Impact of KRAS, BRAF and PI3KCA mutations in rectal carcinomas treated with neoadjuvant radiochemotherapy and surgery

BACKGROUND

Conventional treatment for locally advanced rectal cancer usually combines neoadjuvant radiochemotherapy and surgery. Until recently, there have been limited predictive factors (clinical or biological) for rectal tumor response to conventional treatment. KRAS, BRAF and PIK3CA mutations are commonly found in colon cancers. In this study, we aimed to determine the mutation frequencies of KRAS, BRAF and PIK3CA and to establish whether such mutations may be used as prognostic and/or predictive factors in rectal cancer patients.

METHODS

We retrospectively reviewed the clinical and biological data of 98 consecutive operated patients between May 2006 and September 2009. We focused in patients who received surgery in our center after radiochemotherapy and in which tumor samples were available.

RESULTS

In the 98 patients with a rectal cancer, the median follow-up time was 28.3 months (4-74). Eight out of ninety-eight patients experienced a local recurrence (8%) and 17/98 developed distant metastasis (17%). KRAS, BRAF and PIK3CA were identified respectively in 23 (23.5%), 2 (2%) and 4 (4%) patients. As described in previous studies, mutations in KRAS and BRAF were mutually exclusive. No patient with local recurrence exhibited KRAS or PIK3CA mutation and one harbored BRAF mutation (12.5%). Of the seventeen patients with distant metastasis (17%), 5 were presenting KRAS mutation (29%), one BRAF (5%) and one PIK3CA mutation (5%). No relationship was seen between PIK3CA, KRAS or BRAF mutation and local or distant recurrences.

CONCLUSION

The frequencies of KRAS, BRAF and PIK3CA mutations in our study were lower than the average frequencies reported in colorectal cancers and no significant correlation was found between local/distant recurrences and KRAS, BRAF or PIK3CA mutations. Future studies with greater number of patients, longer follow-up time and greater power to predict associations are necessary to fully understand this relationship.

Special AT-rich sequence-binding protein 1 promotes cell growth and metastasis in colorectal cancer

AIM: To evaluate the expression of special AT-rich sequence-binding protein 1 (SATB1) gene in colorectal cancer and its role in colorectal cancer cell proliferation and invasion.

METHODS: Immunohistochemistry was used to detect the protein expression of SATB1 in 30 colorectal cancer (CRC) tissue samples and pair-matched adjacent non-tumor samples. Cell growth was investigated after enhancing expression of SATB1. Wound-healing assay and Transwell assay were used to investigate the impact of SATB1 on migratory and invasive abilities of SW480 cells in vitro. Nude mice that received subcutaneous implantation or lateral tail vein were used to study the effects of SATB1 on tumor growth or metastasis in vivo.

RESULTS: SATB1 was over-expressed in CRC tissues and CRC cell lines. SATB1 promotes cell proliferation and cell cycle progression in CRC SW480 cells. SATB1 overexpression could promote cell growth in vivo. In addition, SATB1 could significantly raise the ability of cell migration and invasion in vitro and promote the ability of tumor metastasis in vivo. SATB1 could up-regulate matrix metalloproteases 2, 9, cyclin D1 and vimentin, meanwhile SATB1 could down-regulate E-cadherin in CRC.

CONCLUSION: SATB1 acts as a potential growth and metastasis promoter in CRC. SATB1 may be useful as a therapeutic target for CRC.

Fool's gold, lost treasures, and the randomized clinical trial

Background

Randomized controlled trials with a survival endpoint are the gold standard for clinical research, but have failed to achieve cures for most advanced malignancies. The high costs of randomized clinical trials slow progress (thereby causing avoidable loss of life) and increase health care costs.

Discussion

A malignancy may be caused by several different mutations. Therapies effective vs one mutation may be discarded due to lack of statistical significance across the entire population. Conversely, expensive large randomized trials may have sufficient statistical power to demonstrate benefit despite the therapy only working in subgroups. Non-cost-effective therapy is then applied to all patients (including subgroups it cannot help). Randomized trials comparing therapies with different mechanisms of action are misleading since they may conclude the therapies are “equivalent” despite benefitting different subpopulations, or may erroneously conclude that one therapy is superior simply because it targets a larger subpopulation. Furthermore, minor variances in patient selection may determine study outcome, a therapy may be discarded as ineffective despite substantial benefit in one subpopulation if harmful in another, randomized trials may more effectively detect therapies with minor benefit in most patients vs marked benefit in subpopulations, and randomized trials in unselected patients may erroneously conclude that “shot-gun” combinations are superior to single agents when sequential administration of personalized single agents might work better and spare patients treatment with drugs that cannot help them. We must identify predictive biomarkers early by comparing responding to progressing patients in phase I-II trials. Enriching randomized trials for biomarker-positive patients can markedly reduce required patient numbers and costs despite expensive screening for biomarker-positive patients. Available data support approval of new drugs without randomized trials if they yield single-agent sustained responses in patients refractory to standard therapies. Conversely, new approaches are needed to guide development of drug combinations since both standard phase II approaches and phase II-III randomized trials have a high risk of misleading.

Summary

Traditional randomized clinical trials approaches are often inefficient, wasteful, and unreliable. New clinical research paradigms are needed. The primary outcome of clinical research should be “Who (if anyone) benefits?” rather than “Does the overall group benefit?”

Phase II trial of preoperative radiochemotherapy with concurrent bevacizumab, capecitabine and oxaliplatin in patients with locally advanced rectal cancer

BACKGROUND

Preoperative radiochemotherapy (RCT) with 5-FU or capecitabine is the standard of care for patients with locally advanced rectal cancer (LARC). Preoperative RCT achieves pathological complete response rates (pCR) of 10-15%. We conducted a single arm phase II study to investigate the feasibility and efficacy of addition of bevacizumab and oxaliplatin to preoperative standard RCT with capecitabine.

METHODS

Eligible patients had LARC (cT3-4; N0/1/2, M0/1) and were treated with preoperative RCT prior to planned surgery. Patients received conventionally fractionated radiotherapy (50.4 Gy in 1.8 Gy fractions) and simultaneous chemotherapy with capecitabine 825 mg/m2 bid (d1-14, d22-35) and oxaliplatin 50 mg/m2 (d1, d8, d22, d29). Bevacizumab 5 mg/kg was added on days 1, 15, and 29. The primary study objective was the pCR rate.

RESULTS

70 patients with LARC (cT3-4; N0/1, M0/1), ECOG < 2, were enrolled at 6 sites from 07/2008 through 02/2010 (median age 61 years [range 39-89], 68% male). At initial diagnosis, 84% of patients had clinical stage T3, 62% of patients had nodal involvement and 83% of patients were M0. Mean tumor distance from anal verge was 5.92 cm (± 3.68). 58 patients received the complete RCT (full dose RT and full dose of all chemotherapy). During preoperative treatment, grade 3 or 4 toxicities were experienced by 6 and 2 patients, respectively: grade 4 diarrhea and nausea in one patient (1.4%), respectively, grade 3 diarrhea in 2 patients (3%), grade 3 obstipation, anal abscess, anaphylactic reaction, leucopenia and neutropenia in one patient (1.4%), respectively. In total, 30 patients (46%) developed postoperative complications of any grade including one gastrointestinal perforation in one patient (2%), wound-healing problems in 7 patients (11%) and bleedings in 2 patients (3%). pCR was observed in 12/69 (17.4%) patients. Pathological downstaging (ypT < cT and ypN ≤ cN) was achieved in 31 of 69 patients (44.9%). All of the 66 operated patients had a R0 resection. 47 patients (68.1%) underwent sphincter preserving surgery.

CONCLUSIONS

The addition of bevacizumab and oxaliplatin to RCT with capecitabine was well tolerated and did not increase perioperative morbidity or mortality. However, the pCR rate was not improved in comparison to other trials that used capecitabine or capecitabine/oxaliplatin in preoperative radiochemotherapy.

Personalizing oncology: perspectives and prospects

This article provides an overview of the research, beginning a century ago, that has led to the current use of genomically informed methods for selection of targeted therapies to treat individual patients with cancer--so-called precision cancer medicine. Until 1980, most research on cancer therapy was not targeted in the sense we use the word today. Since then, there has been an acceleration in research identifying genetic and molecular targets and in clinical trials using biomarkers that identify the presence of genetic or molecular markers in a patient's cancer to select appropriate targeted therapy. This approach has been made possible by increased knowledge of the genetic pathogenesis of cancer and by increased capacity to sequence genes and genomes in clinically useful timeframes and at a reasonable cost. However, many challenges and pitfalls remain in selecting optimal targets, interpreting data on genetic aberrations, designing effective targeted drugs and antibodies, dealing with resistance to treatments, identifying appropriate combinations of therapies, and performing the complex clinical trials that are required. Future clinical research with experimental targeted agents is likely to be more informative because of appropriate preselection of patients enrolled onto trials and performance of genetic and molecular studies on specimens of a patient's cancer before and after treatment.

Capecitabine and cisplatin with or without cetuximab for patients with previously untreated advanced gastric cancer (EXPAND): a randomised, open-label phase 3 trial

BACKGROUND

Patients with advanced gastric cancer have a poor prognosis and few efficacious treatment options. We aimed to assess the addition of cetuximab to capecitabine-cisplatin chemotherapy in patients with advanced gastric or gastro-oesophageal junction cancer.

METHODS

In our open-label, randomised phase 3 trial (EXPAND), we enrolled adults aged 18 years or older with histologically confirmed locally advanced unresectable (M0) or metastatic (M1) adenocarcinoma of the stomach or gastro-oesophageal junction. We enrolled patients at 164 sites (teaching hospitals and clinics) in 25 countries, and randomly assigned eligible participants (1:1) to receive first-line chemotherapy with or without cetuximab. Randomisation was done with a permuted block randomisation procedure (variable block size), stratified by disease stage (M0 vs M1), previous oesophagectomy or gastrectomy (yes vs no), and previous (neo)adjuvant (radio)chemotherapy (yes vs no). Treatment consisted of 3-week cycles of twice-daily capecitabine 1000 mg/m(2) (on days 1-14) and intravenous cisplatin 80 mg/m(2) (on day 1), with or without weekly cetuximab (400 mg/m(2) initial infusion on day 1 followed by 250 mg/m(2) per week thereafter). The primary endpoint was progression-free survival (PFS), assessed by a masked independent review committee in the intention-to-treat population. We assessed safety in all patients who received at least one dose of study drug. This study is registered at EudraCT, number 2007-004219-75.

FINDINGS

Between June 30, 2008, and Dec 15, 2010, we enrolled 904 patients. Median PFS for 455 patients allocated capecitabine-cisplatin plus cetuximab was 4.4 months (95% CI 4.2-5.5) compared with 5.6 months (5.1-5.7) for 449 patients who were allocated to receive capecitabine-cisplatin alone (hazard ratio 1.09, 95% CI 0.92-1.29; p=0.32). 369 (83%) of 446 patients in the chemotherapy plus cetuximab group and 337 (77%) of 436 patients in the chemotherapy group had grade 3-4 adverse events, including grade 3-4 diarrhoea, hypokalaemia, hypomagnesaemia, rash, and hand-foot syndrome. Grade 3-4 neutropenia was more common in controls than in patients who received cetuximab. Incidence of grade 3-4 skin reactions and acne-like rash was substantially higher in the cetuximab-containing regimen than in the control regimen. 239 (54%) of 446 in the cetuximab group and 194 (44%) of 436 in the control group had any grade of serious adverse event.

INTERPRETATION

Addition of cetuximab to capecitabine-cisplatin provided no additional benefit to chemotherapy alone in the first-line treatment of advanced gastric cancer in our trial.

FUNDING

Merck KGaA.

The importance of molecular profiling in predicting response to epidermal growth factor receptor family inhibitors in non-small-cell lung cancer: focus on clinical trial results

In recent years, the epidermal growth factor receptor (EGFR) family has become a key focus of non-small-cell lung cancer biology and targeted therapies, such as the reversible EGFR tyrosine kinase inhibitors erlotinib and gefitinib. Initially, response to these agents was associated with certain demographic and clinical characteristics; subsequently, it was discovered that these subgroups were more likely to harbor specific mutations in the EGFR gene that enhanced tumor response. However, the presence of these mutations does not equate to therapeutic success. Other aspects of EGFR family signaling, including other types of EGFR mutations, EGFR protein expression, EGFR gene amplification, mediators of downstream signaling, and other receptors with similar downstream pathways may all play a role in response or resistance to treatment. The identification of these and other molecular determinants is driving the development of novel therapies designed to achieve improved clinical outcomes in patients.

A patient-derived somatic mutation in the epidermal growth factor receptor ligand-binding domain confers increased sensitivity to cetuximab in head and neck cancer

BACKGROUND

Cetuximab is an epidermal growth factor receptor (EGFR)-blocking antibody that has been approved for the treatment of patients with head and neck squamous cell carcinoma (HNSCC) and metastatic colorectal cancer, but no predictive biomarkers of activity have been yet identified. Establishment of such biomarkers will help identify a subset of patients that will benefit from cetuximab therapy.

METHODS

In this paper, we report on a patient with HNSCC who had a complete tumour regression following treatment with cetuximab given as a single agent after initial surgery and radiation therapy. The EGFR protein expression level, the EGFR gene copy number and the EGFR gene sequence were assessed from both normal and tumour tissues.

RESULTS

Besides protein overexpression and gene amplification in the tumour tissue, sequencing of the EGFR gene from the patient revealed the presence of two somatic mutations, one in the kinase domain (R705G) and the other in the ligand binding domain (P546S). Cells that stably express these EGFR mutants were treated with cetuximab and their sensitivity to the drug was compared to cells expressing the wildtype gene. While P546S mutation sensitised NIH-3T3 cells to cetuximab, R705G had a marginal effect. The double mutant (P546S/R705G) behaved like the P546S mutant, indicating that the mutation in the kinase domain does not contribute to the increased sensitivity to cetuximab. No mutations were found in K-RAS or B-RAF genes and no HPV protein or DNA was detected in the tumour. This is the first report of a somatic mutation in the EGFR ligand binding domain that may contribute to increased sensitivity to cetuximab.

CONCLUSIONS

Our results support a role for the P546S mutation in cetuximab sensitivity. Other factors including EGFR protein high copy number and protein overexpression may have also contributed to the observed response. The severity of a skin rash developed by this patient and its correlation with the antitumour activity does not exclude the involvement of the immune system (i.e. complement-mediated immune response) as well. The occurrence of the P546S mutation needs to be evaluated in HNSCC, as a well as a prospective evaluation of cetuximab anti-tumour activity in patients with tumours harbouring the mutation.

Surgical outcomes after resection of both hepatic and pulmonary metastases from colorectal cancer

BACKGROUND

The efficacy and the indications of resection of synchronous or metachronous hepatic and pulmonary metastases from colorectal cancer (CRC) are controversial. This study retrospectively reviewed the cases of CRC patients who underwent both liver and lung resection to define the appropriate indications for surgical resection in patients with hepatic and pulmonary metastases.

METHODS

A total of 39 patients with both hepatic and pulmonary metastases from CRC underwent both liver and lung resection from January 1987 to December 2009. The relapse-free survival (RFS) and overall survival (OS) from the resection for the first metastasis were evaluated by a Kaplan-Meyer analysis. Prognostic factors were analyzed using the log-rank test and a Cox proportional hazards model.

RESULTS

The median RFS and the 5-year RFS rate of all patients were 12 months and 2.6 %, respectively. The median survival time (MST) and 5-year OS rate of all patients were 66 months and 48.3 %, respectively. The MST of the patients with a long (>1 year) disease-free interval (DFI) could not be calculated, but their 5-year OS rate was 73.7 %. In contrast, the MST and 5-year OS rate of the patients with a short (<1 year) DFI were 29 months and 37.5 %, respectively. The short DFI was the only prognostic factor in the multivariate analysis.

CONCLUSIONS

Aggressive surgical resection of both hepatic and pulmonary metastases from CRC should be undertaken in selective patients, including those with a long DFI.

Management of colon cancer: resource-stratified guidelines from the Asian Oncology Summit 2012

Colon cancer is seen with increasing frequency in the Asia-Pacific region, and it is one of the most important causes of cancer mortality worldwide. This article reviews the available evidence for optimum management of colon cancer-in particular, with respect to screening and early detection of colon cancer, laparoscopic surgical treatment, adjuvant treatment of individuals with high-risk stage II and stage III cancer, palliative treatment of patients with metastatic disease, and management of resectable and potentially resectable metastases-and how these strategies can be applied in Asian countries with different levels of health-care resources and economic development, stratified by basic, limited, enhanced, and maximum resource levels.

Somatic mutations in exocrine pancreatic tumors: association with patient survival

KRAS mutations are major factors involved in initiation and maintenance of pancreatic tumors. The impact of different mutations on patient survival has not been clearly defined. We screened tumors from 171 pancreatic cancer patients for mutations in KRAS and CDKN2A genes. Mutations in KRAS were detected in 134 tumors, with 131 in codon 12 and only 3 in codon 61. The GGT>GAT (G12D) was the most frequent mutation and was present in 60% (80/134). Deletions and mutations in CDKN2A were detected in 43 tumors. Analysis showed that KRAS mutations were associated with reduced patient survival in both malignant exocrine and ductal adenocarcinomas (PDAC). Patients with PDACs that had KRAS mutations showed a median survival of 17 months compared to 30 months for those without mutations (log-rank P = 0.07) with a multivariate hazard ratio (HR) of 2.19 (95%CI 1.09-4.42). The patients with G12D mutation showed a median survival of 16 months (log-rank-test P = 0.03) and an associated multivariate HR 2.42 (95%CI 1.14-2.67). Although, the association of survival in PDAC patients with CDKN2A aberrations in tumors was not statistically significant, the sub-group of patients with concomitant KRAS mutations and CDKN2A alterations in tumors were associated with a median survival of 13.5 months compared to 22 months without mutation (log-rank-test P = 0.02) and a corresponding HR of 3.07 (95%CI 1.33-7.10). Our results are indicative of an association between mutational status and survival in PDAC patients, which if confirmed in subsequent studies can have potential clinical application.

BRAF inhibitors in clinical oncology

Activating mutations of the BRAF oncogene are present in approximately 5-10% of all human malignancies and lead to constitutive activation of the mitogen activated protein kinase (MAPK) pathway. The introduction of BRAF inhibitors has greatly improved the short term prospects of some patients with these tumors, but the tumors tend to become resistant to therapy with time by activating alternative signaling pathways. Consequently, combination strategies with drugs that block not only the primary mutated BRAF kinase but also the alternative pathways implicated in development of resistance may represent a better strategy for improving survival in patients with tumors harboring BRAF mutations.

KRAS mutation status is not predictive for objective response to anti-EGFR treatment with erlotinib in patients with advanced pancreatic cancer

BACKGROUND

It has not yet been defined if KRAS has a prognostic value or is a predictive biomarker for the efficacy of erlotinib in advanced pancreatic cancer (PC).

METHODS

AIO-PK0104 was a phase III trial comparing gemcitabine/erlotinib followed by capecitabine with capecitabine/erlotinib followed by gemcitabine in advanced PC. For this post hoc subgroup analysis, biomarker data on the KRAS exon 2 mutation status were correlated with objective response to 1st-line therapy and with overall survival after start of 2nd-line chemotherapy (OSc).

RESULTS

KRAS codon 12 was mutated in 121 of 173 (70 %) patients. The KRAS status showed no association with objective response (p = 0.40), but KRAS wildtype patients had an improved OS (HR 1.68, p = 0.005). A trend for a survival benefit was also observed during (non-erlotinib containing) 2nd-line chemotherapy, with a HR of 1.47 (p = 0.10) for the OSc.

CONCLUSION

This post hoc analysis of AIO-PK0104 supports the assumption that KRAS is rather a prognostic than a predictive biomarker in PC.

Oxaliplatin for colorectal cancer: recent evidence from clinical trials

SUMMARY Oxaliplatin, a second-generation platinum analog, has evolved as one of the most important therapeutic agents in the treatment of both metastatic colorectal cancer and stage II/III colon cancer. Moreover, oxaliplatin is currently being investigated in the perioperative treatment of locally advanced rectal cancer. Oxaliplatin can be safely combined with fluoropyrimidines, irinotecan, bevacizumab and EGF receptor antibodies, resulting in increased response rates and delayed progression. In combination with EGF receptor antibodies, fluoropyrimidine schedules need to be cautiously considered. Treatment strategies to limit oxaliplatin-induced neurotoxicity by discontinuous administration schedules (e.g., induction followed by maintenance, followed by reinduction or intermittent treatment) are available.

Validation study of a prognostic classification in patients with metastatic colorectal cancer who received irinotecan-based second-line chemotherapy

PURPOSE

Five prognostic factors had been previously identified in patients with metastatic colorectal cancer (MCRC) who received irinotecan-based second-line chemotherapy. Patients were classified into three prognostic groups based on significant differences in median overall survival (OS). This study is conducted to validate this classification in an external validation cohort.

METHODS

This retrospective study included 193 patients of an external validation cohort who received irinotecan-based second-line chemotherapy after first-line oxaliplatin-based chemotherapy, with or without bevacizumab at three institutions.

RESULTS

Three of the five predefined factors (poorly differentiated adenocarcinoma, LDH ≥400 IU/L, progression-free survival of first-line therapy <6 months) remained highly significant in the validation cohort, although two (performance status 2 and peritoneal metastasis) were associated with borderline significance. The distribution of the three prognostic groups (low risk = no factors, intermediate risk = 1 factor, high risk = 2 or more factors) was low risk (n = 68; 35 %), intermediate risk (n = 80; 41 %), and high risk (n = 45; 23 %). The median OS of each group were 19.8, 11.0, and 7.9 months, respectively, with significant differences between groups, as found in the previous cohort.

CONCLUSION

The previous prognostic classification of patients with MCRC who received irinotecan-based second-line chemotherapy was validated in another independent cohort. Validation in prospective studies is warranted.

Prognostic factors in patients with non resectable metastatic colorectal cancer in the era of targeted biotherapies: relevance of Köhne's risk classification

BACKGROUND

Köhne's prognostic classification has been previously proposed, based on performance status, alkaline phosphatase level, number of metastatic sites and white blood cells count.

AIMS

To identify prognostic factors for survival and to assess the validity of Köhne's classification, in the era of targeted biotherapies, in patients treated with chemotherapy for non resectable metastatic colorectal cancer.

METHODS

A total of 290 consecutive patients were retrospectively identified in all gastroenterology units of one French county, between 2004 and 2008. Univariate and multivariate analysis for overall survival were performed using pre-treatment patient characteristics.

RESULTS

All data were available for prognostic categorization in 133 patients. Median survival was 22.1 months. The distribution and median survival for Köhne's prognostic groups were as following: good (n=73; 24.8 months), intermediate (n=35; 24.2 months), and poor (n=25; 7.0 months). The survival difference was significant between good and poor prognostic groups (p<0.01) and between intermediate and poor prognostic groups (p<0.01), but not between good and intermediate prognostic groups (p=0.5). The two independent prognostic factors of survival in multivariate analysis were performance status 0/1 (p<0.01) and white blood cells count<10×10(9)/L (p<0.01).

CONCLUSIONS

The relevance of Köhne's classification is questioned. A simplified score could be validated by largest studies, based on white blood cells count and performance status.

Targeting mechanisms of resistance to anti-EGF receptor therapy in KRAS wild-type colorectal cancer: the path to more personalized medicine

The targeting of EGF receptors (EGFRs) in metastatic colorectal cancer has improved the outcome of patients with KRAS wild-type tumors. However, these improvements have been modest and do not translate across all patients with KRAS wild-type tumors. Better understanding of the EGFR pathway has led to the exploration of variable novel potential biomarkers of resistance and response to anti-EGFR therapy. This manuscript will focus on recently identified mechanisms of resistance to anti-EGFR therapy in KRAS wild-type colorectal cancer. Subsequently, an assessment will be presented on how the current understanding of some of these mechanisms of resistance has led, and will lead, to novel therapeutic opportunities in the management of colorectal cancer.

Rare Though Not Mutually Exclusive: A Report of Three Cases of Concomitant KRAS and BRAF Mutation and a Review of the Literature

KRAS mutations occur frequently in colorectal cancers (CRC) and predict lack of response to anti-epidermal growth factor receptor (EGFR) monoclonal antibody therapy. CRC BRAF mutations, most commonly at V600E, occur less than 10% of the time, and occur usually in KRAS wild-type tumors, and more frequently in microsatellite instable tumors. Concomitant KRAS and BRAF mutant CRCs are rare (occurring in 0.001%); BRAF mutations should not be routinely tested in patients with KRAS mutant tumors, unless the patients is participating in a clinical trial enriching for the presence of a KRAS or BRAF tumor. Clinical trials treating patients with either KRAS or BRAF mutant tumors should address eligibility of patients with concomitant KRAS and BRAF mutations.

Cetuximab: a guide to its use in combination with FOLFIRI in the first-line treatment of metastatic colorectal cancer in the USA

Cetuximab (Erbitux(®)) is a monoclonal antibody that targets the epidermal growth factor receptor (EGFR). In the USA, the approval of cetuximab has been recently expanded to include the first-line treatment of patients with KRAS mutation-negative (wild-type), EGFR-expressing, metastatic colorectal cancer (mCRC) when used in combination with FOLFIRI (irinotecan, fluorouracil, leucovorin [folinic acid]). The addition of cetuximab to first-line treatment with FOLFIRI improved progression-free survival, overall survival, and objective response rates relative to treatment with FOLFIRI alone in patients with EGFR-expressing mCRC with KRAS wild-type tumors. Therefore, cetuximab plus FOLFIRI is a useful biomarker-directed option in the first-line treatment of this patient population.

Sorafenib in combination with oxaliplatin, leucovorin, and fluorouracil (modified FOLFOX6) as first-line treatment of metastatic colorectal cancer: the RESPECT trial

PURPOSE

This randomized, double-blind, placebo-controlled, phase IIb study evaluated adding sorafenib to first-line modified FOLFOX6 (mFOLFOX6) for metastatic colorectal cancer (mCRC).

EXPERIMENTAL DESIGN

Patients were randomized to sorafenib (400 mg b.i.d.) or placebo, combined with mFOLFOX6 (oxaliplatin 85 mg/m(2); levo-leucovorin 200 mg/m(2); fluorouracil 400 mg/m(2) bolus and 2400 mg/m(2) continuous infusion) every 14 days. Primary endpoint was progression-free survival (PFS). Target sample was 120 events in 180 patients for >85% power (two-sided α = 0.20) to detect an HR = 0.65.

RESULTS

Of 198 patients randomized, median PFS for sorafenib plus mFOLFOX6 was 9.1 months versus 8.7 months for placebo plus mFOLFOX6 (HR = 0.88; 95% CI, 0.64-1.23; P = 0.46). There was no difference between treatment arms for overall survival. Subgroup analyses of PFS and overall survival showed no difference between treatment arms by KRAS or BRAF status (mutant and wild type). The most common grade 3/4 adverse events in the sorafenib and placebo arms were neutropenia (48% vs. 22%), peripheral neuropathy (16% vs. 21%), and grade 3 hand-foot skin reaction (20% vs. 0%). Treatment discontinuation because of adverse events was 9% and 6%, respectively. Generally, dose intensity (duration and cumulative doses) was lower in the sorafenib arm than in the placebo arm.

CONCLUSION

This study did not detect a PFS benefit with the addition of sorafenib to first-line mFOLFOX6 for mCRC. KRAS and BRAF status did not seem to impact treatment outcomes but the subgroups were small. These results do not support further development of sorafenib in combination with mFOLFOX6 in molecularly unselected patients with mCRC.

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.

Colorectal cancer biomarkers and the potential role of cancer stem cells

Over 50% of patients with colorectal cancer (CRC) will progress and/or develop metastases. Biomarkers capable of predicting progression, risk stratification and therapeutic benefit are needed. Cancer stem cells are thought to be responsible for tumor initiation, dissemination and treatment failure. Therefore, we hypothesized that CRC stem cell markers (CRCSC) can identify a group of patients whom are at increased risk for recurrence or progression of disease. If proven correct, these CRCSC biomarkers may herald a paradigm shift in the treatment of this deadly disease. This manuscript reviews current CRC evidence based screening modalities, patient stratification, and summarizes the current state of biomarkers and discusses the novel concept of putative CRCSC's as prognostic biomarkers.

Metronomic chemotherapy for cancer treatment: a decade of clinical studies

PURPOSE

Over the past few years, more and more new selective molecules directed against specific cellular targets have become available for cancer therapy, leading to impressive improvements. In this evolving scenario, a new way of delivering older cytotoxic drugs has also been developing. Many studies demonstrated that several cytotoxic drugs have antiangiogenic properties if administered frequently and at lower doses compared with standard schedules containing maximal tolerated doses (MTD). Such a new strategy, named metronomic chemotherapy, focuses on a different target: the slowly proliferating tumour endothelial cells. About 10 years ago, metronomic chemotherapy was firstly enunciated and hereafter many clinical experiences were published related to almost any cancer disease. This review analyses available studies dealing with metronomic chemotherapy and its combination with several targeted agents in solid tumours.

METHODS

A computerized literature search of MEDLINE was performed using the following search terms: metronomic OR "continuous low dose" AND chemotherapy AND cancer OR solid tumours.

RESULTS

Satisfactory results have been achieved in diverse tumour types, such as breast and prostate cancer or paediatric sarcomas. Moreover, many studies have reported that metronomic chemotherapy determined minimal toxicity compared to MTD chemotherapy. Overall, published series on metronomic schedules are very heterogeneous often reporting on retrospective data, while only very few studies were randomized trials. These limitations still prevent to draw definitive conclusions in diverse tumour types.

CONCLUSIONS

Large well-designed studies are eagerly awaited for confirming the promises of metronomic schedules and their combinations with targeted molecules.

Biomarker analysis in oesophagogastric cancer: Results from the REAL3 and TransMAGIC trials

BACKGROUND

REAL3 (Randomised ECF for Advanced or Locally advanced oesophagogastric cancer 3) was a phase II/III trial designed to evaluate the addition of panitumumab (P) to epirubicin, oxaliplatin and capecitabine (EOC) in untreated advanced oesophagogastric adenocarcinoma, or undifferentiated carcinoma. MAGIC (MRC Adjuvant Gastric Infusional Chemotherapy) was a phase III study which demonstrated that peri-operative epirubicin, cisplatin and infused 5-fluorouracil (ECF) improved survival in early oesophagogastric adenocarcinoma.

PATIENTS AND METHODS

Analysis of response rate (RR; the primary end-point of phase II) and biomarkers in the first 200 patients randomised to EOC or modified dose (m) EOC+P in REAL3 was pre-planned to determine if molecular selection for the on-going study was indicated. KRAS, BRAF and PIK3CA mutations and PTEN expression were assessed in pre-treatment biopsies and results correlated with response to mEOC+P. Association between these biomarkers and overall survival (OS) was assessed in MAGIC patients to determine any prognostic effect.

RESULTS

RR was 52% to mEOC+P, 48% to EOC. Results from 175 assessable biopsies: mutations in KRAS (5.7%), BRAF (0%), PIK3CA (2.5%) and loss of PTEN expression (15.0%). None of the biomarkers evaluated predicted resistance to mEOC+P. In MAGIC, mutations in KRAS, BRAF and PIK3CA and loss of PTEN (phosphatase and tensin homolog) were found in 6.3%, 1.0%, 5.0% and 10.9%, respectively, and were not associated with survival.

CONCLUSIONS

The RR of 52% in REAL3 with mEOC+P met pre-defined criteria to continue accrual to phase III. The frequency of the mutations was too low to exclude any prognostic or predictive effect.

EGFR Expression and KRAS and BRAF Mutational Status in Intestinal-Type Sinonasal Adenocarcinoma

Accumulation of molecular alterations, including EGFR overexpression and mutations in KRAS and BRAF, contribute to colorectal carcinogenesis. Since intestinal-type adenocarcinoma (ITAC) of the nasal cavity and paranasal sinus has morphologic and phenotypic features that are usually indistinguishable from colorectal cancer (CRC), it is likely that both tumor types share equivalent genetic alterations. Data from a series of 43 patients treated surgically for ITAC in Montpellier, France between November 1998 and December 2012 were collected. Tumors were characterized for mutations in KRAS and BRAF as well as EGFR overexpression. Kaplan-Meier survival curves were constructed using overall survival as the primary end points. Patient survival was analyzed using the hazards ratio. Twenty seven tumors (63%) showed EGFR positivity and 30% exhibited a high expression level (+2/+3). KRAS mutations were detected in 43% of cases. BRAF mutations were identified in 3.6% of specimens. Patients with age superior to 60 years, metastatic status, and KRAS mutations had significant overall survival values (p = 0.026, p = 0.001 and p = 0.03, respectively). Our results indicate that KRAS mutations and EGFR expression are frequent in ITAC and that KRAS mutations predict good patient prognosis in ITAC. Finally, EGFR directed molecular treatments could be investigated in a subset of patients affected by ITAC.

Worse prognosis of KRAS c.35 G > A mutant metastatic colorectal cancer (MCRC) patients treated with intensive triplet chemotherapy plus bevacizumab (FIr-B/FOx)

BACKGROUND

Prognosis of KRAS wild-type and mutant metastatic colorectal cancer (MCRC) patients (pts) treated with bevacizumab (BEV)-containing chemotherapy is not significantly different. Since specific KRAS mutations confer different aggressive behaviors, the prognostic role of prevalent KRAS mutations was retrospectively evaluated in MCRC pts treated with first line FIr-B/FOx, associating BEV to triplet chemotherapy.

METHODS

Tumor samples were screened for KRAS codon 12, 13 and BRAF V600E mutations by SNaPshot and/or direct sequencing. MCRC pts <75-years-old were consecutively treated with FIr-B/FOx: weekly 12 hour-timed-flat-infusion/5-fluorouracil (900 mg/m(2) on days 1,2, 8, 9, 15, 16,22, 23), irinotecan plus BEV (160 mg/m(2) and 5 mg/kg, respectively, on days 1,15); and oxaliplatin (80 mg/m(2), on days 8,22). Pts were classified as liver-limited (L-L) and other/multiple metastatic (O/MM). Progression-free survival (PFS) and overall survival (OS) were compared using the log-rank test.

RESULTS

Fifty-nine pts were evaluated at a median follow-up of 21.5 months. KRAS mutant pts: c.35 G > A, 15 (25.4%); c.35 G > T, 7 (11.8%); c.38 G > A, 3 (5%); other, 3 (5%). KRAS wild-type, 31 pts (52.7%). The objective response rate (ORR), PFS and OS were, respectively: c.35 G > A mutant, 71%, 9 months, 14 months; other than c.35 G > A mutants, 61%, 12 months, 39 months. OS was significantly worse in c.35 G > A pts compared to KRAS wild-type (P = 0.002), KRAS/BRAF wild-type (P = 0.03), other MCRC patients (P = 0.002), other than c.35 G > A (P = 0.05), other codon 12 (P = 0.03) mutant pts. OS was not significantly different compared to c.35 G > T KRAS mutant (P = 0.142).

CONCLUSIONS

KRAS c.35 G > A mutant status may be significantly associated with a worse prognosis of MCRC pts treated with first line FIr-B/FOx intensive regimen compared to KRAS/BRAF wild type and other than c.35 G > A mutant pts.

Personalized cancer medicine: molecular diagnostics, predictive biomarkers, and drug resistance

The progressive elucidation of the molecular pathogenesis of cancer has fueled the rational development of targeted drugs for patient populations stratified by genetic characteristics. Here we discuss general challenges relating to molecular diagnostics and describe predictive biomarkers for personalized cancer medicine. We also highlight resistance mechanisms for epidermal growth factor receptor (EGFR) kinase inhibitors in lung cancer. We envisage a future requiring the use of longitudinal genome sequencing and other omics technologies alongside combinatorial treatment to overcome cellular and molecular heterogeneity and prevent resistance caused by clonal evolution.

Molecular dissection of microsatellite instable colorectal cancer

Colorectal cancer was one of the first solid tumors to be classified on the basis of molecular profiling. Microsatellite instability has allowed researchers to distinguish a specific subtype of colorectal cancer that has a clearly identified molecular origin (mismatch repair deficiency), arises on a hereditary and sporadic basis, is linked to a clear clinicopathologic profile, and has prognostic implications. Inconclusive predictive data along with a paucity of targeted drug development have prevented this molecular classification system from being implemented in the clinical setting. New high-throughput genomic data have validated it, thus stressing the fact that it is ready to be applied clinically.

SIGNIFICANCE

Application of a molecular classification of colorectal cancer in the clinical arena is an unmet promise. Recent results of large-scale genomic analyses have provided confirmation and further insights into the molecular biology of already known colorectal cancer subgroups. The quintessential example is the microsatellite instability subgroup, which has been well characterized during the past 2 decades. Future drug development and clinical research initiatives in colorectal oncology should consider these and other known cancer subgroups and start targeting these selected patient populations.

A novel predictive strategy by immunohistochemical analysis of four EGFR ligands in metastatic colorectal cancer treated with anti-EGFR antibodies

PURPOSE

Although KRAS mutation has been identified as a negative predictive biomarker of anti-EGFR antibodies in metastatic colorectal cancer (mCRC), the efficacy in mCRC patients with KRAS wild-type status remains limited. Anti-EGFR antibodies work by blocking ligand binding, but the significance of EGFR ligands in mCRC has not been completely described. This study was conducted to identify the correlation between all seven EGFR ligands and clinical outcomes in mCRC treated with anti-EGFR antibodies. Furthermore, we determined an appropriate predictive strategy for anti-EGFR antibodies using these EGFR ligands.

METHODS

Among 36 mCRC patients who had been treated with cetuximab or panitumumab, we identified 26 mCRC patients with wild-type KRAS status treated properly as the second and further lines and analyzed the relationship between immunoreactivity to seven EGFR ligands and clinical outcomes.

RESULTS

Good clinical outcomes were associated with immunoreactivity against amphiregulin (AR), heparin-binding epidermal growth factor (HB-EGF), transforming growth factor-α (TGF-α), and epiregulin (EREG). Further, patients with immunoreactivity to greater than two of these four ligands (AR, HB-EGF, TGF-α, and EREG) had significantly higher response rate (53.3 vs. 0.0 %, p = 0.004) and disease control rate (93.3 vs. 9.0 %, p = 0.00002) and longer progression-free survival (median PFS: 231 vs. 79 days, p = 0.000008), when compared with patients with immunoreactivity against zero or one ligand.

CONCLUSIONS

Immunohistochemical analysis of four EGFR ligands (AR, HB-EGF, TGF-α, and EREG) might be a novel predictive biomarker and may help optimize patient selection for cetuximab and panitumumab therapy in patients with mCRC.

Monoclonal antibodies in gastrointestinal cancers

INTRODUCTION

Among gastrointestinal cancers, colorectal and gastric neoplasms are the most frequent. The development of new targeted drugs improved the efficacy of systemic therapy in advanced stages of those malignancies.

AREAS COVERED

This review highlights the main biological processes implicated in gastrointestinal cancer development and progression, such as angiogenesis and epidermal growth factor receptor (EGFR) signaling pathway. On these bases, anti-EGFR and anti-vascular endothelial growth factor (VEGF) monoclonal antibodies in colorectal and gastric cancer are discussed. Data about further monoclonal antibodies in development are also reported.

EXPERT OPINION

The use of monoclonal antibodies in colorectal and gastric cancers showed the best outcomes when combined with chemotherapy, even though single agent anti-EGFR antibodies seem active in particular setting of metastatic colorectal cancer (CRC) patients. It is not well defined whether the addition of anti-VEGF and anti-EGFR to chemotherapy could improve outcome in those patients susceptible to CRC-related metastases resection. Little and conflicting data are available about the role of these drugs in adjuvant setting. Tests are available to select patients with higher probability to get benefit from these treatments. Further biomarkers need to be evaluated to improve this selection and achieve "tailorization" of systemic therapy.

Bevacizumab plus chemotherapy in metastatic colorectal cancer patients treated in clinical practice

AIM

The effect of KRAS status on response to bevacizumab plus chemotherapy in metastatic colorectal cancer is still unclear. We aimed to evaluate the overall clinical response to such a therapy in clinical practice and assess the role of KRAS status on therapy response.

PATIENTS & METHODS

This was a retrospective study enrolling 108 metastatic colorectal cancer patients. KRAS mutation analysis was performed by PCR.

RESULTS

Overall, 41.7% of patients had stable disease, 39.8% a partial response, 3.7% a complete response and 14.8% disease progression. Both clinical benefit and objective response rate tended to be higher in patients with only hepatic metastases than those with extrahepatic or multiple metastases. Response to therapy would appear to be independent of KRAS status, but larger studies are needed.

CONCLUSION

Bevacizumab plus chemotherapy provides clinical benefit and objective response rate in patients with metastatic colorectal cancer independently of KRAS expression, especially in those patients with only liver metastases.

Recommendations from the EGAPP Working Group: can testing of tumor tissue for mutations in EGFR pathway downstream effector genes in patients with metastatic colorectal cancer improve health outcomes by guiding decisions regarding anti-EGFR therapy?

SUMMARY OF RECOMMENDATIONS

The Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group (EWG) found that, for patients with metastatic colorectal cancer (mCRC) who are being considered for treatment with cetuximab or panitumumab, there is convincing evidence to recommend clinical use of KRAS mutation analysis to determine which patients are KRAS mutation positive and therefore unlikely to benefit from these agents before initiation of therapy. The level of certainty of the evidence was deemed high, and the magnitude of net health benefit from avoiding potentially ineffective and harmful treatment, along with promoting more immediate access to what could be the next most effective treatment, is at least moderate.The EWG found insufficient evidence to recommend for or against BRAF V600E testing for the same clinical scenario. The level of certainty for BRAF V600E testing to guide antiepidermal growth factor receptor (EGFR) therapy was deemed low. The EWG encourages further studies of the potential value of testing in patients with mCRC who were found to have tumors that are wild type (mutation negative) for KRAS to predict responsiveness to therapy.The EWG found insufficient evidence to recommend for or against testing for mutations in NRAS, or PIK3CA, and/or loss of expression of PTEN or AKT proteins. The level of certainty for this evidence was low. In the absence of supporting evidence, and with consideration of other contextual issues, the EWG discourages the use of these tests in guiding decisions on initiating anti-EGFR therapy with cetuximab or panitumumab unless further evidence supports improved clinical outcomes.

RATIONALE

It has been suggested that patients with mCRC whose tumors harbor certain mutations affecting EGFR pathway signaling are typically unresponsive to therapy with anti-EGFR antibodies (cetuximab and panitumumab). The EWG identified recent evidence reviews that have addressed this topic, and this recommendation statement is based on results of these reviews. In developing these recommendations the EWG considered evidence in the areas described below.

ANALYTIC VALIDITY

Although no research syntheses that have formally evaluated analytic validity of these tests were found, the EWG was able to draw the following conclusions from assessments included in the evidence reviews under consideration. There is adequate evidence that KRAS mutation analysis reliably and accurately detects common mutations (codons 12 and 13), whereas evidence was inadequate for less frequent KRAS mutations (e.g., codon 61). There is also adequate evidence that testing for BRAF V600E accurately and reliably detects the mutation. For common mutations in NRAS, PIK3CA, and expression of PTEN AKT, there is adequate evidence of accurate and reliable detection. However, much less data exist in support. Furthermore, in the specific context of mCRC, no evidence was found on the analytic validity of immunohistochemistry (IHC) assays for PTEN or AKT expression.

CLINICAL VALIDITY

For KRAS mutation analysis, the EWG found convincing evidence for association with treatment response to anti-EGFR therapy, independent of prognostic association. For BRAF V600E mutation testing, the EWG found insufficient evidence for association with treatment response to anti-EGFR therapy independent of prognostic association. The EWG found insufficient evidence for association of results of testing for mutations in NRAS or PIK3CA, and loss of expression of PTEN or ATK proteins, with treatment response to anti-EGFR therapy.

CLINICAL UTILITY

For KRAS mutation analysis, the EWG found adequate evidence that improved health outcomes are achieved by avoiding ineffective chemotherapy and potential side effects and expediting access to the next most effective treatment. Inadequate evidence was found regarding association of BRAF V600E mutation testing or loss of PTEN expression with improved health outcomes among patients with mCRC undergoing anti-EGFR therapy as compared with patients with tumors bearing wild-type BRAF sequence and PTEN expression levels, respectively. No evidence was found to support improved health outcomes associated with testing results for NRAS or PIK3CA variants, or AKT protein expression levels in this clinical scenario.

CONTEXTUAL ISSUES

CRC is an important and highly prevalent health problem. Improvements in mCRC outcomes associated with pharmacogenetic testing could have important clinical, and potentially public health, impacts. Adverse events related to cancer chemotherapy can be common and severe. Therefore, successfully optimizing treatment to maximize efficacy and minimize side effects is important for reducing mCRC-related morbidity and mortality.

Second-line cetuximab/irinotecan versus oxaliplatin/fluoropyrimidines for metastatic colorectal cancer with wild-type KRAS

The goal of the present study was to compare the efficacy of the combination of cetuximab and irinotecan to the combination of oxaliplatin and fluoropyrimidines as second-line chemotherapy in patients with irinotecan-refractory and oxaliplatin-naïve metastatic colorectal cancer (mCRC) harboring wild-type KRAS. The study included 120 patients with mCRC who had progressed after irinotecan-containing first-line chemotherapy and were never treated with oxaliplatin; 40 patients with wild-type KRAS were accrued prospectively in the experimental arm (arm A), and 80 patients accrued retrospectively were divided into control arms B (n = 46) and C (n = 34) according to KRAS genotype. Second-line treatments consisted of cetuximab plus irinotecan for arm A, and oxaliplatin plus either 5-fluorouracil (FOLFOX) or capecitabine (CapeOX) for the control arms. The median progression-free survival (PFS) was 8.3, 5.8 and 3.9 months, for arms A, B and C, respectively, with statistical significance favoring arm A (P = 0.007). Differences in overall survival did not reach statistical significance (18.3 vs 12.6 vs 12.9, P = 0.138), although there was a trend toward longer overall survival in arm A. In terms of benefit from oxaliplatin-containing regimens either as second-line or third-line therapy, the median PFS was 5.0 months in arms B and C as second-line therapy, and 4.0 months in arm A as third-line therapy, with no statistical significance (P = 0.385). Second-line cetuximab plus irinotecan is a valid treatment strategy for mCRC patients with irinotecan-refractory and oxaliplatin-naïve tumors harboring wild-type KRAS. Oxaliplatin-containing chemotherapy resulted in equivalent PFS both as a second-line and a third-line therapy, enabling delay of the administration of FOLFOX and CapeOX until subsequent treatment cycles.

Everolimus in colorectal cancer

INTRODUCTION

There has been a strong preclinical rationale for studying mammalian target of rapamycin (mTOR) inhibitors as single agents or in combination, in multiple malignancies and colorectal cancer in particular.

AREAS COVERED

The authors summarize the complete clinical experience to date of all trials, both published and in abstract form, of everolimus in colorectal cancer. While initial Phase I trials showed promise, further studies have confirmed that single agent everolimus is not active in advanced metastatic colorectal carcinoma with trials showing single agent tolerability, but without significant hints of efficacy in terms of either objective tumor responses or prolonged stable disease. Combination regimens, including combinations with cytotoxic chemotherapy, and inhibitors of VEGF, EGFR and HDAC have been tested specifically in the colorectal setting in Phase I and Phase II clinical trials. The authors discuss the potential reasons for mixed results and suggest future directions for the development of everolimus in colorectal malignancies.

EXPERT OPINION

Studies demonstrate limited clinical activity of everolimus for the treatment of advanced colorectal cancer and have been complicated by increases in toxicity. However, the central role of the PI3K/mTOR pathway in cancer biology suggests that other drug combinations with mTOR inhibition may still merit evaluation.

Comparison of COBAS 4800 KRAS, TaqMan PCR and high resolution melting PCR assays for the detection of KRAS somatic mutations in formalin-fixed paraffin embedded colorectal carcinomas

Many studies documented the influence of KRAS mutation status on the response of patients with metastatic colorectal cancer (mCRC) to anti-EGFR monoclonal antibodies. The COBAS 4800 KRAS is an assay using real time PCR and TaqMelt technology, CE-IVD validated, for the detection of 19 KRAS somatic mutations in exons 2 and 3. We compared COBAS with previously validated PCR TaqMan and High Resolution Melting (HRM) assays on 156 formalin-fixed paraffin embedded (FFPE) specimens of colorectal carcinoma. DNA extraction procedures, using the Qiagen QiAMP kit and the Roche COBAS DNA kit, were also compared. Of the 156 samples, 132 were interpretable using COBAS and TaqMan and 92 using COBAS and HRM. No statistically significant difference was found between COBAS/TaqMan and COBAS/HRM (k = 0.937; p < 0.001 - four discordant cases were found, mostly concerning codon 61 mutations and k = 0.891; p < 0.001 - five discordant cases were found, three regarding codon 61 and two on codon 12/13, respectively). No difference was found between the two DNA extraction methods (t = 1.7185; dol = 39; α = 5 %). The three assays were found suitable to detect accurately KRAS mutations in colon FFPE specimens. COBAS and TaqMan were found to be more robust than HRM, as they yielded fewer non-interpretable results. DNA extraction kits were found to provide equivalent results. The present study shows that pre-screening using COBAS with further TaqMan mutation characterization constitutes an easy and reliable approach for routine diagnostic purposes.

KRAS and BRAF mutation status in circulating colorectal tumor cells and their correlation with primary and metastatic tumor tissue

Although anti-EGFR therapy has established efficacy in metastatic colorectal cancer, only 10-20% of unselected patients respond. This is partly due to KRAS and BRAF mutations, which are currently assessed in the primary tumor. To improve patient selection, assessing mutation status in circulating tumor cells (CTCs), which possibly better represent metastases than the primary tumor, could be advantageous. We investigated the feasibility of KRAS and BRAF mutation detection in colorectal CTCs by comparing three sensitive methods and compared mutation status in matching primary tumor, liver metastasis and CTCs. CTCs were isolated from blood drawn from 49 patients before liver resection using CellSearch™. DNA and RNA was isolated from primary tumors, metastases and CTCs. Mutations were assessed by co-amplification at lower denaturation temperature-PCR (Transgenomic™), real-time PCR (EntroGen™) and nested Allele-Specific Blocker (ASB-)PCR and confirmed by Sanger sequencing. In 43 of the 49 patients, tissue RNA and DNA was of sufficient quantity and quality. In these 43 patients, discordance between primary and metastatic tumor was 23% for KRAS and 7% for BRAF mutations. RNA and DNA from CTCs was available from 42 of the 43 patients, in which ASB-PCR was able to detect the most mutations. Inconclusive results in patients with low CTC counts limited the interpretation of discrepancies between tissue and CTCs. Determination of KRAS and BRAF mutations in CTCs is challenging but feasible. Of the tested methods, nested ASB-PCR, enabling detection of KRAS and BRAF mutations in patients with as little as two CTCs, seems to be superior.

Low percentage of KRAS mutations revealed by locked nucleic acid polymerase chain reaction: implications for treatment of metastatic colorectal cancer

Metastatic colorectal cancer (mCRC) is frequently characterized by the presence of mutations of the KRAS oncogene, which are generally associated with a poor response to treatment with anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibodies. With the methods currently used, a case is classified as KRAS-mutated when approximately 20% of the cells bear an activating KRAS mutation. These considerations raise the question of whether cells with a mutated KRAS can be found in mCRC cases classified as KRAS wild-type when more sensitive methods are used. In addition, the issue arises of whether these mCRC cases with low proportion of KRAS-mutated cells could account at least in part for the therapeutic failure of anti-EGFR therapies that occur in 40-60% of cases classified as KRAS wild type. In this study, we compared the classical assays with a very sensitive test, a locked nucleic acid (LNA) polymerase chain reaction (PCR), capable of detecting KRAS-mutated alleles at extremely low frequency (detection sensitivity limit 0.25% mutated DNA/wild-type DNA). By analyzing a cohort of 213 mCRC patients for KRAS mutations, we found a 20.6% discordance between the sequencing/TheraScreen methods and the LNA-PCR. Indeed, 44 mCRC patients initially considered KRAS wild type were reclassified as KRAS mutated by using the LNA-PCR test. These patients were more numerous among individuals displaying a clinical failure to anti-EGFR therapies. Failure to respond to these biological treatments occurred even in the absence of mutations in other EGFR pathway components such as BRAF.

A prospective multicenter phase II study evaluating multimodality treatment of patients with peritoneal carcinomatosis arising from appendiceal and colorectal cancer: the COMBATAC trial

Background

Peritoneal carcinomatosis is regarded as a common sign of advanced tumor stage, tumor progression or local recurrence of appendiceal and colorectal cancer and is generally associated with poor prognosis. Although survival of patients with advanced stage CRC has markedly improved over the last 20 years with systemic treatment, comprising combination chemotherapy +/− monoclonal antibodies, the oncological outcome—especially of the subgroup of patients with peritoneal metastases—is still unsatisfactory. In addition to systemic therapy, cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are specific treatment options for a selected group of these patients and may provide an additional therapeutic benefit in the framework of an interdisciplinary treatment concept.

Methods/design

The COMBATAC trial is a prospective, multicenter, open-label, single-arm, single-stage phase II trial investigating perioperative systemic polychemotherapy including cetuximab in combination with CRS and HIPEC patients with histologically proven wild-type KRAS colorectal or appendiceal adenocarcinoma and synchronous or metachronous peritoneal carcinomatosis. The planned total number of patients to be recruited is 60. The primary endpoint is progression-free survival (PFS). Secondary endpoints include overall survival (OS), perioperative morbidity and treatment-associated toxicity, feasibility of the combined treatment regimen, quality of life (QoL) and histopathological regression after preoperative chemotherapy.

Discussion

The COMBATAC trial is designed to evaluate the feasibility and efficacy of the combined multidisciplinary treatment regimen consisting of perioperative systemic combination chemotherapy plus cetuximab and CRS plus bidirectional HIPEC with intraperitoneal oxaliplatin.

Trial registration

ClinicalTrials.gov Identifier: NCT01540344, EudraCT number: 2009-014040-11

Optimization of routine KRAS mutation PCR-based testing procedure for rational individualized first-line-targeted therapy selection in metastatic colorectal cancer

KRAS mutation detection represents a crucial issue in metastatic colorectal cancer (mCRC). The optimization of KRAS mutation detection delay enabling rational prescription of first-line treatment in mCRC including anti-EGFR-targeted therapy requires robust and rapid molecular biology techniques. Routine analysis of mutations in codons 12 and 13 on 674 paraffin-embedded tissue specimens of mCRC has been performed for KRAS mutations detection using three molecular biology techniques, that is, high-resolution melting (HRM), polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP), and allelic discrimination PCR (TaqMan PCR). Discordant cases were assessed with COBAS 4800 KRAS CE-IVD assay. Among the 674 tumor specimens, 1.5% (10/674) had excessive DNA degradation and could not be analyzed. KRAS mutations were detected in 38.0% (256/674) of the analysable specimens (82.4% in codon 12 and 17.6% in codon 13). Among 613 specimens in whom all three techniques were used, 12 (2.0%) cases of discordance between the three techniques were observed. 83.3% (10/12) of the discordances were due to PCR-RFLP as confirmed by COBAS 4800 retrospective analysis. The three techniques were statistically comparable (κ > 0.9; P < 0.001). From these results, optimization of the routine procedure consisted of proceeding to systematic KRAS detection using HRM and TaqMan and PCR-RFLP in case of discordance and allowed significant decrease in delays. The results showed an excellent correlation between the three techniques. Using HRM and TaqMan warrants high-quality and rapid-routine KRAS mutation detection in paraffin-embedded tumor specimens. The new procedure allowed a significant decrease in delays for reporting results, enabling rational prescription of first-line-targeted therapy in mCRC.

Biomarkers of benefit from cetuximab-based therapy in metastatic colorectal cancer: interaction of EGFR ligand expression with RAS/RAF, PIK3CA genotypes

Background

More than half of patients with KRAS-wild type advanced colorectal cancer (CRC) fail anti-EGFR monoclonal antibodies. We studied EGFR-axis messenger RNA (mRNA) expression and RAS, RAF, PIK3CA mutations in order to identify additional biomarkers of cetuximab efficacy.

Methods

Previously genotyped (KRAS, NRAS, BRAF, PIK3CA mutations) formalin-fixed paraffin-embedded tumour biopsies of 226 cetuximab-treated CRC patients (1st to 3rd line therapy) were assessed for mRNA expression of epidermal growth factor receptor (EGFR) and its ligands EGF, Transofrming Growth Factor-a (TGFA), Amphiregulin (AREG) and Epiregulin (EREG) with real time quantitative PCR. Mutations were detected in 72 (31.9%) tumours for KRAS, in 6 (2.65%) for BRAF, in 7 (3.1%) for NRAS and in 37 (16.4%) for PIK3CA.

Results

Only PIK3CA mutations occasionally coexisted with other gene mutations. In univariate analysis, prognostic significance for survival ( from metastases until death) was seen for BRAF mutations (Hazard Ratio HR 8.1, 95% CI 3.4-19), codon 12-only KRAS mutations (HR 1.62, 95% CI 1.1-2.4), high AREG mRNA expression only in KRAS wild type CRC (HR 0.47, 95% CI 0.3-0.7) and high EREG mRNA expression irrespective of KRAS mutation status (HR 0.45, 95% CI 0.28-0.7). EREG tumoural mRNA expression was significantly associated with a 2.26-fold increased likelihood of objective response to cetuximab therapy (RECIST 1.1). In multivariate analysis, favourable predictive factors were high AREG mRNA in KRAS wild type tumours, high EREG mRNA, low Ephrin A2 receptor mRNA. Cetuximab-treated patients with AREG-low KRAS wild type CRC fared very poorly, their survival being similar to KRAS mutant CRC. Patients with KRAS codon 13 or other non-codon 12 mutations had a median survival (30 months, 95% CI 20–35) similar to that of patients with KRAS wild-type (median survival 29 months, 95% CI 25–35), in contrast to patients with KRAS codon 12 mutations who fared worse (median survival 19 months, 95% CI 15–26).

Conclusions

BRAF and codon 12 KRAS mutations predict for adverse outcome of CRC patients receiving cetuximab. AREG mRNA reflects EGFR signalling in KRAS wild type tumours, predicting for cetuximab efficacy when high and failure when low. EREG may have a prognostic role independent of KRAS mutation.

Therapeutic implications of DNA mismatch repair in adjuvant colorectal cancer chemotherapy

SUMMARY Microsatellite instability (MSI) is a molecular marker of defective DNA mismatch repair (MMR) and constitutes an important oncogenic molecular pathway in colorectal cancer that is present in approximately 12–15% of all colorectal malignant tumors. Defective MMR status in colorectal cancer occurs as a result of germline mutations in MMR genes (less than one third of cases) or, more commonly, from somatic hypermethylation of the MLH1 promoter (more than two thirds). MMR deficiency accelerates colorectal oncogenesis by accumulation of secondary mutations in specific target genes. Patients with defective MMR tumors have distinct clinicopathologic characteristics and have been associated with a better stage-adjusted prognosis than patients with proficient MMR tumors. MMR deficiency may predict tumor chemoresistance to adjuvant 5-fluorouracil treatment. Preliminary clinical data suggested that adding oxaliplatin to 5-fluorouracil could restore the benefit of adjuvant chemotherapy in MSI patients. Further studies are needed to clarify the differential chemosensitivity of MSI patients depending on the mechanism of MMR deficiency and the adjuvant chemotherapeutic regimen used.

Defining resectability of colorectal liver metastases: how and why?

SUMMARY Treatment outcome in metastatic colorectal carcinoma has improved because of advancements in medical therapy and increased use of liver resections. In primary nonresectable disease, prognosis improves when a secondary resection is performed after successful downsizing by neoadjuvant systemic therapy. Which patient groups may profit from a secondary liver resection and which neoadjuvant systemic therapy has the optimal chance of conversion to resectability has not been defined because various patient groups were selected in different studies and there is a lack of consensus on resectability. This invalidates cross-study comparisons of resection rates and survival rates. Prospective trials in which secondary resection rate is a predefined end point are needed and will allow more insight into this topic.

Systemic cytotoxic and biological therapies of colorectal liver metastases: expert consensus statement

Systemic therapy for colorectal cancer liver metastases (CRLM) has undergone significant development in the past 15 years. Therapy regimens consisting of combinations of cytotoxic chemotherapeutic agents have demonstrated greater efficacy and contributed to a significant survival improvement. As the majority of patients who undergo resection for liver-only CRLM are at risk of disease recurrence and cancer-related death, combining resection with systemic therapy appears sensible. However, trial-based evidence is sparse to support this concept. Peri-operative FOLFOX has demonstrated a progression-free survival benefit in a single Phase III trial; the safety of chemotherapy and subsequent operations was acceptable and only a few patients showed initial progression. Chemotherapy-associated liver injury (CALI), including sinusoidal obstruction syndrome and steatohepatitis, has been observed after cytotoxic therapy, and should have implications for chemotherapy plans prior to hepatectomy. In general, pre-operative chemotherapy should not extend beyond 3 months. For patients with unresectable liver-only CRLM, a response to chemotherapy could establish resectability and should be considered an initial treatment goal. In patients with unresectable CRLM, oxaliplatin- or irinotecan-containing combinations represent the standard options, although single-agent choices may be appropriate for individual patients. The addition of bevacizumab carries the potential for a greater response and possibly for reduced CALI risks. In tumours without K-ras mutations, anti-epidermal growth factor receptor (EGFR) agents are also reasonable choices for a greater response and improved survival outcomes. It is crucial that all systemic CRLM treatment decisions include proper definitions of treatment goals and endpoints, and are derived based on appropriate multidisciplinary considerations for other potentially applicable local or regional modalities.

Targeted therapy in metastatic colorectal cancer -- an example of personalised medicine in action

In metastatic colorectal cancer (mCRC), an improved understanding of the underlying pathology and molecular biology has successfully merged with advances in diagnostic techniques and local/systemic therapies as well as improvements in the functioning of multidisciplinary teams, to enable tailored treatment regimens and optimized outcomes. Indeed, as a result of these advancements, median survival for patients with mCRC is now in the range of 20-24months, having approximately tripled in the last 20years. The identification of KRAS as a negative predictive marker for activity of epidermal growth factor receptor (EGFR)-targeted monoclonal antibodies (mAbs), such as panitumumab (Amgen, Thousand Oaks, USA) and cetuximab (ImClone, Branchburg, USA), has perhaps had the greatest impact on patient management. This meant that, for the first time, mCRC patients unlikely to respond to a targeted therapy could be defined ahead of treatment. Ongoing controversies such as whether patients with KRAS G13D- (or BRAF V600-) mutated tumours can still respond to EGFR-targeted mAbs and the potential impact of inter- and intra-tumour heterogeneity on tumour sampling show that the usefulness of KRAS as a biomarker has not yet been exhausted, and that other downstream biomarkers should be considered. Conversely, a predictive biomarker for anti-angiogenic agents such as bevacizumab (Genentech, San Francisco, USA) in the mCRC setting is still lacking. In this review we will discuss the discovery and ongoing investigation into predictive biomarkers for mCRC as well as how recent advances have impacted on clinical practice and ultimately the overall cost of treatment for these patients.

Safety and feasibility of targeted agent combinations in solid tumours

The plethora of novel molecular-targeted agents (MTAs) has provided an opportunity to selectively target pathways involved in carcinogenesis and tumour progression. Combination strategies of MTAs are being used to inhibit multiple aberrant pathways in the hope of optimizing antitumour efficacy and to prevent development of resistance. While the selection of specific agents in a given combination has been based on biological considerations (including the role of the putative targets in cancer) and the interactions of the agents used in combination, there has been little exploration of the possible enhanced toxicity of combinations resulting from alterations in multiple signalling pathways in normal cell biology. Owing to the complex networks and crosstalk that govern normal and tumour cell proliferation, inhibiting multiple pathways with MTA combinations can result in unpredictable disturbances in normal physiology. This Review focuses on the main toxicities and the lack of tolerability of some common MTA combinations, particularly where evidence of enhanced toxicity compared to either agent alone is documented or there is development of unexpected toxicity. Toxicities caused by MTA combinations highlight the need to introduce new preclinical testing paradigms early in the drug development process for the assessment of chronic toxicities resulting from such combinations.

Bevacizumab plus chemotherapy as salvage treatment in chemorefractory patients with metastatic colorectal cancer

Purpose

The combination of chemotherapy and bevacizumab, a monoclonal antibody targeting the vascular endothelial growth factor, is consistently being used as first- and second-line treatment in patients with metastatic colorectal cancer (mCRC). There is little data of the activity of bevacizumab in chemorefractory mCRC patients. The aim of this retrospective single center study was to evaluate the activity of bevacizumab combined with chemotherapy in this study population.

Methods

Forty-six consecutive mCRC patients treated in the University Hospital Gasthuisberg (Leuven, Belgium) receiving bevacizumab in advanced lines following failure of conventional chemotherapy were included in this study. Treatment regimen consisted of bevacizumab 5 mg/kg in combination with leucovorin, 5-fluorouracil, and oxaliplatin (FOLFOX) or leucovorin, 5-fluorouracil, and irinotecan (FOLFIRI).

Results

Bevacizumab plus chemotherapy was used in third-line treatment in eight (17%) patients and in fourth-line treatment or more in 38 patients (83%). All patients previously failed irinotecan-based chemotherapy, 44 (96%) failed oxaliplatin-based regimens, and 40 (87%) failed treatment with cetuximab. Bevacizumab was given in combination with irinotecan-based chemotherapy in 36 patients, oxaliplatin-based chemotherapy in nine patients, and with single agent 5-fluorouracil in one patient. Objective response was demonstrated in ten patients (22%) and disease control in 38 (83%) with a median progression-free survival of 8.9 months and a median overall survival of 13.8 months. Only four patients experienced grade III and above bevacizumab-related toxicity.

Conclusion

Taking into account the retrospective nature of the study which can influence the selection of patients, bevacizumab given in advanced lines after failure of conventional chemotherapy and antiepidermal growth factor receptor agents can result in high disease control rates in patients with mCRC.

HER2 gene copy number status may influence clinical efficacy to anti-EGFR monoclonal antibodies in metastatic colorectal cancer patients

BACKGROUND

In metastatic colorectal cancer (mCRC), KRAS is the only validated biomarker used to select patients for administration of epidermal growth factor receptor (EGFR)-targeted therapies. To identify additional predictive markers, we investigated the importance of HER2, the primary EGFR dimerisation partner, in this particular disease.

METHODS

We evaluated the HER2 gene status by fluorescence in situ hybridisation (FISH) in 170 KRAS wild-type mCRC patients treated with cetuximab or panitumumab.

RESULTS

Depending on HER2 gene copy number status, patients showed three distinct cytogenetic profiles: 4% of patients had HER2 gene amplification (R:HER2/CEP17 ≥ 2) in all neoplastic cells (HER2-all-A), 61% of patients had HER2 gain due to polysomy or to gene amplification in minor clones (HER2-FISH+*), and 35% of patients had no or slight HER2 gain (HER2-FISH-). These subgroups were significantly correlated with different clinical behaviours, in terms of response rate (RR; P=0.0006), progression-free survival (PFS; P<0.0001) and overall survival (OS; P<0.0001). Patients with HER2-all-A profile experienced the worst outcome, patients with HER2-FISH- profile showed an intermediate behaviour and patients with HER2-FISH+* profile were related to the highest survival probability (median PFS in months: 2.5 vs 3.9 vs 7.6, respectively; median OS in months: 4.2 vs 9.7 vs 13, respectively).

CONCLUSION

HER2 gene copy number status may influence the clinical response to anti-EGFR-targeted therapy in mCRC patients.

Utility of prognostic genomic tests in breast cancer practice: The IMPAKT 2012 Working Group Consensus Statement

BACKGROUND

We critically evaluated the available evidence on genomic tests in breast cancer to define their prognostic ability and likelihood to determine treatment benefit.

DESIGN

Independent evaluation of six genomic tests [Oncotype Dx™, MammaPrint(®), Genomic Grade Index, PAM50 (ROR-S), Breast Cancer Index, and EndoPredict] was carried out by a panel of experts in three parameters: analytical validity, clinical validity, and clinical utility based on the principles of the EGAPP criteria. PANEL STATEMENTS: The majority of the working group members found the available evidence on the analytical and clinical validity of Oncotype Dx™ and MammaPrint(®) to be convincing. None of the genomic tests demonstrated robust evidence of clinical utility: it was not clear from the current evidence that modifying treatment decisions based on the results of a given genomic test could result in improving clinical outcome.

CONCLUSIONS

The IMPAKT 2012 Working Group proposed the following recommendations: (i) a need to develop models that integrate clinicopathologic factors along with genomic tests; (ii) demonstration of clinical utility should be made in the context of a prospective randomized trial; and (iii) the creation of registries for patients who are subjected to genomic testing in the daily practice.