 months for bevacizumab plus chemotherapy and 4.5 months for chemotherapy [P < 0.0001; HR = 0.61; 95% confidence interval (CI): 0.49-0.77] for wild-type KRAS and 5.5 and 4.1 months, respectively (P = 0.0027; HR = 0.70; 95% CI: 0.56-0.89) for mutant KRAS. The median overall survival (OS) was 15.4 and 11.1 months, respectively (P = 0.0052; HR = 0.69; 95% CI: 0.53-0.90) for wild-type KRAS and 10.4 versus 10.0 months, respectively (P = 0.4969; HR = 0.92; 95% CI: 0.71-1.18) for mutant KRAS. In both analyses, no treatment interaction by KRAS status was observed (PFS, P = 0.4436; OS, P = 0.1266).

CONCLUSIONS

Bevacizumab beyond first progression represents an option for patients with mCRC treated with bevacizumab plus standard first-line chemotherapy, independent of KRAS status.

KRAS as prognostic biomarker in metastatic colorectal cancer patients treated with bevacizumab: a pooled analysis of 12 published trials

The significance of KRAS in advanced colorectal cancer (CRC) treated with bevacizumab (B) is not well understood. We conducted a systematic review and pooled analysis of published trials with the aim to assess the predictive and prognostic role of KRAS status in patients treated with B. We performed a systematic search of PubMed, EMBASE, Web of Science, and Cochrane Register of Controlled Trials. The primary endpoints included objective response rate (RR), progression-free survival (PFS), and overall survival (OS). The odds ratio (OR) for RR and hazard ratios (HRs) were calculated or extracted by published data either using a fixed effect model or a random effect model. A total of 12 studies were included. A total of 2,266 patients were analysed (54 % were KRAS wt). The pooled RRs for KRAS wild-type (wt) versus mutated (mut) patients were 54.8 and 48.3 %, respectively (OR 1.42, P = 0.02). Median PFS was significantly longer in KRAS wt patients compared with that in KRAS mut patients (HR = 0.85; 95 % confidence interval (CI) 0.74-0.98; P = 0.02). Similarly, median OS was significantly better in wt KRAS patients compared with that in mut KRAS patients (HR = 0.65; 95 % CI 0.46-0.92; P = 0.01). This pooled analysis of 12 published studies shows that KRAS wt status is a good prognostic factor for B-based chemotherapy. Also, KRAS wt CRC is associated with a better RR with B plus chemotherapy than mut counterpart.

The efficacy of additional bevacizumab to cytotoxic chemotherapy regimens for the treatment of colorectal cancer: an updated meta-analysis for randomized trials

BACKGROUND

The addition of bevacizumab (BEV) to cytotoxic chemotherapy regimens (CTX) was believed to be effective; however, its magnitude of benefits is still controversial. So a meta-analysis and systematic review seems to be necessary.

METHODS

PubMed and the Cochrane library were systematically searched. All relevant citations comparing CTX with/without BEV were considered for inclusion. Sensitivity and meta-regression analysis were performed to identify potential confounders. All pooled estimates were performed using a random-effects model. All statistical analyses were performed by StataSE 12.0.

RESULTS

The search strategy identified 10 eligible random control trials (RCTs) (n=1366). In our pooled estimates, the additional benefits of BEV to CTX were identified in overall survival (OS) hazard ratio (HR, 0.76; 95% CI, 0.69 to 0.82) and progression-free survival (PFS) (HR, 0.56; 95% CI, 0.51 to 0.60), and prolonged survival duration were also identified for OS (18.2 vs. 16.3, p=0.0003) and PFS (8.9 vs. 6.5, p<0.001). Subgroup analyses stratified by CTX was also performed, evident benefits of additional BEV in OS and PFS can be identified in all subgroups, except for the CTX containing capecitabine in OS. Moreover, the increased rate of incidence was also identified in hypertension, thrombosis, proteinuria, gastrointestinal perforation, and fatigue.

CONCLUSION

BEV, acting as a targeted agent to CTX, its additional benefit to CTX is at the cost of increased toxicity.

Systemic treatment of liver metastases from colorectal cancer

Patients presenting with synchronous or metachronous colorectal cancer liver metastases (CLM) should be evaluated for multimodal management with curative intent. Preoperative systemic chemotherapy shows beneficial impact on adjuvant progression-free survival and also borderline on overall survival, without significantly increasing initially R0 resectable patients postoperative complication rates. Postoperative chemotherapy recommended based on the perioperative trial experience for those patients achieving at least stable disease during preoperative chemotherapy, or based on the adjuvant trials for patients receiving upfront resection. 'Borderline' resectable CLM, preoperative chemotherapy plays an important role in both in achievement of a resectable status and improvement of prognosis. Recent 4 drug combinations demonstrated response rates up to 80% even for advanced disease and are thus promising regimens for further evaluation in patients with resectable or unresectable liver-limited (+/- lung) disease.

Improving outcomes in colorectal cancer: where do we go from here?

Colorectal cancer (CRC) places a considerable burden on individuals and society in Europe, being the second most common cause of cancer-related death in the region. While earlier diagnosis and advances in treatment have considerably improved survival in recent years, further progress is needed. One of the greatest challenges associated with the treatment of CRC is the fact that current therapies for advanced disease are not curative, necessitating treatment for many years and placing a significant healthcare burden on society. To reduce the burden of CRC, care delivery must be more efficient and cost-effective. In particular, development of adequate screening programmes is needed, along with chemo-preventative strategies and newer, more active therapies. Further challenges include the lack of optimal selection of patients for adjuvant therapy, identification of the most appropriate target populations for current treatments and the optimum sequence for new molecular targeted agents. This article outlines current developments and unmet needs in CRC, and provides a detailed vision for improvements in the management of the disease. Implementation of some of these strategies will go some way to improving outcomes for patients with CRC.

BRAF inhibitors in clinical oncology

Activating mutations of the BRAF oncogene are present in approximately 5-10% of all human malignancies and lead to constitutive activation of the mitogen activated protein kinase (MAPK) pathway. The introduction of BRAF inhibitors has greatly improved the short term prospects of some patients with these tumors, but the tumors tend to become resistant to therapy with time by activating alternative signaling pathways. Consequently, combination strategies with drugs that block not only the primary mutated BRAF kinase but also the alternative pathways implicated in development of resistance may represent a better strategy for improving survival in patients with tumors harboring BRAF mutations.

Molecular pathological epidemiology of epigenetics: emerging integrative science to analyze environment, host, and disease

Epigenetics acts as an interface between environmental/exogenous factors, cellular responses, and pathological processes. Aberrant epigenetic signatures are a hallmark of complex multifactorial diseases (including neoplasms and malignancies such as leukemias, lymphomas, sarcomas, and breast, lung, prostate, liver, and colorectal cancers). Epigenetic signatures (DNA methylation, mRNA and microRNA expression, etc) may serve as biomarkers for risk stratification, early detection, and disease classification, as well as targets for therapy and chemoprevention. In particular, DNA methylation assays are widely applied to formalin-fixed, paraffin-embedded archival tissue specimens as clinical pathology tests. To better understand the interplay between etiological factors, cellular molecular characteristics, and disease evolution, the field of 'molecular pathological epidemiology (MPE)' has emerged as an interdisciplinary integration of 'molecular pathology' and 'epidemiology'. In contrast to traditional epidemiological research including genome-wide association studies (GWAS), MPE is founded on the unique disease principle, that is, each disease process results from unique profiles of exposomes, epigenomes, transcriptomes, proteomes, metabolomes, microbiomes, and interactomes in relation to the macroenvironment and tissue microenvironment. MPE may represent a logical evolution of GWAS, termed 'GWAS-MPE approach'. Although epigenome-wide association study attracts increasing attention, currently, it has a fundamental problem in that each cell within one individual has a unique, time-varying epigenome. Having a similar conceptual framework to systems biology, the holistic MPE approach enables us to link potential etiological factors to specific molecular pathology, and gain novel pathogenic insights on causality. The widespread application of epigenome (eg, methylome) analyses will enhance our understanding of disease heterogeneity, epigenotypes (CpG island methylator phenotype, LINE-1 (long interspersed nucleotide element-1; also called long interspersed nuclear element-1; long interspersed element-1; L1) hypomethylation, etc), and host-disease interactions. In this article, we illustrate increasing contribution of modern pathology to broader public health sciences, which attests pivotal roles of pathologists in the new integrated MPE science towards our ultimate goal of personalized medicine and prevention.

Rare Though Not Mutually Exclusive: A Report of Three Cases of Concomitant KRAS and BRAF Mutation and a Review of the Literature

KRAS mutations occur frequently in colorectal cancers (CRC) and predict lack of response to anti-epidermal growth factor receptor (EGFR) monoclonal antibody therapy. CRC BRAF mutations, most commonly at V600E, occur less than 10% of the time, and occur usually in KRAS wild-type tumors, and more frequently in microsatellite instable tumors. Concomitant KRAS and BRAF mutant CRCs are rare (occurring in 0.001%); BRAF mutations should not be routinely tested in patients with KRAS mutant tumors, unless the patients is participating in a clinical trial enriching for the presence of a KRAS or BRAF tumor. Clinical trials treating patients with either KRAS or BRAF mutant tumors should address eligibility of patients with concomitant KRAS and BRAF mutations.

Prognostic impact and the relevance of PTEN copy number alterations in patients with advanced colorectal cancer (CRC) receiving bevacizumab

Loss of phosphatase and tensin homologue (PTEN) expression may be prognostic in colorectal cancer (CRC) and may have a correlation with vascular endothelial growth factor (VEGF) expression via hypoxia-inducible factor 1 (HIF-1) alpha, and the PI3K/mTOR pathways. We therefore have explored the prognostic association of PTEN loss and the potential that PTEN loss may be predictive of outcome with bevacizumab. Patients enrolled in the AGITG MAX trial, a randomized Phase III trial of capecitabine (C) +/− bevacizumab (B) (+/− mitomycin C [M]) with available tissues were analyzed for PTEN expression (loss vs. no loss) as assessed using a Taqman® copy number assay (CNA). Of the original 471 patients enrolled, tissues from 302 (64.1%) patients were analyzed. PTEN loss was observed in 38.7% of patients. There was no relationship between PTEN loss and KRAS or BRAF mutation. PTEN status was not prognostic for progression-free survival (PFS) or overall survival (OS) in multivariate analyses adjusting for other baseline factors; loss versus no loss PFS hazard ratio (HR) 0.9 (0.7–1.16), OS HR 1.04 (0.79–1.38). PTEN was not prognostic when assessed by KRAS and BRAF status. By using the comparison of C versus CB+CBM, PTEN status was not significantly predictive of the effectiveness of B for PFS or OS. PTEN status was not prognostic for survival in advanced colorectal cancer, irrespective of KRAS or BRAF status. PTEN status did not significantly predict different benefit with bevacizumb therapy.

KRAS mutations are associated with inferior clinical outcome in patients with metastatic colorectal cancer, but are not predictive for benefit with cediranib

PURPOSE

The prognostic potential of KRAS mutations in advanced colorectal cancer (CRC) patients and the impact of KRAS mutation status on the effectiveness of chemotherapy or vascular endothelial growth factor (VEGF) signalling inhibitor therapy remain unclear. KRAS mutation status was evaluated retrospectively as a potential prognostic/predictive marker of clinical outcomes using tumour samples from patients with metastatic CRC receiving cediranib or placebo plus FOLFOX/XELOX in a Phase III trial (HORIZON II; NCT00399035).

METHODS

KRAS codon 12 and 13 mutation analyses were performed using a commercially available, allele-specific, amplification refractory mutation system (ARMS)-based polymerase chain reaction (PCR) assay. Retrospective analyses of progression-free survival (PFS) and overall survival (OS) according to KRAS mutation status were performed for patients randomised to cediranib 20mg or placebo.

RESULTS

KRAS status was determined in 599/1076 patients (cediranib 20mg, n=285/502; cediranib 30 mg, n=110/216; placebo, n=204/358). Baseline characteristics were similar across KRAS mutant (n=258; 24.0%), wild-type (n=341; 31.7%) and status unknown (n=477; 44.3%) groups. There was a trend towards improved PFS and OS in the wild-type versus mutant subgroups independent of treatment (cediranib 20 mg and placebo: PFS hazard ratio (HR)=0.85 [median PFS: wild-type=8.5 months; mutant=8.3 months]; OS HR=0.71 [median OS: wild-type=20.9 months; mutant=16.9 months]). Treatment effects were similar between KRAS subgroups for cediranib 20mg versus placebo (PFS: wild-type HR=0.78, mutant HR=0.82; OS: wild-type HR=0.92, mutant HR=1.01).

CONCLUSION

Data from this large randomised Phase III study show that KRAS codon 12/13 mutations have negative prognostic value in metastatic CRC patients receiving treatment with FOLFOX/XELOX, but KRAS mutation status is not predictive of treatment benefit with cediranib, using PFS or OS.

Molecular markers to predict outcome to antiangiogenic therapies in colorectal cancer: current evidence and future perspectives

Angiogenesis is a universal requirement for the growth of solid tumours beyond the limits of oxygen diffusion from the existing vasculature. The expression and function of proangiogenic and antiangiogenic factors are altered in solid malignancies to drive net neoangiogenesis. Vascular endothelial growth factor (VEGF) has been confirmed in several clinical trials as an important therapeutic target in colorectal cancer (CRC) treatment. However, given that the efficacy of antiangiogenic agents appears to be limited to a subset of patients, the identification of who will obtain the greater benefit from this therapy or suffer from specific toxicities and when or for how long they should be administered in the treatment algorithm are major open questions for clinicians and challenges for present and future research. Current evidence indicates some predictive value for particular circulating measures, such as an increase in VEGF, a decrease in vascular endothelial growth factor receptor 2 (VEGFR-2) or circulating endothelial cells, tissue biomarkers, microvessel density, KRAS and BRAF gene mutations or polymorphisms affecting components of the VEGF pathway. Many questions relating to these and other surrogate biomarkers, however, remain unanswered and their clinical usefulness has yet to be proven. This review will focus on the present status of knowledge and future perspectives for developing molecular tools to foresee and monitor antiangiogenic therapy activity in CRC patients.

An Australian translational study to evaluate the prognostic role of inflammatory markers in patients with metastatic ColorEctal caNcer Treated with bevacizumab (Avastin™) [ASCENT]

Background

The use of bevacizumab in combination with fluoropyrimidine-containing chemotherapy is a well-established first-line and second-line treatment for patients with metastatic colorectal cancer (mCRC). However, there remains a need for reproducible, validated, inexpensive and accessible prognostic markers to aid treatment selection. The optimal treatment duration and the role of bevacizumab in certain patient subgroups, considered at particular risk of bevacizumab-mediated toxicity, also require further investigation. The aim of the ASCENT study [an Australian translational Study to evaluate the prognostic role of inflammatory markers in patients with metastatic ColorEctal caNcer Treated with bevacizumab (Avastin™)] is to evaluate the relationship between the host inflammatory response as measured by neutrophil/lymphocyte ratio (NLR) and treatment outcomes in patients with previously untreated mCRC receiving bevacizumab-based first- and second-line treatment.

Methods/design

This open-label, prospective, single arm, phase IV, Australian multi-centre study evaluates the relationship between the host inflammatory response as measured by NLR and treatment outcomes in patients with previously untreated mCRC receiving bevacizumab-based first- and second-line treatment. 150 patients will be recruited from 16 centres around Australia. Patients will receive trial treatments in two phases: Phase A: XELOX or mFOLFOX6 plus bevacizumab administered from study start until first disease progression; and Phase B: FOLFIRI plus bevacizumab administered from first disease progression until second disease progression. The primary analysis will test the association between NLR and progression free survival using a proportional Hazards Model. Secondary analyses will investigate whether the relationship can be improved upon with other prognostic biomarkers, and further characterise the safety of bevacizumab following treatment initiation, and when continued after progression in combination with standard chemotherapy regimens (presented through summary statistics and Kaplan Meier curves).

Discussion

Quantifying the relationship between NLR and PFS will inform decision making on the extent to which this simple metric may be applied clinically.

Trial registration

ClinicalTrials.gov: NCT01588990

Molecular dissection of microsatellite instable colorectal cancer

Colorectal cancer was one of the first solid tumors to be classified on the basis of molecular profiling. Microsatellite instability has allowed researchers to distinguish a specific subtype of colorectal cancer that has a clearly identified molecular origin (mismatch repair deficiency), arises on a hereditary and sporadic basis, is linked to a clear clinicopathologic profile, and has prognostic implications. Inconclusive predictive data along with a paucity of targeted drug development have prevented this molecular classification system from being implemented in the clinical setting. New high-throughput genomic data have validated it, thus stressing the fact that it is ready to be applied clinically.

SIGNIFICANCE

Application of a molecular classification of colorectal cancer in the clinical arena is an unmet promise. Recent results of large-scale genomic analyses have provided confirmation and further insights into the molecular biology of already known colorectal cancer subgroups. The quintessential example is the microsatellite instability subgroup, which has been well characterized during the past 2 decades. Future drug development and clinical research initiatives in colorectal oncology should consider these and other known cancer subgroups and start targeting these selected patient populations.

Bevacizumab plus chemotherapy in metastatic colorectal cancer patients treated in clinical practice

AIM

The effect of KRAS status on response to bevacizumab plus chemotherapy in metastatic colorectal cancer is still unclear. We aimed to evaluate the overall clinical response to such a therapy in clinical practice and assess the role of KRAS status on therapy response.

PATIENTS & METHODS

This was a retrospective study enrolling 108 metastatic colorectal cancer patients. KRAS mutation analysis was performed by PCR.

RESULTS

Overall, 41.7% of patients had stable disease, 39.8% a partial response, 3.7% a complete response and 14.8% disease progression. Both clinical benefit and objective response rate tended to be higher in patients with only hepatic metastases than those with extrahepatic or multiple metastases. Response to therapy would appear to be independent of KRAS status, but larger studies are needed.

CONCLUSION

Bevacizumab plus chemotherapy provides clinical benefit and objective response rate in patients with metastatic colorectal cancer independently of KRAS expression, especially in those patients with only liver metastases.

Markers of response for the antiangiogenic agent bevacizumab

Bevacizumab is the first antiangiogenic therapy proven to slow metastatic disease progression in patients with cancer. Although it has changed clinical practice, some patients do not respond or gradually develop resistance, resulting in rather modest gains in terms of overall survival. A major challenge is to develop robust biomarkers that can guide selection of patients for whom bevacizumab therapy is most beneficial. Here, we discuss recent progress in finding such markers, including the first results from randomized phase III clinical trials evaluating the efficacy of bevacizumab in combination with comprehensive biomarker analyses. In particular, these studies suggest that circulating levels of short vascular endothelial growth factor A (VEGF-A) isoforms, expression of neuropilin-1 and VEGF receptor 1 in tumors or plasma, and genetic variants in VEGFA or its receptors are strong biomarker candidates. The current challenge is to expand this first set of markers and to validate it and implement it into clinical practice. A first prospective biomarker study known as MERiDiAN, which will treat patients stratified for circulating levels of short VEGF-A isoforms with bevacizumab and paclitaxel, is planned and will hopefully provide us with new directions on how to treat patients more efficiently.

Targeted therapy in metastatic colorectal cancer -- an example of personalised medicine in action

In metastatic colorectal cancer (mCRC), an improved understanding of the underlying pathology and molecular biology has successfully merged with advances in diagnostic techniques and local/systemic therapies as well as improvements in the functioning of multidisciplinary teams, to enable tailored treatment regimens and optimized outcomes. Indeed, as a result of these advancements, median survival for patients with mCRC is now in the range of 20-24months, having approximately tripled in the last 20years. The identification of KRAS as a negative predictive marker for activity of epidermal growth factor receptor (EGFR)-targeted monoclonal antibodies (mAbs), such as panitumumab (Amgen, Thousand Oaks, USA) and cetuximab (ImClone, Branchburg, USA), has perhaps had the greatest impact on patient management. This meant that, for the first time, mCRC patients unlikely to respond to a targeted therapy could be defined ahead of treatment. Ongoing controversies such as whether patients with KRAS G13D- (or BRAF V600-) mutated tumours can still respond to EGFR-targeted mAbs and the potential impact of inter- and intra-tumour heterogeneity on tumour sampling show that the usefulness of KRAS as a biomarker has not yet been exhausted, and that other downstream biomarkers should be considered. Conversely, a predictive biomarker for anti-angiogenic agents such as bevacizumab (Genentech, San Francisco, USA) in the mCRC setting is still lacking. In this review we will discuss the discovery and ongoing investigation into predictive biomarkers for mCRC as well as how recent advances have impacted on clinical practice and ultimately the overall cost of treatment for these patients.

Predictive impact of circulating vascular endothelial growth factor in four phase III trials evaluating bevacizumab

PURPOSE

We evaluated the prognostic and predictive use of circulating VEGF-A levels in phase III trials of bevacizumab in colorectal cancer, lung cancer, and renal cell carcinoma.

METHODS

Baseline plasma samples from 1,816 patients were analyzed for VEGF-A using an ELISA, which recognizes the major isoforms with equivalent sensitivity. HR and 95% confidence intervals (CI) for study end points were estimated using Cox regression analysis. A subset of matched archival tumor samples was analyzed for VEGF-A expression using in situ hybridization.

RESULTS

Higher VEGF-A levels showed trends toward adverse prognostic significance in the control arms of multiple trials, reaching statistical significance for overall survival (OS) in AVF2107 (highest vs. lowest 50%: HR = 1.76; 95% CI, 1.28-2.41), AVAiL (HR = 1.52; 95% CI, 1.16-2.00), and AVOREN (HR = 1.67; 95% CI, 1.18-2.36). In predictive analyses, the HRs for progression-free survival were similar across low and high VEGF-A subgroups and favored bevacizumab-containing treatment. In the low VEGF-A subgroups, HRs (95% CIs) were 0.61 (0.43-0.87) in AVF2107, 0.71 (0.43-1.16) in E4599, 0.74 (0.59-0.94) in AVAiL (low-dose), 0.89 (0.70-1.13) in AVAiL (high-dose), and 0.56 (0.40-0.78) in AVOREN. Analyses of OS data have shown similar results. No correlation between primary tumor VEGF-A expression and plasma VEGF-A levels was observed.

CONCLUSIONS

In this comprehensive evaluation, pretreatment total circulating VEGF-A was prognostic for outcome in metastatic colorectal, lung, and renal cell cancers, but it was not predictive for bevacizumab-based treatment benefit.

Bevacizumab in colorectal cancer: current and future directions

Bevacizumab is a humanized monoclonal antibody to VEGF-A, an important therapeutic target through its proangiogenic effects on a variety of tumors. Bevacizumab has demonstrated clinically meaningful benefit in conjunction with chemotherapy for patients with metastatic colorectal cancer as well as other tumor types. Bevacizumab is a well-tolerated therapy with regard to toxicity, in keeping with its biological vascular effect. In this era of personalized medicine, current Phase II and III trials are further defining its role at various stages of metastatic disease and the optimal sequencing with cytotoxic and other targeted agents to achieve further improvements in patient outcome. Translational research for biomarker discovery and validation and further study into mechanisms of resistance are essential for future development and sustained benefit with this class of therapeutic agents.

Role of Kras status in patients with metastatic colorectal cancer receiving first-line chemotherapy plus bevacizumab: a TTD group cooperative study

BACKGROUND

In the MACRO study, patients with metastatic colorectal cancer (mCRC) were randomised to first-line treatment with 6 cycles of capecitabine and oxaliplatin (XELOX) plus bevacizumab followed by either single-agent bevacizumab or XELOX plus bevacizumab until disease progression. An additional retrospective analysis was performed to define the prognostic value of tumour KRAS status on progression-free survival (PFS), overall survival (OS) and response rates.

METHODOLOGY/PRINCIPAL FINDINGS

KRAS data (tumour KRAS status and type of mutation) were collected by questionnaire from participating centres that performed KRAS analyses. These data were then cross-referenced with efficacy data for relevant patients in the MACRO study database. KRAS status was analysed in 394 of the 480 patients (82.1%) in the MACRO study. Wild-type (WT) KRAS tumours were found in 219 patients (56%) and mutant (MT) KRAS in 175 patients (44%). Median PFS was 10.9 months for patients with WT KRAS and 9.4 months for patients with MT KRAS tumours (p=0.0038; HR: 1.40; 95% CI:1.12-1.77). The difference in OS was also significant: 26.7 months versus 18.0 months for WT versus MT KRAS, respectively (p=0.0002; HR: 1.55; 95% CI: 1.23-1.96). Univariate and multivariate analyses showed that KRAS was an independent variable for both PFS and OS. Responses were observed in 126 patients (57.5%) with WT KRAS tumours and 76 patients (43.4%) with MT KRAS tumours (p=0.0054; OR: 1.77; 95% CI: 1.18-2.64).

CONCLUSIONS/SIGNIFICANCE

This analysis of the MACRO study suggests a prognostic role for tumour KRAS status in patients with mCRC treated with XELOX plus bevacizumab. For both PFS and OS, KRAS status was an independent factor in univariate and multivariate analyses.