Prognostic and predictive biomarkers in metastatic colorectal cancer anti-EGFR therapy

AIM: To reviewing genetic and epigenetic make-up of metastatic colorectal cancers(m CRCs) addicted to epidermal growth factor receptor(EGFR) signalling.METHODS: The present study summarizes the potential value of prognostic and predictive biomarkers in selecting m CRC patients treated with anti-EGFR therapy. A meta-analysis was performed using a systematic search of Pub Med, Medline and Web of Science to identify eligible papers until March 21 st, 2016 using these following terms: ‘‘colorectal cancer'', "predictive biomarkers' ', "anti-EGFR therapy", "KRAS", "NRAS'', "PIK3CA", "TP53", "PTEN", ‘‘EGFR", "MET", "HER2", "epiregulin", "amphiregulin", "prognostic biomarkers", "BRAF", "miR NA" and "antibody-dependent cell-mediated cytotoxicity(ADCC) activity". Two investigators independently evaluated and extracted data from each identified studies based on selected criteria of inclusion and exclusion. RESULTS: The introduction of agents targeting EGFR such as cetuximab and panitumumab increased overall survival of mC RCs. Nevertheless, it has firstly became evident that response rates to cetuximab regimens in unselected patient populations were typically lower than 30%. Clinical data confirmed the predictive value of RAS mutations for resistance to cetuximab and panitumumab leading to the license of these monoclonal antibodies exclusively for the management of patients with RAS-wild type colorectal cancers. So far the identification of predictive biomarkers have generated interesting, though preliminary and, at times, conflicting data on the importance of tumour mR NA levels of EGFR ligands, of activating mutations in other genes such as NRAS and PIK3 CA. The prognostic value of selected micro RNAs level and ADCC activity is under investigation, while the prognostic impact of BRAF status remains controversial.CONCLUSION: This review focuses on the personalized treatment of m CRC and discusses the potential of new prognostic and predictive biomarkers in selecting patients treated with anti-EGFR therapy.

Evaluation of antibody-dependent cell-mediatedcy totoxicity activity and cetuximab response in KRAS wildtype metastatic colorectal cancer patients

AIM:To investigate the prognostic role of invariant natural killer T(iNKT) cells and antibody-dependent cell-mediated cytotoxicity(ADCC) in wild type KRAS metastatic colorectal cancer(mC RC) patients treated with cetuximab.METHODS: Forty-one KRAS wt mC RC patients,treated with cetuximab and irinotecan-based chemotherapy in Ⅱ and Ⅲ lines were analyzed. Genotyping of single nucleotide polymorphism(SNP)s in the FCGR2A,FCGR3A and in the 3' untranslated regions of KRAS and mutational analysis for KRAS,BRAF and NRAS genes was determined either by sequencing or allelic discrimination assays. Enriched NK cells were obtained from lymphoprepperipheral blood mononuclear cell and iN KT cells were defined by co-expression of CD3,TCRVα24,TCRVβ11. ADCC was evaluated as ex vivo NK-dependent activity,measuring lactate dehydrogenase release.RESULTS: At basal,mCRC patients performing ADCC activity above the median level(71%) showed an improved overall survival(OS) compared to patients with ADCC below(median 16 vs 8 mo;P=0.026). We did not find any significant correlation of iN KT cells with OS(P=0.19),albeit we observed a trend to a longer survival after 10 mo in patients with iN KT above median basal level(0.382 cells/microliter). Correlation of OS and progression-free survival(PFS) with interesting SNPs involved in ADCC ability revealed not to be significant. Patients carrying alleles both with A in FCGR2 A and TT in FCGR3A presented a trend of longer PFS(median 9 vs 5 mo;P=0.064). Chemotherapy impacted both iN KT cells and ADCC activity. Their prognostic values get lost when we analysed them after 2 and 4 mo of treatment.CONCLUSION: Our results suggest a link between iN KT cells,basal ADCC activity,genotypes in FCGR2A and FCGR3A,and efficacy of cetuximab in KRAS wt mC RC patients.

Methylated PLK2 is a prognostic biomarker in taxane-treated breast cancers

Background:In search of potential biomarkers of drug responsiveness the tumour suppressor PLK2 has been identified as a mediator of taxane sensitivity in some tumour types,based on its role of G2M checkpoint regulation.Objective:The current study set out to evaluate PLK2 methylation in breast cancer treated with neo-adjuvant chemotherapy including a taxane,as a biomarker of disease progression.Methods:Silencing of PLK2 in MCF-7 cells followed by taxane treatment was assessed using apoptotic readout for proof of principle.DNA was extracted from 64 cases of diagnostic surgical FFPE sections.Using pyrosequencing,levels of PLK2 promoter methylation were measured.Results:Silencing of PLK2 resulted in a significantly reduced apoptotic response following paclitaxel treatment(compared with scramble transfected controls).An association with higher levels of CpG island promoter methylation was seen for those cases with a progression-free survival(PFS)of less than 12 months.Kaplan-Meier analysis showed there was an association between overall survival(OS)and level of methylation(p=.06).Conclusions:Thus,based on data obtained from this pilot study,further larger studies evaluating the utility of PLK2 methylation as a potential predictive biomarker in breast cancer are warranted.