KRAS mutation testing in metastatic colorectal cancer

KRAS mutations in colorectal cancer: impacts on tumor microenvironment and therapeutic implications

INTRODUCTION

Despite decreasing trends in incidence, colorectal cancer (CRC) is still a major contributor to malignancy-related morbidities and mortalities. Groundbreaking advances in immunotherapies and targeted therapies benefit a subset of CRC patients, with sub-optimal outcomes. Hence, there is an unmet need to design and manufacture novel therapies, especially for advanced/metastatic disease. KRAS, the most highly mutated proto-oncogene across human malignancies, particularly in pancreatic adenocarcinoma, non-small cell lung cancer, and CRC, is an on-off switch and governs several fundamental cell signaling cascades. KRAS mutations not only propel the progression and metastasis of CRC but also critically modulate responses to targeted therapies.

AREAS COVERED

We discuss the impacts of KRAS mutations on the CRC's tumor microenvironment and describe novel strategies for targeting KRAS and its associated signaling cascades and mechanisms of drug resistance.

EXPERT OPINION

Drug development against KRAS mutations has been challenging, mainly due to structural properties (offering no appropriate binding site for small molecules), critical functions of the wild-type KRAS in non-cancerous cells, and the complex network of its downstream effector pathways (allowing malignant cells to develop resistance). Pre-clinical and early clinical data offer promises for combining KRAS inhibitors with immunotherapies and targeted therapies.

Comprehensive identification of a migrasomes-associated long non-coding RNA signature to predict the prognosis and treatment options in colon adenocarcinoma

BACKGROUND

Migrasomes, recently discovered cellular substructures, may play a crucial role in cancer progression, treatment response, and prognosis. However, the prognostic value of migrasome-associated long non-coding RNAs (lncRNAs) in colon adenocarcinoma (COAD) remains unexplored.

METHODS

RNA-seq data from 459 COAD patients, including clinical characteristics and outcome information, were obtained from The Cancer Genome Atlas. A risk model was constructed through co-expression analysis of migrasome genes and lncRNAs, followed by Cox regression and least absolute shrinkage and selection operator analysis to identify prognostic lncRNAs. Functional enrichment analyses were performed to elucidate underlying biological mechanisms. Immune landscape characterization utilized ESTIMATE, CIBERSORT, Tumor Immune Estimation Resource (TIME), and single-sample Gene Set Enrichment Analysis (ssGSEA). Drug sensitivity analysis was conducted for select therapeutic agents.

RESULTS

Nine prognostic lncRNAs (AC010463.3, AL590483.4, AP005264.1, ZEB1-AS1, AC104088.1, PRKAR1B-AS2, AC009315.1, SUCLG2-AS1, and AC006111.2) were identified and incorporated into a risk model. Low-risk patients demonstrated significantly improved survival outcomes. The model exhibited independent prognostic capability, with AUCs of 0.783, 0.749, and 0.713 for one-, three-, and five-year survival, respectively, in the training cohort. High-risk patients displayed reduced overall survival and elevated tumor mutation burden. Additionally, these patients showed decreased sensitivity to therapeutic agents, including Oxaliplatin, Irinotecan, and 5-Fluorouracil.

CONCLUSION

Our novel migrasome-associated lncRNA signature demonstrates robust predictive capacity for both prognosis and chemotherapeutic sensitivity in COAD, potentially facilitating personalized treatment strategies and improved patient management.

Prediction of Kirsten rat sarcoma (KRAS) mutation in rectal cancer with amide proton transfer-weighted magnetic resonance imaging

Background

Kirsten rat sarcoma (KRAS) mutation drives resistance to anti-epidermal growth factor receptor (anti-EGFR)-targeted therapies in rectal cancer. Amide proton transfer-weighted magnetic resonance imaging (APTw MRI) might be a supplement to the evaluation of KRAS mutation because the APTw value can reflect mobile cellular protein content in vivo. This study aimed to determine whether APTw MRI could predict KRAS mutation in rectal cancer and compare this technique with diffusion-weighted imaging (DWI).

Methods

This retrospective study reviewed 153 consecutive patients with rectal cancer from April 2019 to June 2021 in our hospital. Among them, a total of 55 patients who did not undergo neoadjuvant chemoradiotherapy and underwent preoperative APTw MRI, DWI, and postoperative KRAS tests were included in this study. In two-dimensional APTw images, two radiologists manually delineated three regions of interest (ROIs) along tumor contour in the largest slice and the adjacent two slices of tumor respectively. The mean APTw value within a ROI was calculated, and the values of three ROIs were averaged for each patient. In consecutive DWI images, two radiologists depicted the ROIs of the whole lesion, and the mean apparent diffusion coefficient (ADC) was generated. The intraclass correlation coefficient (ICC), Shapiro-Wilk test and Student's t-test were used for statistical analyses. Receiver operating characteristic (ROC) curves were constructed for APTw and ADC values respectively, and the area under the curve (AUC) was used to evaluate the diagnostic performance for the prediction of KRAS mutation.

Results

Among these 55 patients, KRAS mutation occurred in 21 patients. The ICCs of two independent raters for APTw and ADC values were 0.937 [95% confidence interval (CI), 0.914-0.953] and 0.976 (95% CI, 0.959-0.986), respectively. ADC values did not show a statistically significant difference between the KRAS-mutant group and the wild type (WT) group (P=0.733). KRAS-mutant tumors exhibited a higher APTw value than WT tumors in patients with rectal non-mucinous adenocarcinoma (3.324%±0.685% vs. 2.230%±0.833%, P<0.001). The AUC of the APTw value was 0.827 (95% CI, 0.701-0.916), with a cutoff value of 2.4% (sensitivity, 95.2%; specificity, 55.9%).

Conclusions

DWI cannot differentiate mutant KRAS genes from WT genes in patients with rectal cancer, but APTw MRI has potential for evaluating KRAS mutation in rectal cancer. The APTw value had moderate diagnostic performance in the prediction of KRAS mutation with a high sensitivity but a low specificity. APTw MRI might be a promising supplement to KRAS genomic analysis in rectal cancer patients.

A multicenter study: predicting KRAS mutation and prognosis in colorectal cancer through a CT-based radiomics nomogram

PURPOSE

To establish a CT-based radiomics nomogram for preoperative prediction of KRAS mutation and prognostic stratification in colorectal cancer (CRC) patients.

METHODS

In a retrospective analysis, 408 patients with confirmed CRC were included, comprising 168 cases in the training set, 111 cases in the internal validation set, and 129 cases in the external validation set. Radiomics features extracted from the primary tumors were meticulously screened to identify those closely associated with KRAS mutation. Subsequently, a radiomics nomogram was constructed by integrating these radiomics features with clinically significant parameters. The diagnostic performance was assessed through the area under the receiver operating characteristic curve (AUC). Lastly, the prognostic significance of the nomogram was explored, and Kaplan-Meier analysis was employed to depict survival curves for the high-risk and low-risk groups.

RESULTS

A radiomics model was constructed using 19 radiomics features significantly associated with KRAS mutation. Furthermore, a nomogram was developed by integrating these radiomics features with two clinically significant parameters (age, tumor location). The nomogram achieved AUCs of 0.834, 0.813, and 0.811 in the training set, internal validation set, and external validation set, respectively. Additionally, the nomogram effectively stratified patients into high-risk (KRAS mutation) and low-risk (KRAS wild-type) groups, demonstrating a significant difference in overall survival (P < 0.001). Patients categorized in the high-risk group exhibited inferior overall survival in contrast to those classified in the low-risk group.

CONCLUSIONS

The CT-based radiomics nomogram demonstrates the capability to effectively predict KRAS mutation in CRC patients and stratify their prognosis preoperatively.

Detecting colorectal cancer using genetic and epigenetic biomarkers: screening and diagnosis

Colorectal cancer (CRC) is one of the most frequent types of cancer, with high incidence rates and mortality globally. The extended timeframe for developing CRC allows for the potential screening and early identification of the disease. Furthermore, studies have shown that survival rates for patients with cancer are increased when diagnoses are made at earlier stages. Recent research suggests that the development of CRC, including its precancerous lesion, is influenced not only by genetic factors but also by epigenetic variables. Studies suggest epigenetics plays a significant role in cancer development, particularly CRC. While this approach is still in its early stages and faces challenges due to the variability of CRC, it shows promise as a potential method for understanding and addressing the disease. This review examined the current evidence supporting genetic and epigenetic biomarkers for screening and diagnosis. In addition, we also discussed the feasibility of translating these methodologies into clinical settings. Several markers show promising potential, including the methylation of vimentin (VIM), syndecan-2 (SDC2), and septin 9 (SEPT9). However, their application as screening and diagnostic tools, particularly for early-stage CRC, has not been fully optimized, and their effectiveness needs validation in large, multi-center patient populations. Extensive trials and further investigation are required to translate genetic and epigenetic biomarkers into practical clinical use. biomarkers, diagnostic biomarkers.

Does RAS Status Increase the Prevalence of Positive Resection Margin in Colorectal Liver Metastasis? A Systematic Review and Meta-Analysis

BACKGROUND

Colorectal liver metastasis has a high incidence, and RAS oncogene mutation status carries significant prognostic information. We aimed to assess whether RAS-mutated patients present more or less frequently with positive margins in their hepatic metastasectomy.

METHODS

We performed a systematic review and meta-analysis of studies from PubMed, Embase, and Lilacs databases. We analyzed liver metastatic colorectal cancer studies, which included information on RAS status and had surgical margin analysis of the liver metastasis. Odds ratios were computed using a random-effect model due to anticipated heterogeneity. We further performed a subanalysis limited to studies that included only patients with KRAS instead of all-RAS mutations.

RESULTS

From the 2,705 studies screened, 19 articles were included in the meta-analysis. There were 7,391 patients. The prevalence of positive resection margin was not significantly different between patients carrier vs non-carrier for the all-RAS mutations (OR .99; 95% CI 0.83-1.18; P = .87), and for only KRAS mutation (OR .93; 95% CI 0.73-1.19; P = .57).

CONCLUSIONS

Despite the strong correlation between colorectal liver metastasis prognosis and RAS mutation status, our meta-analysis's results suggest no correlation between the RAS status and the prevalence of positive resection margins. The findings contribute to a better understanding of the RAS mutation's role in the surgical resections of colorectal liver metastasis.

Targeting KRASG12V mutations with HLA class II-restricted TCR for the immunotherapy in solid tumors

KRAS mutation is a significant driving factor of tumor, and KRAS^G12V mutation has the highest incidence in solid tumors such as pancreatic cancer and colorectal cancer. Thus, KRAS^G12V neoantigen-specific TCR-engineered T cells could be a promising cancer treatment approach for pancreatic cancer. Previous studies had reported that KRAS^G12V-reactive TCRs originated from patients' TILs could recognized KRAS^G12V neoantigen presented by specific HLA subtypes and remove tumor persistently in vitro and in vivo. However, TCR drugs are different from antibody drugs in that they are HLA-restricted. The different ethnic distribution of HLA greatly limits the applicability of TCR drugs in Chinese population. In this study, we have identified a KRAS^G12V-specific TCR which recognized classII MHC from a colorectal cancer patient. Interestingly, we observed that KRAS^G12V-specific TCR-engineered CD4⁺ T cells, not CD8⁺ T cells, demonstrated significant efficacy in vitro and in xenograft mouse model, exhibiting stable expression and targeting specificity of TCR when co-cultured with APCs presenting KRAS^G12V peptides. TCR-engineered CD4⁺ T cells were co-cultured with APCs loaded with neoantigen, and then HLA subtypes were identified by the secretion of IFN-γ. Collectively, our data suggest that TCR-engineered CD4⁺ T cells can be used to target KRAS^G12V mutation presented by HLA-DPB1*03:01 and DPB1*14:01, which provide a high population coverage and are more suitable for the clinical transformation for Chinese, and mediate tumor killing effect like CD8⁺ T cells. This TCR hold promise for precision therapy in immunotherapy of solid tumors as an attractive candidate.

Molecular methods for colorectal cancer screening: Progress with next-generation sequencing evolution

Currently, colorectal cancer (CRC) represents the third most common malignancy and the second most deadly cancer worldwide, with a higher incidence in developed countries. Like other solid tumors, CRC is a heterogeneous genomic disease in which various alterations, such as point mutations, genomic rearrangements, gene fusions or chromosomal copy number alterations, can contribute to the disease development. However, because of its orderly natural history, easily accessible onset location and high lifetime incidence, CRC is ideally suited for preventive intervention, but the many screening efforts of the last decades have been compromised by performance limitations and low penetrance of the standard screening tools. The advent of next-generation sequencing (NGS) has both facilitated the identification of previously unrecognized CRC features such as its relationship with gut microbial pathogens and revolutionized the speed and throughput of cataloguing CRC-related genomic alterations. Hence, in this review, we summarized the several diagnostic tools used for CRC screening in the past and the present, focusing on recent NGS approaches and their revolutionary role in the identification of novel genomic CRC characteristics, the advancement of understanding the CRC carcinogenesis and the screening of clinically actionable targets for personalized medicine.

Systemic treatment for metastatic colorectal cancer

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

Systemic treatment for metastatic colorectal cancer

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

Medicinal chemistry perspective of pyrido[2,3-d]pyrimidines as anticancer agents

Cancer is a major cause of deaths across the globe due to chemoresistance and lack of selective chemotherapy. Pyrido[2,3-d]pyrimidine is an emerging scaffold in medicinal chemistry having a broad spectrum of activities, including antitumor, antibacterial, CNS depressive, anticonvulsant, and antipyretic activities. In this study, we have covered different cancer targets, including tyrosine kinase, extracellular regulated protein kinases - ABL kinase, phosphatidylinositol-3 kinase, mammalian target of rapamycin, p38 mitogen-activated protein kinases, BCR-ABL, dihydrofolate reductase, cyclin-dependent kinase, phosphodiesterase, KRAS and fibroblast growth factor receptors, their signaling pathways, mechanism of action and structure-activity relationship of pyrido[2,3-d]pyrimidine derivatives as inhibitors of the above-mentioned targets. This review will represent the complete medicinal and pharmacological profile of pyrido[2,3-d]pyrimidines as anticancer agents, and will help scientists to design new selective, effective and safe anticancer agents.

Identification of BIK as an unfavorable prognostic marker and novel therapeutic target in microsatellite stable colorectal cancer harboring KRAS mutations

KRAS mutations lead to persistent activation of multiple downstream effectors that drive the cancer phenotype. Approximately 30%-50% of colorectal cancer (CRC) patients harbor KRAS mutations, which confer more aggressive tumor biology and shorter overall survival (OS), especially in microsatellite stable (MSS) metastatic CRC. Given that KRAS mutant protein has been proven difficult to target directly, identifying genes that function closely with KRAS and targeting these genes seems to be a promising therapeutic strategy for KRAS-mutated MSS CRC. Here, KRAS function-sensitive genes were identified by assessing the correlation between gene dependency scores from CRISPR knockout screens and KRAS mRNA expression in KRAS-mutated MSS CRC cell lines in the Cancer Cell Line Encyclopedia (CCLE) database. If the correlation coefficient was ≥ 0.6, the gene was considered a KRAS function-sensitive gene. Then KRAS function-sensitive genes related to prognosis were screened out in The Cancer Genome Atlas (TCGA) cohort, and the prognostic value was validated in the Gene Expression Omnibus (GEO) cohort. Single-sample gene set enrichment analysis (ssGSEA) was performed to investigate the potential mechanisms. PockDrug-Server was used to predict the druggability of candidate genes. The results showed that in 20 KRAS-mutated MSS CRC cell lines, 13 genes were identified as KRAS function-sensitive genes. Of these 13 genes, only BIK expression was significantly associated with progression-free survival (PFS) and OS, and the BIK-high patients had significantly poorer PFS (HR=3.18, P=0.020) and OS (HR=4.74, P=0.030) than the BIK-low patients. Multivariate Cox regression analysis revealed high BIK expression as an independent predictor for poorer prognosis in KRAS-mutated MSS CRC. The prognostic value of BIK was also successfully validated in a GEO cohort. The results of ssGSEA showed that the BIK-high group was more prone to strong metastasis activity than the BIK-low group. Pocket druggability prediction analysis presented that BIK had three druggable pockets, and their druggability scores were above 0.8. These findings suggested that BIK is a promising prognostic marker and therapeutic target in KRAS-mutated MSS CRC.

Development of a Nanostructured Electrochemical Genosensor for the Detection of the K-ras Gene

In the scientific literature, it has been documented that electrochemical genosensors are novel analytical tools with proven clinical diagnostic potential for the identification of carcinogenic processes due to genetic and epigenetic alterations, as well as infectious diseases due to viruses or bacteria. In the present work, we describe the construction of an electrochemical genosensor for the identification of the k12p.1 mutation; it was based on use of Screen-Printed Gold Electrode (SPGE), Cyclic Voltammetry (CV), and Atomic Force Microscopy (AFM), for the monitoring the electron transfer trough the functionalized nanostructured surface and corresponding morphological changes. The sensitivity of the genosensor showed a linear response for the identification of the k12p.1 mutation of the K-ras gene in the concentration range of 10 fM to 1 μM with a detection limit of 7.96 fM in the presence of doxorubicin (Dox) as DNA intercalating agent and indicator of the hybridization reaction. Thus, the electrochemical genosensor developed could be useful for the identification of diseases related with the K-ras oncogene.

A Review of the Nucleic Acid-Based Lateral Flow Assay for Detection of Breast Cancer from Circulating Biomarkers at a Point-of-Care in Low Income Countries

The current levels of breast cancer in African women have contributed to the high mortality rates among them. In South Africa, the incidence of breast cancer is also on the rise due to changes in behavioural and biological risk factors. Such low survival rates can be attributed to the late diagnosis of the disease due to a lack of access and the high costs of the current diagnostic tools. Breast cancer is asymptomatic at early stages, which is the best time to detect it and intervene to prevent high mortality rates. Proper risk assessment, campaigns, and access to adequate healthcare need to be prioritised among patients at an early stage. Early detection of breast cancer can significantly improve the survival rate of breast cancer patients, since therapeutic strategies are more effective at this stage. Early detection of breast cancer can be achieved by developing devices that are simple, sensitive, low-cost, and employed at point-of-care (POC), especially in low-income countries (LICs). Nucleic-acid-based lateral flow assays (NABLFAs) that combine molecular detection with the immunochemical visualisation principles, have recently emerged as tools for disease diagnosis, even for low biomarker concentrations. Detection of circulating genetic biomarkers in non-invasively collected biological fluids with NABLFAs presents an appealing and suitable method for POC testing in resource-limited regions and/or LICs. Diagnosis of breast cancer at an early stage will improve the survival rates of the patients. This review covers the analysis of the current state of NABLFA technologies used in developing countries to reduce the scourge of breast cancer.

Effect of KRAS mutations and p53 expression on the postoperative prognosis of patients with colorectal cancer

Background

In the occurrence and development of colorectal cancer, p53 is an important regulator downstream of the MAPK signaling pathway and plays an important role in inhibiting abnormal proliferation signals generated by KRAS mutations. The purpose of this study is to explore the correlation between KRAS mutations and p53 expression and evaluate their prognosis values in colorectal cancer.

Methods

PCR technology and immunohistochemical (IHC) staining were used to detect KRAS mutation status and p53 expression level in 266 specimens of colorectal adenocarcinoma. Based on p53 expression level, these were divided into high expression and normal groups. Patients with KRAS mutations were divided into mutant and wild‐type groups. The two were combined with each other to analyze the relationship between patients' clinical data and their impact on the prognosis.

Results

KRAS mutations were found in 38.6% of the patients and 40.8% had a high p53 expression. There was no significant difference in the overall survival rate of patients, with or without KRAS gene mutations, and p53 expression level. In the group of patients with KRAS mutations, the survival time of patients with a high p53 expression was significantly lower than that of patients with a normal p53 expression (p = 0.020, log‐rank test). Multivariate analysis showed that p53 high expression is an independent risk factor for the overall survival time of patients with KRAS mutations (HR = 2.330, 95% CI = 1.041–5.216, p < 0.05).

Conclusion

Colorectal cancer patients with KRAS mutations with a high p53 expression have a poor prognosis.

How Surface-Enhanced Raman Spectroscopy Could Contribute to Medical Diagnoses

In the last decade, there has been a rapid increase in the number of surface-enhanced Raman scattering (SERS) spectroscopy applications in medical research. In this article we review some recent, and in our opinion, most interesting and promising applications of SERS spectroscopy in medical diagnostics, including those that permit multiplexing within the range important for clinical samples. We focus on the SERS-based detection of markers of various diseases (or those whose presence significantly increases the chance of developing a given disease), and on drug monitoring. We present selected examples of the SERS detection of particular fragments of DNA or RNA, or of bacteria, viruses, and disease-related proteins. We also describe a very promising and elegant ‘lab-on-chip’ approach used to carry out practical SERS measurements via a pad whose action is similar to that of a pregnancy test. The fundamental theoretical background of SERS spectroscopy, which should allow a better understanding of the operation of the sensors described, is also briefly outlined. We hope that this review article will be useful for researchers planning to enter this fascinating field.

2-Pyridin-4-yl-methylene-beta-boswellic Acid-A Potential Candidate for Targeting O6-Methylguanine-DNA Methyltransferase Epi-transcriptional Reprogramming in KRAS G13D-Microsatellite Stable, G12V-Microsatellite Instable Mutant Colon Cancer

PMBA (2-Pyridin-4-yl-methylene-beta-boswellic acid), screened from among the 21 novel series of semisynthetic analogues of β-boswellic acid, is being presented as a lead compound for integrative management of KRAS mutant colorectal cancer (CRC), upon testing and analysis for its anticancerous activity on a panel of NCI-60 cancer cell lines and in vivo models of the disease. PMBA (1.7-29 μM) exhibited potent proliferation inhibition on the cell lines and showed sensitivity in microsatellite instability and microsatellite stable (GSE39582 and GSE92921) subsets of KRAS gene (Kirsten rat sarcoma viral oncogene homolog)-mutated colon cell lines, as revealed via flow cytometry analysis. A considerable decrease in mitogen-activated protein kinase pathway downstream effectors was observed in the treated cell lines via the western blot and STRING (Search tool for the retrieval of interacting genes/proteins) analysis. PMBA was further found to target KRAS at its guanosine diphosphate site. Treatment of the cell lines with PMBA showed significant reduction in MGMT promoter methylation but restored MGMT (O⁶-methylguanine-DNA methyltransferase) messenger ribonucleic acid expression via significant demethylation of the hypermethylated CpG (Cytosine phosphate guanine) sites in the MGMT promoter. A significant decrease in dimethylated H3K9 (Dimethylation of lysine 9 on histone 3) levels in the MGMT promoter in DNA hypo- and hypermethylated HCT-116^G13D and SW-620^G12V cells was observed after treatment. In the MNU (N-methyl-N-nitrosourea)-induced CRC in vivo model, PMBA instillation restricted and repressed polyp formation, suppressed tumor proliferation marker Ki67 (Marker of proliferation), ablated KRAS-associated cytokine signaling, and decreased mortality. Clinical trial data for the parent molecule revealed its effectiveness against the disease, oral bioavailability, and system tolerance. Comprehensively, PMBA represents a new class of KRAS inhibitors having a therapeutic window in the scope of a drug candidate. The findings suggest that the PMBA analogue could inhibit the growth of human CRC in vivo through downregulation of cancer-associated biomarkers as well as reactivate expression of the MGMT gene associated with increased H3K9 acetylation and H3K4 methylation with facilitated transcriptional activation, which might be important in silencing of genes associated with upregulation in the activity of KRAS.

Integrative analysis of mutated genes and mutational processes reveals novel mutational biomarkers in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Recent studies have observed causative mutations in susceptible genes related to colorectal cancer in 10 to 15% of the patients. This highlights the importance of identifying mutations for early detection of this cancer for more effective treatments among high risk individuals. Mutation is considered as the key point in cancer research. Many studies have performed cancer subtyping based on the type of frequently mutated genes, or the proportion of mutational processes. However, to the best of our knowledge, combination of these features has never been used together for this task. This highlights the potential to introduce better and more inclusive subtype classification approaches using wider range of related features to enable biomarker discovery and thus inform drug development for CRC.

RESULTS

In this study, we develop a new pipeline based on a novel concept called 'gene-motif', which merges mutated gene information with tri-nucleotide motif of mutated sites, for colorectal cancer subtype identification. We apply our pipeline to the International Cancer Genome Consortium (ICGC) CRC samples and identify, for the first time, 3131 gene-motif combinations that are significantly mutated in 536 ICGC colorectal cancer samples. Using these features, we identify seven CRC subtypes with distinguishable phenotypes and biomarkers, including unique cancer related signaling pathways, in which for most of them targeted treatment options are currently available. Interestingly, we also identify several genes that are mutated in multiple subtypes but with unique sequence contexts.

CONCLUSION

Our results highlight the importance of considering both the mutation type and mutated genes in identification of cancer subtypes and cancer biomarkers. The new CRC subtypes presented in this study demonstrates distinguished phenotypic properties which can be effectively used to develop new treatments. By knowing the genes and phenotypes associated with the subtypes, a personalized treatment plan can be developed that considers the specific phenotypes associated with their genomic lesion.

Comparison of Next-Generation Sequencing and Polymerase Chain Reaction for Personalized Treatment-Related Genomic Status in Patients with Metastatic Colorectal Cancer

Personalized treatments based on the genetic profiles of tumors can simultaneously optimize efficacy and minimize toxicity, which is beneficial for improving patient outcomes. This study aimed to integrate gene alterations associated with predictive and prognostic outcomes in patients with metastatic colorectal cancer (mCRC) with polymerase chain reaction (PCR) and in-house next-generation sequencing (NGS) to detect KRAS, NRAS, and BRAF mutations. In the present study, 41 patients with mCRC were assessed between August 2017 and June 2019 at a single institution. The overall concordance between NGS and PCR results for detecting KRAS, NRAS, and BRAF mutations was considerably high (87.8-92.7%), with only 15 discrepant results between PCR and NGS. Our companion diagnostic test analyzes KRAS, NRAS, and BRAF as a panel of CRC molecular targets; therefore, it has the advantages of requiring fewer specimens and being more time and cost efficient than conventional testing for separate analyses, allowing for the simultaneous analysis of multiple genes.

Combination of artesunate and WNT974 induces KRAS protein degradation by upregulating E3 ligase ANACP2 and β-TrCP in the ubiquitin–proteasome pathway

Background

KRAS mutation is one of the dominant gene mutations in colorectal cancer (CRC). Up to present, targeting KRAS for CRC treatment remains a clinical challenge. WNT974 (LGK974) is a porcupine inhibitor that interferes Wnt signaling pathway. Artesunate (ART) is a water-soluble semi-synthetic derivative of artemisinin.

Methods

The synergistic effect of ART and WNT974 combination in reducing CRC cell viability was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. RT-PCR was utilized for the mRNA levels of KRAS, CUL7, ANAPC2, UBE2M, RNF123, SYVN1, or β-TrCP. Western blot assay was utilized for the protein levels of NRAS, HRAS, KRAS, ANAPC2, β-TrCP, GSK-3β, p-Akt (Ser473), t-Akt, p-PI3K (Tyr458), t-PI3K, p-mTOR (Ser2448), t-mTOR. Xenograft mouse model assay was performed for the anti-CRC effect of combination of ART and WNT974 in vivo. IHC assay was utilized for the levels of KRAS, β-TrCP, GSK-3β or ANAPC2 in tumor tissues.

Results

Our study shows that the combination of WNT974 and ART exhibits synergistic effect in reducing CRC growth. The combination treatment significantly reduces KRAS protein level and activity in CRC cells. Interestingly, the combination treatment increases E3 ligases ANAPC2 expression. Our data show that overexpression of ANAPC2 significantly reduces KRAS protein levels, which is reversed by MG132. Knockdown of ANAPC2 in CRC abolishes the combination treatment-reduce KRAS expression. Besides, the treatment also increases the expressions of GSK-3β and E3 ligase β-TrCP that is known to degrade GSK-3β-phosphorylated KRAS protein. Knockdown of β-TrCP- and inhibition of GSK-3β abolish the combination treatment-induce KRAS ubiquitination and reduction in expression. Last but not least, combination treatment suppresses PI3K/Akt/m-TOR signaling pathway.

Conclusions

Our data clearly show that the combination treatment significantly enhances KRAS protein degradation via the ubiquitination ubiquitin–proteasome pathway, which is also demonstrated in xenograft mouse model. The study provides strong scientific evidence for the development of the combination of WNT974 and ART as KRAS-targeting therapeutics for CRC treatment.

Neoantigen: A Promising Target for the Immunotherapy of Colorectal Cancer

At present, there are various treatment strategies for colorectal cancer, including surgery, chemotherapy, radiotherapy, and targeted therapy. In recent years, with the continuous development of immunotherapy, immune checkpoint inhibitors (ICIs) can significantly improve the treatment of advanced colorectal cancer patients with high levels of microsatellite instability. In addition to ICIs, neoantigens, as a class of tumor-specific antigens (TSA), are regarded as new immunotherapy targets for many cancer species and are being explored for antitumor therapy. Immunotherapy strategies based on neoantigens include tumor vaccines and adoptive cell therapy (ACT). These methods aim to eliminate tumor cells by enhancing the immune response of host T-cells to neoantigens. In addition, for MSS colorectal cancer, such “cold tumors” with low mutation rates and stable microsatellites are not sensitive to ICIs, whereas neoantigens could provide a promising immunotherapeutic avenue. In this review, we summarized the current status of colorectal cancer neoantigen prediction and current clinical trials of neoantigens and discussed the difficulties and limitations of neoantigens-based therapies for the treatment of CRC.

Current Perspectives on the Importance of Pathological Features in Prognostication and Guidance of Adjuvant Chemotherapy in Colon Cancer

There is not a clear consensus on which pathological features and biomarkers are important in guiding prognosis and adjuvant therapy in colon cancer. The Pathology in Colon Cancer, Prognosis and Uptake of Adjuvant Therapy (PiCC UP) Australia and New Zealand questionnaire was distributed to colorectal surgeons, medical oncologists and pathologists after institutional board approval. The aim of this study was to understand current specialist attitudes towards pathological features in the prognostication of colon cancer and adjuvant therapy in stage II disease. A 5-scale Likert score was used to assess attitudes towards 23 pathological features for prognosis and 18 features for adjuvant therapy. Data were analysed using a rating scale and graded response model in item response theory (IRT) on STATA (Stata MP, version 15; StataCorp LP). One hundred and sixty-four specialists (45 oncologists, 86 surgeons and 33 pathologists) participated. Based on IRT modelling, the most important pathological features for prognosis in colon cancer were distant metastases, lymph node metastases and liver metastases. Other features seen as important were tumour rupture, involved margin, radial margin, CRM, lymphovascular invasion and grade of differentiation. Size of tumour, location, lymph node ratio and EGFR status were considered less important. The most important features in decision making for adjuvant therapy in stage II colon cancer were tumour rupture, lymphovascular invasion and microsatellite instability. BRAF status, size of tumour, location, tumour budding and tumour infiltrating lymphocytes were factored as lesser importance. Biomarkers such as CDX2, EGFR, KRAS and BRAF status present areas for further research to improve precision oncology. This study provides the most current status on the importance of pathological features in prognostication and recommendations for adjuvant therapy in Australia and New Zealand. Results of this nationwide study may be useful to help in guiding prognosis and adjuvant treatment in colon cancer.

KRAS as a Modulator of the Inflammatory Tumor Microenvironment: Therapeutic Implications

KRAS mutations are one of the most frequent oncogenic mutations of all human cancers, being more prevalent in pancreatic, colorectal, and lung cancers. Intensive efforts have been encouraged in order to understand the effect of KRAS mutations, not only on tumor cells but also on the dynamic network composed by the tumor microenvironment (TME). The relevance of the TME in cancer biology has been increasing due to its impact on the modulation of cancer cell activities, which can dictate the success of tumor progression. Here, we aimed to clarify the pro- and anti-inflammatory role of KRAS mutations over the TME, detailing the context and the signaling pathways involved. In this review, we expect to open new avenues for investigating the potential of KRAS mutations on inflammatory TME modulation, opening a different vision of therapeutic combined approaches to overcome KRAS-associated therapy inefficacy and resistance in cancer.

Pathological Features and Prognostication in Colorectal Cancer

The prognostication of colorectal cancer (CRC) has traditionally relied on staging as defined by the Union for International Cancer Control (UICC) and American Joint Committee on Cancer (AJCC) TNM staging classifications. However, clinically, there appears to be differences in survival patterns independent of stage, suggesting a complex interaction of stage, pathological features, and biomarkers playing a role in guiding prognosis, risk stratification, and guiding neoadjuvant and adjuvant therapies. Histological features such as tumour budding, perineural invasion, apical lymph node involvement, lymph node yield, lymph node ratio, and molecular features such as MSI, KRAS, BRAF, and CDX2 may assist in prognostication and optimising adjuvant treatment. This study provides a comprehensive review of the pathological features and biomarkers that are important in the prognostication and treatment of CRC. We review the importance of pathological features and biomarkers that may be important in colorectal cancer based on the current evidence in the literature.

Case Report: The Added Value of Liquid Biopsy in Advanced Colorectal Cancer From Clinical Case Experiences

Liquid biopsy represents a valid strategy for tumor molecular characterization. It gives the opportunity to bypass tumor heterogeneity, to monitor tumor characteristics during the course of treatment, and to perform the analysis even when tumor tissue is not available or inadequate. In the clinical practice of metastatic colorectal cancer, tumor molecular characterization is crucial for patient management, as RAS and BRAF status could influence the treatment choice. Although for this type of cancer tumor tissue is usually available at diagnosis, liquid biopsy could give complementary information and could permit monitoring of the mutation status during the course of treatment. At present, there are no clinical indications for its use in clinical practice. However, we report four clinical cases for which liquid biopsy analysis gave integrative information with respect to tumor tissue characterization, which permits us to understand the unresponsiveness of patients to treatment, with potential implications in patient's management.

KRAS mutations in patients with colorectal cancer in Libya

Large prospective clinical trials have demonstrated that colorectal cancers (CRCs) with wild-type KRAS respond favorably to anti-epidermal growth factor receptor treatment, thus making mutational analysis obligatory prior to treatment. In our study, frozen CRC tissues from Libyan patients were analyzed for KRAS and HRAS mutations in codons 12/13 by direct sequencing and the correlations with clinical and pathological parameters were investigated. A total of 34 CRC cases, comprising 19 men and 15 women (age range, 24-87 years), were subjected to systematic analysis for RAS mutations. Although HRAS mutations were not detected in any of the patients in the study group, KRAS codon 12/13 mutations were present in 38.2% (13/34) of the patients. The frequent types of codon 12 mutations were glycine to aspartate (G12D, 46.1%); glycine to valine (G12V, 30.8%) and glycine to cysteine (G12C, 15.4%), while the codon 13 mutations were glycine to aspartate (G13D, 7.7%). G→A mutations occurred in 53.8% (7/13) of the patients, while G→T mutations occurred in 46.2% (6/13) of the patients. Mutations occurred at the first base of codon 12 or 13 in 2/13 (15.4%) and at the second base in 11/13 (84.6%) patients. There was no significant association between clinicopathological characteristics and KRAS mutation status, except the site of the tumors harboring KRAS mutations, which was as follows: The frequency was higher among tumors located in the left colon (8/13, 61.5%) compared to other sites (P=0.027). KRAS mutations were correlated with advanced age, with 10/13 being aged >50 years and affected 8/15 female patients (53%) compared with 5/19 male patients (26%). The highest frequency of KRAS mutations was observed in highly differentiated CRCs (8/13).

Therapeutic effect of curcumin in gastrointestinal cancers: A comprehensive review

Gastrointestinal (GI) cancers with a high global prevalence are a leading cause of morbidity and mortality. Accordingly, there is a great need to develop efficient therapeutic approaches. Curcumin, a naturally occurring agent, is a promising compound with documented safety and anticancer activities. Recent studies have demonstrated the activity of curcumin in the prevention and treatment of different cancers. According to systematic studies on curcumin use in various diseases, it can be particularly effective in GI cancers because of its high bioavailability in the gastrointestinal tract. Nevertheless, the clinical applications of curcumin are largely limited because of its low solubility and low chemical stability in water. These limitations may be addressed by the use of relevant analogues or novel delivery systems. Herein, we summarize the pharmacological effects of curcumin against GI cancers. Moreover, we highlight the application of curcumin's analogues and novel delivery systems in the treatment of GI cancers.

BMAL1 Knockdown Leans Epithelial-Mesenchymal Balance toward Epithelial Properties and Decreases the Chemoresistance of Colon Carcinoma Cells

The circadian clock coordinates biological and physiological functions to day/night cycles. The perturbation of the circadian clock increases cancer risk and affects cancer progression. Here, we studied how BMAL1 knockdown (BMAL1-KD) by shRNA affects the epithelial-mesenchymal transition (EMT), a critical early event in the invasion and metastasis of colorectal carcinoma (CRC). In corresponding to a gene set enrichment analysis, which showed a significant enrichment of EMT and invasive signatures in BMAL1_high CRC patients as compared to BMAL1_low CRC patients, our results revealed that BMAL1 is implicated in keeping the epithelial-mesenchymal equilibrium of CRC cells and influences their capacity of adhesion, migration, invasion, and chemoresistance. Firstly, BMAL1-KD increased the expression of epithelial markers (E-cadherin, CK-20, and EpCAM) but decreased the expression of Twist and mesenchymal markers (N-cadherin and vimentin) in CRC cell lines. Finally, the molecular alterations after BMAL1-KD promoted mesenchymal-to-epithelial transition-like changes mostly appeared in two primary CRC cell lines (i.e., HCT116 and SW480) compared to the metastatic cell line SW620. As a consequence, migration/invasion and drug resistance capacities decreased in HCT116 and SW480 BMAL1-KD cells. Together, BMAL1-KD alerts the delicate equilibrium between epithelial and mesenchymal properties of CRC cell lines, which revealed the crucial role of BMAL1 in EMT-related CRC metastasis and chemoresistance.

Development of a nanotechnology-based approach for capturing and detecting nucleic acids by using flow cytometry

Nucleic acid-based molecular diagnosis has gained special importance for the detection and early diagnosis of genetic diseases as well as for the control of infectious disease outbreaks. The development of systems that allow for the detection and analysis of nucleic acids in a low-cost and easy-to-use way is of great importance. In this context, we present a combination of a nanotechnology-based approach with the already validated dynamic chemical labeling (DCL) technology, capable of reading nucleic acids with single-base resolution. This system allows for the detection of biotinylated molecular products followed by simple detection using a standard flow cytometer, a widely used platform in clinical and molecular laboratories, and therefore, is easy to implement. This proof-of-concept assay has been developed to detect mutations in KRAS codon 12, as these mutations are highly important in cancer development and cancer treatments.

K-Ras Peptide Mimotope Induces Antigen Specific Th1 and B-Cell Immune Responses against G12A-Mutated K-Ras Antigen in Balb/c Mice

KRAS G12A somatic point mutation in adenocarcinomas is categorized clinically as ineligibility criteria for anti-epidermal growth factor receptor (EGFR) monoclonal antibody therapies. In this study, a modified G12A-K-ras epitope (139A) with sequence-specific modifications to improve immunogenicity was developed as a potential vaccine against G12A-mutant KRAS cancers. Additionally, coupling of the 139A epitope with a tetanus toxoid (TTD) universal T-cell epitope to improve antigenicity was also reported. To facilitate convenient oral administration, Lactococcus lactis, which possesses innate immunomodulatory properties, was chosen as a live gastrointestinal delivery vehicle. Recombinant L. lactis strains secreting a G12A mutated K-ras control and 139A with and without TTD fusion were generated for comparative immunogenicity assessment. BALB/c mice were immunized orally, and high survivability of L. lactis passage through the gastrointestinal tract was observed. Elevations in B-cell count with a concomitant titre of antigen-specific IgG and interferon-γ secreting T-cells were observed in the 139A treated mice group. Interestingly, an even higher antigen-specific IgA response and interferon-γ secreting T-cell counts were observed in 139A-TTD mice group upon re-stimulation with the G12A mutated K-ras antigen. Collectively, these results indicated that an antigen-specific immune response was successfully stimulated by 139A-TTD vaccine, and a TTD fusion was successful in further enhancing the immune responses.

Reg4 and its downstream transcriptional activator CD44ICD in stage II and III colorectal cancer

Reg4 is highly expressed in gastrointestinal malignancies and acts as a mitogenic and pro-invasive factor. Our recent works suggest that Reg4 binds with CD44 and induces its proteolytic cleavage to release intra-cytoplasmic domain of CD44 (CD44ICD). The goal of this study is to demonstrate clinical significance of the Reg4-CD44/CD44ICD pathway in stage II/III colon cancer and its association with clinical parameters of aggression. We constructed a tissue microarray (TMA) of 93 stage II/III matched colon adenocarcinoma patients, 23 with recurrent disease. The TMA was immunohistochemically stained for Reg4, CD44, and CD44ICD proteins and analyzed to identify associations with tumor characteristics, recurrence and overall survival. The TMA data analysis showed a significant correlation between Reg4 and CD44 (r² = 0.23, P = 0.028), CD44 and CD44ICD (r² = 0.36, p = 0.0004), and Reg4 and CD44ICD (r² = 0.45, p ≤ 0.0001). Reg4 expression was associated with larger tumor size (r² = 0.23, p = 0.026). Although, no association was observed between Reg4, CD44, or CD44ICD expression and disease recurrence, Reg4-positive patients had a median survival of 4 years vs. 7 years for Reg4-negative patients (p = 0.04) in patients who recurred. Inhibition of the Reg4-CD44/CD44ICD pathway may be a future therapeutic target for colon cancer patients.

GUCY2C as a biomarker to target precision therapies for patients with colorectal cancer

Introduction

Colorectal cancer (CRC) is one of the most-deadly malignancies worldwide. Current therapeutic regimens for CRC patients are relatively generic, based primarily on disease type and stage, with little variation. As the field of molecular oncology advances, so too must therapeutic management of CRC. Understanding molecular heterogeneity has led to a new-found promotion for precision therapy in CRC; underlining the diversity of molecularly targeted therapies based on individual tumor characteristics.

Areas covered

We review current approaches for the treatment of CRC and discuss the potential of precision therapy in advanced CRC. We highlight the utility of the intestinal protein guanylyl cyclase C (GUCY2C), as a multi-purpose biomarker and unique therapeutic target in CRC. Here, we summarize current GUCY2C-targeted approaches for treatment of CRC.

Expert opinion

The GUCY2C biomarker has multi-faceted utility in medicine. Developmental investment of GUCY2C as a diagnostic and therapeutic biomarker offers a variety of options taking the molecular characteristics of cancer into account. From GUCY2C-targeted therapies, namely cancer vaccines, CAR-T cells, and monoclonal antibodies, to GUCY2C agonists for chemoprevention in those who are at high risk for developing colorectal cancer, the utility of this protein provides many avenues for exploration with significance in the field of precision medicine.

Effect of Cetuximab-Conjugated Gold Nanoparticles on the Cytotoxicity and Phenotypic Evolution of Colorectal Cancer Cells

Epidermal growth factor receptor (EGFR) is estimated to be overexpressed in 60~80% of colorectal cancer (CRC), which is associated with a poor prognosis. Anti-EGFR targeted monoclonal antibodies (cetuximab and panitumumab) have played an important role in the treatment of metastatic CRC. However, the therapeutic response of anti-EGFR monoclonal antibodies is limited due to multiple resistance mechanisms. With the discovery of new functions for gold nanoparticles (AuNPs), we hypothesize that cetuximab-conjugated AuNPs (cetuximab-AuNPs) will not only improve the cytotoxicity for cancer cells, but also introduce expression change of the related biomarkers on cancer cell surface. In this contribution, we investigated the size-dependent cytotoxicity of cetuximab-AuNPs to CRC cell line (HT-29), while also monitored the expression of cell surface biomarkers in response to treatment with cetuximab and cetuximab-AuNPs. AuNPs with the size of 60 nm showed the highest impact for cell cytotoxicity, which was tested by cell counting kit-8 (CCK-8) assay. Three cell surface biomarkers including epithelial cell adhesion molecule (EpCAM), melanoma cell adhesion molecule (MCAM), and human epidermal growth factor receptor-3 (HER-3) were found to be expressed at higher heterogeneity when cetuximab was conjugated to AuNPs. Both surface-enhanced Raman scattering/spectroscopy (SERS) and flow cytometry demonstrated the correlation of cell surface biomarkers in response to the drug treatment. We thus believe this study provides powerful potential for drug-conjugated AuNPs to enhance cancer prognosis and therapy.

Clinical features and KRAS mutation in colorectal cancer with bone metastasis

Bone metastasis is known as a poor prognostic factor in colorectal cancer (CRC), but its clinical manifestations and outcomes are uncertain. CRC with bone metastasis was searched from January 2006 to April 2016. Of 11,551 CRC patients, 321 (2.7%) patients had bone metastasis. Bone-only metastasis was found in only 8.7% of patients. Synchronous bone metastasis was present in 147 (45.8%) patients. In patients with metachronous bone metastasis, the median time from CRC diagnosis to bone metastasis (TTB) was 27.2 months. KRAS mutation status was a marginally significant factor affecting TTB (median TTB, KRAS wild-type or mutation: 29 or 25.8 months, respectively, P = 0.068). Skeletal-related events (SREs) were noted in 200 (62.3%) patients. Median overall survival (OS) from diagnosis of bone metastasis was 8.0 months. On multivariate analysis, multi-organ metastasis, peritoneal metastasis, neutrophil-to-lymphocyte ratio (NLR) ≥ 2.7, and alkaline phosphatase (ALP) ≥ 123 were independent factors for OS. Palliative chemotherapy prolonged survival in CRC patients with bone metastasis (HR 0.25, 95% CI 0.2–0.33). In conclusion, bone metastasis of CRC is rare, but it is related to SREs. Most patients have other organ metastasis and survival is 8.0 months. Attention should be paid to bone metastasis in CRC patients.

Structure of two G-quadruplexes in equilibrium in the KRAS promoter

KRAS is one of the most mutated oncogenes and still considered an undruggable target. An alternative strategy would consist in targeting its gene rather than the protein, specifically the formation of G-quadruplexes (G4) in its promoter. G4 are secondary structures implicated in biological processes, which can be formed among G-rich DNA (or RNA) sequences. Here we have studied the major conformations of the commonly known KRAS 32R, or simply 32R, a 32 residue sequence within the KRAS Nuclease Hypersensitive Element (NHE) region. We have determined the structure of the two major stable conformers that 32R can adopt and which display slow equilibrium (>ms) with each other. By using different biophysical methods, we found that the nucleotides G9, G25, G28 and G32 are particularly implicated in the exchange between these two conformations. We also showed that a triad at the 3' end further stabilizes one of the G4 conformations, while the second conformer remains more flexible and less stable.

Modeling Adaptive Resistance of KRAS Mutant Colorectal Cancer to MAPK Pathway Inhibitors with a Three-Dimensional Tumor Model

Single-agent drug treatment of KRAS^mut colorectal cancers is often ineffective because the activation of compensatory signaling pathways leads to drug resistance. To mimic cyclic chemotherapy treatments of patients, we showed that intermittent treatments of 3D tumor spheroids of KRAS^mut colorectal cancer cells with inhibitors of mitogen-activated protein kinase (MAPK) signaling pathway temporarily suppressed growth of spheroids. However, the efficacy of successive single-agent treatments was significantly reduced. Molecular analysis showed compensatory activation of PI3K/AKT and STAT kinases and EGFR family proteins. To overcome the adaptation of cancer cells to MAPK pathway inhibitors, we treated tumor spheroids with a combination of MEK and EGFR inhibitors. This approach significantly blocked signaling of MAPK and PI3K/AKT pathways and prevented the growth of spheroids, but it was not effective against STAT signaling. Although the combination treatment blocked the matrix invasion of DLD1 cells, additional treatments with STAT inhibitors were necessary to prevent invasiveness of HCT116 cells. Overall, our drug resistance model elucidated the mechanisms of treatment-induced growth and invasiveness of cancer cells and allowed design-driven testing and identifying of effective treatments to suppress these phenotypes.

Inferring tumor progression in large datasets

Identification of mutations of the genes that give cancer a selective advantage is an important step towards research and clinical objectives. As such, there has been a growing interest in developing methods for identification of driver genes and their temporal order within a single patient (intra-tumor) as well as across a cohort of patients (inter-tumor). In this paper, we develop a probabilistic model for tumor progression, in which the driver genes are clustered into several ordered driver pathways. We develop an efficient inference algorithm that exhibits favorable scalability to the number of genes and samples compared to a previously introduced ILP-based method. Adopting a probabilistic approach also allows principled approaches to model selection and uncertainty quantification. Using a large set of experiments on synthetic datasets, we demonstrate our superior performance compared to the ILP-based method. We also analyze two biological datasets of colorectal and glioblastoma cancers. We emphasize that while the ILP-based method puts many seemingly passenger genes in the driver pathways, our algorithm keeps focused on truly driver genes and outputs more accurate models for cancer progression.

Cancer is a disease caused by the accumulation of somatic mutations in the genome. This process is mainly driven by mutations in certain genes that give the harboring cells some selective advantage. The rather few driver genes are usually masked amongst an abundance of so-called passenger mutations. Identification of the driver genes and the temporal order in which the mutations occur is of great importance towards research and clinical objectives. In this paper, we introduce a probabilistic model for cancer progression and devise an efficient inference algorithm to train the model. We show that our method scales favorably to large datasets and provides superior performance compared to an ILP-based counterpart on a wide set of synthetic data simulations. Our Bayesian approach also allows for systematic model selection and confidence quantification procedures in contrast to the previous non-probabilistic progression models. We also study two large datasets on colorectal and glioblastoma cancers and validate our inferred model in comparison to the ILP-based method.

KRAS and PIK3CA bi-mutations predict a poor prognosis in colorectal cancer patients: A single-site report

Study rationale

The coexistence of KRAS and PIK3CA mutations in cells implies potential synergistic hyperactivation of the Ras/MAPK and PI3K/Akt oncogenic pathways. Therefore, it is desirable to investigate the concomitant mutations of KRAS and PIK3CA in colorectal cancer (CRC) samples and whether the concomitant mutations are associated with a poor prognosis in CRC patients.

Aim

To investigate the clinicpathological characteristics and prognostic value of concomitant mutations of KRAS and PIK3CA in CRC samples.

Methods

In this study, a total of 655 CRC patients from the Sixth Affiliated Hospital of Sun Yat-sen University were enrolled from January to December 2015. Sanger sequencing was applied to survey the mutational status of hotspot regions in the open reading frames (ORFs) of the KRAS and PIK3CA genes. Clinicpathological parameters were collected and analyzed. The Kaplan-Meier method and Cox regression model were applied to determine the correlation between the KRAS and PIK3CA mutation statuses and survival.

Results

We found that KRAS and PIK3CA bi-mutations were significantly associated with aggressive clinicpathological features. Among the studied CRC patients, those with either KRAS mutations (P = 0.004) or KRAS and PIK3CA bi-mutations (P = 0.033) had poor overall survival (OS). In the multivariable analysis, KRAS mutations in exons 3 and 4 but not exon 2 with concomitant PIK3CA mutations were associated with a high risk of death (univariate HR = 8.05; 95% CI, 1.926–33.64, P = 0.004; multivariate HR = 10.505; 95% CI, 2.304–47.905, P = 0.002).

Conclusion

The concomitant mutation statuses of KRAS and PIK3CA should be considered when the prognostic value of gene mutations is consulted in CRC patients.

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.

IGF-1R inhibition induces MEK phosphorylation to promote survival in colon carcinomas

The insulin-like growth factor 1 receptor (IGF-1R) governs several signaling pathways for cell proliferation, survival, and anti-apoptosis. Thus, targeting IGF-1R appears as a reasonable rationale for tumor treatment. However, clinical studies showed that inhibition of IGF-1R has very limited efficacy due to the development of resistance to IGF-1R blockade in tumor cells. Here, we discovered that prolonged treatment of colon cancer cells with IGF-1R inhibitors (BMS-754807 and GSK1838705A) stimulates p70 KDa ribosomal protein S6 kinase 1 (p70S6K1) activation, a well-known kinase signaling for cell survival. We also found that p70S6K1 activation by IGF-1R inhibition is independent of K-Ras and PIK3CA mutations that frequently occur in colon cancer. Besides the increased p70S6K1 phosphorylation, the phosphorylation of mitogen-activated protein kinase kinase 1 and 2 (MEK1/2) was elevated in the cells treated with BMS-754807. Interestingly, the increases in MEK1/2 and p70S6K1 phosphorylation were also observed when cells were subjected to the treatment of AKT inhibitor or genetic knockdown of AKT2 but not AKT1, suggesting that AKT2 inhibition stimulates MEK1/2 phosphorylation to activate p70S6K1. Conversely, inhibition of MEK1/2 by MEK1/2 inhibitor (U0126) or knockdown of MEK1 and MEK2 by corresponding mek1 and mek2 siRNA enhanced AKT phosphorylation, indicating mutual inhibition between AKT and MEK. Furthermore, the combination of BMS-754807 and U0126 efficiently decreased the cell viability and increased cleaved caspase 3 and apoptosis in vitro and in vivo. Our data suggest that the treatment of colon tumor cells with IGF-1R inhibitors stimulates p70S6K1 activity via MEK1/2 to promote survival, providing a new strategy for colorectal cancer therapeutics.

Multiplex detection of ctDNA mutations in plasma of colorectal cancer patients by PCR/SERS assay

Molecular diagnostic testing of KRAS and BRAF mutations has become critical in the management of colorectal cancer (CRC) patients. Some progress has been made in liquid biopsy detection of mutations in circulating tumor DNA (ctDNA), which is a fraction of circulating cell-free DNA (cfDNA), but slow analysis for DNA sequencing methods has limited rapid diagnostics. Other methods such as quantitative PCR and more recently, droplet digital PCR (ddPCR), have limitations in multiplexed capacity and the need for expensive specialized equipment. Hence, a robust, rapid and facile strategy is needed for detecting multiple ctDNA mutations to improve the management of CRC patients. To address this significant problem, herein, we propose a new application of multiplex PCR/SERS (surface-enhanced Raman scattering) assay for the detection of ctDNA in CRC, in a fast and non-invasive manner to diagnose and stratify patients for effective treatment.

Methods: To discriminate ctDNA mutations from wild-type cfDNA, allele-specific primers were designed for the amplification of three clinically important DNA point mutations in CRC including KRAS G12V, KRAS G13D and BRAF V600E. Surface-enhanced Raman scattering (SERS) nanotags were labelled with a short and specific sequence of oligonucleotide, which can hybridize with the corresponding PCR amplicons. The PCR/SERS assay was implemented by firstly amplifying the multiple mutations, followed by binding with multicolor SERS nanotags specific to each mutation, and subsequent enrichment with magnetic beads. The mutation status was evaluated using a portable Raman spectrometer where the fingerprint spectral peaks of the corresponding SERS nanotags indicate the presence of the mutant targets. The method was then applied to detect ctDNA from CRC patients under a blinded test, the results were further validated by ddPCR.

Results: The PCR/SERS strategy showed high specificity and sensitivity for genotyping CRC cell lines and plasma ctDNA, where as few as 0.1% mutant alleles could be detected from a background of abundant wild-type cfDNA. The blinded test using 9 samples from advanced CRC patients by PCR/SERS assay was validated with ddPCR and showed good consistency with pathology testing results.

Conclusions: With ddPCR-like sensitivity yet at the convenience of standard PCR, the proposed assay shows great potential in sensitive detection of multiple ctDNA mutations for clinical decision-making.

Association of RAS Mutation Location and Oncologic Outcomes After Resection of Colorectal Liver Metastases

BACKGROUND

RAS mutations are prognostic for patients with metastatic colorectal cancer (mCRC). We investigated clinical, pathologic, and survival differences based on RAS exon for patients with colorectal liver metastases (CRLM).

METHODS

This retrospective, single-center study included patients with R0/R1 resection of CRLM from 1992 to 2016. Patients with unresected extrahepatic disease or liver-first resection were excluded. Overall survival (OS) and recurrence-free survival were assessed and stratified by mutation status and location. Fisher's exact test, Wilcoxon rank-sum test, and log-rank test were used, where appropriate.

RESULTS

A total of 938 mCRC patients were identified with median age of 57 (range 19-91). Of the 445 patients with KRAS mutations, 407 (91%) had a mutation in exon 2, 14 (3%) exon 3, and 24 (5%) exon 4. Median OS was 71.4 months (95% confidence interval [CI] 66.1-76.5). Patients with KRAS mutations had worse OS compared with KRAS wild-type patients (median 55.5 vs. 91.3 months, p < 0.001). While there was no significant difference in OS based on the exon mutated (p = 0.12), 5-year OS was higher for patients with exon 4 mutations [68.8% (95% CI 0.45-0.84)] compared with those with mutations in exon 2 [45.7% (95% CI 0.40-0.51)] or exon 3 [39.1% (95% CI: 0.11-0.68)]. Patients with NRAS mutant tumors also had worse OS compared with NRAS wild-type patients (median 50.9 vs. 73.3 months, p = 0.03).

CONCLUSIONS

NRAS and KRAS exon 3/4 mutations are present in a minority of mCRC patients. Patients with exon 4 mutant tumors may have a more favorable prognosis, although the difference in oncologic outcomes based on mutated exon appears to be smaller than previously reported.

Cytotoxicity study of the interleukin-12-expressing recombinant Newcastle disease virus strain, rAF-IL12, towards CT26 colon cancer cells in vitro and in vivo

Background

Oncolytic viruses have emerged as an alternative therapeutic modality for cancer as they can replicate specifically in tumour cells and induce toxic effects leading to apoptosis. Despite the great potentials and promising results shown in multiple studies, it appears that their efficacy is still moderate and deemed as not sufficient in clinical studies. In addressing this issue, genetic/molecular engineering approach has paved its way to improve the therapeutic efficacy as observed in the case of herpes simplex virus (HSV) expressing granulocyte–macrophage colony-stimulating factor (GM-CSF). This study aimed to explore the cytotoxicity effects of recombinant NDV strain AF2240-i expressing interleukin-12 (rAF-IL12) against CT26 colon cancer cells.

Methods

The cytotoxicity effect of rAF-IL12 against CT26 colon cancer cell line was determined by MTT assay. Based on the IC₅₀ value from the anti-proliferative assay, further downward assays such as Annexin V FITC and cell cycle progression were carried out and measured by flow cytometry. Then, the in vivo study was conducted where the rAF-IL12 viral injections were given at the intra-tumoral site of the CT26 tumour-burden mice. At the end of the experiment, serum biochemical, T cell immunophenotyping, serum cytokine, histopathology of tumour and organ section, TUNEL assay, and Nanostring gene expression analysis were performed.

Results

The rAF-IL12 induced apoptosis of CT26 colon cancer cells in vitro as revealed in the Annexin V FITC analysis and also arrested the cancer cells progression at G₁ phase of the cell cycle analysis. On the other hand, the rAF-IL12 significantly (p < 0.05) inhibited the growth of CT26 tumour in Balb/c mice and had regulated the immune system by increasing the level of CD4 + , CD8 + , IL-2, IL-12, and IFN-γ. Furthermore, the expression level of apoptosis-related genes (bax and p53) was up-regulated as a result of the rAF-IL12 treatment. Additionally, the rAF-IL12 had also down-regulated the expression level of KRAS, BRAF, MAPK1, Notch1, CCL2, and VEGF oncogenes. Besides, rAF-IL12 intra-tumoral delivery was considered safe and not hazardous to the host as evidenced in pathophysiology of the normal tissues and organs of the mice as well as from the serum biochemistry profile of liver and kidney.

Conclusions

These results indicated that rAF-IL12 had better anti-tumoral and cytotoxicity effects compared to its parental wild-type, AF2240-i in combatting the CT26 colon cancer model.

Prognostic value of KRAS mutation status in colorectal cancer patients: a population-based competing risk analysis

Background

To use competing analyses to estimate the prognostic value of KRAS mutation status in colorectal cancer (CRC) patients and to build nomogram for CRC patients who had KRAS testing.

Method

The cohort was selected from the Surveillance, Epidemiology, and End Results database. Cumulative incidence function model and multivariate Fine-Gray regression for proportional hazards modeling of the subdistribution hazard (SH) model were used to estimate the prognosis. An SH model based nomogram was built after a variable selection process. The validation of the nomogram was conducted by discrimination and calibration with 1,000 bootstraps.

Results

We included 8,983 CRC patients who had KRAS testing. SH model found that KRAS mutant patients had worse CSS than KRAS wild type patients in overall cohort (HR = 1.10 (95% CI [1.04–1.17]), p < 0.05), and in subgroups that comprised stage III CRC (HR = 1.28 (95% CI [1.09–1.49]), p < 0.05) and stage IV CRC (HR = 1.14 (95% CI [1.06–1.23]), p < 0.05), left side colon cancer (HR = 1.28 (95% CI [1.15–1.42]), p < 0.05) and rectal cancer (HR = 1.23 (95% CI [1.07–1.43]), p < 0.05). We built the SH model based nomogram, which showed good accuracy by internal validation of discrimination and calibration. Calibration curves represented good agreement between the nomogram predicted CRC caused death and actual observed CRC caused death. The time dependent area under the curve of receiver operating characteristic curves (AUC) was over 0.75 for the nomogram.

Conclusion

This is the first population based competing risk study on the association between KRAS mutation status and the CRC prognosis. The mutation of KRAS indicated a poor prognosis of CRC patients. The current competing risk nomogram would help physicians to predict cancer specific death of CRC patients who had KRAS testing.

Metabolic characterization of colorectal cancer cells harbouring different KRAS mutations in codon 12, 13, 61 and 146 using human SW48 isogenic cell lines

INTRODUCTION

Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) mutations occur in approximately one-third of colorectal (CRC) tumours and have been associated with poor prognosis and resistance to some therapeutics. In addition to the well-documented pro-tumorigenic role of mutant Ras alleles, there is some evidence suggesting that not all KRAS mutations are equal and the position and type of amino acid substitutions regulate biochemical activity and transforming capacity of KRAS mutations.

OBJECTIVES

To investigate the metabolic signatures associated with different KRAS mutations in codons 12, 13, 61 and 146 and to determine what metabolic pathways are affected by different KRAS mutations.

METHODS

We applied an NMR-based metabonomics approach to compare the metabolic profiles of the intracellular extracts and the extracellular media from isogenic human SW48 CRC cell lines with different KRAS mutations in codons 12 (G12D, G12A, G12C, G12S, G12R, G12V), 13 (G13D), 61 (Q61H) and 146 (A146T) with their wild-type counterpart. We used false discovery rate (FDR)-corrected analysis of variance (ANOVA) to determine metabolites that were statistically significantly different in concentration between the different mutants.

RESULTS

CRC cells carrying distinct KRAS mutations exhibited differential metabolic remodelling, including differences in glycolysis, glutamine utilization and in amino acid, nucleotide and hexosamine metabolism.

CONCLUSIONS

Metabolic differences among different KRAS mutations might play a role in their different responses to anticancer treatments and hence could be exploited as novel metabolic vulnerabilities to develop more effective therapies against oncogenic KRAS.

An enzymatic on/off switch-mediated assay for KRAS hotspot point mutation detection of circulating tumor DNA

Background

To detect the mutations of KRAS gene in colorectal cancer patients and other cancer patients, it is of value to develop non‐invasive, sensitive, specific, easy, and low‐cost assays.

Methods

Templates harboring hotspot mutations of the KRAS gene were constructed, and primers were designed for evaluation of the specificity, and sensitivity of detection system consisted of exonuclease polymerase‐mediated on/off switch; then, gel electrophoresis and real‐time PCR were performed for verification. The assay was verified by testing the DNA pool of normal controls and circulating DNA (ctDNA) samples from 14 tumor patients, as compared to Sanger sequencing.

Results

A specific and sensitive assay consisted of exonuclease polymerase‐mediated on/off switch, and multiplex real‐time PCR method has been established. This assay could detect <100 copies of KRAS mutation in more than 10 million copies of wild‐type KRAS gene fragments. This assay was applied to test KRAS gene mutations in three cases of fourteen ctDNA samples, and the results were consistent with Sanger sequencing. However, this PCR‐based assay was more sensitive and easier to be interpreted.

Conclusion

This assay can detect the presence of KRAS hotspot mutations in clinical circulating tumor DNA samples. The assay has a potential to be used in early diagnosis of colorectal cancer as well as other types of cancer.

Disparity between Inter-Patient Molecular Heterogeneity and Repertoires of Target Drugs Used for Different Types of Cancer in Clinical Oncology

Inter-patient molecular heterogeneity is the major declared driver of an expanding variety of anticancer drugs and personalizing their prescriptions. Here, we compared interpatient molecular heterogeneities of tumors and repertoires of drugs or their molecular targets currently in use in clinical oncology. We estimated molecular heterogeneity using genomic (whole exome sequencing) and transcriptomic (RNA sequencing) data for 4890 tumors taken from The Cancer Genome Atlas database. For thirteen major cancer types, we compared heterogeneities at the levels of mutations and gene expression with the repertoires of targeted therapeutics and their molecular targets accepted by the current guidelines in oncology. Totally, 85 drugs were investigated, collectively covering 82 individual molecular targets. For the first time, we showed that the repertoires of molecular targets of accepted drugs did not correlate with molecular heterogeneities of different cancer types. On the other hand, we found that the clinical recommendations for the available cancer drugs were strongly congruent with the gene expression but not gene mutation patterns. We detected the best match among the drugs usage recommendations and molecular patterns for the kidney, stomach, bladder, ovarian and endometrial cancers. In contrast, brain tumors, prostate and colorectal cancers showed the lowest match. These findings provide a theoretical basis for reconsidering usage of targeted therapeutics and intensifying drug repurposing efforts.

The pervasiveness of macropinocytosis in oncological malignancies

In tumour cells, macropinocytosis functions as an amino acid supply route and supports cancer cell survival and proliferation. Initially demonstrated in oncogenic KRAS-driven models of pancreatic cancer, macropinocytosis triggers the internalization of extracellular proteins via discrete endocytic vesicles called macropinosomes. The incoming protein cargo is targeted for lysosome-dependent degradation, causing the intracellular release of amino acids. These protein-derived amino acids support metabolic fitness by contributing to the intracellular amino acid pools, as well as to the biosynthesis of central carbon metabolites. In this way, macropinocytosis represents a novel amino acid supply route that tumour cells use to survive the nutrient-poor conditions of the tumour microenvironment. Macropinocytosis has also emerged as an entry mechanism for a variety of nanomedicines, suggesting that macropinocytosis regulation in the tumour setting can be harnessed for the delivery of anti-cancer therapeutics. A slew of recent studies point to the possibility that macropinocytosis is a pervasive feature of many different tumour types. In this review, we focus on the role of this important uptake mechanism in a variety of cancers and highlight the main molecular drivers of macropinocytosis in these malignancies. This article is part of the Theo Murphy meeting issue 'Macropinocytosis'.

Potential Life-Years Lost: The Impact of the Cancer Drug Regulatory and Funding Process in Canada

BACKGROUND

Canada has an established publicly funded health care system with a complex drug approval and funding process. After proof of efficacy (POE; key publication/presentation) and before becoming publicly accessible, each drug undergoes a Health Canada approval process, a health technology assessment (HTA), a pricing negotiation, and finally individual provincial funding agreements. We quantified potential life-years lost during this process.

METHODS

We analyzed drugs for advanced lung, breast, and colorectal cancer that underwent the HTA process between 2011 and 2016. Life-years lost were calculated by multiplying documented improvement in progression-free and overall survival, number of eligible patients, and time from POE to first public funding. For conservative calculation, we assumed all eligible patients in Canada had access at the time of first public funding, whereas in reality provinces fund at different time points.

RESULTS

We analyzed 21 drugs. Of these, 15 have been funded publicly. The time from POE to first public funding ranged from 14.0 to 99.2 months (median 26.6 months). Total overall life-years lost from POE to first public funding were 39,067 (lung 32,367; breast 6,691). Progression-free life-years lost from POE to first public funding were 48,037 (lung 9,139, breast 15,827, colorectal 23,071).

CONCLUSION

The number of potential life-years lost during the drug regulatory and funding process in Canada is substantial, largely driven by delays to funding of colorectal cancer drugs. Recognizing that interprovincial differences exist and that eligible patients may not all receive a given drug, if even a fraction does so, the impact of delays remains substantive. Collaborative national initiatives are required to address this major barrier to treatment access.

IMPLICATIONS FOR PRACTICE

Patients may spend lengthy periods of time awaiting access to new and effective cancer drugs. Patients with private drug insurance or personal funds or who reside in certain Canadian provinces may obtain some drugs sooner than others, potentially creating a two-tiered access system. The cancer drug access and public funding system must be expedited to improve equity.

Phase Ib Study of Combination Therapy with MEK Inhibitor Binimetinib and Phosphatidylinositol 3-Kinase Inhibitor Buparlisib in Patients with Advanced Solid Tumors with RAS/RAF Alterations

BACKGROUND

This multicenter, open-label, phase Ib study investigated the safety and efficacy of binimetinib (MEK inhibitor) in combination with buparlisib (phosphatidylinositol 3-kinase [PI3K] inhibitor) in patients with advanced solid tumors with RAS/RAF alterations.

MATERIALS AND METHODS

Eighty-nine patients were enrolled in the study. Eligible patients had advanced solid tumors with disease progression after standard therapy and/or for which no standard therapy existed. Evaluable disease was mandatory, per RECIST version 1.1 and Eastern Cooperative Oncology Group performance status 0-2. Binimetinib and buparlisib combinations were explored in patients with KRAS-, NRAS-, or BRAF-mutant advanced solid tumors until the maximum tolerated dose and recommended phase II dose (RP2D) were defined. The expansion phase comprised patients with epidermal growth factor receptor (EGFR)-mutant, advanced non-small cell lung cancer, after progression on an EGFR inhibitor; advanced RAS- or BRAF-mutant ovarian cancer; or advanced non-small cell lung cancer with KRAS mutation.

RESULTS

At data cutoff, 32/89 patients discontinued treatment because of adverse events. RP2D for continuous dosing was buparlisib 80 mg once daily/binimetinib 45 mg twice daily. The toxicity profile of the combination resulted in a lower dose intensity than anticipated. Six (12.0%) patients with RAS/BRAF-mutant ovarian cancer achieved a partial response. Pharmacokinetics of binimetinib were not altered by buparlisib. Pharmacodynamic analyses revealed downregulation of pERK and pS6 in tumor biopsies.

CONCLUSION

Although dual inhibition of MEK and the PI3K pathways showed promising activity in RAS/BRAF ovarian cancer, continuous dosing resulted in intolerable toxicities beyond the dose-limiting toxicity monitoring period. Alternative schedules such as pulsatile dosing may be advantageous when combining therapies.

IMPLICATIONS FOR PRACTICE

Because dysregulation of the mitogen-activated protein kinase (MAPK) and the phosphatidylinositol 3-kinase (PI3K) pathways are both frequently involved in resistance to current targeted therapies, dual inhibition of both pathways may be required to overcome resistance mechanisms to single-agent tyrosine kinase inhibitors or to treat cancers with driver mutations that cannot be directly targeted. A study investigating the safety and efficacy of combination binimetinib (MEK inhibitor) and buparlisib (PI3K inhibitor) in patients harboring alterations in the RAS/RAF pathway was conducted. The results may inform the design of future combination therapy trials in patients with tumors harboring mutations in the PI3K and MAPK pathways.