Role of Kras status in patients with metastatic colorectal cancer receiving first-line chemotherapy plus bevacizumab: a TTD group cooperative study

The Oncology Biomarker Discovery framework reveals cetuximab and bevacizumab response patterns in metastatic colorectal cancer

Precision medicine has revolutionised cancer treatments; however, actionable biomarkers remain scarce. To address this, we develop the Oncology Biomarker Discovery (OncoBird) framework for analysing the molecular and biomarker landscape of randomised controlled clinical trials. OncoBird identifies biomarkers based on single genes or mutually exclusive genetic alterations in isolation or in the context of tumour subtypes, and finally, assesses predictive components by their treatment interactions. Here, we utilise the open-label, randomised phase III trial (FIRE-3, AIO KRK-0306) in metastatic colorectal carcinoma patients, who received either cetuximab or bevacizumab in combination with 5-fluorouracil, folinic acid and irinotecan (FOLFIRI). We systematically identify five biomarkers with predictive components, e.g., patients with tumours that carry chr20q amplifications or lack mutually exclusive ERK signalling mutations benefited from cetuximab compared to bevacizumab. In summary, OncoBird characterises the molecular landscape and outlines actionable biomarkers, which generalises to any molecularly characterised randomised controlled trial.

Sintilimab plus bevacizumab, oxaliplatin and capecitabine as first-line therapy in RAS-mutant, microsatellite stable, unresectable metastatic colorectal cancer: an open-label, single-arm, phase II trial

BACKGROUND

Microsatellite stable (MSS) and RAS-mutant metastatic colorectal cancer (mCRC) patients are characterized by an immunosuppressive microenvironment and a low response rate to immunotherapy. Chemotherapy and anti-angiogenesis therapy have been reported to potentially promote immunotherapy response. This study aims to assess the preliminary anti-tumor activity and safety of sintilimab plus bevacizumab, oxaliplatin and capecitabine as a treatment option for patients with RAS-mutant MSS mCRC.

METHODS

This study was an open-label, single-arm, phase II trial in China. Patients with unresectable, RAS-mutant and MSS metastatic colorectal adenocarcinoma received treatment by intravenous sintilimab (200 mg, day 1) plus bevacizumab (7.5 mg/kg, day 1), oxaliplatin (135 mg/m2, day 1) and oral capecitabine (1 g/m2, day 1-14) in each 21-day cycle. The primary endpoints included objective response rate (ORR) and adverse events. Biomarker analysis was performed to identify potential predictors of good response to treatment. This study is registered with ClinicalTrials.gov, number NCT04194359.

FINDINGS

Between April 2021 and December 2021, 25 patients were enrolled. Two (8%) patients showed complete response (CR), 19 (76%) had partial response (PR) and 4 (16%) presented with stable disease. ORR reached 84% (95% CI, 63.9-95.5) and the disease control rate was 100% (95% CI, 86.3-100). The median progression-free survival (PFS) was 18.2 months for the full analysis set. The most common treatment-related adverse events (TRAEs) in all grades were anemia (21/25, 84%), neutropenia (20/25, 80%), and hand-foot syndrome (14/25, 56%). The most frequent grade 3 or 4 TRAEs were neutropenia (3/25, 12%) and increased alanine transaminase (2/25, 8%). No grade 5 adverse events occurred. In the exploration of biomarkers, 5 patients could be characterized as TTN/OBSCN "double-hit" after treatment, and the copy number variants burden was significantly decreased in tumor tissues after treatment compared with the baseline. Nanostring panel RNA sequencing analysis indicated a better tumor immune microenvironment cell infiltration in CR/PR patients compared with non-CR/PR patients as well as the PFS-long (≥12.5 months) group compared with the PFS-short group.

INTERPRETATION

Combination treatment with sintilimab plus bevacizumab, oxaliplatin and capecitabine as first-line treatment demonstrated a promising antitumor activity and a manageable safety profile in RAS-mutant, MSS and unresectable mCRC. Exploratory biomarker assessment analysis showed that some RAS-mutant and MSS patients changed into "immune-hot" subtype after the treatment.

FUNDING

This study was supported by the Key R&D Program of Zhejiang Province (2021C03125 to Ying Yuan), the National Natural Science Foundation of China (81872481 to Ying Yuan, 82072624 to Kefeng Ding), the Fundamental Research Funds for the Central Universities (No. 226-2022-00009 to Kefeng Ding), and the Zhejiang Provincial Natural Science Foundation of China (No. LY22H160024 to Hanguang Hu).

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

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

Pathological Features and Prognostication in Colorectal Cancer

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

Imaging features associated with survival outcomes among colorectal cancer patients with and without KRAS mutation

Background

Mutations in Kirsten rat sarcoma proto-oncogene (KRAS) have been shown to be associated with advanced-stage colorectal cancer (CRC), negative disease outcomes, and poor response to treatment. The purpose of this study was to investigate which CT features are biomarkers for KRAS gene mutation and impact the survival outcomes of colorectal cancer patients.

Results

Of the 113 CRC patients included in the study, 46 had KRAS mutations (40.71%) and 67 had no mutations (59.29%). Regional lymph node necrosis was the only imaging feature significantly associated with KRAS mutation (P = 0.011). Higher T staging and liver, lung, and distant metastasis were prognostic factors for CRC (P = 0.014, P < 0.001, P = 0.022, P < 0.001, respectively). There were no significant differences in overall survival between patients with KRAS mutations and those without (P = 0.159). However, in patients with no KRAS mutation, those with CRC on the left side had a significantly higher rate of survival than those with CRC on the right (P = 0.005).

Conclusion

Regional lymph node necrosis may be an imaging biomarker of CRC with KRAS mutation, possibly indicating poor prognosis.

An evaluation of RAS testing among metastatic colorectal cancer patients in the USA

Background: Data on RAS testing practices prior to metastatic colorectal cancer (mCRC) treatment initiation are lacking in the USA. Materials & methods: Flatiron data were utilized for patients diagnosed with mCRC between 2011 and 2017. Flatiron is a longitudinal, demographically and geographically diverse database representing data from over 1.5 million active US patients treated at 255 community and hospital-affiliated oncology clinics. Results: Among 17,387 mCRC patients 69% were RAS tested and 31% were never tested. Timing of RAS testing was as follows: 23% were tested at the time of their initial CRC diagnosis, 60% following mCRC diagnosis but prior to first line of treatment, 3% prior to third line, the remaining 14% were tested following third line. Conclusion: A third (31%) of patients failed to receive RAS testing, therefore all treatment options were unavailable to them. These data highlight how universal testing has not been achieved.

A Systematic Literature Review and Meta-Analysis Describing the Prevalence of KRAS, NRAS, and BRAF Gene Mutations in Metastatic Colorectal Cancer

Background

Tumors of the metastatic colorectal cancer (mCRC) patients that are wildtype (WT) for KRAS or NRAS mutations respond more favorably to anti-epidermal growth factor receptor (EGFR) treatments. Treatment guidelines now recommend that all mCRC patients have WT KRAS and NRAS tumor status confirmed prior to initiating anti-EGFR therapy. Evidence also suggests that BRAF mutations may predict lack of response to anti-EGFR therapy. As such, there is now a need for comprehensive data on the prevalence of KRAS, NRAS, and BRAF mutations among patients with mCRC.

Methods

A systematic literature review was conducted among studies that described the prevalence of KRAS, NRAS, and BRAF gene mutations in mCRC patients. Observational cohort studies and standard of care arm of randomized clinical trials were included. Random effects meta-analysis models were used to create summary prevalence estimates for each of the mutation types. Subgroup analyses were also conducted to identify potential sources of heterogeneity. Exploratory analyses of overall and progression-free survival by mutation status were also conducted.

Results

This systematic review and meta-analysis included 275 studies comprising 77,104 mCRC patients. The summary prevalence estimate was 35.9% for KRAS mutations, 7.1% for BRAF mutations, and 4.1% for NRAS mutations. Female patients had significantly more KRAS and BRAF mutations than males, and significant variation by study location was observed for both KRAS and BRAF mutation prevalence. Overall survival was significantly decreased for patients with KRAS, BRAF, and NRAS mutations compared to those with WT tumors. Progression-free survival was also significantly decreased among patients with KRAS and BRAF mutations.

Conclusions

KRAS, NRAS, and BRAF mutation statuses in patients with mCRC are important predictors of treatment success and may also have prognostic value. In this paper we present the first systematic and comprehensive literature review and meta-analysis of the prevalence of KRAS, BRAF, and NRAS mutations and demonstrate the prognostic impact of mutation status on survival.

Prognostic impact of K-RAS mutational status and primary tumor location in patients undergoing resection for colorectal cancer liver metastases: an update

Aim: To determine the impact of KRAS mutation status on survival in patients undergoing surgery for colorectal liver metastases (CLM). Patients & methods: Patients with resected CLM and KRAS mutations. Survival was compared between mt-KRAS and wt-KRAS. Results: Of 662 patients, 174 (26.3%) were mt-KRAS and 488 (73.7%) wt-KRAS. mt-KRAS patients had significantly lower recurrence-free survival (HR: 1.42; 95% CI: 1.10-1.84). There were no differences between the groups for sidedness. Poorer survival was associated with mt-KRAS with positive lymph nodes, >1 metastases, tumors >5 cm, synchronous tumors and R1-R2. Conclusion: KRAS mutation status can help predict recurrence-free survival. Primary tumor location was not a prognostic factor after resection. KRAS mutation status can help design a multidisciplinary approach after curative resection of CLM.

Baseline serum lactate dehydrogenase level predicts survival benefit in patients with metastatic colorectal cancer receiving bevacizumab as first-line chemotherapy: a systematic review and meta-analysis of 7 studies and 1,219 patients

Background

Bevacizumab, a humanized monoclonal antibody against vascular epithelial growth factor, plays a significant role in first-line, second-line, beyond-progression, and maintenance treatment of patients with metastatic colorectal carcinoma (mCRC). Nevertheless, there are currently no biomarkers available to predict patient response or resistance to bevacizumab, which would be useful in clinical trials.

Methods

Using PRISMA guidelines, we conducted a systematic review and meta-analysis of the association between serum lactate dehydrogenase (LDH) level and progression-free survival (PFS), overall survival (OS), and objective response rate in mCRC patients treated with bevacizumab-based first-line chemotherapy. A comprehensive, computerized literature search of PubMed, the Web of Science, Scopus, Ovid, and the gray literature was performed. Only studies conforming to specific eligibility criteria were included. Pooled hazard ratios (HRs) were estimated using random-effects or fixed-effects models according to heterogeneity between studies. Sensitivity analysis was conducted to evaluate the stability of the results by removing each individual study from the meta-analysis.

Results

Seven eligible studies of 1,219 total patients were included in the analysis. Meta-analysis of all studies revealed that high serum LDH level is associated with shorter PFS (HR: 1.43, 95% CI: 1.05-1.94; P=0.023) and OS (HR: 1.667, 95% CI: 1.230-2.259; P=0.001) times in mCRC patients treated with bevacizumab-based first-line chemotherapy. However, there was no significant association between serum LDH and objective response rate.

Conclusions

High serum LDH level is significantly associated with shorter PFS and OS time and may have utility as a prognostic factor for mCRC patients receiving bevacizumab as first-line chemotherapy and as a predictive factor for those receiving bevacizumab-based therapy at other times.

KRAS, NRAS and BRAF mutations detected by next generation sequencing, and differential clinical outcome in metastatic colorectal cancer (MCRC) patients treated with first line FIr-B/FOx adding bevacizumab (BEV) to triplet chemotherapy

BACKGROUND

First line triplet chemotherapy/BEV significantly improved clinical outcome of MCRC. KRAS/NRAS/BRAF mutations were evaluated by next generation sequencing (NGS) in MCRC patients treated with first line FIr-B/FOx.

METHODS

KRAS exons 2-4 (KRAS2-4 ), NRAS2-4 , BRAF15 were evaluated in 67 tumours by ION Torrent platform. Mutation detection criteria: >500×sequence coverage (cov); >1% mutant allelic fraction (AF). Clinical outcomes were compared by log-rank.

RESULTS

In 63 samples, KRAS2-4 /NRAS2-4 /BRAF15 wild-type (wt) were 14 (22.2%), mutant (mut) 49 (77.8%): KRAS2-4 42 (66.7%); NRAS2-4 11 (16.4%); BRAF15 5 (7.5%). Sixty mutations were detected, range 1-3 mut: 43 (71.7%) >1000×cov/>5% AF; 9 (15%) >500×cov/>5% AF; 8 (13.3%) >1000×cov/<5% AF. Mut distribution in KRAS2-4 /NRAS2-4 /BRAF15 : 40 (63.5%) >1000×cov/>5% AF, 8 (12.7%) >500×cov/>5% AF, 1 (1.6%) >1000×cov/<5% AF; BRAF15 1 (1.5%) >500×cov/>5% AF, 4 (6%) >1000×cov/<5% AF. Prevalence of ≥2 mut samples: KRAS2-4 /NRAS2-4 /BRAF15 8 (12.7%); KRAS2-4 7 (11.1%); NRAS2-4 5 (7.5%). BRAF15 mutant were all ≥2 mut (7.5%), atypical and associated to KRAS and/or NRAS mut: c.1405 G>A; c.1406 G>C; c.1756 G>A, 2 samples; c.1796 C>T. At 21 months (m) follow-up, clinical outcome wt compared to mut was not significantly different: in KRAS2-4 /NRAS2-4 /BRAF15 , progression-free survival (PFS) 18/12 m, overall survival (OS) 28/22 m; 1/≥2 mutations, PFS 14/11, OS 37/22. PFS was trendy worse in RAS/BRAF wt vs ≥2 mut genes (P 0.059).

CONCLUSIONS

Most MCRC harboured KRAS2-4 /NRAS2-4 /BRAF15 mutations by NGS, often multiple and affecting few tumoral clones; 22% were triple wt. Clinical outcome is not significantly affected by KRAS2-4 /NRAS2-4 /BRAF15 genotype, trendy different in triple wt, compared with KRAS2-4 /NRAS2-4 /BRAF15 ≥2 mut.

Retrospective study of RAS/PIK3CA/BRAF tumor mutations as predictors of response to first-line chemotherapy with bevacizumab in metastatic colorectal cancer patients

Background

After analysis of minor RAS mutations (KRAS exon 3, 4/NRAS) in the FIRE-3 and PRIME studies, an expanded range of RAS mutations were established as a negative predictive marker for the efficacy of anti-EGFR antibody treatment. BRAF and PIK3CA mutations may be candidate biomarkers for anti-EGFR targeted therapies. However, it remains unknown whether RAS/PIK3CA/BRAF tumor mutations can predict the efficacy of bevacizumab in metastatic colorectal cancer. We assessed whether selection according to RAS/PIK3CA/BRAF mutational status could be beneficial for patients treated with bevacizumab as first-line treatment for metastatic colorectal cancer.

Methods

Of the 1001 consecutive colorectal cancer patients examined for RAS, PIK3CA, and BRAF tumor mutations using a multiplex kit (Luminex®), we studied 90 patients who received combination chemotherapy with bevacizumab as first-line treatment for metastatic colorectal cancer. The objective response rate (ORR) and progression-free survival (PFS) were evaluated according to mutational status.

Results

The ORR was higher among patients with wild-type tumors (64.3%) compared to those with tumors that were only wild type with respect to KRAS exon 2 (54.8%), and the differences in ORR between patients with wild-type and mutant-type tumors were greater when considering only KRAS exon 2 mutations (6.8%) rather than RAS/PIK3CA/BRAF mutations (18.4%). There were no statistically significant differences in ORR or PFS between all wild-type tumors and tumors carrying any of the mutations. Multivariate analysis revealed that liver metastasis and RAS and BRAF mutations were independent negative factors for disease progression after first-line treatment with bevacizumab.

Conclusions

Patient selection according to RAS/PIK3CA/BRAF mutations could help select patients who will achieve a better response to bevacizumab treatment. We found no clinical benefit of restricting combination therapy with bevacizumab for metastatic colorectal cancer patients with EGFR-wild type tumors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2994-6) contains supplementary material, which is available to authorized users.

Relevance of CEA and LDH in relation to KRAS status in patients with unresectable colorectal liver metastases

BACKGROUND

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.

METHODS

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.

RESULTS

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), LDH >200 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 CEA >200 ng/mL (HR 2.1, P = 0.051), LDH >200 U/L (HR 3.8, P < 0.05), and right-sided tumors (HR 2.8, P < 0.05) had lower OS.

CONCLUSIONS

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.

Gene heterogeneity in metastasis of colorectal cancer to the lung

Colorectal cancer (CRC) as a heterogeneous disease, is one of the most common and serious cancers with high metastases and mortality. Lung is one of the most common sites of CRC metastases with high heterogeneity between cells, pathways, or molecules. The present review will focus on potential roles of gene heterogeneity in KRAS pathway in the development of CRC metastasis to lung and clinical therapies, which would lead to better understanding of the metastatic control and benefit to the treatment of metastases. KRAS is the central relay for pathways originating at the epidermal growth factor receptor (EGFR) family. KRAS mutation exists in about 40% CRC, associated with higher cumulative incidence of CRC lung metastasis, and acts as an independent predictor of metastasis to lung. Mutations in KRAS can lead to poor response of patients to panitumumab, and inferior progression-free survival. However, most patients with KRAS wild-type tumors still do not respond, which indicates other mutations. Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutation was associated with lung metastases in metastatic colorectal cancer. PIK3CA mutation in exon 20 was found to be correlated with patient survival in the metastatic setting after the treatment with cetuximab and chemotherapy. The heterogeneity of KRAS pathway was found in the phosphatase and tensin homologue deleted on chromosome ten loss, disheveled binding antagonist of beta catenin 2 overexpression and increased dual-specificity protein phosphatase 4 expression of CRC lung metastasis.

Significance of KRAS, NRAS, BRAF and PIK3CA mutations in metastatic colorectal cancer patients receiving Bevacizumab: a single institution experience

Background. KRAS mutation is an important predictive and prognostic factor for patients receiving anti-EGFR therapy. An expanded KRAS, NRAS, BRAF, PIK3CA mutation analysis provides additional prognostic information, but its role in predicting bevacizumab efficacy is unclear. The aim of our study was to evaluate the incidence of KRAS, NRAS, BRAF and PIK3CA mutations in metastatic colorectal cancer patients receiving first line oxaliplatin based chemotherapy with or without bevacizumab and to evaluate their prognostic and predictive significance.

Methods. 55 patients with the first-time diagnosed CRC receiving FOLFOX ± bevacizumab were involved in the study. Tumour blocks were tested for KRAS mutations in exons 2, 3 and 4, NRAS mutations in exons 2, 3 and 4, BRAF mutation in exon 15 and PIK3CA mutations in exons 9 and 20. The association between mutations and clinico-pathological factors, treatment outcomes and survival was analyzed.

Results. KRAS mutations were detected in 67.3% of the patients, BRAF in 1.8%, PIK3CA in 5.5% and there were no NRAS mutations. A significant association between the high CA 19–9 level and KRAS mutation was detected (mean CA 19–9 levels were 276 and 87 kIU/l, respectively, p = 0.019). There was a significantly higher response rate in the KRAS, NRAS, BRAF and PIK3CA wild type cohort receiving bevacizumab compared to any gene mutant type (100 and 60%, respectively, p = 0.030). The univariate Cox regression analysis did not confirm KRAS and other tested mutations as prognostic factors for PFS or OS.

Conclusions. Our study revealed higher KRAS and lower NRAS, BRAF and PIK3CA mutation rates in the Lithuanian population than those reported in the literature. KRAS mutation was associated with the high CA 19–9 level and mucinous histology type, but did not show any predictive or prognostic significance. The expanded KRAS, NRAS, BRAF and PIK3CA mutation analysis provided additional significant predictive information.

Updated long-term survival for patients with metastatic colorectal cancer treated with liver resection followed by hepatic arterial infusion and systemic chemotherapy

BACKGROUND AND OBJECTIVES

Patients who undergo liver resection for metastatic colorectal cancer (mCRC) have reported 5-year survivals ranging from 25% to 50%. The current study updated long-term survival for patients with resected liver metastases treated with adjuvant hepatic arterial infusion (HAI) and systemic (SYS) chemotherapy.

METHODS

Updated survival and recurrence free survival for patients treated on four consecutive adjuvant protocols with HAI and SYS from 1991 to 2009. Patients were divided into two groups: those treated on protocols before 2003 and after 2003. Median follow-up for all patients was 11 years.

RESULTS

All 287 patients enrolled in four prospective protocols after liver resection are included. Patients treated before 2003 had a median follow-up of 15 years, 5 and 10-year survivals of 56% [95%CI: 49-64%] and 40% [95%CI: 32-47%], respectively, and median survival of 71 months. Patients treated after 2003 had a median follow-up of 9 years, 5 and 10-year survivals of 78% [95%CI: 70-84%] and 61% [95%CI: 51-70%], respectively, and median survival has not been reached.

CONCLUSIONS

Survival is improving for patients with mCRC who undergo liver resection. These data support the durability of long-term survival in patients who undergo resection followed by adjuvant HAI and SYS therapy. J. Surg. Oncol. 2016;113:477-484. © 2016 Wiley Periodicals, Inc.

G12V and G12A KRAS mutations are associated with poor outcome in patients with metastatic colorectal cancer treated with bevacizumab

The v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are found in 35-45 % of colorectal cancer (CRC) cases. Although the association between the RAS signaling and angiogenesis is well known, the negative predictive value of KRAS mutation has not been established in patients treated with bevacizumab. The aim of this study was to evaluate the association between specific KRAS mutation types and outcome of patients with metastatic CRC treated with bevacizumab. The study included 404 patients with metastatic CRC (mCRC) treated with bevacizumab. Clinical data obtained from the clinical registry CORECT were retrospectively analyzed. The shortest survival was observed in patients with tumors harboring G12V or G12A KRAS mutation (G12V/A). The median progression-free survival (PFS) and overall survival (OS) for patients with tumors harboring G12V/A KRAS mutation was 6.6 and 16.8 compared to 11.6 and 26.3 months for patients with tumors harboring other KRAS mutation type (p < 0.001 and p < 0.001), while the survival of patients harboring other KRAS mutation types was comparable to those with tumors harboring wild-type KRAS gene. In the Cox multivariable analysis, KRAS G12V/A mutation type remains a significant factor predicting both PFS (HR = 2.18, p < 0.001) and OS (HR = 2.58, p < 0.001). In conclusion, the results of the present study indicate that there is a significant difference in biological behavior between tumors harboring G12V/A and other KRAS mutations. Moreover, comparison of the survival of patients with tumors harboring G12V/A KRAS mutations with those harboring wild-type KRAS gene revealed that G12V/A KRAS mutations are prognostic biomarker for inferior PFS and OS in patients with mCRC treated with bevacizumab in univariate as well as multivariable analyses.

Colorectal Cancer Classification and Cell Heterogeneity: A Systems Oncology Approach

Colorectal cancer is a heterogeneous disease that manifests through diverse clinical scenarios. During many years, our knowledge about the variability of colorectal tumors was limited to the histopathological analysis from which generic classifications associated with different clinical expectations are derived. However, currently we are beginning to understand that under the intense pathological and clinical variability of these tumors there underlies strong genetic and biological heterogeneity. Thus, with the increasing available information of inter-tumor and intra-tumor heterogeneity, the classical pathological approach is being displaced in favor of novel molecular classifications. In the present article, we summarize the most relevant proposals of molecular classifications obtained from the analysis of colorectal tumors using powerful high throughput techniques and devices. We also discuss the role that cancer systems biology may play in the integration and interpretation of the high amount of data generated and the challenges to be addressed in the future development of precision oncology. In addition, we review the current state of implementation of these novel tools in the pathological laboratory and in clinical practice.

Efficacy of bevacizumab and chemotherapy in the first-line treatment of metastatic colorectal cancer: broadening KRAS-focused clinical view

Background

The aim of the present retrospective study was to analyze clinical outcome and risk factors associated with treatment outcomes according to KRAS status in patient with metastatic colorectal cancer (mCRC) treated with bevacizumab (bev) plus chemotherapy in the first-line setting.

Methods

We performed observational study on 1622 patients with mCRC treated with bev plus oxaliplatin- or irinotecan-based chemotherapy, and correlated treatment outcomes with KRAS mutation status. The primary endpoint was progression-free survival (PFS) and additionally overall survival (OS). Adverse events of bevacizumab and risk factors including location of metastases were evaluated.

Results

Mutation in KRAS was present in 40.6% of mCRC cases. The median PFS in patients with wild-type KRAS (wtKRAS) vs mutant KRAS was 11.5 vs 11.4 months, respectively. The median OS was 30.7 vs 28.4 months (p = 0.312). Patients with KRAS mutation had lung metastases more frequently than wtKRAS individuals (32.0% vs 23.8%; p = 0.001). We observed no difference in clinical outcome between hepatic and extrahepatic metastatic disease.

Conclusion

KRAS mutation does not interfere with clinical benefit from first-line treatment with bevacizumab plus chemotherapy in mCRC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-015-0266-6) contains supplementary material, which is available to authorized users.

Targeted therapies in metastatic colorectal cancer: a systematic review and assessment of currently available data

BACKGROUND

Survival of patients with metastatic colorectal cancer (mCRC) has been significantly improved with the introduction of the monoclonal antibodies targeting the vascular endothelial growth factor (VEGF) and the epidermal growth factor receptor (EGFR). Novel molecular-targeted agents such as aflibercept and regorafenib have recently been approved. The aim of this review is to summarize and assess the effects of molecular agents in mCRC based on the available phase II and III trials, pooled analyses, and meta-analyses/systematic reviews.

METHODS

A systematic literature search was conducted using the meta-database of the German Institute of Medical Documentation and Information. Criteria of the Scottish Intercollegiate Guidelines Network were used to assess the quality of the controlled trials and systematic reviews/meta-analyses.

RESULTS

Of the 806 retrieved records, 40 publications were included. For bevacizumab, efficacy in combination with fluoropyrimidine-based chemotherapy in first- and subsequent-line settings has been shown. The benefit of continued VEGF targeting has also been demonstrated with aflibercept and regorafenib. Cetuximab is effective with fluoropyrimidine, leucovorin, and irinotecan (FOLFIRI) in first-line settings and as a single agent in last-line settings. Efficacy for panitumumab has been shown with oxaliplatin with fluoropyrimidine in first-line settings, with FOLFIRI in second-line settings, and as monotherapy in last-line settings. Treatment of anti-EGFR antibodies is restricted to patients with tumors that do not harbor mutations in Kirsten rat sarcoma and in neuroblastoma RAS.

CONCLUSION

Among various therapeutic options, the future challenge will be a better selection of the population that will benefit the most from specific anti-VEGF or anti- EGFR treatment and a careful consideration of therapy sequence.

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.

KRAS mutation influences recurrence patterns in patients undergoing hepatic resection of colorectal metastases

BACKGROUND

The validity of the KRAS mutation as a predictor of recurrence-free survival (RFS) or overall survival (OS) is unclear. The current study investigated whether the presence of the KRAS mutation decreased RFS or OS in patients with colorectal cancer who underwent liver resection.

METHODS

Patients with resected colorectal liver metastases who received adjuvant hepatic arterial infusion plus systemic therapy and for whom KRAS data was available were evaluated. Correlation between KRAS and clinical factors was done using the Fisher exact test. Kaplan-Meier methods were used to estimate the median RFS and OS.

RESULTS

A total of 169 patients were evaluated, 118 of whom had KRAS wild-type (WT) and 51 had KRAS mutated (MUT) tumors. The 3-year RFS rate was 46% for patients with KRAS WT (95% confidence interval [95% CI], 35%-56%) and 30% (95% CI, 16%-44%) for patients with KRAS MUT (P =.005). The 3-year OS rate was 95% (95% CI, 87%-98%) and 81% (95% CI, 62%-95%), respectively, for patients with KRAS WT and KRAS MUT (P =.07). On multivariate analysis, KRAS remained a significant predictor of RFS (hazard ratio, 1.9). The 3-year cumulative recurrence rate by site of metastases was as follows: 2% versus 13.4% for bone (P≤.01), 2% versus 14.5% for brain (P =.05), 33.2% versus 58% for lung (P≤.01), and 30% versus 47% for liver (P =.10) in patients with KRAS WT versus KRAS MUT.

CONCLUSIONS

In the current study, among patients with resected colorectal liver metastases who were treated with adjuvant hepatic arterial infusion plus systemic therapy, patients with KRAS MUT were found to have a significantly worse 3-year RFS (30%) compared with KRAS WT (46%) p=.005. The cumulative incidence of bone, brain, and lung metastases was significantly higher for patients with KRAS MUT compared with those with KRAS WT.

Adjuvant systemic chemotherapy with or without bevacizumab in patients with resected pulmonary metastases from colorectal cancer

INTRODUCTION

We investigated the impact of modern chemotherapy regimens and bevacizumab following pulmonary metastasectomy (PM) from metastatic colorectal cancer (CRC).

METHODS

A total of 122 consecutive patients who were curatively resected for pulmonary metastases of CRC in twelve oncology centers were retrospectively analysed between January 2000 and April 2012.

RESULTS

Of 122 patients, 14 did not receive any treatment following PM. The remaining 108 patients received fluoropyrimidine-based (n = 12), irinotecan-based (n = 56) and oxaliplatin-based (n = 40) chemotherapy combinations. Among these, 52 patients received bevacizumab (BEV) while 56 did not (NoBEV). Median recurrence-free survival (RFS) was 17 months and median overall survival (OS) has not been reached at a median follow-up of 25 months after PM. Three and five-year OS rates were 66% and 53%, respectively. RFS and OS were similar, irrespective of the chemotherapy regimen or BEV use. Positive pulmonary margin, KRAS mutation status, and previous liver metastasectomy were negative independent prognostic factors for RFS, while pathologically confirmed thoracic lymph node involvement was the only negative independent prognostic for OS in multivariate analysis.

CONCLUSIONS

No significant RFS or OS difference was observed in respect to chemotherapy regimens with or without BEV in patients with pulmonary metastases of CRC following curative resection.

The role of antiangiogenic agents in the treatment of patients with advanced colorectal cancer according to K-RAS status

Colorectal cancer (CRC) is the fourth most commonly diagnosed cancer worldwide. Recently, it has been found that about 40 % of patients with CRC have mutations in the K-RAS gene. Several clinical trials have showed that patients with metastatic colorectal cancer (mCRC) who present tumour-promoting mutations in signalling pathways involving the epidermal growth factor receptor (EGFR), which includes activating K-RAS mutations, do not respond to anti-EGFR drugs such as panitumumab and cetuximab. Hence, K-RAS status is now considered an important negative predictive factor for response to anti-EGFR drugs. Moreover, K-RAS status seems to have also a prognostic role in CRC, but this fact is somewhat controversial. Activity of antiangiogenic agents seems not to be influenced by K-RAS gene status. Tumour angiogenesis has attracted interest in attempts to improve the management of mCRC. The vascular endothelial growth factor (VEGF) pathway is fundamental to the regulation of angiogenesis, and research has focused on developing agents that selectively target it. In this way, the anti-VEGF antibody bevacizumab in combination with chemotherapy has provided important clinical benefits in terms of response rate, progression-free survival and overall survival to patients with mCRC. Efficacy data of bevacizumab in K-RAS wild-type patients seem to be comparable with the efficacy data observed with anti-EGFR therapies in a cross-trial comparison. Although there is a lack of prospective and randomized data in this setting, the combination of chemotherapy plus antiangiogenic agents could be considered as an effective alternative for the treatment of mCRC with independence of K-RAS gene status. Here, we review the available data we have in the literature of the use of antiangiogenic strategies in the treatment of mCRC nowadays.

Prognostic relevance of KRAS genotype in metastatic colorectal cancer patients unfit for FIr-B/FOx intensive regimen

First-line triplet chemotherapy plus bevacizumab (FIr-B/FOx) can improve efficacy of metastatic colorectal cancer (MCRC), KRAS wild-type and mutant. Prognostic relevance of KRAS genotype was evaluated in patients unfit for FIr-B/FOx, treated with conventional medical treatments. Consecutive MCRC patients not eligible for FIr-B/FOx regimen due to age (≥75 years) and/or comorbidities were treated with tailored conventional first-line treatments. KRAS codon 12/13 mutations were screened by direct sequencing. Activity and efficacy were evaluated and compared according to medical treatments, age (non-elderly and elderly≥65 years), comorbidity stage (Cumulative Illness Rating Scale), metastatic extension (liver-limited and other/multiple metastatic), and KRAS genotype, using log-rank. Selected first line treatments were medical in 37 patients (92.5%), and surgical in 3 patients (7.5%). Medical treatment regimens: triplet, 18 (45%); doublet, 15 (37.5%); mono-therapy, 4 (10%). At median follow-up of 8 months, objective response rate (ORR) was 37%, median progression-free survival (PFS) 7 months, liver metastasectomies 8% (liver-limited disease 37.5%), median overall survival (OS) 13 months. Triplet regimens failed to significantly affect clinical outcome, compared to doublet. According to KRAS genotype, ORR, PFS and OS were, respectively: wild-type 50%, 8 months, 13 months; mutant 25%, 6 months, 9 months. KRAS genotype wild-type compared to mutant significantly affected PFS, while not OS. KRAS c.35 G>A mutation (G12D) significantly affected worse PFS and OS compared to wild-type and/or other mutations. KRAS genotype, specifically the c.35 G>A KRAS mutation, may indicate poor prognosis in MCRC patients unfit for intensive medical treatments.

Metastatic colorectal cancer first-line treatment with bevacizumab: the impact of K-ras mutation

BACKGROUND

Bevacizumab plus chemotherapy prolongs progression-free survival (PFS) and overall survival (OS) in metastatic colorectal cancer (mCRC). Although there is strong evidence to suggest that the mutational status of the K-ras oncogene has a role as a predictive factor for activity in patients treated with cetuximab and panitumumab, few data have been obtained in patients treated with bevacizumab. We conducted an additional retrospective analysis to investigate the prognostic value of K-ras mutation relative to mCRC first-line treatment with bevacizumab.

MATERIALS AND METHODS

A total of 108 patients were retrospectively reviewed. K-ras status was assessed in the overall population by sequencing. Statistical association for PFS and OS was analyzed using the Kaplan-Meier method, and the prognostic role of K-ras was determined using the logrank test.

RESULTS

Median PFS was 10 months both for patients with wild-type (WT) K-ras and mutated (MT) K-ras (hazard ratio [HR] 0.94, P=0.75); neither difference in median OS was significant (27 months WT K-ras versus 26 months MT K-ras, HR 0.92; P=0.70). A further analysis was carried out in the two groups according to metastatic sites. No statistically significant difference in terms of PFS and OS was demonstrated between WT K-ras and MT K-ras with liver metastases only and in those with extrahepatic disease.

CONCLUSION

Although further study is required, our results seem to confirm that K-ras mutation does not have a prognostic role in mCRC patients receiving first-line treatment with bevacizumab.

Prognostic value of the combination of circulating tumor cells plus KRAS in patients with metastatic colorectal cancer treated with chemotherapy plus bevacizumab

OBJECTIVE

Circulating tumor cells (CTCs) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) status were identified as prognostic factors for progression-free survival (PFS) and overall survival (OS) in patients with metastatic colorectal cancer treated with chemotherapy and bevacizumab in analyses of the MACRO (Maintenance Treatment in Advanced Colorectal Cancer) trial. In this post hoc analysis of the MACRO trial, the potential additive effect of these 2 factors on patient outcomes was explored.

METHODS

A total of 158 of the 480 patients involved in the MACRO trial were included in the biological marker substudy. CTC isolation and enumeration were centralized and performed using the CellSearch System (Veridex LLC, Raritan, NJ) in 7.5 mL of whole blood. Evaluation of KRAS status was performed retrospectively by the standard method used at each center. PFS and OS were analyzed by the Kaplan-Meier method according to CTC count and KRAS status.

RESULTS

Patients with < 3 CTC per 7.5 mL blood at baseline and KRAS wild-type tumors had a median PFS of 14.2 months compared with 6.2 months in patients with ≥ 3 CTCs and KRAS mutated tumors (P < .0001; hazard ratio, 3.0; 95% confidence interval, 1.8-5.2). Similar findings were observed for OS (28.9 and 13.7 months, respectively, P = .0004; hazard ratio 2.8; 95% confidence interval, 1.6-4.9). Multivariate analyses showed that CTC count ≥ 3 and KRAS status were the only independent prognostic factors for both PFS and OS.

CONCLUSIONS

This post hoc analysis showed that CTC count and KRAS status were independent prognostic factors for outcomes in patients with metastatic colorectal cancer treated with bevacizumab ± chemotherapy. These factors should be taken into account in the design of future phase III trials.

KRAS as prognostic biomarker in metastatic colorectal cancer patients treated with bevacizumab: a pooled analysis of 12 published trials

The significance of KRAS in advanced colorectal cancer (CRC) treated with bevacizumab (B) is not well understood. We conducted a systematic review and pooled analysis of published trials with the aim to assess the predictive and prognostic role of KRAS status in patients treated with B. We performed a systematic search of PubMed, EMBASE, Web of Science, and Cochrane Register of Controlled Trials. The primary endpoints included objective response rate (RR), progression-free survival (PFS), and overall survival (OS). The odds ratio (OR) for RR and hazard ratios (HRs) were calculated or extracted by published data either using a fixed effect model or a random effect model. A total of 12 studies were included. A total of 2,266 patients were analysed (54 % were KRAS wt). The pooled RRs for KRAS wild-type (wt) versus mutated (mut) patients were 54.8 and 48.3 %, respectively (OR 1.42, P = 0.02). Median PFS was significantly longer in KRAS wt patients compared with that in KRAS mut patients (HR = 0.85; 95 % confidence interval (CI) 0.74-0.98; P = 0.02). Similarly, median OS was significantly better in wt KRAS patients compared with that in mut KRAS patients (HR = 0.65; 95 % CI 0.46-0.92; P = 0.01). This pooled analysis of 12 published studies shows that KRAS wt status is a good prognostic factor for B-based chemotherapy. Also, KRAS wt CRC is associated with a better RR with B plus chemotherapy than mut counterpart.

The impact of KRAS mutations on VEGF-A production and tumour vascular network

Background

The malignant potential of tumour cells may be influenced by the molecular nature of KRAS mutations being codon 13 mutations less aggressive than codon 12 ones. Their metabolic profile is also different, with an increased anaerobic glycolytic metabolism in cells harbouring codon 12 KRAS mutations compared with cells containing codon 13 mutations. We hypothesized that this distinct metabolic behaviour could be associated with different HIF-1α expression and a distinct angiogenic profile.

Methods

Codon13 KRAS mutation (ASP13) or codon12 KRAS mutation (CYS12) NIH3T3 transfectants were analyzed in vitro and in vivo. Expression of HIF-1α, and VEGF-A was studied at RNA and protein levels. Regulation of VEGF-A promoter activity was assessed by means of luciferase assays using different plasmid constructs. Vascular network was assessed in tumors growing after subcutaneous inoculation. Non parametric statistics were used for analysis of results.

Results

Our results show that in normoxic conditions ASP13 transfectants exhibited less HIF-1α protein levels and activity than CYS12. In contrast, codon 13 transfectants exhibited higher VEGF-A mRNA and protein levels and enhanced VEGF-A promoter activity. These differences were due to a differential activation of Sp1/AP2 transcription elements of the VEGF-A promoter associated with increased ERKs signalling in ASP13 transfectants. Subcutaneous CYS12 tumours expressed less VEGF-A and showed a higher microvessel density (MVD) than ASP13 tumours. In contrast, prominent vessels were only observed in the latter.

Conclusion

Subtle changes in the molecular nature of KRAS oncogene activating mutations occurring in tumour cells have a major impact on the vascular strategy devised providing with new insights on the role of KRAS mutations on angiogenesis.

Molecular markers to predict outcome to antiangiogenic therapies in colorectal cancer: current evidence and future perspectives

Angiogenesis is a universal requirement for the growth of solid tumours beyond the limits of oxygen diffusion from the existing vasculature. The expression and function of proangiogenic and antiangiogenic factors are altered in solid malignancies to drive net neoangiogenesis. Vascular endothelial growth factor (VEGF) has been confirmed in several clinical trials as an important therapeutic target in colorectal cancer (CRC) treatment. However, given that the efficacy of antiangiogenic agents appears to be limited to a subset of patients, the identification of who will obtain the greater benefit from this therapy or suffer from specific toxicities and when or for how long they should be administered in the treatment algorithm are major open questions for clinicians and challenges for present and future research. Current evidence indicates some predictive value for particular circulating measures, such as an increase in VEGF, a decrease in vascular endothelial growth factor receptor 2 (VEGFR-2) or circulating endothelial cells, tissue biomarkers, microvessel density, KRAS and BRAF gene mutations or polymorphisms affecting components of the VEGF pathway. Many questions relating to these and other surrogate biomarkers, however, remain unanswered and their clinical usefulness has yet to be proven. This review will focus on the present status of knowledge and future perspectives for developing molecular tools to foresee and monitor antiangiogenic therapy activity in CRC patients.