K-Ras mutations and treatment outcome in colorectal cancer patients receiving exclusive fluoropyrimidine therapy

Precision Oncology in Gastrointestinal and Colorectal Cancer Surgery

Precision medicine is used to treat gastrointestinal malignancies including esophageal, gastric, small bowel, colorectal, and pancreatic cancers. Cutting-edge assays to detect and treat these cancers are active areas of research and will soon become standard of care. Colorectal cancer is a prime example of precision oncology as disease site is no longer the final determinate of treatment. Here, the authors describe how leveraging an understanding of tumor biology translates to individualized patient care using evidence-based practices.

A cautionary tale: an evaluation of the performance of treatment switching adjustment methods in a real world case study

BACKGROUND

Treatment switching in randomised controlled trials (RCTs) is a problem for health technology assessment when substantial proportions of patients switch onto effective treatments that would not be available in standard clinical practice. Often statistical methods are used to adjust for switching: these can be applied in different ways, and performance has been assessed in simulation studies, but not in real-world case studies. We assessed the performance of adjustment methods described in National Institute for Health and Care Excellence Decision Support Unit Technical Support Document 16, applying them to an RCT comparing panitumumab to best supportive care (BSC) in colorectal cancer, in which 76% of patients randomised to BSC switched onto panitumumab. The RCT resulted in intention-to-treat hazard ratios (HR) for overall survival (OS) of 1.00 (95% confidence interval [CI] 0.82-1.22) for all patients, and 0.99 (95% CI 0.75-1.29) for patients with wild-type KRAS (Kirsten rat sarcoma virus).

METHODS

We tested several applications of inverse probability of censoring weights (IPCW), rank preserving structural failure time models (RPSFTM) and simple and complex two-stage estimation (TSE) to estimate treatment effects that would have been observed if BSC patients had not switched onto panitumumab. To assess the performance of these analyses we ascertained the true effectiveness of panitumumab based on: (i) subsequent RCTs of panitumumab that disallowed treatment switching; (ii) studies of cetuximab that disallowed treatment switching, (iii) analyses demonstrating that only patients with wild-type KRAS benefit from panitumumab. These sources suggest the true OS HR for panitumumab is 0.76-0.77 (95% CI 0.60-0.98) for all patients, and 0.55-0.73 (95% CI 0.41-0.93) for patients with wild-type KRAS.

RESULTS

Some applications of IPCW and TSE provided treatment effect estimates that closely matched the point-estimates and CIs of the expected truths. However, other applications produced estimates towards the boundaries of the expected truths, with some TSE applications producing estimates that lay outside the expected true confidence intervals. The RPSFTM performed relatively poorly, with all applications providing treatment effect estimates close to 1, often with extremely wide confidence intervals.

CONCLUSIONS

Adjustment analyses may provide unreliable results. How each method is applied must be scrutinised to assess reliability.

Investigating genomic, proteomic, and post-transcriptional regulation profiles in colorectal cancer: a comparative study between primary tumors and associated metastases

INTRODUCTION

Approximately 50% of patients with primary colorectal carcinoma develop liver metastases. This study investigates the possible molecular discrepancies between primary colorectal cancer (pCRC) and their respective metastases.

METHODS

A total of 22 pairs of pCRC and metastases were tested. Mutation profiling of 26 cancer-associated genes was undertaken in 22/22primary-metastasis tumour pairs using next-generation sequencing, whilst the expression of a panel of six microRNAs (miRNAs) was investigated using qPCRin 21/22 pairs and 22 protein biomarkers was tested using Reverse Phase Protein Array (RPPA)in 20/22 patients' tumour pairs.

RESULTS

Among the primary and metastatic tumours the mutation rates for the individual genes are as follows:TP53 (86%), APC (44%), KRAS (36%), PIK3CA (9%), SMAD4 (9%), NRAS (9%) and 4% for FBXW7, BRAF, GNAS and CDH1. The primary-metastasis tumour mutation status was identical in 54/60 (90%) loci. However, there was discordance in heterogeneity status in 40/58 genetic loci (z-score = 6.246, difference = 0.3793, P < 0.0001). Furthermore, there was loss of concordance in miRNA expression status between primary and metastatic tumours, and 57.14-80.95% of the primary-metastases tumour pairs showed altered primary-metastasis relative expression in all the miRNAs tested. Moreover, 16 of 20 (80%) tumour pairs showed alteration in at least 3 of 6 (50%) of the protein biomarker pathways analysed.

CONCLUSION

The molecular alterations of primary colorectal tumours differ significantly from those of their matched metastases. These differences have profound implications for patients' prognoses and response to therapy.

Colorectal Cancer Liver Metastases: Genomics and Biomarkers with Focus on Local Therapies

Molecular cancer biomarkers help personalize treatment, predict oncologic outcomes, and identify patients who can benefit from specific targeted therapies. Colorectal cancer (CRC) is the third-most common cancer, with the liver being the most frequent visceral metastatic site. KRAS, NRAS, BRAF V600E Mutations, DNA Mismatch Repair Deficiency/Microsatellite Instability Status, HER2 Amplification, and NTRK Fusions are NCCN approved and actionable molecular biomarkers for colorectal cancer. Additional biomarkers are also described and can be helpful in different image-guided hepatic directed therapies specifically for CRLM. For example, tumors maintaining the Ki-67 proliferation marker after thermal ablation was shown to be particularly resilient to ablation. Ablation margin was also shown to be an important factor in predicting local recurrence, with a ≥10 mm minimal ablation margin being required to attain local tumor control, especially for patients with mutant KRAS CRLM.

The role of KRAS and NRAS mutation detection in determining the therapy strategy for colorectal cancer

Colorectal cancer is one of the most frequently diagnosed malignant tumors in men and women, which is a highly heterogeneous group of neoplasms consisting of subclasses with different molecular and clinical characteristics, and, as a consequence, patients with different types of tumors require different treatment protocols. Among the predictive factors of treatment response in patients with metastatic colorectal cancer, the most studied are the genes of the RAS family (KRAS, NRAS). Determination of RAS status is the first step in individual selection of drug therapy in patients with metastatic colorectal cancer. Patients with certain mutations in KRAS and NRAS genes are resistant to anti-EGFR therapy and have a lower median survival than WT (wild type) genotypes, indicating a negative prognosis in the presence of mutations.

KRAS: A Druggable Target in Colon Cancer Patients

Mutations in KRAS are among the most frequent aberrations in cancer, including colon cancer. KRAS direct targeting is daunting due to KRAS protein resistance to small molecule inhibition. Moreover, its elevated affinity to cellular guanosine triphosphate (GTP) has made the design of specific drugs challenging. Indeed, KRAS was considered ‘undruggable’. KRASG12C is the most commonly mutated variant of KRAS in non-small cell lung cancer. Currently, the achievements obtained with covalent inhibitors of this variant have given the possibility to assess the best therapeutic approach to KRAS-driven tumors. Mutation-related biochemical assets and the tissue of origin are expected to influence responses to treatment. Further attempts to obtain mutant-specific KRAS (KRASG12C) switch-II covalent inhibitors are ongoing and the results are promising. Drugs targeted to block KRAS effector pathways could be combined with direct KRAS inhibitors, immunotherapy or T cell-targeting approaches in KRAS-mutant tumors. The development of valuable combination regimens will be essential against potential mechanisms of resistance that may arise during treatment.

Association of RAS/BRAF Status and Prognosis of Metastatic Colorectal Cancer: Analysis of 1002 Consecutive Cases

BACKGROUND

This study aimed to analyze the association of RAS/BRAF status and the prognosis of patients with metastatic colorectal cancer (mCRC) based on multi-disciplinary team (MDT) treatment mode.

METHODS

The study retrospectively analyzed 1002 consecutive mCRC patients with different tumor RAS/BRAF status at Zhongshan Hospital Fudan University from April 2012 to December 2018. The association of RAS/BRAF status with clinicopathologic features and prognosis was analyzed.

RESULTS

The mutation rate was 42.3% (424/1002) for RAS and 5.0% (50/1002) for BRAF. The RAS and BRAF mutations were mutually exclusive of each other. An association of RAS/BRAF status with sex (P < 0.001), age (P = 0.021), primary tumor location (P < 0.001), pathologic type (P < 0.001), differentiation (P < 0.001), metastatic organ (P < 0.001), carcinoembryonic antigen (CEA) (P < 0.001), and cancer antigen (CA)19-9 (P < 0.001) was observed. Overall survival (OS) was better for the RAS/BRAF wild-type patients than for the RAS-mutant patients, whereas the BRAF-mutant patients had the worst OS (51.0 vs 34.9 vs 18.9 months; P < 0.001). Regardless of RAS/BRAF status, metastases resection significantly improved OS (64.0 vs. 21.3 months; P < 0.001). Among the initially unresectable patients, the RAS/BRAF wild-type patients had a better conversional resection rate (32.9% vs 19.1% vs 0; P < 0.001) and a better OS (33.8 vs 23.3 vs 13.2 months; P = 0.005) than the RAS- and BRAF-mutant patients. Similarly, among the initially resectable patients, the RAS/BRAF wild-type patients had a better OS than the RAS- or BRAF- mutant patients (not assessable vs 51.7 vs 35.4 months; P = 0.005).

CONCLUSIONS

This large-sample study showed that regardless of metastases resection or no resection, RAS and BRAF mutations were associated with a poor prognosis. Resection of metastases could bring survival benefits for patients regardless of RAS/BRAF status.

Discordance of KRAS Mutational Status between Primary Tumors and Liver Metastases in Colorectal Cancer: Impact on Long-Term Survival Following Radical Resection

Simple Summary

KRAS mutational heterogeneity between primary colorectal cancer and liver metastases may present a challenge in assessing prognostic information prior to the multimodal treatment. Aim of our study is to assess the incidence of KRAS discordance in a single-center series by comparing primary colorectal tumor specimens with the corresponding liver metastasis. Mutation analyses in all patients were performed at the same institution. Impact of discordance on overall survival and risk factors associated with discordance were analyzed. Our study showed that KRAS discordance was observed in 15.9% of patients. In patients with wild-type colorectal primary tumors, subsequent acquisition of mutation in the corresponding liver metastasis was associated with worse overall survival and was significantly more frequently found in patients with multiple liver metastases. These results suggested that, in the era of precision medicine, the possibility of KRAS discordance should be taken into account within the multidisciplinary management of patients with metastatic colorectal cancer.

Abstract

If KRAS mutation status of primary colorectal tumor is representative of corresponding colorectal liver metastases (CRLM) mutational pattern, is controversial. Several studies have reported different rates of KRAS discordance, ranging from 4 to 32%. Aim of this study is to assess the incidence of discordance and its impact on overall survival (OS) in a homogenous group of patients. KRAS mutation status was evaluated in 107 patients resected for both primary colorectal tumor and corresponding CRLM at the same institution, between 2007 and 2018. Discordance rate was 15.9%. Its incidence varied according to the time interval between the two mutation analyses (p = 0.025; Pearson correlation = 0.2) and it was significantly higher during the first 6 months from the time of primary tumor evaluation. On multivariable analysis, type of discordance (wild-type in primary tumor, mutation in CRLM) was the strongest predictor of poor OS (p < 0.001). At multivariable logistic regression analysis, the number of CRLM >3 was an independent risk factor for the risk of KRAS discordance associated with the worst prognosis (OR = 4.600; p = 0.047). Results of our study suggested that, in the era of precision medicine, possibility of KRAS discordance should be taken into account within multidisciplinary management of patients with metastatic colorectal cancer.

Is there any clinical or laboratory predictive factor for cetuximab-induced skin toxicity?

BACKGROUND: We aim to explore the predictive role of clinical and hematological parameters for cetuximab-induced skin toxicity (CI-ST) and survival outcomes in patients according to risk categories.RESEARCH DESIGN AND METHODS: The optimal cut-off values for hematological parameters were assessed by the Receiver Operating Characteristic (ROC) analysis. Patients were classified as High risk, Intermediate risk and Low risk subgroups with respect to platelet to lymphocyte ratio (PLR) and red blood cell count (RBC) values. Kaplan-Meier test was used for survival analysis, and outcomes were analyzed by Log-rank test. P-value <0.05 considered as statistically significant.RESULTS: Among hematological parameters, only PLR and RBC were statistically significant prognostic factors.Optimal cut-off value for PLR was 196.2 (82.9% sensitivity and 61.1% specificity), and 4.610x106/µL for RBC count (65.9% sensitivity and 81.1% specificity). Patients in high risk group had increased risk with an OR:69.34 (p<0.0001), and in the intermediate risk group had an OR:28.73 (p=0.002) for CI-ST. De novo metastatic patients had 9.11-fold increased risk for CI-ST compared to recurrent metastatic patients (p=0.028).CONCLUSION: Our study indicates that risk categories based on PLR and RBC can predict CI-ST and de novo metastatic patients had higher risk for CI-ST.

Colon Cancer, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Colon Cancer focuses on systemic therapy options for the treatment of metastatic colorectal cancer (mCRC), because important updates have recently been made to this section. These updates include recommendations for first-line use of checkpoint inhibitors for mCRC, that is deficient mismatch repair/microsatellite instability-high, recommendations related to the use of biosimilars, and expanded recommendations for biomarker testing. The systemic therapy recommendations now include targeted therapy options for patients with mCRC that is HER2-amplified, or BRAF V600E mutation-positive. Treatment and management of nonmetastatic or resectable/ablatable metastatic disease are discussed in the complete version of the NCCN Guidelines for Colon Cancer available at NCCN.org. Additional topics covered in the complete version include risk assessment, staging, pathology, posttreatment surveillance, and survivorship.

New advances in the clinical management of RAS and BRAF mutant colorectal cancer patients

INTRODUCTION

In colorectal carcinogenesis, genetic alterations in RAS and BRAF oncogenes play an important role for cancer initiation and/or progression and represent a key focus in the search for targeted therapies. Despite many years of research and a great amount of studies, until very recently this pathway was considered extremely hard to downregulate to obtain a significant clinical impact in colorectal cancer patients. But better times are coming with the advent of new promising drugs and combinations strategies.

AREAS COVERED

In this review, we go over the biological characteristics of the MAPK pathway in colorectal tumors, while illustrating the clinical correlation of RAS and BRAF mutations, particularly its prognostic and predictive value. We also present newly data about recent improvements in the treatment strategy for patients harboring these types of tumors.

EXPERT COMMENTARY

With great advances in the knowledge of molecular basis of RAS and BRAF mutant colorectal cancer in conjunction with biotechnology development and the constant effort for improvement, in the near future many new therapeutic options would be available for the management of this group of patient with dismal prognosis.

Genomic and epigenomic biomarkers in colorectal cancer: From diagnosis to therapy

Colorectal cancer (CRC) is the second leading cause of cancer-related deaths in the United States. Despite ongoing efforts aimed at increasing screening for CRC and early detection, and development of more effective therapeutic regimens, the overall morbidity and mortality from this malignancy remains a clinical challenge. Therefore, identifying and developing genomic and epigenomic biomarkers that can improve CRC diagnosis and help predict response to current therapies are of paramount importance for improving survival outcomes in CRC patients, sparing patients from toxicity associated with current regimens, and reducing the economic burden associated with these treatments. Although efforts to develop biomarkers over the past decades have achieved some success, the recent availability of high-throughput analytical tools, together with the use of machine learning algorithms, will likely hasten the development of more robust diagnostic biomarkers and improved guidance for clinical decision-making in the coming years. In this chapter, we provide a systematic and comprehensive overview on the current status of genomic and epigenomic biomarkers in CRC, and comment on their potential clinical significance in the management of patients with this fatal malignancy, including in the context of precision medicine.

Mismatch repair status between primary colorectal tumor and metastatic tumor, a retrospective consistent study

Objectives Mismatch repair (MMR) and Microsatellite instability (MSI) are critical when considering immunotherapy and chemotherapeutic drugs an option for patients with colorectal cancer (CRC). We investigated the consistence of MMR status as well as MSI between primary CRC and metastatic tumor to see if the expression of four MMR proteins and the status of MSI are congruent in primary tumor and metastatic tumor. With the results of the study and future more relevant studies, the sites of MMR testing may be more precise for individualized treatment.

Study design Patients with clear diagnosis of sporadic CRC and distal organ metastasis were identified from a prospectively established database. The status of MMR and MSI was evaluated by immunohistochemistry (IHC) and Polymerase Chain Reaction (PCR) respectively of synchronously obtained tissue samples.

Results Forty patients with complete clinical date were enrolled. For primary tumor, 36/40 samples were tested as MMR-proficient (pMMR) and 4 were MMR-deficient (dMMR). For metastatic samples, 30 samples were tested as pMMR while 10 samples were dMMR. Six out of forty patients were tested as inconsistent status of MMR and MSI. After statistical analysis, the expression status of MMR was not statistically significant between primary and metastatic tumors (P=0.1405, larger than 0.05).

Conclusion Based on our samples, the status of MMR between primary CRC and metastatic tumor was consistent, thus test of MMR status can be performed at both sites. However, due to the limited samples enrolled in our study, the results should be interpreted carefully.

KRAS amplification in metastatic colon cancer is associated with a history of inflammatory bowel disease and may confer resistance to anti-EGFR therapy

Mutations in RAS occur in 30-50% of metastatic colorectal carcinomas (mCRCs) and correlate with resistance to anti-EGFR therapy. Consequently, mCRC biomarker guidelines state RAS mutational testing should be performed when considering EGFR inhibitor treatment. However, a small subset of mCRCs are reported to harbor RAS amplification. In order to elucidate the clinicopathologic features and anti-EGFR treatment response associated with RAS amplification, we retrospectively reviewed a large cohort of mCRC patients that underwent targeted next-generation sequencing and copy number analysis for KRAS, NRAS, HRAS, BRAF, and PIK3CA. Molecular testing was performed on 1286 consecutive mCRC from 1271 patients as part of routine clinical care, and results were correlated with clinicopathologic findings, mismatch repair (MMR) status and follow-up. RAS amplification was detected in 22 (2%) mCRCs and included: KRAS, NRAS, and HRAS for 15, 5, and 2 cases, respectively (6-21 gene copies). Patients with a KRAS-amplified mCRC were more likely to report a history of inflammatory bowel disease (p < 0.001). In contrast, mutations in KRAS were associated with older patient age, right-sided colonic origin, low-grade differentiation, mucinous histology, and MMR proficiency (p ≤ 0.017). Four patients with a KRAS-amplified mCRC and no concomitant RAS/BRAF/PIK3CA mutations received EGFR inhibitor-based therapy, and none demonstrated a clinicoradiographic response. The therapeutic impact of RAS amplification was further evaluated using a separate, multi-institutional cohort of 23 patients. Eight of 23 patients with KRAS-amplified mCRC received anti-EGFR therapy and all 8 patients exhibited disease progression on treatment. Although the number of KRAS-amplified mCRCs is limited, our data suggest the clinicopathologic features associated with mCRC harboring a KRAS amplification are distinct from those associated with a KRAS mutation. However, both alterations seem to confer EGFR inhibitor resistance and, therefore, RAS testing to include copy number analyses may be of consideration in the treatment of mCRC.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

KRAS Status as a Predictor of Chemotherapy Activity in Patients With Metastatic Colorectal Cancer

BACKGROUND

KRAS mutations occur in 40% of colorectal cancers (CRCs), affecting the efficacy of agents targeting the epidermal growth factor receptor. However, the effect of KRAS mutation status on the activity of non-epidermal growth factor receptor-targeting chemotherapy has not been fully elucidated. The aim of the present study is to evaluate the effect of KRAS status on the activity of different chemotherapeutic regimens.

PATIENTS AND METHODS

A retrospective chart review of chemotherapy-treated patients with metastatic CRC with known KRAS status was undertaken. Chemotherapy effects were measured by progression-free survival, time to chemotherapy resistance, and overall survival. Analysis was performed for the different chemotherapy regimens, and according to the KRAS mutation status while adjusting for potential confounders.

RESULTS

KRAS mutations were detected in 43% of 223 patients with metastatic CRC who were treated at the Ottawa Hospital. The baseline distribution of KRAS wild-type (WT) and mutant status was similar. The median follow-up was 27.2 months. Regimens received included single agents or combinations of 2 or 3 chemotherapies. Among those treated with capecitabine-based regimens, survival was longer for patients with KRAS WT status (hazard ratio, 0.47; 95% confidence interval, 0.23-0.95; P < .0001) when compared with those with mutant status. The median overall survival was 46.7 versus 32.6 months for patients with KRAS WT versus mutant status, respectively. The time to chemotherapy resistance was also significantly longer for patients with WT status (hazard ratio, 0.49; 95% confidence interval, 0.25-0.97; P = .0398). A trend for progression-free survival did not reach statistical significance.

CONCLUSION

Patients with KRAS WT tumors may benefit more from capecitabine-based treatments than patients with mutant status. Further research is needed to explain this data.

Necessity of Genetic Evaluation of Metachronous Metastases of Colorectal Cancer: Quantitative Analysis of Genetic Discordance Between Metachronous Metastases and Radically Resected Primary Colorectal Cancers Using Next-Generation Sequencing

BACKGROUND

Mutation analyses provide the basis of selecting an appropriate target agent for the treatment of metastatic colorectal cancer. However, metachronous metastases developed after the treatment of primary tumor could create significant opportunities for different genetic profiles relative to the primary tumors.

OBJECTIVE

The purpose of this study was to assess the necessity of genetic evaluation of metachronous metastases; we performed a quantitative analysis of genetic discordance between metachronous metastases and radically resected primary colorectal cancers using next-generation sequencing.

DESIGN

This was a retrospective study.

SETTINGS

Patients from a single-institution tertiary care center were studied.

PATIENTS

We enrolled 33 patients who underwent resection of metachronous metastases between January 2014 and December 2016, ≥6 months after radical resection of primary colorectal cancer and whose tissue was available for analysis.

MAIN OUTCOME MEASURES

Tumor samples were analyzed by next-generation sequencing. The mutant allele frequency was analyzed to evaluate the proportion of mutations in the tumor tissue.

RESULTS

The mutant allele frequency of KRAS in metachronous metastases was higher in 6 cases (mean difference =% 25.5% (range, 9.5%-58.0%)) and lower in 3 cases (mean difference = 9.3% (range, 8.0-10.0%) compared with each of their primary tumors. In 1 case, the KRAS mutant-type (mutant allele frequency = 22.6%) metachronous metastasis had developed from the KRAS wild-type primary tumor.

LIMITATIONS

Tumor sample may not represent perfectly the whole tumor of the patient because of heterogeneity.

CONCLUSIONS

Genetic discordance can exist between metachronous metastases and radically resected primary colorectal cancers. For appropriate target therapy, genetic evaluation of metachronous metastases needs to be considered when possible. See Video Abstract at http://links.lww.com/DCR/A932.

Predictive Biomarkers in Metastatic Colorectal Cancer: A Systematic Review

PURPOSE

The development and use of predictive biomarkers to guide treatment decisions are paramount not only for improving survival in patients with metastatic colorectal cancer (mCRC), but also for sparing them from unnecessary toxicity and reducing the economic burden of expensive treatments. We conducted a systematic review of published studies and evaluated the predictive biomarker landscape in the mCRC setting from a molecular and clinical viewpoint.

METHODS

Studies analyzing predictive biomarkers for approved therapies in patients with mCRC were identified systematically using electronic databases. Preclinical studies and those providing no relevant information were excluded.

RESULTS

A total of 173 studies comprising 148 biomarkers were selected for final analysis. Of all the biomarkers analyzed, 1.4% (two of 148) were explored in a prospective manner, whereas 98.6% (146 of 148) were evaluated in retrospective studies. Of the latter group, 78.8% (115 of 146) were not tested in subsequent phases, 9.6% (14 of 146) were tested in other retrospective cohorts, 8.9% (13 of 146) were retrospectively tested in at least one or more randomized cohorts, and only 2.7% (four of 146) were prospectively tested in a clinical trial. Finally, only 1.4% (two of 148) were validated sufficiently and are recognized as biomarkers for guiding treatment decision making in patients with mCRC. These markers were RAS mutational status for anti-EGFR antibodies and microsatellite instability status for anti-programmed cell death-1 drugs.

CONCLUSION

Despite notable efforts to identify predictive biomarkers for various therapies used in the mCRC setting, because of a lack of data beyond retrospective studies and successful biomarker-driven approaches, only two molecular biomarkers have thus far found their translation into the clinic, highlighting the imperative need for implementing novel strategies and additional research in this clinically important field.

Metastatic Profile of Colorectal Cancer: Interplay Between Primary Tumor Location and KRAS Status

BACKGROUND

Mutant KRAS tumors are purported to metastasize differently than wild-type KRAS tumors. The biological heterogeneity of tumors from different parts of the colon are also reported to affect metastasis. This study aims to characterize the metastatic profile by evaluating these factors in unison.

METHODS

Retrospective analysis of 899 patients with metastatic colorectal cancers treated from January 2010 to December 2014 was conducted. KRAS mutation status and primary tumors location were correlated with single-site metastasis (liver, lung, and peritoneum) and dual-site metastases (liver-peritoneum, liver-lung, and lung-peritoneum). Patients without KRAS analyses were excluded.

RESULTS

Right-sided tumors had highest frequency of peritoneal metastasis as compared to left-sided or rectal tumors (34.7% versus 15.8% versus 8.8%, P = 0.00) regardless of KRAS status (32.6% versus 38.5%, P = 0.62). Left-sided tumors with wild-type KRAS had greater proportion of liver metastasis (78.6% versus 53.5%, P = 0.00), whereas those with mutant KRAS had greater proportion of lung metastasis (23.3% versus 8.7%, P = 0.02). Rectal tumors with wild-type KRAS tend to spread to the liver (81.4% versus 48.0%, P = 0.00) and not to the peritoneum (2.3% versus 20.0%, P = 0.01). In dual-site metastases, left-sided tumors with wild-type KRAS had more liver-peritoneal metastases (75.0% versus 29.4%, P = 0.00), whereas mutant KRAS had greater lung-liver metastases (64.7% versus 20.8%, P = 0.01). Rectal tumors had the predilection for lung-liver metastases as compared to right-sided and left-sided tumors (92.3% versus 40.0% versus 39.0%, P = 0.00) regardless of KRAS status (100% versus 75%, P = 0.12).

CONCLUSIONS

Our results may streamline surveillance programs based on primary tumor location and KRAS mutational status.

Biomarker concordance between primary colorectal cancer and its metastases

Background

The use of biomarkers to target anti-EGFR treatments for metastatic colorectal cancer (CRC) is well-established, requiring molecular analysis of primary or metastatic biopsies. We aim to review concordance between primary CRC and its metastatic sites.

Methods

A systematic review and meta-analysis of all published studies (1991–2018) reporting on biomarker concordance between primary CRC and its metastatic site(s) was undertaken according to PRISMA guidelines using several medical databases. Studies without matched samples or using peripheral blood for biomarker analysis were excluded.

Findings

61 studies including 3565 patient samples were included. Median biomarker concordance for KRAS (n = 50) was 93.7% [[67], [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], [78], [79], [80], [81], [82], [83], [84], [85], [86], [87], [88], [89], [90], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100]], NRAS (n = 11) was 100% [[90], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100]], BRAF (n = 22) was 99.4% [[80], [81], [82], [83], [84], [85], [86], [87], [88], [89], [90], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100]], and PIK3CA (n = 17) was 93% [[42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66], [67], [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], [78], [79], [80], [81], [82], [83], [84], [85], [86], [87], [88], [89], [90], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100]]. Meta-analytic pooled discordance was 8% for KRAS (95% CI = 5–10%), 8% for BRAF (95% CI = 5–10%), 7% for PIK3CA (95% CI = 2–13%), and 28% overall (95% CI = 14–44%). The liver was the most commonly biopsied metastatic site (n = 2276), followed by lung (n = 438), lymph nodes (n = 1123), and peritoneum (n = 132). Median absolute concordance in multiple biomarkers was 81% (5–95%).

Interpretation

Metastatic CRC demonstrates high concordance across multiple biomarkers, suggesting that molecular testing of either the primary or liver and lung metastasis is adequate. More research on colorectal peritoneal metastases is required.

Spatio-temporal tumor heterogeneity in metastatic CRC tumors: a mutational-based approach

It is well known that activating mutations in the KRAS and NRAS genes are associated with poor response to anti-EGFR therapies in patients with metastatic colorectal cancer (mCRC). Approximately half of the patients with wild-type (WT) KRAS colorectal carcinoma do not respond to these therapies. This could be because the treatment decision is determined by the mutational profile of the primary tumor, regardless of the presence of small tumor subclones harboring RAS mutations in lymph nodes or liver metastases. We analyzed the mutational profile of the KRAS, NRAS, BRAF and PI3KCA genes using low-density microarray technology in samples of 26 paired primary tumors, 16 lymph nodes and 34 liver metastases from 26 untreated mCRC patients (n=76 samples). The most frequent mutations found in primary tumors were KRAS (15%) and PI3KCA (15%), followed by NRAS (8%) and BRAF (4%). The distribution of the mutations in the 16 lymph node metastases analyzed was as follows: 4 (25%) in KRAS gene, 3 (19%) in NRAS gene and 1 mutation each in PI3KCA and BRAF genes (6%). As expected, the most prevalent mutation in liver metastasis was in the KRAS gene (35%), followed by PI3KCA (9%) and BRAF (6%). Of the 26 cases studied, 15 (58%) displayed an overall concordance in the mutation status detected in the lymph node metastases and liver metastases compared with primary tumor, suggesting no clonal evolution. In contrast, the mutation profiles differed in the primary tumor and lymph node/metastases samples of the remaining 11 patients (48%), suggesting a spatial and temporal clonal evolution. We confirm the presence of different mutational profiles among primary tumors, lymph node metastases and liver metastases. Our results suggest the need to perform mutational analysis in all available tumor samples of patients before deciding to commence anti-EGFR treatment.

Colorectal Liver Metastases: A Pathologist's Guide to Creating an Informative Report and Improving Patient Care

CONTEXT.—

In this era of minimally invasive procedures for diagnosis, prognosis, and treatment, pathologists are at the forefront of analyzing specimens and are expected to make more specific diagnoses, providing additional information from the material they receive.

OBJECTIVE.—

To familiarize pathologists with the essential components of surgical pathology reports for colorectal liver metastases (CRLM) resections.

DATA SOURCES.—

Colorectal cancer is the third most common cancer in the world and the liver is the most frequent site of metastases. Not all patients are candidates for surgery initially and may be treated with neoadjuvant chemotherapy, most commonly with FOLFOX (5-fluorouracil/leucovorin and oxaliplatin) and FOLFIRI (5-fluorouracil/leucovorin and irinotecan), after which they may become surgical candidates. When CRLM resections are received post neoadjuvant, the pathologist needs to not only report margin status but also report details regarding the tumor's response to treatment, and should evaluate the nonneoplastic parenchyma for chemotherapy-related injury, such as sinusoidal obstruction syndrome and/or steatohepatitis that may be caused by treatment. If ancillary tests, such as molecular studies (eg, KRAS, BRAF, NRAS, and microsatellite instability), have been previously conducted, these results should be included in the report. If not, they should be ordered for the resection specimen.

CONCLUSIONS.—

In this review, we will describe strategies and practical approaches to maximize the information gained from CRLM resections. A checklist is provided that may be used while signing out these cases to remind pathologists of additional components they may wish to include in their reports to best guide patient management.

Rare genetic heterogeneity within single tumor discovered for the first time in colorectal liver metastases after liver resection

Effective individualized treatment of patients with colorectal liver metastases (CLM) requires tumor genotyping, usually based on the analysis of one single sample per patient. Therapy failure may partially be explained by sampling errors and/or intratumoral genetic heterogeneity. We aimed to demonstrate intratumoral genetic heterogeneity in CLM and enable pathologists to select tumor tissue for genotyping. All the tumors of 86 patients who underwent liver resection for a single CLM were reviewed. Of the 86 patients, 66 patients received chemotherapy and 20 patients did not receive chemotherapy before liver resection. All the tumor areas sampled were analyzed for KRAS, BRAF, PIK3CA, and NRAS mutations. The mutational status was tested in 74 cases, 7 cases had no tumoral cells due to complete responses and 5 blocks were unavailable. Of the 59/74 CLM with > 1 sample, 56 showed the same mutational status between the samples. The remaining 3 cases (5% of all cases) showed genetic heterogeneity for KRAS in 2 and BRAF in 1 patient. Genetic heterogeneity correlated with lower rate of viable tumor cells (p=0.009) and higher rate of mucin pools (p=0.013). We demonstrate for the first time the existence of genetic intratumoral heterogeneity in 5% of CLM. In routine practice, this low incidence does not require the genotyping of additional tumor samples. The correlation between the genetic heterogeneity and some histological components of the CLM should be verified by further in situ mutation assay.

BRAF Mutation Status Concordance Between Primary Cutaneous Melanomas and Corresponding Metastases: A Review of the Latest Evidence

The identification of B-Raf proto-oncongene (BRAF) mutation and the emergence of targeted therapy marked a turning point in the treatment of melanoma. The study of mutation status concordance between primary tumors and metastases in this cancer has major treatment implications as it facilitates the selection of candidates for targeted therapy. This review analyzes the evidence on the level of mutation status concordance between primary tumors and different types of metastases in cutaneous melanoma and provides an overview of the advantages and disadvantages of the various methods used to detect BRAF mutations.

Tumor Biology Rather Than Surgical Technique Dictates Prognosis in Colorectal Cancer Liver Metastases

INTRODUCTION

The interplay of tumor biology and surgical margin status after resection for colorectal liver metastasis (CRLM) remains controversial. Consequently, we sought to determine the impact of surgical margin status on overall survival (OS) stratified by KRAS mutational status.

MATERIALS AND METHODS

Four hundred eighty-five patients with known KRAS mutational status were identified. Clinicopathologic and long-term survival data were collected and assessed.

RESULTS

On pathology, most patients (n = 380; 78.3 %) had an R0 margin, while 105 (21.7 %) had an R1. Roughly two thirds of tumors were KRAS wild type (wtKRAS) (n = 307, 63.3 %), while 36.7 % (n = 178) had KRAS mutations (mutKRAS). Median and 5-year OS of the entire cohort was 65.8 months and 53.8 %, respectively. An R1 resection was associated with worse 5-year OS compared with R0 (42.4 % vs. 57.1 %; hazard ratio (HR) 1.82, 95 % CI 1.28-2.57; P = 0.001). After controlling for KRAS status, the survival benefit associated with an R0 resection persisted only among patients with wtKRAS tumors (HR 2.16, 95 % CI 1.42-3.30; P < 0.001). In contrast, surgical margin had no impact on OS among patients with mutKRAS tumors (5-year OS R0, 40.7 % vs. R1, 46.7 %; HR 1.34, 95 % CI 0.73-2.48; P = 0.348).

CONCLUSION

The impact of margin status differed by KRAS mutation status. An R0 margin only provided a survival benefit to patients with wtKRAS tumors. Tumor biology and not surgical technique determined prognosis.

Mutation location on the RAS oncogene affects pathologic features and survival after resection of colorectal liver metastases

BACKGROUND

In the past 3 decades, a better understanding of gene mutations and their role in carcinogenesis has led to improvement in our ability to treat patients with metastatic disease. The objective of the current study was to determine whether the location of a driver mutation within an affected gene impacts the biology of metastatic colorectal cancer.

METHODS

DNA was collected from 165 randomly selected specimens of patients who underwent margin-negative resection of colorectal liver metastases with curative intent. Sequenom analysis and Sanger sequencing were used to evaluate mutations in K/NRAS, PIK3CA, BRAF, and TP53.

RESULTS

BRAF mutation was associated with early recurrence and death, whereas no impact of TP53 or PIK3CA mutation was identified. Although K/NRAS mutation was associated with worse survival in this cohort, this difference was no longer evident when those who had received anti-EGFR therapy were excluded. When stratifying patients according to the exon on which K/NRAS was mutated, there were dramatic differences in both survival and pathologic features. Exon 4 mutations were associated with large, solitary metastases occurring at long disease-free intervals compared with exon 3 mutations, which presented with small, numerous lesions. Patients who had exon 4 mutations recurred infrequently and had significantly longer survival compared with those who had wild type or other mutations.

CONCLUSIONS

By using this model of curative-intent, margin-negative resection in patients at high risk of recurrence, the authors were able to establish a link between mutation location within the K/NRAS gene and the biology of metastatic colorectal cancer. Cancer 2017;123:568-575. © 2016 American Cancer Society.

ESMO consensus guidelines for the management of patients with metastatic colorectal cancer

Colorectal cancer (CRC) is one of the most common malignancies in Western countries. Over the last 20 years, and the last decade in particular, the clinical outcome for patients with metastatic CRC (mCRC) has improved greatly due not only to an increase in the number of patients being referred for and undergoing surgical resection of their localised metastatic disease but also to a more strategic approach to the delivery of systemic therapy and an expansion in the use of ablative techniques. This reflects the increase in the number of patients that are being managed within a multidisciplinary team environment and specialist cancer centres, and the emergence over the same time period not only of improved imaging techniques but also prognostic and predictive molecular markers. Treatment decisions for patients with mCRC must be evidence-based. Thus, these ESMO consensus guidelines have been developed based on the current available evidence to provide a series of evidence-based recommendations to assist in the treatment and management of patients with mCRC in this rapidly evolving treatment setting.

Tumour heterogeneity: principles and practical consequences

Two major reasons compel us to study tumour heterogeneity: firstly, it represents the basis of acquired therapy resistance, and secondly, it may be one of the major sources of the low level of reproducibility in clinical cancer research. The present review focuses on the heterogeneity of neoplastic disease, both within the primary tumour and between primary tumour and metastases. We discuss different levels of heterogeneity and the current understanding of the phenomenon, as well as imminent developments relevant for clinical research and diagnostic pathology. It is necessary to develop new tools to study heterogeneity and new biomarkers for heterogeneity. Established and new in situ methods will be very useful. In future studies, not only clonal heterogeneity needs to be addressed but also non-clonal phenotypic heterogeneity which might be important for therapy resistance. We also review heterogeneity established in major tumour types, in order to explore potential similarities that might help to define new strategies for targeted therapy.

Codon 13 KRAS mutation predicts patterns of recurrence in patients undergoing hepatectomy for colorectal liver metastases

BACKGROUND

Investigations regarding the impact of tumor biology after surgical management of colorectal liver metastasis have focused largely on overall survival. We investigated the impact of codon-specific KRAS mutations on the rates and patterns of recurrence in patients after surgery for colorectal liver metastasis (CRLM).

METHODS

All patients who underwent curative-intent surgery for CRLM between 2002 and 2015 at Johns Hopkins who had available data on KRAS mutation status were identified. Clinico-pathologic data, recurrence patterns, and recurrence-free survival (RFS) were assessed using univariable and multivariable analyses.

RESULTS

A total of 512 patients underwent resection only (83.2%) or resection plus radiofrequency ablation (16.8%). Although 5-year overall survival was 64.6%, 284 (55.5%) patients recurred with a median RFS time of 18.1 months. The liver was the initial recurrence site for 181 patients, whereas extrahepatic recurrence was observed in 162 patients. Among patients with an extrahepatic recurrence, 102 (63%) had a lung recurrence. Although overall KRAS mutation was not associated with overall RFS (P = 0.186), it was independently associated with a worse extrahepatic (P = 0.004) and lung RFS (P = 0.007). Among patients with known KRAS codon-specific mutations, patients with codon 13 KRAS mutation had a worse 5-year extrahepatic RFS (P = 0.01), whereas codon 12 mutations were not associated with extrahepatic (P = 0.11) or lung-specific recurrence rate (P = 0.24). On multivariable analysis, only codon 13 mutation independently predicted worse overall extrahepatic RFS (P = 0.004) and lung-specific RFS (P = 0.023).

CONCLUSIONS

Among patients undergoing resection of CRLM, overall KRAS mutation was not associated with RFS. KRAS codon 13 mutations, but not codon 12 mutations, were associated with a higher risk for overall extrahepatic recurrence and lung-specific recurrence. Cancer 2016. © 2016 American Cancer Society. Cancer 2016;122:2698-2707. © 2016 American Cancer Society.

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

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

Primary Tumor Resection and Overall Survival in Patients With Metastatic Colorectal Cancer Treated With Palliative Intent

BACKGROUND

The survival impact of primary tumor resection in patients with metastatic colorectal cancer (mCRC) treated with palliative intent remains uncertain. In the absence of randomized data, the objectives of the present study were to examine the effect of primary tumor resection (PTR) and major prognostic variables on overall survival (OS) of patients with de novo mCRC.

PATIENTS AND METHODS

Consecutive patients from the Australian 'Treatment of Recurrent and Advanced Colorectal Cancer' registry were examined from June 2009 to March 2015. Univariate and multivariate Cox proportional hazards regression analyses were used to identify associations between multiple patient or clinical variables and OS. Patients with metachronous mCRC were excluded from the analyses.

RESULTS

A total of 690 patients de novo and 373 metachronous mCRC patients treated with palliative intent were identified. The median follow-up period was 30 months. The median age of de novo patients was 66 years; 57% were male; 77% had an Eastern Cooperative Oncology Group performance status of 0 to 1; and 76% had a colon primary. A total of 216 de novo mCRC patients treated with palliative intent underwent PTR at diagnosis and were more likely to have a colon primary (odds ratio [OR], 15.4), a lower carcinoembryonic antigen level (OR, 2.08), and peritoneal involvement (OR, 2.58; P < .001). On multivariate analysis, PTR at diagnosis in de novo patients was not associated with significantly improved OS (hazard ratio [HR], 0.82; 99% confidence interval [CI], 0.62-1.09; P = .068). PTR at diagnosis did not correlate with outcome in de novo patients with a colon primary (HR, 0.74; 99% CI, 0.54-1.01; P = .014) or a rectal primary (HR, 0.81; 99% CI, 0.27-2.44; P = .621).

CONCLUSION

For de novo mCRC patients treated with palliative intent, PTR at diagnosis does not significantly improve OS when adjusting for known major prognostic factors. The outcomes of randomized trials examining the survival impact of PTR are awaited.

Tumor evolution and intratumor heterogeneity in colorectal carcinoma: insights from comparative genomic profiling of primary tumors and matched metastases

Metastatic colorectal cancer (CRC) is one of the leading causes of cancer-related mortality among men and women worldwide. Over the past few decades, advances in our understanding of the genetic and epigenetic underpinnings of CRC have led to important insights into the pathogenesis of invasive tumors and have identified different molecular subgroups. Nonetheless, the events that might facilitate dissemination of tumor cells to distant sites giving rise to metastatic disease are not well characterized. Furthermore, in contrast to intertumor heterogeneity the extent of intratumor heterogeneity in different types of CRC has not been fully defined. In this paper, we review studies that have compared the genetic profile of primary invasive carcinomas to that of matched metastases and discuss the implications of their findings for our understanding of tumor evolution and for the clinical management of patients with advanced CRC.

Relationship Between 18F-FDG PET/CT Scans and KRAS Mutations in Metastatic Colorectal Cancer

Several studies have shown that KRAS mutations in colorectal cancer (CRC) result in the lack of response to anti-epidermal growth factor receptor-based therapy; thus, KRAS mutational testing has been incorporated into routine clinical practice. However, 1 limitation of this test is the heterogeneity of KRAS status, which can be either intratumoral heterogeneity within an individual primary CRC or discordant KRAS status between a primary CRC and its corresponding metastases. We previously reported that (18)F-FDG accumulation was significantly higher in primary CRCs with mutated KRAS than in those with wild-type KRAS. However, the clinical utility of the previous report has been limited because endoscopic biopsy for testing KRAS status is safe and feasible only in primary CRC. The purpose of this study was to investigate whether KRAS status is associated with (18)F-FDG accumulation in metastatic CRC and whether (18)F-FDG PET/CT scans can be used to predict the KRAS status of metastatic CRC.

METHODS

A retrospective analysis was performed on 55 metastatic CRC tumors that were identified by (18)F-FDG PET/CT before surgical resection. Maximum standardized uptake value (SUVmax) of the respective metastatic tumor was calculated from (18)F-FDG accumulation.

RESULTS

From the analysis with the 55 tumors, no significant correlation was found between SUVmax and KRAS status. We next analyzed only tumors larger than 10 mm to minimize the bias of partial-volume effect and found that SUVmax was significantly higher in the KRAS-mutated group than in the wild-type group (8.3 ± 4.1 vs. 5.7 ± 2.4, respectively; P = 0.03). Multivariate analysis indicated that SUVmax remained significantly associated with KRAS mutations (P = 0.04). KRAS status could be predicted with an accuracy of 71.4% when an SUVmax cutoff value of 6.0 was used.

CONCLUSION

(18)F-FDG accumulation into metastatic CRC was associated with KRAS status. (18)F-FDG PET/CT scans may be useful for predicting the KRAS status of metastatic CRC and help in determining the therapeutic strategies against metastatic CRC.

KRAS discordance between primary and recurrent tumors after radical resection of colorectal cancers

BACKGROUND

Although KRAS shows high concordance between primary and metastatic colorectal cancers, recent studies have reported discordance and intra-tumoral heterogeneity. To evaluate KRAS concordance between primary colorectal cancers and recurrent tumors after radical resection, we performed this study.

METHODS

Between January 2007 and August 2013, among patients underwent radical resection for primary colorectal cancers and tissue sampling of recurred tumors including resection or biopsy, 74 patients whose both primary and recurred tumor tissues were available for KRAS analysis were enrolled. The clinical and pathologic data were retrospectively revised and KRAS analyses were performed.

RESULTS

The patients with initial M1 stage showed significantly higher KRAS discordance rate (54.5%). The KRAS concordance rate was 79.7% (n = 59). Forty-two patients (56.8%) showed the wild-to-wild type and 17 (22.9%) showed the mutant-to-mutant type. The discordance rate was 20.3% (n = 15). Eight patients (10.8%) showed the wild-to-mutant type, and 7 (9.5%) showed the mutant-to-wild type. Among 15 discordance cases, intra-tumoral heterogeneity was found in 26.7% (n = 4).

CONCLUSIONS

There is 20.3% KRAS discordance between primary and recurrent tumors, which is higher rate than is generally known. For selection of the effective target agent, KRAS analysis of recurred tumors will be necessary, if it is available.

Concordant analysis of KRAS, BRAF, PIK3CA mutations, and PTEN expression between primary colorectal cancer and matched metastases

Current data on the concordance of KRAS, BRAF, PIK3CA mutation status or PTEN expression status between primary tumors and metastases in colorectal cancer (CRC) are conflicting. We conducted a systematic review and meta-analysis to examine concordance and discordance of the status of these four biomarkers between primary tumors and corresponding metastases in CRC patients. The biomarker status in primary tumors was used as the reference standard. Concordance data for KRAS, BRAF, PIK3CA and PTEN were provided by 43, 16, 9 and 7 studies, respectively. The pooled concordance rate was 92.0% (95% CI: 89.7%–93.9%) for KRAS, 96.8% (95% CI: 94.8%–98.0%) for BRAF, 93.9% (95% CI: 89.7%–96.5%) for PIK3CA and 71.7% (95% CI: 57.6%–82.5%) for PTEN. The pooled false positive and false negative rates for KRAS were 9.0% (95% CI: 6.5%–12.4%) and 11.3% (95% CI: 8.0%–15.8%), respectively. KRAS, BRAF and PIK3CA mutations are highly concordant between primary tumors and corresponding metastases in CRC, but PTEN loss is not. Nine percent of patients with wild-type KRAS in primary tumors who received anti-EGFR treatment had mutant KRAS in metastases, while 11.3% patients with mutant KRAS primary tumors had wild-type KRAS in the metastases. These 11.3% patients currently do not receive potentially beneficial anti-EGFR treatment.

Association between KRAS mutation and lung metastasis in advanced colorectal cancer

Background:

KRAS mutations have been associated with lung metastases at diagnosis of metastatic colorectal cancer (mCRC), but the impact of this mutation on subsequent development of lung metastasis is unknown. We investigated KRAS mutation as a predictor of lung metastasis development.

Methods:

We retrospectively evaluated data from patients with mCRC whose tumour was tested for KRAS mutation from 2008 to 2010. The relationships of KRAS mutational status with time-to-lung metastasis (TTLM) and overall survival (OS) were analysed.

Results:

Of the 494 patients identified, 202 (41%) had tumours with KRAS mutation. KRAS mutations were associated with a shorter TTLM (median 15.2 vs 22.4 months; hazard ratio=1.40; P=0.002) and a two-fold greater odds of developing lung metastases during the disease course in patients with liver-limited mCRC at diagnosis (72 vs 56%, P=0.007). Overall survival did not differ by KRAS status.

Conclusions:

Lung metastasis was more likely to develop during the disease course in patients whose tumour had a KRAS mutation than in those whose tumour did not have a KRAS mutation. This finding may have an impact on decision making for surgical resection of metastatic disease.

Distinct gene expression profiles of proximal and distal colorectal cancer: implications for cytotoxic and targeted therapy

Colorectal cancer (CRC) is a heterogeneous disease with genetic profiles and clinical outcomes dependent on the anatomic location of the primary tumor. How location impacts the molecular makeup of a tumor and how prognostic and predictive biomarkers differ between proximal versus distal colon cancers is not well established. We investigated the associations between tumor location, KRAS and BRAF mutation status, and the mRNA expression of proteins involved in major signaling pathways, including tumor growth (EGFR), angiogenesis (VEGFR2), DNA repair (ERCC1) and fluoropyrimidine metabolism (TS). FFPE tumor specimens from 431 advanced CRC patients were analyzed. The presence of 7 different KRAS base substitutions and the BRAF V600E mutation was determined. ERCC1, TS, EGFR and VEGFR2 mRNA expression levels were detected by RT-PCR. BRAF mutations were significantly more common in the proximal colon (p<0.001), whereas KRAS mutations occurred at similar frequencies throughout the colorectum. Rectal cancers had significantly higher ERCC1 and VEGFR2 mRNA levels compared to distal and proximal colon tumors (p=0.001), and increased TS levels compared to distal colon cancers (p=0.02). Mutant KRAS status was associated with lower ERCC1, TS, EGFR, and VEGFR2 gene expression in multivariate analysis. In a subgroup analysis, this association remained significant for all genes in the proximal colon and for VEGFR2 expression in rectal cancers. The mRNA expression patterns of predictive and prognostic biomarkers as well as associations with KRAS and BRAF mutation status depend on primary tumor location. Prospective studies are warranted to confirm these findings and determine the underlying mechanisms.

KRAS mutation testing in clinical practice

Activating mutation of KRAS plays a significant role in the pathogenesis of common human malignancies and molecular testing of KRAS mutation has emerged as an essential biomarker in the current practice of clinical oncology. The presence of KRAS mutation is generally associated with clinical aggressiveness of the cancer and reduced survival of the patient. Therapeutically, KRAS mutation testing has maximum utility in stratifying metastatic colorectal carcinoma and lung cancer patients for treatment with targeted therapy. Diagnostically, KRAS mutation testing is useful in the workup of pancreaticobiliary and thyroid cancers, particularly using cytological specimens. In the era of precision medicine, the role of KRAS mutation testing is poised to expand, likely in a setting of combinatorial therapeutic strategy and requiring additional mutation testing of its upstream and/or downstream effectors.

Pragmatic issues in biomarker evaluation for targeted therapies in cancer

Predictive biomarkers are becoming increasingly important tools in drug development and clinical research. The importance of using both guidelines for specimen acquisition and analytical methods for biomarker measurements that are standardized has become recognized widely as an important issue, which must be addressed in order to provide high-quality, validated assays. Herein, we review the major challenges in biomarker validation processes, including pre-analytical (sample-related), analytical, and post-analytical (data-related) aspects of assay development. Recommendations for improving biomarker assay development and method validation are proposed to facilitate the use of predictive biomarkers in clinical trials and the practice of oncology.

The prevalent KRAS exon 2 c.35 G>A mutation in metastatic colorectal cancer patients: A biomarker of worse prognosis and potential benefit of bevacizumab-containing intensive regimens?

Bevacizumab-containing chemotherapy differently predict increased efficacy in KRAS exon 2 mutant and wild-type metastatic colorectal cancer (MCRC) patients. Mutant compared to wild-type status did not significantly affect progression-free survival (PFS) and overall survival (OS) in patients fit for first line bevacizumab-containing FIr-B/FOx regimen, and after progression. In patients unfit for intensive regimens, mutant status significantly affected PFS, while not OS. Codon 12 KRAS mutations differentially affect GTPase function, and confer worse clinical behaviour. Prognostic relevance of the prevalent c.35 G>A KRAS mutation was retrospectively evaluated. Fit c.35 G>A mutant patients showed significantly worse OS compared to wild-type and to other mutant. After progression and in unfit patients, c.35 G>A mutation affected significantly worse PFS and OS. c.35 G>A mutant status does not significantly affect worse PFS in patients fit for first line FIr-B/FOx, and it may depend upon effectiveness of anti-VEGF-containing intensive regimen.

RAS mutations predict radiologic and pathologic response in patients treated with chemotherapy before resection of colorectal liver metastases

BACKGROUND

RAS mutations have been reported to be a potential prognostic factor in patients with colorectal liver metastases (CLM). However, the impact of RAS mutations on response to chemotherapy remains unclear. The purpose of this study was to investigate the correlation between RAS mutations and response to preoperative chemotherapy and their impact on survival in patients undergoing curative resection of CLM.

METHODS

RAS mutational status was assessed and its relation to morphologic response and pathologic response was investigated in 184 patients meeting inclusion criteria. Predictors of survival were assessed. The prognostic impact of RAS mutational status was then analyzed using two different multivariate models, including either radiologic morphologic response (model 1) or pathologic response (model 2).

RESULTS

Optimal morphologic response and major pathologic response were more common in patients with wild-type RAS (32.9 and 58.9%, respectively) than in patients with RAS mutations (10.5 and 36.8%; P = 0.006 and 0.015, respectively). Multivariate analysis confirmed that wild-type RAS was a strong predictor of optimal morphologic response [odds ratio (OR), 4.38; 95% CI 1.45-13.15] and major pathologic response (OR, 2.61; 95% CI 1.17-5.80). RAS mutations were independently correlated with both overall survival and recurrence free-survival (hazard ratios, 3.57 and 2.30, respectively, in model 1, and 3.19 and 2.09, respectively, in model 2). Subanalysis revealed that RAS mutational status clearly stratified survival in patients with inadequate response to preoperative chemotherapy.

CONCLUSIONS

RAS mutational status can be used to complement the current prognostic indicators for patients undergoing curative resection of CLM after preoperative modern chemotherapy.

Epidemiology and prognosis of synchronous and metachronous colon cancer metastases: a French population-based study

BACKGROUND

Epidemiological data on synchronous and metachronous metastatic colon cancer are scarce. We assessed epidemiological characteristics and survival in synchronous and metachronous metastatic colon cancer in a French population.

METHODS

Our study included 932 cases of metastatic colon cancer diagnosed in 1999-2010 and registered in a population-based cancer registry; 758 were synchronous colon metastases and 174 metachronous metastases from resected primary colon cancers diagnosed in 1999-2005. Univariate relative survival was calculated and a multivariate model with proportional hazard applied to net survival by interval was used.

RESULTS

Mean age at diagnosis was 71.1 years for patients with metachronous metastasis and 71.4 years for those with synchronous metastasis (p=0.818). Patients with metachronous metastasis were more likely to have R0 resection (Odds Ratio: 3.05 [1.96-4.76], p<0.001) than patients with synchronous metastasis. Five-year relative survival was 7.2% for synchronous metastasis and 17.6% for metachronous metastasis (p<0.001), but did not differ significantly for patients with R0 resection (47.3% and 61.5% respectively, p=0.120). For patients not receiving chemotherapy risk of death was significantly lower in the metachronous metastasis group (Hazard Ratio=0.44 [0.32-0.60], p<0.001).

CONCLUSIONS

On a population basis, synchronous metastasis is an independent poor prognostic factor in colon cancer. Chemotherapy and resection of all metastatic sites significantly improved the outcome in patients with synchronous metastasis.

KRAS mutational concordance between primary and metastatic colorectal adenocarcinoma

KRAS mutation analysis is commonly performed on tissue samples obtained from primary colorectal cancers (CRCs). The metastatic lesions of CRC are usually considered as qualitatively similar or even identical to the primary tumors. The aim of this study was to evaluate the spectrum and distribution of KRAS mutations in a large collection of CRCs, while also evaluating the concordance of primary and metastatic lesions among available paired specimens from the same patients. A total of 729 patients with histologically confirmed advanced CRC at the University Hospital and Local Health Unit (Sassari, Italy) were included. Clinical and pathological features were obtained from medical records and/or pathology reports. Formalin-fixed, paraffin-embedded tissue samples were used for mutation analysis. Genomic DNA was isolated using a standard protocol; the coding sequence and splice junctions of exons 2 and 3 in the KRAS gene were screened by direct automated sequencing. Overall, 219 (30%) KRAS mutations were found; 208 (30.1%) were identified in the 690 primary tumors and 11 (28.2%) in the 39 metastatic tissue samples. Among the 31 (4.3%) patients who had paired samples of primary CRC and synchronous or asynchronous metastases, 28 (90.3%) showed consistent mutation patterns between the primary tumors and metastatic lesions. In one case, an additive mutation (Q61L) was found in the metastatic tissue, while two other discrepant cases exhibited a different mutation distribution; Q61H in the primitive lesion and G13V in the metastatic lesion in one case, and a mutated primary tumor (Q61L) and wild-type metastasis in another case. The results of this study confirm that a high concordance exists between the results of KRAS mutation analysis performed in primitive and metastatic CRCs; independent subclones may be generated in a limited amount of patients.