Hepatic arterial infusion pump chemotherapy for colorectal liver metastases: Revisiting traditional techniques to explore new frontiers

Hepatic arterial infusion(HAI)chemotherapy,first introduced in the 1980s,has gained recognition as an effective locoregional treatment for colorectal liver metastasis(CRLM).Initially used for unresectable liver metastases,HAI’s app-lication has expanded to the adjuvant setting following hepatic resection,with early studies indicating improved hepatic disease-free survival.Recent research demonstrates that combining HAI with modern systemic therapies enhances conversion to resectability and prolongs both recurrence-free and overall survival,even in heavily pretreated patients with diverse RAS mutational statuses.Person-alization through approaches like microsatellite instability status and dose mo-difications further optimize outcomes.However,the complexity of HAI requires expertise across multidisciplinary teams,limiting its widespread adoption to specialized centers.Ongoing clinical trials continue to investigate HAI’s role in CRLM management,highlighting its potential to become a cornerstone of liver-directed therapy.We explore how HAI chemotherapy,in combination with personalized medicine,can advance treatment strategies for metastatic colorectal cancer.

Current and future perspectives in the management and treatment of colorectal cancer

In this editorial,we reviewed the article by Fadlallah et al that was recently published in the World Journal of Clinical Oncology.The article provided a comprehensive and in-depth view of the management and treatment of colorectal cancer(CRC),one of the leading causes of cancer-related morbidity and mortality worldwide.The article analyzed the therapeutic modalities and their sequencing,focusing on total neoadjuvant therapy for locally advanced rectal cancer.It highlighted the role of immunotherapy in tumors with high microsatellite instability or deficient mismatch repair,addressing recent advances that have improved prognosis and therapeutic response in localized and metastatic CRC.Innovations in surgical techniques,advanced radiotherapy,and systemic agents targeting specific mutational profiles are also discussed,reflecting on how they revolutionized clinical management.Circulating tumor DNA has emerged as a promising tool for detecting minimal residual disease,prognosis,and therapeutic monitoring,solidifying its role in precision oncology.This review emphasized the importance of technological and therapeutic advancements in improving clinical outcomes and personalizing CRC treatment.

Mechanisms of myeloid-derived suppressor cell-mediated immunosuppression in colorectal cancer and related therapies

Severe immunosuppression is a hallmark of colorectal cancer(CRC).Myeloid-derived suppressor cells(MDSCs),one of the most abundant components of the tumor stroma,play an important role in the invasion,metastasis,and immune escape of CRC.MDSCs create an immunosuppressive microenvironment by inhibiting the proliferation and activation of immunoreactive cells,including T and natural killer cells,as well as by inducing the proliferation of immunosuppressive cells,such as regulatory T cells and tumor-associated macrophages,which,in turn,promote the growth of cancer cells.Thus,MDSCs are key contributors to the emergence of an immunosup-pressive microenvironment in CRC and play an important role in the breakdown of antitumor immunity.In this narrative review,we explore the mechanisms through which MDSCs contribute to the immunosuppressive microenvironment,the current therapeutic approaches and technologies targeting MDSCs,and the therapeutic potential of modulating MDSCs in CRC treatment.This study provides ideas and methods to enhance survival rates in patients with CRC.

Current landscape of preoperative neoadjuvant therapies for initial resectable colorectal cancer liver metastasis

Colorectal cancer liver metastasis(CRLM)presents a clinical challenge,and optimizing treatment strategies is crucial for improving patient outcomes.Surgical resection,a key element in achieving prolonged survival,is often linked to a heightened risk of recurrence.Acknowledging the potential benefits of preoperative neoadjuvant chemotherapy in managing resectable liver metastases,this approach has gained attention for its role in tumor downsizing,assessing biological behavior,and reducing the risk of postoperative recurrence.However,the use of neoadjuvant chemotherapy in initially resectable CRLM sparks ongoing debates.The balance between tumor reduction and the risk of hepatic injury,coupled with concerns about delaying surgery,necessitates a nuanced approach.This article explores recent research insights and draws upon the practical experiences at our center to address critical issues regarding considerations for initially resectable cases.Examining the criteria for patient selection and the judicious choice of neoadjuvant regimens are pivotal areas of discussion.Striking the right balance between maximizing treatment efficacy and minimizing adverse effects is imperative.The dynamic landscape of precision medicine is also reflected in the evolving role of gene testing,such as RAS/BRAF and PIK3CA,in tailoring neoadjuvant regimens.Furthermore,the review emphasizes the need for a multidisciplinary approach to navigate the comp-lexities of CRLM.Integrating technical expertise and biological insights is crucial in refining neoadjuvant strategies.The management of progression following neoadjuvant chemotherapy requires a tailored approach,acknowledging the diverse biological behaviors that may emerge.In conclusion,this review aims to provide a comprehensive perspective on the considerations,challenges,and advancements in the use of neoadjuvant chemotherapy for initially resectable CRLM.By combining evidencebased insights with practical experiences,we aspire to contribute to the ongoing discourse on refining treatment paradigms for improved outcomes in patients with CRLM.

Therapy for benign rectal anastomotic stricture after surgery for colorectal cancer:A systematic review

Objective:To evaluate various treatment methods for benign rectal anastomotic stricture(AS)following surgery for colorectal cancer.Method:A systematic review of the literature was conducted,focusing on studies that reported outcomes of different treatment modalities for benign AS.The PubMed,Embase,Scopus,China National Knowledge Infrastructure,and Cochrane Library databases were searched from January 2000 to December 2023.The inclusion criteria were studies involving human subjects,published in English,and reporting on therapeutic outcomes for benign AS.Results:A total of 19 papers identified a range of therapeutic strategies,including nonoperative anastomotic dilation,endoscopic balloon dilation(EBD),transanal minimally invasive surgery(TAMIS),selfexpandable metal stents(SEMS),endoscopic incision(EI)and newer techniques such as prostate resection instrumentation.Nonoperative anastomotic dilation can serve as an initial treatment for lower AS.EI demonstrated promise in cases where EBD was ineffective,providing an alternative method for managing AS.TAMIS and SEMS showed higher efficacy in refractory cases,with TAMIS being particularly effective for severe fibrotic or completely closed AS.The use of rigid instrumentation with an electric knife for transanal incisions demonstrated precision but lacked the flexibility needed for complex procedures.Conclusion:While traditional methods such as nonoperative anastomotic dilation and EBD remain firstline treatments for benign AS,advanced techniques such as EI,TAMIS,and SEMS offer promising alternatives,particularly in refractory cases.The choice of treatment should be tailored to individual patient conditions,with consideration for the technical expertise required and the potential for complications.

Photo-activated microtubule targeting drugs: Advancing therapies for colorectal cancer

Over the years immunotherapy has demonstrably improved the field of cancer treatment.However,achieving long-term survival for colorectal cancer(CRC)patients remains a significant unmet need.Combination immunotherapies incor-porating targeted drugs like MEK or multi-kinase inhibitors have offered some palliative benefit.Nevertheless,substantial gaps remain in the current therapeutic armamentarium for CRC.In recent years,there has been a surge of interest in exploring novel treatment strategies,including the application of light-activated drugs in conjunction with optical devices.This approach holds promise for achie-ving localized and targeted delivery of cytotoxic agents,such as microtubule-targeting drugs,directly to cancerous cells within the colon.

Combining chemotherapy and targeted therapies in metastatic colorectal cancer

Colorectal cancer remains one of the major causes of cancer death worldwide. During the past years, the development of new effective treatment options has led to a considerable improvement in the outcome of this disease. The advent of agents such as capecitabine, irinotecan, oxaliplatin, cetuximab and bevacizumab has translated into median survival times in the range of 2 years. Intense efforts have focused on identifying novel agents targeting specific growth factor receptors, critical signal transduction pathways or mediators of angiogenesis. In addition, several clinical trials have suggested that some of these molecularly targeted drugs can be safely and effectively used in combination with conventional chemotherapy. In this article we review various treatment options combining cytotoxic and targeted therapies currently available for patients with metastatic colorectal cancer.

Colorectal cancer:Recent advances in management and treatment

Colorectal cancer(CRC)is the third most common cancer worldwide,and the second most common cause of cancer-related death.In 2020,the estimated number of deaths due to CRC was approximately 930000,accounting for 10%of all cancer deaths worldwide.Accordingly,there is a vast amount of ongoing research aiming to find new and improved treatment modalities for CRC that can potentially increase survival and decrease overall morbidity and mortality.Current management strategies for CRC include surgical procedures for resectable cases,and radiotherapy,chemotherapy,and immunotherapy,in addition to their combination,for non-resectable tumors.Despite these options,CRC remains incurable in 50%of cases.Nonetheless,significant improvements in research techniques have allowed for treatment approaches for CRC to be frequently updated,leading to the availability of new drugs and therapeutic strategies.This review summarizes the most recent therapeutic approaches for CRC,with special emphasis on new strategies that are currently being studied and have great potential to improve the prognosis and lifespan of patients with CRC.

The role of intestinal flora on tumorigenesis,progression,and the efficacy of PD-1/PD-L1 antibodies in colorectal cancer

Intestinal flora affects the maturation of the host immune system,serves as a biomarker and efficacy predictor in the immunotherapy of several cancers,and has an important role in the development of colorectal cancer(CRC).Anti-PD-1/PD-L1 antibodies have shown satisfactory results in MSI-H/d MMR CRC but performed poorly in patients with MSS/p MMR CRC.In recent years an increasing number of studies have shown that intestinal flora has an important impact on anti-PD-1/PD-L1 antibody efficacy in CRC patients.Preclinical and clinical evidence have suggested that anti-PD-1/PD-L1 antibody efficacy can be improved by altering the composition of the intestinal flora in CRC.Herein,we summarize the studies related to the influence of intestinal flora on anti-PD-1/PD-L1 antibody efficacy in CRC and discuss the potential underlying mechanism(s).We have focused on the impact of the intestinal flora on the efficacy and safety of anti-PD-1/PD-L1 antibodies in CRC and how to better utilize the intestinal flora as an adjuvant to improve the efficacy of anti-PD-1/PD-L1 antibodies.In addition,we have provided a basis for the potential of the intestinal flora as a new treatment modality and indicator for determining patient prognosis.

Drug resistance and new therapies in colorectal cancer

Colorectal cancer(CRC) is often diagnosed at an advanced stage when tumor cell dissemination has taken place. Chemo-and targeted therapies provide only a limited increase of overall survival for these patients. The major reason for clinical outcome finds its origin in therapy resistance. Escape mechanisms to both chemo-and targeted therapy remain the main culprits. Here, we evaluate major resistant mechanisms and elaborate on potential new therapies. Amongst promising therapies is α-amanitin antibodydrug conjugate targeting hemizygous p53 loss. It becomes clear that a dynamic interaction with the tumor microenvironment exists and that this dictates therapeutic outcome. In addition, CRC displays a limited response to checkpoint inhibitors, as only a minority of patients with microsatellite instable high tumors is susceptible. In this review, we highlight new developments with clinical potentials to augment responses to checkpoint inhibitors.

Gene therapy for human colorectal carcinoma using human CEA promoter controlled bacterial ADP-ribosylating toxin genes:PEA and DTA gene transfer

AIM To establish a tissue-specific gene therapy for colorectal carcinoma using bacterial ADP-ribosylating toxin genes.METHODS Pseudomonas exotoxin A domain Ⅱ+Ⅲ (PEA) was cloned from genomic DNA of Pseudomonas aeruginosa. PEA and diphtheria toxin A chain gene (DTA) were modified to express eukaryotically. After sequencing, the toxin genes under the control of human carcinoembryonic antigen (CEA) promoter were cloned into retroviral vectors to construct CEAPEA and CEADTA respectively. In vitro cotransfection of the constructs with luciferase vectors and in vivo gene transfer in nude mice were subsequently carried out.RESULTS Both CEAPEA and CEADTA specifically inhibited the reporter gene expression in the CEA positive human colorectal carcinoma (CRC) cells in vitro. Direct injection of CEAPEA and CEADTA constructs into the established human tumors in BALB/c nude mice led to significant and selective reductions in CRC tumor size as compared with that in control groups.CONCLUSION The toxin genes, working as therapeutic genes, are suitable for the tissue-specific gene therapy for colorectal carcinoma.

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.

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.

Toll-like receptor signaling in colorectal cancer:carcinogenesis to cancer therapy

Toll-like receptors (TLRs) are germ line encoded innate immune sensors that recognize conserved microbial structures and host alarmins, and signal expression of major histocompatibility complex proteins, costimulatory molecules, and inflammatory mediators by macrophages, neutrophils, dendritic cells, and other cell types. These protein receptors are characterized by their ability to respond to invading pathogens promptly by recognizing particular TLR ligands, including flagellin and lipopolysaccharide of bacteria, nucleic acids derived from viruses, and zymosan of fungi. There are 2 major TLR pathways; one is mediated by myeloid differentiation factor 88 (MYD88) adaptor proteins, and the other is independent of MYD88. The MYD88-dependent pathway involves early-phase activation of nuclear factor of kappa light polypeptide gene enhancer in B-cells 1 (NF-κB1) and all the TLRs, except TLR3, have been shown to activate this pathway. TLR3 and TLR4 act via MYD88-independent pathways with delayed activation of NF-κB signaling. TLRs play a vital role in activating immune responses. TLRs have been shown to mediate inflammatory responses and maintain epithelial barrier homeostasis, and are highly likely to be involved in the activation of a number of pathways following cancer therapy. Colorectal cancer (CRC) is one of the most common cancers, and accounts for almost half a million deaths annually worldwide. Inflammation is considered a risk factor for many common malignancies including cancers of the colorectum. The key molecules involved in inflammation-driven carcinogenesis include TLRs. As sensors of cell death and tissue remodeling, TLRs may have a universal role in cancer; stimulation of TLRs to activate the innate immune system has been a legitimate therapeutic strategy for some years. TLRs 3/4/7/8/9 are all validated targets for cancer therapy, and a number of companies are developing agonists and vaccine adjuvants. On the other hand, antagonists may favor inhibition of signaling responsible for autoimmune responses. In this paper, we review TLR signaling in CRC from carcinogenesis to cancer therapy.

Immunotherapy in human colorectal cancer: challenges and prospective

Human colorectal cancer(CRC) is the third most commonly diagnosed malignancies and the prognosis for patients with recurrent or metastatic disease is extremely poor. Although new chemotherapeutic regimen improves survival rates, therapy with better efficacy and less adverse effects is drastically needed. Immunotherapy has been investigated in human CRC for decades with limited success. However, recent developments of immunotherapy, particularly immune checkpoint inhibitor therapy, have achieved promising clinical benefits in many types of cancer and revived the hope for utilizing such therapy in human CRC. In this review, we will discuss important immunological landscape within the CRC microenvironment and introduce immunoscore system to better describe immunophenotyping in CRC. We will also discuss different immunotherapeutic approaches currently utilized in different phases of clinical trials. Some of those completed or ongoing trials are summarized. Finally, we provide a brief prospective on the future human CRC immunotherapy.

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.

Anti-EGFR and anti-VEGF agents:Important targeted therapies of colorectal liver metastases

Colorectal liver metastasis (CLM) is common worldwide. Targeted therapies with monoclonal antibodies have been proven effective in numerous clinical trials, and are now becoming standards for patients with CLM. The development and application of anti-epidermal growth factor receptor (anti-EGFR) and anti-vascular endothelial growth factor (anti-VEGF) antibodies represents significant advances in the treatment of this disease. However, new findings continue to emerge casting doubt on the efficacy of this approach. The Kirsten rat sarcoma viral oncogene (KRAS) has been proven to be a crucial predictor of the success of anti-EGFR treatment in CLM. Whereas a recent study summarized several randomized controlled trials, and showed that patients with the KRAS G13D mutation significantly benefited from the addition of cetuximab in terms of progress-free survival (PFS, 4.0 mo vs 1.9 mo, HR = 0.51, P = 0.004) and overall survival (OS, 7.6 mo vs 5.7 mo, HR = 0.50, P = 0.005). Some other studies also reported that the KRAS G13D mutation might not be absolutely predictive of non-responsiveness to anti-EGFR therapy. At the same time, “new” RAS mutations, including mutations in neuroblastoma RAS viral (v-ras) oncogene homolog (NRAS) and exons 3 and 4 of KRAS, have been suggested to be predictors of a poor treatment response. This finding was first reported by the update of the PRIME trial. The update showed that for patients with non-mutated KRAS exon 2 but other RAS mutations, panitumumab-fluorouracil, leucovorin, and oxaliplatin (FOLFOX)4 treatment led to inferior PFS (HR = 1.28, 95%CI: 0.79-2.07) and OS (HR = 1.29, 95%CI: 0.79-2.10), which was consistent with the findings in patients with KRAS mutations in exon 2. Then, the update of the PEAK trial and the FIRE-III trial also supported this finding, which would reduce candidates for anti-EGFR therapy but enhance the efficacy. In first-line targeted combination therapy, the regimens of cetuximab plus FOLFOX was called into question because of the inferior prognosis in the COIN trial and the NORDIC-VII trial. Also, bevacizumab plus oxaliplatin-based chemotherapy was questioned because of the NO16966 trial. By the update and further analysis of the COIN trial and the NORDIC-VII trial, cetuximab plus FOLFOX was reported to be reliable again. But bevacizumab plus oxaliplatin-based chemotherapy was still controversial. In addition, some trials have reported that bevacizumab is not suitable for conversion therapy. The results of the FIRE-III trial showed that cetuximab led to a significant advantage over bevacizumab in response rate (72% vs 63%, P = 0.017) for evaluable population. With the balanced allocation of second-line treatment, the FIRE-III trial was expected to provide evidence for selecting following regimens after first-line progression. There is still no strong evidence for the efficacy of targeted therapy as a preoperative treatment for resectable CLM or postoperative treatment for resected CLM, although the combined regimen is often administered based on experience. Combination therapy with more than one targeted agent has been proven to provide no benefit, and even was reported to be harmful as first-line treatment by four large clinical trials. However, recent studies reported positive results of erlotinib plus bevacizumab for maintenance treatment. The mechanism of antagonism between different targeted agents deserves further study, and may also provide greater understanding of the development of resistance to targeted agents.

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.

Perioperative restricted fluid therapy preserves immunological function in patients with colorectal cancer

AIM: To investigate the effect of perioperative restricted fluid therapy on circulating CD4+/CD8+ T lymphocyte ratio, percentage of regulatory T cells (Treg) and postoperative complications in patients with colorectal cancer.

Tumor budding predicts response to anti-EGFR therapies in metastatic colorectal cancer patients

AIM:To investigate whether the evaluation of tumor budding can complement K-RAS analysis to improve the individualized prediction of response to anti-epidermal growth factor receptor based therapies in metastatic colorectal cancer (mCRC) patients. METHODS:Forty-three patients with mCRC treated with cetuximab or panitumumab were entered into this study. According to the Response Evaluation Criteria in Solid Tumors criteria, 30 patients had stable or progressive disease (non-responsive), while 13 patients had a partial response. Tumor buds were evaluated from whole tissue sections stained for pan-cytokeratin, evaluated in the densest region using a 40 × objective and "high-grade" tumor budding was defi ned as 15 buds/high-power f ield.RESULTS: Tumor buds and K-RAS mutation both correctly classif ied 68% of patients. All patients with K-RAS mutation (n=7) or high-grade tumor budding (n=11) were non-responsive, of which 4 patients had both features. All 13 partial responders were K-RAS wild-type with low-grade tumor budding. Combined, the predictive value of K-RAS and tumor budding was 80%. Additionally, high-grade tumor budding was significantly related to worse progression-free survival [HR (95% CI): 2.8 (1.3-6.0, P=0.008)].CONCLUSION: If confirmed in larger cohorts, the addition of tumor budding to K-RAS analysis may represent an effective approach for individualized patient management in the metastatic setting.