Clinical biomarkers in oncology: focus on colorectal cancer

Recent advances in microfluidic methods in cancer liquid biopsy

Early cancer detection, its monitoring, and therapeutical prediction are highly valuable, though extremely challenging targets in oncology. Significant progress has been made recently, resulting in a group of devices and techniques that are now capable of successfully detecting, interpreting, and monitoring cancer biomarkers in body fluids. Precise information about malignancies can be obtained from liquid biopsies by isolating and analyzing circulating tumor cells (CTCs) or nucleic acids, tumor-derived vesicles or proteins, and metabolites. The current work provides a general overview of the latest on-chip technological developments for cancer liquid biopsy. Current challenges for their translation and their application in various clinical settings are discussed. Microfluidic solutions for each set of biomarkers are compared, and a global overview of the major trends and ongoing research challenges is given. A detailed analysis of the microfluidic isolation of CTCs with recent efforts that aimed at increasing purity and capture efficiency is provided as well. Although CTCs have been the focus of a vast microfluidic research effort as the key element for obtaining relevant information, important clinical insights can also be achieved from alternative biomarkers, such as classical protein biomarkers, exosomes, or circulating-free nucleic acids. Finally, while most work has been devoted to the analysis of blood-based biomarkers, we highlight the less explored potential of urine as an ideal source of molecular cancer biomarkers for point-of-care lab-on-chip devices.

A Phase Ib Dose-Escalation Study of Encorafenib and Cetuximab with or without Alpelisib in Metastatic BRAF-Mutant Colorectal Cancer

Preclinical evidence suggests that concomitant BRAF and EGFR inhibition leads to sustained suppression of MAPK signaling and suppressed tumor growth in BRAF^V600E colorectal cancer models. Patients with refractory BRAF^V600-mutant metastatic CRC (mCRC) were treated with a selective RAF kinase inhibitor (encorafenib) plus a monoclonal antibody targeting EGFR (cetuximab), with (n = 28) or without (n = 26) a PI3Kα inhibitor (alpelisib). The primary objective was to determine the maximum tolerated dose (MTD) or a recommended phase II dose. Dose-limiting toxicities were reported in 3 patients receiving dual treatment and 2 patients receiving triple treatment. The MTD was not reached for either group and the phase II doses were selected as 200 mg encorafenib (both groups) and 300 mg alpelisib. Combinations of cetuximab and encorafenib showed promising clinical activity and tolerability in patients with BRAF-mutant mCRC; confirmed overall response rates of 19% and 18% were observed and median progression-free survival was 3.7 and 4.2 months for the dual- and triple-therapy groups, respectively.Significance: Herein, we demonstrate that dual- (encorafenib plus cetuximab) and triple- (encorafenib plus cetuximab and alpelisib) combination treatments are tolerable and provide promising clinical activity in the difficult-to-treat patient population with BRAF-mutant mCRC. Cancer Discov; 7(6); 610-9. ©2017 AACR.See related commentary by Sundar et al., p. 558This article is highlighted in the In This Issue feature, p. 539.

The p53 isoform delta133p53ß regulates cancer cell apoptosis in a RhoB-dependent manner

The TP53 gene plays essential roles in cancer. Conventionally, wild type (WT) p53 is thought to prevent cancer development and metastasis formation, while mutant p53 has transforming abilities. However, clinical studies failed to establish p53 mutation status as an unequivocal predictive or prognostic factor of cancer progression. The recent discovery of p53 isoforms that can differentially regulate cell cycle arrest and apoptosis suggests that their expression, rather than p53 mutations, could be a more clinically relevant biomarker in patients with cancer. In this study, we show that the p53 isoform delta133p53ß is involved in regulating the apoptotic response in colorectal cancer cell lines. We first demonstrate delta133p53ß association with the small GTPase RhoB, a well-described anti-apoptotic protein. We then show that, by inhibiting RhoB activity, delta133p53ß protects cells from camptothecin-induced apoptosis. Moreover, we found that high delta133p53 mRNA expression levels are correlated with higher risk of recurrence in a series of patients with locally advanced rectal cancer (n = 36). Our findings describe how a WT TP53 isoform can act as an oncogene and add a new layer to the already complex p53 signaling network.

Serum Trefoil Factor 3 as a Protein Biomarker for the Diagnosis of Colorectal Cancer

Colorectal cancer is one of the most frequent causes of cancer-related deaths worldwide. Thus, there is a need for timely diagnosis and effective treatment. Our aim in the present study was to detect the serum level of trefoil factor 3 protein and evaluate the diagnostic accuracy of trefoil factor 3 in patients with colorectal cancer. We collected serum samples from 204 participants (127 patients with colorectal cancer, 35 patients with polyps, and 42 healthy controls). The levels of serum trefoil factor 3 and carcinoembryonic antigen expression were measured by enzyme-linked immunosorbent assay. Receiver operating characteristic curves were plotted to calculate the diagnostic accuracy of trefoil factor 3 in patients with colorectal cancer. The serum levels of trefoil factor 3 in patients with colorectal cancer (6.66 ± 2.4 ng/mL; P < .00l) and polyps (3.86 ± 1.3 ng/mL; P < .00l) were significantly increased compared to healthy controls (2.09 ± 1.0 ng/mL). Moreover, the area under the receiver operating characteristic curve for trefoil factor 3 was greater than carcinoembryonic antigen (0.889 vs 0.715). At a cutoff value of 5.591 ng/mL, the diagnostic sensitivity, specificity, and likelihood ratio of serum trefoil factor 3 for colorectal cancer was 74.2%, 94.8%, and 14.25, respectively. Furthermore, the serum trefoil factor 3 levels in early colorectal cancer (TNM stage I, 3.67 ± 1.27 ng/mL) were significantly increased compared to healthy controls ( P < .001); however, there was no significant difference compared to patients with polyps ( P = .576). We observed that the serum trefoil factor 3 levels decreased after surgery (6.66 ± 2.4 vs 4.48 ± 1.80 ng/mL; P < .001). In addition, high serum trefoil factor 3 levels were associated with poor tumor differentiation and clinical TNM stage ( P < .05). In conclusion, serum trefoil factor 3 is a promising biomarker for the diagnosis of colorectal cancer and prognosis of patients.

TP53 drives invasion through expression of its Δ133p53β variant

TP53 is conventionally thought to prevent cancer formation and progression to metastasis, while mutant TP53 has transforming activities. However, in the clinic, TP53 mutation status does not accurately predict cancer progression. Here we report, based on clinical analysis corroborated with experimental data, that the p53 isoform Δ133p53β promotes cancer cell invasion, regardless of TP53 mutation status. Δ133p53β increases risk of cancer recurrence and death in breast cancer patients. Furthermore Δ133p53β is critical to define invasiveness in a panel of breast and colon cell lines, expressing WT or mutant TP53. Endogenous mutant Δ133p53β depletion prevents invasiveness without affecting mutant full-length p53 protein expression. Mechanistically WT and mutant Δ133p53β induces EMT. Our findings provide explanations to 2 long-lasting and important clinical conundrums: how WT TP53 can promote cancer cell invasion and reciprocally why mutant TP53 gene does not systematically induce cancer progression.

DOI:http://dx.doi.org/10.7554/eLife.14734.001

Most cancers are caused by a build-up of mutations that are acquired throughout life. One gene in particular, called TP53, is the most commonly mutated gene in many types of human cancers. This suggests that TP53 mutations play an important role in cancer development.

It is widely considered that the TP53 gene normally stops tumors from forming, while mutant forms of the gene somehow promote cancer growth. Evidence from patients with cancer has shown, however, that the relationship between TP53 mutations and cancer is not that simple. Some very aggressive cancers that resist treatment and spread have a normal TP53 gene. Some cancers with a mutated gene do not spread and respond well to cancer treatments. Recent studies have shown that the normal TP53 gene produces many different versions of its protein, and that some of these naturally occurring forms are found more often in tumors that others. However, it was not clear if certain versions of TP53’s proteins contributed to the development of cancer.

Now, Gadea, Arsic, Fernandes et al. show that Δ133p53β, one version of the protein produced by the TP53 gene in human cells, helps tumor cells to spread to other organs. Tests of 273 tumors taken from patients with breast cancer revealed that tumors with the Δ133p53β protein were more likely to spread. Patients with these Δ133p53β-containing tumors were also more likely to develop secondary tumors at other sites in the body and to die within five years.

Next, a series of experiments showed that removing Δ133p53β from breast cancer cells grown in the laboratory made them less likely to invade, while adding it back had the opposite effect. The same thing happened in colon cancer cells grown in the laboratory. The experiments showed that Δ133p53β causes tumor cells with the normal TP53 gene or a mutated TP53 gene to spread to other organs.

Together the new findings help explain why some aggressive cancers develop even with a normal version of the tumor-suppressing TP53 gene. They also help explain why not all cancers with a mutant version of the TP53 gene go on to spread. Future studies will be needed to determine whether drugs that prevent the production of the Δ133p53β protein can help to treat aggressive cancers.

DOI:http://dx.doi.org/10.7554/eLife.14734.002

Immunohistochemistry as a reliable method for detection of BRAF-V600E mutation in melanoma: a systematic review and meta-analysis of current published literature

BACKGROUND

The BRAF-V600E mutation is associated with tumor aggressiveness and poor prognosis in melanoma patients. Identification of this mutation is clinically important as we now have Food and Drug Administration-approved targeted therapies, such as BRAF and MEK inhibitors, which have been shown to retard disease progression in these patients. Detection of BRAF-V600E by genetic analysis using polymerase chain reaction is the gold standard method for melanoma cases. However, immunohistochemistry (IHC) using a VE1 antibody is rapidly emerging as a trustworthy method for the determination of mutation status in patients' specimens. Our objective in this study was to assess the reliability of IHC compared with genetic methods for successful identification of BRAF-V600E mutation in melanoma tissue specimens.

METHODS

A literature search of PubMed, Web of Science, and Embase was performed for studies comparing IHC with genetic analysis for the detection of BRAF in melanoma patients published through May 28, 2015. Pooled sensitivity, specificity, diagnostic odds ratio, positive, and negative likelihood ratios were calculated using a bivariate model. Logit estimates of sensitivity and specificity with their respective variances were used to plot a hierarchical receiver operating characteristic curve and area under the curve. Heterogeneity was assessed using the Q- and I-squared statistics.

RESULTS

An initial literature search resulted in 287 articles. After two independent reviews and consensus-based discussion to resolve disparities, 21 studies involving a total of 1687 cases met the eligibility criteria and were included in the analysis. The pooled sensitivity of IHC for BRAF-V600E detection was 0.96; 95% confidence interval (CI, 0.94-0.98), specificity 1.00; 95% CI (0.97-1.00), positive likelihood ratio 194.2; 95% CI (37.6-1003.3), negative likelihood ratio 0.04; 95% CI (0.02-0.07), and diagnostic odds ratio 5503 (1199-25,263), as compared with genetic analysis. A high heterogeneity was observed between these studies (Q value of 40.17 & I(2) = 95%; 95% CI (91-99, P < 0.001) which may be explained by studies using different cutoff values for labeling IHC as positive. High accuracy of IHC was depicted by area under the curve in the receiver operating characteristic curve which was 0.99; 95 % CI (0.98-1.00).

CONCLUSIONS

Meta-analysis demonstrates that IHC is highly sensitive and specific for the detection of BRAF-V600E in melanoma cases. IHC is likely to be useful in BRAF mutation detection because it is highly comparable with the genetic methods. Any negative or low staining cases may be selected to undergo genetic analysis based on other clinical and histopathologic features.

Common BRAF(V600E)-directed pathway mediates widespread epigenetic silencing in colorectal cancer and melanoma

During cancer development, it is well established that many genes, including tumor suppressor genes, are hypermethylated and transcriptionally repressed, a phenomenon referred to as epigenetic silencing. In general, the factors involved in, and the mechanistic basis of, epigenetic silencing during cancer development are not well understood. We have recently described an epigenetic silencing pathway, directed by the oncogenic B-Raf proto-oncogene (BRAF) variant BRAF(V600E), that mediates widespread epigenetic silencing in colorectal cancer (CRC). Notably, the BRAF(V600E) mutation is also present in 50-70% of melanomas. Here, we show that the same pathway we identified in CRC also directs epigenetic silencing of a similar set of genes in BRAF-positive melanoma. In both CRC and melanoma, BRAF(V600E) promotes epigenetic silencing through up-regulation of v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog G (MAFG), a transcriptional repressor with sequence-specific DNA-binding activity. The elevated concentration of MAFG drives DNA binding on the promoter. Promoter-bound MAFG recruits a set of corepressors that includes its heterodimeric partner BTB and CNC homology 1, basic leucine zipper transcription factor 1 (BACH1), the chromatin remodeling factor chromodomain helicase DNA-binding protein 8 (CHD8), and the DNA methyltransferase DNMT3B, resulting in hypermethylation and transcriptional silencing. Our results reveal a common BRAF(V600E)-directed transcriptional regulatory pathway that mediates epigenetic silencing in unrelated solid tumors and provide strong support for an instructive model of oncoprotein-directed epigenetic silencing.

Distinct gene expression profiles of proximal and distal colorectal cancer: implications for cytotoxic and targeted therapy

Colorectal cancer (CRC) is a heterogeneous disease with genetic profiles and clinical outcomes dependent on the anatomic location of the primary tumor. How location impacts the molecular makeup of a tumor and how prognostic and predictive biomarkers differ between proximal versus distal colon cancers is not well established. We investigated the associations between tumor location, KRAS and BRAF mutation status, and the mRNA expression of proteins involved in major signaling pathways, including tumor growth (EGFR), angiogenesis (VEGFR2), DNA repair (ERCC1) and fluoropyrimidine metabolism (TS). FFPE tumor specimens from 431 advanced CRC patients were analyzed. The presence of 7 different KRAS base substitutions and the BRAF V600E mutation was determined. ERCC1, TS, EGFR and VEGFR2 mRNA expression levels were detected by RT-PCR. BRAF mutations were significantly more common in the proximal colon (p<0.001), whereas KRAS mutations occurred at similar frequencies throughout the colorectum. Rectal cancers had significantly higher ERCC1 and VEGFR2 mRNA levels compared to distal and proximal colon tumors (p=0.001), and increased TS levels compared to distal colon cancers (p=0.02). Mutant KRAS status was associated with lower ERCC1, TS, EGFR, and VEGFR2 gene expression in multivariate analysis. In a subgroup analysis, this association remained significant for all genes in the proximal colon and for VEGFR2 expression in rectal cancers. The mRNA expression patterns of predictive and prognostic biomarkers as well as associations with KRAS and BRAF mutation status depend on primary tumor location. Prospective studies are warranted to confirm these findings and determine the underlying mechanisms.

SALL4 as a new biomarker for early colorectal cancers

PURPOSE

Colorectal cancer (CRC) is one of the most common causes of cancer-related death worldwide, and there is an urgent need to identify critical diagnostic and prognostic factors for early detection of the disease. Our aim in this study was to elucidate absolute copy number of SALL4 mRNA in the peripheral blood and serum of CRC patients to evaluate its probable prognostic or diagnostic value for CRC.

METHODS

Peripheral mononuclear cells from 111 cases were examined using absolute quantitative real-time RT-PCR to assess the exact copy number of SALL4 and CEA mRNA. Receiver operator characteristic (ROC) curves were also depicted to detect the sensitivity and specificity of SALL4 mRNA.

RESULTS

The blood copy number of SALL4 in recruited CRC patients was significantly higher than healthy controls (p = 0.0001). This high copy number was not only inversely associated with the depth of tumor invasion (p = 0.045), but also was significantly correlated with the high grade of tumor differentiation (p = 0.029) and sex (p = 0.027). Furthermore, the copy number of SALL4 was elevated in all examined serum samples (p = 0.0001) in significant association with high grade of tumor differentiation (p = 0.026) and patients' age (p = 0.012). ROC analysis indicated 96.1 and 95% sensitivity and specificity of SALL4 for CRC screening, respectively.

CONCLUSION

Early detection of CRC is directly correlated to improved outcomes, increased survival rates and reduced mortality. Our results can introduce SALL4 as a critical biomarker for efficient screening of patients to detect early stages of CRC.

Anticancer activity of the type I insulin-like growth factor receptor antagonist, ganitumab, in combination with the death receptor 5 agonist, conatumumab

Agents targeting the insulin-like growth factor receptor type 1 (IGF1R) have shown antitumor activity. Based on the evidence for interaction between the IGF-1 and TRAIL pathways, we hypothesized that the combination of ganitumab (monoclonal antibody to IGF1R) with the pro-apoptotic death receptor 5 agonist, conatumumab, might increase antitumor response. Ganitumab and conatumumab were tested in combination in a Colo-205 xenograft model. Part 1 of the clinical study was a phase Ib program of three doses of conatumumab (1, 3, 15 mg/kg) in combination with 18 mg/kg ganitumab to determine the maximum tolerated dose (MTD) in patients with advanced solid tumors. Part 2 was conducted in six cohorts with advanced non-small cell lung cancer (squamous or non-squamous histology), colorectal cancer, sarcoma, pancreatic cancer, or ovarian cancer, treated at the recommended doses of the combination. The combination was significantly more active in the Colo-205 xenograft model than either single agent alone (p < 0.0015). In part 1 of the clinical study, no dose-limiting toxicities were observed and the MTD of conatumumab was 15 mg/kg in combination with 18 mg/kg ganitumab. In part 2, 78 patients were treated and there were no objective responses but 28 patients (36 %) had stable disease (median 46 days, range 0-261). The combination was well-tolerated with no new toxicities. In conclusion, the combination of ganitumab and conatumumab was well-tolerated but had no objective responses in the population tested. The successful future application of this combination of antitumor mechanisms may rely on the identification of predictive biomarkers.

Microfluidic platforms for biomarker analysis

Biomarkers have been described as characteristics, most often molecular, that provide information about biological states, whether normal, pathological, or therapeutically modified. They hold great potential to assist diagnosis and prognosis, monitor disease, and assess therapeutic effectiveness. While a few biomarkers are routinely utilised clinically, these only reflect a very small percentage of all biomarkers discovered. Numerous factors contribute to the slow uptake of these new biomarkers, with challenges faced throughout the biomarker development pipeline. Microfluidics offers two important opportunities to the field of biomarkers: firstly, it can address some of these developmental obstacles, and secondly, it can provide the precise and complex platform required to bridge the gap between biomarker research and the biomarker-based analytical device market. Indeed, adoption of microfluidics has provided a new avenue for advancement, promoting clinical utilisation of both biomarkers and their analytical platforms. This review will discuss biomarkers and outline microfluidic platforms developed for biomarker analysis.

Focus on genetic and epigenetic events of colorectal cancer pathogenesis: implications for molecular diagnosis

Originally, colorectal cancer (CRC) tumorigenesis was understood as a multistep process that involved accumulation of tumor suppressor genes and oncogenes mutations, such as APC, TP53 and KRAS. However, this assumption proposed a relatively limited repertoire of genetic alterations. In the last decade, there have been major advances in knowledge of multiple molecular pathways involved in CRC pathogenesis, particularly regarding cytogenetic and epigenetic events. Microsatellite instability, chromosomal instability and CpG island methylator phenotype are the most analyzed cytogenetic changes, while DNA methylation, modifications in histone proteins and microRNAs (miRNAs) were analyzed in the field of epigenetic alterations. Therefore, CRC development results from interactions at many levels between genetic and epigenetic amendments. Furthermore, hereditary cancer syndrome and individual or environmental risk factors should not be ignored. The difficulties in this setting are addressed to understand the molecular basis of individual susceptibility to CRC and to determine the roles of genetic and epigenetic alterations, in order to yield more effective prevention strategies in CRC patients and directing their treatment. This review summarizes the most investigated biomolecular pathways involved in CRC pathogenesis, their role as biomarkers for early CRC diagnosis and their possible use to stratify susceptible patients into appropriate screening or surveillance programs.

KRAS mutations: analytical considerations

Colorectal cancer (CRC) is the third most common cancer and the second most common cause of cancer death globally. Significant improvements in survival have been made in patients with metastasis by new therapies. For example, Cetuximab and Panitumumab are monoclonal antibodies that inhibit the epidermal growth receptor (EGFR). KRAS mutations in codon 12 and 13 are the recognized biomarkers that are analyzed in clinics before the administration of anti-EGFR therapy. Genetic analyses have revealed that mutations in KRAS predict a lack of response to Panitumumab and Cetuximab in patients with metastatic CRC (mCRC). Notably, it is estimated that 35-45% of CRC patients harbor KRAS mutations. Therefore, KRAS mutation testing should be performed in all individuals with the advanced CRC in order to identify the patients who will not respond to the monoclonal EGFR antibody inhibitors. New techniques for KRAS testing have arisen rapidly, and each technique has advantages and disadvantages. Herein, we review the latest published literature specific to KRAS mutation testing techniques. Since reliability and feasibility are important issues in clinical analyses. Therefore, this review also summarizes the effectiveness and limitations of numerous KRAS mutation testing techniques.

Massively parallel tumor multigene sequencing to evaluate response to panitumumab in a randomized phase III study of metastatic colorectal cancer

PURPOSE

To investigate whether EGF receptor (EGFR) pathway mutations predicted response to monotherapy with panitumumab, an anti-EGFR monoclonal antibody, in a randomized phase III study of metastatic colorectal cancer.

EXPERIMENTAL DESIGN

Using massively parallel multigene sequencing, we analyzed 320 samples for 9 genes, with multigene sequence data from 288 (90%) samples.

RESULTS

Mutation rates were: KRAS (45%), NRAS (5%), BRAF (7%), PIK3CA (9%), PTEN (6%), TP53 (60%), EGFR (1%), AKT1 (<1%), and CTNNB1 (2%). In the randomized study and open-label extension, 22 of 138 (16%) wild-type KRAS (codons 12/13/61) patients versus 0 of 103 mutant KRAS (codons 12/13) patients had objective responses. Of 6 mutant KRAS (codon 61) patients, 1 with a Q61H mutation achieved partial response during the extension. Among wild-type KRAS (codons 12/13/61) patients, 0 of 9 patients with NRAS mutations, 0 of 13 with BRAF mutations, 2 of 10 with PIK3CA mutations, 1 of 9 with PTEN mutations, and 1 of 2 with CTNNB1 mutations responded to panitumumab. No patients responded to best supportive care alone. Panitumumab treatment was associated with longer progression-free survival (PFS) among wild-type KRAS (codons 12/13/61) patients [HR, 0.39; 95% confidence interval (CI), 0.28-0.56]. Among wild-type KRAS patients, a treatment effect for PFS favoring panitumumab occurred in patients with wild-type NRAS (HR, 0.39; 95% CI, 0.27-0.56) and wild-type BRAF (HR, 0.37; 95% CI, 0.24-0.55) but not mutant NRAS (HR, 1.94; 95% CI, 0.44-8.44).

CONCLUSIONS

These results show the feasibility and potential clinical use of next-generation sequencing for evaluating predictive biomarkers.

KRAS mutation is present in a small subset of primary urinary bladder adenocarcinomas

AIMS

To determine whether KRAS mutations occur in primary bladder adenocarcinoma.

METHODS AND RESULTS

Twenty-six cases of primary urinary bladder adenocarcinoma were analysed. DNA was extracted from formalin-fixed, paraffin-embedded tissue and amplified with shifted termination assay technology, which recognizes wild-type or mutant target sequences and selectively extends detection primers with labelled nucleotides. A mutation in KRAS was found in three (11.5%) of 26 primary bladder adenocarcinomas. Two of these three cases exhibited a G13D mutation, whereas the remaining case contained a mutation in G12V. None of the ten cases of urothelial carcinoma with glandular differentiation displayed KRAS mutation. Colonic adenocarcinoma contained a KRAS mutation in 18 (33%) of 55 cases. There was no distinct difference with regard to grade, stage or outcome according to the limited clinicopathological data available. However, the two youngest patients, aged 32 and 39 years, in our study group, with a mean population age of 61 years, were found to have mutations in KRAS.

CONCLUSIONS

KRAS mutations are present in a small subset of primary urinary bladder adenocarcinomas. Future clinical trials for treatment of bladder adenocarcinoma, employing targeted therapies similar to those used for treatment of colon cancer, may also benefit from the predictive implications of KRAS mutational testing.

Phosphatase and tensin homolog expression related to cetuximab effects in colorectal cancer patients: A meta-analysis

AIM: To investigate the correlation between expression of phosphatase and tensin homolog (PTEN) and cetuximab effects in colorectal cancer.

METHODS: We searched PubMed, EMBASE and ASCO to identify eligible studies. Finally, 8 randomized control studies were included in the meta-analysis. STATA 10.0 Software was used to investigate heterogeneity among individual studies and to summarize all the studies. Risk ratios (RRs) and hazard ratios (HRs) with 95% confidence intervals (CIs) were used to assess the strength of the association.

RESULTS: Compared with 20 of 266 patients with loss of PTEN, 206 of 496 patients with intact PTEN protein expression had a better objective response rate to cetuximab-based therapy (RR, 4.75; 95% CI, 2.59-8.72; P < 0.001). PTEN positivity was associated with better progression-free survival (PFS) (HR, 0.675; 95% CI, 0.473-0.964; P = 0.031) but not with better overall survival (OS) (HR, 0.608; 95% CI, 0.411-0.899; P = 0.013). In patients with KRAS wild-type status, PTEN positivity did not predict a longer PFS or OS (PFS: HR, 0.707; 95% CI, 0.440-1.138; P = 0.154; OS: HR, 0.943; 95% CI, 0.646-1.377; P = 0.761).

CONCLUSION: Expression of PTEN is related to the effect of cetuximab in colorectal cancer patients and should be considered in treatment with cetuximab.

Molecular events in primary and metastatic colorectal carcinoma: a review

Colorectal cancer (CRC) is a heterogeneous disease, developing through a multipathway sequence of events guided by clonal selections. Pathways included in the development of CRC may be broadly categorized into (a) genomic instability, including chromosomal instability (CIN), microsatellite instability (MSI), and CpG island methylator phenotype (CIMP), (b) genomic mutations including suppression of tumour suppressor genes and activation of tumour oncogenes, (c) microRNA, and (d) epigenetic changes. As cancer becomes more advanced, invasion and metastases are facilitated through the epithelial-mesenchymal transition (EMT), with additional genetic alterations. Despite ongoing identification of genetic and epigenetic markers and the understanding of alternative pathways involved in the development and progression of this disease, CRC remains the second highest cause of malignancy-related mortality in Canada. The molecular events that underlie the tumorigenesis of primary and metastatic colorectal carcinoma are detailed in this manuscript.

Prognostic and predictive roles for circulating biomarkers in gastrointestinal cancer

Circulating tumor cells (CTCs) and circulating free DNA (cfDNA) have been studied as promising prognostic and predictive tumor-derived biomarkers in the bloodstream of patients with gastrointestinal malignancies because they may be an alternative noninvasive tool to tumor tissue biopsies. Quantification and molecular characterization of CTCs and cfDNA may provide additional insights into cancer biology, potentially revealing novel targets to individualize cancer care. The present article aims to review the biology and current methods to assess CTCs and cfDNA, and the efforts to establish both tumor-derived biomarkers as prognostic and predictive factors in esophageal, gastric and colorectal cancer.

High extracellular matrix metalloproteinase inducer/CD147 expression is strongly and independently associated with poor prognosis in colorectal cancer

As in most solid tumors, colorectal cancer prognosis strongly depends on the extent of local invasion and lymph node and distant metastases. Extracellular matrix metalloproteinase inducer (EMMPRIN) is a transmembrane glycoprotein that activates matrix metalloproteinases, a group of enzymes that play an important role in tumor invasion and metastasis formation. This study investigates the EMMPRIN expression in a large cohort of patients with colorectal cancer. Immunohistochemical analysis of tissue microarrays from 285 patients shows that increased EMMPRIN protein expression does not correlate with clinicopathologic parameters and is an independent prognostic factor of poor survival, with mean survival times of 103 months in EMMPRIN negative/low versus 57 months in EMMPRIN intermediate/high patients (P < .001). This pronounced association of increased EMMPRIN levels and--on average--a 45% reduction in overall survival could help improve the risk stratification in patients with colorectal cancer; moreover, the lack of correlations with classical measures of cancer invasion/spreading may suggest the relevance of alternative EMMPRIN pathways beyond matrix metalloproteinase activation.

Identification of a biomarker panel for colorectal cancer diagnosis

BACKGROUND

Malignancies arising in the large bowel cause the second largest number of deaths from cancer in the Western World. Despite progresses made during the last decades, colorectal cancer remains one of the most frequent and deadly neoplasias in the western countries.

METHODS

A genomic study of human colorectal cancer has been carried out on a total of 31 tumoral samples, corresponding to different stages of the disease, and 33 non-tumoral samples. The study was carried out by hybridisation of the tumour samples against a reference pool of non-tumoral samples using Agilent Human 1A 60-mer oligo microarrays. The results obtained were validated by qRT-PCR. In the subsequent bioinformatics analysis, gene networks by means of Bayesian classifiers, variable selection and bootstrap resampling were built. The consensus among all the induced models produced a hierarchy of dependences and, thus, of variables.

RESULTS

After an exhaustive process of pre-processing to ensure data quality--lost values imputation, probes quality, data smoothing and intraclass variability filtering--the final dataset comprised a total of 8, 104 probes. Next, a supervised classification approach and data analysis was carried out to obtain the most relevant genes. Two of them are directly involved in cancer progression and in particular in colorectal cancer. Finally, a supervised classifier was induced to classify new unseen samples.

CONCLUSIONS

We have developed a tentative model for the diagnosis of colorectal cancer based on a biomarker panel. Our results indicate that the gene profile described herein can discriminate between non-cancerous and cancerous samples with 94.45% accuracy using different supervised classifiers (AUC values in the range of 0.997 and 0.955).

Cell-free nucleic acids as biomarkers in cancer patients

DNA, mRNA and microRNA are released and circulate in the blood of cancer patients. Changes in the levels of circulating nucleic acids have been associated with tumour burden and malignant progression. In the past decade a wealth of information indicating the potential use of circulating nucleic acids for cancer screening, prognosis and monitoring of the efficacy of anticancer therapies has emerged. In this Review, we discuss these findings with a specific focus on the clinical utility of cell-free nucleic acids as blood biomarkers.

Targeted imaging of colorectal dysplasia in living mice with fluorescence microendoscopy

We validate specific binding activity of a fluorescence-labeled peptide to colorectal dysplasia in living mice using a miniature, flexible, fiber microendoscope that passes through the instrument channel of an endoscope. The microendoscope delivers excitation light at 473 nm through a fiber-optic bundle with outer diameter of 680 µm to collect en face images at 10 Hz with 4 µm lateral resolution. We applied the FITC-labeled peptide QPIHPNNM topically to colonic mucosa in genetically engineered mice that spontaneously develop adenomas. More than two-fold greater fluorescence intensity was measured from adenomas compared to adjacent normal-appearing mucosa. Images of adenomas showed irregular morphology characteristic of dysplasia.

Use of bevacizumab in metastatic colorectal cancer: report from the Mexican opinion and analysis forum on colorectal cancer treatment with bevacizumab (September 2009)

Colorectal cancer is one of the most common cancers worldwide, and although associated mortality rates in South American countries are generally among the lowest in the world, they are on the rise. The prognosis of patients diagnosed with metastatic colorectal cancer has improved markedly over the last 12 years, increasing from 5 months with best supportive care to almost 2 years with combination chemotherapy plus bevacizumab. New prognostic and predictive biomarkers have been identified to guide therapy. Prognostic markers indicate patient survival independent of therapy and include disease stage, mutational status, and carcinoembryonic antigen. More recently, predictive markers of treatment outcomes have been identified. The most studied are mutations of the KRAS and BRAF genes, which are associated with resistance to epidermal growth factor receptor-targeted therapy. Tumor blood vessels have a number of structural and functional abnormalities that result in increased tumor vascularity and growth driven by angiogenesis. The anti-vascular endothelial growth factor (VEGF) monoclonal antibody bevacizumab, which binds to and neutralizes VEGF-A, has become a central part of the treatment of metastatic colorectal cancer. The addition of bevacizumab to fluorouracil (5-FU)/leucovorin, irinotecan plus bolus 5-FU/leucovorin, or irinotecan plus infusional 5-FU/leucovorin significantly improves the overall survival of patients with previously untreated metastatic colorectal cancer. In addition, a significant increase in overall survival is seen when bevacizumab is added to oxaliplatin plus infusional 5-FU/leucovorin (FOLFOX) in patients with metastatic colorectal cancer who progressed on a non-bevacizumab-containing regimen. Although the majority of studies were performed prior to the identification of KRAS and BRAF as predictive biomarkers, subsequent analysis has shown the benefits of bevacizumab occur independently of the mutational status of these genes. In patients who have progressed on a bevacizumab-containing regimen, continuation of bevacizumab is significantly associated with an improved survival based on observational cohort studies. Surgical resection is recommended in patients with metastatic colorectal cancer where complete removal of tumors can be achieved. Perioperative chemotherapy using FOLFOX for 3 months before and 3 months after surgery is associated with a 9% improvement in 3-year survival. The use of chemotherapy in patients initially deemed unresectable has produced resection rates approaching 40%, and the addition of bevacizumab to chemotherapy in this setting is feasible, safe, and effective. In a study of 219 patients, the addition of bevacizumab to FOLFOX was associated with a significant increase in major or complete pathologic response compared with FOLFOX alone. Improvements in patient survival have changed the treatment paradigm for metastatic colorectal cancer. Newer approaches view treatment not as distinct lines of therapy but as a continuum that includes personalized treatment plans offering maintenance therapy and even drug holidays between aggressive treatment periods. This approach achieves similar efficacy outcomes with reduced toxicity, and investigation of the role of bevacizumab as maintenance therapy is ongoing.

Expression of phosphorylated Stat5 predicts expression of cyclin D1 and correlates with poor prognosis of colonic adenocarcinoma

PURPOSE

Constitutive activation of signal transducer and activator of transcription-5 (Stat5) was recently found to be associated with tumor progression through stimulating cell proliferation and preventing apoptosis. However, it is not clear how activated Stat5 is expressed in colon cancer. We aimed to investigate the correlation between phosphorylated Stat5 (p-Stat5) expression and cell cycle regulators (cyclin D1) expression in colonic adenocarcinoma and the relationship between expression of these two proteins and various clinicopathological parameters, including overall survival.

METHODS

P-Stat5 and cyclin D1 expression were determined by immunohistochemical staining from 169 cases of resected colonic adenocarcinoma specimens.

RESULTS

P-Stat5 expression correlated with cyclin D1 expression (r = 0.250, P = 0.001). P-Stat5-positive staining was associated with the depth of tumor invasion (P = 0.002). Univariate survival analysis showed that lymph node metastasis, distant metastasis, TNM stage (all P < 0.0001), T stage (P = 0.024), p-Stat5-positive expression (P = 0.002), and cyclin D1-positive expression (P = 0.039) were associated with shorter survival in patients with colonic adenocarcinoma. Multivariate survival analysis showed that only distant metastasis (P < 0.001; hazard ratio [HR] = 4.96), TNM stage (P < 0.001; HR = 9.80), and p-Stat5 overexpression (P = 0.020; HR = 1.84) were independent predictors of poor prognosis.

CONCLUSIONS

Our findings provide the first evidence that p-Stat5 may play an important role in cyclin D1 overexpression and contribute to colonic adenocarcinoma progression.

Oncolytic adenovirus research and applications

Cancer treatments have improved steadily, but still only few metastatic solid tumors can be cured. Apoptosis-resistant clones frequently develop following standard treatments. Resistance factors are shared between different treatment regimens and, therefore, loss of response can occur rapidly, despite changing the drug, and there is a tendency for crossresistance between modalities. Therefore, new agents with novel mechanisms of action are desperately needed. Oncolytic adenoviruses, featuring cancer-selective cell lysis and spread, constitute an interesting drug platform aimed towards the goals of tumor specificity, and have been engineered in a variety of ways to improve their selectivity and efficacy. They allow rational drug development by the genetic incorporation of targeting mechanisms that can exert their function at different stages of the viral replication cycle. Owing to their immunogenicity, adenoviruses are particularly attractive for immunostimulatory purposes.

Identification of serum angiopoietin-2 as a biomarker for clinical outcome of colorectal cancer patients treated with bevacizumab-containing therapy

Background:

The combination of chemotherapy with the vascular endothelial growth factor (VEGF) antibody bevacizumab is a standard of care in advanced colorectal cancer (CRC). However, biomarkers predicting outcome of bevacizumab-containing treatment are lacking. As angiopoietin-2 (Ang-2) is a key regulator of vascular remodelling in concert with VEGF, we investigated its role as a biomarker in metastatic CRC.

Methods:

Serum Ang-2 levels were measured in 33 healthy volunteers and 90 patients with CRC. Of these, 34 had metastatic disease and received bevacizumab-containing therapy. To determine the tissue of origin of Ang-2, quantitative real-time PCR was performed on microdissected cryosections of human CRC and in a murine xenograft model of CRC using species-specific amplification.

Results:

Ang-2 originated from the stromal compartment of CRC tissues. Serum Ang-2 levels were significantly elevated in patients with metastatic CRC compared with healthy controls. Amongst patients receiving bevacizumab-containing treatment, low pre-therapeutic serum Ang-2 levels were associated with a significant better response rate (82 vs 31% P<0.01), a prolonged median progression-free survival (14.1 vs 8.5 months; P<0.01) and a reduction of 91% in the hazard of death (P<0.05).

Conclusion:

Serum Ang-2 is a candidate biomarker for outcome of patients with metastatic CRC treated with bevacizumab-containing therapy, and it should be further validated to customise combined chemotherapeutic and anti-angiogenic treatment.

A review of the most promising biomarkers in colorectal cancer: one step closer to targeted therapy

Rapidly growing insights into the molecular biology of colorectal cancer (CRC) and recent developments in gene sequencing and molecular diagnostics have led to high expectations for the identification of molecular markers to be used in optimized and tailored treatment regimens. However, many of the published data on molecular biomarkers are contradictory in their findings and the current reality is that no molecular marker, other than the KRAS gene in the case of epidermal growth factor receptor (EGFR)- targeted therapy for metastatic disease, has made it into clinical practice. Many markers investigated suffer from technical shortcomings, resulting from lack of quantitative techniques to capture the impact of the molecular alteration. This understanding has recently led to the more comprehensive approaches of global gene expression profiling or genome-wide analysis to determine prognostic and predictive signatures in tumors. In this review, an update of the most recent data on promising biological prognostic and/or predictive markers, including microsatellite instability, epidermal growth factor receptor, KRAS, BRAF, CpG island methylator phenotype, cytotoxic T lymphocytes, forkhead box P3-positive T cells, receptor for hyaluronic acid-mediated motility, phosphatase and tensin homolog, and T-cell originated protein kinase, in patients with CRC is provided.