Associations between AI-Assisted Tumor Amphiregulin and Epiregulin IHC and Outcomes from Anti-EGFR Therapy in the Routine Management of Metastatic Colorectal Cancer

PURPOSE

High tumor production of the EGFR ligands, amphiregulin (AREG) and epiregulin (EREG), predicted benefit from anti-EGFR therapy for metastatic colorectal cancer (mCRC) in a retrospective analysis of clinical trial data. Here, AREG/EREG IHC was analyzed in a cohort of patients who received anti-EGFR therapy as part of routine care, including key clinical contexts not investigated in the previous analysis.

EXPERIMENTAL DESIGN

Patients who received panitumumab or cetuximab ± chemotherapy for treatment of RAS wild-type mCRC at eight UK cancer centers were eligible. Archival formalin-fixed paraffin-embedded tumor tissue was analyzed for AREG and EREG IHC in six regional laboratories using previously developed artificial intelligence technologies. Primary endpoints were progression-free survival (PFS) and overall survival (OS).

RESULTS

A total of 494 of 541 patients (91.3%) had adequate tissue for analysis. A total of 45 were excluded after central extended RAS testing, leaving 449 patients in the primary analysis population. After adjustment for additional prognostic factors, high AREG/EREG expression (n = 360; 80.2%) was associated with significantly prolonged PFS [median: 8.5 vs. 4.4 months; HR, 0.73; 95% confidence interval (CI), 0.56-0.95; P = 0.02] and OS [median: 16.4 vs. 8.9 months; HR, 0.66 95% CI, 0.50-0.86; P = 0.002]. The significant OS benefit was maintained among patients with right primary tumor location (PTL), those receiving cetuximab or panitumumab, those with an oxaliplatin- or irinotecan-based chemotherapy backbone, and those with tumor tissue obtained by biopsy or surgical resection.

CONCLUSIONS

High tumor AREG/EREG expression was associated with superior survival outcomes from anti-EGFR therapy in mCRC, including in right PTL disease. AREG/EREG IHC assessment could aid therapeutic decisions in routine practice. See related commentary by Randon and Pietrantonio, p. 4021.

FOCUS4 biomarker laboratories: from the benefits to the practical and logistical issues faced during 6 years of centralised testing

AIMS

FOCUS4 was a phase II/III umbrella trial, recruiting patients with advanced or metastatic colorectal cancer, between 2014 and 2020. Molecular profiling of patients' formalin-fixed, paraffin-embedded tumour blocks was undertaken at two centralised biomarker laboratories (Leeds and Cardiff), and the results fed directly to the Medical Research Council Clinical Trials Unit, and used for subsequent randomisation. Here the laboratories discuss their experiences.

METHODS

Following successful tumour content assessment, blocks were sectioned for DNA extraction and immunohistochemistry (IHC). Pyrosequencing was initially used to determine tumour mutation status (KRAS, NRAS, BRAF and PIK3CA), then from 2018 onwards, next-generation sequencing was employed to allow the inclusion of TP53. Protein expression of MLH1, MSH2, MSH6, PMS2 and pTEN was determined by IHC. An interlaboratory comparison programme was initiated, allowing sample exchanges, to ensure continued assay robustness.

RESULTS

1291 tumour samples were successfully analysed. Assay failure rates were very low; 1.9%-3.3% for DNA sequencing and 0.9%-1.3% for IHC. Concordance rates of >98% were seen for the interlaboratory comparisons, where a result was obtained by both laboratories.

CONCLUSIONS

Practical and logistical problems were identified, including poor sample quality and difficulties with sample anonymisation. The often last-minute receipt of a sample for testing and a lack of integration with National Health Service mutation analysis services were challenging. The laboratories benefitted from both pretrial validations and interlaboratory comparisons, resulting in robust assay development and provided confidence during the implementation of new sequencing technologies. We conclude that our centralised approach to biomarker testing in FOCUS4 was effective and successful.

GBMdeconvoluteR accurately infers proportions of neoplastic and immune cell populations from bulk glioblastoma transcriptomics data

BACKGROUND

Characterizing and quantifying cell types within glioblastoma (GBM) tumors at scale will facilitate a better understanding of the association between the cellular landscape and tumor phenotypes or clinical correlates. We aimed to develop a tool that deconvolutes immune and neoplastic cells within the GBM tumor microenvironment from bulk RNA sequencing data.

METHODS

We developed an IDH wild-type (IDHwt) GBM-specific single immune cell reference consisting of B cells, T-cells, NK-cells, microglia, tumor associated macrophages, monocytes, mast and DC cells. We used this alongside an existing neoplastic single cell-type reference for astrocyte-like, oligodendrocyte- and neuronal progenitor-like and mesenchymal GBM cancer cells to create both marker and gene signature matrix-based deconvolution tools. We applied single-cell resolution imaging mass cytometry (IMC) to ten IDHwt GBM samples, five paired primary and recurrent tumors, to determine which deconvolution approach performed best.

RESULTS

Marker-based deconvolution using GBM-tissue specific markers was most accurate for both immune cells and cancer cells, so we packaged this approach as GBMdeconvoluteR. We applied GBMdeconvoluteR to bulk GBM RNAseq data from The Cancer Genome Atlas and recapitulated recent findings from multi-omics single cell studies with regards associations between mesenchymal GBM cancer cells and both lymphoid and myeloid cells. Furthermore, we expanded upon this to show that these associations are stronger in patients with worse prognosis.

CONCLUSIONS

GBMdeconvoluteR accurately quantifies immune and neoplastic cell proportions in IDHwt GBM bulk RNA sequencing data and is accessible here: https://gbmdeconvoluter.leeds.ac.uk.

Artificial intelligence-assisted evaluation of tumor infiltrating CD3+ and CD8+ T cells for prognostication and prediction of benefit from adjuvant chemotherapy in early stage colorectal cancer (CRC): A retrospective analysis of the QUASAR trial

204

Background: High CD3+ (all) and CD8+ (cytotoxic) T cell densities in the core (CT) and invasive margin (IM) of primary CRCs have been shown to be associated with superior prognosis at all stages of disease. Their predictive effect on benefit from adjuvant chemotherapy in early stage CRC has not been tested. Methods: FFPE samples from participants (pts) in the QUASAR trial (adjuvant fluorouracil/folinic acid vs observation in stage 2/3 CRC) were analysed for CD3 and CD8 immunohistochemistry (IHC). Pathologists annotated the core and peritumor areas on digital slide images. Artificial intelligence (AI) algorithms delineated the CT and IM, and calculated the densities (cells/mm2) of each marker in each region (CD3-CT, CD3-IM, CD8-CT, CD8-IM). Pts were randomly partitioned into test and validation sets (1:1). In the test set, each measure’s prognostic effect on recurrence-free interval (RFI) (primary endpoint), colorectal cancer mortality (CCM) and overall survival (OS) in each trial arm was assessed. Maximum likelihoods methods were used to develop optimal cut-points. Analyses were repeated in the validation set. Analysis of 425 pts in each set would give > 95% power (α = 0.05, 2-sided) to detect a twofold difference in recurrence risk. In predictive analyses, 2-year recurrence rate was the primary outcome; biomarker-treatment interactions were assessed. Results: Tumor tissue from 868 pts (797 [92%] stage 2; 531 [61%] colon) was analysed, with evaluable results for CD3-CT in 851 (98.0%), CD3-IM in 833 (96.0%), CD8-CT in 849 (97.0%) and CD8-IM in 820 (94.5%) pts. In the test set, optimal cut-points of 318, 798, 81 and 186 cells/mm2 were defined for CD3-CT, CD3-IM, CD8-CT and CD8-IM respectively. The recurrence rate in the high-risk group was twice that in the low-risk group for all measures (CD3-CT: rate ratio [RR] 2.00, [95%CI 1.33-2.94], p = 0.0008; CD3-IM: 2.38, [1.59-3.57], p < 0.00001; CD8-CT: 2.17, [1.59-3.57], p = 0.0001; CD8-IM: 2.13 [1.43-3.23], p = 0.0001), which was closely replicated in the validation set (CD3-CT: RR 1.96, [1.30-2.94], p = 0.002; CD3-IM: 1.79, [1.18-2.70], p = 0.005; CD8-CT: 1.72, [1.18-2.56], p = 0.005; CD8-IM: 1.72 [1.15-2.56], p = 0.008). In multivariate analyses, prognostic effects were similar in colon and rectal cancers, and in stage 2 and 3 disease. CD3/8 counts were not predictive of benefit from adjuvant chemotherapy, with similar efficacy in the high and low risk groups. Conclusions: AI-assisted CD3 and CD8 counts were strongly associated with tumor recurrence rates. With no biomarker-treatment interactions, proportional reductions in recurrence with chemotherapy were similar in high and low-risk disease. Hence, numbers of high-risk patients needed to treat to prevent one recurrence were about half the number for low-risk patients.

A biomarker enrichment trial of anti-EGFR agents in right primary tumor location (rPTL), RAS wild-type (RAS-wt) advanced colorectal cancer (aCRC): ARIEL (ISRCTN11061442)

TPS3633

Background: Meta-analysis of 6 RCTs indicates that anti-EGFR agents are ineffective in rPTL RAS-wt aCRC (Arnold D, et al. Ann Oncol. 2017;28:1713-1729). However, data from the phase III PICCOLO and COIN trials suggest high tumor expression of the EGFR ligands, EREG and AREG, confers sensitivity to anti-EGFR agents in a subset of this population (Adams RA, et al. J Clin Oncol. 2012;30(30_suppl):32-32; Seligmann JF, et al. Ann Oncol. 2020;31:1021-1029). More data is needed before ligand assessment can be integrated into routine care: to date, EREG/AREG mRNA has only been assessed retrospectively, and feasibility of timely delivery of results must be demonstrated. The ARIEL trial aims to determine whether first-line chemotherapy plus cetuximab or panitumumab is more effective than chemotherapy alone in achieving early tumor shrinkage (ETS) after 8 weeks of treatment in patients (pts) with EREG/AREG-high rPTL RAS-wt aCRC. Methods: ARIEL is a multicentre, phase IV, open label, biomarker enrichment RCT. Pts with previously untreated rPTL RAS-wt (or RAS-unknown) aCRC are eligible for registration and EREG/AREG assessment using archival FFPE tumor tissue. Those confirmed as RAS-wt EREG/AREG-high (expression above 30th centile based on PICCOLO)3 are eligible for randomization to chemotherapy alone (fluoropyrimidine backbone plus irinotecan or oxaliplatin) vs chemotherapy (FOLFOX or FOLFIRI) plus anti-EGFR therapy (panitumumab or cetuximab) (options at physician’s discretion). Pts with EREG/AREG-low tumors are not eligible for randomization but may consent to translational research and follow-up. The primary endpoint is ETS at 8 weeks (≥30%, yes vs no). Secondary endpoints are depth of response at 16 weeks, overall survival, overall treatment utility, pt-reported quality of life, cost per QALY, pt acceptability of trial procedures, and safety. Pre-trial work-up included cross-validation of the EREG/AREG RT-qPCR assay at trial laboratories in Leeds and Birmingham, UK demonstrating reproducibility of biomarker results. Recruitment to an internal pilot phase is currently ongoing to demonstrate feasibility of timely delivery of biomarker results to sites (lower limit of 90% CI of mean result delivery time for first 20 pts must include 3 weeks). Mean monthly recruitment rate will be assessed at 18 months to determine likelihood of completion of the trial within the 3 year recruitment period. ARIEL is funded by the UK National Institute for Health Research (NIHR) and opened the first of 40 sites in February 2022. 440 pts will be registered for biomarker assessment in order to randomize 162 pts. All pts will be followed-up to 1 year post-randomisation, with a final assessment in all pts when the last pt has completed a year of follow-up (median 3.5 years). ARIEL is participating in the NIHR Associate PI scheme. Clinical trial information: 11061442.

Clinical and molecular characteristics and treatment outcomes of advanced right-colon, left-colon and rectal cancers: data from 1180 patients in a phase III trial of panitumumab with an extended biomarker panel

BACKGROUND

Primary tumour location (PTL) is being adopted by clinicians to guide treatment decisions in metastatic colorectal cancer (mCRC). Here we test PTL as a predictive marker for panitumumab efficacy, and examine its relationship with an extended biomarker profile. We also examine rectal tumours as a separate location.

PATIENTS AND METHODS

mCRC patients from the second-line PICCOLO trial of irinotecan versus irinotecan/panitumumab (IrPan). PTL was classified as right-PTL, left-PTL or rectal-PTL. PTL was assessed as a predictive biomarker for IrPan effect in RAS-wild-type (RAS-wt) patients (compared with irinotecan alone), then tested for independence alongside an extended biomarker profile (BRAF, epiregulin/amphiregulin (EREG/AREG) and HER3 mRNA expression).

RESULTS

PTL data were available for 1180 patients (98.5%), of whom 558 were RAS-wt. High HER3 expression was independently predictive of panitumumab overall survival improvement, but PTL and EREG/AREG were not. IrPan progression-free survival (PFS) improvement compared with irinotecan was seen in left-PTL [hazard ratio (HR) = 0.61, P = 0.002) but not right-PTL (HR = 0.98, P = 0.90) (interaction P = 0.05; RAS/BRAF-wt interaction P = 0.10), or in rectal-PTL (HR = 0.82, P = 0.20) (interaction P = 0.14 compared with left-PTL; RAS/BRAF-wt interaction P = 0.04). Patients with right-PTL and high EREG/AREG or HER3 expression, had IrPan PFS improvement (high EREG/AREG HR = 0.20, P = 0.04; high HER3 HR = 0.33, P = 0.10) compared with irinotecan. Similar effect was seen for rectal-PTL patients (high EREG/AREG HR = 0.44, P = 0.03; high HER3 HR = 0.34, P = 0.05).

CONCLUSIONS

RAS-wt patients with left-PTL are more likely to have panitumumab PFS advantage than those with right-PTL or rectal-PTL. However, an extended biomarker panel demonstrated significant heterogeneity in panitumumab PFS effect within a tumour location. AREG/EREG and HER3 mRNA expression identifies patients with right-PTL or rectal-PTL who achieve similar PFS effect with panitumumab as left-colon patients. Testing could provide a more reliable basis for clinical decision making. Further validation and development of these biomarkers is required to optimise routine patient care.

CLINICAL TRIAL REGISTRATION

ISRCTN identifier: ISRCTN93248876.

Shape Discrimination in Tropical Fish

Two experiments are reported using Egyptian mouthbreeders as subjects in which circle/square discriminations were attempted. In Experiment 1, using large stimuli in a maze type situation, no learning was shown by any of the six subjects. In Experiment II, using a conditioned operant technique of nose banging with smaller stimuli, some learning was shown by only one of the five fish. Rapid learning of other discriminations using the square or circle as negative stimuli was subsequently shown.

Preoperative chemoradiation with capecitabine, irinotecan and cetuximab in rectal cancer: significance of pre-treatment and post-resection RAS mutations

BACKGROUND

The influence of EGFR pathway mutations on cetuximab-containing rectal cancer preoperative chemoradiation (CRT) is uncertain.

METHODS

In a prospective phase II trial (EXCITE), patients with magnetic resonance imaging (MRI)-defined non-metastatic rectal adenocarinoma threatening/involving the surgical resection plane received pelvic radiotherapy with concurrent capecitabine, irinotecan and cetuximab. Resection was recommended 8 weeks later. The primary endpoint was histopathologically clear (R0) resection margin. Pre-planned retrospective DNA pyrosequencing (PS) and next generation sequencing (NGS) of KRAS, NRAS, PIK3CA and BRAF was performed on the pre-treatment biopsy and resected specimen.

RESULTS

Eighty-two patients were recruited and 76 underwent surgery, with R0 resection in 67 (82%, 90%CI: 73-88%) (four patients with clinical complete response declined surgery). Twenty-four patients (30%) had an excellent clinical or pathological response (ECPR). Using NGS 24 (46%) of 52 matched biopsies/resections were discrepant: ten patients (19%) gained 13 new resection mutations compared to biopsy (12 KRAS, one PIK3CA) and 18 (35%) lost 22 mutations (15 KRAS, 7 PIK3CA). Tumours only ever testing RAS wild-type had significantly greater ECPR than tumours with either biopsy or resection RAS mutations (14/29 [48%] vs 10/51 [20%], P=0.008), with a trend towards increased overall survival (HR 0.23, 95% CI 0.05-1.03, P=0.055).

CONCLUSIONS

This regimen was feasible and the primary study endpoint was met. For the first time using pre-operative rectal CRT, emergence of clinically important new resection mutations is described, likely reflecting intratumoural heterogeneity manifesting either as treatment-driven selective clonal expansion or a geographical biopsy sampling miss.

Gaining biomarker insights from existing stage II colorectal cancer (CRC) patient cohorts in the United Kingdom: Using real-world data to guide treatment decisions

614

Background: Trial data, while valuable, does not reflect the importance of a biomarker or treatment in the general population as trials generally exclude patients (pts) due to age or comorbidities. We used merged large population datasets to validate a linked anonymized stage II CRC pt cohort as representative of the population to identify the prognostic and predictive value of deficient mismatch repair (MMR) and a new biomarker Ga-interacting vesicle-associated protein (GIV). Methods: English national data on stage II CRC pts surgically treated from 2001-2015, n = 92,147, were analyzed for survival and clinicopathological parameters. Anonymized data were then linked to pathology and a subset of 405 unselected pts surgically treated from 1990-2003 at the Leeds Teaching Hospitals NHS Trust. These were investigated for 5 antibodies. 4 identified deficient MMR status and one was a new marker; GIV. Results: Population data vs the cohort of 405 pts showed a median age of 73 vs 74 yrs, M:F 55%:45% vs. 53%:47%. These are older than seen in most clinical trials and more reflective of the general stage II CRC population. The median survivals of 108 vs 92 months are as expected based on relative time periods covered. 374 patients yielded valid MMR status on immunohistochemistry (92%); 17% were dMMR and 83% were proficient. dMMR vs pMMR pts did not differ in age (median age 75 vs 74.5) or distribution of T3 (69% vs 66%), but were more likely to be female (71% vs 42%), sited in the right colon (76% vs 30%) and poorly differentiated (42% vs 8%). 11% of dMMR and 8% of pMMR received adjuvant chemotherapy in this cohort. GIV scoring status was also evaluated (405): 30% (121) were negative, 65% (264) positive and 5% (20) were not scored. Survival and risk scores by MMR and GIV status will be presented. Conclusions: Population based data has been created to validate the representativeness of a stage II biomarker cohort. This approach using large, population based data-sets provides opportunities to understand the generalizability of biomarker cohorts. The creation and expansion of such cohorts will more effectively validate existing and new biomarkers and treatments in real-world populations.

Combined Epiregulin and Amphiregulin Expression Levels as a Predictive Biomarker for Panitumumab Therapy Benefit or Lack of Benefit in Patients With RAS Wild-Type Advanced Colorectal Cancer

IMPORTANCE

RAS wild-type (wt) status is necessary but not sufficient for response to anti-epidermal growth factor receptor (EGFR) agents in advanced colorectal cancer (aCRC). RNA expression of EGFR ligands epiregulin (EREG) and amphiregulin (AREG) may correlate with EGFR-targeted therapy efficacy in aCRC, so may represent a much-needed additional predictive marker for these drugs.

OBJECTIVE

To examine a novel ligand model in a randomized clinical trial of panitumumab, irinotecan, and ciclosporin in colorectal cancer (PICCOLO) with with the a priori hypothesis that high tumor expression of either AREG or EREG would predict panitumumab therapy benefit in RAS-wt patients; and low expression, lack of efficacy.

DESIGN, SETTING, AND PARTICIPANTS

Prospectively planned retrospective biomarker study from the PICCOLO trial, which tested the addition of panitumumab to irinotecan therapy in patients with KRAS wt aCRC who experienced failure with prior fluoropyrimidine treatment. The analysis was conducted between 2012 and 2014. A predefined dichotomous model classified tumors as "high expressor" (either EREG or AREG in top tertile for messenger RNA level) or "low expressor" (neither EREG nor AREG in top tertile). Ligand expression was assessed as a prognostic and predictive biomarker. Expression of AREG/EREG and RAS and BRAF mutations were assessed in archival tumor tissue.

MAIN OUTCOMES AND MEASURES

Primary end point was progression-free survival (PFS); secondary end points were response rate and overall survival (OS).

RESULTS

Of the 696 PICCOLO trial patients in the irinotecan-vs-irinotecan with panitumumab randomization, 331 had sufficient tumor tissue available and measurement of ligand expression was successful in 323. High ligand expression was not prognostic for OS (hazard ratio [HR], 0.79 [95% CI, 0.58-1.09]; P = .15) or PFS (HR, 0.93 [95% CI, 0.68-1.27]; P = .64). The primary population had RAS wt aCRC (n = 220); for RAS wt patients with high ligand expression, median (interquartile range [IQR]) PFS was 8.3 [4.0-11.0] months (irinotecan with panitumumab) vs 4.4 [2.8-6.7] months (irinotecan alone); HR, 0.38 [95% CI, 0.24-0.61]; P < .001). In RAS wt patients with low ligand expression, median (IQR) PFS was 3.2 [2.7-8.1] months (irinotecan with panitumumab) vs 4.0 [2.7-7.5] months (irinotecan); HR, 0.93 [95% CI, 0.64-1.37]; P = .73; interaction test results were significant [P = .01]). Less marked effects were seen for response rate (interaction P = .17) and OS (interaction P = .11).

CONCLUSIONS AND RELEVANCE

High ligand expression is a predictive marker for panitumumab therapy benefit on PFS in RAS wt patients; conversely, patients with low ligand expression gained no benefit. The current "opt-in" strategy for anti-EGFR therapy in all patients with RAS wt aCRC should be questioned. Expression of EREG/AREG is a useful biomarker for anti-EGFR therapy; optimization for clinical use is indicated.

TRIAL REGISTRATION

isrctn Identifier: ISRCTN93248876.

HER2 overexpression and amplification as a potential therapeutic target in colorectal cancer: analysis of 3256 patients enrolled in the QUASAR, FOCUS and PICCOLO colorectal cancer trials

HER2 overexpression/amplification is linked to trastuzumab response in breast/gastric cancers. One suggested anti‐EGFR resistance mechanism in colorectal cancer (CRC) is aberrant MEK–AKT pathway activation through HER2 up‐regulation. We assessed HER2‐amplification/overexpression in stage II–III and IV CRC patients, assessing relationships to KRAS/BRAF and outcome. Pathological material was obtained from 1914 patients in the QUASAR stage II–III trial and 1342 patients in stage IV trials (FOCUS and PICCOLO). Tissue microarrays were created for HER2 immunohistochemistry. HER2‐amplification was assessed using FISH and copy number variation. KRAS/BRAF mutation status was assessed by pyrosequencing. Progression‐free survival (PFS) and overall survival (OS) data were obtained for FOCUS/PICCOLO and recurrence and mortality for QUASAR; 29/1342 (2.2%) stage IV and 25/1914 (1.3%) stage II–III tumours showed HER2 protein overexpression. Of the HER2‐overexpressing cases, 27/28 (96.4%) stage IV tumours and 20/24 (83.3%) stage II–III tumours demonstrated HER2 amplification by FISH; 41/47 (87.2%) also showed copy number gains. HER2‐overexpression was associated with KRAS/BRAF wild‐type (WT) status at all stages: in 5.2% WT versus 1.0% mutated tumours (p < 0.0001) in stage IV and 2.1% versus 0.2% in stage II–III tumours (p = 0.01), respectively. HER2 was not associated with OS or PFS. At stage II–III, there was no significant correlation between HER2 overexpression and 5FU/FA response. A higher proportion of HER2‐overexpressing cases experienced recurrence, but the difference was not significant. HER2‐amplification/overexpression is identifiable by immunohistochemistry, occurring infrequently in stage II–III CRC, rising in stage IV and further in KRAS/BRAFWT tumours. The value of HER2‐targeted therapy in patients with HER2‐amplified CRC must be tested in a clinical trial. © 2015 The Authors. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Pre-trial inter-laboratory analytical validation of the FOCUS4 personalised therapy trial

INTRODUCTION

Molecular characterisation of tumours is increasing personalisation of cancer therapy, tailored to an individual and their cancer. FOCUS4 is a molecularly stratified clinical trial for patients with advanced colorectal cancer. During an initial 16-week period of standard first-line chemotherapy, tumour tissue will undergo several molecular assays, with the results used for cohort allocation, then randomisation. Laboratories in Leeds and Cardiff will perform the molecular testing. The results of a rigorous pre-trial inter-laboratory analytical validation are presented and discussed.

METHODS

Wales Cancer Bank supplied FFPE tumour blocks from 97 mCRC patients with consent for use in further research. Both laboratories processed each sample according to an agreed definitive FOCUS4 laboratory protocol, reporting results directly to the MRC Trial Management Group for independent cross-referencing.

RESULTS

Pyrosequencing analysis of mutation status at KRAS codons12/13/61/146, NRAS codons12/13/61, BRAF codon600 and PIK3CA codons542/545/546/1047, generated highly concordant results. Two samples gave discrepant results; in one a PIK3CA mutation was detected only in Leeds, and in the other, a PIK3CA mutation was only detected in Cardiff. pTEN and mismatch repair (MMR) protein expression was assessed by immunohistochemistry (IHC) resulting in 6/97 discordant results for pTEN and 5/388 for MMR, resolved upon joint review. Tumour heterogeneity was likely responsible for pyrosequencing discrepancies. The presence of signet-ring cells, necrosis, mucin, edge-effects and over-counterstaining influenced IHC discrepancies.

CONCLUSIONS

Pre-trial assay analytical validation is essential to ensure appropriate selection of patients for targeted therapies. This is feasible for both mutation testing and immunohistochemical assays and must be built into the workup of such trials.

TRIAL REGISTRATION NUMBER

ISRCTN90061564.

KRAS and BRAF mutations in Nigerian colorectal cancers

PURPOSE

Activation of the KRAS oncogene is implicated in colorectal carcinogenesis and mutations have been reported in 30-50% of cases. BRAF mutation, though less common, is also reported and importantly associated with shorter progression-free interval. This study aims to determine the KRAS and BRAF mutation statuses of Nigerian colorectal cancers (CRC).

METHODS

Mutation analysis was carried out on archival paraffin-embedded blocks of CRC tissues. KRAS codons 12, 13 and 61 and BRAF V600E were assessed by pyrosequencing after DNA extraction from 200 cases at the Leeds Institute of Molecular Medicine, St. James's University Hospital, UK. Mutation rates and the spectra were determined.

RESULTS

Pyrosequencing was successful in 112 of 200 cases. KRAS mutation in codons 12 and 13 was demonstrated in 23 of 112 cases (21%); none in codon 61. BRAF mutation in codon 600 was demonstrated in 4.5%.

CONCLUSION

This study shows that 21% of Nigerian CRC patients carry a KRAS mutation; half the rate in Caucasians; and that BRAF mutation also occurs in Nigerian CRC cancers.

Intra-tumoral heterogeneity of KRAS and BRAF mutation status in patients with advanced colorectal cancer (aCRC) and cost-effectiveness of multiple sample testing

KRAS mutation status is established as a predictive biomarker of benefit from anti-EGFr therapies. Mutations are normally assessed using DNA extracted from one formalin-fixed, paraffin-embedded (FFPE) tumor block. We assessed heterogeneity of KRAS and BRAF mutation status intra-tumorally (multiple blocks from the same primary tumor). We also investigated the utility and efficiency of genotyping a ‘DNA cocktail’ prepared from multiple blocks. We studied 68 consenting patients in two randomized clinical trials. DNA was extracted, from ≥2 primary tumor FFPE blocks per patient. DNA was genotyped by pyrosequencing for KRAS codons 12, 13 and 61 and BRAF codon 600. In patients with heterogeneous mutation status, DNA cocktails were prepared and genotyped. Among 69 primary tumors in 68 patients, 7 (10.1%) showed intratumoral heterogeneity; 5 (7.2%) at KRAS codons 12, 13 and 2 (2.9%) at BRAF codon 600. In patients displaying heterogeneity, the relevant KRAS or BRAF mutation was also identified in ‘DNA cocktail’ samples when including DNA from mutant and wild-type blocks. Heterogeneity is uncommon but not insignificant. Testing DNA from a single block will wrongly assign wild-type status to 10% patients. Testing more than one block, or preferably preparation of a ‘DNA cocktail’ from two or more tumor blocks, improves mutation detection at minimal extra cost.

Postdural puncture headache after spinal anaesthesia in young orthopaedic outpatients using 27-g needles

PURPOSE

Two large studies reported a very low rate (0.5-1.8%) of postdural puncture headache (PDPH) with the use of 27-G spinal needles. We suspected that it might be higher in young ambulatory patients. The purpose of this study was to establish the rate prospectively in such a patient population using two types of needles.

METHODS

Two hundred male and female, outpatients, 18-45 yr, undergoing knee arthroscopy under spinal anaesthesia were randomly assigned to receive spinal anaesthesia with hyperbaric lidocaine 5% using either a Quincke or a Whitacre 27-G needle. Twenty patients choosing general anaesthesia formed a comparative group. Using a previously validated questionnaire, the incidence and nature of PDPH were evaluated by telephone three to five days after surgery by an anaesthetist unaware of the anaesthetic technique used. Once all data were collected, an anaesthetist not involved in the study determined in a blinded fashion which headaches were likely to be PDPH. Grading and classification of headaches were based on several criteria: postural nature, duration, intensity and confinement to bed.

RESULTS

The overall incidence of PDPH in both spinal groups was 9.3%. The incidence in women, 20.4%, was higher than in men, 5.5%, (P < 0.05). Only one patient required a blood patch. Both types of needle were comparable with respect to the incidence, severity and duration of PDPH, number of dural punctures and failed spinal blocks.

CONCLUSION

The rate of PDPH was higher than in large published studies with 27-G Quincke and Whitacre needles and greater in women than in men.

Referencing lung volume for measurements of respiratory system compliance in infants

We propose a method for measurements of respiratory system compliance (Crs) in spontaneously breathing infants, which circumvents the potential problems introduced by the breath-by-breath oscillations in the end-expiratory level, i.e., functional respiratory capacity (FRC). Changes in lung volume (V) and pressure at the airway opening (P(ao)) were measured in 10 infants breathing through a face mask. A first brief occlusion was to establish a reference V and the corresponding static P(ao); a second occlusion was done at a different V, within the same expiration, or in the following breath. Both occlusions were sufficiently long for the establishment of a stable P(ao) value. From the V difference (delta V, where delta V was at least 20% tidal volume) and the corresponding difference in P(ao) (delta P(ao)) Crs was computed and averaged (Crs[REF.VOL.] = delta V/delta P(ao). Although, on average, the results were similar to those obtained by the traditional multiple occlusions technique with linear regression analysis of the P(ao)-V data points (Crs[MOT]), in several infants Crs[REF.VOL.] tended to be slightly higher than Crs[MOT]. Some possibilities for this discrepancy are discussed. It seems likely that breath-to-breath oscillation in FRC may potentially lower Crs[MOT] by introducing a bias on the V measurement at low P(ao). We conclude that referencing V for Crs measurements in spontaneously breathing infants is a simple approach, which does not require linear regression analysis and circumvents the effects of oscillation in FRC.

Bereavement reactions of female Scots and Swazis: a preliminary comparison

Forty matched Scottish and Swazi girls and women reported the intensity of the bereavement reactions which they had experienced two weeks and one year after the death of a close relative. The Swazi respondents reported more intense grief reactions during the first two weeks of bereavement than the Scottish participants, but the only way in which the two nationalities differed one year after the death was that the Scottish participants had a greater tendency to report feelings of guilt than the Swazi respondents. It is suggested that ritualistic crying and saying farewell to a dying relative may intensify feelings of grief during the early days of bereavement but, in the context of a clearly defined period of mourning, may play a part in reducing later feelings of guilt. Nationality was not a good predictor of the overall bereavement reaction at either of the time periods. A better prediction was obtained from the number of exchanges with other people which were perceived as being unhelpful, and the number of interactions which were absent but longed for.

Causes of schizophrenia

The causes of schizophrenia are discussed in a speculative review in which the disease is considered as a whole body one which is not confined in its pathology or symptomatology to the brain. Both the genetic background and the possible effect of dietary factors are reviewed.