Targeted therapy for biliary tract cancers

Biliary tract cancers (BTCs) are a heterogeneous group of malignancies, with a historically poor prognosis as a whole. Until recently, the development of effective therapeutics was hampered by the relatively low incidence, heterogeneity in patients and tumors, and correspondingly poor clinical trial enrollments. With the publication of the landmark phase III ABC-02 trial demonstrating the superiority of gemcitabine and cisplatin combination chemotherapy, the landscape changed for the development of new agents. Despite this progress, there are currently no approved targeted agents for BTC. This review will focus on recent developments in targeted therapeutics, directed against several key signaling pathways in BTC, including epidermal growth factor receptor, angiogenesis, and the mitogen-activated protein kinase pathway. Data from recent phase I and II trials will be discussed, along with a preview of upcoming trials involving targeted therapies.

Colorectal liver metastases

BACKGROUND

With modern multimodality therapy, patients with resected colorectal cancer (CRC) liver metastases (CLM) can experience up to 50-60 % 5-year survival. These improved outcomes have become more commonplace via achievements in multidisciplinary care, improved definition of resectability, and advances in technical skill.

DISCUSSION

Even patients with synchronous and/or extensive bilateral disease have benefited from novel surgical strategies. Treatment sequencing of synchronous CRC with CLM can be simplified into the following three paradigms: (classic colorectal-first), simultaneous (combined), or reverse approach (liver-first). The decision of whether to treat the CLM or CRC first depends on which site dominates oncologically and symptomatically. Oxaliplatin with 5-fluorouracil/leucovorin (FOLFOX) and irinotecan with 5-fluorouracil/leucovorin (FOLFIRI) are the foundations of modern chemotherapy. Although each regimen has positively impacted survivals, both have the potential for negative effects on the non-tumor liver. Oxaliplatin is associated with vascular injury (sinusoidal ballooning, microvascular injury, nodular regenerative hyperplasia, and long-term fibrosis) but not steatosis. Irinotecan has been associated with steatohepatitis, especially in patients with obesity and diabetes. Steatohepatitis from irinotecan is the only chemotherapy-associated liver injury (CALI) associated with increased mortality from postoperative hepatic insufficiency. Extended duration of preoperative chemotherapy is also associated with CALI.

CONCLUSIONS

To determine resectability and to prevent overtreatment with systemic therapy, all patients should receive high-quality cross-sectional imaging and be evaluated by a hepatobiliary surgeon before starting chemotherapy. Even as chemotherapy improves, liver surgeons will continue to play a central role in treatment planning by offering the best chance for prolonged survival-safe R0 resection with curative intent.

The role of cetuximab as first-line treatment of colorectal liver metastases

INTRODUCTION

Recent advancements in the management of colorectal liver metastases have resulted in an improvement in survival. Novel biomarkers such as KRAS, and their mutations potentially predict the response of biological therapies such as cetuximab (Erbitux). This paper evaluates the use of cetuximab in the first-line management of colorectal liver metastases.

METHODS

An electronic literature search was performed of publications within the past 6 years. The following key words, singly or in combination, were used: KRAS, cetuximab, metastatic colorectal cancer and colorectal liver metastases. All randomized controlled trials and cohort studies were included.

RESULTS

Fifteen prospective studies reviewed the clinical application of cetuximab. Seven studies included sub-group analysis of KRAS mutational status, with only one study performed prospectively. Until the MRC COIN trial, the evidence consistently demonstrated cetuximab significantly improved progression-free survival, overall survival and surgical resection rates, especially in KRAS wild-type tumours. However, the MRC COIN trial found cetuximab had no additional benefit when combined with standard chemotherapy.

CONCLUSIONS

The literature does not support the routine use of cetuximab as the standard first-line treatment of colorectal liver metastases, rather highlighting the need for the optimization of treatment on an individual basis, especially depending on tumour KRAS status.

Modern prospection for hepatic arterial infusion chemotherapy in malignancies with liver metastases

Malignancy with liver metastasis plays an important role in daily oncology practice, especially for primary cancers of the gastrointestinal tract and hepatopancreatobiliary system. On account of the dual vascular supply system and the fact that most metastatic liver tumors are supplied by the hepatic artery, hepatic artery infusion chemotherapy (HAIC) is an appealing method for the treatment of liver metastases. Herein, we summarize recent study results reported in the literature regarding the use of HAIC for metastatic liver tumors, with special focus on colorectal cancer.

Biologic agents in the treatment of colorectal cancer: the last decade; the lost decade?

KEY POINTS

After almost 40 years of minimal progress, the period from 1996 to 2003 saw a flurry of new drugs become available.

Progress since 2003 has been minimal.

Most new agents with activity in the metastatic setting (irinotecan, bevacizumab, cetuximab) do not have activity in the adjuvant setting and so have not increased the cure rate.

Combinations of biologics have been disappointing.

Progress to date is less than we would have expected.

Therapy individualized according to molecular characterization of each tumor appears to be the way forward.

Colorectal liver metastases

BACKGROUND

With modern multimodality therapy, patients with resected colorectal cancer (CRC) liver metastases (CLM) can experience up to 50-60 % 5-year survival. These improved outcomes have become more commonplace via achievements in multidisciplinary care, improved definition of resectability, and advances in technical skill.

DISCUSSION

Even patients with synchronous and/or extensive bilateral disease have benefited from novel surgical strategies. Treatment sequencing of synchronous CRC with CLM can be simplified into the following three paradigms: (classic colorectal-first), simultaneous (combined), or reverse approach (liver-first). The decision of whether to treat the CLM or CRC first depends on which site dominates oncologically and symptomatically. Oxaliplatin with 5-fluorouracil/leucovorin (FOLFOX) and irinotecan with 5-fluorouracil/leucovorin (FOLFIRI) are the foundations of modern chemotherapy. Although each regimen has positively impacted survivals, both have the potential for negative effects on the non-tumor liver. Oxaliplatin is associated with vascular injury (sinusoidal ballooning, microvascular injury, nodular regenerative hyperplasia, and long-term fibrosis) but not steatosis. Irinotecan has been associated with steatohepatitis, especially in patients with obesity and diabetes. Steatohepatitis from irinotecan is the only chemotherapy-associated liver injury (CALI) associated with increased mortality from postoperative hepatic insufficiency. Extended duration of preoperative chemotherapy is also associated with CALI.

CONCLUSIONS

To determine resectability and to prevent overtreatment with systemic therapy, all patients should receive high-quality cross-sectional imaging and be evaluated by a hepatobiliary surgeon before starting chemotherapy. Even as chemotherapy improves, liver surgeons will continue to play a central role in treatment planning by offering the best chance for prolonged survival-safe R0 resection with curative intent.

Subtypes of primary colorectal tumors correlate with response to targeted treatment in colorectal cell lines

Background

Colorectal cancer (CRC) is a heterogeneous and biologically poorly understood disease. To tailor CRC treatment, it is essential to first model this heterogeneity by defining subtypes of patients with homogeneous biological and clinical characteristics and second match these subtypes to cell lines for which extensive pharmacological data is available, thus linking targeted therapies to patients most likely to respond to treatment.

Methods

We applied a new unsupervised, iterative approach to stratify CRC tumor samples into subtypes based on genome-wide mRNA expression data. By applying this stratification to several CRC cell line panels and integrating pharmacological response data, we generated hypotheses regarding the targeted treatment of different subtypes.

Results

In agreement with earlier studies, the two dominant CRC subtypes are highly correlated with a gene expression signature of epithelial-mesenchymal-transition (EMT). Notably, further dividing these two subtypes using iNMF (iterative Non-negative Matrix Factorization) revealed five subtypes that exhibit activation of specific signaling pathways, and show significant differences in clinical and molecular characteristics. Importantly, we were able to validate the stratification on independent, published datasets comprising over 1600 samples. Application of this stratification to four CRC cell line panels comprising 74 different cell lines, showed that the tumor subtypes are well represented in available CRC cell line panels. Pharmacological response data for targeted inhibitors of SRC, WNT, GSK3b, aurora kinase, PI3 kinase, and mTOR, showed significant differences in sensitivity across cell lines assigned to different subtypes. Importantly, some of these differences in sensitivity were in concordance with high expression of the targets or activation of the corresponding pathways in primary tumor samples of the same subtype.

Conclusions

The stratification presented here is robust, captures important features of CRC, and offers valuable insight into functional differences between CRC subtypes. By matching the identified subtypes to cell line panels that have been pharmacologically characterized, it opens up new possibilities for the development and application of targeted therapies for defined CRC patient sub-populations.

Predictive value of epidermal growth factor receptor expression for first-line chemotherapy plus cetuximab in patients with head and neck and colorectal cancer: analysis of data from the EXTREME and CRYSTAL studies

BACKGROUND

The phase III EXTREME and CRYSTAL studies demonstrated that the addition of cetuximab to chemotherapy significantly improved survival in the first-line treatment of recurrent/metastatic squamous cell carcinoma of the head and neck (SCCHN) and KRAS wild-type metastatic colorectal cancer (mCRC). In advanced non-small-cell lung cancer (NSCLC), high EGFR expression was identified as a tumour biomarker that can predict survival benefit associated with the addition of cetuximab to first-line chemotherapy. We investigated whether tumour EGFR expression level was predictive of cetuximab benefit in EXTREME and CRYSTAL study patients.

METHODS

Prospectively collected tumour immunohistochemistry data were used to generate an EGFR immunohistochemistry score (scale 1-300) for patients in the EXTREME and CRYSTAL studies. For each study, the association between tumour immunohistochemistry score and cetuximab benefit was investigated. The EXTREME and CRYSTAL studies are registered with Clinical Trials.gov, numbers NCT00122460 and NCT00154102, respectively.

FINDINGS

Tumour EGFR immunohistochemistry data were available for 411 of 442 (93%) patients from the EXTREME study intention-to-treat (ITT) population and 664 of 666 (100%) patients from the ITT population of the CRYSTAL study with EGFR-expressing, KRAS wild-type disease. The distribution of immunohistochemistry scores was similar between the treatment arms of each study, but differed between studies. A clinically relevant benefit for progression-free and overall survival associated with the addition of cetuximab to chemotherapy was seen across the full score range in EXTREME study patients. Similarly, CRYSTAL study patients derived a clinical benefit across the full score range, with no meaningful association between EGFR expression level and benefit.

INTERPRETATION

The addition of cetuximab to chemotherapy improved survival in the first-line treatment of recurrent/metastatic SCCHN and KRAS wild-type mCRC regardless of tumour EGFR expression level, indicating that in contrast to findings in NSCLC, EGFR expression level is not a clinically useful predictive biomarker in these settings.

Hotspot oncomutations: implications for personalized cancer treatment

Understanding the extent to which specific tumor mutations impact or mediate patient response to particular cancer therapies has become a rapidly increasing area of research. Recent research findings regarding four predominant mutational targets (KRAS, BRAF, EGFR and PIK3CA) show that these tumor mutations have predictive power for identifying which patients are likely to respond to particular therapies, and have prognostic significance irrespective of treatment. However, in this regard, the literature is frequently nuanced and sometimes contradictory. This lack of clarity may be due, at least in part, to the utilization of mutation detection methods with varying sensitivities across studies of different patient populations. Nevertheless, considerable evidence suggests minor tumor subpopulations may be contributing to inappropriate patient stratification, development of resistance to treatment, and the relapse that often follows treatment with molecularly targeted therapies. Consequently, mutant tumor subpopulations need to be considered in order to improve strategies for personalized cancer treatment.

Direct and immune mediated antibody targeting of ERBB receptors in a colorectal cancer cell-line panel

A significant proportion of colorectal cancer (CRC) patients are resistant to anti-ERBB1 [avian erythroblastic leukemia viral (v-erb-b) oncogene homolog, receptor for EGF] monoclonal antibodies (Mabs). We evaluated both immune and nonimmune effects of cetuximab (anti-ERBB1 Mab), trastuzumab (anti-ERBB2 Mab), pertuzumab (anti-ERBB2 Mab), and lapatinib (dual ERBB1 and ERBB2 tyrosine kinase inhibitor) in a large well-characterized panel of 64 CRC cell lines to find response predictive tumor characteristics. There was a significant correlation between the direct effects of cetuximab and lapatinib. Both agents were associated (P = 0.0004) with "triple' wild-type status in KRAS, BRAF, and PIK3CA exon 20. Most cell lines were resistant to the direct effects of anti-ERBB2 Mabs, suggesting that the effects of lapatinib might mainly be through ERBB1. Microarray mRNA expression profiles of sensitive and resistant cell lines showed that although ERBB1 receptor or ligand levels did not associate with cetuximab sensitivity, high levels of ERBB2 (P = 0.036) and amphiregulin (P = 0.026) predicted sensitivity to lapatinib. However, higher ERBB1 expression predicted susceptibility to cetuximab-induced antibody-dependent cellular cytotoxicity and occurred independently of KRAS/BRAF/PIK3CA mutations (P = 0.69). Lapatinib may be an effective alternative therapy to cetuximab in triple wild-type tumors. Microarray analysis provides suggestive biomarkers for resistance. ERBB1 levels, independent of mutation status, predict immune killing. Therefore, anti-ERBB1 antibodies may be considered in CRC tumors with higher ERBB1 expression and favorable FcγR polymorphisms.

Epithelial mesenchymal transition in colorectal cancer: Seminal role in promoting disease progression and resistance to neoadjuvant therapy

BACKGROUND

Epithelial mesenchymal transition (EMT) may be physiological as part of embryological development, or pathological as part of cancer development. It is one of the key initiating events in the metastatic cascade. EMT has profound effects on tumour cell invasiveness, proliferation and motility. In the present article we aimed to review the potential role of EMT as a process to explain colorectal cancer progression and resistance to neoadjuvant therapy.

METHODS

Extensive literature searches were performed in Pubmed, EMBASE and Google Scholar databases to identify relevant articles published before March 2012.

RESULTS

There is adequate evidence to support the complex upstream signalling alterations needed for EMT to occur in colorectal cancers. Changes of EMT are likely to be found at the tumour invasive front: the deepest, growing tumour margin. Loss of E-cadherin at the cell membrane causes loss of cellular integrity, with subsequent migration of malignant cells and tumour budding. These processes are associated with metastases and recurrence of colorectal cancer. There is early evidence from a limited number of studies that resistance to neoadjuvant therapy in colorectal cancer is associated with changes of EMT. However, there is a lack of supporting evidence originating from human colorectal cancer tissues.

CONCLUSIONS

Emerging evidence demonstrates that development of EMT in colorectal cancer leads to an aggressive phenotype that may promote metastatic spread, and augment treatment resistance during neoadjuvant therapy. A clearer understanding of the processes and role of EMT in colorectal cancer may also highlight novel therapeutic strategies.

Prognostic relevance of KRAS and BRAF mutations in Japanese patients with colorectal cancer

BACKGROUND

Mutations of the KRAS or BRAF genes are now recognized as prognostic markers for colorectal cancer (CRC). They are also important predictive markers for resistance to the monoclonal antibodies that target the epidermal growth factor receptor.

METHODS

In this retrospective study, KRAS and BRAF mutations were analyzed using a direct sequence method in 254 Japanese CRC patients, and the associations between KRAS or BRAF mutations and clinicopathological characteristics or outcome were evaluated.

RESULTS

KRAS and BRAF mutations were detected in 33.5 and 6.7 % of all patients, respectively. Consistent with previous reports, BRAF mutations were significantly correlated with the anatomical site of the tumor (P < 0.001), tumor grade (P = 0.001) and high frequency of microsatellite instability (P < 0.001). BRAF mutations were correlated with poor overall survival in the full patient cohort (P = 0.009). KRAS mutations were significantly correlated with poor recurrence-free survival (P = 0.03), particularly in patients with stage II CRC (P = 0.007). Cox regression analysis showed that KRAS mutations were a negative predictor of recurrence-free survival in patients with stage II CRC.

CONCLUSION

KRAS mutation status could be a novel biomarker for predicting disease recurrence in Japanese patients with stage II CRC.

Cost-effectiveness analysis of screening for KRAS and BRAF mutations in metastatic colorectal cancer

BACKGROUND

In 2009, the American Society of Clinical Oncology recommended that patients with metastatic colorectal cancer (mCRC) who are candidates for anti-epidermal growth factor receptor (EGFR) therapy have their tumors tested for KRAS mutations because tumors with such mutations do not respond to anti-EGFR therapy. Limiting anti-EGFR therapy to those without KRAS mutations will reserve treatment for those likely to benefit while avoiding unnecessary costs and harm to those who would not. Similarly, tumors with BRAF genetic mutations may not respond to anti-EGFR therapy, though this is less clear. Economic analyses of mutation testing have not fully explored the roles of alternative therapies and resection of metastases.

METHODS

This paper is based on a decision analytic framework that forms the basis of a cost-effectiveness analysis of screening for KRAS and BRAF mutations in mCRC in the context of treatment with cetuximab. A cohort of 50 000 patients with mCRC is simulated 10 000 times, with attributes randomly assigned on the basis of distributions from randomized controlled trials.

RESULTS

Screening for both KRAS and BRAF mutations compared with the base strategy (of no anti-EGFR therapy) increases expected overall survival by 0.034 years at a cost of $22 033, yielding an incremental cost-effectiveness ratio of approximately $650 000 per additional year of life. Compared with anti-EGFR therapy without screening, adding KRAS testing saves approximately $7500 per patient; adding BRAF testing saves another $1023, with little reduction in expected survival.

CONCLUSIONS

Screening for KRAS and BFAF mutation improves the cost-effectiveness of anti-EGFR therapy, but the incremental cost effectiveness ratio remains above the generally accepted threshold for acceptable cost effectiveness ratio of $100 000/quality adjusted life year.

Oncological management of unresectable liver metastases

Surgical resection of liver metastases of colorectal cancer can improve clinical outcome and even cure some patients with metastatic disease. For patients with unresectable liver metastases, the ultimate treatment goal is to let them become eligible for resection. In recent years, considerable attention has been paid to molecular targeted therapies to improve the efficacy of the available chemotherapeutic regimens in order to increase the downsizing rate of liver metastases and increase resectability. This overview will focus on the oncological management and chemotherapeutic options of patients with unresectable liver metastases.

Let-7 miRNA-binding site polymorphism in the KRAS 3'UTR; colorectal cancer screening population prevalence and influence on clinical outcome in patients with metastatic colorectal cancer treated with 5-fluorouracil and oxaliplatin +/- cetuximab

BACKGROUND

Recent studies have reported associations between a variant allele in a let-7 microRNA complementary site (LCS6) within the 3'untranslated region (3'UTR) of KRAS (rs61764370) and clinical outcome in metastatic colorectal cancer (mCRC) patients receiving cetuximab. The variant allele has also been associated with increased cancer risk. We aimed to reveal the incidence of the variant allele in a colorectal cancer screening population and to investigate the clinical relevance of the variant allele in mCRC patients treated with 1st line Nordic FLOX (bolus 5-fluorouracil/folinic acid and oxaliplatin) +/- cetuximab.

METHODS

The feasibility of the variant allele as a risk factor for CRC was investigated by comparing the LCS6 gene frequencies in 197 CRC patients, 1060 individuals with colorectal polyps, and 358 healthy controls. The relationship between clinical outcome and LCS6 genotype was analyzed in 180 mCRC patients receiving Nordic FLOX and 355 patients receiving Nordic FLOX + cetuximab in the NORDIC-VII trial (NCT00145314).

RESULTS

LCS6 frequencies did not vary between CRC patients (23%), individuals with polyps (20%), and healthy controls (20%) (P = 0.50). No statistically significant differences were demonstrated in the NORDIC-VII cohort even if numerically increased progression-free survival (PFS) and overall survival (OS) were found in patients with the LCS6 variant allele (8.5 (95% CI: 7.3-9.7 months) versus 7.8 months (95% CI: 7.4-8.3 months), P = 0.16 and 23.5 (95% CI: 21.6-25.4 months) versus 19.5 months (95% CI: 17.8-21.2 months), P = 0.31, respectively). Addition of cetuximab seemed to improve response rate more in variant carriers than in wild-type carriers (from 35% to 57% versus 44% to 47%), however the difference was not statistically significant (interaction P = 0.16).

CONCLUSIONS

The LCS6 variant allele does not seem to be a risk factor for development of colorectal polyps or CRC. No statistically significant effect of the LCS6 variant allele on response rate, PFS or OS was found in mCRC patients treated with 1st line Nordic FLOX +/- cetuximab.

Progression-free survival as a surrogate endpoint for median overall survival in metastatic colorectal cancer: literature-based analysis from 50 randomized first-line trials

PURPOSE

To evaluate progression-free survival (PFS) as a potential surrogate endpoint (SEP) for overall survival (OS) in metastatic colorectal cancer (mCRC) with a focus on applicability to trials containing targeted therapy with anti-VEGF- or anti-EGF receptor (EGFR)-directed monoclonal antibodies.

EXPERIMENTAL DESIGN

A systematic literature search of randomized trials of first-line chemotherapy for mCRC reported from January 2000 to January 2012 was conducted. Adjusted weighted linear regression was used to calculate correlations within PFS and OS (endpoints; R(EP)) and between treatment effects on PFS and on OS (treatment effects; R(TE)).

RESULTS

Fifty trials reflecting 22,736 patients met the inclusion criteria. Correlation between treatment effects on PFS and OS and between the endpoints PFS and OS was high across all studies (R(TE) = 0.87, R(EP) = 0.86). This was also observed in chemotherapy-only trials (R(TE) = 0.93, R(EP) = 0.81) but less so for trials containing monoclonal antibodies (R(TE) = 0.47; R(EP) = 0.52). Limiting the analysis to bevacizumab-based studies (11 trials, 3,310 patients) again yielded high correlations between treatment effects on PFS and on OS (R(TE) = 0.84), whereas correlation within PFS and OS was low (R(EP) = 0.45). In 7 trials (1,335 patients) investigating cetuximab- or panitumumab-based studies, contrasting correlations with very wide confidence intervals were observed (R(TE) = 0.28; R(EP) = 0.96).

CONCLUSIONS

PFS showed consistently high correlation with OS of an order that would justify its use as an SEP in chemotherapy regimens. For validation of surrogacy in anti-VEGF and anti-EGFR-directed therapies, further research and a larger set of trials is needed.

Association of hypomagnesemia with inferior survival in a phase III, randomized study of cetuximab plus best supportive care versus best supportive care alone: NCIC CTG/AGITG CO.17

BACKGROUND

Cetuximab-induced hypomagnesemia has been associated with improved clinical outcomes in advanced colorectal cancer (CRC). We explored this relationship from a randomized clinical trial of cetuximab plus best supportive care (BSC) versus BSC alone in patients with pretreated advanced CRC.

PATIENTS AND METHODS

Day 28 hypomagnesemia grade (0 versus ≥1) and percent reduction (<20% versus ≥20%) of Mg from baseline was correlated with outcome.

RESULTS

The median percentage Mg reduction at day 28 was 10% (-42.4% to 63.0%) for cetuximab (N = 260) versus 0% (-21.1% to 25%) for BSC (N = 251) [P < 0.0001]. Grade ≥1 hypomagnesemia and ≥20% reduction from baseline at day 28 were associated with worse overall survival (OS) [hazard ratio, HR 1.61 (95% CI 1.12-2.33), P = 0.01 and 2.08 (95% CI 1.32-3.29), P = 0.002, respectively] in multivariate analysis including grade of rash (0-1 versus 2+). Dyspnea (grade ≥3) was more common in patients with ≥20% versus < 20% Mg reduction (68% versus 45%; P = 0.02) and grade 3/4 anorexia were higher in patients with grade ≥1 hypomagnesemia (81% versus 63%; P = 0.02).

CONCLUSIONS

In contrast to prior reports, cetuximab-induced hypomagnesemia was associated with poor OS, even after adjustment for grade of rash.

Survival after liver resection in metastatic colorectal cancer: review and meta-analysis of prognostic factors

Background

Hepatic metastases develop in approximately 50% of colorectal cancer (CRC) cases. We performed a review and meta-analysis to evaluate survival after resection of CRC liver metastases (CLMs) and estimated the summary effect for seven prognostic factors.

Methods

Studies published between 1999 and 2010, indexed on Medline, that reported survival after resection of CLMs, were reviewed. Meta-relative risks for survival by prognostic factor were calculated, stratified by study size and annual clinic volume. Cumulative meta-analysis results by annual clinic volume were plotted.

Results

Five- and 10-year survival ranged from 16% to 74% (median 38%) and 9% to 69% (median 26%), respectively, based on 60 studies. The overall summary median survival time was 3.6 (range: 1.7–7.3) years. Meta-relative risks (95% confidence intervals) by prognostic factor were: node positive primary, 1.6 (1.5–1.7); carcinoembryonic antigen level, 1.9 (1.1–3.2); extrahepatic disease, 1.9 (1.5–2.4); poor tumor grade, 1.9 (1.3–2.7); positive margin, 2.0 (1.7–2.5); >1 liver metastases, 1.6 (1.4–1.8); and >3 cm tumor diameter, 1.5 (1.3–1.8). Cumulative meta-analyses by annual clinic volume suggested improved survival with increasing volume.

Conclusion

The overall median survival following CLM liver resection was 3.6 years. All seven investigated prognostic factors showed a modest but significant predictive relationship with survival, and certain prognostic factors may prove useful in determining optimal therapeutic options. Due to the increasing complexity of surgical interventions for CLM and the inclusion of patients with higher disease burdens, future studies should consider the potential for selection and referral bias on survival.

Therapeutic antibodies against cancer

Antibody-based therapeutics against cancer are highly successful and currently enjoy unprecedented recognition of their potential; 13 monoclonal antibodies (mAbs) have been approved for clinical use in the European Union and in the United States. Bevacizumab, rituximab, and trastuzumab had sales in 2010 of more than $5 billion each. Hundreds of mAbs, including bispecific mAbs and multispecific fusion proteins, mAbs conjugated with small-molecule drugs, and mAbs with optimized pharmacokinetics, are in clinical trials. However, deeper understanding of mechanisms is needed to overcome major problems including resistance to therapy, access to targets, complexity of biological systems, and individual variations.

Cetuximab plus cisplatin, irinotecan, and thoracic radiotherapy as definitive treatment for locally advanced, unresectable esophageal cancer: a phase-II study of the SWOG (S0414)

INTRODUCTION

The specific aims of the study were to evaluate the 2-year overall survival (OS) and progression-free survival (PFS), toxicity profile, and best objective response rate in patients with locally advanced, clinically unresectable esophageal cancer receiving cetuximab, cisplatin, irinotecan, and thoracic radiotherapy (TRT) within a multi-institutional cooperative-group setting.

METHODS

Eligible patients (cT4 M0 or medically unresectable, biopsy proven, and noncervical esophageal cancer) were to receive four 21-day cycles of cetuximab 400 mg/m (day 1, cycle 1), cetuximab 250 mg/m (day 8, 15, cycle 1; then days 1, 8, and 15 for subsequent cycles), cisplatin 30 mg/m (days 1 and 8, all cycles), and irinotecan 65 mg/m (days 1 and 8, all cycles). TRT was administered at 1.8 Gy in 28 daily fractions to a total dose of 50.4 Gy, to begin with on day 1 of cycle 3. The primary endpoint was 2-year OS, with an accrual goal of 75 patients with adenocarcinoma.

RESULTS

The study was closed because of slow accrual, with 21 eligible patients (11 squamous, 10 adenocarcinoma) enrolled from May 2005 to September 2007. Two-year OS and PFS (95% confidence interval [CI]) were 33.3% (14.6-57.0%) and 23.8% (8.2-47.2%), respectively. Kaplan-Meier estimates of median (95% CI) OS and PFS were 11.2 (6.4-43.6) and 6.4 (3.7-12.0) months, respectively. The overall response rate (95% CI) among 17 evaluable patients was 17.6% (3.8-43.4%), including 6% confirmed complete responders and 12% unconfirmed partial responders. Two deaths resulted from protocol treatment (sudden death and gastrointestinal necrosis). Ten (47.6%) and 6 (28.6%) patients had grade-3 or -4 toxicity, respectively: 52.4% were hematologic, 23.8% had fatigue, 19.0% had nausea, 19.0% had dehydration, and 19.0% had anorexia.

CONCLUSIONS

Concomitant cetuximab, cisplatin, irinotecan, and TRT were poorly tolerated in the first North American cooperative group trial testing this regimen for locally advanced esophageal cancer as treatment-related mortality approached 10%. Single-institution phase-II cetuximab-based combined modality trials have yielded encouraging results in preliminary analyses. The SWOG GI Committee endorses enrollment to open clinical trials to clarify the therapeutic ratio of cetuximab-based combined modality approaches for esophageal cancer.

Concordant KRAS mutations in primary and metastatic colorectal cancer tissue specimens: a meta-analysis and systematic review

A meta-analysis was performed to compare KRAS gene mutations in colorectal cancer tissue samples with primary and metastatic colorectal cancers. A total of 19 publications with 986 paired primary and distant metastases and 171 paired primary and lymph node metastases showed that KRAS genotype was highly concordant in primary and distant metastatic tumors, indicating that either type of tumor tissue could be useful as a source to detect KRAS mutations for selection of anti-EGFR therapy. However, lymph-node-metastatic tumors might not be suitable for diagnostic analysis of KRAS mutations due to an obvious discordant rate between primary and lymph-node-metastatic tumors.

Impact of STAT3 phosphorylation on the clinical effectiveness of anti-EGFR-based therapy in patients with metastatic colorectal cancer

Half of patients with KRAS wild-type colorectal cancer do not benefit from adding anti-epithelial growth factor receptor (EGFR) to standard chemotherapy regimens. This retrospective study was performed in 94 patients with metastatic colorectal cancer (mCRC) treated in the second line with cetuximab and chemotherapy. Signal transducer and activator of transcription 3 (STAT3) phosphorylation in tumor cells was correlated with decreased median progression-free survival and overall survival (OS). These results highlight the potential role of STAT3 as a molecular target to optimize anti-EGFR therapies.

BACKGROUND

Signal transducer and activator of transcription 3 (STAT3) is involved in epithelial growth factor receptor (EGFR) signaling in a KRAS-independent manner. Phosphorylated STAT3 (pSTAT3) expression in patients with metastatic colorectal cancer (mCRC) treated with anti-EGFR-containing salvage chemotherapy has never been investigated.

PATIENTS AND METHODS

: The first endpoint of this retrospective study was to evaluate the impact of pSTAT3 on the time to progression (TTP) in 94 patients with mCRC treated with anti-EGFR-based therapies in the second- or third-line setting between July 2004 and November 2009. The influence of pSTAT3 on objective response rate and overall survival (OS) was also reported. Nuclear expression of pSTAT3 status was evaluated by immunohistochemical tests on formalin-fixed and paraffin-embedded tumor samples obtained before therapy.

RESULTS

Positive expression of pSTAT3 was observed in 24.5% of the tumor samples. The probability of achieving an objective response was 13% among patients with positive nuclear expression of pSTAT3 compared with 41% for patients displaying pSTAT3-negative tumors (P = .02). In a multivariate logistic regression model, high-grade skin rash, wild-type KRAS status, and negative pSTAT3 status significantly improved TTP and OS.

CONCLUSION

These results underscore an impact of pSTAT3 on the clinical efficacy of anti-EGFR-containing chemotherapy regimens and support the prospective assessment of this biomarker.

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

BACKGROUND

In the MACRO study, patients with metastatic colorectal cancer (mCRC) were randomised to first-line treatment with 6 cycles of capecitabine and oxaliplatin (XELOX) plus bevacizumab followed by either single-agent bevacizumab or XELOX plus bevacizumab until disease progression. An additional retrospective analysis was performed to define the prognostic value of tumour KRAS status on progression-free survival (PFS), overall survival (OS) and response rates.

METHODOLOGY/PRINCIPAL FINDINGS

KRAS data (tumour KRAS status and type of mutation) were collected by questionnaire from participating centres that performed KRAS analyses. These data were then cross-referenced with efficacy data for relevant patients in the MACRO study database. KRAS status was analysed in 394 of the 480 patients (82.1%) in the MACRO study. Wild-type (WT) KRAS tumours were found in 219 patients (56%) and mutant (MT) KRAS in 175 patients (44%). Median PFS was 10.9 months for patients with WT KRAS and 9.4 months for patients with MT KRAS tumours (p=0.0038; HR: 1.40; 95% CI:1.12-1.77). The difference in OS was also significant: 26.7 months versus 18.0 months for WT versus MT KRAS, respectively (p=0.0002; HR: 1.55; 95% CI: 1.23-1.96). Univariate and multivariate analyses showed that KRAS was an independent variable for both PFS and OS. Responses were observed in 126 patients (57.5%) with WT KRAS tumours and 76 patients (43.4%) with MT KRAS tumours (p=0.0054; OR: 1.77; 95% CI: 1.18-2.64).

CONCLUSIONS/SIGNIFICANCE

This analysis of the MACRO study suggests a prognostic role for tumour KRAS status in patients with mCRC treated with XELOX plus bevacizumab. For both PFS and OS, KRAS status was an independent factor in univariate and multivariate analyses.

Cytoreductive surgery plus hyperthermic perioperative chemotherapy to treat peritoneal metastases from colorectal cancer: standard of care or an experimental approach?

Peritoneal carcinomatosis is a common presentation in patients with metastatic colorectal cancer and the overall survival is poor. In most patients, the disease remains limited to the peritoneal cavity. Therefore, investigators have applied cytoreductive surgery and hyperthermic perioperative chemotherapy as the standard approach for selected patients with peritoneal metastases from colorectal cancer. Overall, very promising long-term survival has been shown in a subset of patients with a limited extent of peritoneal disease before treatment. Whether randomised, controlled trials are needed to definitively show the magnitude of benefit, if any, of this approach is an important question. This Debate outlines the arguments on each side of this issue.

S-1 plus oxaliplatin versus capecitabine plus oxaliplatin for first-line treatment of patients with metastatic colorectal cancer: a randomised, non-inferiority phase 3 trial

BACKGROUND

Capecitabine plus oxaliplatin (CapeOX) is one of the reference doublet cytotoxic chemotherapy treatments for patients with metastatic colorectal cancer. We aimed to compare the efficacy and safety of CapeOX with that of S-1 plus oxaliplatin (SOX), a promising alternative treatment for patients with metastatic colorectal cancer.

METHODS

In this open-label, multicentre, randomised phase 3 trial, we randomly assigned patients (1:1) from 11 institutions in South Korea to receive either CapeOX (capecitabine 1000 mg/m(2) twice daily on days 1-14 and oxaliplatin 130 mg/m(2) on day 1) or SOX (S-1 40 mg/m(2) twice daily on days 1-14 and oxaliplatin 130 mg/m(2) on day 1). Treatment was repeated every 3 weeks and continued for as many as nine cycles of oxaliplatin-containing chemotherapy, except in instances of disease progression, unacceptable toxicity, or a patient's refusal. Maintenance chemotherapy with S-1 or capecitabine was allowed after discontinuation of oxaliplatin. Randomisation was done with a computer-generated sequence (stratified by primary sites, previous adjuvant or neoadjuvant treatment, and the presence of measurable lesions). The primary endpoint was to show non-inferiority of SOX relative to CapeOX in terms of progression-free survival (PFS). The primary analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00677443.

FINDINGS

Between May 14, 2008, and Sept 23, 2009, we randomly assigned 168 patients to receive SOX and 172 to receive CapeOX. Median PFS was 8·5 months (95% CI 7·6-9·3) in the SOX group and 6·7 months (6·2-7·1) in the CapeOX group (hazard ratio, 0·79 [95% CI 0·60-1·04]; p(non-inferiority)<0·0001, p(log-rank)=0·09). The upper limit of the CI was below the predefined margin of 1·43, showing the non-inferiority of SOX to CapeOX. We recorded a higher incidence of grade 3-4 neutropenia (49 [29%] vs 24 [15%]), thrombocytopenia (37 [22%] vs 11 [7%]), and diarrhoea (16 [10%] vs seven [4%]) in the SOX group than in the CapeOX group. The frequency of any grade of hand-foot syndrome was greater in the CapeOX group than it was in the SOX group (51 [31%] vs 23 [14%]).

INTERPRETATION

The SOX regimen could be an alternative first-line doublet chemotherapy strategy for patients with metastatic colorectal cancer. Further investigation is needed to explore its potential when used together with other targeted agents or as adjuvant chemotherapy.

FUNDING

Korea Healthcare Technology Research and Development Project, Ministry of Health and Welfare, South Korea.

The prognostic value of BRAF mutation in colorectal cancer and melanoma: a systematic review and meta-analysis

BACKGROUND

Mutation of BRAF is a predominant event in cancers with poor prognosis such as melanoma and colorectal cancer. BRAF mutation leads to a constitutive activation of mitogen activated protein kinase pathway which is essential for cell proliferation and tumor progression. Despite tremendous efforts made to target BRAF for cancer treatment, the correlation between BRAF mutation and patient survival is still a matter of controversy.

METHODS/PRINCIPAL FINDINGS

Clinical studies on the correlation between BRAF mutation and patient survival were retrieved from MEDLINE and EMBASE databases between June 2002 and December 2011. One hundred twenty relevant full text studies were categorized based on study design and cancer type. Publication bias was evaluated for each category and pooled hazard ratio (HR) with 95% confidence interval (CI) was calculated using random or fixed effect meta-analysis based on the percentage of heterogeneity. Twenty six studies on colorectal cancer (11,773 patients) and four studies on melanoma (674 patients) were included in our final meta-analysis. The average prevalence of BRAF mutation was 9.6% in colorectal cancer, and 47.8% in melanoma reports. We found that BRAF mutation increases the risk of mortality in colorectal cancer patients for more than two times; HR = 2.25 (95% CI, 1.82-2.83). In addition, we revealed that BRAF mutation also increases the risk of mortality in melanoma patients by 1.7 times (95% CI, 1.37-2.12).

CONCLUSIONS

We revealed that BRAF mutation is an absolute risk factor for patient survival in colorectal cancer and melanoma.

KRAS mutation testing in metastatic colorectal cancer

The KRAS oncogene is mutated in approximately 35%-45% of colorectal cancers, and KRAS mutational status testing has been highlighted in recent years. The most frequent mutations in this gene, point substitutions in codons 12 and 13, were validated as negative predictors of response to anti-epidermal growth factor receptor antibodies. Therefore, determining the KRAS mutational status of tumor samples has become an essential tool for managing patients with colorectal cancers. Currently, a variety of detection methods have been established to analyze the mutation status in the key regions of the KRAS gene; however, several challenges remain related to standardized and uniform testing, including the selection of tumor samples, tumor sample processing and optimal testing methods. Moreover, new testing strategies, in combination with the mutation analysis of BRAF, PIK3CA and loss of PTEN proposed by many researchers and pathologists, should be promoted. In addition, we recommend that microsatellite instability, a prognostic factor, be added to the abovementioned concomitant analysis. This review provides an overview of KRAS biology and the recent advances in KRAS mutation testing. This review also addresses other aspects of status testing for determining the appropriate treatment and offers insight into the potential drawbacks of mutational testing.

Validation of companion diagnostic for detection of mutations in codons 12 and 13 of the KRAS gene in patients with metastatic colorectal cancer: analysis of the NCIC CTG CO.17 trial

CONTEXT

The therascreen KRAS RGQ polymerase chain reaction kit is being developed as a companion diagnostic to aid clinicians, through detection of KRAS mutations, in the identification of patients with metastatic colorectal cancer (mCRC) who are more likely to benefit from cetuximab.

OBJECTIVES

To assess whether KRAS mutation status, determined by using the therascreen KRAS kit, is a predictive marker of cetuximab efficacy.

DESIGN

Tissue samples were obtained from patients with mCRC treated on the National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) CO.17 phase 3 study of cetuximab plus best supportive care (BSC) versus BSC alone. Tumor DNA samples were assessed for the presence of KRAS mutations by using the therascreen KRAS kit. Efficacy and safety were assessed to determine whether mutation status was predictive of outcomes. Results.-Evaluable samples were available from 453 patients (79.2%) enrolled in the NCIC CTG CO.17 trial. The KRAS wild-type subset represented 54.1% (245 of 453) of the evaluated population. Median overall survival of patients with KRAS wild-type tumors was 8.6 months among those who received cetuximab plus BSC and 5.0 months among patients who received BSC alone (hazard ratio [HR], 0.63; P = .002). Among patients with KRAS mutant mCRC, no meaningful difference in overall survival was observed between arms (HR, 0.91; P = .55). These results are consistent with a previous report that analyzed patient tumor samples by using bidirectional sequencing.

CONCLUSIONS

These data support the utility of the therascreen KRAS kit as a means of selecting patients who may benefit from cetuximab therapy.

ESMO Consensus Guidelines for management of patients with colon and rectal cancer. a personalized approach to clinical decision making

Colorectal cancer (CRC) is the most common tumour type in both sexes combined in Western countries. Although screening programmes including the implementation of faecal occult blood test and colonoscopy might be able to reduce mortality by removing precursor lesions and by making diagnosis at an earlier stage, the burden of disease and mortality is still high. Improvement of diagnostic and treatment options increased staging accuracy, functional outcome for early stages as well as survival. Although high quality surgery is still the mainstay of curative treatment, the management of CRC must be a multi-modal approach performed by an experienced multi-disciplinary expert team. Optimal choice of the individual treatment modality according to disease localization and extent, tumour biology and patient factors is able to maintain quality of life, enables long-term survival and even cure in selected patients by a combination of chemotherapy and surgery. Treatment decisions must be based on the available evidence, which has been the basis for this consensus conference-based guideline delivering a clear proposal for diagnostic and treatment measures in each stage of rectal and colon cancer and the individual clinical situations. This ESMO guideline is recommended to be used as the basis for treatment and management decisions.

Predictors of EGF receptor monoclonal antibody activity in metastatic colorectal cancer: current status

SUMMARY In the treatment of metastatic colorectal cancer, the cytostatic drugs 5-fluorouracil, irinotecan and oxaliplatin, as well as the VEGF antibody bevacizumab, are applied without the use of predictive biomarkers. To date, KRAS mutational status is the only accepted predictive biomarker, limiting the use of the EGF receptor (EGFR) monoclonal antibodies cetuximab and panitumumab to patients with KRAS wild-type tumors. The different KRAS mutations on codons 12 and 13 represent a negative predictive biomarker with poor positive predictive power. The negative predictive value of KRAS mutations has been questioned by several retrospective analyses of clinical trials, hypothesizing variable efficacies of EGFR antibodies associated with the diverse range of mutations. While the BRAF mutation is associated with a negative prognosis, its predictive value in the context of EGFR monoclonal antibody therapy is not fully understood. The present review aims to outline possible clinical and molecular biomarkers of EGFR monoclonal antibodies in metastatic colorectal cancer.

Effect of neoadjuvant cetuximab, capecitabine, and radiotherapy for locally advanced rectal cancer: results of a phase II study

PURPOSE

The aim of this study was to investigate the efficacy and safety of neoadjuvant cetuximab, capecitabine, and radiotherapy for patients with locally advanced rectal cancer.

METHODS

Sixty-three eligible patients were selectively enrolled in this study. Neoadjuvant treatment consisted of cetuximab and capecitabine for 6 weeks and radiotherapy for 5 weeks. Surgical resection was performed 6-8 weeks after the completion of neoadjuvant treatment. KRAS mutation statuses were analyzed retrospectively after the cetuximab treatment. All the patients underwent a standardized postoperative follow-up for at least 3 years.

RESULTS

A pathological complete response (pCR) was achieved in eight patients (12.7 %). Overall down-staging was found in 49 patients (77.8 %). The 3-year disease-free survival (DFS) rate and overall survival (OS) rate was 76.2 % and 81.0 %, respectively. The most common adverse events during neoadjuvant treatment were acneiform skin rash (82.5 %), radiodermatitis (46.0 %), and diarrhea (36.5 %). KRAS mutations were detected in 19 of 63 (31.2 %) tumors. The down-staging rate in patients with KRAS wild-type (WT) was significantly higher than patients with KRAS mutation (P = 0.020). There was no significant difference in the pCR rate, 3-year DFS rate or 3-year OS rate between KRAS WT patients and KRAS-mutated patients.

CONCLUSION

Neoadjuvant treatment with cetuximab and capecitabine-based chemoradiotherapy is safe and well tolerated. The pCR rate, 3-year DFS rate and OS rate are not superior to the rate of neoadjuvant chemoradiotherapy using two or more cytotoxic agents. The KRAS WT is highly associated with tumor down-staging to cetuximab plus capecitabine-based CRT in patients with LARC.

Clinical Implementation of KRAS Testing in Metastatic Colorectal Carcinoma: The Pathologist's Perspective

Context.—Mutation status of the KRAS gene identifies a distinct disease subtype of metastatic colorectal carcinoma that does not respond to antibody therapeutics targeting the epidermal growth factor receptor. This is currently the only validated marker in metastatic colorectal carcinoma with a clear implication in treatment selection. KRAS testing is widely accepted in clinical practice to guide metastatic colorectal carcinoma therapeutic decisions, and there are many commercially available platforms to perform the test.

Objective.—To evaluate the critical role of pathologists in the full implementation of KRAS testing by optimizing tumor tissue collection and fixation procedures and by choosing testing technologies and reliable Clinical Laboratory Improvement Amendments of 1988–certified laboratories to perform the tests.

Data Sources.—Prospective clinical trials, retrospective studies, and quality assessment and survey reports were identified in the following databases: PubMed, American Society of Clinical Oncology Proceedings (American Society of Clinical Oncology Annual Meeting and Gastrointestinal Cancer Symposium) and European Society for Medical Oncology Proceedings (Annals of Oncology European Society for Medical Oncology Congress and Annals of Oncology World Congress on Gastrointestinal Cancers).

Conclusions.—More bona fide standards are needed to address the variety of available test methods, which have different performance characteristics including speed, sensitivity to detect rare mutations, and technical requirements. Refined standards addressing timing of KRAS testing, laboratory performance and accuracy, quality assurance and control, proper tissue collection, and appropriate result reporting would also be greatly beneficial. Pathologists should be aware that the amount of information they need to manage will increase, because future trends and technological advances will enhance the predictive power of diagnostic tests or the scope of the biomarker panels tested routinely across tumor types.

Cetuximab in metastatic colorectal cancer

Management of metastatic colorectal cancer has evolved in the last 10 years, with the availability of targeted therapies resulting in improvement in quality of life and overall survival. Cetuximab is a chimeric monoclonal antibody that binds to the EGF receptor, and the net effects are inhibition of tumor growth, invasion, angiogenesis and metastasis. Cetuximab binding to the EGF receptor is also known to augment the effects of chemotherapy and radiotherapy. Only tumors expressing wild-type KRAS respond to cetuximab and improvements in progression-free survival and overall survival are seen, whereas patients with mutant KRAS are considered to be resistant. Cetuximab is currently available worldwide for use as monotherapy or in combination with chemotherapy in first-, second- or third-line settings in metastatic colorectal cancer patients with wild-type KRAS.

Prognostic and predictive roles of KRAS mutation in colorectal cancer

The RAS gene family is among the most studied and best characterized of the known cancer-related genes. Of the three human ras isoforms, KRAS is the most frequently altered gene, with mutations occurring in 17%-25% of all cancers. In particular, approximately 30%-40% of colon cancers harbor a KRAS mutation. KRAS mutations in colon cancers have been associated with poorer survival and increased tumor aggressiveness. Additionally, KRAS mutations in colorectal cancer lead to resistance to select treatment strategies. In this review we examine the history of KRAS, its prognostic value in patients with colorectal cancer, and evidence supporting its predictive value in determining appropriate therapies for patients with colorectal cancer.

Systematic review of laser and other light therapy for the management of oral mucositis in cancer patients

BACKGROUND

The aim of this study was to review the available literature and define clinical practice guidelines for the use of laser and other light therapies for the prevention and treatment of oral mucositis.

METHODS

A systematic review was conducted by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology. The body of evidence for each intervention, in each cancer treatment setting, was assigned an evidence level. Based on the evidence level, one of the following three guideline determinations was possible: recommendation, suggestion, and no guideline possible.

RESULTS

A new recommendation was made for low-level laser (wavelength at 650 nm, power of 40 mW, and each square centimeter treated with the required time to a tissue energy dose of 2 J/cm(2) (2 s/point)) for the prevention of oral mucositis in adult patients receiving hematopoietic stem cell transplantation conditioned with high-dose chemotherapy, with or without total body irradiation. A new suggestion was made for low-level laser (wavelength around 632.8 nm) for the prevention of oral mucositis in patients undergoing radiotherapy, without concomitant chemotherapy, for head and neck cancer. No guideline was possible in other populations and for other light sources due to insufficient evidence.

CONCLUSIONS

The increasing evidence in favor of low-level laser therapy allowed for the development of two new guidelines supporting this modality in the populations listed above. Evidence for other populations was also generally encouraging over a range of wavelengths and intensities. However, additional well-designed research is needed to evaluate the efficacy of laser and other light therapies in various cancer treatment settings.

The promise of mTOR inhibitors in the treatment of colorectal cancer

INTRODUCTION

Recently, deregulation of protein synthesis has begun to gain attention as a major player in cancer development and progression. Specifically, deregulation of the process of translation initiation appears to play a key role in oncogenesis. The PI3K/Akt/mTOR pathway is vital for cellular metabolism, growth and proliferation and thus an attractive therapeutic target in oncology. Accordingly, several mTOR inhibitors are currently being tested in many cancers including colorectal cancer (CRC).

AREAS COVERED

In this review, the key components of the PI3K/Akt/mTOR pathways, their molecular alterations and the inhibitors targeting the mTOR pathway in CRC are described. Complex interactions with other pathways such as the MAPK pathway are analyzed, as are possible drug combinations that target this pathway. In addition, novel strategies for use of mTOR pathway inhibitors in CRC treatment are introduced.

EXPERT OPINION

Clinical trials of mTOR inhibitors have been investigated in CRC. mTOR inhibitors may represent an attractive antitumor target in combination with strategies to target other pathways that may overcome resistance. Further research is needed to identify critical molecular effector mechanisms, molecular markers that predict responsiveness and potential toxicities.

Guidance for life, cell death, and colorectal neoplasia by netrin dependence receptors

This review is focusing on a critical mediator of embryonic and postnatal development with multiple implications in inflammation, neoplasia, and other pathological situations in brain and peripheral tissues. These morphogenetic guidance and dependence processes are involved in several malignancies targeting the epithelial and immune systems including the progression of human colorectal cancers. We consider the most important findings and their impact on basic, translational, and clinical cancer research. Expected information can bring new cues for innovative, efficient, and safe strategies of personalized medicine based on molecular markers, protagonists, signaling networks, and effectors inherent to the Netrin axis in pathophysiological states.

The oncosurgery approach to managing liver metastases from colorectal cancer: a multidisciplinary international consensus

An international panel of multidisciplinary experts convened to develop recommendations for the management of patients with liver metastases from colorectal cancer (CRC). The aim was to address the main issues facing the CRC hepatobiliary multidisciplinary team (MDT) when managing such patients and to standardize the treatment patients receive in different centers. Based on current evidence, the group agreed on a number of issues including the following: (a) the primary aim of treatment is achieving a long disease-free survival (DFS) interval following resection; (b) assessment of resectability should be performed with high-quality cross-sectional imaging, staging the liver with magnetic resonance imaging and/or abdominal computed tomography (CT), depending on local expertise, staging extrahepatic disease with thoracic and pelvic CT, and, in selected cases, fluorodeoxyglucose positron emission tomography with ultrasound (preferably contrast-enhanced ultrasound) for intraoperative staging; (c) optimal first-line chemotherapy-doublet or triplet chemotherapy regimens combined with targeted therapy-is advisable in potentially resectable patients; (d) in this situation, at least four courses of first-line chemotherapy should be given, with assessment of tumor response every 2 months; (e) response assessed by the Response Evaluation Criteria in Solid Tumors (conventional chemotherapy) or nonsize-based morphological changes (antiangiogenic agents) is clearly correlated with outcome; no imaging technique is currently able to accurately diagnose complete pathological response but high-quality imaging is crucial for patient management; (f) the duration of chemotherapy should be as short as possible and resection achieved as soon as technically possible in the absence of tumor progression; (g) the number of metastases or patient age should not be an absolute contraindication to surgery combined with chemotherapy; (h) for synchronous metastases, it is not advisable to undertake major hepatic surgery during surgery for removal of the primary CRC; the reverse surgical approach (liver first) produces as good an outcome as the conventional approach in selected cases; (i) for patients with resectable liver metastases from CRC, perioperative chemotherapy may be associated with a modestly better DFS outcome; and (j) whether initially resectable or unresectable, cure or at least a long survival duration is possible after complete resection of the metastases, and MDT treatment is essential for improving clinical and survival outcomes. The group proposed a new system to classify initial unresectability based on technical and oncological contraindications.

Specific mutations in KRAS codons 12 and 13, and patient prognosis in 1075 BRAF wild-type colorectal cancers

PURPOSE

To assess prognostic roles of various KRAS oncogene mutations in colorectal cancer, BRAF mutation status must be controlled for because BRAF mutation is associated with poor prognosis, and almost all BRAF mutants are present among KRAS wild-type tumors. Taking into account experimental data supporting a greater oncogenic effect of codon 12 mutations compared with codon 13 mutations, we hypothesized that KRAS codon 12-mutated colorectal cancers might behave more aggressively than KRAS wild-type tumors and codon 13 mutants.

EXPERIMENTAL DESIGN

Using molecular pathological epidemiology database of 1,261 rectal and colon cancers, we examined clinical outcome and tumor biomarkers of KRAS codon 12 and 13 mutations in 1,075 BRAF wild-type cancers (i.e., controlling for BRAF status). Cox proportional hazards model was used to compute mortality HR, adjusting for potential confounders, including stage, PIK3CA mutations, microsatellite instability, CpG island methylator phenotype, and LINE-1 methylation.

RESULTS

Compared with patients with KRAS wild-type/BRAF wild-type cancers (N = 635), those with KRAS codon 12 mutations (N = 332) experienced significantly higher colorectal cancer-specific mortality [log-rank P = 0.0001; multivariate HR, 1.30; 95% confidence interval (CI), 1.02-1.67; P = 0.037], whereas KRAS codon 13-mutated cases (N = 108) were not significantly associated with prognosis. Among the seven most common KRAS mutations, c.35G>T (p.G12V; N = 93) was associated with significantly higher colorectal cancer-specific mortality (log-rank P = 0.0007; multivariate HR, 2.00; 95% CI, 1.38-2.90, P = 0.0003) compared with KRAS wild-type/BRAF wild-type cases.

CONCLUSIONS

KRAS codon 12 mutations (in particular, c.35G>T), but not codon 13 mutations, are associated with inferior survival in BRAF wild-type colorectal cancer. Our data highlight the importance of accurate molecular characterization in colorectal cancer.