Activating KRAS mutations and overexpression of epidermal growth factor receptor as independent predictors in metastatic colorectal cancer patients treated with cetuximab

Signalling and molecular pathways, overexpressed receptors of colorectal cancer and effective therapeutic targeting using biogenic silver nanoparticles

Increasing morbidity and mortality in CRC is a potential threat to human health. The major challenges for better treatment outcomes are the heterogeneity of CRC cases, complicated molecular pathway cross-talks, the influence of gut dysbiosis in CRC, and the lack of multimodal target-specific drug delivery. The overexpression of many receptors in CRC cells may pave the path for targeting them with multiple ligands. The design of a more target-specific drug-delivery device with multiple ligand-functionalized, green-synthesized silver nanoparticles is highly promising and may also deliver other approved chemotherapeutic agents. This review presents the various aspects of colorectal cancer and over-expressed receptors that can be targeted with appropriate ligands to enhance the specific drug delivery potency of green synthesised silver nanoparticles. This review aims to broaden further research into this multi-ligand functionalised, safer and effective silver nano drug delivery system.

EGFR is a potential therapeutic target for highly glycosylated and aggressive pancreatic neuroendocrine neoplasms

pNENs are relative indolent tumors with heterogeneous clinical presentation at diagnosis. It is important to establish aggressive subgroups of pNENs and identify potential therapeutic targets. Patients with pNEN (322 cases) were included to examine the association between glycosylation biomarkers and clinical/pathological traits. The molecular and metabolic features stratified by glycosylation status were assessed by RNA-seq/whole exome sequencing and immunohistochemistry. A considerable proportion of patients had elevated glycosylation biomarkers (carbohydrate antigen [CA] 19-9, 11.9%; CA125, 7.5%; carcinoembryonic antigen [CEA], 12.8%). CA19-9 (hazard ratio [HR] = 2.26, P = .019), CA125 (HR = 3.79, P = .004) and CEA (HR = 3.16, P = .002) were each independent prognostic variables for overall survival. High glycosylation group, defined as pNENs with elevated level of circulating CA19-9, CA125 or CEA, accounted for 23.4% of all pNENs. High glycosylation (HR = 3.14, P = .001) was an independent prognostic variable for overall survival and correlated with G3 grade (P < .001), poor differentiation (P = .001), perineural invasion (P = .004) and distant metastasis (P < .001). Epidermal growth factor receptor (EGFR) was enriched in high glycosylation pNENs using RNA-seq. EGFR was expressed in 21.2% of pNENs using immunohistochemistry and associated with poor overall survival (P = .020). A clinical trial focusing on EGFR expressed pNENs was initiated (NCT05316480). Thus, pNEN with aberrant glycosylation correlates with a dismal outcome and suggests potential therapeutic target of EGFR.

EGFR, HER2, and HER3 protein expression in paired primary tumor and lymph node metastasis of colorectal cancer

Due to the difficulty in sampling of metastatic tumors, patient selection is commonly based on results of primary tumor samples when metastatic samples are not available. However, due to tumor heterogeneity, metastatic tumors may be different from primary tumors in their phenotypes. The aim of this study was to investigate the expression of EGFR, HER2, and HER3 between primary and lymph node metastatic lesions of colorectal cancer. Paired primary tumors and lymph node metastases from 79 patients with colorectal cancer were retrospectively collected and analyzed for EGFR, HER2, and HER3 expression. High EGFR, HER2, and HER3 expression (2+ and 3+) was found in 64.2%, 66.0%, and 85.0% of primary tumors, and 56.8%, 46.0%, and 76.0% of lymph node metastases, respectively. Correlation rates between primary and metastatic lesions were 67.1%, 63.3%, and 74.7% for EGFR, HER2, and HER3, respectively. Stage IV tumors (with distant metastasis) had higher correlation rates of HER2 expression compared to stage III tumors (without distant metastasis) (P = 0.050). Moderate correlation rates in EGFR, HER2, and HER3 expression were observed between primary and metastatic lesions of colorectal cancer. Tumor stage or existence of distant metastasis could serve as potential predictive markers for the correlation of HER2 expression between primary tumors and lymph node metastases of colorectal cancer.

Complete Response With Cetuximab-Based Treatment of Metastatic Colorectal Cancers: Two Case Reports and Literature Review

Metastases typically develop before diagnosis and during the treatment of colorectal cancers, while patients with metastatic colorectal cancers (mCRCs) currently have a poor prognosis. In terms of surgical approaches, adjuvant therapies, and targeted therapies, the treatment of mCRCs has had numerous recent advances. As a targeted agent widely used in mCRCs, cetuximab-based treatment is still under dispute due to its side effects and unstable effect. We present two mCRC cases treated with cetuximab-based therapy, of which two patients achieved complete response and without recurrence for over 22 and 84 months, respectively. To better understand the drug usage, we also reviewed the recent achievements and usage precautions of cetuximab in mCRCs. Present and many previous observations support that cetuximab might be a referred drug in the first-line chemotherapy of mCRCs with wild-type RAS and BRAF and proficient mismatch repair.

Resistance to anti-EGFR therapies in metastatic colorectal cancer: underlying mechanisms and reversal strategies

Cetuximab and panitumumab are monoclonal antibodies (mAbs) against epidermal growth factor receptor (EGFR) that are effective agents for metastatic colorectal cancer (mCRC). Cetuximab can prolong survival by 8.2 months in RAS wild-type (WT) mCRC patients. Unfortunately, resistance to targeted therapy impairs clinical use and efficiency. The mechanisms of resistance refer to intrinsic and extrinsic alterations of tumours. Multiple therapeutic strategies have been investigated extensively to overcome resistance to anti-EGFR mAbs. The intrinsic mechanisms include EGFR ligand overexpression, EGFR alteration, RAS/RAF/PI3K gene mutations, ERBB2/MET/IGF-1R activation, metabolic remodelling, microsatellite instability and autophagy. For intrinsic mechanisms, therapies mainly cover the following: new EGFR-targeted inhibitors, a combination of multitargeted inhibitors, and metabolic regulators. In addition, new cytotoxic drugs and small molecule compounds increase the efficiency of cetuximab. Extrinsic alterations mainly disrupt the tumour microenvironment, specifically immune cells, cancer-associated fibroblasts (CAFs) and angiogenesis. The directions include the modification or activation of immune cells and suppression of CAFs and anti-VEGFR agents. In this review, we focus on the mechanisms of resistance to anti-EGFR monoclonal antibodies (anti-EGFR mAbs) and discuss diverse approaches to reverse resistance to this therapy in hopes of identifying more mCRC treatment possibilities.

Design, Synthesis, Characterization, and Crystal Structure Studies of Nrf2 Modulators for Inhibiting Cancer Cell Growth In Vitro and In Vivo

Nrf2 is one of the important therapeutic targets studied extensively in several cancers including the carcinomas of the colon and rectum. However, to date, not many Nrf2 inhibitors showed promising results for retarding the growth of colorectal cancers (CRCs). Therefore, in this study, first, we have demonstrated the therapeutic effect of siRNA-mediated downmodulation of Nrf2 on the proliferation rate of CRC cell lines. Next, we have designed, synthesized, characterized, and determined the crystal structures for a series of tetrahydrocarbazoles (THCs) and assessed their potential to modulate the activity of Nrf2 target gene NAD(P)H:quinone oxidoreductase (NQO1) activity by treating colorectal carcinoma cell line HCT-116. Later, the cytotoxic potential of compounds was assessed against cell lines expressing varying amounts of Nrf2, viz., breast cancer cell lines MDA-MB-231 and T47D (low functionally active Nrf2), HCT-116 (moderately active Nrf2), and lung cancer cell line A549 (highly active Nrf2), and the lead compound 5b was tested for its effect on cell cycle progression in vitro and for retarding the growth of Ehrlich ascites carcinomas (EACs) in mice. Data from our study demonstrated that among various compounds 5b exhibited better therapeutic index and retarded the growth of EAC cells in mice. Therefore, compound 5b is recommended for further development to target cancers.

Epidermal Growth Factor Receptor: Key to Selective Intracellular Delivery

Epidermal growth factor receptor (EGFR) is an integral surface protein mediating cellular response to a number of growth factors. Its overexpression and increased activation due to mutations is one of the most common traits of many types of cancer. Development and clinical use of the agents, which block EGFR activation, became a prime example of the personalized targeted medicine. However, despite the obvious success in this area, cancer cure remains unattainable in most cases. Because of that, as well as the result of the search for possible ways to overcome the difficulties of treatment, a huge number of new treatment methods relying on the use of EGFR overexpression and its changes to destroy cancer cells. Modern data on the structure, functioning, and intracellular transport of EGFR, its natural ligands, as well as signaling cascades triggered by the EGFR activation, peculiarities of the EGFR expression and activation in oncological disorders, as well as applied therapeutic approaches aimed at blocking EGFR signaling pathway are summarized and analyzed in this review. Approaches to the targeted delivery of various chemotherapeutic agents, radionuclides, immunotoxins, photosensitizers, as well as the prospects for gene therapy aimed at cancer cells with EGFR overexpression are reviewed in detail. It should be noted that increasing attention is being paid nowadays to the development of multifunctional systems, either carrying several different active agents, or possessing several environment-dependent transport functions. Potentials of the systems based on receptor-mediated endocytosis of EGFR and their possible advantages and limitations are discussed.

Proteomic profiling reveals a signature for optimizing prognostic prediction in Colon Cancer

Previous studies developed prognostic signatures largely depended on transcriptome profiles. The purpose of our present study was to develop a proteomic signature to optimize the evaluation of prognosis of colon cancer patients. The proteomic data of colon cancer patient cohorts were downloaded from The Cancer Proteome Atlas (TCPA). Patients were randomized 3:2 to train set and internal validation set. Univariate Cox regression and lasso Cox regression analysis were performed to identify the prognostic proteins. A four-protein signature was developed to divide patients into a high-risk group and low-risk group with significantly different survival outcomes in both train set and internal validation set. Time-dependent receiver-operating characteristic at 1 year demonstrated that the proteomic signature presented more prognostic accuracy [area under curve (AUC = 0.704)] than the American Joint Commission on Cancer tumor-node-metastasis (AJCC-TNM) staging system (AUC = 0.681) in entire set. In conclusion, we developed a proteomic signature which can improve prognostic accuracy of patients with colon cancer and optimize the therapeutic and follow-up strategies.

Neoadjuvant therapy of cetuximab combined with chemoradiotherapy in rectal cancer: A single-arm meta-analysis of noncomparative clinical studies and randomized controlled trials

OBJECTIVE

Preoperative chemoradiotherapy combined with radical resection has reduced local recurrence rates in rectal cancer. Cetuximab shows improvement in rectal cancer treatment. But the role for neoadjuvant therapy of cetuximab combined with chenmoradiotherapy in rectal cancer remains unclear. The present study aimed to use meta-analytical techniques to assess its benefit and risk.

MATERIALS AND METHODS

We searched PubMed, the Cochrane Library, Embase to identify the correlational non-comparative clinical studies and randomized controlled trials (RCTs). The primary endpoints of interest were pathological complete response (pCR), complete response (CR), partial response (PR), stable disease, progressive disease (PD), R0-resection, R1-resection, and R2-resection. The secondary included any grade of toxicity.

RESULTS

Eleven investigations (9 noncomparative open-label cohort studies and 2 randomized controlled trials) involving 550 patients were ultimately included. The pooled estimates of pCR was 10% (95% confidence interval [CI]: 7%-13%, I2 = 55.9%). Simultaneously, only a small amount of patients achieved CR (11%, 95% CI: 7%-15%, I2 = 44.0%), which was consistent with pCR. Besides, R0 resection (93%, 95% CI: 90%-96%, I2 = 16.5%) seemed to be increased but need further exploration. The safety was also calculated, and most of the toxicities were moderate.

CONCLUSION

Neoadjuvant therapy of cetuximab combined with chemoradiotherapy could not improve pCR. The raise of R0-resection rate needed to be verified by more high-quality and well-designed RCTs. Meanwhile, the morbidity of toxicity was relatively mild and acceptable.

The effectiveness of cetuximab and panitumumab when combined with FOLFIRI in second-line treatment of KRAS wild type metastatic colorectal cancers. Single centre experience

Panitumumab and cetuximab are monoclonal antibodies known to be effective in metastatic colorectal cancer (mCRC). Although the survival benefits when combined with chemotherapy have been determined, there are no studies comparing the two agents with chemotherapy in the second-line treatment. In this study, we aimed to compare the efficacy of cetuximab vs panitumumab in patients who previously received chemotherapy. Who progressed after first-line treatment for K-ras wild type mCRC were analyzed. The efficacy of cetuximab vs panitumumab on overall survival (OS) and progression-free survival (PFS) when combined with FOLFIRI regimen was compared retrospectively. Median PFS was 6.9 months in the cetuximab group and 4.7 months in the panitumumab group. Median OS cetuximab and panitumumab groups were 18.4 and 12.2 months, respectively. In the second-line treatment of K-ras wild type mCRC, both PFS and OS were found to be longer in patients receiving cetuximab than in patients receiving panitumumab, but no statistically significant difference was found.

Precision Approaches in the Management of Colorectal Cancer: Current Evidence and Latest Advancements Towards Individualizing the Treatment

The genetic and molecular underpinnings of metastatic colorectal cancer have been studied for decades, and the applicability of these findings in clinical decision making continues to evolve. Advancements in translating molecular studies have provided a basis for tailoring chemotherapeutic regimens in metastatic colorectal cancer (mCRC) treatment, which have informed multiple practice guidelines. Various genetic and molecular pathways have been identified as clinically significant in the pathogenesis of metastatic colorectal cancer. These include rat sarcoma (RAS), epithelial growth factor receptor (EGFR), vascular endothelial growth factor VEGF, microsatellite instability, mismatch repair, and v-raf murine sarcoma viral oncogene homolog b1 (BRAF) with established clinical implications. RAS mutations and deficiencies in the mismatch repair pathway guide decisions regarding the administration of anti-EGFR-based therapies and immunotherapy, respectively. Furthermore, there are several emerging pathways and therapeutic modalities that have not entered mainstream use in mCRC treatment and are ripe for further investigation. The well-established data in the arena of targeted therapies provide evidence-based support for the use or avoidance of various therapeutic regimens in mCRC treatment, while the emerging pathways and platforms offer a glimpse into the future of transforming a precision approach into a personalized treatment.

Effect of KRAS and NRAS mutations on the prognosis of patients with synchronous metastatic colorectal cancer presenting with liver-only and lung-only metastases

It has been reported that 20-25% of patients with colorectal cancer (CRC) have metastases at the time of diagnosis. Liver and lung are the most common metastatic sites. The aim of the present study was to investigate the association of KRAS and NRAS mutations with clinicopathological features and prognosis of patients with initial liver-metastasis only (LiM-only) or lung-metastasis only (LuM-only) metastatic CRC (mCRC). Overall, 166 patients with CRC with initial LiM-only (n=124) and LuM-only (n=42) were retrospectively analyzed from January 2014 to December 2017. The median follow-up time was 19.2 months (1.0-57.1 months). Patient characteristics at diagnosis were collected. Genomic DNA was isolated from frozen primary CRC tissues for targeting KRAS and NRAS. Patients with LuM-only were significantly older compared with those with LiM-only (65.5 vs. 61.5 years; P=0.05). There was no significant differences between the LiM-only and LuM-only groups in terms of sex, location of the primary tumor, serum carcinoembryonic antigen level, histological grade and RAS mutation status. KRAS mutations were detected in 43 (41.0%) patients with LiM-only and 13 (35.1%) patients with LuM-only. The overall survival time (OS) of LuM-only was more favorable compared with that of patients with LiM-only (44.5 vs. 24.7 months); however, there was no significant difference (P=0.095). The progression-free survival (PFS) and OS in the RAS wild-type group were significantly improved compared with the RAS mutant cohorts (P=0.004 and P=0.031, respectively) in the LiM-only group. In patients with stage IV CRC, those with synchronous LiM-only mCRC had a higher incidence of metastasis but a less favorable PFS and OS compared with patients with LuM-only. RAS mutation status exhibited a significant association with the survival outcome in patients with LiM-only mCRC.

Metastatic Colorectal Cancer: Prognostic and Predictive Factors

Colorectal cancer represents the third most frequently occurring cancer worldwide. In the last decade, the survival of patients affected by metastatic colorectal cancer (mCRC) has improved through the introduction of biological drugs. However, in this new and dynamic therapeutic context, research about prognostic and predictive factors is important to guide the oncologists to effective therapies as well as to improve the understanding of colorectal cancer biology. Their identification is an intensive area of research and our future goal will be to depict tumour-specific "molecular signatures" in order to predict the clinical course of the disease and the best treatments. In this report, we describe clinical, pathological and molecular biomarkers that can play a role as prognostic or predictive factors in mCRC.

Oncologic Outcomes in Metastatic Colorectal Cancer with Regorafenib with FOLFIRI as a Third- or Fourth-Line Setting

BACKGROUND

To evaluate the efficacy and toxicities of regorafenib plus irinotecan, dose-escalated on the basis of uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) genotyping, in previously heavily treated metastatic colorectal cancer (mCRC) and the prognostic values of EGFR expression, KRAS mutations, and tumor sidedness.

METHODS

Forty-one patients with mCRC with disease progression after treatment with fluoropyrimidines, oxaliplatin, irinotecan, anti-VEGF, and anti-EGFR MoAbs were subjected to UGT1A1 genotyping and received regorafenib combined with FOLFIRI with dose-escalated irinotecan.

RESULTS

The median follow-up period was 10.0 months (1.3-23.5 months). The overall disease control rate was 58.5%, whereas the median progression-free survival (PFS) and overall survival (OS) were 6.0 months and 12.0 months, respectively. KRAS mutations were significantly associated with positive EGFR expression (P = .026). KRAS mutations significantly correlated with a shorter OS than KRAS wild-type (6.0 vs. 14.4 months, P = .014) but had no significant association with PFS. Positive EGFR expression had an inverse correlation with PFS (2.5 vs. 14.0 months, P = .039) and OS (9.6 vs. 19.7 months, P = .044). Moreover, left-sided tumors associated with superior PFS (2.0 vs. 7.0 months, P < .0001) and OS (4.0 vs. 13.0 months, P < .0001), and tumor sidedness was an independent prognostic factor by the multivariate analysis.

CONCLUSION

Regorafenib and FOLFIRI concomitant therapy with dose-escalated irinotecan seemed to be potentially practicable with satisfactory oncological results. KRAS mutations and EGFR expression might be predictors of poor oncological outcomes; however, left-sided mCRCs would be more beneficial for concomitant regorafenib and FOLFIRI therapy.

Unresectable metastatic colorectal cancer patient cured with cetuximab-based chemotherapy: a case report with new molecular insights

Here we report the case of a 20-year-old patient who was diagnosed in 2002 with a metastatic colorectal cancer (CRC). He achieved a complete response under cetuximab-based therapy and remains without disease recurrence until now while chemotherapy was discontinued in 2009. The tumor exhibited high level of epidermal growth factor receptor (EGFR) amplification, no mutation in KRAS, NRAS or BRAF genes and a microsatellite-stable (MSS) phenotype. Intriguingly this young patient was carrying a monoallelic germline mutation of MUTYH that was associated with an inactivation of the second allele by loss of heterozygosity on tumor DNA. Moreover, this mutation was associated with a specific mutational signature on tumor level characterized by C > A single base substitutions and a higher mutational load than usually observed in MSS neoplasms. This case report paves the way for further researches on MUTYH-associated cancers' sensitivity to anticancer therapies.

Detection of PIK3CA Mutations in Plasma DNA of Colorectal Cancer Patients by an Ultra-Sensitive PNA-Mediated PCR

BACKGROUND

Mutant Phosphatidylinositol-4, 5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) has been shown to be associated with the occurrence, development and prognosis in colorectal cancer (CRC). However, its detection has been limited because of complicated procedures and the low sensitivity of the present approaches.

METHODS

We established an ultra-sensitive peptide nucleic acid-mediated polymerase chain reaction (PNA-PCR) assay to detect PIK3CA gene mutation in exon 9 and exon 20 with cell-free DNA (cfDNA). Using this technology, we detected the mutation status of PIK3CA in 128 colorectal cancer patients. 6 CRC patients receiving targeted therapy were chosen at random to undergo continuous PIK3CA mutation detection.

RESULTS

The results showed that the sensitivity of PNA-PCR clamping method was 0.1% for the exon 9 and 0.2% for the exon 20 variant alleles. When the PIK3CA mutation status was determined by PNA-PCR plus sequencing, 38.3% (49/128) of CRC carried at least one mutation, either E545Kor H1047R. The clinic-pathological parameters of age (p = 0.358), gender (p = 0.622), disease stage (p = 0.353) and disease location (p = 0.307) were not associated with the PIK3CA mutation. In the continuous monitoring study, we found that the gene status was associated with the effect of treatment. Furthermore, when the PIK3CA variant was determined by only the PNA-PCR method, there was a good linear relationship between ΔCp values and the proportion of variant DNA. The accuracy of PNA-PCR was 93.75 and 92.27% respectively when the cut-off values of ΔCp at 9.0 and 8.0 were set for determining the E545K and H1047R mutations.

CONCLUSIONS

A simple, noninvasive, ultra-sensitive PNA-PCR technology was developed and was especially suitable for the dynamic detection of PIK3CA variants using cfDNA.

The prognostic efficacy of cell-free DNA hypermethylation in colorectal cancer

Epigenetic alterations in colorectal cancer (CRC) cause important differences in the underlying tumor biology and aggressiveness. DNA hypermethylation is central for the development of CRC but the prognostic impact remains elusive. We aimed to assess the association between cell-free hypermethylated DNA and stage and survival in colorectal cancer (CRC). We analyzed pre-treatment plasma samples from 193 patients with CRC. Thirty gene-promoter regions were analyzed using methylation specific PCR. We compared the median number (range) of hypermethylated promoter regions with CRC stage, and constructed a multivariable Cox-regression model adjusted for stage, to evaluate the added prognostic information. The median number of hypermethylated promoter regions was nine (0-28) in patients with distant metastasis compared to five (0-19) in patients without metastatic disease (p < 0.0001). The majority of the hypermethylated promoter regions inferred a poor prognosis. Cox-regression analysis adjusted for patient age, sex, pre-treatment CEA-levels, and disease stage, showed that RARB (HR = 1.99, 95% CI [1.07, 3.72]) and RASSF1A (HR = 3.35, 95% CI [1.76, 6.38]) hypermethylation inferred a significant effect on survival. The risk of metastasis increase with the number of cell-free hypermethylated promoter regions. The presence of RARB and RASSF1A hypermethylation indicated aggressive disease, regardless of stage at the time of diagnosis.

KRAS biomarker testing disparities in colorectal cancer patients in New Mexico

Introduction

American Society of Clinical Oncology (ASCO) guidelines recommend that all patients with metastatic colorectal cancer (mCRC) receive KRAS testing to guide anti-EGFR monoclonal antibody treatment. The aim of this study was to assess for disparities in KRAS testing and mutational status.

Methods

The New Mexico Tumor Registry (NMTR), a population-based cancer registry participating in the National Cancer Institute's Surveillance, Epidemiology and End Results program, was queried to identify all incident cases of CRC diagnosed among New Mexico residents from 2010 to 2013.

Results

Six hundred thirty-seven patients were diagnosed with mCRC from 2010-2013. As expected, KRAS testing in Stage 4 patients presented the highest frequency (38.4%), though testing in stage 3 (8.5%), stage 2 (3.4%) and stage 1 (1.2%) was also observed. In those with metastatic disease, younger patients (≤ 64 years) were more likely to have had testing than patients 65 years and older (p < 0.0001). Patients residing in urban areas received KRAS testing more often than patients living in rural areas (p = 0.019). No significant racial/ethnic disparities were observed (p = 0.66). No significant differences were seen by year of testing.

Conclusion

Age and geographic disparities exist in the rates of KRAS testing, while sex, race/ethnicity and the year tested were not significantly associated with testing. Further study is required to assess the reasons for these disparities and continued suboptimal adherence to current ASCO KRAS testing guidelines.

Reduced-intensity FOLFOXIRI in Treating Refractory Metastatic Colorectal Cancer: A Pilot Study

OBJECTIVES

To report on the efficacy and safety of reduced-intensity FOLFOXIRI (RI-FOLFOXIRI) as salvage chemotherapy for patients with refractory metastatic colorectal cancer (mCRC).

METHODS

From October 2009 to March 2014, a total of 45 patients with refractory mCRC received RI-FOLFOXIRI as salvage chemotherapy. The initial dose of RI-FOLFOXIRI was 85% of the dose last used for each drug. All patients received a 2-hour infusion of folinate, followed by a bolus of 5-fluorouracil, and then 2400 to 3000 mg/m for 46 hours; in addition, patients were either administered irinotecan on day 1 followed by oxaliplatin on day 3 (group A), oxaliplatin on day 1 followed by irinotecan on day 3 (group B), or irinotecan and oxaliplatin on day 1 (group C).

RESULTS

Seven patients (15.6%) showed a partial response, and 15 patients (33.3%) had stable disease. The median progression-free and overall survival durations were 3.9 and 7.6 months, respectively. Patients who had wild-type K-RAS showed a longer overall survival duration (8.5 vs. 7.0 mo; P=0.04) but no difference in progression-free survival durations (4.4 vs. 3.4 mo; P=0.20) compared with patients with mutant K-RAS. The most common adverse events were neutropenia (28.9%) and diarrhea (26.7%).

CONCLUSIONS

RI-FOLFOXIRI as salvage chemotherapy is effective and enables management of patients with refractory mCRC.

Overall survival of patients with KRAS wild-type tumor treated with FOLFOX/FORFIRI±cetuximab as the first-line treatment for metastatic colorectal cancer: A meta-analysis

The addition of cetuximab to FOLFIRI or FOLFOX as the first-line treatment for metastatic colorectal cancer (mCRC) was shown to reduce the risk of disease progression and increase the chance of response in patients with KRAS wild-type disease. An updated systematic meta-analysis was undertaken to determine the efficacy of cetuximab plus FOLFIRI or FOLFOX.Major databases were searched to identify RCTs investigating wild-type KRAS mCRC after the first-line treatment, and treatment with FOLFOX/FORFIRI ± cetuximab was compared. Data on clinical efficacy and safety were pooled and compared by ORs, HRs, and 95% CIs.Five eligible trials with 1464 patients were included in the meta-analysis. Compared to FOLFOX/FORFIRI, cetuximab as the first-line therapy has improved overall survival (OS) (hazard ratio [HR] = 0.82, 95% confidence interval [CI]: 0.72-0.93, P = 0.003), progression-free survival (PFS) (HR = 0.66, 95% CI: 0.56 -0.77, P < 0.00001), and overall response rate (ORR) (odds ratio [OR] = 2.12, 95% CI: 1.70-2.65, P < 0.00001). However, Grade 3/4 AE was increased with the OR of 2.76 (95%CI: 2.01-3.78, P < 0.00001). The most common grade 3/4 toxicity in the wild-type KRAS population was neutropenia and diarrhea. For cetuximab plus FOLFIRI, there was a higher incidence of grade 3 or 4 diarrhea (OR = 1.76, 95% CI: 1.15-2.70, P = 0.01), but there was no significant difference for neutropenia (OR = 1.35, 95% CI: 1.00-1.83, P = 0.05).The addition of cetuximab in mCRC as the first-line treatment is a potential effective approach in the improved outcomes but associated with increased toxicity.

Subgroup analysis in RAISE: a randomized, double-blind phase III study of irinotecan, folinic acid, and 5-fluorouracil (FOLFIRI) plus ramucirumab or placebo in patients with metastatic colorectal carcinoma progression

BACKGROUND

The RAISE phase III clinical trial demonstrated that ramucirumab + FOLFIRI improved overall survival (OS) [hazard ratio (HR) = 0.844, P = 0.0219] and progression-free survival (PFS) (HR = 0.793, P < 0.0005) compared with placebo + FOLFIRI for second-line metastatic colorectal carcinoma (mCRC) patients previously treated with first-line bevacizumab, oxaliplatin, and a fluoropyrimidine. Since some patient or disease characteristics could be associated with differential efficacy or safety, prespecified subgroup analyses were undertaken. This report focuses on three of the most relevant ones: KRAS status (wild-type versus mutant), age (<65 versus ≥65 years), and time to progression (TTP) on first-line therapy (<6 versus ≥6 months).

PATIENTS AND METHODS

OS and PFS were evaluated by the Kaplan-Meier analysis, with HR determined by the Cox proportional hazards model. Treatment-by-subgroup interaction was tested to determine whether treatment effect was consistent between subgroup pairs.

RESULTS

Patients with both wild-type and mutant KRAS benefited from ramucirumab + FOLFIRI treatment over placebo + FOLFIRI (interaction P = 0.526); although numerically, wild-type KRAS patients benefited more (wild-type KRAS: median OS = 14.4 versus 11.9 months, HR = 0.82, P = 0.049; mutant KRAS: median OS = 12.7 versus 11.3 months, HR = 0.89, P = 0.263). Patients with both longer and shorter first-line TTP benefited from ramucirumab (interaction P = 0.9434), although TTP <6 months was associated with poorer OS (TTP ≥6 months: median OS = 14.3 versus 12.5 months, HR = 0.86, P = 0.061; TTP <6 months: median OS = 10.4 versus 8.0 months, HR = 0.86, P = 0.276). The subgroups of patients ≥65 versus <65 years also derived a similar ramucirumab survival benefit (interaction P = 0.9521) (≥65 years: median OS = 13.8 versus 11.7 months, HR = 0.85, P = 0.156; <65 years: median OS = 13.1 versus 11.9 months, HR = 0.86, P = 0.098). The safety profile of ramucirumab + FOLFIRI was similar across subgroups.

CONCLUSIONS

These analyses revealed similar efficacy and safety among patient subgroups with differing KRAS mutation status, longer or shorter first-line TTP, and age. Ramucirumab is a beneficial addition to second-line FOLFIRI treatment for a wide range of patients with mCRC.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01183780.

Evaluation of Cysteinyl Leukotriene Signaling as a Therapeutic Target for Colorectal Cancer

Colorectal cancer is the third most common cancer worldwide and is associated with significant morbidity and mortality. Current pharmacotherapy options include cytotoxic chemotherapy, anti-VEGF, and anti-EGFR targeting drugs, but these are limited by toxic side effects, limited responses and ultimately resistance. Cysteinyl leukotriene (CysLT) signaling regulates intestinal homeostasis with mounting evidence suggesting that CysLT signaling also plays a role in the pathogenesis of colorectal cancer. Therefore, CysLT signaling represents a novel target for this malignancy. This review evaluates reported links between CysLT signaling and established hallmarks of cancer in addition to its pharmacological potential as a new therapeutic target.

Clinical Implications and Future Perspectives of Circulating Tumor Cells and Biomarkers in Clinical Outcomes of Colorectal Cancer

Colorectal cancer (CRC) is a major public health problem. Early CRC detection, pretherapeutic responsiveness prediction, and postoperative micrometastasis monitoring are the hallmarks for successful CRC treatment. Here, the methodologies used for detecting circulating tumor cells (CTCs) from CRC are reviewed. In addition to the traditional CRC biomarkers, the persistent presence of posttherapeutic CTCs indicates resistance to adjuvant chemotherapy and/or radiotherapy; hence, CTCs also play a decisive role in the subsequent relapse of CRC. Moreover, the genetic and phenotypic profiling of CTCs often differs from that of the primary tumor; this difference can be used to select the most effective targeted therapy. Consequently, studying CTCs can potentially individualize treatment strategies for patients with CRC. Therefore, CTC detection and characterization may be valuable tools for refining prognosis, and CTCs can be used in a real-time tumor biopsy for designing individually tailored therapy against CRC.

Advances of Targeted Therapy in Treatment of Unresectable Metastatic Colorectal Cancer

Despite being one of the most frequently diagnosed cancers worldwide, prognosis of metastatic colorectal cancer (CRC) was poor. Development and introduction of biologic agents in treatment of patients with metastatic CRC have brought improved outcomes. Monoclonal antibodies directing epidermal growth factor receptors and vascular endothelial growth factor are main biologic agents currently used in treatment of metastatic CRC. Encouraged by results from many clinical trials demonstrating efficacy of those monoclonal antibodies, the combination therapy with those targeted agents and conventional chemotherapeutic agents has been established as the standard therapy for patients with metastatic CRC. However, emergency of resistance to those target agents has limited the efficacy of treatment, and strategies to overcome the resistance are now being investigated by newly developed biological techniques clarifying how to acquire resistance. Here, we introduce mechanisms of action of the biologic agents currently used for treatment of metastatic CRC and several landmark historical clinical studies which have changed the main stream of treatment. The mechanism of resistance to those agents, one of serious problems in treatment metastatic CRC, and ongoing clinical trials to overcome the limitations and improve treatment outcomes will also be presented in this review.

Colorectal cancer: using blood samples and tumor tissue to detect K-ras mutations

We performed a meta-analysis to assess whether blood can be substituted for tumor tissue in K-ras mutation testing. PubMed, EMBASE, MEDLINE, and BIOSIS databases were searched. Twenty-three studies including 1261 patients were included. The pooled overall sensitivity, specificity, and concordance rate were 0.69 (95% CI: 0.59-0.78), 0.96 (95% CI: 0.93-0.97), and 0.86 (95% CI: 0.82-0.89), respectively. Subgroup analysis indicated that plasma (sensitivity: 0.74; mutation rate: 0.34) exhibited superior sensitivity compared with serum (sensitivity: 0.45; mutation rate: 0.24). We conclude that blood is a suitable substitute for tumor tissue in K-ras mutation testing. K-ras mutation positivity in blood can be used to identify patients who should not receive EGFR monoclonal antibody therapy, but the absence of blood positivity does not necessarily imply negativity.

Prognostic value of KRAS mutations in colorectal cancer: A systematic review and meta-analysis

AIM: To evaluate the prognostic significance of KRAS mutations among Chinese colorectal cancer patients.

METHODS: Clinical studies on the correlation between KRAS mutations and the prognosis of colorectal cancer patients were retrieved from PubMed, Web of Science, Cochrane Library, Wan Fang database and CNKI. The latest search was done in April, 2015. Both case-control studies and cohort studies were included. Hazard ratios (HRs) were used to evaluate the outcomes. Meta-analysis was performed with Stata 12.0.

RESULTS: A total of 19 clinical studies with 2938 patients were qualified to this meta-analysis. Patients with KRAS mutations were associated with shorter overall survival (OS) (HR = 1.71, 95%CI: 1.28-2.29) and progression free survival (PFS) (HR = 2.36, 95%CI: 1.24-4.50). In addition, codons 12 and 13 mutations of KRAS were related with prognosis of colorectal cancer patients.

CONCLUSION: KRAS mutations are a possible risk factor for prognosis in patients with colorectal cancer. Patients with KRAS mutations show an increased risk of mortality and progression of disease. More clinical studies need to be performed to confirm our conclusion.

Prevalence of K-Ras mutations in hepatocellular carcinoma: A Turkish Oncology Group pilot study

Hepatocellular carcinoma (HCC) is the fifth most common male-predominant type of cancer worldwide. There is no effective treatment regimen available for advanced-stage disease and chemotherapy is generally ineffective in these patients. The number of studies on the prevalence of K-Ras mutations in HCC patients is currently limited. A total of 58 patients from 6 comprehensive cancer centers in 4 metropolitan cities of Turkey were enrolled in this study. Each center committed to enroll approximately 10 random patients whose formalin-fixed paraffin-embedded tumor tissues were available for K-Ras, exon 2 genotyping. Two methods were applied based on the availability of adequate amounts of tumor DNA. In the first method, the samples were processed using TheraScreen. The genomic DNA was further used to detect the 7 most frequent somatic mutations (35G>A; 35G>C; 35G>T; 34G>A; 34G>C; 34G>T and 38G>A) in codons 12 and 13 in exon 2 of the K-Ras oncogene by quantitative polymerase chain reaction (PCR). In the second method, the genomic DNA was amplified by PCR using primers specific for K-Ras exon 2 with the GML SeqFinder Sequencing System's KRAS kit. The identified DNA sequence alterations were confirmed by sequencing both DNA strands in two independent experiments with forward and reverse primers. A total of 40 samples had adequate tumor tissue for the mutation analysis. A total of 33 (82.5%) of the investigated samples harbored no mutations in exon 2. All the mutations were identified via a direct sequencing technique, whereas none were identified by TheraScreen. In conclusion, in our patients, HCC exhibited a remarkably low (<20%) K-Ras mutation rate. Patients harboring K-Ras wild-type tumors may be good candidates for treatment with epidermal growth factor inhibitors, such as cetuximab.

KRAS mutation testing of tumours in adults with metastatic colorectal cancer: a systematic review and cost-effectiveness analysis

BACKGROUND

Bowel cancer is the third most common cancer in the UK. Most bowel cancers are initially treated with surgery, but around 17% spread to the liver. When this happens, sometimes the liver tumour can be treated surgically, or chemotherapy may be used to shrink the tumour to make surgery possible. Kirsten rat sarcoma viral oncogene (KRAS) mutations make some tumours less responsive to treatment with biological therapies such as cetuximab. There are a variety of tests available to detect these mutations. These vary in the specific mutations that they detect, the amount of mutation they detect, the amount of tumour cells needed, the time to give a result, the error rate and cost.

OBJECTIVES

To compare the performance and cost-effectiveness of KRAS mutation tests in differentiating adults with metastatic colorectal cancer whose metastases are confined to the liver and are unresectable and who may benefit from first-line treatment with cetuximab in combination with standard chemotherapy from those who should receive standard chemotherapy alone.

DATA SOURCES

Thirteen databases, including MEDLINE and EMBASE, research registers and conference proceedings were searched to January 2013. Additional data were obtained from an online survey of laboratories participating in the UK National External Quality Assurance Scheme pilot for KRAS mutation testing.

METHODS

A systematic review of the evidence was carried out using standard methods. Randomised controlled trials were assessed for quality using the Cochrane risk of bias tool. Diagnostic accuracy studies were assessed using the QUADAS-2 tool. There were insufficient data for meta-analysis. For accuracy studies we calculated sensitivity and specificity together with 95% confidence intervals (CIs). Survival data were summarised as hazard ratios and tumour response data were summarised as relative risks, with 95% CIs. The health economic analysis considered the long-term costs and quality-adjusted life-years associated with different tests followed by treatment with standard chemotherapy or cetuximab plus standard chemotherapy. The analysis took a 'no comparator' approach, which implies that the cost-effectiveness of each strategy will be presented only compared with the next most cost-effective strategy. The de novo model consisted of a decision tree and Markov model.

RESULTS

The online survey indicated no differences between tests in batch size, turnaround time, number of failed samples or cost. The literature searches identified 7903 references, of which seven publications of five studies were included in the review. Two studies provided data on the accuracy of KRAS mutation testing for predicting response to treatment in patients treated with cetuximab plus standard chemotherapy. Four RCTs provided data on the clinical effectiveness of cetuximab plus standard chemotherapy compared with that of standard chemotherapy in patients with KRAS wild-type tumours. There were no clear differences in the treatment effects reported by different studies, regardless of which KRAS mutation test was used to select patients. In the 'linked evidence' analysis the Therascreen KRAS RGQ PCR Kit (QIAGEN) was more expensive but also more effective than pyrosequencing or direct sequencing, with an incremental cost-effectiveness ratio of £17,019 per quality-adjusted life-year gained. In the 'assumption of equal prognostic value' analysis the total costs associated with the various testing strategies were similar.

LIMITATIONS

The results assume that the differences in outcomes between the trials were solely the result of the different mutation tests used to distinguish between patients; this assumption ignores other factors that might explain this variation.

CONCLUSIONS

There was no strong evidence that any one KRAS mutation test was more effective or cost-effective than any other test.

STUDY REGISTRATION

PROSPERO CRD42013003663.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Activation of KRAS promotes the mesenchymal features of basal-type breast cancer

Basal-type breast cancers are among the most aggressive and deadly breast cancer subtypes, displaying a high metastatic ability associated with mesenchymal features. However, the molecular mechanisms underlying the maintenance of mesenchymal phenotypes of basal-type breast cancer cells remain obscure. Here, we report that KRAS is a critical regulator for the maintenance of mesenchymal features in basal-type breast cancer cells. KRAS is preferentially activated in basal-type breast cancer cells as compared with luminal type. By loss and gain of KRAS, we found that KRAS is necessary and sufficient for the maintenance of mesenchymal phenotypes and metastatic ability through SLUG expression. Taken together, this study demonstrates that KRAS is a critical regulator for the metastatic behavior associated with mesenchymal features of breast cancer cells, implicating a novel therapeutic target for basal-type breast cancer.

Colorectal cancer in Chinese patients: current and emerging treatment options

Colorectal cancer is the second most common cancer in Hong Kong and its incidence is rising in economically developed Chinese cities, including Hong Kong and Shanghai. Several studies conducted in the People's Republic of China have characterized the unique molecular epidemiology of familial colorectal cancer syndromes and molecular biomarkers such as microsatellite instability and genetic mutations (eg, KRAS, NRAS, BRAF, PIK3CA, ERCC1) in Chinese populations. Interethnic differences in anticancer drug response and toxicity have been well described in many cancers, and this review examined the literature with regard to the tolerance of Chinese patients to commonly used chemotherapeutic regimens and targeted therapies for metastatic colorectal cancer. Studies on the pharmacogenomic differences in drug metabolizing and DNA repair enzymes between Chinese, North Asians, and Caucasian patients were also reviewed.

Colorectal cancer in Chinese patients: current and emerging treatment options

Colorectal cancer is the second most common cancer in Hong Kong and its incidence is rising in economically developed Chinese cities, including Hong Kong and Shanghai. Several studies conducted in the People's Republic of China have characterized the unique molecular epidemiology of familial colorectal cancer syndromes and molecular biomarkers such as microsatellite instability and genetic mutations (eg, KRAS, NRAS, BRAF, PIK3CA, ERCC1) in Chinese populations. Interethnic differences in anticancer drug response and toxicity have been well described in many cancers, and this review examined the literature with regard to the tolerance of Chinese patients to commonly used chemotherapeutic regimens and targeted therapies for metastatic colorectal cancer. Studies on the pharmacogenomic differences in drug metabolizing and DNA repair enzymes between Chinese, North Asians, and Caucasian patients were also reviewed.

Decreasing relapse in colorectal cancer patients treated with cetuximab by using the activating KRAS detection chip

The KRAS oncogene was among the first genetic alterations in colorectal cancer (CRC) to be discovered. Moreover, KRAS somatic mutations might be used for predicting the efficiency of anti-epidermal growth factor receptor therapeutic drugs. Because the KRAS mutations are similar in the primary CRC and/or the CRC metastasis, KRAS mutation testing can be performed on both specimen types. The purpose of this study was to investigate the clinical advantage of using a KRAS pathway-associated molecule analysis chip to analyze CRC patients treated with cetuximab. Our laboratory developed a KRAS pathway-associated molecule analysis chip and a weighted enzymatic chip array (WEnCA) technique, activating KRAS detection chip, which can detect KRAS mutation status by screening circulating cancer cells in the bloodstream. We prospectively enrolled 210 stage II-III CRC patients who received adjuvant oxaliplatin plus infusional 5-fluorouracil/leucovorin (FOLFOX)-4 chemotherapy with or without cetuximab. We compared the chip results of preoperative blood specimens with disease control status in these patients. Among the 168 CRC patients with negative chip results, 119 were treated with FOLFOX-4 plus cetuximab chemotherapy, and their relapse rate was 35.3 % (42/119). In contrast, the relapse rate was 71.4 % among the patients with negative chip results who received FOLFOX-4 treatment alone (35/49). Negative chip results were significantly correlated with better treatment outcomes in the FOLFOX-4 plus cetuximab group (P < 0.001). We suggest that the activating KRAS detection chip is a potential tool for predicting clinical outcomes in CRC patients following FOLFOX-4 treatment with or without cetuximab therapy.

A method for the second-site screening of K-Ras in the presence of a covalently attached first-site ligand

K-Ras is a well-validated cancer target but is considered to be "undruggable" due to the lack of suitable binding pockets. We previously discovered small molecules that bind weakly to K-Ras but wanted to improve their binding affinities by identifying ligands that bind near our initial hits that we could link together. Here we describe an approach for identifying second site ligands that uses a cysteine residue to covalently attach a compound for tight binding to the first site pocket followed by a fragment screen for binding to a second site. This approach could be very useful for targeting Ras and other challenging drug targets.

The prognostic values of EGFR expression and KRAS mutation in patients with synchronous or metachronous metastatic colorectal cancer

BACKGROUND

The epidermal growth factor receptor (EGFR)/RAS/RAF/MEK/MAPK pathway is an important pathway in the carcinogenesis, invasion and metastasis of colorectal cancers (CRCs). We conducted a retrospective study to determine the prognostic values of EGFR expression and KRAS mutation in patients with metastatic CRC (mCRC) based on synchronous or metachronous status.

METHODS

From October 2002 to March 2012, 205 patients with mCRC were retrospectively analyzed; 98 were found to have metachronous mCRC while 107 were found to have synchronous mCRC. The EGFR expressions were determinate by IHC (immunohistochemistry) analysis and categorized 1+ (weak intensity), 2+ (moderate intensity), and 3+ (strong intensity). Genomic DNA was isolated from frozen primary CRC tissues and direct sequencing of KRAS was performed. The clinicopathological features of these mCRC patients were retrospectively investigated according to EGFR expression and KRAS mutation status. Moreover, we analyzed the prognostic values of EGFR expression and KRAS mutation among these patients.

RESULTS

Of the 205 patients with mCRC, EGFR expression was analyzed in 167 patients, and positive EGFR expression was noted in 140 of those patients (83.8%). KRAS mutation was investigated in 205 patients and mutations were noted in 88 of those patients (42.9%). In patients with metachronous mCRC, positive EGFR expression was significantly correlated with well-and moderately-differentiated tumors (P=0.028), poorer disease-free survival (DFS) (P<0.001), and overall survival (OS) (P<0.001). Furthermore, positive EGFR expression was a significant independent prognostic factor of DFS (P=0.006, HR: 4.012, 95% CI: 1.130-8.445) and OS (P=0.028, HR: 3.090, 95% CI: 1.477-10.900) in metachronous mCRC patients. KRAS mutation status was not significantly related to DFS and OS of patients with metachronous mCRC; likewise, KRAS mutation status was not significantly different in the progression-free survival (PFS) and OS of patients with synchronous mCRC (all P>0.05).

CONCLUSIONS

The present study demonstrated that EGFR expression has prognostic value only for patients with metachronous mCRC. However, KRAS mutation did not have prognostic value in patients with metachronous or synchronous mCRC.

Mutations in specific codons of the KRAS oncogene are associated with variable resistance to neoadjuvant chemoradiation therapy in patients with rectal adenocarcinoma

BACKGROUND

Mutations in KRAS and TP53 are common in colorectal carcinogenesis and are associated with resistance to therapy. Rectal cancers carrying both mutations are less likely to respond to neoadjuvant chemoradiation therapy (CRT) compared with wild-type tumors. Codon-specific KRAS mutations are associated with variable resistance to targeted therapies, but their association with rectal cancer response to CRT remains unclear. Our objective was to establish a correlation between specific KRAS mutations and rectal cancer response to CRT and to investigate if the correlation was related to a different association between KRAS and TP53 mutations.

METHODS

A total of 148 stage II-III rectal cancer patients underwent preoperative CRT followed by surgery. DNA was extracted from pretreatment tumor biopsies and paired normal surgical tissues and KRAS and TP53 genotyping was performed. Specific KRAS mutations were then correlated with tumor response and with concurrent TP53 mutation.

RESULTS

A total of 60 patients had KRAS mutation, 12 in codon 13 and 48 in other locations. Also, 80 patients had TP53 mutation; 27 had concurrent KRAS/TP53 mutations. Tumors with any KRAS mutation were less likely to have a pCR compared with wild-type KRAS (p = 0.006). Specifically, no tumors with KRAS codon 13 mutations had a pCR (p = 0.03). Tumors with KRAS codon 13 mutations also had a higher incidence of concurrent TP53 mutation compared with tumors with other KRAS mutations (p = 0.02).

CONCLUSIONS

Mutations in different KRAS codons may have different effects on rectal cancer resistance to CRT. This variable resistance may be related to a different frequency of TP53 mutations in KRAS mutant tumors.

Molecular biomarkers of resistance to anti-EGFR treatment in metastatic colorectal cancer, from classical to innovation

BACKGROUND

Systematic dissection of the EGFR pathway was considered as the best way to identify putative markers of resistance to anti-EGFR therapies. This kind of approach leaves other, less known but by no means less important, putative mechanisms of resistance. We tried to shed some light on these mechanisms of resistance.

MATERIALS AND METHODS

We performed a research through Pubmed database of all published articles highlighting mechanisms of resistance to Cetuximab and Panitumumab based therapies, published in 2000-2012 period.

CONCLUSIONS

We reviewed the "classical" molecular factors, extensively analyzed as predictive factors for efficacy to anti-EGFR therapy, such as K-ras, B-raf, and PI3K-mTOR-Akt, focusing on their predictive or prognostic value and on the controversial aspects of the biomarker analysis for clinical practice. On the second part we will then move on to other less known molecular markers, for the future understanding of biological mechanisms underlying anti-EGFR therapy resistance, such as non-canonical heterodimer candidates, microRNA, IGF1-IGF1R, HGF-cMET and secondary mutations of EGFR.

Epidermal growth factor receptor expression and KRAS and BRAF mutations: study of 39 sinonasal intestinal-type adenocarcinomas

Sinonasal intestinal-type adenocarcinomas (ITACs) are uncommon tumors of poor prognosis defined by their similarities to colorectal adenocarcinomas. The involvement of the epidermal growth factor receptor (EGFR) pathway in colorectal adenocarcinoma oncogenesis is well established, and the same is expected to apply to ITACs. In a series of 39 ITACs, we investigated EGFR amplification and chromosome 7 polysomy by fluorescence in situ hybridization; EGFR, KRAS, and BRAF mutational status by polymerase chain reaction sequencing; EGFR variant messenger RNA expression by quantitative reverse transcriptase polymerase chain reaction; and EGFR protein expression by immunohistochemistry with antibodies targeting the extracellular domain, the intracellular domain, and the phosphorylated isoform. The findings were analyzed with respect to clinical data, histologic typing, and patient outcome. EGFR amplification was observed in 3 cases with a focal distribution. EGFR proteins were overexpressed in all these foci with both extracellular domain and intracellular domain antibodies, suggesting involvement of the whole receptor. Chromosome 7 polysomy was observed in 15 cases and was not associated with EGFR protein expression. EGFR, KRAS, or BRAF mutations were observed in 5 different cases. The EGFRvIII mutant was not detected. In all cases, EGFR variants were expressed. There was no association between these molecular features and patient survival. In conclusion, (1) our study revealed various EGFR expression patterns in ITACs, indicating tumor heterogeneity; (2) EGFR amplification should be distinguished from chromosome 7 polysomy; (3) fluorescence in situ hybridization analysis could be guided by immunohistochemistry; and (4) ITACs share common alterations of the EGFR pathway with colorectal adenocarcinomas, except for a lower frequency of KRAS and BRAF mutations.

Effect of low-frequency KRAS mutations on the response to anti-EGFR therapy in metastatic colorectal cancer

BACKGROUND

Only patients with wild-type (WT) KRAS tumors benefit from anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (Mabs) in metastatic colorectal cancer (mCRC). Pyrosequencing is now widely used for the determination of KRAS mutation burden and a conservative cut-off point of 10% has been defined. Up until now, the impact of low-frequency KRAS mutations (<10%) on the response to anti-EGFR Mabs has yet to be evaluated.

PATIENTS AND METHODS

Tumors from patients receiving anti-EGFR Mabs based on a WT genotype for KRAS, as determined using direct sequencing, have been retrospectively analyzed by pyrosequencing. Patients were categorized as WT (no KRAS mutation) or low-frequency mutation when KRAS mutation was <10% (KRAS low MT).

RESULTS

A total of 168 patients treated by anti-EGFR Mabs for mCRC were analyzed. According to pyrosequencing, 138 tumors remained KRAS WT, while 30 tumors were KRAS low MT. In the KRAS low MT and KRAS WT groups, the response rates were 6.7% and 37.0%, respectively, while stabilization amounted to 23.3% versus 32.6% and progression to 70% versus 29% (P < 0.01). Progression-free survival (PFS) was 2.7 ± 0.5 months for KRAS low MT and was 6.0 ± 0.3 months for KRAS WT (P < 0.01).

CONCLUSIONS

These results appear to validate consideration of low-frequency KRAS mutation tumors as positive, and justify a large-scale prospective study.

Oncogenic mutations and microsatellite instability phenotype predict specific anatomical subsite in colorectal cancer patients

In colorectal cancer (CRC) oncogenic mutations such as KRAS alterations, are considered standard molecular biomarkers that predict the clinical benefit for targeted intervention with epidermal growth factor receptor (EGFR) inhibitors. In addition, these mutations are associated with specific anatomical area in colon tumor development, as BRAF mutations with the microsatellite instability (MSI). In this translational study, we aimed to assess the mutation frequencies of the EGFR (hotspot area and polyadenine deletions A13_del), KRAS, BRAF(V600E), and PIK3CA oncogenes in a series of 280 CRC patients. MSI phenotypes are also considered in this series. All patients' clinicopathological data were assessed for statistical analysis and its associations were validated. We verified multiple associations between oncogenic mutations and determined clinicopathological tumor features (1) EGFR A13_deletions are associated with right colon carcinoma (P<0.005), mucinous histotype (P=0.042), G3 grading (P=0.024), and MSI status (P<0.005); (2) PIK3CA mutations are related mucinous histotype (P=0.021); (3) KRAS(G12) and KRAS(G13) mutations are correlated, respectively, with the left and right colon cancer development (P<0.005), and finally (4) MSI is associated with right colon tumors (P<0.005). Mostly, we verified a higher frequency rate of the KRAS(G13) and EGFR A13_del oncogene mutations in right colon cancer; whereas KRAS(G12) codon mutation occurs more frequently in left colon cancers. In particular, we assessed that right vs left colon cancer are associated with specific molecular characteristics. These evidences, in association with clinicopathological data, can delineate novel approaches for the CRC classification and targeted intervention.

Expression of EGFR, HER2, phosphorylated ERK and phosphorylated MEK in colonic neoplasms of familial adenomatous polyposis patients

PURPOSE

The expression of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) is associated with poor prognosis in sporadic colorectal carcinoma (CRC). EGFR inhibitors are approved for the treatment of refractory CRC. The aim of this study was to investigate the expression of EGFR and HER2 and downstream extracellular signal regulated kinase (ERK) and mitogen activated protein kinase (MAPK) in non-neoplastic colonic mucosa, adenomas and carcinomas from familial adenomatous polyposis coli (FAP) patients, exploring the expression along the adenoma-carcinoma sequence.

METHODS

The expression of EGFR, HER2, phosphorylated MAPK/ERK kinase (pMEK) and phosphorylated ERK (pERK) proteins was studied by immunohistochemistry in samples of colonic non-neoplastic mucosa (n = 65), adenomas (n = 149) and adenocarcinomas (n = 16) from each of the 16 FAP patients.

RESULTS

For HER2, only weak cytoplasmic expression was seen in 8% of adenomas, 6% of carcinomas and 3% of the non-neoplastic mucosa. EGFR was expressed in non-neoplastic mucosa, adenomas and carcinomas with a statistically significant increase in expression in adenomas compared with non-neoplastic mucosa (p < 0.001). There was also a statistically significant increase in nuclear staining intensity for pERK (p < 0.001) and pMEK (p < 0.001) in adenomas compared to non-neoplastic mucosa.

CONCLUSIONS

This is the first study investigating the expression of these receptors in non-neoplastic mucosa, adenomas and carcinomas from FAP patients. HER2 is not upregulated in the tumours of FAP patients, while EGFR appears to be upregulated in most adenomas and carcinomas, with associated upregulation of pERK and pMEK. We conclude that EGFR and downstream members of its signalling pathway, but not HER2, may be potential therapeutic targets in FAP patients.

Novel antineoplastics targeting genetic changes in colorectal cancer

Cytotoxic chemotherapy remains the mainstay of the medical -management of colorectal cancer (CRC). Research over the last two decades has led to a molecular understanding of the oncogenic mechanisms involved in CRC and has contributed to the rational development of antineoplastics that target these mechanisms. During carcinogenesis, genetic changes often occur in molecules that play key functional roles in cancer such as cell proliferation, angiogenesis, apoptosis, cell death and immune-mediated destruction of cancer cells. Here, we review novel antineoplastics that are approved or in development for CRC that target molecules associated with genetic aberrations in CRC. Some of these targeted antineoplastics have proven effective against other solid tumors and hold promise in treating CRC whereas others are now routinely used in combination with cytotoxic agents. This article reviews antineoplastics that target genetic changes in CRC, their antitumor mechanisms, and their stage of development.

Recent advances in detection of potential prognostic markers in colorectal cancer

Colorectal cancer (CRC) is one of the most common malignant tumors. Recent development in molecular biology techniques, gene sequencing and molecular diagnostics has led to the discovery of some new prognostic markers in colorectal cancer. So far, K-ras is a valid prognostic marker that can be used in clinical practice. However, many markers investigated suffer from technical shortcomings, which result mainly from lack of quantitative techniques to capture the impact of molecular alterations. This paper gives an overview of recent advances in research of promising biological prognostic markers in CRC, including RHAMM, FOXP3⁺ Treg, HSP27, PIK3CA, and PTEN.

Expression of Abelson interactor 1 (Abi1) correlates with inflammation, KRAS mutation and adenomatous change during colonic carcinogenesis

Background

Abelson interactor 1 (Abi1) is an important regulator of actin dynamics during cytoskeletal reorganization. In this study, our aim was to investigate the expression of Abi1 in colonic mucosa with and without inflammation, colonic polyps, colorectal carcinomas (CRC) and metastases as well as in CRC cell lines with respect to BRAF/KRAS mutation status and to find out whether introduction of KRAS mutation or stimulation with TNFalpha enhances Abi1 protein expression in CRC cells.

Methodology/Principal Findings

We immunohistochemically analyzed Abi1 protein expression in 126 tissue specimens from 95 patients and in 5 colorectal carcinoma cell lines with different mutation status by western immunoblotting. We found that Abi1 expression correlated positively with KRAS, but not BRAF mutation status in the examined tissue samples. Furthermore, Abi1 is overexpressed in inflammatory mucosa, sessile serrated polyps and adenomas, tubular adenomas, invasive CRC and CRC metastasis when compared to healthy mucosa and BRAF-mutated as well as KRAS wild-type hyperplastic polyps. Abi1 expression in carcinoma was independent of microsatellite stability of the tumor. Abi1 protein expression correlated with KRAS mutation in the analyzed CRC cell lines, and upregulation of Abi1 could be induced by TNFalpha treatment as well as transfection of wild-type CRC cells with mutant KRAS. The overexpression of Abi1 could be abolished by treatment with the PI3K-inhibitor Wortmannin after KRAS transfection.

Conclusions/Significance

Our results support a role for Abi1 as a downstream target of inflammatory response and adenomatous change as well as oncogenic KRAS mutation via PI3K, but not BRAF activation. Furthermore, they highlight a possible role for Abi1 as a marker for early KRAS mutation in hyperplastic polyps. Since the protein is a key player in actin dynamics, our data encourages further studies concerning the exact role of Abi1 in actin reorganization upon enhanced KRAS/PI3K signalling during colonic tumorigenesis.