Management of advanced colorectal cancer, Part 1

Preliminary clinical study of personalized neoantigen vaccine therapy for microsatellite stability (MSS)-advanced colorectal cancer

Immunotherapy based on immune checkpoint inhibitors (ICIs) has provided revolutionary results in treating various cancers. However, its efficacy in colorectal cancer (CRC), especially in microsatellite stability-CRC, is limited. This study aimed to observe the efficacy of personalized neoantigen vaccine in treating MSS-CRC patients with recurrence or metastasis after surgery and chemotherapy. Candidate neoantigens were analyzed from whole-exome and RNA sequencing of tumor tissues. The safety and immune response were assessed through adverse events and ELISpot. The clinical response was evaluated by progression-free survival (PFS), imaging examination, clinical tumor marker detection, circulating tumor DNA (ctDNA) sequencing. Changes in health-related quality of life were measured by the FACT-C scale. A total of six MSS-CRC patients with recurrence or metastasis after surgery and chemotherapy were administered with personalized neoantigen vaccines. Neoantigen-specific immune response was observed in 66.67% of the vaccinated patients. Four patients remained progression-free up to the completion of clinical trial. They also had a significantly longer progression-free survival time than the other two patients without neoantigen-specific immune response (19 vs. 11 months). Changes in health-related quality of life improved for almost all patients after the vaccine treatment. Our results shown that personalized neoantigen vaccine therapy is likely to be a safe, feasible and effective strategy for MSS-CRC patients with postoperative recurrence or metastasis.

Regulation of Wnt receptor activity: Implications for therapeutic development in colon cancer

Hyperactivation of Wnt/β-catenin (canonical) signaling in colorectal cancers (CRCs) was identified in the 1990s. Most CRC patients have mutations in genes that encode components of the Wnt pathway. Inactivating mutations in the adenomatous polyposis coli (APC) gene, which encodes a protein necessary for β-catenin degradation, are by far the most prevalent. Other Wnt signaling components are mutated in a smaller proportion of CRCs; these include a FZD-specific ubiquitin E3 ligase known as ring finger protein 43 that removes FZDs from the cell membrane. Our understanding of the genetic and epigenetic landscape of CRC has grown exponentially because of contributions from high-throughput sequencing projects such as The Cancer Genome Atlas. Despite this, no Wnt modulators have been successfully developed for CRC-targeted therapies. In this review, we will focus on the Wnt receptor complex, and speculate on recent discoveries about ring finger protein 43regulating Wnt receptors in CRCs. We then review the current debate on a new APC-Wnt receptor interaction model with therapeutic implications.

Heme-Dependent ER Stress Apoptosis: A Mechanism for the Selective Toxicity of the Dihydroartemisinin, NSC735847, in Colorectal Cancer Cells

Colorectal cancer (CRC) is a leading cause of cancer death in the United States. Artemisinin derivatives, including the dihydroartemisinin (DHA) monomers, are widely used as clinical agents for the treatment of malaria. Numerous studies demonstrate that these molecules also display antineoplastic activity with minimal toxicity. Of interest, dimeric DHA molecules are more active than their monomeric counterparts. Our previous data showed that the DHA dimer, NSC735847, was a potent inducer of death in different cancer cell types. However, the mechanism of action and activity of NSC735847 in colon cancer cells was not explored. The present study investigated the anticancer activity of NSC735847 and four structurally similar analog in human tumorigenic (HT-29 and HCT-116) and non-tumorigenic (FHC) colon cell lines. NSC735847 was more cytotoxic toward tumorigenic than non-tumorigenic colonocytes. In addition, NSC735847 exhibited greater cytotoxicity and tumor selectivity than the NSC735847 derivatives. To gain insight into mechanisms of NSC735847 activity, the requirement for endoplasmic reticulum (ER) stress and oxidative stress was tested. The data show that ER stress played a key role in the cytotoxicity of NSC735847 while oxidative stress had little impact on cell fate. In addition, it was observed that the cytotoxic activity of NSC735847 required the presence of heme, but not iron. The activity of NSC735847 was then compared to clinically utilized CRC therapeutics. NSC735847 was cytotoxic toward colon tumor cells at lower concentrations than oxaliplatin (OX). In addition, cell death was achieved at lower concentrations in colon cancer cells that were co-treated with folinic acid (Fol), 5-FU (F), and NSC735847 (FolFNSC), than Fol, F, and OX (FolFOX). The selective activity of NSC735847 and its ability to induce cytotoxicity at low concentrations suggest that NSC735847 may be an alternative for oxaliplatin in the FolFOX regimen for patients who are unable to tolerate its adverse effects.

miR-361 enhances sensitivity to 5-fluorouracil by targeting the FOXM1-ABCC5/10 signaling pathway in colorectal cancer

Colorectal cancer (CRC) is one of most common malignancies worldwide. 5-fluorouracil (5-FU) is a mainstay of CRC treatment, particularly in patients with advanced stages of the disease; however, 5-FU-based chemotherapy is not always effective and may result in progression of the disease. The present study investigated several candidate microRNAs (miRs) in parental and 5-FU-resistant HCT116 and HT29 cells, and identified miR-361 as a novel regulator of chemosensitivity. Overexpression of miR-361 enhanced the 5-FU susceptibility of parental and resistant HCT116 and HT29 cells in vitro. Impaired colony formation capacity and increased cell apoptosis (as determined via flow cytometry) was observed in resistant HCT116 and HT29 cells. Furthermore, forkhead box M1 (FOXM1) was identified as a target gene of miR-361 using a dual-luciferase reporter assay, western blotting and reverse transcription-quantitative PCR. Additionally, FOXM1 knockdown improved the cytotoxicity of 5-FU in resistant CRC. ATP binding cassette subfamily C members 5 and 10 (ABCC5/10) were found to be downstream effectors of miR-361. In conclusion, miR-361 increased chemosensitivity, at least in part, via modulation of FOXM1-ABCC5/10. miR-361 may serve as a potential therapeutic target for patients with CRC.

A tannin compound from Sanguisorba officinalis blocks Wnt/β-catenin signaling pathway and induces apoptosis of colorectal cancer cells

BACKGROUND

Sanguisorba officinalis, a popular Chinese herb, called DiYu, has been shown to inhibit the growth of many human cancer cell lines, including colorectal cancer cells. The aims of this study were to discover the active compound and molecular mechanism of S. officinalis against Wnt/β-catenin signaling pathway and develop Wnt inhibitors from natural products as anti-colorectal cancer agents.

METHODS

1,4,6-Tri-O-galloyl-β-d-glucopyranose (TGG) was obtained by the preparative HPLC. The effect of DiYu on proliferation of NIH3T3 and HT29 was detected by MTT assay. Luciferase reporter assay was applied to investigate the activity of Wnt/β-catenin signaling in NIH3T3. The expression levels of mRNA and protein were detected by RT-PCR and western blot. Immunofluorescence assay was used to measure the level of β-catenin in cytoplasm and nucleus. Transcriptomic profiling study was performed to investigate the molecular mechanism of DiYu on the Wnt/β-catenin signaling pathway.

RESULTS

TGG significantly inhibited the Wnt/β-catenin signaling pathway, down-regulated the expression of β-catenin and Wnt target genes (Dkk1, c-Myc, FGF20, NKD1, Survivin), up-regulated the levels of cleaved caspase3, cleaved PARP and ratio of Bax/Bcl-2, which may explain the apoptosis of HT29.

CONCLUSIONS

Our study enhanced the discovery of the materials and elucidation of mechanisms that account for the anti-Wnt activity of natural inhibitor (DiYu) and identified the potential of TGG to be developed as anti-colorectal cancer drugs.

Alterations in intestinal microbiota of colorectal cancer patients receiving radical surgery combined with adjuvant CapeOx therapy

An intricate relationship exists and interactions occur between gut microbiota and colorectal cancer (CRC). Radical surgery combined with adjuvant chemotherapy (AC) serves as the mainstream therapeutic scheme for most CRC patients. The current research was conducted to assess the effect of surgery or chemotherapy on gut microbiota. Forty-three CRC patients who received radical surgery and AC were enrolled. Fecal samples were collected preoperatively, postoperatively, and after the first to fifth cycles of postoperative chemotherapy. The microbial community of each sample was analyzed using high throughput 16S rRNA amplicon sequencing. Compared with preoperative samples, fecal samples collected postoperatively exhibited a significant decrease of obligate anaerobes, tumor-related bacteria, and butyric acid-producing bacteria. However, a significant increase of some conditional pathogens was observed. In addition, the AC regimen (CapeOx) was found to alter intestinal microbiota dramatically. In particular, several changes were observed after chemotherapy including an increase of pathogenic bacteria, the "rebound effect" of chemotherapy-adapted bacteria, the shift of lactate-utilizing microbiota from Veillonella to Butyricimonas and Butyricicoccus, as well as the decrease of probiotics. Both radical surgery and CapeOx chemotherapy exert a non-negligible effect on the gut microbiota of CRC patients. Microbiota-based intervention may be beneficial for patients during postoperative clinical management.

Deguelin induces apoptosis in colorectal cancer cells by activating the p38 MAPK pathway

Objectives

Deguelin, a rotenoid extracted from Mundulea sericea (Leguminosae), exhibits antitumor effects on several types of human cancers. Due to the limited studies of deguelin on colorectal cancer (CRC), the present study was designed to investigate the antitumor effect of deguelin and to explore the underlying mechanism in CRC.

Materials and methods

Cell viability was assessed by the cell counting kit-8 (CCK-8) assay, and cell apoptosis was determined by the annexin v-propidium iodide staining using flow cytometry and Western blot in CRC cell lines after incubation with deguelin. The antitumor effect of deguelin was further evaluated in tumor xenograft models. Moreover, SB203580, a specific inhibitor of p38 MAPK, was used to confirm the involvement of p38 MAPK pathway in deguelin-induced apoptosis.

Results

Deguelin significantly inhibited cell proliferation and induced apoptosis in CRC cell lines (SW620 and RKO) in a time-dependent and dose-dependent manner. Western blot analysis also showed that the expression of proapoptotic proteins (cleaved caspase 3 and cleaved PARP) was upregulated, while that of antiapoptotic proteins (Bcl-2 and survivin) was downregulated after deguelin treatment in CRC cell lines. Moreover, oral administration of deguelin significantly suppressed tumor growth and induced apoptosis in subcutaneous xenograft mouse models without obvious toxicity. Additionally, Western blot revealed that deguelin-induced apoptosis might be regulated by the p38 MAPK pathway and inhibition of p38 MAPK could attenuate deguelin-induced proliferative inhibition and apoptosis in CRC cells.

Conclusion

Collectively, these results demonstrated that deguelin inhibited CRC cell growth by inducing apoptosis via activation of p38 MAPK pathway.

New Trends in the Therapeutic Approach to Metastatic Colorectal Cancer

Important developments in chemotherapy for metastatic colorectal cancer over the last years are reviewed, with an emphasis on the most recently published data from clinical trials. The systematic review of current literature was conducted involving Pubmed Central^® research and full articles were obtained and analyzed when appropriate. Fluorouracil still constitutes the backbone of metastatic colorectal cancer treatment; fluorouracil combination plus either irinotecan (FOLFIRI), oxaliplatin (FOLFOX) or capecitabine (CAPOX or XELOX) are chemotherapy protocols established as treatments producing similar outcomes. Actual treatment involves these chemotherapy protocols in combination with new molecular targeted drugs: bevacizumab and aflibercept (anti-vascular endothelial growth factor monoclonal antibody) and cetuximab and panitumumab (anti-epidermal growth factor receptor monoclonal antibody for patients with wild type KRAS) which confer significant survival benefits in select patients as first- or second-line therapies. The factors affecting the decisions for one treatment over other are related to the patient and toxicity drug. Finally, metastatic colorectal cancer patients progressing after all standard therapies (maintaining a good ECOG performance status) could be candidates for further therapies such as regorafenib and TAS-102. Regarding the future, promising therapies are under development for the metastatic colorectal cancer treatment and several agents are currently being evaluated in different clinical trials.

A look into centrosome abnormalities in colon cancer cells, how they arise and how they might be targeted therapeutically

Cancer cells have long been noted for alterations in centrosome structure, number, and function. Colorectal cancers are interesting in this regard since two frequently mutated genes, APC and CTNNB1 (β-catenin), encode proteins that directly interact with the centrosome and affect its ability to direct microtubule growth and establish cell polarity. Colorectal cancers also frequently display centrosome over-duplication and clustering. Efforts have been directed toward understanding how supernumerary centrosomes cluster and whether disrupting this clustering may be a way to induce aberrant/lethal mitoses of cancer cells. Given the important role of the centrosome in establishing spindle polarity and regulating some apoptotic signaling pathways, other approaches to centrosome targeting may be fruitful as well. Basic information on the nature and extent of centrosome defects in colorectal cancer, including why they over-duplicate and whether this over-duplication compensates for their functional defects, could provide a framework for the development of novel approaches for the therapeutic targeting of colorectal cancer.

HLA-G 3'UTR Polymorphisms Predict Drug-Induced G3-4 Toxicity Related to Folinic Acid/5-Fluorouracil/Oxaliplatin (FOLFOX4) Chemotherapy in Non-Metastatic Colorectal Cancer

Polymorphisms in drug-metabolizing enzymes might not completely explain inter-individual differences in toxicity profiles of patients with colorectal cancer (CRC) that receive folinic acid/5-fluorouracil/oxaliplatin (FOLFOX4). Recent data indicate that the immune system could contribute to FOLFOX4 outcomes. In light of the immune inhibitory nature of human leukocyte antigen-G (HLA-G), a non-classical major histocompatibility complex (MHC) class I molecule, we aimed to identify novel genomic markers of grades 3 and 4 (G3-4) toxicity related to FOLFOX4 therapy in patients with CRC. We retrospectively analyzed data for 144 patients with stages II-III CRC to identify HLA-G 3′ untranslated region (3′UTR) polymorphisms and related haplotypes and evaluate their impact on the risk of developing G3-4 toxicities (i.e., neutropenia, hematological/non-hematological toxicity, neurotoxicity) with logistic regression. The rs1610696-G/G polymorphism was associated with increased risk of G3-4 neutropenia (OR = 3.76, p = 0.015) and neurotoxicity (OR = 8.78, p = 0.016); rs371194629-Ins/Ins was associated with increased risk of neurotoxicity (OR = 5.49, p = 0.027). HLA-G 3′UTR-2, which contains rs1610696-G/G and rs371194629-Ins/Ins polymorphisms, was associated with increased risk of G3-4 neutropenia (OR = 3.92, p = 0.017) and neurotoxicity (OR = 11.29, p = 0.009). A bootstrap analysis confirmed the predictive value of rs1610696 and rs371194629, but the UTR-2 haplotype was validated only for neurotoxicity. This exploratory study identified new HLA-G 3′UTR polymorphisms/haplotypes as potential predictive markers of G3-4 toxicities in CRC.

Functional analysis of rare variants in mismatch repair proteins augments results from computation-based predictive methods

The cancer-predisposing Lynch Syndrome (LS) arises from germline mutations in DNA mismatch repair (MMR) genes, predominantly MLH1, MSH2, MSH6, and PMS2. A major challenge for clinical diagnosis of LS is the frequent identification of variants of uncertain significance (VUS) in these genes, as it is often difficult to determine variant pathogenicity, particularly for missense variants. Generic programs such as SIFT and PolyPhen-2, and MMR gene-specific programs such as PON-MMR and MAPP-MMR, are often used to predict deleterious or neutral effects of VUS in MMR genes. We evaluated the performance of multiple predictive programs in the context of functional biologic data for 15 VUS in MLH1, MSH2, and PMS2. Using cell line models, we characterized VUS predicted to range from neutral to pathogenic on mRNA and protein expression, basal cellular viability, viability following treatment with a panel of DNA-damaging agents, and functionality in DNA damage response (DDR) signaling, benchmarking to wild-type MMR proteins. Our results suggest that the MMR gene-specific classifiers do not always align with the experimental phenotypes related to DDR. Our study highlights the importance of complementary experimental and computational assessment to develop future predictors for the assessment of VUS.

Looking up: Recent advances in understanding and treating peritoneal carcinomatosis

Until recently, a diagnosis of peritoneal carcinomatosis was uniformly accompanied by a grim prognosis that was typically measured in weeks to months. Consequently, the management of carcinomatosis revolves largely around palliation of symptoms such as bowel obstruction, nausea, pain, fatigue, and cachexia. A prior lack of effective treatment options created the nihilistic view that currently exists and persists despite improvements in the efficacy of systemic therapy and the evolution of multimodality approaches including surgery and intraperitoneal chemotherapy. This article reviews the evolution and current state of treatment options for patients with peritoneal carcinomatosis. In addition, it highlights recent advances in understanding the molecular biology of carcinomatosis and the focus of current and future clinical trials. Finally, this article provides practical management options for the palliation of common complications of carcinomatosis. It is hoped that the reader will recognize that carcinomatosis is no longer an imminent death sentence and that through continued research and therapeutic innovation, clinicians can make an even greater impact on this form of metastatic cancer.

Trial watch - inhibiting PARP enzymes for anticancer therapy

Poly(ADP-ribose) polymerases (PARPs) are a members of family of enzymes that catalyze poly(ADP-ribosyl)ation (PARylation) and/or mono(ADP-ribosyl)ation (MARylation), two post-translational protein modifications involved in crucial cellular processes including (but not limited to) the DNA damage response (DDR). PARP1, the most abundant family member, is a nuclear protein that is activated upon sensing distinct types of DNA damage and contributes to their resolution by PARylating multiple DDR players. Recent evidence suggests that, along with DDR, activated PARP1 mediates a series of prosurvival and proapoptotic processes aimed at preserving genomic stability. Despite this potential oncosuppressive role, upregulation and/or overactivation of PARP1 or other PARP enzymes has been reported in a variety of human neoplasms. Over the last few decades, several pharmacologic inhibitors of PARP1 and PARP2 have been assessed in preclinical and clinical studies showing potent antineoplastic activity, particularly against homologous recombination (HR)-deficient ovarian and breast cancers. In this Trial Watch, we describe the impact of PARP enzymes and PARylation in cancer, discuss the mechanism of cancer cell killing by PARP1 inactivation, and summarize the results of recent clinical studies aimed at evaluating the safety and therapeutic profile of PARP inhibitors in cancer patients.

Combined Effects of Muricid Extract and 5-Fluorouracil on Intestinal Toxicity in Rats

Chemotherapy drugs, such as 5-fluorouracil (5FU), are the standard approach for cancer and are associated with several peripheral toxicities. We previously demonstrated that Muricidae marine molluscs exhibit chemopreventive properties. This study investigated the combined effect of muricid extract derived from Dicathais orbita, with 5FU, on intestinal toxicity in rats. Groups of rats were orally gavaged water, muricid extract, or sunflower oil, with or without 5FU (150 mg/kg). Metabolic data was collected daily and small intestinal brush border enzyme activity was measured by sucrose breath test (SBT). Blood was collected by cardiac puncture for whole blood analysis. Intestinal biopsies were taken for histopathology. Neutrophil activity was measured by myeloperoxidase activity. No additional toxicity effects were observed in rats receiving the combination of 5FU and muricid extract compared to 5FU alone, as indicated by SBT, histopathology, and myeloperoxidase activity. Intestinal integrity was protected from 5FU-induced damage in the sunflower oil vehicle group, compared to controls, as measured by SBT, villus height, and crypt depth. We concluded that combination of muricid extract and 5FU did not confer any additional intestinal toxicity, further supporting its potential as a chemopreventive food product. In this model system, sunflower oil partially protected against 5FU-induced intestinal toxicity.

Meta-analysis comparing the safety and efficacy of metastatic colorectal cancer treatment regimens, capecitabine plus irinotecan (CAPIRI) and 5-fluorouracil/leucovorin plus irinotecan (FOLFIRI)

The relative efficacy and safety of first-line metastatic colorectal cancer (mCRC) treatment regimens, capecitabine with irinotecan (CAPIRI) and 5-fluorouracil/leucovorin plus irinotecan (FOLFIRI), are not well defined. We identified and subsequently examined seven independent, randomized controlled clinical trials, performing a meta-analysis to compare these two treatment regimens. Using Medline, EMBASE, Cochrane Library (CENTRAL), and the American Society of Clinical Oncology Annual Meeting to search available literature until February 2014, we identified seven studies comparing safety and efficacy of CAPIRI and FOLFIRI in mCRC patients. These studies were pooled and evaluated for rates of progression-free survival (PFS), objective response rate (ORR), overall survival (OS), and diarrhea. CAPIRI and FOLFIRI demonstrated similar efficacy outcomes, though CAPIRI was associated with a higher incidence of diarrhea. CAPIRI and FOLFIRI are equally effective options for first-line treatment of mCRC.

Monofunctional platinum(II) complexes with potent tumor cell growth inhibitory activity: the effect of a hydrogen-bond donor/acceptor N-heterocyclic ligand

In this paper we investigate the possibility of further increase the role of the N-donor aromatic base in antitumor Hollis-type compounds by conferring the possibility to act as a hydrogen-bond donor/acceptor. Therefore, we synthesized the Pt(II) complex cis-[PtCl(NH3 )2 (naph)]NO3 (1) containing the 1,8-naphthyridine (naph) ligand. The naphthyridine ligand is generally monodentate, and the second nitrogen atom can act as H-bond donor/acceptor depending upon its protonation state. The possibility of forming such an H-bond could be crucial in the interaction of the drug with DNA or proteins. Apart from the synthesis of the compound, in this study we evaluated its in vitro antitumor activity in a wide panel of tumor cell lines, also including cells selected for their sensitivity/resistance to oxaliplatin, which was compared with that of previously reported complex 2 ([PtI(2,9-dimethyl-1,10-phenanthroline)(1-methyl-cytosine)]I) and oxaliplatin and cisplatin as reference compounds. The cytotoxicity data were correlated with the cellular uptake and the DNA platination levels. Finally, the reactivity of 1 towards guanosine 5'-monophosphate (5'-GMP) and glutathione was investigated to provide insights into its mechanism of action.

Communicating bodily changes: physicians' ways of enabling patient understanding in gastrointestinal cancer consultations

OBJECTIVE

To explore how physicians communicatively enable patients' understanding of bodily changes in gastrointestinal cancer care consultations.

METHOD

Two datasets were used. The first consisted of transcribed video-recorded palliative care consultations with three oncologists and six patients diagnosed with advanced gastrointestinal cancer, in the context of outpatient palliative care. The second dataset was audio-recorded transcriptions from diagnostic consultations with six surgeons and seven patients diagnosed with colorectal cancer, in the context of cancer surgery. An inductively driven and iterative analysis of interaction was performed, guided by Wetherell et al. (2001).

RESULTS

Two overarching communicative strategies were identified: (1) "visualizing strategies," with the dimensions: visible strategies (visualizing with what you actually or potentially can see), sensory strategies (visualizing with what is possible to feel), and imaginative strategies; and (2) "contrasting strategies," with the dimensions: contrasting subjective experiences and contrasting between the patient and other people.

SIGNIFICANCE OF RESULTS

The visualizing and contrasting communicative strategies form parts of physicians' tacit and experience-based knowledge. The strategies employed by physicians reveal clear potentials to enable patients' understanding and sense making of bodily changes. However, these strategies need to be explicated and problematized as parts of both consultation practice and basic medical education. By means of increased awareness, physicians can more easily identify turning points in patients' levels of understanding, thereby enriching ordinary medical consultations with reflected pedagogical strategies and skills in how to dialogue in a person-centered manner.

Chemopreventive drugs: Mechanisms via inhibition of cancer stem cells in colorectal cancer

Recent epidemiological studies, basic research and clinical trials on colorectal cancer (CRC) prevention have helped identify candidates for effective chemopreventive drugs. However, because of the conflicting results of clinical trials or side effects, the effective use of chemopreventive drugs has not been generalized, except for patients with a high-risk for developing hereditary CRC. Advances in genetic and molecular technologies have highlighted the greater complexity of carcinogenesis, especially the heterogeneity of tumors. We need to target cells and processes that are critical to carcinogenesis for chemoprevention and treatment of advanced cancer. Recent research has shown that intestinal stem cells may serve an important role in tumor initiation and formation of cancer stem cells. Moreover, studies have shown that the tumor microenvironment may play additional roles in dedifferentiation, to enable tumor cells to take on stem cell features and promote the formation of tumorigenic stem cells. Therefore, early tumorigenic changes of stem cells and signals for dedifferentiation may be good targets for chemoprevention. In this review, I focus on cancer stem cells in colorectal carcinogenesis and the effect of major chemopreventive drugs on stem cell-related pathways.

Anti-angiogenic therapies for metastatic colorectal cancer: Current and future perspectives

Colorectal cancer (CRC) is the fourth most commonly diagnosed cancer and the second leading cause of cancer death in both men and women in the United States, with about 142820 new cases and 50830 deaths expected in 2013. Metastatic disease (mCRC) remains a challenge for oncologists worldwide due to its potential comorbidities. Recently, chemotherapy regimens containing 5-fluorouracil, leucovorin, oxaliplatin and irinotecan combinations are a standard of care in the metastatic disease. Currently, biological therapies involving vascular endothelial growth factor and epidermal growth factor receptor pathways, such as bevacizumab and cetuximab, have emerged as good option for improving mCRC patient survival. Now, aflibercept plus standard chemotherapy has also been approved in second line regimen for mCRC patients. Our review will discuss novel biological drugs and their indications for mCRC patients and will bring future perspectives in this regard.

Molecularly targeted drugs for metastatic colorectal cancer

The survival rate of patients with metastatic colorectal cancer (mCRC) has significantly improved with applications of molecularly targeted drugs, such as bevacizumab, and led to a substantial improvement in the overall survival rate. These drugs are capable of specifically targeting the inherent abnormal pathways in cancer cells, which are potentially less toxic than traditional nonselective chemotherapeutics. In this review, the recent clinical information about molecularly targeted therapy for mCRC is summarized, with specific focus on several of the US Food and Drug Administration-approved molecularly targeted drugs for the treatment of mCRC in the clinic. Progression-free and overall survival in patients with mCRC was improved greatly by the addition of bevacizumab and/or cetuximab to standard chemotherapy, in either first- or second-line treatment. Aflibercept has been used in combination with folinic acid (leucovorin)-fluorouracil-irinotecan (FOLFIRI) chemotherapy in mCRC patients and among patients with mCRC with wild-type KRAS, the outcomes were significantly improved by panitumumab in combination with folinic acid (leucovorin)-fluorouracil-oxaliplatin (FOLFOX) or FOLFIRI. Because of the new preliminary studies, it has been recommended that regorafenib be used with FOLFOX or FOLFIRI as first- or second-line treatment of mCRC chemotherapy. In summary, an era of new opportunities has been opened for treatment of mCRC and/or other malignancies, resulting from the discovery of new selective targeting drugs.

Novel drug discovery opportunities for colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is a leading cause of cancer mortality worldwide, with > 1.2 million new cases and > 600,000 deaths per year. This complex disease is driven by multiple genetic lesions, commonly dysregulated signaling pathways, and aberrant activity of developmental programs such as Notch and Wnt. While emerging therapies such as EGFR inhibitors are improving treatment regimens, recent findings elucidating the role of cancer stem cells provide insights into opportunities for novel therapeutic intervention.

AREAS COVERED

This review provides a background on CRC statistics, colon anatomy and CRC pathobiology, CRC genetics and current and emerging therapies. Furthermore, the article discusses the role of developmental signaling pathways governing self-renewal biology as potential points for therapeutic intervention.

EXPERT OPINION

Despite recent advances including the introduction of targeted therapeutics, prognosis for advanced CRC patients remains bleak, reinforcing the need for novel therapeutic intervention. Developmental pathways such as Notch and Wnt provide opportunities to address this urgent need, and preclinical evidence supports targeting these pathways in CRC. Progress has been made toward this end, and while challenges persist, an increasing number of preclinical findings show promise.