Prognostic Value of KRAS Exon 3 and Exon 4 Mutations in Colorectal Cancer Patients

Association of various RAS codon mutations and prognostic outcomes of patients with colorectal liver metastases after hepatectomy

PURPOSE

The prognostic and predictive value of RAS mutations in patients with colorectal liver metastases (CRLM) who have undergone hepatectomy holds substantial importance. The present study aimed to investigate the impact of different RAS codon mutations on long-term survival in CRLM patients.

METHODS

A retrospective analysis was conducted on clinicopathological data from 399 CRLM patients with RAS mutations who underwent hepatectomy between January 2000 and December 2020. The RAS mutation gene status was assessed in KRAS codons (G12, G13, Q61, and A146) and NRAS codons (G12, G13, and Q61). Survival curves were generated using the Kaplan-Meier plotter and compared using the log-rank test. Univariate and multivariate analyses were performed to analyze the clinicopathological data.

RESULTS

In the entire cohort, patients with KRAS G12 mutations exhibited the most favorable prognosis (p = 0.018). Comparatively, patients harboring KRAS Q61 mutations experienced poorer overall survival (OS) with a median of 15 months versus 33 months (p = 0.011) when compared to those with KRAS G12 mutations. Moreover, patients with NRAS Q61 mutations also showed decreased OS with a median of 26 months versus 33 months (p = 0.020) in comparison to KRAS G12 mutation patients. The results of multivariate analysis showed that both KRAS Q61 mutation (HR 2.130; 95% CI 1.088-4.168; p = 0.027) and NRAS Q61 mutation (HR 2.877; 95% CI 1.398-5.922; p = 0.004) were independent influencing factors of OS. Based on all identified risk factors, patients with RAS mutation were divided into high-risk and low-risk groups. Notably, in the high-risk group, the incorporation of postoperative chemotherapy was associated with longer OS, while it did not improve the survival of patients in the low-risk group.

CONCLUSIONS

KRAS Q61 and NRAS Q61 mutations are promising predictors for OS in CRLM patients after hepatectomy. Postoperative chemotherapy may significantly benefit CRLM patients with RAS mutations, particularly those identified as high-risk.

KRAS Mutation Status in Bulgarian Patients with Advanced and Metastatic Colorectal Cancer

RAS somatic variants are predictors of resistance to anti-EGFR therapy for colorectal cancer (CRC) and affect the outcome of the disease. Our study aimed to evaluate the frequency of RAS, with a focus on KRAS variants, and their association with tumor location and some clinicopathological characteristics in Bulgarian CRC patients. We prospectively investigated 236 patients with advanced and metastatic CRC. Genomic DNA was extracted from FFPE tumor tissue samples, and commercially available kits were used to detect RAS gene somatic mutations via real-time PCR. A total of 115 (48.73%) patients tested positive for RAS mutations, with 106 (44.92%) testing positive for KRAS mutations. The most common mutation in exon 2 was c.35G>T p.Gly12Val (32.56%). We did not find a significant difference in KRAS mutation frequency according to tumor location. However, patients with a mutation in exon 4 of KRAS were 3.23 times more likely to have a tumor in the rectum than in other locations (95% CI: 1.19-8.72, p = 0.021). Studying the link between tumor location and KRAS mutations in exon 4 is crucial for better characterizing CRC patients. Further research with larger cohorts, especially in rectal cancer patients, could provide valuable insights for patient follow-up and treatment selection.

Targeted Therapies in Colorectal Cancer: Recent Advances in Biomarkers, Landmark Trials, and Future Perspectives

In 2022, approximately 600,000 cancer deaths were expected; more than 50,000 of those deaths would be from colorectal cancer (CRC). The CRC mortality rate in the US has decreased in recent decades, with a 51% drop between 1976 and 2014. This drop is attributed, in part, to the tremendous therapeutic improvements, especially after the 2000s, in addition to increased social awareness regarding risk factors and diagnostic improvement. Five-fluorouracil, irinotecan, capecitabine, and later oxaliplatin were the mainstays of mCRC treatment from the 1960s to 2002. Since then, more than a dozen drugs have been approved for the disease, betting on a new chapter in medicine, precision oncology, which uses patient and tumor characteristics to guide the therapeutic choice. Thus, this review will summarize the current literature on targeted therapies, highlighting the molecular biomarkers involved and their pathways.

KRAS mutated colorectal cancers with or without PIK3CA mutations: Clinical and molecular profiles inform current and future therapeutics

BACKGROUND

Colorectal cancer is one of the most prevalent malignancies and its molecular pathogenesis has been intensely investigated for several decades. As a result, great progress has been made and targeted therapies have been introduced in the clinic. This paper examines colorectal cancers based on two of the most common molecular alterations, KRAS and PIK3CA mutations as a basis for therapeutic targeting.

METHODS

Two publicly available genomic series with clinical data were evaluated for prevalence and characteristics of cases with and without KRAS and PIK3CA mutations and the literature was reviewed for relevant information on the therapeutic implication of these alterations as well as other coincident alterations to derive therapeutic individualized options of targeted treatments.

RESULTS

Colorectal cancers without KRAS and PIK3CA mutations represent the most prevalent group (48% to 58% of patients) and present therapeutic targeted opportunities with BRAF inhibitors and immune checkpoint inhibitors in the subsets with BRAF mutations (15% to 22%) and Microsatellite Instability (MSI, 14% to 16%), respectively. The second most prevalent sub-set, with KRAS mutations and PIK3CA wild type, representing 20% to 25% of patients, has currently few targeted options, besides specific KRAS G12C inhibitors for the small percentage of cases (9%-10%) that bear this mutation. Cancers with KRAS wild type and PIK3CA mutations are observed in 12% to 14% of colorectal cancer patients, harbor the highest percentage of cases with BRAF mutations and Microsatellite Instability (MSI), and are candidates for the respective targeted therapies. New targeted therapies in development, such as ATR inhibitors could be effective in cases with ATM mutations and ARID1A mutations that are also most prevalent in this sub-group (14% to 22% and 30%, respectively). KRAS and PIK3CA double mutant cancers have also few targeted options currently and could benefit from combination therapies with PI3K inhibitors and new KRAS inhibitors in development.

CONCLUSION

The backbone of common KRAS and PIK3CA mutations is a rational frame for development of therapeutic algorithms in colorectal cancer and can help guide new drug therapies development. In addition, the prevalence of different molecular groups presented here may help with planning of combination clinical trials by providing estimations of sub-sets with more than one alteration.

Rapid Malignant Transformation of Tubulovillous Adenoma, Initially Presenting as McKittrick-Wheelock Syndrome: A Case Report

Most cases of colorectal cancer develop from adenomatous polyps, slowly progressing within an average period of 8-10 years. McKittrick-Wheelock syndrome (MKWS) is a rare manifestation of tubulovillous adenoma. It generally presents as hypersecretory diarrhea with severe electrolyte and fluid depletion. Roughly, 5% of the published cases have reported malignant histopathology associated with MKWS, with little to no data regarding the malignant transformation process of those patients. Our patient was a 53-year-old Asian woman suffering from chronic secretory diarrhea, resulting in severe volume, electrolyte depletion, and prerenal azotemia, consistent for MKWS. Her symptoms initially improved with sulfasalazine but eventually worsened. She demonstrated signs of systemic (elevated leukocyte, CRP, and LDH) and local inflammation (dense lymphocyte infiltration in colorectal tissue) throughout the course of her disease. Serial pathological results showed rapid neoplastic progression of adenomatous polyp to adenocarcinoma within 1 year period. Surgical resection resulted in complete symptom resolution. Molecular examination showed a favorable profile of exon 4 Kirsten rat sarcoma viral oncogene homolog mutation, normal NRAS, BRAF, CDX2, and CK20 expressions. Her molecular pattern did not reflect the profile of an aggressive disease, suggesting the possibility of oncogenic processes outside the major pathways of adenoma to carcinoma progression. Chronic inflammation is a well-established risk factor for colorectal cancer, and prostaglandin E2 (PGE2) has been observed as one of the key regulators of tumor initiation and growth. PGE2 is also responsible for hypersecretory diarrhea associated with MKWS.

Mutations matter: An observational study of the prognostic and predictive value of KRAS mutations in metastatic colorectal cancer

BACKGROUND

About half of metastatic colorectal cancers (CRCs) harbor Rat Sarcoma (RAS) activating mutations as oncogenic driver, but the prognostic role of RAS mutations is not fully elucidated. Interestingly, specific hotspot mutations have been identified as potential candidates for novel targeted therapies in several malignancies as per G12C. This study aims at evaluating the association between KRAS hotspot mutations and patient characteristics, prognosis and response to antiangiogenic drugs.

METHODS

Data from RAS-mutated CRC patients referred to Careggi University Hospital, between January 2017 and April 2022 were retrospectively and prospectively collected. Tumor samples were assessed for RAS mutation status using MALDI-TOF Mass Spectrometry, Myriapod NGS-56G Onco Panel, or Myriapod NGS Cancer Panel DNA.

RESULTS

Among 1047 patients with available RAS mutational status, 183 KRAS-mutated patients with advanced CRC had adequate data for clinicopathological and survival analysis. KRAS mutations occurred at codon 12 in 67.2% of cases, codon 13 in 23.5%, codon 61 in 2.2%, and other codons in 8.2%. G12C mutation was identified in 7.1% of patients and exon 4 mutations in 7.1%. KRAS G12D mutation, as compared to other mutations, was significantly associated with liver metastases (1-sided p=0.005) and male sex (1-sided p=0.039), KRAS G12C mutation with peritoneal metastases (1-sided p=0.035), KRAS G12V mutation with female sex (1-sided p=0.025) and no surgery for primary tumor (1-sided p=0.005). No associations were observed between specific KRAS variants and age, ECOG PS, site of primary tumor, pattern of recurrence for resected patients, and lung, distant lymph node, bone, or brain metastases.Overall survival (OS) was significantly longer in patients with KRAS exon 4 mutations than in those with other KRAS mutations (mOS 43.6 months vs 20.6 months; HR 0.45 [0.21-0.99], p=0.04). No difference in survival was observed for mutations at codon 12/13/61 (p=0.1). Treatment with bevacizumab (BV) increased significatively mPFS (p=0.036) and mOS (p=0.019) of the entire population with a substantial benefit in mOS for G12V mutation (p=0.031).

CONCLUSIONS

Patterns of presentation and prognosis among patients with specific RAS hotspot mutations deserve to be extensively studied in large datasets, with a specific attention to the uncommon isoforms and the role of anti-angiogenic drugs.

Multivariate Risk Analysis of RAS, BRAF and EGFR Mutations Allelic Frequency and Coexistence as Colorectal Cancer Predictive Biomarkers

Simple Summary

The colorectal cancer (CRC) stage and evolution should be described by biomarker profiles. In 60 CRC cases, KRAS, NRAS, BRAF, and EGFR mutations were analyzed by droplet digital PCR (ddPCR). KRAS G12/G13 mutation was present in all patients with variable allelic frequencies. KRAS Q61 mutation was correlated with tumor invasion beyond the subserosa and poor differentiation, both associated with worst prognosis. Tumors with NRAS and BRAF mutations were prevalently localized on the right segment colon. The discovery of the KRAS Q61 role in tumor phenotypes provides the foundation for new therapeutic strategies and perspectives on molecular subtypes classification of CRC.

Abstract

Background: Biomarker profiles should represent a coherent description of the colorectal cancer (CRC) stage and its predicted evolution. Methods: Using droplet digital PCR, we detected the allelic frequencies (AF) of KRAS, NRAS, BRAF, and EGFR mutations from 60 tumors. We employed a pair-wise association approach to estimate the risk involving AF mutations as outcome variables for clinical data and as predicting variables for tumor-staging. We evaluated correlations between mutations of AFs and also between the mutations and histopathology features (tumor staging, inflammation, differentiation, and invasiveness). Results: KRAS G12/G13 mutations were present in all patients. KRAS Q61 was significantly associated with poor differentiation, high desmoplastic reaction, invasiveness (ypT4), and metastasis (ypM1). NRAS and BRAF were associated with the right-side localization of tumors. Diabetic patients had a higher risk to exhibit NRAS G12/G13 mutations. BRAF and NRAS G12/G13 mutations co-existed in tumors with invasiveness limited to the submucosa. Conclusions: The associations we found and the mutational AF we reported may help to understand disease processes and may be considered as potential CCR biomarker candidates. In addition, we propose representative mutation panels associated with specific clinical and histopathological features of CRC, as a unique opportunity to refine the degree of personalization of CRC treatment.