Jolien Tol

BRAF Mutation in Metastatic Colorectal Cancer

To the Editor: We recently found that progression-free survival was shorter among patients with metastatic colorectal cancer treated with chemotherapy, bevacizumab, and cetuximab (CBC regimen) than among patients who received chemotherapy and bevacizumab alone (CB regimen) (Feb. 5 issue).1 Other investigators have found that the efficacy of cetuximab is limited to patients with wild-type–KRAS tumors.2 In a subgroup of 520 patients with available tumor samples, we observed a shorter median progression-free survival among patients with a mutated-KRAS oncogene in the CBC group than among patients with mutated-KRAS tumors who received the CB regimen and among patients with .xa0.xa0.

KRAS mutation analysis: a comparison between primary tumours and matched liver metastases in 305 colorectal cancer patients

Background:KRAS mutation is a negative predictive factor for treatment with anti-epidermal growth factor receptor antibody in metastatic colorectal cancer (CRC). KRAS mutation analysis is usually performed on primary tumour tissue because metastatic tissue is often not available. However, controversial data are available on the concordance of test results between primary tumours and corresponding metastases. We assessed the concordance of KRAS mutation status in a study of 305 primary colorectal tumours and their corresponding liver metastases.Methods:Patients with histologically confirmed CRC who underwent surgical resection of the primary tumour and biopsy or surgical resection of the corresponding liver metastasis were included. KRAS mutation analysis was performed for codons 12 and 13.Results:KRAS mutation was detected in 108 out of 305 primary tumours (35.4%). In 11 cases (3.6%), we found a discordance between primary tumour and metastasis: 5 primary tumours had a KRAS mutation with a wild-type metastasis, 1 primary tumour was wild type with a KRAS mutation in the metastasis, and in 5 cases the primary tumour and the metastasis had a different KRAS mutation.Conclusion:We observed a high concordance of KRAS mutation status of 96.4% (95% CI 93.6–98.2%) between primary colorectal tumours and their corresponding liver metastases. In only six patients (2.0%; 95% CI 0.7–4.2%), the discordance was clinically relevant. In this largest and most homogenous study to date, we conclude that both primary tumours and liver metastases can be used for KRAS mutation analysis.

Maintenance treatment with capecitabine and bevacizumab in metastatic colorectal cancer (CAIRO3): a phase 3 randomised controlled trial of the Dutch Colorectal Cancer Group

BACKGROUNDnThe optimum duration of first-line treatment with chemotherapy in combination with bevacizumab in patients with metastatic colorectal cancer is unknown. The CAIRO3 study was designed to determine the efficacy of maintenance treatment with capecitabine plus bevacizumab versus observation.nnnMETHODSnIn this open-label, phase 3, randomised controlled trial, we recruited patients in 64 hospitals in the Netherlands. We included patients older than 18 years with previously untreated metastatic colorectal cancer, with stable disease or better after induction treatment with six 3-weekly cycles of capecitabine, oxaliplatin, and bevacizumab (CAPOX-B), WHO performance status of 0 or 1, and adequate bone marrow, liver, and renal function. Patients were randomly assigned (1:1) to either maintenance treatment with capecitabine and bevacizumab (maintenance group) or observation (observation group). Randomisation was done centrally by minimisation, with stratification according to previous adjuvant chemotherapy, response to induction treatment, WHO performance status, serum lactate dehydrogenase concentration, and treatment centre. Both patients and investigators were aware of treatment assignment. We assessed disease status every 9 weeks. On first progression (defined as PFS1), patients in both groups were to receive the induction regimen of CAPOX-B until second progression (PFS2), which was the studys primary endpoint. All endpoints were calculated from the time of randomisation. Analyses were done by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00442637.nnnFINDINGSnBetween May 30, 2007, and Oct 15, 2012, we randomly assigned 558 patients to either the maintenance group (n=279) or the observation group (n=279). Median follow-up was 48 months (IQR 36-57). The primary endpoint of median PFS2 was significantly improved in patients on maintenance treatment, and was 8·5 months in the observation group and 11·7 months in the maintenance group (HR 0·67, 95% CI 0·56-0·81, p<0·0001). This difference remained significant when any treatment after PFS1 was considered. Maintenance treatment was well tolerated, although the incidence of hand-foot syndrome was increased (64 [23%] patients with hand-foot skin reaction during maintenance). The global quality of life did not deteriorate during maintenance treatment and was clinically not different between treatment groups.nnnINTERPRETATIONnMaintenance treatment with capecitabine plus bevacizumab after six cycles of CAPOX-B in patients with metastatic colorectal cancer is effective and does not compromise quality of life.nnnFUNDINGnDutch Colorectal Cancer Group (DCCG). The DCCG received financial support for the study from the Commissie Klinische Studies (CKS) of the Dutch Cancer Foundation (KWF), Roche, and Sanofi-Aventis.

Markers for EGFR pathway activation as predictor of outcome in metastatic colorectal cancer patients treated with or without cetuximab

BACKGROUNDnAnti-EGFR monoclonal antibodies in metastatic colorectal cancer (mCRC) treatment are only effective in patients with KRAS wild type tumours. Here we assess the predictive value of other potential relevant markers involved in the epidermal growth factor receptor (EGFR) signalling pathways for response to cetuximab-based treatment.nnnMATERIALS AND METHODSnFormalin-fixed paraffin-embedded colorectal cancer tissue of the primary tumour was obtained from 559 mCRC patients treated with chemotherapy and bevacizumab with or without cetuximab (phase III CAIRO2 study). DNA was isolated for mutation analysis of BRAF (V600E), KRAS (codon 12 and 13) and PIK3CA (exon 9 and 20). Tissue microarrays (TMAs) were constructed for the assessment of EGFR and HER2 gene copy number (GCN), and EGFR and PTEN protein expression. The results of these markers, individually or in combination, were correlated with progression-free survival (PFS) and overall survival (OS) in the subgroup of patients with a KRAS wild type tumour treated in the cetuximab-arm. KRAS wild type patients treated without cetuximab were used as a control group.nnnRESULTSnA total of 208 tumours (39.4%) contained a KRAS mutation, 8.7% a BRAF mutation and 9.9% a PIK3CA mutation. Loss of PTEN expression and the presence EGFR protein expression were observed in 42.0% and 61.7% of the samples, respectively. An increased EGFR GCN was observed in 15.3% of the samples, and 11.5% of the evaluable samples contained an increased HER2 GCN. In KRAS wild type patients treated with cetuximab a BRAF mutation was significantly and independently associated with PFS and OS. In patients treated without cetuximab the PFS and OS were also associated with the BRAF genotype. No prognostic or predictive value was observed for any of the other markers when tested individually or in combination.nnnCONCLUSIONSnBRAF genotype is correlated with PFS and OS in KRAS wild type mCRC patients, which is independent of cetuximab treatment. PIK3CA mutation, loss of PTEN expression, EGFR GCN and HER2 GCN have no predictive value for response to treatment with cetuximab, neither individually nor in combination with other markers.

A randomised phase III study on capecitabine, oxaliplatin and bevacizumab with or without cetuximab in first-line advanced colorectal cancer, the CAIRO2 study of the Dutch Colorectal Cancer Group (DCCG). An interim analysis of toxicity

BACKGROUNDnTargeting the vascular endothelial growth factor or the epidermal growth factor receptor (EGFR) has shown efficacy in advanced colorectal cancer (ACC), but no data are available on the combination of these strategies with chemotherapy in the first-line treatment. The CAIRO2 study evaluates the effect of adding cetuximab, a chimeric mAb against EGFR, to capecitabine, oxaliplatin and bevacizumab in the first-line treatment of ACC.nnnPATIENTS AND METHODSnIn all, 755 patients were randomly assigned between treatment with capecitabine, oxaliplatin and bevacizumab with or without cetuximab. The primary end point is progression-free survival. We here present the toxicity results in the first 400 patients that entered the study.nnnRESULTSnThe incidence of overall grade 3-4 toxicity was significantly higher in arm B compared with arm A (81% versus 72%, P = 0.03). This difference is fully attributed to cetuximab-related skin toxicity. The addition of cetuximab did not result in an increase of gastrointestinal toxicity or treatment-related mortality.nnnCONCLUSIONSnThe addition of cetuximab to capecitabine, oxaliplatin and bevacizumab in the first-line treatment of ACC appears to be safe and feasible. No excessive or unexpected toxicity in the cetuximab-containing treatment arm was observed.

Circulating tumour cells early predict progression-free and overall survival in advanced colorectal cancer patients treated with chemotherapy and targeted agents

BACKGROUNDnEarly predictive markers for response are needed for advanced colorectal cancer (ACC) patients. We assessed the value of circulating tumour cells (CTC) in ACC patients treated with chemotherapy plus targeted agents (CAIRO2 phase III trial) and compared the results with computed tomography (CT) imaging.nnnMATERIALS AND METHODSnCTC were determined at baseline and at different time points during treatment. Patients were stratified into low (less than three CTC per 7.5 ml of blood) or high CTC (three or more CTC per 7.5 ml of blood).nnnRESULTSnA total of 467 patients were assessable for CTC analysis. Among them, 129 patients (29%) with high baseline CTC had a significantly decreased progression-free survival [PFS; hazard ratio (HR) 1.5] and overall survival (OS; HR 2.2) compared with 322 patients with low baseline CTC. This difference remained statistically significant during treatment. The sensitivity and specificity of high CTC at baseline for the prediction of progressive disease on CT imaging were 16.7% and 70.1%, respectively, and of high CTC at 1-2 weeks after the start of treatment 20.0% and 95.1%, respectively. The combined analysis of CTC and CT imaging provided a more accurate outcome assessment than either modality alone.nnnCONCLUSIONSnThe CTC count before and during treatment independently predicts PFS and OS in ACC patients treated with chemotherapy plus targeted agents and provides additional information to CT imaging.

Monoclonal antibodies in the treatment of metastatic colorectal cancer: A review

BACKGROUNDnTwo groups of agents targeting either the vascular endothelial growth factor (VEGF) receptor or the epidermal growth factor receptor (EGFR) have been added to the therapeutic arsenal against metastatic colorectal cancer (mCRC). Currently available agents in these groups are the anti-VEGF antibody bevacizumab and the anti-EGFR antibodies cetuximab and panitumumab.nnnOBJECTIVESnThis article reviews the results of prospective randomized clinical trials of anti-VEGF and anti-EGFR antibodies in mCRC, either as monotherapy, combined with chemotherapy, or combined with each other. Also reviewed are retrospective subset analyses of the effect of a KRAS mutation on the response to anti-EGFR antibodies.nnnMETHODSnMEDLINE (2004-2009) was searched for randomized Phase II-III clinical trials of monoclonal antibodies in mCRC published in English. The search terms were colorectal neoplasms, bevacizumab, cetuximab, panitumumab, and KRAS mutation, alone or in combination. Information on the effect of KRAS mutation status on the response to anti-EGFR antibodies was drawn from retrospective subset analyses within the selected trials.nnnRESULTSnThe literature search identified 5 trials of bevacizumab in mCRC. Of these trials, 3 found a significant benefit on the primary end point (progression-free survival [PFS] or overall survival [OS]) when bevacizumab was added to chemotherapy, either as first-line (2 trials) or second-line (1 trial) treatment. The literature search identified 5 trials of cetuximab and 1 trial of panitumumab in mCRC. Of these trials, 4 found a significant benefit on the primary end point (response rate, PFS, or OS) with cetuximab or panitumumab as monotherapy or added to chemotherapy, either as first-line (1 trial) or later-line (3 trials) treatment. In all trials, the benefit of anti-EGFR therapy was limited to patients who had KRAS wild-type tumors. Of 3 identified trials of combined anti-EGFR and anti-VEGF therapy, 2 found that the combination of an anti-EGFR antibody and the anti-VEGF antibody bevacizumab had a significant negative effect on the primary end point (PFS) compared with no added anti-EGFR antibody.nnnCONCLUSIONSnIn the studies reviewed, the anti-VEGF antibody bevacizumab added to chemotherapy and the anti-EGFR antibodies cetuximab and panitumumab as monotherapy or added to chemotherapy were associated with consistent efficacy in the treatment of mCRC, although the absolute benefit differed among trials. The efficacy of anti-EGFR antibodies was limited to patients with KRAS wild-type tumors. Given the lack of benefit when anti-VEGF and anti-EGFR antibodies were combined, such regimens should not be used in clinical practice.

Relationship between Single Nucleotide Polymorphisms and Haplotypes in DPYD and Toxicity and Efficacy of Capecitabine in Advanced Colorectal Cancer

Purpose: To explore the effect of dihydropyrimidine dehydrogenase (DPD) single nucleotide polymorphisms (SNP) and haplotypes on outcome of capecitabine. Experimental Design: Germline DNA was available from 568 previously untreated patients with advanced colorectal cancer participating in the CAIRO2 trial, assigned to capecitabine, oxaliplatin, and bevacizumab ± cetuximab. The coding region of dihydropyrimidine dehydrogenase gene (DPYD) was sequenced in 45 cases with grade 3 or more capecitabine-related toxicity and in 100 randomly selected controls (cohort). Most discriminating (P < 0.1) or frequently occurring (>1%) nonsynonymous SNPs were analyzed in all 568 patients. SNPs and haplotypes were associated with toxicity, capecitabine dose modifications, and survival. Results: A total of 29 SNPs were detected in the case–cohort analysis, of which 8 were analyzed in all 568 patients. Of the patients polymorphic for DPYD IVS14+1G>A, 2846A>T, and 1236G>A, 71% (5 of 7), 63% (5 of 8), and 50% (14 of 28) developed grade 3 to 4 diarrhea, respectively, compared with 24% in the overall population. All patients polymorphic for IVS14+1G>A developed any grade 3 to 4 toxicity, including one possibly capecitabine-related death. Because of toxicity, a mean capecitabine dose reduction of 50% was applied in IVS14+1G>A and 25% in 2846A>T variant allele carriers. Patients were categorized into six haplotype groups: one predicted for reduced (10%), and two for increased risks (41% and 33%) for severe diarrhea. Individual SNPs were not associated with overall survival, whereas one haplotype was associated with overall survival [HR (95% CI) = 0.57 (0.35–0.95)]. Conclusions: DPYD IVS14+1G>A and 2846A>T predict for severe toxicity to capecitabine, for which patients require dose reductions. Haplotypes assist in selecting patients at risk for toxicity to capecitabine. Clin Cancer Res; 17(10); 3455–68. ©2011 AACR.

High sensitivity of both sequencing and real-time PCR analysis of KRAS mutations in colorectal cancer tissue.

The KRAS mutation status predicts the outcome of treatment with epidermal growth factor receptor targeted agents, and therefore the testing for KRAS mutations has become an important diagnostic procedure. To optimize the quality of this test, we compared the results of the two most commonly used KRAS mutation tests, cycle sequencing and a real‐time PCR‐based assay, in DNA extracted from formalin‐fixed paraffin‐embedded (FFPE) colorectal cancer samples of 511 patients. The results were interpreted in the context of the tumour cell percentage and the assay parameters. In 510 samples KRAS mutation status assessment was successful. A KRAS mutation was detected in 201 tumours (39.4%). Sequencing and the real‐time PCR‐based assay generated the same result in 486 samples (95.3%). The sequencing result was considered false positive in one (0.2%) and false negative in nine samples (1.8%). The assay result was considered false positive in six (1.2%) and false negative in seven samples (1.4%). Explanations for discrepant test results were a higher sensitivity of the assay in samples with a low tumour cell percentage, occurrence of mutations that are not covered by the assay and δ Ct values approximating the cut‐off value of the assay. In conclusion, both sequencing and the real‐time PCR‐based assay are reliable tests for KRAS mutation analysis in FFPE colorectal cancer samples, with a sensitivity of 95.5% (95% confidence interval [CI] 91.7–97.9%) and 96.5% (95% CI 93.0–98.6%), respectively. The real‐time PCR based assay is the method of choice in samples with a tumour cell percentage below 30%.

Correlation of FCGR3A and EGFR germline polymorphisms with the efficacy of cetuximab in KRAS wild-type metastatic colorectal cancer.

BACKGROUNDnNext to KRAS mutation status, additional predictive markers are needed for the response to cetuximab in patients with metastatic colorectal cancer (mCRC). Previous studies indicated that germline polymorphisms in specific genes may predict efficacy and toxicity of cetuximab in mCRC patients.nnnMETHODSnGermline DNA was isolated from 246 KRAS wild-type mCRC patients who were treated in the phase III CAIRO2 study with chemotherapy and bevacizumab alone or with the addition of cetuximab. Associations of epidermal growth factor (EGF) 61A>G, EGF receptor (EGFR) CA(14-22), cyclin D1 (CCND1) 932G>A, fragment-C gamma receptor (FCGR) 2A 535A>G and FCGR3A 818A>C polymorphisms with progression-free survival (PFS) and cetuximab-related skin toxicity were studied.nnnRESULTSnIn cetuximab-treated patients, the FCGR3A 818C-allele was associated with decreased PFS compared with the FCGR3A 818AA genotype (median PFS, 8.2 [95%CI, 6.7-10.3] versus 12.8 [95%CI, 10.3-14.7] months, respectively; HR, 1.57 [95%CI, 1.06-2.34]; P=.025). The EGFR20 genotype was associated with decreased PFS compared with the EGFR<20 genotype (median PFS, 7.6 [95%CI, 6.7-10.0] versus 12.4 [95%CI, 10.3-13.4] months, respectively; HR, 1.58 [95%CI, 1.06-2.35]; P=.024). The FCGR3A and EGFR polymorphisms were not associated with PFS in patients treated without cetuximab. None of the polymorphisms were associated with the incidence of grades 2-3 skin toxicity.nnnCONCLUSIONnEGFR and FCGR3A germline polymorphisms are associated with PFS in KRAS wild-type mCRC patients treated with cetuximab, bevacizumab and chemotherapy.