Efficacy of chemotherapy containing bevacizumab in patients with metastatic colorectal cancer according to programmed cell death ligand 1

BACKGROUND Bevacizumab,an anti-vascular endothelial growth factor(VEGF)monoclonal antibody,inhibits angiogenesis and reduces tumor growth.Serum VEGF-C,lactate dehydrogenase,and inflammatory markers have been reported as predictive markers related to bevacizumab treatment.Programmed cell death ligand 1(PD-L1)could act upon VEGF receptor 2 to induce cancer cell angiogenesis and metastasis.AIM To investigate the efficacy of bevacizumab-containing chemotherapy in patients with metastatic colorectal cancer(CRC)according to the expression of PD-L1.METHODS This analysis included CRC patients who received bevacizumab plus FOLFOX or FOLFIRI as first-line therapy between June 24,2014 and February 28,2022,at Samsung Medical Center(Seoul,South Korea).Analysis of patient data included evaluation of PD-L1 expression by the combined positive score(CPS).We analyzed the efficacy of bevacizumab according to PD-L1 expression status in patients with CRC.RESULTS A total of 124 patients was included in this analysis.Almost all patients were treated with bevacizumab plus FOLFIRI or FOLFOX as the first-line chemotherapy.While 77%of patients received FOLFOX,23%received FOLFIRI as backbone first-line chemotherapy.The numbers of patients with a PD-L1 CPS of 1 or more,5 or more,or 10 or more were 105(85%),64(52%),and 32(26%),respectively.The results showed no significant difference in progression-free survival(PFS)and overall survival(OS)with bevacizumab treatment between patients with PDL1 CPS less than 1 and those with PD-L1 CPS of 1 or more(PD-L1<1%vs PD-L1≥1%;PFS:P=0.93,OS:P=0.33),between patients with PD-L1 CPS less than 5 and of 5 or more(PD-L1<5%vs PD-L1≥5%;PFS:P=0.409,OS:P=0.746),and between patients with PD-L1 CPS less than 10 and of 10 or more(PD-L1<10%vs PD-L1≥10%;PFS:P=0.529,OS:P=0.568).CONCLUSION Chemotherapy containing bevacizumab can be considered as first-line therapy in metastatic CRC irrespective of PD-L1 expression.

Comparative effectiveness of immunotherapy and chemotherapy in patients with metastatic colorectal cancer stratified by microsatellite instability status

BACKGROUND Immunotherapy have demonstrated promising outcomes in patients with high microsatellite instability(MSI)(MSI-H)metastatic colorectal cancer.However,the comparative effectiveness of Immunotherapy and chemotherapy for patients with low MSI(MSI-L),and microsatellite stable(MSS)metastatic colorectal cancer remains unclear.AIM To investigate immunotherapy vs chemotherapy for treatment of MSI-L/MSS metastatic colorectal cancer,and to evaluate the success of immunotherapy against chemotherapy in managing MSI-H metastatic colorectal cancer during a follow-up of 50 months.METHODS We conducted a retrospective cohort study using the National Cancer Database(NCDB)to evaluate the overall survival(OS)of patients with metastatic colorectal cancer treated with immunotherapy or chemotherapy.The study population was stratified by MSI status(MSI-H,MSI-L,and MSS).Multivariable Cox proportional hazard models were used to assess the association between treatment modality and OS,adjusting for potential confounders.RESULTS A total of 21951 patients with metastatic colorectal cancer were included in the analysis,of which 2358 were MSI-H,and 19593 were MSI-L/MSS.In the MSI-H cohort,immunotherapy treatment(n=142)was associated with a significantly improved median OS compared to chemotherapy(n=860).After adjusting for potential confounders,immunotherapy treatment remained significantly associated with better OS in the MSI-H cohort[adjusted hazard ratio(aHR):0.57,95%confidence interval(95%CI):0.43-0.77,P<0.001].In the MSS cohort,no significant difference in median OS was observed between immunotherapy treatment and chemotherapy(aHR:0.94,95%CI:0.69-1.29,P=0.715).CONCLUSION In this population-based study using the NCDB,immunotherapy treatment was associated with significantly improved OS compared to chemotherapy in patients with MSI-H metastatic colorectal cancer,but not in those with MSI-L/MSS metastatic colorectal cancer.Further studies are warranted to determine the optimal therapeutic approach for patients with MSI-L/MSS metastatic colorectal cancer.

Emerging role of liquid biopsy in rat sarcoma virus mutated metastatic colorectal cancer:A case report

BACKGROUND In patients with metastatic colorectal cancer(mCRC),the treatment options are limited and have been proved to be affected by rat sarcoma virus(RAS)mutational status.In RAS wild-type(wt)patients,the combination of antiepidermal growth factor receptor(EGFR)monoclonal antibodies with chemotherapy(CT)is more effective than CT alone.On the other hand,RAS-mutated patients are not eligible for treatment with anti-EGFR antibodies.CASE SUMMARY Eleven patients with initially RAS-mutated mCRC were followed from diagnosis to May 2022.At the time of cell-free DNA determination,five patients had undergone one CT line,five patients had undergone two CT lines,and one patient had undergone three CT lines(all in combination with bevacizumab).At the second and third treatment lines[second line(2L),third line(3L)],patients with neo-RAS wt received a combination of CT and cetuximab.In neo-RAS wt patients treated with anti-EGFR,our findings indicated an increase in progression-free survival for both 2L and 3L(14.5 mo,P=0.119 and 3.9 mo,P=0.882,respectively).Regarding 2L overall survival,we registered a slight increase in neo-RAS wt patients treated with anti-EGFR(33.6 mo vs 32.4 mo,P=0.385).At data cut-off,two patients were still alive:A RAS-mutated patient undergoing 3L treatment and a neo-RAS wt patient who received 2L treatment with anti-EGFR(ongoing).CONCLUSION Our case series demonstrated that monitoring RAS mutations in mCRC by liquid biopsy may provide an additional treatment line for neo-RAS wt patients.

Successful cetuximab rechallenge in metastatic colorectal cancer:A case report

BACKGROUND Metastatic colorectal cancer(mCRC)treatment has been evolving and increasingly driven by tumor biology and gene expression analysis.Rechallenge with epidermal growth factor receptor(EGFR)inhibitors(anti-EGFR)represents a promising strategy for patients with RAS wild-type(RAS-wt)mCRC and circulating tumor DNA has emerged as a potential selection strategy.Herein,we report the case of a RAS-wt mCRC patient who had a successful response to cetuximab rechallenge.CASE SUMMARY Our patient was diagnosed with stage IV RAS-wt,microsatellite-stable rectosigmoid junction adenocarcinoma.He was started on first-line treatment with FOLFIRI and cetuximab and achieved partial response,allowing for a left hepatectomy(R0),followed by post-operative chemotherapy and an anterior resection;progression-free survival(PFS)of 16 months was obtained.Due to hepatic and nodal relapse,second-line treatment with FOLFOX and bevacizumab was started with partial response;metastasectomy was performed(R0),achieving a PFS of 11 months.After a 15 months anti-EGFR-free interval,FOLFIRI and cetuximab were reintroduced upon disease progression,again with partial response and a PFS of 16 months.Following extensive hepatic relapse,cetuximab was reintroduced and a marked clinical and analytical improvement was seen,after only one cycle.RASwt status was confirmed on circulating tumor DNA.The patient’s overall survival exceeded 5 years.CONCLUSION Our case provides real-world data to support cetuximab rechallenge in later lines of RAS-wt mCRC treatment.

Therapeutic strategies targeting the epidermal growth factor receptor signaling pathway in metastatic colorectal cancer

More than 1.9 million new colorectal cancer(CRC)cases and 935000 deaths were estimated to occur worldwide in 2020,representing about one in ten cancer cases and deaths.Overall,colorectal ranks third in incidence,but second in mortality.More than half of the patients are in advanced stages at diagnosis.Treatment options are complex because of the heterogeneity of the patient population,including different molecular subtypes.Treatments have included conventional fluorouracil-based chemotherapy,targeted therapy,immunotherapy,etc.In recent years,with the development of genetic testing technology,more and more targeted drugs have been applied to the treatment of CRC,which has further prolonged the survival of metastatic CRC patients.

Transcriptomic Analysis of Metastatic Colorectal Tumor with Low Mutational Burden

Objective:To identify potential drug targets for metastasis colorectal cancer(CRC)patients with low mutational burden by examining differences in immune-related gene expression.Methods:For this study,623 samples were collected from The Cancer Genome Atlas(TCGA)database,comprising tumor mutational burden(TMB),RNA sequencing(RNA-Seq),and clinical data.Differential gene expression analysis,Gene Ontology(GO),and Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analysis of the identified genes were conducted using the R package.Additionally,a comparative analysis of immune infiltrating cell composition in metastatic and non-metastatic groups was performed.Hub genes,exhibiting high levels of interaction,were selected using the Search Tool for the Retrieval of Interacting Genes/Proteins(STRING)database.The Drug Gene Interaction Database(DGIdb)was then utilized to estimate drugs targeting the identified hub genes.Results:The transcriptome data of 326 colorectal cancer patients with low TMB were analyzed,comprising 58 patients with metastasis and 268 patients without metastasis.Among the differential expression in 1,111 genes for patients with metastasis compared to those without metastasis,733 genes were upregulated,and 378 genes were downregulated.KEGG and GO enrichment analysis indicated significant differences in gene expression in CRC metastatic patients with low TMB compared to non-metastasis patients with low TMB.Enriched pathways included humoral immune response,immunoglobulin production,and regulation of AMPA receptor activity.Two genes related to interleukin-12 were identified through secondary enrichment for immune-related genes.Analysis of tumor-infiltrating immune cell data revealed significant differences in memory-activated T cell CD4 and T cell CD8.Conclusions:This analysis of RNA sequencing data and immune-filtrating cell data revealed significant differences between metastatic colorectal cancer patients with low TMB and their non-metastatic counterparts.These distinctions suggest the possibility of identifying more effective drugs or therapies for metastatic colorectal cancer patients with low TMB.

Systemic treatment for metastatic colorectal cancer

Significant progress has been achieved in the treatment of metastatic colorectal cancer(mCRC)patients during the last 20 years.There are currently numerous treatments available for the first-line treatment of mCRC.Sophisticated molecular technologies have been developed to reveal novel prognostic and predictive biomarkers for CRC.The development of next-generation sequencing and wholeexome sequencing,which are strong new tools for the discovery of predictive molecular biomarkers to facilitate the delivery of customized treatment,has resulted in tremendous breakthroughs in DNA sequencing technology in recent years.The appropriate adjuvant treatments for mCRC patients are determined by the tumor stage,presence of high-risk pathologic characteristics,microsatellite instability status,patient age,and performance status.Chemotherapy,targeted therapy,and immunotherapy are the main systemic treatments for patients with mCRC.Despite the fact that these novel treatment choices have increased overall survival for mCRC,survival remains optimal for individuals with non-metastatic disease.The molecular technologies currently being used to support our ability to practice personalized medicine;the practical aspects of applying molecular biomarkers to regular clinical practice;and the evolution of chemotherapy,targeted therapy,and immunotherapy strategies for the treatment of mCRC in the front-line setting are all reviewed here.

Mitomycin C and capecitabine: An additional option as an advanced line therapy in patients with metastatic colorectal cancer

BACKGROUND In recent years survival of patients with metastatic colorectal cancer(mCRC),though still limited,has improved significantly;clearly,when the disease becomes refractory to standard regimens,additional treatment options are needed.Studies have shown that mitomycin C(MMC),an antitumor antibiotic,and capecitabine,a precursor of 5-fluorouracil,may act synergistically in combination.The efficacy of MMC/capecitabine has been demonstrated in the first-line setting,but only a few small studies have tested it in the advanced-line setting,with contradictory results.received a median of 2 MMC/capecitabine cycles(range 0.5-9.0).Thirty-four patients(28.6%)experienced grade≥3 toxicity,including 2(1.7%)with grade 4;there was no drug-related mortality.The objective response rate was 0.8%,and the disease control rate,24.4%.Median progression-free survival(PFS)was 2.1 mo(range 0.2-20.3),and median overall survival,4.8 mo(range 0.2-27.5).The 6-month overall survival rate was 44%;8.7%of patients remained progression-free.Factors associated with longer PFS were lower gamma-glutamyl transferase level(P=0.030)and primary tumor location in the left colon(P=0.017).Factors associated with longer overall survival were lower gamma-glutamyl transferase level(P=0.022),left-colon tumor location(P=0.044),low-to-moderate histological grade(P=0.012),Eastern Cooperative Oncology Group performance status 0-1(P=0.036),and normal bilirubin level(P=0.047).CONCLUSION MMC/capecitabine is an active,available,and relatively safe regimen for use beyond standard lines of therapy in mCRC.Several clinical and laboratory parameters can identify patients more likely to benefit.

Classification of patients with metastatic colorectal cancer into consensus molecular subtypes into real-world: A pilot study

BACKGROUND Colorectal cancer is a complex disease with high mortality rates.Over time,the treatment of metastatic colorectal cancer(mCRC)has gradually improved due to the development of modern chemotherapy and targeted therapy regimens.However,due to the inherent heterogeneity of this condition,identifying reliable predictive biomarkers for targeted therapies remains challenging.A recent promising classification system—the consensus molecular subtype(CMS)system—offers the potential to categorize mCRC patients based on their unique biological and molecular characteristics.Four distinct CMS categories have been defined:immune(CMS1),canonical(CMS2),metabolic(CMS3),and mesenchymal(CMS4).Nevertheless,there is currently no standardized protocol for accurately classifying patients into CMS categories.To address this challenge,reverse transcription polymerase chain reaction(RT-qPCR)and next-generation genomic sequencing(NGS)techniques may hold promise for precisely classifying mCRC patients into their CMSs.AIM To investigate if mCRC patients can be classified into CMS categories using a standardized molecular biology workflow.METHODS This observational study was conducted at the University of Chile Clinical Hospital and included patients with unresectable mCRC who were undergoing systemic treatment with chemotherapy and/or targeted therapy.Molecular biology techniques were employed to analyse primary tumour samples from these patients.RT-qPCR was utilized to assess the expression of genes associated with fibrosis(TGF-βandβ-catenin)and cell growth pathways(c-MYC).NGS using a 25-gene panel(TumorSec)was performed to identify specific genomic mutations.The patients were then classified into one of the four CMS categories according to the clinical consensus of a Tumour Board.Informed consent was obtained from all the patients prior to their participation in this study.All techniques were conducted at University of Chile.RESULTS Twenty-six patients were studied with the techniques and then evaluated by the Tumour Board to determine the specific CMS.Among them,23%(n=6),19%(n=5),31%(n=8),and 19%(n=5)were classified as CMS1,CMS2,CMS3,and CMS4,respectively.Additionally,8%of patients(n=2)could not be classified into any of the four CMS categories.The median overall survival of the total sample was 28 mo,and for CMS1,CMS2,CMS3 and CMS4 it was 11,20,30 and 45 mo respectively,with no statistically significant differences between groups.CONCLUSION A molecular biology workflow and clinical consensus analysis can be used to accurately classify mCRC patients.This classification process,which divides patients into the four CMS categories,holds significant potential for improving research strategies and targeted therapies tailored to the specific characteristics of mCRC.

Evaluating combined bevacizumab and XELOX in advanced colorectal cancer: Serum markers carcinoembryonic antigen, carbohydrate antigen 125, carbohydrate antigen 199 analysis

BACKGROUND Colorectal cancer ranks third and second among common and fatal cancers.The treatment of metastatic colorectal cancer(mCRC)is generally based on XELOX in clinical practice,which includes capecitabine(CAP)and oxaliplatin.Serum tumor markers carcinoembryonic antigen(CEA),carbohydrate antigen(CA)125 and CA199 are prognostic factors for various tumors.AIM To investigate evaluating combined bevacizumab(BEV)and XELOX in advanced colorectal cancer:Serum markers CEA,CA125,CA199 analysis.METHODS In this retrospective study,a total of 94 elderly patients diagnosed with mCRC were recruited and subsequently categorized into two groups based on the distinct treatment modalities they received.The control group was treated with XELOX plus CAP(n=47),while the observation group was treated with XELOX plus CAP and BEV(n=47).Several indexes were assessed in both groups,including disease control rate(DCR),incidence of adverse effects,serum marker levels(CEA,CA125,and CA19)and progression-free survival(PFS).RESULTS After 9 wk of treatment,the serum levels of CEA,CA199 and CA125 in the observation group were significantly lower than those in the control group(P<0.05).Moreover,the PFS of the observation group(9.12±0.90 mo)was significantly longer than that of the control group(6.49±0.64 mo).Meanwhile,there was no statistically significant difference in the incidence of adverse reactions and DCR between the two groups during maintenance therapy(P>0.05).CONCLUSION On the basis of XELOX treatment,the combination of BEV and CAP can reduce serum tumor marker levels and prolong PFS in patients with mCRC.

Irinotecan, a key chemotherapeutic drug for metastatic colorectal cancer

Irinotecan hydrochloride is a camptothecin derivative that exerts antitumor activity against a variety of tumors. SN-38 produced in the body by carboxylesterase is the active metabolite of irinotecan. After irinotecan was introduced for the treatment of metastatic colorectal cancer(CRC) at the end of the last century,survival has improved dramatically. Irinotecan is now combined with 5-fluorouracil,oxaliplatin and several molecularly-targeted anticancer drugs,resulting in the extension of overall survival to longer than 30 mo. Severe,occasionally life-threatening toxicity occurs sporadically,even in patients in relatively good condition who have a low risk of chemotherapyinduced toxicity,often causing the failure of irinotecanbased chemotherapy. Clinical pharmacological studies have revealed that such severe toxicity is related to exposure to SN-38 and genetic polymorphisms in UDPglucuronosyltransferase 1A1 gene. The large interand intra-patient variability in systemic exposure to SN-38 is determined not only by genetic factors but also by physiological and environmental factors. This review first summarizes the roles of irinotecan in chemotherapy for metastatic CRC and then discusses the optimal dosing of irinotecan based on the aforementioned factors affecting systemic exposure to SN-38,with the ultimate goal of achieving personalized irinotecan-based chemotherapy.

Prognostic significance of the pre-chemotherapy lymphocyte-to-monocyte ratio in patients with previously untreated metastatic colorectal cancer receiving FOLFOX chemotherapy

Background:As a surrogate marker of systemic inflammation,the lymphocyte-to-monocyte ratio(LMR) is an independent prognostic factor for various malignancies.This study investigated the prognostic significance of the pre-chemotherapy LMR in patients with previously untreated metastatic colorectal cancer(mCRC) receiving chemotherapy.Methods:The present study included newly diagnosed mCRC patients treated between January 2005 and December 2013 with FOLFOX chemotherapy,specifically oxaliplatin 180 mg/m^2 on day 1,with leucovorin 400 mg/m^2administered as a 2-hour infusion before the administration of 5-fluorouracil 400 mg/m^2 as an intravenous bolus injection,and 5-fluorouracil 2400 mg/m^2 as a 46-h infusion immediately after 5-fluorouracil bolus injection.The LMR was calculated as the absolute count of lymphocytes divided by the absolute count of monocytes.COX proportional hazards analysis was performed to evaluate the association of LMR with survival outcomes.Results:A total of 488 patients were included.Patients with high pre-chemotherapy LMR experienced significant improvements in progression-free survival(PFS,9.2 vs.7.6 months,P < 0.001) and overall survival(OS,19.4 vs.16.6 months,P < 0.001) compared with patients with low pre-chemotherapy LMR.Subsequent COX multivariate analysis showed that high pre-chemotherapy LMR(>3.11) was an independent favorable prognostic factor for PFS and OS.Additionally,patients whose LMR remained high(high-high subgroup),increased(low-high subgroup),or decreased(high-low subgroup) following chemotherapy showed better results in terms of PFS and OS than patients whose LMR remained low(low-low subgroup) after chemotherapy.Conclusions:For patients with previously untreated mCRC receiving FOLFOX chemotherapy,an elevated pre-chemotherapy LMR is an independent favorable prognostic factor for PFS and OS,and changes in the LMR before and after chemotherapy seem to predict the benefit of chemotherapy.

Expert consensus on maintenance treatment for metastatic colorectal cancer in China

The impact of maintenance therapy on progression-free survival and overall survival as well as quality of life of Chinese patients with metastatic colorectal cancer has long been under discussion.Recently,some phase III clinical trials have revealed that maintenance therapy can significantly prolong the progression-free survival while maintain an acceptable safety profile.Based on this evidence and common treatment practice in China,we now generated one Expert Consensus on Maintenance Treatment for Metastatic Colorectal Cancer in China to further specify the necessity of maintenance therapy,suitable candidates for such treatment,and appropriate regimens.

Cetuximab plus FOLFOX6 or FOLFIRI in metastatic colorectal cancer: CECOG trial

AIM: To investigate efficacy and safety of cetuximab combined with two chemotherapy regimens in patients with unresectable metastatic colorectal cancer (mCRC). METHODS: Randomized patients received cetuximab with 5-fluorouracil (5-FU), folinic acid (FA) and oxaliplatin (FOLFOX) 6 (arm A, n = 74) or 5-FU, FA and irinotecan (FOLFIRI) (arm B, n = 77). KRAS mutation status was determined retrospectively in a subset of tumors (n = 117). RESULTS: No significant difference was found between treatment arms A and B in the progression-free survival (PFS) rate at 9 mo, 45% vs 34%; median PFS, 8.6 mo vs 8.3 mo [hazard ratio (HR) = 1.06]; overall response rate (ORR) 43% vs 45% [odds ratio (OR) = 0.93] and median overall survival (OS), 17.4 mo vs 18.9 mo (HR = 0.98). Patients with KRAS wild-type tumors demonstrated improved PFS (HR = 0.55, P = 0.0051), OS, (HR = 0.62, P = 0.0296) and ORR (53% vs 36%) and in arm A, improved PFS (HR = 0.49, P = 0.0196), OS (HR = 0.48, P = 0.0201) and ORR (56%vs 30%), compared with patients with KRAS mutated tumors. In arm B no significant differences were found in efficacy by KRAS mutation status. Treatment in arms A and B was generally well tolerated. CONCLUSION: This study confirms that combinations of cetuximab with FOLFOX6 or FOLFIRI are effective and significantly improve clinical outcome in KRAS wild-type compared with KRAS mutated mCRC.

Role of targeted therapy in metastatic colorectal cancer

Colorectal cancer(CRC) is a significant cause of cancer-related morbidity and mortality all over the world.Improvements of cytotoxic and biologic agents have prolonged the survival in metastatic CRC(mC RC),with a median overall survival of approximately 2 years and more in the past two decades.The biologic agents that have proven clinical benefits in m CRC mainly target vascular endothelial growth factor(VEGF) and epidermal growth factor receptor(EGFR).In particular,bevacizumab targeting VEGF and cetuximab and panitumumab targeting EGFR have demonstrated sig-nificant survival benefits in combination with cytotoxic chemotherapy in the first-line,second-line,or salvage setting.Aflibercept,ramucirumab,and regorafenib are also used in second-line or salvage therapy.Recent retrospective analyses have shown that KRAS or NRAS mutations were negative predictive markers for anti-EGFR therapy.Based on the evidence from large rand-omized clinical trials,personalized therapy is necessary for patients with m CRC according to their tumor biology and characteristics.The aim of this paper was to summarize the results of the major randomized clinical trials and highlight the benefits of the molecular targeted agents in patients with mC RC.

Role of cetuximab in first-line treatment of metastatic colorectal cancer

The treatment of metastatic colorectal cancer(mCRC)has evolved considerably in the last decade,currently allowing most mCRC patients to live more than two years.Monoclonal antibodies targeting the epidermal growth factor receptor(EGFR)and vascular endothelial growth factor play an important role in the current treatment of these patients.However,only antibodies directed against EGFR have a predictive marker of response,which is the mutation status of v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog(KRAS).Cetuximab has been shown to be effective in patients with KRAS wild-type mCRC.The CRYSTAL study showed that adding cetuximab to FOLFIRI(regimen of irinotecan,infusional fluorouracil and leucovorin)significantly improved results in the first-line treatment of KRAS wildtype mCRC.However,results that evaluate the efficacy of cetuximab in combination with oxaliplatin-based chemotherapy in this setting are contradictory.On the other hand,recent advances in the management of colorectal liver metastases have improved survival in these patients.Adding cetuximab to standard chemotherapy increases the response rate in patients with wild-type KRAS and can thus increase the resectability rate of liver metastases in this group of patients.In this paper we review the different studies assessing the efficacy of cetuximab in the first-line treatment of mCRC.

Mechanisms of resistance to anti-epidermal growth factor receptor inhibitors in metastatic colorectal cancer

The prognosis of patients with metastatic colorectal cancer (mCRC) remain poor despite the impressive improvement of treatments observed over the last 20 years that led to an increase in median overall survival from 6 mo, with the only best supportive care, to approximately 30 mo with the introduction of active chemotherapy drugs and targeted agents. The monoclonal antibodies (moAbs) cetuximab and panitumumab, directed against the epidermal growth factor receptor (EGFR), undoubtedly represent a major step forward in the treatment of mCRC, given the relevant efficacy in terms of progression-free survival, overall survival, response rate, and quality of life observed in several phase III clinical trials among different lines of treatment. However, the anti-EGFR moAbs were shown only to be effective in a subset of patients. For instance, KRAS and NRAS mutations have been identified as biomarkers of resistance to these drugs, improving the selection of patients who might derive a benefit from these treatments. Nevertheless, several other alterations might affect the response to these drugs, and unfortunately, even the responders eventually become resistant by developing secondary (or acquired) resistance in approximately 13-18 mo. Several studies highlighted that the landscape of responsible alterations of both primary and acquired resistance to anti-EGFR drugs biochemically converge into MEK-ERK and PIK3CA-AKT pathways. In this review, we describe the currently known mechanisms of primary and acquired resistance to anti-EGFR moAbs together with the various strategies evaluated to prevent, overcame or revert them.

KRAS mutation testing in metastatic colorectal cancer

The KRAS oncogene is mutated in approximately 35%-45% of colorectal cancers, and KRAS mutational status testing has been highlighted in recent years. The most frequent mutations in this gene, point substitutions in codons 12 and 13, were validated as negative predictors of response to anti-epidermal growth factor receptor antibodies. Therefore, determining the KRAS mutational status of tumor samples has become an essential tool for managing patients with colorectal cancers. Currently, a variety of detection methods have been established to analyze the mutation status in the key regions of the KRAS gene; however, several challenges remain related to standardized and uniform testing, including the selection of tumor samples, tumor sample processing and optimal testing methods. Moreover, new testing strategies, in combination with the mutation analysis of BRAF , PIK3CA and loss of PTEN proposed by many researchers and pathologists, should be promoted. In addition, we recommend that microsatellite instability, a prognostic factor, be added to the abovementioned concomitant analysis. This review provides an overview of KRAS biology and the recent advances in KRAS mutation testing. This review also addresses other aspects of status testing for determining the appropriate treatment and offers insight into the potential drawbacks of mutational testing.

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

AIM: To reviewing genetic and epigenetic make-up of metastatic colorectal cancers (mCRCs) addicted to epidermal growth factor receptor (EGFR) signalling.METHODS: The present study summarizes the potential value of prognostic and predictive biomarkers in selecting mCRC patients treated with anti-EGFR therapy. A meta-analysis was performed using a systematic search of PubMed, Medline and Web of Science to identify eligible papers until March 21st, 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”, “miRNA” 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 mCRCs. 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 mRNA levels of EGFR ligands, of activating mutations in other genes such as NRAS and PIK3CA. The prognostic value of selected microRNAs 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 mCRC and discusses the potential of new prognostic and predictive biomarkers in selecting patients treated with anti-EGFR therapy.

Capecitabine Maintenance Therapy after First-Line Chemotherapy in Patients with Metastatic Colorectal Cancer

Objective:To evaluate the efficacy and toxicity of capecitabine maintenance therapy in metastatic colorectal cancer(mCRC) patients.Methods:From June 2001 to November 2006,after they had achieved clinical response from first-line chemotherapy,patients with mCRC in our hospital received two different treatment strategies.Thirty-three patients in maintenance group were treated with capecitabine 1000 mg/m2 po bid d1-14,q21d.Fifty-two patients in non-maintenance group did not receive any further chemotherapy.Results:Patients in maintenance group and non-maintenance group both received FOLFOX,FOLFIRI and XELOX as first-line therapy.The median chemotherapy cycles the two groups received were the same(6 vs 6).The response rates of first-line chemotherapy were 33.3% in maintenance group and 32.7% in non-maintenance group.Patients in maintenance group received 3-9 cycles of capecitabine therapy(median cycle 4).29/33(87.9%) patients in maintenance group and 47/52(90.4%) in non-maintenance group received following second-line chemotherapy,and no patients underwent targeted therapy.The median survival time and TTP were 40.4 months(95%CI:24.2-56.6) and 9.0 months(95%CI:6.7-11.3) in maintenance group,as compared with 21.5 months(95%CI:14.9-28.0,P=0.015) and 6.5 months(95%CI:4.4-8.5,P=0.007) in non-maintenance group.No severe adverse event was observed in the capecitabine maintenance group.Conclusion:mCRC patients could benefit from capecitabine maintenance therapy by prolonging survival time and TTP.