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Kirsten rat sarcoma viral oncogene homologue (KRAS) is one of the most highly mutated oncogenes in human cancer, occurring in 95% of pancreatic, 50% of colorectal, and 32% of lung adenocarcinomas a...

Kirsten rat sarcoma viral oncogene homolog (KRAS) is one of the most common mutant oncogenes in non‐small cell lung cancer (NSCLC). The survival of patients with KRAS mutations may be much lower than patients without KRAS mutations. However, due to the complex structure and diverse biological properties, it is difficult to achieve specific inhibitors for the direct elimination of KRAS activity, making KRAS a challenging therapeutic target. At present, with the tireless efforts of medical research, including KRAS G12C inhibitors, immunotherapy and other combination strategies, this dilemma is expected to an end. In addition, inhibition of the downstream signaling pathways of KRAS may be a promising combination strategy. Given the rapid development of treatments, understanding the details will be important to determine the individualized treatment options, including combination therapy and potential resistance mechanisms., The survival of patients with KRAS mutations may be much lower than patients without KRAS mutations. At present, with the tireless efforts of medical research, including KRAS G12C inhibitors, immunotherapy and other combination strategy, this dilemma of KRAS mutated NSCLC is expected to an end.

In close to equilibrium conditions (1° per 400 min), the DSC measurements demonstrated that the melting parameters of white rat sarcoma M1 procollagen equaled to Tm = 34.4 °C and ΔTm = 2.7°, and the same parameters of fibers reconstructed from those solutions of procollagen were Tm = 38.5 °C and ΔT = 3.1°. These values were by 1.0° lower and 0.8° wider, and by 1.7° lower and 0.7° wider in comparison with the parameters of procollagen and fibers of healthy rat tissue, accordingly. The simultaneous increase in melting temperature and melting width, and a weak decrease in melting enthalpy demonstrated that sarcoma M1 procollagen had some defects. The considerable decrease by 7° in melting temperature and decrease in thermostability of procollagen fibrils in case of sarcoma M1 in comparison to the healthy norm gives a good prospective potential of using this approach as a quick DSC test to detect various sarcomas, including human sarcomas, by comparing the biopsy material or postsurgical tissues with the normal samples.

Oncogenic Kirsten RAt Sarcoma (KRAS) mutations are attractive targets in non-small-cell lung cancer (NSCLC). Thus, the objective of this work is to discover promising inhibitors that target this protein using

Kirsten rat sarcoma viral oncogene (K-ras) is one of the most frequent mutations of non-small cell lung cancer (NSCLC), specifically lung adenocarcinoma. Historically K-ras has been a mutation of great resilience and complexity. This shifted the focus of therapies to several of its related signaling pathways and cytokines. However, due to a greater understanding of the intricacies behind this mutation a greater arsenal of therapies has become available to us in the form of direct K-ras therapy. With this cumulative knowledge, we hope to bring an end to this irrepressible mutation in the future.

Colorectal cancer (CRC) is a heterogeneous disease at the cellular and molecular levels. Kirsten rat sarcoma (KRAS) is a commonly mutated oncogene in CRC, with mutations in approximately 40% of all CRC cases; its mutations result in constitutive activation of the KRAS protein, which acts as a molecular switch to persistently stimulate downstream signaling pathways, including cell proliferation and survival, thereby leading to tumorigenesis. Patients whose CRC harbors KRAS mutations have a dismal prognosis. Currently, KRAS mutation testing is a routine clinical practice before treating metastatic cases, and the approaches developed to detect KRAS mutations have exhibited favorable sensitivity and accuracy. Due to the presence of KRAS mutations, this group of CRC patients requires more precise therapies. However, KRAS was historically thought to be an undruggable target until the development of KRASG12C allele-specific inhibitors. These promising inhibitors may provide novel strategies to treat KRAS-mutant CRC. Here, we provide an overview of the role of KRAS in the prognosis, diagnosis and treatment of CRC.

PURPOSE OF REVIEW The unique structure made Kirsten rat sarcoma (KRAS) 'undruggable' for quite an extended period. The functional mechanism of this small protein is well illustrated. However, there is no precision medicine for nonsmall cell lung cancer (NSCLC) patients burden with KRAS mutation. The attempts made by scientists to make challenge history against KRAS mutation and their druggable targets are worth elucidating. RECENT FINDINGS The appearance of orphan drug AMG510 in the market specifically targeting KRASG12C is a tremendous breakthrough. Several KRAS inhibitors are under development now. More studies focus on combo treatment of KRAS inhibition and immune checkpoint inhibitors (ICIs). Recent preclinical and clinical investigations have been reported that NSCLC patients with KRAS mutation can benefit from ICIs. SUMMARY The current review elucidates the development of KRAS inhibitors from basic research to clinical precision medicines. We retrospectively analyze the development of KRAS mutation targeting drugs and discuss the investigations for future development of KRAS inhibitors.

The lipid-anchored RAS (Rat sarcoma) small GTPases (guanosine triphosphate hydrolases) are highly prevalent in human cancer. Traditional strategies of targeting the enzymatic activities of RAS have been shown to be difficult. Alternatively, RAS function and pathology are mostly restricted to nanoclusters on the plasma membrane (PM). Lipids are important structural components of these signaling platforms on the PM. However, how RAS nanoclusters selectively enrich distinct lipids in the PM, how different lipids contribute to RAS signaling and oncogenesis and whether the selective lipid sorting of RAS nanoclusters can be targeted have not been well-understood. Latest advances in quantitative super-resolution imaging and molecular dynamic simulations have allowed detailed characterization RAS/lipid interactions. In this review, we discuss the latest findings on the select lipid composition (with headgroup and acyl chain specificities) within RAS nanoclusters, the specific mechanisms for the select lipid sorting of RAS nanoclusters on the PM and how perturbing lipid compositions within RAS nanoclusters impacts RAS function and pathology. We also describe different strategies of manipulating lipid composition within RAS nanoclusters on the PM.

Early identification of epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations is crucial for selecting a therapeutic strategy for patients with non-small-cell lung cancer (NSCLC). We proposed a machine learning-based model for feature selection and prediction of EGFR and KRAS mutations in patients with NSCLC by including the least number of the most semantic radiomics features. We included a cohort of 161 patients from 211 patients with NSCLC from The Cancer Imaging Archive (TCIA) and analyzed 161 low-dose computed tomography (LDCT) images for detecting EGFR and KRAS mutations. A total of 851 radiomics features, which were classified into 9 categories, were obtained through manual segmentation and radiomics feature extraction from LDCT. We evaluated our models using a validation set consisting of 18 patients derived from the same TCIA dataset. The results showed that the genetic algorithm plus XGBoost classifier exhibited the most favorable performance, with an accuracy of 0.836 and 0.86 for detecting EGFR and KRAS mutations, respectively. We demonstrated that a noninvasive machine learning-based model including the least number of the most semantic radiomics signatures could robustly predict EGFR and KRAS mutations in patients with NSCLC.

Kirsten Rat Sarcoma (KRAS) is a master oncogene involved in cellular proliferation and survival and is the most commonly mutated oncogene in all cancers. Activating KRAS mutations are present in over 90% of pancreatic ductal adenocarcinoma (PDAC) cases and are implicated in tumor initiation and progression. Although KRAS is a critical oncogene, and therefore an important therapeutic target, its therapeutic inhibition has been very challenging, and only recently specific mutant KRAS inhibitors have been discovered. In this review, we discuss the activation of KRAS signaling and the role of mutant KRAS in PDAC development. KRAS has long been considered undruggable, and many drug discovery efforts which focused on indirect targeting have been unsuccessful. We discuss the various efforts for therapeutic targeting of KRAS. Further, we explore the reasons behind these obstacles, novel successful approaches to target mutant KRAS including G12C mutation as well as the mechanisms of resistance.

To examine the prognostic impact of tumor laterality in colon cancer liver metastases (CLM) after stratifying by Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) mutational status.Although some studies have demonstrated that patients with CLM from a right sided (RS) primary cancer fare worse, others have found equivocal outcomes of patients with CLM with RS versus left-sided (LS) primary tumors. Importantly, recent evidence from unresectable metastatic CRC suggests that tumor laterality impacts prognosis only in those with wild-type tumors.Patients with rectal or transverse colon tumors and those with unknown KRAS mutational status were excluded from analysis. The prognostic impact of RS versus LS primary CRC was determined after stratifying by KRAS mutational status.277 patients had a RS (38.6%) and 441 (61.4%) had a LS tumor. Approximately one-third of tumors (28.1%) harbored KRAS mutations. In the entire cohort, RS was associated with worse 5-year overall survival (OS) compared with LS (39.4% vs 50.8%, P = 0.03) and remained significantly associated with worse OS in the multivariable analysis (hazard ratio 1.45, P = 0.04). In wild-type patients, a worse 5-year OS associated with a RS tumor was evident in univariable analysis (43.7% vs 55.5%, P = 0.02) and persisted in multivariable analysis (hazard ratio 1.49, P = 0.01). In contrast, among patients with KRAS mutated tumors, tumor laterality had no impact on 5-year OS, even in the univariable analysis (32.8% vs 34.0%, P = 0.38).This study demonstrated, for the first time, that the prognostic impact of primary tumor side differs according to KRAS mutational status. RS tumors were associated with worse survival only in patients with wild-type tumors.

Background/aim Spontaneous regression (SR) of tumours is a rare phenomenon not yet fully understood. The aim of this study was to investigate immune cells infiltrating progressive and SR tumours in a Lewis rat sarcoma model. Materials and methods Rats were subcutaneously inoculated with rat sarcoma R5-28 (clone C4) cells. Developing tumours were obtained on day 42 and cryosections were immunohistochemically processed for detection of immune cells. Results A high density of granulocytes was found in the necrotic areas of both progressive and SR tumours. CD4+ cells and CD8+ cells were rare and sparsely dispersed in the tumour tissue without clear difference between the two types of tumours. On the contrary, CD161+ cells were abundant and evenly distributed in SR tumours, but these cells were very rare in progressive tumours. Conclusion Based on the differences in number and distribution of the immune cell subpopulations, we believe that natural killer (CD161+) cells play a major role in the destruction of cancer cells during SR of tumours in this Lewis rat model.

Simple Summary A better understanding of the role of KRAS and its different mutations has led to the development of specific small-molecule inhibitors able to target KRAS G12C, an oncogenic driver mutation in a number of cancers, including non-small cell lung cancer. While these therapies hold great promise, they face the same limitation as other kinase inhibitors, the emergence of resistant mechanisms. The biology behind KRAS G12C inhibitor resistance has been investigated with genome-wide approaches, in the hopes of finding a way to improve the efficacy of these new molecules. Here, we review the biology of KRAS G12C, mechanisms of drug resistance and potential approaches to overcome the later. Abstract Lung cancer represents the most common form of cancer, accounting for 1.8 million deaths globally in 2020. Over the last decade the treatment for advanced and metastatic non-small cell lung cancer have dramatically improved largely thanks to the emergence of two therapeutic breakthroughs: the discovery of immune checkpoint inhibitors and targeting of oncogenic driver alterations. While these therapies hold great promise, they face the same limitation as other inhibitors: the emergence of resistant mechanisms. One such alteration in non-small cell lung cancer is the Kirsten Rat Sarcoma (KRAS) oncogene. KRAS mutations are the most common oncogenic driver in NSCLC, representing roughly 20–25% of cases. The mutation is almost exclusively detected in adenocarcinoma and is found among smokers 90% of the time. Along with the development of new drugs that have been showing promising activity, resistance mechanisms have begun to be clarified. The aim of this review is to unwrap the biology of KRAS in NSCLC with a specific focus on primary and secondary resistance mechanisms and their possible clinical implications.

Oncogenic RAS (Rat sarcoma) mutations drive more than half of human cancers, and RAS inhibition is the holy grail of oncology. Thirty years of relentless efforts and harsh disappointments have taught us about the intricacies of oncogenic RAS signalling that allow us to now get a pharmacological grip on this elusive protein. The inhibition of effector pathways, such as the RAF-MEK-ERK pathway, has largely proven disappointing. Thus far, most of these efforts were aimed at blocking the activation of ERK. Here, we discuss RAF-dependent pathways that are regulated through RAF functions independent of catalytic activity and their potential role as targets to block oncogenic RAS signalling. We focus on the now well documented roles of RAF kinase-independent functions in apoptosis, cell cycle progression and cell migration.

Simple Summary Metastatic colorectal cancer (mCRC) represents a significant burden in cancer-related morbidity and mortality. The study of mCRC-related genetic alterations and the molecular landscape of the disease has been ongoing and continues to improve the efficacy of the available treatment options. Here, we review various molecular pathways that are involved in colorectal carcinogenesis with driving mutations that could be targeted for precision approaches in the treatment of mCRC. We summarize groundbreaking clinical trials that are shaping the evolving role of precision approaches in the practice guidelines and discuss the latest advancements in emerging new modalities, novel technologies, and future directions toward individualizing the managemet approaches to the treatment of colorectal cancer. Abstract The genetic and molecular underpinnings of metastatic colorectal cancer have been studied for decades, and the applicability of these findings in clinical decision making continues to evolve. Advancements in translating molecular studies have provided a basis for tailoring chemotherapeutic regimens in metastatic colorectal cancer (mCRC) treatment, which have informed multiple practice guidelines. Various genetic and molecular pathways have been identified as clinically significant in the pathogenesis of metastatic colorectal cancer. These include rat sarcoma (RAS), epithelial growth factor receptor (EGFR), vascular endothelial growth factor VEGF, microsatellite instability, mismatch repair, and v-raf murine sarcoma viral oncogene homolog b1 (BRAF) with established clinical implications. RAS mutations and deficiencies in the mismatch repair pathway guide decisions regarding the administration of anti-EGFR-based therapies and immunotherapy, respectively. Furthermore, there are several emerging pathways and therapeutic modalities that have not entered mainstream use in mCRC treatment and are ripe for further investigation. The well-established data in the arena of targeted therapies provide evidence-based support for the use or avoidance of various therapeutic regimens in mCRC treatment, while the emerging pathways and platforms offer a glimpse into the future of transforming a precision approach into a personalized treatment.

Colorectal cancer (CRC) is the third most common cancer in the world and is the second leading cause of cancer-related deaths. Several mutations are involved in the development of CRC. The prognostic significance of the KRAS mutation has been discussed in many studies. We aimed to investigate the prognostic significance of the number of KRAS mutations in metastatic CRC (mCRC). Patients with mutations in the KRAS gene were included in the study. They were divided into 2 groups as single mutation and multiple mutations in the KRAS gene. For the study, 425 CRC patients were screened. KRAS mutation was positive in 191 patients (45%). One hundred ninety-one patients were included in the study, 171 patients (90%) had single mutations and 20 patients (10%) had multiple mutations. Median progression-free survival was 12.8 months in patients with multiple mutations, while it was 8.8 months in patients with single mutations (P: .05). The median overall survival of patients with multiple mutations was 40.7 months, while it was 22.7 months for patients with single mutations (P = .01) We found that the presence of multiple mutations in KRAS mutant patients was associated with better overall survival and progression-free survival than a single mutation.

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest solid tumors in the world. Currently, there are no approved targeted therapies for PDAC. Mutations in Kirsten rat sarcoma viral oncogene homologue (KRAS) are known to be a major driver of PDAC progression, but it was considered an undruggable target until recently. Moreover, PDAC also suffers from drug delivery issues due to the highly fibrotic tumor microenvironment. In this perspective, we provide an overview of recent developments in targeting mutant KRAS and strategies to overcome drug delivery issues (e.g., nanoparticle delivery). Overall, we propose that the antitumor effects from novel KRAS inhibitors along with strategies to overcome drug delivery issues could be a new therapeutic way forward in PDAC.

In the modern era of biomarker-driven precision oncology, it is no surprise that the Kirsten rat sarcoma (KRAS) oncogene is topping the current list of our ‘most-wanted’ targets. Developing an effe...

Despite the high prevalence of Kirsten rat sarcoma (KRAS) mutations in non-small cell lung cancer (NSCLC), for a long time it has been defined as an 'undruggable target', with precision medicine not considered as an adequate approach to treat this subgroup of patients. After several years of efforts, preliminary data from early clinical trials have recently demonstrated that direct pharmacological inhibition of KRAS p.G12C mutation is possible, emerging as an effective targeted treatment for about 10-12% of patients with advanced NSCLC, with potential relevant impact on their long-term survival and quality of life. This review reports the current status of KRAS mutations detection in the Italian real-word scenario, summarises the biological basis of KRAS inhibition in NSCLC and provides an updated overview of therapeutic strategies, discussing the potential reasons for past failures and analysing the upcoming challenges related to the advent of new targeted agents in clinical practice.

To analyze the expression of micro-RNA 143 (miRNA-143) in the patients with pancreatic cancer and to explore the influence of overexpression of miRNA-143 on pancreatic cancer cells.Twenty-five patients with pancreatic cancer that received treatment in their hospital were included in this study. Pancreatic cancer tissues of the patients were surgically removed, and cancer-adjacent tissues were taken for control. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expressions of miRNA-143 and its target gene Kirsten rat sarcoma (KRAS) in pancreatic cancer tissues and cancer-adjacent tissues. Western blot test was conducted to detect the expression of KRAS in pancreatic cancer tissues. Clinicopathologic data of patients were recorded in detail, and the analysis on the correlation of these data with the expression of miRNA-143 in pancreatic cancer tissues was conducted. Pancreatic cancer cell line (PANC-1) was transfected with plasmid for overexpression of miRNA-143, and the influences of miRNA-143 on the apoptosis, migration ability, and invasion ability of the cells were verified by flow cytometry, cell scratch experiment, and Transwell experiment.The results of semiquantitative RT-PCR showed that there were significantly lower expression of miRNA-143 (p 0.01) and remarkably higher expressions of KRAS gene and KRAS protein (p 0.01) in pancreatic cancer tissues compared with cancer-adjacent tissues. The expression of miRNA-143 had no correlation with the patient's age and gender, but was closely related to the tumor size, clinical staging, and metastasis of lymph nodes. The detection with flow cytometry showed that cell apoptosis was significantly increased by overexpression of miRNA-143 in PANC-1 (p 0.01). The result of cell scratch experiment indicated that the migration ability of PANC-1 was reduced significantly by overexpression of miRNA-143 (p 0.01) and that of Transwell experiment manifested that the invasion ability of PANC-1 was decreased significantly by overexpression of miRNA-143 (p 0.01).The expression of miRNA-143 in pancreatic cancer tissues is significantly decreased. MiRNA-143 can promote cell apoptosis and regulate the process of pancreatic cancer by inhibiting the migration and invasion of pancreatic cancer cells.

KRAS (kirsten rat sarcoma viral oncogene) is a member of the RAS family. KRAS mutations are one of most dominant mutations in colorectal cancer (CRC). The impact of KRAS mutations on the prognosis and survival of CRC patients drives many research studies to explore potential therapeutics or target therapy for the KRAS mutant CRC. This review summarizes the current understanding of the pathological consequences of the KRAS mutations in the development of CRC; and the impact of the mutations on the response and the sensitivity to the current front-line chemotherapy. The current therapeutic strategies for treating KRAS mutant CRC, the difficulties and challenges will also be discussed.

Fine-needle aspiration (FNA) plays a key role in the early evaluation of patients with thyroid nodules; however, from 15% to 30% of FNA specimens are cytologically indeterminate. Molecular testing has proven useful when applied to indeterminate thyroid FNAs, and its use has been endorsed in the American Thyroid Association guidelines. In addition to the noncommercial ("in-house") application of v-Raf murine sarcoma viral oncogene homolog B1 (BRAF), rat sarcoma (RAS), rearranged in transformation/papillary thyroid carcinoma (RET/PTC), and peroxisome proliferator-activated receptor γ/paired box gene 8 (PPARγ/PAX8) testing, there are currently 3 commercially available molecular panels that vary in their relative reported performances, strengths, and limitations. Here, we discuss the role of molecular testing for indeterminate thyroid aspirates, taking into consideration the recent reclassification of the encapsulated follicular variant of papillary thyroid carcinoma (PTC) as "noninvasive follicular neoplasm with papillary-like nuclear features (NIFTP)." Cancer Cytopathol 2017;125(6 suppl):477-85. © 2017 American Cancer Society.

The research and treatment of non-small cell lung cancer (NSCLC) have achieved some important advances in recent years. Nonetheless, the overall survival rates for NSCLC remain low, indicating the importance to effectively develop new therapies and improve current approaches. The understanding of the function of different biomarkers involved in NSCLC progression, survival and response to therapy are important for the development of early detection tools and treatment options. Epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma viral oncogene homolog (K-RAS) are two of the main significant biomarkers for the management of NSCLC. Mutations in these genes were associated with development and response to therapies. For example, the use of small molecule tyrosine kinase (TK) inhibitors and immunotherapy has led to benefits in some, but not all patients with altered EGFR. In contrast, there is still no effective approved drug to act upon patients harbouring K-RAS mutations. In addition, K-RAS mutations have been associated with lack of activity of TK inhibitors. However, promising approaches aimed to inhibit mutant K-RAS are currently under study. Therefore, this review will discuss these approaches and also EGFR therapies, and hopefully, it will draw attention to the need of continued research in the field in order to improve the outcomes in NSCLC patients.

In our recent study, we demonstrated that oncogenic RAS (rat sarcoma)-mediated transformation and tumorigenesis are supported by transcriptional induction of a crucial antioxidant component, SLC7A11 (solute carrier family 7 member 11), otherwise known as XCT, a gene encoding the cystine/glutamate transporter. Our data highlight that this promotes the biosynthesis of glutathione, in turn allowing RAS transformed cells to mitigate tumorigenesis-linked oxidative stress.

The aim of the present study was to characterize a patient-derived in vitro 3D model (ie tumoroid) established from colorectal adenocarcinoma. This study investigated the growth rate of tumoroids and whether the Kirsten rat sarcoma (KRAS) mutations in the parental tumour accelerate this rate. The tumoroids were established from surgical resections of primary and metastatic colorectal adenocarcinoma from 26 patients. The in vitro growth rate of these tumoroids was monitored by automated imaging and recorded as relative growth rate. The KRAS hotspot mutations were investigated on the parental tumours by Ion Torrent((TM)) next-generation sequencing. The KRAS mutations were detected in 58% of the parental tumours, and a significantly higher growth rate was observed for tumoroids established from the KRAS-mutated tumours compared to wild-type tumours (P

Rat sarcoma viral oncogene (RAS) is one of the most well-known tumor genes implicated in the oncological and surgical management of patients with colorectal liver metastases (CLM). More recently, RAS mutational status has also emerged as a relevant factor affecting the oncological outcomes of CLM treated with ablation procedures, a well-established local therapy modality routinely utilized in the oligometastatic disease (OMD) setting. Available evidence suggests that RAS mutation is a prognosticator of shorter local tumor progression free survival (LTPFS) following liver ablation, and that mutant RAS patients with CLM treated with ablation should have wider minimal ablation margins. In this review, we aim to discuss the current literature on the influence of RAS mutational status on ablation outcomes, as well to provide a perspective on the future research on the impact of tumor molecular biology on liver ablation procedures and the potential synergies between local and systemic therapies.

Background: We investigated the associations between v-Raf murine sarcoma viral oncogene homolog B1 (BRAFV600E, henceforth BRAF) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations and colorectal cancer (CRC) prognosis, using The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GSE39582) datasets. Materials and Methods: The effects of BRAF and KRAS mutations on overall survival (OS) and disease-free survival (DFS) of CRC were evaluated. Results: The mutational status of BRAF and KRAS genes was not associated with overall survival (OS) or DFS of the CRC patients drawn from the TCGA database. The 3-year OS and DFS rates of the BRAF mutation (+) vs. mutation (−) groups were 92.6% vs. 90.4% and 79.7% vs. 68.4%, respectively. The 3-year OS and DFS rates of the KRAS mutation (+) vs. mutation (−) groups were 90.4% vs. 90.5% and 65.3% vs. 73.5%, respectively. In stage II patients, however, the 3-year OS rate was lower in the BRAF mutation (+) group than in the mutation (−) group (85.5% vs. 97.7%, p < 0.001). The mutational status of BRAF genes of 497 CRC patients drawn from the GSE39582 database was not associated with OS or DFS. The 3-year OS and DFS rates of BRAF mutation (+) vs. mutation (−) groups were 75.7% vs. 78.9% and 73.6% vs. 71.1%, respectively. However, KRAS mutational status had an effect on 3-year OS rate (71.9% mutation (+) vs. 83% mutation (−), p = 0.05) and DFS rate (66.3% mutation (+) vs. 74.6% mutation (−), p = 0.013). Conclusions: We found no consistent association between the mutational status of BRAF nor KRAS and the OS and DFS of CRC patients from the TCGA and GSE39582 databases. Studies with longer-term records and larger patient numbers may be necessary to expound the influence of BRAF and KRAS mutations on the outcomes of CRC.

Simple Summary Since the Kirsten rat sarcoma viral oncogene homolog (KRAS) is mutated in about 25% of all human cancers and is at the center of pathways involved in tumorigenesis, it is necessary to compile and highlight the novel therapeutic strategies behind targeting this oncoprotein in cancer. Over the years, many have studied various methods to directly target KRAS with no success. Fortunately, there has been more success in targeting other proteins along the RAS pathway to yield a therapeutic response. However, some recent findings show promising results indicating that we are one step closer to developing an effective inhibitor that directly targets KRAS. The review presented here summarizes these recent findings and emphasizes the need to continue the search for the most optimal KRAS inhibitor that can be used to treat and potentially even cure certain tumor types. Abstract The Kirsten rat sarcoma viral oncogene homolog (KRAS) is mutated in approximately 25% of all human cancers and is known to be a major player promoting and maintaining tumorigenesis through the RAS/MAPK pathway. Over the years, a large number of studies have identified strategies at different regulatory levels to tackle this ‘difficult-to-target’ oncoprotein. Yet, the most ideal strategy to overcome KRAS and its downstream effects has yet to be uncovered. This review summarizes the role of KRAS activating mutations in multiple cancer types as well as the key findings for potential strategies inhibiting its oncogenic behavior. A comprehensive analysis of the different pathways and mechanisms associated with KRAS activity in tumors will ultimately pave the way for promising future work that will identify optimum therapeutic strategies.

Objective: To assess the characteristics of Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations and investigated whether all KRAS mutations predict poor prognosis in patients with unresectable colorectal liver metastasis (CRLM). Methods: Correlations between KRAS-mutation status and clinicopathological characteristics of 93 patients with unresectable CRLM at our institution between 2010 and 2018 were retrospectively analyzed. Kaplan–Meier and Cox proportional hazard models were used to evaluate the prognostic significance of KRAS mutations. Results: KRAS were primarily single-point mutations, identified in 41.9% of patients. There were no significant differences in clinicopathological characteristics between wild-type KRAS and mutant KRAS. Patients with mutant KRAS had significantly worse overall survival (OS) and progression-free survival (PFS) than those with wild-type KRAS. Moreover, patients with codon 12 mutations had worse OS and PFS than those with wild-type KRAS, whereas mutations in codon 13 were not associated with a worse prognosis. Among the 5 most common mutations in codons 12, G12V, and G12D were associated with worse OS, furthermore, G12C mutation seemed to associated with worse PFS than patients with wild-type KRAS. Conclusion: KRAS codon 12 mutations were predictive for a poor prognosis in patients with unresectable CRLM. G12D and G12V mutations were associated with worse OS, whereas G12C mutation seemed to be associated with decreased PFS.

Activating Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are the most common and frequent changes observed in pancreatic cancer. This study aimed to determine the frequency and extent of intratumoral and metastatic lymph node KRAS mutation heterogeneity of resected pancreatic ductal adenocarcinoma.Tumor tissues macrodissected from tumor centers, invasion fronts (n = 97), and lymph nodes (n = 11) were subjected to DNA extraction and mutation analysis of KRAS codons 12 and 13 by pyrosequencing.Activating mutations in codon 12 of KRAS were detected in 90 (92.8%) tumor centers. No mutations were detected in KRAS codon 13 in any patient. After a comparison of tumor centers and invasion fronts, intratumoral heterogeneity of KRAS was observed only in 4 (4.1%) cases. Additional invasion front tumor analysis revealed the same mutation status consistent with each tumor center. No heterogeneity was observed between primary tumors and metastatic lymph nodes.Intratumoral heterogeneity of the KRAS mutational status is rare in pancreatic ductal adenocarcinoma. In addition, no KRAS heterogeneity between primary tumors and metastatic lymph nodes was detected in this study. This finding is consistent with the hypothesis that oncogenic activation of KRAS is the first driver mutation in pancreatic cancer.

TPS3661 Background: Kirsten rat sarcoma viral oncogene homolog (KRAS) p.G12C mutation has been identified as a driver oncogenic mutation in several solid tumors (eg, non-small cell lung cancer [NSCLC], colorectal cancer [CRC]). Development of therapies targeting KRASG12C has been unsuccessful. AMG 510 is a specific and irreversible small molecule inhibitor of KRASG12C. A first-in-human clinical trial of AMG 510 monotherapy in patients with KRAS p.G12C mutant solid tumors is currently ongoing. AMG 510 in combination with additional anticancer therapies may lead to enhanced antitumor efficacy. This study is a master protocol designed to evaluate multiple investigational regimens of AMG 510 in patients with KRAS p.G12C mutant solid tumors. Here, we present two combination cohorts of AMG 510 with a mitogen-activated protein kinase kinase (MEK) inhibitor and an investigational anti-programmed cell death protein-1 (PD-1) therapy, respectively. Additional combination cohorts will be presented at the meeting. Methods: This is a phase 1b, open-label study evaluating AMG 510 in combination with a MEK inhibitor or an investigational anti-PD-1 therapy in pts with KRAS p.G12C mutant solid tumors. The dose exploration phase (part 1; n=20) will evaluate the safety and tolerability of AMG 510 in combination with the MEK inhibitor or anti-PD-1 therapy; this will be followed by a dose expansion phase (part 2; n=40) to verify the safety and tolerability profile of AMG 510 combination therapies and assess antitumor efficacy. Key eligibility criteria include locally-advanced or metastatic malignancy with KRAS p.G12C mutation identified through molecular testing and at least one or multiple lines of prior systemic therapy (eg, ≥2 for advanced/metastatic colorectal cancer). Primary endpoints include dose-limiting toxicities, treatment-emergent or -related adverse events. Secondary endpoints include pharmacokinetic parameters of combination regimens, disease control rate, duration of response, progression-free survival, and duration of stable disease (measured by computed tomography or magnetic resonance imaging and assessed per RECIST 1.1). The study began enrolling pts in December 2019 and is ongoing. For more information, please contact Amgen Medical Information: medinfo@amgen.com . Clinical trial information: NCT04185883 .

4018 Background: Kirsten rat sarcoma viral oncogene homolog (KRAS) p.G12C mutation is associated with poor prognosis in colorectal cancer (CRC). AMG 510 is a first-in-class small molecule that specifically and irreversibly inhibits KRASG12C by locking it in the inactive guanosine diphosphate-bound state. In a previous interim analysis of the phase 1, first-in-human trial of AMG 510, we observed a favorable safety profile and preliminary antitumor activity in patients (pts) with advanced solid tumors harboring KRAS p.G12C. Here, we present updated data in pts with CRC. Methods: Key inclusion criteria were KRAS p.G12C mutation identified through molecular testing, measurable disease, and progression on standard therapy. Primary endpoint was safety. Secondary endpoints were objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), as assessed per RECIST 1.1, and overall survival (OS). Oral daily doses of 180, 360, 720, and 960mg were tested in the dose escalation phase, and 960mg dose was selected for the expansion phase. Results: As of Jan 8, 2020, 42 pts with CRC (21 female [50%], median age: 57.5 years [range: 33–82]) were enrolled and dosed (25 on 960mg). All pts received prior systemic therapies; 19 pts (45.2%) received > 3 prior lines. Median follow-up was 7.9 months (mos) (range: 4.2–15.9). 13 pts (31.0%) died, and 8 pts (19.0%) remained on treatment (tx). 22 (52.4%) and 8 (19.0%) pts had remained on tx for more than 3 and 6 months, respectively. Progressive disease was the most common reason for tx discontinuation. 20 pts (47.6%) had tx-related adverse events (TRAEs): 18 (42.9%) had grade 2 or lower TRAEs; 2 (4.8%) had grade 3 TRAEs, which were diarrhea (2.4%) and anemia (2.4%). There were no dose-limiting toxicities, fatal TRAEs, or TRAEs leading to tx discontinuation. Overall, ORR and DCR were 7.1% (3/42) and 76.2% (32/42), respectively. At 960mg, ORR and DCR were 12.0% (3/25) and 80.0% (20/25). 3 pts with PR had duration of response of 1.5, 4.2, and 4.3 months, respectively, and their responses were still ongoing at data cutoff. In all pts treated with all doses, median duration of stable disease was 4.2 mos (range: 2.5[+]–11.0). PFS/OS will be reported. Conclusions: In pts with heavily pretreated KRAS p.G12C mutant CRC, AMG 510 monotherapy was well tolerated, with the majority of pts achieving disease control. Study is ongoing. Clinical trial information: NCT03600883 .

3547 Background: Kirsten rat sarcoma viral oncogene homolog (KRAS) is the most commonly mutated proto-oncogene identified in cancer and still remains an arduous therapeutic challenge. Recently, KRASG12C mutation has become special interest since it has now been considered potentially druggable after the introduction of covalent small-molecule KRASG12C inhibitors. Advances in next-generation sequencing (NGS) and embracing utilization of ctDNA have uncovered more genetic alterations in many cancers. We present a comprehensive analysis on the prevalence of KRASG12C mutations identified by ctDNA. Methods: We conducted a 5-year (July 2014 to June 2019) retrospective review of ctDNA NGS analysis in the Guardant360 CLIA database inclusive of treatment-naïve and previously treated patients with metastatic solid tumors. Data were retrieved from the 80,911 unique patients with ctDNA detected. Clonality and co-occurrence of cancer type were analyzed. Clonality was defined as variant allele fraction(AF) / maximum somatic AF in the sample. Results: 80,911 patients, which included more than 100 tumor histologies, were identified. 2,985 patients (3.7%) with > 40 tumor types had KRASG12C mutations identified in ctDNA. KRASG12C prevalence by cancer type were as follows: sarcomatoid lung carcinoma (13.5%), lung cancer NOS (9%), large cell lung carcinoma (9%), lung adenocarcinoma (7.4%), NSCLC (6.9%), carcinoma of unknown primary (CUP) (4.1%), lung carcinoid (4%), CRC (3.5%), squamous cell lung carcinoma (2%), small cell lung carcinoma (1.5%), pancreatic ductal adenocarcinoma (PDAC) (1.2%), cholangiocarcinoma (1.2%), bladder cancer (0.6%), ovarian cancer (0.6%) and breast cancer (0.3%). 53 additional patients with KRASG12C were identified across 24 other tumor types. The KRASG12C mutation was found to be clonal (clonality > 0.9%) in the majority of patients with lung adenocarcinoma, NSCLC, CUP, squamous cell lung carcinoma, and PDAC, compared to patients with CRC and breast cancer who had bimodal distribution of clonal and sub clonal mutations. Conclusions: To our knowledge, this is the largest analysis on the prevalence of KRASG12C mutations identified by ctDNA. Our study demonstrated the feasibility of utilizing ctDNA to identify KRASG12C mutations across solid tumors with the highest prevalence in lung cancer as previously reported in tissue. The clonality information available from ctDNA-based genotyping may provide insights into the clinical efficacy of targeting KRASG12C in different tumor types.

3511 Background: Kirsten rat sarcoma viral oncogene homolog ( KRAS) p.G12C mutation occurs in approximately 13% of NSCLC and 1%–3% of CRC and other solid tumors. AMG 510 is a first-in-class small molecule that specifically and irreversibly inhibits KRASG12C. Previously, AMG 510 showed preliminary antitumor activity and favorable tolerability in pts with KRAS p.G12C mutant NSCLC or CRC in the phase 1, first-in-human trial. Here, we report results in pts with other tumor types from the same trial. Methods: This study evaluates AMG 510 in pts with locally-advanced or metastatic KRAS p.G12C mutant solid tumors. Key inclusion criteria: KRAS p.G12C mutation via local testing and prior systemic anticancer treatment (tx). Oral daily doses of 180, 360, 720, and 960 mg were tested in the dose escalation, and 960 mg was selected for expansion. Primary endpoint is safety; key secondary endpoints include pharmacokinetics and objective response rate as assessed per RECIST 1.1. Response is assessed every 6 weeks (wks) for 24 wks then every 12 wks thereafter. Results: As of January 8, 2020, 25 pts (9 female, median age 60 years [range: 40–75]) with tumor types categorized by investigators as histology other than NSCLC and CRC were enrolled and dosed (10 pancreatic cancer, 4 appendiceal cancer, 2 endometrial cancer, 2 unknown primary cancer, 1 bile duct cancer, 1 sinonasal cancer, 1 ampullary cancer, 1 small bowel cancer, 1 melanoma, 1 small cell lung cancer, and 1 esophageal cancer). 23 pts received 960 mg dose. 20 pts (80.0%) had ≥2 prior lines of tx. At data cutoff, 13 pts (52.0%) remained on tx; 9 (36.0%) and 3 (12.0%) pts remained on tx for ≥3 and ≥6 months, respectively. Median follow up was 4.3 months (range: 0.1–12.6). Tx-related adverse events (TRAEs) occurred in 9 pts (36.0%). 2 pts (8.0%) had grade 3 TRAEs, including diarrhea (1/25) and pneumonia (1/25, serious AE). No dose-limiting toxicities, grade ≥4, or fatal TRAEs were reported. No TRAEs led to tx discontinuation. 3 pts had not been followed up for ≥7 wks by the data cutoff. 22 pts were followed up for ≥7 wks, and their best overall responses were: 3 confirmed partial response (1 appendiceal, 1 melanoma, and 1 endometrial), 13 stable disease (6 pancreatic, 2 appendiceal, 1 ampullary, 1 bile duct, 1 endometrial, 1 sinonasal, and 1 unknown primary), and 6 progressive disease. Conclusions: AMG 510 was well tolerated and demonstrated clinical activity in pts with advanced KRAS p.G12C mutant solid tumors other than NSCLC and CRC. Clinical trial information: NCT03600883 .

[Image: see text] Epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma viral oncogene homolog (KRAS) oncogenic mutations are leading causes for lung cancer. Extensive drug discovery efforts targeting EGFR have led to the discovery and FDA approval of both reversible and covalent inhibitors. Second and third generation covalent inhibitors for EGFR have also been described, with the latter targeting specific emerging mutations. After decades of extensive effort, KRAS is widely regarded as an intractable therapeutic target; however, recent publications suggest covalent inhibition is a promising strategy to deliver inhibitors of the KRAS(G12C) mutation.

Protein catalyzed capture (PCC) agents are synthetic antibody surrogates that can target a wide variety of biologically relevant proteins. As a step towards developing a high-throughput PCC pipeline we report on the preparation of a barcoded rapid assay platform for the analysis of hits from PCC agent library screens. The platform is constructed by first surface patterning a micrometer scale barcode composed of orthogonal ssDNA strands onto a glass slide. The slide is then partitioned into microwells, each of which contains multiple copies of the full barcode. Biotinylated candidate PCCs from a click screen are assembled onto the barcode stripes using a complementary ssDNA-encoded cysteine-modified streptavidin library. This platform was employed to evaluate candidate PCC ligands identified from an epitope targeted in situ click screen against the two conserved allosteric switch regions of the KRas protein. A single microchip was utilized for the simultaneous evaluation of fifteen PCC candidate fractions under more than a dozen different assay conditions. The platform also permitted more than a 10-fold savings in time and a more than 100-fold reduction in biological and chemical reagents relative to traditional multi-well plate assays. The best ligand was shown to exhibit an in vitro inhibition constant (IC(50)) of ~24 μM.

Background/aim The feasibility and oncological outcomes of treatment with TAS-102, that is recommended as third-line chemotherapy for patients with metastatic colorectal cancer (mCRC), remain unknown. Patients and methods Between 2013 and 2015, seven patients (five males, two females) with mCRC who were administered TAS-102 as third-line chemotherapy at our Institution were retrospectively studied. During the same period, seven patients with mCRC with Kirsten rat sarcoma viral oncogene homolog (KRAS) wild-type primary lesions who were administered irinotecan with panitumumab comprised the control group. Results The duration of third-line chemotherapy in the TAS-102 group was 217.0 (range=136-337) days compared to 226.9 (range=122-335) days in the control group, with no significant difference in the duration of administration between the two groups. No significant difference in overall survival was identified between the two groups No serious adverse effects were encountered in either group. Conclusion TAS-102 may be suitable as third-line chemotherapy for patients with mCRC.

Effectiveness of a new photosensitizer (PS) liposomal amidoaminchlorine for PDT was studied on a tumor model of rat sarcoma М-1. The research objective: to define parameters of PS minimum effective dose and laser irradiation to achieve complete regression of the tumor. Dynamics of PS accumulation in tumor and healthy tissue was studied to define the PDT time course and antitumor efficiency of different PS doses and various parameters of laser irradiation. The study results defined the optimum term for PDT and minimally effective PS dose and established the parameters for laser irradiation.

BACKGROUND: In the NORDIC-7.5 trial, how cetuximab might safely and conveniently be added to an intermittent treatment strategy in patients with prospectively selected Kirsten rat sarcoma viral oncogene homolog wild type (KRASwt) metastatic colorectal cancer (mCRC) was investigated. Patients were treated in a multicenter phase II trial with cetuximab in combination with the Nordic bolus FLOX (oxaliplatin, 5-fluorouracil, and folinic acid) for 4 months followed by maintenance cetuximab.PATIENTS AND METHODS: Patients had KRASwt, nonresectable mCRC, no previous chemotherapy, and Eastern Cooperative Group performance status of 0 to 2. Patients received 8 courses of Nordic FLOX (oxaliplatin 85 mg/m(2) over 1 hour on day 1, and 5-fluorouracil 500 mg/m(2) as a bolus injection, followed 30 minutes later with bolus folinic acid 60 mg/m(2) on days 1 and 2). Cetuximab was administered every 2 weeks at a dose of 500 mg/m(2) for 16 weeks followed by cetuximab as maintenance therapy until disease progression.RESULTS: Between July 2008 and September 2010, 152 KRASwt patients were included. The response rate was 62% (95% confidence interval [CI], 54%-69%), median progression-free survival was 8.0 months (95% CI, 7.5-8.9) and median overall survival was 23.2 (95% CI, 18.1-27.4) months. Twenty-one patients (14%) had later R0-resection of metastasis. FLOX with cetuximab was reintroduced in 47 of 85 patients (55%). The most common Grade 3/4 nonhematologic adverse events were diarrhea in 14 patients (9%), skin rash in 13 patients (9%), infection without neutropenia in 11 patients (7%), and fatigue in 11 patients (7%).CONCLUSION: In a prospectively selected KRASwt population, biweekly cetuximab was safely integrated in an intermittent chemotherapy strategy and might have added to a longer chemotherapy-free interval. However, the combination of biweekly cetuximab with chemotherapy needs to be validated in trials using FOLFOX (oxaliplatin, fluorouracil, and leucovorin) or FOLFIRI (irinotecan, fluorouracil, and leucovorin).

Local recurrence of pancreatic cancer (PC) can occur in the pancreatic remnant. In addition, new primary PC can develop in the remnant. There are limited data available regarding this so-called remnant PC. The aim of this review was to describe the characteristics and therapeutic strategy regarding remnant PC. A literature search was performed using Medline published in English according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The incidence of remnant PC has been reported to be 3% to 5%. It is difficult to distinguish local recurrence from new primary PC. Genetic diagnosis such as Kirsten rat sarcoma viral oncogene homolog mutation may resolve this problem. For patients with remnant PC, repeated pancreatectomy can be performed. Residual total pancreatectomy is the most common procedure. Recent studies have described the safety of the operation because of recent surgical progress and perioperative care. The patients with remnant PC without distant metastasis have shown good long-term outcomes, especially those who underwent repeated pancreatectomy. Adjuvant chemotherapy may contribute to longer survival. In conclusion, this review found that both local recurrence and new primary PC can develop in the pancreatic remnant. Repeated pancreatectomy for the remnant PC is a feasible procedure and can prolong patient survival.

Introduction In 2008, the National Comprehensive Cancer Network guidelines were revised in light of the identification of the Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) gene as a biomarker of nonresponse to epidermal growth factor receptor inhibitors. This study sought to describe and compare real-world treatment patterns of metastatic colorectal cancer (mCRC) according to KRAS genotype in community-based oncology practices in the United States. Materials and Methods Data from the ACORN (ACORN LLC, Memphis, TN) electronic medical record data warehouse, containing data of approximately 180,000 patients from 12 oncology practices across the United States were used. Records of adult patients with mCRC who had undergone KRAS testing between January 2008 and December 2011 were evaluated. Patient demographic characteristics, KRAS genotype, and treatment patterns were identified and compared. Results Six hundred forty-eight mCRC patients who were tested for KRAS were identified. Of these, 48.1% had wild type (WT), 42.3% mutant, and 9.6% unknown genotypes. Most patients (72.1%) were tested in 2009 or later, after the guideline revision. Bevacizumab-containing combinations were the most common first-line regimens in KRAS mutant and WT patients. Approximately 90% of patients received at least 1 line of therapy, however, WT patients received significantly more lines of therapy than KRAS mutant patients (2.6 ± 1.5 vs. 2.1 ± 1.2; P Conclusions KRAS WT and mutant genotypes had similar first-line regimens; however, WT patients received more lines of therapy. Although there does not appear to be a lag between changes in guidelines and treatment practice, professional and government organizations must keep up with the changing science and disseminate this information to oncologists in a timely manner.

While the significance of carcinoembryonic antigen (CEA), lactate dehydrogenase (LDH), and Kirsten rat sarcoma (KRAS) status as individual prognostic factors for patients with metastatic colorectal cancer has been addressed, the relationship and interdependence between these prognostic factors on survival is limited.Patients with unresectable colorectal liver metastases with known KRAS status, and with baseline CEA and LDH levels who were treated with hepatic arterial infusion and systemic chemotherapy were identified. Patients were divided into two groups: hepatic-only disease and extra-hepatic disease.A total of 193 patients were included: 121 with hepatic-only and 72 with extra-hepatic disease. In the hepatic-only group, median overall survival (OS) was 55 months. On multivariate analysis, KRAS mutated tumors (HR 1.7, P 0.05), LDH200 U/L (HR 2.0, P 0.05), and prior chemotherapy (HR 2.1, P 0.05) had lower OS. In patients with extra-hepatic disease, median OS was 32 months. On multivariate analysis, baseline CEA200 ng/mL (HR 2.1, P = 0.051), LDH200 U/L (HR 3.8, P 0.05), and right-sided tumors (HR 2.8, P 0.05) had lower OS.This analysis verifies two distinct patterns in terms of biomarkers in patients with unresectable colorectal liver metastases. In patients with hepatic-only disease, KRAS mutation and elevated LDH negatively influenced survival. In patients with extra-hepatic disease, elevated LDH negatively impacted survival.

The Rat Sarcoma (RAS) GTPAse-mediated extracellular signal-regulated kinase (ERK) pathway regulates multiple biological processes across metazoans. In particular during Caenorhabditis elegans oogenesis, ERK signaling has been shown to regulate over seven distinct biological processes in a temporal and sequential manner. To fully elucidate how ERK signaling cascade orchestrates these different biological processes in vivo, identification of the direct functional substrates of the pathway is critical. This chapter describes the methods that were used to identify ERK substrates in a global manner and study their functions in the germline. These approaches can also be generally applied to study ERK-dependent biological processes in other systems.

e15144 Background: The status of mutations in the rat sarcoma viral oncogene homolog ( RAS) family of genes, which includes Kirsten RAS ( KRAS) and Neuroblastoma RAS ( NRAS) predicts response to anti-EGFR therapies in metastatic colorectal cancer (mCRC) patients. Current treatment guidelines recommend all mCRC patients to receive RAS testing prior to initiating treatment with an anti-EGFR agent. This study sought to establish estimates of RAS testing among mCRC patients in the US prior to initiation of first and third lines of treatment, and to describe median survival by treatment groups. Methods: Data from the Oncology Services Comprehensive Electronic Records (OSCER) 2.0 dataset were utilized. Patients diagnosed with mCRC between January 1, 2011 and July 31, 2017 were eligible. Patients were followed for up to 1 year, or until death, following their mCRC diagnosis. Results: A total of 17,387 mCRC patients were included in the analysis, among which 69% were RAS tested and 31% were never tested. Among the RAS tested patients, 23% were tested prior to their mCRC diagnosis 60% received RAS testing following mCRC diagnosis but prior to first line of treatment, 3% were tested following first line treatment but prior to third line, and the remaining 14% were tested following third line. Demographic variables did not differ between tested and untested groups, overall and by line of treatment. The overall median survival of RAS WT patients was 31.1 months (95% CI: 30.0, 32.4). MCRC patients who were not RAS tested had a lower median survival of 20.7 months (95% CI: 19.1, 22.5). Conclusions: The timing of when patients are being tested varies greatly. While nearly 70% of patients had a RAS test, approximately 30% failed to be tested, identifying a large gap in testing practices. Universal RAS testing provides patients and their physicians with knowledge of their anti-EGFR treatment options and may result in improved survival.