Abstract P5-10-03: Audit of the accuracy of immunohistochemical (IHC) testing of HER2 negative status of breast cancer in the United Kingdom

Background: The analysis of the level and distribution of HER2 protein expressed by cancer cells (HER2 status) is of great clinical value in the management of breast cancer patients both for the determination of the prognosis of disease and for identification of those patients who are eligible for anti-HER2 therapy. Accurate assessment of the HER2 status is essential for identifying patients which will benefit from HER2 targeted therapy. HER2 status in the UK is established using a two tier strategy with IHC as the initial test and subsequent reflex of equivocal results to in situ hybridization (ISH). IHC staining of the HER2 protein is graded as 0, 1+, 2+ or 3+ dependent upon the intensity of staining, cellular localisation and the percentage

of cells positive in accordance with CAP/ASCO and UK guidelines. HER2 3+ cases are considered as positive, with HER2 2+ cases (equivocal) retested by ISH to ascertain the gene amplification status. Cases that are scored as 0 and 1+ by IHC have no additional testing and are classed as negative. The literature indicates that a subset of these IHC negative cases show HER2 gene amplification by FISH (range 1.1-11.5%). The aim of this audit is to evaluate the discordance rate of HER2 IHC negative,

FISH positive breast cancer in the UK, with a secondary objective to resolve if this is related to the choice of antibody and assay platform used.

Materials and methods: This audit selected a total of 600 sequential cases reported as HER2 negative on IHC, from three UK reference centres receiving cases from 29 different hospitals. The cases were given a unique identifying number and annonymised. Each of the three centres used a different IHC method for frontline HER2 testing with centre one using HercepTestTM (DAKO), centre two Pathway 4B5 (Roche), and centre three, Oracle (Leica Microsystems). HER2 gene amplification status was determined using dual colour FISH analysis, PathVysion (ABBOTT) fluorescence ISH (FISH)

in a single centre to provide standardised methodology and assessment. HER2 was classed as amplified when the HER2/CEP 17 ratio was two or greater in accordance with UK guidelines. All cases which showed discordance between IHC and FISH were re-tested with each of the HER2 IHC platforms to discover whether these are truly discordant results or if the discrepancy is a consequence of the choice of antibody.

Results: 16/600 (2.8%) unequivocal HER2 gene amplification (mean ratio >2.0) whilst 8/600 (1.2%) had borderline amplification status(mean ratio = or <2.0). The overall assay specific discordance rates were 3.0% (HercepTest), 2.5% (4B5) and 3.0% (Oracle), respectively.

Conclusion: The observed level of discordance is well within the range of discordance rates reported by previous studies. The discrepancies could be due to inadequate quality fixation and/or inadequate sensitivity of the assay platforms used, or under scoring. A detailed analysis of possible assay related source of discrepancy is currently underway by repeating the analyses of the 24 discordant cases using like for like three assay platforms at an independent expert centre.

Citation Format: Bharat Jasani, Fiona Campbell, Phillapa Jones, Jane Gilbert, James Dowd, Keith Miller, Merdol Ibrahim, Ian Ellis, Emma Hurley, Mary Falzon, Barrett-Lee Peter, Jane Starczynski. Audit of the accuracy of immunohistochemical (IHC) testing of HER2 negative status of breast cancer in the United Kingdom [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-10-03.

A feasibility study testing four hypotheses with phase II outcomes in advanced colorectal cancer (MRC FOCUS3): a model for randomised controlled trials in the era of personalised medicine?

BACKGROUND

Molecular characteristics of cancer vary between individuals. In future, most trials will require assessment of biomarkers to allocate patients into enriched populations in which targeted therapies are more likely to be effective. The MRC FOCUS3 trial is a feasibility study to assess key elements in the planning of such studies.

PATIENTS AND METHODS

Patients with advanced colorectal cancer were registered from 24 centres between February 2010 and April 2011. With their consent, patients' tumour samples were analysed for KRAS/BRAF oncogene mutation status and topoisomerase 1 (topo-1) immunohistochemistry. Patients were then classified into one of four molecular strata; within each strata patients were randomised to one of two hypothesis-driven experimental therapies or a common control arm (FOLFIRI chemotherapy). A 4-stage suite of patient information sheets (PISs) was developed to avoid patient overload.

RESULTS

A total of 332 patients were registered, 244 randomised. Among randomised patients, biomarker results were provided within 10 working days (w.d.) in 71%, 15 w.d. in 91% and 20 w.d. in 99%. DNA mutation analysis was 100% concordant between two laboratories. Over 90% of participants reported excellent understanding of all aspects of the trial. In this randomised phase II setting, omission of irinotecan in the low topo-1 group was associated with increased response rate and addition of cetuximab in the KRAS, BRAF wild-type cohort was associated with longer progression-free survival.

CONCLUSIONS

Patient samples can be collected and analysed within workable time frames and with reproducible mutation results. Complex multi-arm designs are acceptable to patients with good PIS. Randomisation within each cohort provides outcome data that can inform clinical practice.

Critical research gaps and translational priorities for the successful prevention and treatment of breast cancer

INTRODUCTION

Breast cancer remains a significant scientific, clinical and societal challenge. This gap analysis has reviewed and critically assessed enduring issues and new challenges emerging from recent research, and proposes strategies for translating solutions into practice.

METHODS

More than 100 internationally recognised specialist breast cancer scientists, clinicians and healthcare professionals collaborated to address nine thematic areas: genetics, epigenetics and epidemiology; molecular pathology and cell biology; hormonal influences and endocrine therapy; imaging, detection and screening; current/novel therapies and biomarkers; drug resistance; metastasis, angiogenesis, circulating tumour cells, cancer 'stem' cells; risk and prevention; living with and managing breast cancer and its treatment. The groups developed summary papers through an iterative process which, following further appraisal from experts and patients, were melded into this summary account.

RESULTS

The 10 major gaps identified were: (1) understanding the functions and contextual interactions of genetic and epigenetic changes in normal breast development and during malignant transformation; (2) how to implement sustainable lifestyle changes (diet, exercise and weight) and chemopreventive strategies; (3) the need for tailored screening approaches including clinically actionable tests; (4) enhancing knowledge of molecular drivers behind breast cancer subtypes, progression and metastasis; (5) understanding the molecular mechanisms of tumour heterogeneity, dormancy, de novo or acquired resistance and how to target key nodes in these dynamic processes; (6) developing validated markers for chemosensitivity and radiosensitivity; (7) understanding the optimal duration, sequencing and rational combinations of treatment for improved personalised therapy; (8) validating multimodality imaging biomarkers for minimally invasive diagnosis and monitoring of responses in primary and metastatic disease; (9) developing interventions and support to improve the survivorship experience; (10) a continuing need for clinical material for translational research derived from normal breast, blood, primary, relapsed, metastatic and drug-resistant cancers with expert bioinformatics support to maximise its utility. The proposed infrastructural enablers include enhanced resources to support clinically relevant in vitro and in vivo tumour models; improved access to appropriate, fully annotated clinical samples; extended biomarker discovery, validation and standardisation; and facilitated cross-discipline working.

CONCLUSIONS

With resources to conduct further high-quality targeted research focusing on the gaps identified, increased knowledge translating into improved clinical care should be achievable within five years.

HER2/neu gene determination in women screened for breast carcinoma: how screening programs reduce the skyrocketing cost of targeted therapy

Few data on Human Epidermal Growth Factor Receptor 2 (HER2)-positive breast carcinomas have been reported for screen-detected breast carcinoma. Assessing the impact of a targeted intervention with anti-HER2 inhibitors on costs is required in order to plan for better strategies in screening programs. A total of 54,472 women were screened and 323 cases were found to be invasive cancer. We performed immunophenotypical-fluorescent in situ hybridization (FISH) analysis. Among 153 evaluable breast carcinomas, tumours displayed a 3+ scoring status 3+ in 16 (10%), 2+ in 12 (8%), 1+ in 29 (19%) and 0 in 96 (63%) of cases, respectively. All 3+ HER2+ cases and 2/12 2+ (17%) cases exhibited HER2/neu gene amplification, the remaining cases did not. In contrast to the higher incidence reported at the population level, 20-30% HER2-positive cases for metastatic carcinomas, and only 11% of the screen-detected breast carcinomas displayed HER2/neu gene amplification. Breast cancer detection by screening programs hijacks the skyrocketing cost of the use of targeted therapy in HER2-positive carcinoma.

Circulating HER2 Extracellular Domain: A Specific and Quantitative Biomarker of Prognostic Value in all Breast Cancer Patients?

The HER2 oncoprotein has emerged as an essential biomarker in the treatment of breast cancer patients. Once the primary breast cancer is removed, there is an increasing need to detect breast cancer recurrence as early as possible with the hope that earlier intervention with new anti-HER2 therapies will improve quality of life and increase overall survival. Numerous publications have shown that increasing blood levels of circulating HER2 is an early indicator of progression, particularly in HER2-positive patients and that the rise and fall parallels the clinical course of disease and independent of therapy. Many studies show that the HER2 status of the primary tumor may not fully and accurately reflect the HER2 status of recurrent cancer. Thus, elevated serum HER2 levels may be an early signal of the emergence of a HER2-positive metastatic tumor and therefore alert the physician to re-assess HER2 status using a tissue test.

Somatic profiling of the epidermal growth factor receptor pathway in tumors from patients with advanced colorectal cancer treated with chemotherapy ± cetuximab

PURPOSE

To study the somatic molecular profile of the EGF receptor (EGFR) pathway in advanced colorectal cancer, its relationship to prognosis, the site of the primary and metastases, and response to cetuximab.

EXPERIMENTAL DESIGN

We used Sequenom and Pyrosequencing for high-throughput somatic profiling of the EGFR pathway in 1,976 tumors from patients with advanced colorectal cancer from the COIN trial (oxaliplatin and fluoropyrimidine chemotherapy ± cetuximab). Correlations between mutations, clinicopathologic, response, and survival data were carried out.

RESULTS

Sequenom and Pyrosequencing had 99.0% (9,961/10,063) genotype concordance. We identified 13 different KRAS mutations in 42.3% of advanced colorectal cancers, 2 BRAF mutations in 9.0%, 4 NRAS mutations in 3.6%, and 5 PIK3CA mutations in 12.7%. 4.2% of advanced colorectal cancers had microsatellite instability (MSI). KRAS and PIK3CA exon 9, but not exon 20, mutations cooccurred (P = 8.9 × 10(-4)) as did MSI and BRAF mutations (P = 5.3 × 10(-10)). KRAS mutations were associated with right colon cancers (P = 5.2 × 10(-5)) and BRAF mutations with right (P = 7.2 × 10(-5)) and transverse colon (P = 9.8 × 10(-6)) cancers. KRAS mutations were associated with lung-only metastases (P = 2.3 × 10(-4)), BRAF mutations with peritoneal (P = 9.2 × 10(-4)) and nodal-only (P = 3.7 × 10(-5)) metastases, and MSI (BRAF(WT)) with nodal-only metastases (P = 2.9 × 10(-4)). MSI (BRAF(WT)) was associated with worse survival (HR = 1.89, 95% CI 1.30-2.76, P = 8.5 × 10(-4)). No mutations, subsets of mutations, or MSI status were associated with response to cetuximab.

CONCLUSIONS

Our data support a functional cooperation between KRAS and PIK3CA in colorectal tumorigenesis and link somatic profiles to the sites of metastases. MSI was associated with poor prognosis in advanced disease, and no individual somatic profile was associated with response to cetuximab in COIN.

The identification of a small but significant subset of patients still targetable with anti-HER2 inhibitors when affected by triple negative breast carcinoma

PURPOSE

Triple (ER-, PR-, HER2-) negative breast carcinoma lack targeted therapies, making this group of tumors difficult to treat. By definition, the lack of HER2 expression means a case scoring 0 or 1+ after immunophenotypical analysis and makes the patients avoiding therapeutical chances with anti-HER2 inhibitors. We sought to recruit from a group of triple negative breast carcinoma, patients eligible for effective personalized targeted therapy with anti-HER therapies on the basis of their HER2 gene status.

METHODS

135 patients diagnosed with IHC triple negative breast carcinoma were studied. Whole tissue sections were used for in situ hybridization analysis.

RESULTS

8/100 (8 %) of ductal-type triple negative breast carcinoma presented Her-2/neu gene amplification versus 2/35 (5.7 %) non-ductal triple negative breast carcinoma. Three cases showed a ratio 2.5. One case showed Her-2/neu heterogeneous gene amplification, ratio 2.3. The other six showed from 7 to 8 absolute Her-2/neu gene copy number. Two cases staged pT1c, and eight cases staged pT2. Eight cases graded G3 and two cases G2.

CONCLUSION

(1) Eight percentage of ductal and 5.7 % non-ductal-type triple negative breast carcinoma present Her-2/neu gene amplification, (2) the standard diagnostic flowchart "do not FISH in 0-1+ (HER2-) breast carcinoma" should be replaced by "do FISH in triple (ER-, PR-, HER2-) negative breast carcinoma," to avoid loss of therapeutical chances in a cohort of such a patients, (3) we demonstrated the identification of a small but significant subset of patients targetable with anti-HER2 inhibitors, giving patients affected by (ex)triple negative breast carcinoma new personalized therapeutical chances.

Use of epiregulin (EREG) and amphiregulin (AREG) gene expression to predict response to cetuximab (cet) in combination with oxaliplatin (Ox) and 5FU in the first-line treatment of advanced colorectal cancer (aCRC)

32

Background: Previous data suggests the EGF ligands EREG/AREG may predict outcome of KRAS wt patients (pts) treated with cet in the chemo-refractory setting but this finding has not been previously reported from first line randomised trials. Methods: FFPE samples from primary tumours of pts in Arms A&B of the COIN trial of Ox fluoropyrimidine (Fp) +/- cet were analysed for EGFR IHC, KRAS/NRAS/BRAF mutation and EREG/AREG expression by RT-PCR. Ligand levels were assessed against baseline data, prognostic markers as uni/multivariate analyses and as predictive markers in wild type (wt) and mutant (mt) cohorts and separately by Fp backbone [capecitabine (CapOx) or 5FU (FOLFOX)]. Tests for interaction were performed with EREG/AREG continuous, using Flexible Parametric survival analysis. Results: 952/1630 (57%) of pts were evaluable for all parameters. High EREG/AREG levels were associated with KRAS wt (p<0.005), BRAF wt, absence of MSI and with primary tumour in left colon/rectum, presence of liver metastases, post randomisation radical surgery, high CEA (p<0.05) and ALKP. In the control arm, high EREG/AREG conferred a better prognosis among KRAS wt pts in a multivariate analysis. High EREG predicted for OS benefit from cet. treatment in KRAS wt pts, (n=525, p=0.017) and, separately, in pts treated with FOLFOX (n=310, p=0.021), with greatest effect in the “combined” subgroup (KRAS wt + FOLFOX, n=176, p=0.0042). Conversely a trend towards disbenefit was observed in KRAS wt pts treated with XELOX (n=349, p=0.14). Conclusions: The data suggest a prognostic effect of EREG/AREG in aCRC. The original hypothesis, that KRAS wt patients with high EREG expression have improved outcome with cet, is limited to patients treated with FOLFOX in the first-line setting. This data further suggests that capecitabine in combination with oxaliplatin and cetuximab produces a sub-optimal outcome.

Relative Prognostic Value of Human Epidermal Growth Factor Receptor 2 (HER2) Expression in Operable Oesophagogastric Cancer

Aims. The aim of this study was to determine the prognostic significance of HER2 receptor expression in operable oesophagogastric adenocarcinoma. Methods. Eighty-five consecutive patients diagnosed with oesophagogastric adenocarcinoma [18 oesophageal (OC), 32 junctional (JC) and 35 gastric (GC)] undergoing potentially curative resection were studied retrospectively. Immunohistochemistry was used to determine HER2 status at endoscopic biopsy and resection specimen. The primary outcome measure was survival. Results. Twenty (24%) patients had HER2 positive tumours which was commoner in JC (14/32, 44% versus 2/18, 11% in OC and 4/35, 11% in GC, P = 0.003). The sensitivity, specificity, positive and negative predictive values of HER2 status at endoscopic biopsy were 56%, 93%, 63%, 91% respectively (weighted Kappa = 0.504, P < 0.0001). Five-year survival in OC HER2 positive negative was 100% and 36% (P = 0.167) compared with 14% and 44% (P = 0.0726) in JC and 50% and 46% (P = 0.942) in GC respectively. Conclusions. Endoscopic biopsy had a high specificity and negative predictive value in determining HER2 status. Patients with JC had a significantly higher rate of HER2 overexpression and this was associated with a nonsignificant poorer survival trend. A larger study is needed to confirm these findings because of the implications for neoadjuvant and adjuvant chemotherapy regimens.

Mesothelioma not associated with asbestos exposure

CONTEXT

Despite asbestos being identified as the single most important cause of malignant mesothelioma, the tumor is known to occur in only 10% to 20% of heavily exposed individuals. In addition, about 20% of the patients have no history of asbestos exposure even after detailed assessment. Therefore, there has been speculation for some time that asbestos alone may not be sufficient to cause mesothelioma and that other factors may be involved either as cocarcinogens or as independent mechanisms of cancer causation.

OBJECTIVE

To give a brief review of nonasbestos fiber erionite and therapeutic radiation as 2 established examples of asbestos-independent mechanisms, of the potential emerging role of man-made fibers such as carbon nanotubes, and of polyoma virus SV40 (simian virus 40) as a potential example of the cocarcinogenic mode of involvement.

DATA SOURCES

Relevant recent literature has been surveyed to portray and provide the evidence in favor of the examples.

CONCLUSIONS

Erionite has emerged as the most important example of nonasbestos-mediated cause of mesothelioma in regions such as Turkey where exposure to this type of fiber is highly prevalent. Recently, the polyoma virus SV40 has been unexpectedly discovered as an effective cocarcinogen of asbestos in the causation of animal mesothelioma, though despite considerable research, its potential role in human mesothelioma remains unproven.

HER2 gene amplification in breast cancer: a rogues' gallery of challenging diagnostic cases: UKNEQAS interpretation guidelines and research recommendations

International and national guidelines highlight the importance of accuracy, reproducibility, and quality control of in situ hybridization (ISH) methods for testing breast carcinomas. However, few guidelines cover the reporting of ISH cases with "unusual" signal patterns, including, eg, heterogeneity and loss of chromosome enumeration probe or gene signals. These cases are, in fact, relatively frequent, and there is a need for developing evidence- or consensus-based reporting guidelines to ensure consistency of treatment. Following an audit of cases from a single center (including >1,700 cases) we show that approximately 10% of ISH results reflect unusual signal patterns. We illustrate the most common of these patterns and provide reporting guidelines for diagnosticians and recommendations for future research. Our goal is to ensure that in the future such "rogues" are reported in a consistent manner that, ultimately, will be supported by molecular and biochemical evidence.

FOCUS 3: A study to determine the feasibility of molecular selection of therapy using K-RAS, B-RAF, and topo-1 in patients with advanced colorectal cancer (ACRC)

563

Background: Molecular characteristics of cancer vary between individuals. In future increasing numbers of trials will require assessment of biomarkers in order to allocate patients into enriched populations in which targeted therapies are more likely to be effective. The FOCUS 3 trial is a feasibility study to assess whether tumour samples could be collected from referring hospitals’ pathology departments, sent to designated reference laboratories for biomarker evaluation, and results provided to oncologists within 10 working days.

Methods: Patients with ACRC, fit for chemotherapy, were registered from 24 centres between 02.10 and 04.11. Following consent, paraffin embedded tumour samples were sent to Cardiff or Leeds for analysis of topoisomerase 1 (topo-1) by immunohistochemistry and of KRAS and BRAF mutation status, and results were forwarded to the MRC CTU. Patients were classified into 1 of 4 molecular strata, which determined the set of 2 hypothesis driven experimental therapies they could be randomised to in addition to control chemotherapy (irinotecan + 5FU). At this stage eligibility was reconfirmed and consent for randomisation obtained.

Results: 332 patients were registered to participate in FOCUS 3. Biomarker results were provided to oncologists within 10 working days (wd) in 71%, within 15 wd in 91% and within 20 wd in 99% patients. A 4 stage suite of patient information sheets (PIS) was designed and implemented to avoid patient overload; separate information sheets were provided to patients at stages during the consent process and patient understanding was assessed. 93% of eligible patients gave consent to randomisation. KRAS mutation was detected in 88 (36%), BRAF in 15 (6%), 2 patients had both mutations and 133 were double wildtype. 77% of patients were high (2-3), 19% low (0-1) and 4% inconclusive for topo-1. Tumour response and toxicity results for the 244 randomised patients will be presented.

Conclusions: Patient samples can be collected and analysed at designated reference laboratories within acceptable timeframes. Multi-arm designs can be made acceptable to patients through good PIS, ensured by patient and carer input into their design.

Adenosine A2A and A2B receptor expression in neuroendocrine tumours: potential targets for therapy

The clinical management of neuroendocrine tumours is complex. Such tumours are highly vascular suggesting tumour-related angiogenesis. Adenosine, released during cellular stress, damage and hypoxia, is a major regulator of angiogenesis. Herein, we describe the expression and function of adenosine receptors (A(1), A(2A), A(2B) and A(3)) in neuroendocrine tumours. Expression of adenosine receptors was investigated in archival human neuroendocrine tumour sections and in two human tumour cell lines, BON-1 (pancreatic) and KRJ-I (intestinal). Their function, with respect to growth and chromogranin A secretion was carried out in vitro. Immunocytochemical data showed that A(2A) and A(2B) receptors were strongly expressed in 15/15 and 13/18 archival tumour sections. Staining for A(1) (4/18) and A(3) (6/18) receptors was either very weak or absent. In vitro data showed that adenosine stimulated a three- to fourfold increase in cAMP levels in BON-1 and KRJ-1 cells. The non-selective adenosine receptor agonist (adenosine-5'N-ethylcarboxamide, NECA) and the A(2A)R agonist (CGS21680) stimulated cell proliferation by up to 20-40% which was attenuated by A(2B) (PSB603 and MRS1754) and A(2A) (SCH442416) receptor selective antagonists but not by the A(1) receptor antagonist (PSB36). Adenosine and NECA stimulated a twofold increase in chromogranin A secretion in BON-1 cells. Our data suggest that neuroendocrine tumours predominantly express A(2A) and A(2B) adenosine receptors; their activation leads to increased proliferation and secretion of chromogranin A. Targeting adenosine signal pathways, specifically inhibition of A(2) receptors, may thus be a useful addition to the therapeutic management of neuroendocrine tumours.

HER2 testing in the UK: recommendations for breast and gastric in-situ hybridisation methods

These guidelines supplement existing guidelines on HER2 testing by immunohistochemistry and in-situ hybridisation(ISH) methods in the UK. They provide a specific focus on aspects of guidance relevant to HER2 ISH testing methods, both fluorescent and chromogenic. They are formulated to give advice on methodology, interpretation and quality control for ISH-based testing of HER2 status in common tumour types, including both breast and gastric tumours. The aim is to ensure that all ISH-based testing is accurate, reliable and timely.

Addition of cetuximab to oxaliplatin-based first-line combination chemotherapy for treatment of advanced colorectal cancer: results of the randomised phase 3 MRC COIN trial

BACKGROUND

In the Medical Research Council (MRC) COIN trial, the epidermal growth factor receptor (EGFR)-targeted antibody cetuximab was added to standard chemotherapy in first-line treatment of advanced colorectal cancer with the aim of assessing effect on overall survival.

METHODS

In this randomised controlled trial, patients who were fit for but had not received previous chemotherapy for advanced colorectal cancer were randomly assigned to oxaliplatin and fluoropyrimidine chemotherapy (arm A), the same combination plus cetuximab (arm B), or intermittent chemotherapy (arm C). The choice of fluoropyrimidine therapy (capecitabine or infused fluouroracil plus leucovorin) was decided before randomisation. Randomisation was done centrally (via telephone) by the MRC Clinical Trials Unit using minimisation. Treatment allocation was not masked. The comparison of arms A and C is described in a companion paper. Here, we present the comparison of arm A and B, for which the primary outcome was overall survival in patients with KRAS wild-type tumours. Analysis was by intention to treat. Further analyses with respect to NRAS, BRAF, and EGFR status were done. The trial is registered, ISRCTN27286448.

FINDINGS

1630 patients were randomly assigned to treatment groups (815 to standard therapy and 815 to addition of cetuximab). Tumour samples from 1316 (81%) patients were used for somatic molecular analyses; 565 (43%) had KRAS mutations. In patients with KRAS wild-type tumours (arm A, n=367; arm B, n=362), overall survival did not differ between treatment groups (median survival 17·9 months [IQR 10·3-29·2] in the control group vs 17·0 months [9·4-30·1] in the cetuximab group; HR 1·04, 95% CI 0·87-1·23, p=0·67). Similarly, there was no effect on progression-free survival (8·6 months [IQR 5·0-12·5] in the control group vs 8·6 months [5·1-13·8] in the cetuximab group; HR 0·96, 0·82-1·12, p=0·60). Overall response rate increased from 57% (n=209) with chemotherapy alone to 64% (n=232) with addition of cetuximab (p=0·049). Grade 3 and higher skin and gastrointestinal toxic effects were increased with cetuximab (14 vs 114 and 67 vs 97 patients in the control group vs the cetuximab group with KRAS wild-type tumours, respectively). Overall survival differs by somatic mutation status irrespective of treatment received: BRAF mutant, 8·8 months (IQR 4·5-27·4); KRAS mutant, 14·4 months (8·5-24·0); all wild-type, 20·1 months (11·5-31·7).

INTERPRETATION

This trial has not confirmed a benefit of addition of cetuximab to oxaliplatin-based chemotherapy in first-line treatment of patients with advanced colorectal cancer. Cetuximab increases response rate, with no evidence of benefit in progression-free or overall survival in KRAS wild-type patients or even in patients selected by additional mutational analysis of their tumours. The use of cetuximab in combination with oxaliplatin and capecitabine in first-line chemotherapy in patients with widespread metastases cannot be recommended.

FUNDING

Cancer Research UK, Cancer Research Wales, UK Medical Research Council, Merck KGgA.

Abstract 4919: Multiplexed EGFR signaling pathway analysis in FFPE tissue using quantitative mass spectrometry

The epidermal growth factor receptor (EGFR) is a drug target for both small molecule and antibody therapeutics and has been approved in non small-cell lung carcinoma (NSCLC) and colorectal carcinoma (CRC) among other indications. These drugs block receptor signaling though blockade of the tyrosine kinase domain, or through inhibition of ligand binding. Current genomic tests measure receptor amplification, RNA levels, the mutation status of receptor or pathway molecules (EGFR or kRAS mutations) but no current assay can directly assess the activation state of the EGFR or its downstream signaling pathway components. Indeed, the EGFR mutation positive NSCLC tumors (thought to be constitutively active) show a high response rate to TKI therapy, but the many non responders (50% or more) demonstrate the limitation of genomic analysis.

Since activation of EGFR is necessary for the response to these targeted agents, it is critical to measure what levels of receptor activation and downstream signaling determines tumor responsiveness to EGFR targeted therapies in these patients. For this reason, we have developed a panel of new diagnostic assays which measure the activation of the EGFR and key downstream signaling proteins through quantitation of the phosphorylation state of these proteins. These assays are based on the Liquid Tissue®-SRM technology platform. This approach enables relative and absolute quantification of proteins and their phosphorylation status directly in formalin fixed paraffin embedded (FFPE) tissue.

We preclinically validated the multiplexed Liquid Tissue® phospho-SRM assay on formalin fixed EGF stimulated A431 cells. We followed up these in vitro studies with phospho-SRM analysis of FFPE NSCLC xenograft explants where extensive independent histopathologic and molecular characterization had been performed, allowing us to benchmark our phospho-SRM analysis with standard diagnostic analyses.

We have now extended these quantitation studies by measuring the expression of EGFR and phospho-EGFR in FFPE tissues obtained from relevant human clinical trial cohorts – Gefitinib treated NSCLC and Cetuximab treated CRC. It is hoped that we will be able to correlate EGFR expression, activation and signaling in these tumors with responsiveness to EGFR targeted therapy, and to validate this assay for use as a companion diagnostic to guide therapy in both NSCLC and CRC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4919. doi:10.1158/1538-7445.AM2011-4919

Epidermal growth factor receptor (EGFR) as a predictive and prognostic marker in patients with advanced colorectal cancer (aCRC): The MRC COIN trial experience

359

Background: KRAS mutation has been shown to be a more effective (though negative) biomarker for selection of patients for EGFR targeted therapy in aCRC. However, positive EGFR immunohistochemistry (IHC) remains a license requirement and was an inclusion criterion in most trials to date. The MRC COIN trial recruited 2445 pts into 3 arms of oxaliplatin + fluoropyrimidine +/- cetuximab without prior EGFR assessment. This trial provides a unique opportunity to definitively examine the role of EGFR IHC as prognostic and predictive marker and potentially the evidence required to remove this assessment from the license for this drug.

Methods: Formalin-fixed paraffin embedded (FFPE) tissue was stained retrospectively for EGFR using Dako kit in a national reference lab. Results were assessed by 3 reviewers (BJ, SS, RA) using digital imaging software in a blinded fashion, then by BJ/SS providing consensus for discrepancies. EGFR scoring was assessed as a prognostic variable in association with selected patient, tumor and biochemical data. Cut off points examined for +ve vs -ve tumours, in terms of total tumour cells demonstrating membrane staining, were: 0% vs >0%; <10% vs ≥10%; <20% vs ≥20%.

Results: EGFR IHC was adequately assessed for 1621 pts (66% of randomised), 22% were negative (0%) and 78% positive (>0%), balanced across arms. EGFR was not prognostic for PFS within KRAS wt pts at the standardized cut off point 0% vs >0% HR=1.11 95% CI 0.91-1.36 p=0.31 but was at <10% vs ≥10% (HR=1.27 95% CI 1.07-1.52 p=0.008) this was robust to other prognostic variables. No effect was seen for overall response or survival. There was no prognostic effect for the KRAS mutant group. In the 1065 assessable pts randomised to +/- cetuximab, no evidence of EGFR IHC as a predictive marker for response or survival outcomes was observed for the addition of cetuximab to chemotherapy (OS HR=1.11 95% CI 0.70-1.75 p=0.66; PFS HR=0.95 95% CI 0.64-1.43 p=0.82).

Conclusions: Extensive assessment of samples from this trial suggest a role for EGFR IHC as a prognostic marker in KRAS wt aCRC but refute the predictive value embedded within the licence for cetuximab used in combination with chemo in first-line therapy.

[Table: see text]