Developing a Raman spectroscopy-based tool to stratify patient response to pre-operative radiotherapy in rectal cancer

Rectal cancer patients frequently receive pre-operative radiotherapy (RT), prior to surgical resection. However, colorectal cancer is heterogeneous and the degree of tumour response to pre-operative RT is highly variable. There are currently no clinically approved methods of predicting response to RT, and a significant proportion of patients will show no clinical benefit, despite enduring the side-effects. We evaluated the use of Raman spectroscopy (RS), a non-destructive technique able to provide the unique chemical fingerprint of tissues, as a potential tool to stratify patient response to pre-operative RT. Raman measurements were obtained from the formalin-fixed, paraffin-embedded (FFPE) pre-treatment biopsy specimens of 20 rectal cancer patients who received pre-operative RT. A principal component analysis and linear discriminant analysis algorithm was able to classify patient response to pre-operative RT as good or poor, with an accuracy of 86.04 ± 0.14% (standard error). Patients with a good response to RT showed greater contributions from protein-associated peaks, whereas patients who responded poorly showed greater lipid contributions. These results demonstrate that RS is able to reliably classify tumour response to pre-operative RT from FFPE biopsies and highlights its potential to guide personalised cancer patient treatment

5-Aminolevulinic acid-mediated fluorescence diagnosis of colon cancer: A histopathological comparison of fluorescent and non-fluorescent tumours

Background: 5-Aminolevulinic acid (5-ALA) selectively accumulates in cancer cells and is metabolised in the mitochondria to the fluorophore protoporphyrin IX. The GLiSten trial evaluated 5-ALA as a fluorescent probe for intraoperative detection of colon cancer and lymph node metastases. Only 13 of 40 cases showed fluorescence, suggesting a fundamental difference between fluorescent and non-fluorescent cancers. The aim of this study was to investigate whether differences in fluorescence were due to tumour cellularity, in particular T cell infiltration, which may be of prognostic significance. Method: Primary tumour tissue was available from 30 patients. The density of tumour cells, vascularity and stromal compartment size were quantified using digitally scanned tissue sections stained with haematoxylin and eosin. A set of 300 random points was superimposed onto each tumour image. The structure indicated by each point was then categorised as tumour, stroma, vessel or other. The proportions of tumour and vessel points gave the tumour cell density and vessel density respectively. The relative size of the stromal compartment was given by the tumour to stroma ratio. A tissue section was also stained for the T cell marker CD3 by immunohistochemistry. Percentage staining was quantified in three high-density fields using the Nuance imaging system. Results: We were unable to detect any difference between fluorescent and non-fluorescent cancers in terms of tumour cell density (difference in means 3.7%; P = 0.452), vessel density (difference in means 0.17%; P = 0.684), tumour-stroma ratio (difference in mean ratios 0.12; P = 0.934), or T cell count (difference in means 0.92%; P = 0.726). Furthermore, comparisons of the distributions of each variable demonstrated substantial overlap between the fluorescent and non-fluorescent cohorts. Conclusion: The results suggest that tumour and microenvironment structure do not differ between cancers that fluoresce with 5-ALA and those that do not. We therefore propose that the cellular metabolism of 5-ALA is a more likely explanation for differential fluorescence

Intra-tumoural stromal morphometry predicts disease recurrence but not response to 5-fluorouracil – results from the QUASAR trial of colorectal cancer

Introduction: The biological importance of tumour-associated stroma is increasingly apparent, yet clinical utility remains ill-defined. In stage-II / Dukes B colorectal cancer (CRC), clinical biomarkers are urgently required to direct therapeutic options. We report here prognostic/predictive analyses, and molecular associations, of stromal morphometric quantification in the Quick and Simple and Reliable (QUASAR) trial of CRC. Materials and methods: Relative proportions of tumour epithelium (PoT) or stroma (PoS) were morphometrically quantified using digitised haematoxylin and eosin sections derived from 1,800 patients enrolled in QUASAR which randomised 3,239 (91% stage II) CRC patients between adjuvant fluorouracil/folinic acid (FUFA) chemotherapy and observation. The prognostic/predictive value of PoT/PoS measures were determined by stratified log-rank analyses. Results: High tumour stroma (≥50%) was associated with increased recurrence risk: 31.3% (143/457) recurrence for ≥50% versus 21.9% (294/1,343) if <50% [Rate ratio (RR)=1.62; 95%CI 1.30-2.02, p<0.0001)]. For stromal proportions of ≥65%, 40% (46/115) of patients had recurrent disease within 10 years. The adverse prognostic effect of high stroma was independent of established prognostic variables, and maintained in stage II / Dukes B patients (RR=1.62; 95%CI=1.26-2.08; p=0.0002). KRAS mutation in the presence of high stroma augmented recurrence risk (RR=2.93; 95%CI=1.87-4.59; p=0.0005). Stromal morphometry did not predict response to FUFA chemotherapy. Discussion: Simple digital morphometry applied to a single representative H&E section identifies CRC patients with over 50% higher risk of disease recurrence. This technique can reliably partition patients into sub-populations with differential risks of tumour recurrence in a simple and cost-effective manner. Further prospective validation is warranted

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

545P Epidermal growth factor receptor (EGFR) copy number (CN) as a biomarker of prognosis and panitumumab (Pan) benefit in RAS-wt advanced colorectal cancer (aCRC)

Background: Whilst RAS mutations predict which aCRC patients (pts) will not benefit from anti-EGFR agents, RAS-wt status does not reliably predict who will. Several studies report that high EGFR ligand expression (EREG/AREG) is predictive of anti-EGFR agent benefit but progression towards clinical utility is limited by lack of consensus on a clinical dichotomisation point and additional tumor material required. Here we explore EGFR copy number as a biomarker of prognosis and predictor of Pan benefit in a randomised trial in aCRC. Methods: EGFR CN, EREG/AREG RNA expression, RAS/RAF mutations were assessed in tumor from 275 pts randomised to 2nd-line irinotecan (Ir) or IrPan (PICCOLO, Lancet Onc 14:749-59). EGFR CN status was measured by the Affymetrix OncoScan array, analysed using Biodiscovery Nexus software and defined as normal (2 copies) or gain (>2 copies). Prognostic analysis was in Ir alone pts. Predictive analysis, in the 234 RAS-wt pts, compared baseline values with outcomes using Cox proportional hazards models. Results: 196 (71.3%) pts were classified as EGFR gain and 79 (28.7%) as normal. EGFR gain was significantly associated with high EREG and AREG RNA expression (both p < 0.001). EGFR gain was not prognostic for OS (p = 0.97) or PFS (p = 0.98). However, it was predictive of Pan benefit: in RAS-wt pts with EGFR gain, median PFS was 5.7 mo (IrPan) vs 3.7 mo (Ir) (HR = 0.60[0.43-0.83], p = 0.002), but pts with normal EGFR had no benefit: 3.4 mo (IrPan) vs 2.9 mo (Ir) (HR = 1.23[0.72-2.08], p = 0.45); interaction p = 0.02. Significant PFS biomarker/treatment interaction was also seen in all 275 pts, including RAS or RAF mutants (p = 0.01). In RAS-wt pts EGFR gain was associated with higher response rates than normal with IrPan (45.3% vs 18.7%, p = 0.01) but not with Ir (13.3% vs 12.9%, p = 1.0). Interaction was not significant (p = 0.22) or for OS (p = 0.20). Conclusions: EGFR CN status may allow for further stratification for Pan benefit in RAS-wt patients. Normal EGFR CN status identified nearly 1/3 of pts without Pan benefit. This biomarker is consistent with EGFR ligand data, and is a DNA-based assay with a clearly definable dichotomised cut-point and therefore is of potential clinical utility

Intra-tumoural stromal morphometry predicts disease recurrence but not response to 5-fluorouracil - results from the QUASAR trial of colorectal cancer.

INTRODUCTION: The biological importance of tumour-associated stroma is increasingly apparent, yet clinical utility remains ill-defined. In stage-II / Dukes B colorectal cancer (CRC), clinical biomarkers are urgently required to direct therapeutic options. We report here prognostic/predictive analyses, and molecular associations, of stromal morphometric quantification in the Quick and Simple and Reliable (QUASAR) trial of CRC MATERIALS AND METHODS: Relative proportions of tumour epithelium (PoT) or stroma (PoS) were morphometrically quantified using digitised haematoxylin and eosin sections derived from 1,800 patients enrolled in QUASAR which randomised 3,239 (91% stage II) CRC patients between adjuvant fluorouracil/folinic acid (FUFA) chemotherapy and observation. The prognostic/predictive value of PoT/PoS measures were determined by stratified log-rank analyses RESULTS: High tumour stroma (≥50%) was associated with increased recurrence risk: 31.3% (143/457) recurrence for ≥50% versus 21.9% (294/1,343) if &lt;50% [Rate ratio (RR)=1.62; 95%CI 1.30-2.02, p&lt;0.0001)]. For stromal proportions of ≥65%, 40% (46/115) of patients had recurrent disease within 10 years. The adverse prognostic effect of high stroma was independent of established prognostic variables, and maintained in stage II / Dukes B patients (RR=1.62; 95%CI=1.26-2.08; p=0.0002). KRAS mutation in the presence of high stroma augmented recurrence risk (RR=2.93; 95%CI=1.87-4.59; p=0.0005). Stromal morphometry did not predict response to FUFA chemotherapy DISCUSSION: Simple digital morphometry applied to a single representative H&amp;E section identifies CRC patients with over 50% higher risk of disease recurrence. This technique can reliably partition patients into sub-populations with differential risks of tumour recurrence in a simple and cost-effective manner. Further prospective validation is warranted. This article is protected by copyright. All rights reserved.</p