Targeting KRAS in Colorectal Cancer

Clinicopathological, molecular, and prognostic features of colorectal carcinomas with KRAS c.34G>T (p.G12C) mutation

Evidence indicates that combinations of anti-EGFR antibodies and KRAS p.G12C (c.34G>T) inhibitors can be an effective treatment strategy for advanced colorectal cancer. We hypothesized that KRAS c.34G>T (p.G12C)-mutated colorectal carcinoma might be a distinct tumor subtype. We utilized a prospective cohort incident tumor biobank (including 1347 colorectal carcinomas) and detected KRAS c.34G>T (p.G12C) mutation in 43 cases (3.2%) and other KRAS mutations (in codon 12, 13, 61, or 146) in 467 cases (35%). The CpG island methylator phenotype (CIMP)-low prevalence was similarly higher in KRAS c.34G>T mutants (52%) and other KRAS mutants (49%) than in KRAS-wild-type tumors (31%). KRAS c.34G>T mutants showed higher CIMP-high prevalence (14%) and lower CIMP-negative prevalence (33%) compared with other KRAS mutants (6% and 45%, respectively; p = 0.0036). Similar to other KRAS mutants, KRAS c.34G>T-mutated tumors were associated with cecal location, non-microsatellite instability (MSI)-high status, BRAF wild type, and PIK3CA mutation when compared with KRAS-wild-type tumors. Compared with BRAF-mutated tumors, KRAS c.34G>T mutants showed more frequent LINE-1 hypomethylation, a biomarker for early-onset colorectal carcinoma. KRAS c.34G>T mutants were not associated with other features, including the tumor tissue abundance of Fusobacterium nucleatum (F. animalis), pks+ Escherichia coli, Bifidobacterium, or (enterotoxigenic) Bacteroides fragilis. Among 1122 BRAF-wild-type colorectal carcinomas, compared with KRAS-wild-type tumors, multivariable-adjusted colorectal cancer-specific mortality hazard ratios (95% confidence interval) were 1.82 (1.05-3.17) in KRAS c.34G>T (p.G12C)-mutated tumors (p = 0.035) and 1.57 (1.22-2.02) in other KRAS-mutated tumors (p = 0.0004). Our study provides novel evidence for clinical and tumor characteristics of KRAS c.34G>T (p.G12C)-mutated colorectal carcinoma.

Targeting the RAS upstream and downstream signaling pathway for cancer treatment

Cancer often involves the overactivation of RAS/RAF/MEK/ERK (MAPK) and PI3K-Akt-mTOR pathways due to mutations in genes like RAS, RAF, PTEN, and PIK3CA. Various strategies are employed to address the overactivation of these pathways, among which targeted therapy emerges as a promising approach. Directly targeting specific proteins, leads to encouraging results in cancer treatment. For instance, RTK inhibitors such as imatinib and afatinib selectively target these receptors, hindering ligand binding and reducing signaling initiation. These inhibitors have shown potent efficacy against Non-Small Cell Lung Cancer. Other inhibitors, like lonafarnib targeting Farnesyltransferase and GGTI 2418 targeting geranylgeranyl Transferase, disrupt post-translational modifications of proteins. Additionally, inhibition of proteins like SOS, SH2 domain, and Ras demonstrate promising anti-tumor activity both in vivo and in vitro. Targeting downstream components with RAF inhibitors such as vemurafenib, dabrafenib, and sorafenib, along with MEK inhibitors like trametinib and binimetinib, has shown promising outcomes in treating cancers with BRAF-V600E mutations, including myeloma, colorectal, and thyroid cancers. Furthermore, inhibitors of PI3K (e.g., apitolisib, copanlisib), AKT (e.g., ipatasertib, perifosine), and mTOR (e.g., sirolimus, temsirolimus) exhibit promising efficacy against various cancers such as Invasive Breast Cancer, Lymphoma, Neoplasms, and Hematological malignancies. This review offers an overview of small molecule inhibitors targeting specific proteins within the RAS upstream and downstream signaling pathways in cancer.

Contribution of Noncovalent Recognition and Reactivity to the Optimization of Covalent Inhibitors: A Case Study on KRasG12C

Covalent drugs might bear electrophiles to chemically modify their targets and have the potential to target previously undruggable proteins with high potency. Covalent binding of drug-size molecules includes a noncovalent recognition provided by secondary interactions and a chemical reaction leading to covalent complex formation. Optimization of their covalent mechanism of action should involve both types of interactions. Noncovalent and covalent binding steps can be characterized by an equilibrium dissociation constant (KI) and a reaction rate constant (kinact), respectively, and they are affected by both the warhead and the scaffold of the ligand. The relative contribution of these two steps was investigated on a prototypic drug target KRASG12C, an oncogenic mutant of KRAS. We used a synthetically more accessible nonchiral core derived from ARS-1620 that was equipped with four different warheads and a previously described KRAS-specific basic side chain. Combining these structural changes, we have synthesized novel covalent KRASG12C inhibitors and tested their binding and biological effect on KRASG12C by various biophysical and biochemical assays. These data allowed us to dissect the effect of scaffold and warhead on the noncovalent and covalent binding event. Our results revealed that the atropisomeric core of ARS-1620 is not indispensable for KRASG12C inhibition, the basic side chain has little effect on either binding step, and warheads affect the covalent reactivity but not the noncovalent binding. This type of analysis helps identify structural determinants of efficient covalent inhibition and may find use in the design of covalent agents.

Cross-Validation of Lipid Structure Assignment Using Orthogonal Ion Activation Modalities on the Same Mass Spectrometer

The onset and progression of cancer is associated with changes in the composition of the lipidome. Therefore, better understanding of the molecular mechanisms of these disease states requires detailed structural characterization of the individual lipids within the complex cellular milieu. Recently, changes in the unsaturation profile of membrane lipids have been observed in cancer cells and tissues, but assigning the position(s) of carbon-carbon double bonds in fatty acyl chains carried by membrane phospholipids, including the resolution of lipid regioisomers, has proven analytically challenging. Conventional tandem mass spectrometry approaches based on collision-induced dissociation of ionized glycerophospholipids do not yield spectra that are indicative of the location(s) of carbon-carbon double bonds. Ozone-induced dissociation (OzID) and ultraviolet photodissociation (UVPD) have emerged as alternative ion activation modalities wherein diagnostic product ions can enable de novo assignment of position(s) of unsaturation based on predictable fragmentation behaviors. Here, for the first time, OzID and UVPD (193 nm) mass spectra are acquired on the same mass spectrometer to evaluate the relative performance of the two modalities for lipid identification and to interrogate the respective fragmentation pathways under comparable conditions. Based on investigations of lipid standards, fragmentation rules for each technique are expanded to increase confidence in structural assignments and exclude potential false positives. Parallel application of both methods to unsaturated phosphatidylcholines extracted from isogenic colorectal cancer cell lines provides high confidence in the assignment of multiple double bond isomers in these samples and cross-validates relative changes in isomer abundance.

Human patient derived organoids: an emerging precision medicine model for gastrointestinal cancer research

Gastrointestinal cancers account for approximately one-third of the total global cancer incidence and mortality with a poor prognosis. It is one of the leading causes of cancer-related deaths worldwide. Most of these diseases lack effective treatment, occurring as a result of inappropriate models to develop safe and potent therapies. As a novel preclinical model, tumor patient-derived organoids (PDOs), can be established from patients' tumor tissue and cultured in the laboratory in 3D architectures. This 3D model can not only highly simulate and preserve key biological characteristics of the source tumor tissue in vitro but also reproduce the in vivo tumor microenvironment through co-culture. Our review provided an overview of the different in vitro models in current tumor research, the derivation of cells in PDO models, and the application of PDO model technology in gastrointestinal cancers, particularly the applications in combination with CRISPR/Cas9 gene editing technology, tumor microenvironment simulation, drug screening, drug development, and personalized medicine. It also elucidates the ethical status quo of organoid research and the current challenges encountered in clinical research, and offers a forward-looking assessment of the potential paths for clinical organoid research advancement.

The effect of novel nitrogen-based chalcone analogs on colorectal cancer cells: Insight into the molecular pathways

In colorectal cancer (CRC), aberrations in KRAS are associated with aggressive tumorigenesis and an overall low survival rate because of chemoresistance and adverse effects. Ergo, complementary, and integrative medicines are being considered for CRC treatment. Among which is the use of natural chalcones that are known to exhibit anti-tumor activities in KRAS mutant CRC subtypes treatment regimens. Consequently, we examine the effect of two novel compounds (DK13 and DK14) having chalcones with nitrogen mustard moiety on CRC cell lines (HCT-116 and LoVo) with KRAS mutation. These compounds were synthesized in our lab and previously reported to exhibit potent activity against breast cancer cells. Our data revealed that DK13 and DK14 treatment suppress cell growth, disturb the progression of cell cycle, and trigger apoptosis in CRC cell lines. Besides, treatment with both compounds impedes cell invasion and colony formation in both cell lines as compared to 5-FU; this is accompanied by up and down regulations of E-cadherin and Vimentin, respectively. At the molecular level, both compounds deregulate the expression and phosphorylation of β-catenin, Akt and mTOR, which are the main likely molecular mechanisms underlying these biological occurrences. Our findings present DK13 and DK14 as novel chemotherapies against CRC, through β-catenin/Akt/mTOR signaling pathways.

Computational insights into KRAS G12C inhibition: exploring possible repurposing of Azacitidine and Ribavirin

Kirsten rat sarcoma (KRAS) stands out as the most prevalent mutated oncogene, playing a crucial role in the initiation and progression of various cancer types, including colorectal, lung and pancreatic cancer. The oncogenic modifications of KRAS are intricately linked to tumor development and are identified in 22% of cancer patients. This has spurred the necessity to explore inhibition mechanisms, with the aim of investigating and repurposing existing drugs for diagnosing cancers dependent on KRAS G12C In this investigation, 26 nucleoside-based drugs were collected from literature to assess their effectiveness against KRAS G12C. The study incorporates in-silico molecular simulations and molecular docking examinations of these nucleoside-derived drugs with the KRAS G12C protein using Protein Data Bank (PDB) ID: 5V71. The docking outcomes indicated that two drugs, Azacitidine and Ribavirin, exhibited substantial binding affinities of -8.7 and -8.3 kcal/mol, respectively. These drugs demonstrated stability in binding to the active site of the protein during simulation studies. Root mean square deviation (RMSD) analyses indicated that the complexes closely adhered to an equilibrium RMSD value ranging from 0.17 to 0.2 nm. Additionally, % occupancies, bond angles and the length of hydrogen bonds were calculated. These findings suggest that Azacitidine and Ribavirin may potentially serve as candidates for repurposing in individuals with KRAS-dependent cancers.Communicated by Ramaswamy H. Sarma.

Differential gene expression (DGE) analysis in persons with a history of giardiasis

Giardiasis, which is caused by Giardia duodenalis, has clinical symptoms such as steatorrhea and can be very dangerous in children. In addition, some documents reported that this parasite is present inside the tissue of patients with cancer. In this study, we analyzed the gene expression profiles of some main genes important to apoptosis and anti-apoptosis in humans.Expression profile arrays of Genomic Spatial Event (GSE) 113666, GSE113667, and GSE113679 obtained from Gene Expression Omnibus were used for meta-analysis using R commands. Cytoscape and STRING databases used the protein-protein Interaction network. Then, the Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analysis was performed. Similar genes in Homo sapiens were identified using Basic Local Alignment Search Tool analysis. The validation was performed on eight people using real-time Polymerase chain reaction. In addition to the candidate genes, the gene expression of some other genes, including Serine/Threonine Kinase 1 (AKT1), Cyclin Dependent Kinase Inhibitor 2A (CDKN2A), Kirsten Rat Sarcoma (KRAS), and Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha (PIK3CA) were also examined. Analysis of the expression of serum amyloid A1 (SAA1), Regenerating Islet-Derived 3 Gamma (REG3G), and REG3A genes did not show any difference between the two groups of healthy and diseased people. Examining the mean expression of the four genes AKT1, CDKN2A, KRAS, and PIK3CA showed that three genes of AKT1, CDKN2A, and KRAS had increased expression in people with a history of giardiasis compared to healthy people. We showed that the gene expression pattern differs in apoptosis and anti-apoptosis signaling in people with a history of giardiasis. Giardia duodenalis seems to induce post-non-infectious symptoms with stimulation of human gene expression.

A perspective on emerging therapies in metastatic colorectal cancer: Focusing on molecular medicine and drug resistance

The majority of cancer cases are colorectal cancer, which is also the second largest cause of cancer-related deaths worldwide. Metastasis is the leading cause of death for patients with colorectal cancer. Metastatic colorectal cancer incidence are on the rise due to a tiny percentage of tumors developing resistant to medicines despite advances in treatment tactics. Cutting-edge targeted medications are now the go-to option for customized and all-encompassing CRC care. Specifically, multitarget kinase inhibitors, antivascular endothelial growth factors, and epidermal growth factor receptors are widely used in clinical practice for CRC-targeted treatments. Rare targets in metastatic colorectal cancer are becoming more well-known due to developments in precision diagnostics and the extensive use of second-generation sequencing technology. These targets include the KRAS mutation, the BRAF V600E mutation, the HER2 overexpression/amplification, and the MSI-H/dMMR. Incorporating certain medications into clinical trials has significantly increased patient survival rates, opening new avenues and bringing fresh viewpoints for treating metastatic colorectal cancer. These focused therapies change how cancer is treated, giving patients new hope and better results. These markers can significantly transform and individualize therapy regimens. They could open the door to precisely customized and more effective medicines, improving patient outcomes and quality of life. The fast-growing body of knowledge regarding the molecular biology of colorectal cancer and the latest developments in gene sequencing and molecular diagnostics are directly responsible for this advancement.

Current status and perspectives of genetic testing in gastrointestinal cancer (Review)

Genetic testing has become widespread in daily medical care for gastrointestinal (GI) cancers. However, unlike breast cancer and non-small cell lung cancer, in which personalized medicine targeting various driver genes is standardized, the incidence of targeted gene abnormalities in GI cancers is low. Nevertheless, such abnormalities may be linked to therapeutic agents and the further development of therapeutic agents for personalized medicine for GI cancers is desired. A liquid biopsy is of great benefit in offering clinical decision support, in applications such as GI cancer screening, surgical interventions, monitoring disease status and enhancing patient survival outcomes, all of which would contribute to personalized medicine. Germline genetic testing is required for several types of GI cancer, which shows clinical indications of hereditary predisposition. The increasing use of multigene panel testing has redefined gene-cancer associations, and consequently the estimate of cancer risk that vary from low to high penetrance. Comprehensive genetic testing can enable the detection of novel treatment targets and the discovery of undefined multiple diagnostic/predictive markers, which may enhance the molecular-level understanding of GI cancers. Genetic testing can also aid the design of more appropriate and adequate genomic-driven therapies for patients who may benefit from other standardized therapeutic methods.

Suramin, a drug for the treatment of trypanosomiasis, reduces the prothrombotic and metastatic phenotypes of colorectal cancer cells by inhibiting hepsin

Recently, our group identified serine-protease hepsin from primary tumor as a biomarker of metastasis and thrombosis in patients with localized colorectal cancer. We described hepsin promotes invasion and thrombin generation of colorectal cancer cells in vitro and in vivo and identified venetoclax as a hepsin inhibitor that suppresses these effects. Now, we aspire to identify additional hepsin inhibitors, aiming to broaden the therapeutic choices for targeted intervention in colorectal cancer.

METHODS

We developed a virtual screening based on molecular docking between the hepsin active site and 2000 compounds from DrugBank. The most promising drug was validated in a hepsin activity assay. Subsequently, we measured the hepsin inhibitor effect on colorectal cancer cells with basal or overexpression of hepsin via wound-healing, gelatin matrix invasion, and plasma thrombin generation assays. Finally, a zebrafish model determined whether hepsin inhibition reduced the invasion of colorectal cancer cells overexpressing hepsin.

RESULTS

Suramin was the most potent hepsin inhibitor (docking score: -11.9691 Kcal/mol), with an IC50 of 0.66 µM. In Caco-2 cells with basal or overexpression of hepsin, suramin decreased migration and significantly reduced invasion and thrombin generation. Suramin did not reduce the thrombotic phenotype in the hepsin-negative colorectal cancer cells HCT-116 and DLD-1. Finally, suramin significantly reduced the in vivo invasion of Caco-2 cells overexpressing hepsin.

CONCLUSION

Suramin is a novel hepsin inhibitor that reduces its protumorigenic and prothrombotic effects in colorectal cancer cells. This suggests the possibility of repurposing suramin and its derivatives to augment the repertoire of molecular targeted therapies against colorectal cancer.

Acquired resistance to KRAS G12C small-molecule inhibitors via genetic/nongenetic mechanisms in lung cancer

Inherent or acquired resistance to sotorasib poses a substantialt challenge for NSCLC treatment. Here, we demonstrate that acquired resistance to sotorasib in isogenic cells correlated with increased expression of integrin β4 (ITGB4), a component of the focal adhesion complex. Silencing ITGB4 in tolerant cells improved sotorasib sensitivity, while overexpressing ITGB4 enhanced tolerance to sotorasib by supporting AKT-mTOR bypass signaling. Chronic treatment with sotorasib induced WNT expression and activated the WNT/β-catenin signaling pathway. Thus, silencing both ITGB4 and β-catenin significantly improved sotorasib sensitivity in tolerant, acquired, and inherently resistant cells. In addition, the proteasome inhibitor carfilzomib (CFZ) exhibited synergism with sotorasib by down-regulating ITGB4 and β-catenin expression. Furthermore, adagrasib phenocopies the combination effect of sotorasib and CFZ by suppressing KRAS activity and inhibiting cell cycle progression in inherently resistant cells. Overall, our findings unveil previously unrecognized nongenetic mechanisms underlying resistance to sotorasib and propose a promising treatment strategy to overcome resistance.

A Review of Translational Research for Targeted Therapy for Metastatic Colorectal Cancer

Colorectal cancer is the third most common cause of cancer-related death in the United States, with 20% of patients presenting with metastatic disease at the time of diagnosis. Metastatic colon cancer is often treated with a combination of surgery, systemic therapy (chemotherapy, biologic therapy, immunotherapy), and/or regional therapy (hepatic artery infusion pumps). Utilizing the molecular and pathologic features of the primary tumor to tailor treatment for patients may improve overall survival. Rather than a "one size fits all" approach, a more nuanced treatment plan guided by the unique features of a patient's tumor and the tumor's microenvironment can more effectively treat the disease. Basic science work to elucidate new drug targets, understand mechanisms of evasion, and develop drugs and drug combinations is critical to inform clinical trials and identify novel, effective therapies for metastatic colorectal cancer. Through the lens of key targets for metastatic colorectal cancer, this review discusses how work in the basic science lab translates into clinical trials.

Design, synthesis and biological evaluation of KRASG12C-PROTACs

Several small-molecule covalent inhibitors of KRAS^G12C have made breakthrough progress in the treatment of KRAS mutant cancer. However, the clinical application of KRAS^G12C small-molecule inhibitors may be limited by adaptive resistance. Emerging PROTAC strategy can achieve complementary advantages with small molecule inhibitors and improve anti-tumor efficacy. Based on AMG-510, a series of novel KRAS^G12C-PROTACs were designed and synthesized. The protein degradation assay showed that PROTACs I-1, II-1, III-2 and IV-1 had binding and degradation ability to KRAS^G12C. III-2 and IV-1 showed potent inhibitory effect on downstream p-ERK and were more potent than AMG-510. Mechanistic studies demonstrated that PROTACs exerted degradation effects through the ubiquitin-proteasome pathway. Using cell lines sensitive to KRAS^G12C, anti-proliferative activities of compounds were assessed. PROTACs tested showed overall anti-proliferative activities. Besides,the structure-activity relationships (SARs) of KRAS^G12C-PROTACs were summarized. These results supported the use of the PROTAC strategy to degrade oncogene KRAS^G12C and provided clues for structural optimization of KRAS^G12C-PROTACs.

IL1RN and PRRX1 as a Prognostic Biomarker Correlated with Immune Infiltrates in Colorectal Cancer: Evidence from Bioinformatic Analysis

The extensive morbidity of colorectal cancer (CRC) and the inferior prognosis of terminal CRC urgently call for reliable prognostic biomarkers. For this, we identified 704 differentially expressed genes (DEGs) by intersecting three datasets, GSE41328, GSE37364, and GSE15960 from Gene Expression Omnibus database, to maximize the accuracy of the results. Preliminary analysis of the DEGs was then performed using online gene analysis datasets, such as DAVID, UCSC Cancer Genome Browser, CBioPortal, STRING, and UCSC Cancer Genome Browser. Cytoscape was utilized to visualize the protein perception interaction network of DEGs, and the bubble map of GO and KEGG enrichment function was demonstrated using the R package. The Molecular Complex Detection (MCODE), Biological Network Gene Oncology (BiNGO) plug-in in Cytoscape, was applied to further screen the DEGs to obtain 15 seed genes, which were IL1RN, GALNT12, ADH6, SCN7A, CXCL1, FGF18, SOX9, ACACB, PRRX1, MZB1, SLC22A3, CNNM4, LY6E, IFITM2, and GDPD3. Among them, IL1RN, ADH6, SCN7A, ACACB, MZB1, and GDPD3 exhibited statistically significant survival differences, whereas limited studies were conducted in CRC. Based on the enrichment results of the "Gene Ontology"(GO) and "Kyoto Encyclopedia of Genes and genomes "(KEGG) as well as documented findings of key genes, we further emphasized the potential of IL1RN and PRRX1 as markers of immune infiltrates in CRC and confirmed our hypothesis by compiling data from the UALCAN, Tumor Immune Estimation Resource, and TISIDB databases for these two genes. The above-mentioned genes might offer a valuable insight into the diagnosis, immunotherapeutic targets, and prognosis of CRC.

Adagrasib, a KRAS G12C inhibitor, reverses the multidrug resistance mediated by ABCB1 in vitro and in vivo

Background

Multidrug resistance (MDR) is a complex phenomenon that frequently leads to chemotherapy failure during cancer treatment. The overexpression of ATP-binding cassette (ABC) transporters represents the major mechanism contributing to MDR. To date, no effective MDR modulator has been applied in clinic. Adagrasib (MRTX849), a specific inhibitor targeting KRAS G12C mutant, is currently under investigation in clinical trials for the treatment of non-small cell lung cancer (NSCLC). This study focused on investigating the circumvention of MDR by MRTX849.

Methods

The cytotoxicity and MDR reversal effect of MRTX849 were assessed by MTT assay. Drug accumulation and drug efflux were evaluated by flow cytometry. The MDR reversal by MRTX849 in vivo was investigated in two ABCB1-overexpressing tumor xenograft models in nude mice. The interaction between MRTX849 and ABCB1 substrate binding sites was studied by the [125I]-IAAP-photoaffinity labeling assay. The vanadate-sensitive ATPase assay was performed to identify whether MRTX849 would change ABCB1 ATPase activity. The effect of MRTX849 on expression of ABCB1 and PI3K/AKT signaling molecules was examined by flow cytometry, Western blot and Quantitative Real-time PCR analyses.

Results

MRTX849 was shown to enhance the anticancer efficacy of ABCB1 substrate drugs in the transporter-overexpressing cells both in vitro and in vivo. The MDR reversal effect was specific against ABCB1 because no similar effect was observed in the parental sensitive cells or in ABCG2-mediated MDR cells. Mechanistically, MRTX849 increased the cellular accumulation of ABCB1 substrates including doxorubicin (Dox) and rhodamine 123 (Rho123) in ABCB1-overexpressing MDR cells by suppressing ABCB1 efflux activity. Additionally, MRTX849 stimulated ABCB1 ATPase activity and competed with [125I]-IAAP for photolabeling of ABCB1 in a concentration-dependent manner. However, MRTX849 did not alter ABCB1 expression or phosphorylation of AKT/ERK at the effective MDR reversal drug concentrations.

Conclusions

In summary, MRTX849 was found to overcome ABCB1-mediated MDR both in vitro and in vivo by specifically attenuating ABCB1 efflux activity in drug-resistant cancer cells. Further studies are warranted to translate the combination of MRTX849 and conventional chemotherapy to clinical application for circumvention of MDR.

Molecular Biology and Therapeutic Perspectives for K-Ras Mutant Non-Small Cell Lung Cancers

In non-small cell lung cancer (NSCLC) the most common alterations are identified in the Kirsten rat sarcoma viral oncogene homolog (KRAS) gene, accounting for approximately 30% of cases in Caucasian patients. The majority of mutations are located in exon 2, with the c.34G > T (p.G12C) change being the most prevalent. The clinical relevance of KRAS mutations in NSCLC was not recognized until a few years ago. What is now emerging is a dual key role played by KRAS mutations in the management of NSCLC patients. First, recent data report that KRAS-mutant lung AC patients generally have poorer overall survival (OS). Second, a KRAS inhibitor specifically targeting the c.34G > T (p.G12C) variant, Sotorasib, has been approved by the U.S. Food and Drug Administration (FDA) and by the European Medicines Agency. Another KRAS inhibitor targeting c.34G > T (p.G12C), Adagrasib, is currently being reviewed by the FDA for accelerated approval. From the description of the biology of KRAS-mutant NSCLC, the present review will focus on the clinical aspects of KRAS mutations in NSCLC, in particular on the emerging efficacy data of Sotorasib and other KRAS inhibitors, including mechanisms of resistance. Finally, the interaction between KRAS mutations and immune checkpoint inhibitors will be discussed.

Prognostic Value of KRAS Mutations in Colorectal Cancer Patients

Simple Summary

Kirsten rat sarcoma viral oncogene homolog (KRAS)-mutated colorectal cancer (CRC) seems to have a different biological behavior and therapeutic approach compared with non-KRAS mutated CRC. Except for the proven predictive significance of KRAS mutations in CRC patients, their prognostic significance is still under evaluation. Our study shows that 93.2% of RAS-mutated patients were KRAS mutants, with G12D being the most common subtype. KRAS G12D mutation is correlated with better overall survival (OS). KRAS G12C mutations may indicate worse prognosis regarding progression free (PFS) and OS, as well as exon 4 and exon 3 KRAS mutations for PFS and OS, respectively. Further studies are warranted to confirm these results.

Abstract

Colorectal cancer (CRC) remains a major public health issue. The detection of parameters that affect CRC prognosis is of great significance. KRAS mutations, play a crucial role in tumorigenesis with a strong predictive value. KRAS-mutated stage-IV CRC patients gain no benefit of the anti-EGFR therapy. The KRAS G12C mutation subtype is under investigation for treatment regimens. The present study aimed to detect various RAS mutations in a cohort of 578 RAS-mutated CRC patients; 49% of them had de novo metastatic disease; 60% were male; 71.4% had left-sided tumors; and 94.6% had a good performance status. KRAS mutations were detected in 93.2% of patients, with KRAS G12D being the most common subtype (30.1%). KRAS mutations presented shorter progression-free (PFS) and overall survival (OS), compared with NRAS mutations, although not significantly (PFS: 13.8 vs. 18.5 months; p = 0.552; OS: 53.1 vs. 60.9 months; p = 0.249). KRAS G12D mutations presented better OS rates (p = 0.04). KRAS G12C mutation, even though not significantly, presented worse PFS and OS rates. KRAS exon 3 and 4 mutations presented different PFS and OS rates, although these were not significant. Concluding, KRAS G12D and G12C mutations lead to better and worst prognosis, respectively. Further studies are warranted to validate such findings and their possible therapeutic implication.

Colorectal cancer-derived exosomes and modulation KRAS signaling

Colorectal cancer (CRC) is one of the most common cancers worldwide and one of the main causes of cancer-associated mortality. At the period of diagnosis, metastases to other tissues will be present in around 30% of CRC individuals. Individuals with CRC continue to have a poor prognosis despite advances in medication. There is a growing body of literature that CRC develops as a result of the aggregation of various mutations in tumor oncogenes or suppressor genes and that diagnosing cancer in its initial phases may assist in increasing the overall lifespan of individuals with the illness. On the other hand, tumor cells may discharge exosomes in response to oncogenic mutations. By Inhibiting signaling pathways, including the Kirsten rat sarcoma virus (KRAS) mechanism, which is important in a variety of cell activities, exosomes have been shown to cause colorectal cancer in animal studies. The purpose of this review was to summarize the latest discoveries on the modulation of KRAS signaling by exosomes extracted from colorectal cancer.

Biglycan as a potential regulator of tumorgenicity and immunogenicity in K-RAS-transformed cells

The extracellular matrix component biglycan (BGN) plays an essential role in various physiological and pathophysiological processes. A deficient BGN expression associated with reduced immunogenicity was found in HER-2/neu-overexpressing cells. To determine whether BGN is suppressed by oncogene-driven regulatory networks, the expression and function of BGN was analyzed in murine and human BGNlow/BGNhigh K-RASG12V-transformed model systems as well as in different patients' datasets of colorectal carcinoma (CRC) lesions. K-RAS-mutated CRC tissues expressed low BGN mRNA and protein levels when compared to normal colon epithelial cells, which was associated with a reduced patients' survival. Transfection of BGN in murine and human BGNlow K-RAS-expressing cells resulted in a reduced growth and migration of BGNhigh vs BGNlow K-RAS cells. In addition, increased MHC class I surface antigens as a consequence of an enhanced antigen processing machinery component expression was found upon restoration of BGN, which was confirmed by RNA-sequencing of BGNlow vs. BGNhigh K-RAS models. Furthermore, a reduced tumor formation of BGNhigh versus BGNlow K-RAS-transformed fibroblasts associated with an enhanced MHC class I expression and an increased frequency of tumor-infiltrating lymphocytes in tumor lesions was found. Our data provide for the first time an inverse link between BGN and K-RAS expression in murine and human K-RAS-overexpressing models and CRC lesions associated with altered growth properties, reduced immunogenicity and worse patients' outcome. Therefore, reversion of BGN might be a novel therapeutic option for K-RAS-associated malignancies.

Clinical Utility of Genomic Profiling Tests in Patients with Advanced Gastrointestinal Cancers

BACKGROUND

Comprehensive analyses of cancer-related genomic alterations are expected to lead to increased availability of targeted therapies. However, in patients with gastrointestinal (GI) cancers, the utility of genomic profiling is unclear because of common non-druggable alterations and rapid disease progression that prevent a sufficient time period to seek targets.

OBJECTIVE

The aim of this study was to determine the utility of genomic profiling tests in patients with GI cancers.

METHODS

The subjects of this retrospective study were patients with GI cancers and patients with non-GI cancers who underwent tissue-based genomic profiling at a single institution from April 2017 to October 2020. The profile of gene alterations, frequency of tumor mutational burden-high (≥ 10 Muts/Mb), and accessibility of recommended molecular targeted therapy were compared between patients with GI cancers and patients with non-GI cancers.

RESULTS

In all, 133 patients with GI cancers and 63 patients with non-GI cancers were included. The genomic profiles of GI cancers showed the highest frequencies of TP53, KRAS, and APC mutations and a significantly lower frequency of PIK3CA mutations than those of non-GI cancers. Tumor mutational burden-high was significantly less prevalent in GI cancers (4% vs 20%, p = 0.008). Twenty-nine patients with GI cancers (40%) and 35 patients with non-GI cancers (56%) were recommended for targeted therapies based on the findings. Among them, seven patients each with GI cancers and non-GI cancers received the recommended therapy on their genomic findings, which showed similar treatment accessibility between the GI and non-GI cancer groups (10% vs 11%, p = 0.791). HER2-targeted and BRAF-targeted therapies were the primary treatments administered to patients with GI cancers.

CONCLUSIONS

Although their genomic profiles revealed fewer druggable sites, patients with GI cancers accessed targeted therapies similarly to patients with non-GI cancers. The utility of genomic profile testing in patients with GI cancers was highlighted to determine if patients can receive specific treatments, such as HER2-targeted and BRAF-targeted therapies.

KRAS-G12C Mutation in One Real-Life and Three Population-Based Nordic Cohorts of Metastatic Colorectal Cancer

Background

KRAS mutations, present in over 40% of metastatic colorectal cancer (mCRC), are negative predictive factors for anti-EGFR therapy. Mutations in KRAS-G12C have a cysteine residue for which drugs have been developed. Published data on this specific mutation are conflicting; thus, we studied the frequency and clinical characteristics in a real-world and population-based setting.

Methods

Patients from three Nordic population-based cohorts and the real-life RAXO-study were combined. RAS and BRAF tests were performed in routine healthcare, except for one cohort. The dataset consisted of 2,559 patients, of which 1,871 could be accurately classified as KRAS, NRAS, and BRAF-V600E. Demographics, treatments, and outcomes were compared using logistic regression. Overall survival (OS) was estimated with Kaplan–Meier, and differences were compared using Cox regression, adjusted for baseline factors.

Results

The KRAS-G12C frequency was 2%–4% of all tested in the seven cohorts (mean 3%) and 4%–8% of KRAS mutated tumors in the cohorts (mean 7%). Metastasectomies and ablations were performed more often (38% vs. 28%, p = 0.040), and bevacizumab was added more often (any line 74% vs. 59%, p = 0.007) for patients with KRAS-G12C- vs. other KRAS-mutated tumors, whereas chemotherapy was given to similar proportions. OS did not differ according to KRAS mutation, neither overall (adjusted hazard ratio (HR) 1.03; 95% CI 0.74–1.42, reference KRAS-G12C) nor within treatment groups defined as “systemic chemotherapy, alone or with biologics”, “metastasectomy and/or ablations”, or “best supportive care”, RAS and BRAF wild-type tumors (n = 548) differed similarly to KRAS-G12C, as to other KRAS- or NRAS-mutated (n = 66) tumors.

Conclusions

In these real-life and population-based cohorts, there were no significant differences in patient characteristics and outcomes between patients with KRAS-G12C tumors and those with other KRAS mutations. This contrasts with the results of most previous studies claiming differences in many aspects, often with worse outcomes for those with a KRAS-G12C mutation, although not consistent. When specific drugs are developed, as for this mutation, differences in outcome will hopefully emerge.

Association Between Tumor Mutation Profile and Clinical Outcomes Among Hispanic-Latino Patients With Metastatic Colorectal Cancer

In the United States, CRC is the third most common type of cancer and the second leading cause of cancer-related death. Although the incidence of CRC among the Hispanic population has been declining, recently, a dramatic increase in CRC incidents among HL younger than 50 years of age has been reported. The incidence of early-onset CRC is more significant in HL population (45%) than in non-Hispanic Whites (27%) and African-Americans (15%). The reason for these racial disparities and the biology of CRC in the HL are not well understood. We performed this study to understand the biology of the disease in HL patients. We analyzed formalin-fixed paraffin-embedded tumor tissue samples from 52 HL patients with mCRC. We compared the results with individual patient clinical histories and outcomes. We identified commonly altered genes in HL patients (APC, TP53, KRAS, GNAS, and NOTCH). Importantly, mutation frequencies in the APC gene were significantly higher among HL patients. The combination of mutations in the APC, NOTCH, and KRAS genes in the same tumors was associated with a higher risk of progression after first-line of chemotherapy and overall survival. Our data support the notion that the molecular drivers of CRC might be different in HL patients.

Development and Validation of a Targeted ‘Liquid’ NGS Panel for Treatment Customization in Patients with Metastatic Colorectal Cancer

The detection of actionable mutations in tumor tissue is a prerequisite for treatment customization in patients with metastatic colorectal cancer (mCRC). Analysis of circulating tumor DNA (ctDNA) for the identification of such mutations in patients’ plasma is an attractive alternative to invasive tissue biopsies. Despite having the high analytical sensitivity required for ctDNA analysis, digital polymerase chain reaction (dPCR) technologies can only detect a very limited number of hotspot mutations, whilst a broader mutation panel is currently needed for clinical decision making. Recent advances in next-generation sequencing (NGS) have led to high-sensitivity platforms that allow screening of multiple genes at a single assay. Our goal was to develop a small, cost- and time-effective NGS gene panel that could be easily integrated in the day-to-day clinical routine in the management of patients with mCRC. We designed a targeted panel comprising hotspots in six clinically relevant genes (KRAS, NRAS, MET, BRAF, ERBB2 and EGFR) and validated it in a total of 68 samples from 30 patients at diagnosis, first and second disease progression. Results from our NGS panel were compared against plasma testing with BEAMing dPCR regarding the RAS gene status. The overall percent of agreement was 83.6%, with a positive and negative percent agreement of 74.3% and 96.2%, respectively. Further comparison of plasma NGS with standard tissue testing used in the clinic showed an overall percent agreement of 86.7% for RAS status, with a positive and negative percent agreement of 81.2% and 92.8%, respectively. Thus, our study strongly supports the validity and efficiency of an affordable targeted NGS panel for the detection of clinically relevant mutations in patients with mCRC.