- Email: [email protected]
2156 Detection of early colorectal dysplasia using fluorescently-labeled lectins
Abstracts
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in 9 (16.1%) in BM specimens, no NRAS mutations were detected (details in Table 1). In 41 matched cases, the molecular profile concordance rate was 95.1%, with only 2 discordant cases. Median brain PFS (defined as the time interval from the date of stage IV to neurosurgery) was 9 months (95% CI 1.8–16.2), median survival after neurosurgery was 5.5 months (95% CI 4.7−6.3); median overall survival was 24.0 months (95% CI 15.6– 32.4). Patients with brain PFS longer than the median had a significantly better survival (p = 0.002). Conclusions: We report a high frequency of KRAS mutations in patients resected for BM from CRC and a very high concordance rate between the molecular profile of BM and that of matched primary tumors. No significant correlation between mutational status of BM and outcome was found. Table 1. Molecular profile of 56 BM from CRC underwent to neurosurgery
KRAS Wt Any mutation Codon 12 Codon 13 Codon 61 Codon 117 Codon 146 BRAF Wt Exon 15 (V600E) Exon 15 (D594G) PIK3CA Wt Any mutation Exon 9 Exon 20 Missing
Number of patients
%
20 36 24 8 0 2 2
35.7 64.3 42.9 14.3 0.0 3.6 3.6
50 5 1
89.2 8.9 1.8
37 9 7 2 1
66.1 16.1 12.5 3.6 1.8
No conflict of interest. 2154 POSTER Metastatic colorectal cancer has heterogeneous immune microenvironment and mutational expression M. Van den Eynde1 , B. Mlecnik2 , G. Bindea2 , T. Fredriksen2 , L. Lafontaine2 , N. Haicheur3 , F. Marliot3 , D. Debetancourt1 , A. Jouret-Mourin1 , C. Sempoux1 , J.F. Gigot1 , C. Hubert1 , A. Kartheuser1 , C. Remue1 , D. Leonard1 , J. Carrasco4 , Y. Humblet1 , F. Pages ` 3, J.P. Machiels1 , J. Galon2 . 1 Cliniques universitaires Saint-Luc, Institut Roi Albert II, Brussels, Belgium; 2 Centre de Recheche des Cordeliers, ´ ˆ INSERM, equipe 15, Paris, France; 3 Hopital Europeen Georges ˆ Pompidou, Immunology, Paris, France; 4 Grand Hopital de Charleroi, Medical Oncology, Charleroi, Belgium Background: Understanding the colorectal cancer (CRC) metastasis process is a major clinical challenge for treatment efficacy. CRC cells must successfully negotiate a series of complex steps for progression and establishment in a foreign tissue environment. We plan to analyze the immune microenvironment within all resected metastases (Ms) and corresponding primary tumor (PT) to investigate the possible tumor immune heterogeneity and the consequence for personalized-medicine approaches. Material and Methods: We performed a full whole-slide quantification of immune cell densities (CD3/CD8/CD45RO/CD20/FoxP3) in the core (CT) and invasive margin (IM) on all resected synchronous (Sync) and metachronous (Metac) Ms (n = 338) and available corresponding PT (n = 69) from a cohort of 114 operated metastatic CRC patients (pts). The mean density value was calculated for each marker in each tumor region (CT/IM) with a dedicated image analysis software on whole-slide images. Additionally, a somatic mutation profiling (Ion Torrent PGM technology) of 50 onco- and tumor suppressor genes from Ms (Sync and Metac) and PTs was performed on a subgroup of 12 pts with the highest tumor immune heterogeneity. Comparisons were made using the t-test and WilcoxonMann–Whitney test. Results: The global immune infiltration was mostly heterogeneous in each tumor region (CT/IM) within and across Ms (Sync/Metac) and PTs from all pts. CD3, CD8 and CD45RO densities were significantly higher in the Ms (CT/IM, Sync/Metac) compared to the PTs (p < 0.05). Conversely, higher CD20 and FOXP3 densities were observed in PTs (CT; p < 0.05). For pts with multiple Ms, the global T-cell infiltration was increased in small-sized Ms (CT/IM; p < 0.05). The analysis of the highest infiltrated metastasis per patient, showed that pts with a large number of Ms had a significantly
higher number of infiltrating immune cells compared to pts with few Ms (p < 0.05). Focusing on the group of pts with the highest tumor immune heterogeneity, a diverse mutational expression (TP53, PIK3CA, KDR, KIT, APC and KRAS) was observed between Sync and Metac Ms and PTs. Conclusions: A global heterogeneity of the tumor immune environment and mutational expression was observed in metastatic CRC, suggesting a genetic evolution of tumor clones during progression. It could pose major challenge to personalized-medicine and makes tumor-biopsy challenging for biomarker discovery. No conflict of interest. 2155 POSTER Fish oil increases the chemotherapeutic efficacy of 5-Fluorouracil by altering the membrane characteristics and drug uptake N. Agnihotri1 , I. Rani1 . 1 Panjab University, Biochemistry, Chandigarh, India. Background: 5-Fluorouracil (5-FU) is used for the treatment of colorectal cancer but has low therapeutic response rate and severe side effects. Recently fish oil (FO) rich in n-3 PUFAs (Polyunsaturated fatty acids) has been reported to chemosensitize tumor cells to anticancer drugs. The current study is designed to understand the mechanism of action of FO on chemotherapeutic efficacy of 5-FU in experimental colon carcinogenesis. Materials and Methods: Male Balb/c mice were divided into control and N,N -dimethylhydrazine dihydrochloride/dextran sodium sulphate (DMH/DSS) group. DMH/DSS treated animals were kept for 20wks for the development of colon cancer and further subdivided based upon the treatment with 5-FU and/or FO. The therapeutic efficacy of 5-FU alongwith FO was analyzed through assessment of survival rate, tumor volume and burden. Cytokeratin (CK19) expression and percentage of cancer stem cells was also estimated as prognostic markers. The mechanism of action of FO as an adjuvant was determined by estimating the levels of n-3 PUFAs i.e. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) in membrane and its effect on membrane characteristics and drug uptake in different organs. Results: In the current study, FO in combination with 5-FU led to a significant increase in survival rate and decrease in tumor volume and count in contrast to other groups. Synergism of 5-FU and FO was also reflected in significant inhibition in tumor growth as demonstrated by a decrease in CK19 expression and percentage of cancer stem cells. The supplementation of FO alongwith 5-FU increased the distribution of drug and its metabolite in the colon tissue and sparing the rest of organs. Nutritional intervention by FO with 5-FU also increased EPA and DHA content in the colon tissue and led to an increase in membrane fluidity and decrease in microviscosity. The effect of FO related to these alterations may be attributed to incorporation of n-3 PUFAs into cellular membrane lipids that alters membrane fluidity as well as membrane-related functions. This would not only facilitate the cellular uptake of cytotoxic drug specifically to the target tumor site but may reverse drug resistance. Conclusion: This preclinical study has demonstrated that the supplementation of FO may prove as a powerful adjuvant for the chemosensitization of colon cancer cells. No conflict of interest. 2156 POSTER Detection of early colorectal dysplasia using fluorescently-labeled lectins J. Kuo1 , A. Ibrahim2 , A. Neves1 , K. Brindle1 . 1 Cambridge University, Cancer Research UK Cambridge Institute, Cambridge, United Kingdom; 2 Cambridge University, Department of Pathology, Addenbrooke’s Hospital, Cambridge, United Kingdom Background: Screening for colorectal cancer (CRC) is currently performed using bright-field colonoscopy, which has low specificity and sensitivity for the detection of early dysplasia in the colon. Fluorescently labeled lectins have been applied topically for detecting glycosylation changes in early dysplastic lesions in the esophagus, providing a route for improved endoscopic detection using fluorescence endoscopy. We have identified here fluorescently labeled lectins that can detect changes in glycosylated biomarkers on the surface epithelium of early dysplasia in CRC. These probes may enable fluorescence-guided resection of dysplastic lesions at colonoscopy. Materials and Methods: Ninety-nine colon lesions in 48 patients (34 males, 14 females; mean patient age 68.8±8.3 yr, range 53−95 yr) were identified during routine colonoscopy at Addenbrooke’s Hospital, Cambridge, UK. Lesions suspected of being dysplastic or neoplastic, were detected using magnification colonoscopy or surgery, and removal performed at biopsy (11.7%) and/or polypectomy (62.1%), or partial colon
S386 resection (11.7%). Colon histological sections were stained with fluorescently labeled lectins, and the lectin binding to surface epithelium, which would be observable in colonoscopy, was compared with conventional histopathology for the presence of disease and disease stage. Results: Normal colonic epithelium (NE) occupied 40.1% of the area of all sections, hyperplastic polyps (HP) occupied 10.2%, low-grade (LGD) dysplasia 25.6%, high-grade (HGD) dysplasia 13.9%, and adenocarcinoma (C) 10.2%, as assessed by conventional histopathology based on H&E staining. Lesions were located in the ascending (10.4%), transverse (15.6%), descending (14.3%), sigmoid (42.9%) colon and rectum (7.8%), with the mean lesion size being 16.0±14.2 mm (range 2−60 mm). The lectin wheat germ agglutinin (WGA), when fluorescently-labeled, was capable of distinguishing epithelial regions containing NE or HP from regions containing LGD, HGD or cancer, with 81% sensitivity and 87% specificity. Conclusions: Automated analysis of fluorescently-labeled WGA binding to the surface epithelium of excised colon sections may be used for improving the assessment of early dysplasia in CRC. The same fluorescent lectin may also be useful as a topical imaging agent for improving detection of early dysplasia using fluorescence colonoscopy, increasing the early diagnosis of CRC and improving patient survival. No conflict of interest. 2157 POSTER Comparison of KRAS and PIK3CA gene status between primary tumours and paired metastases in metastatic or recurrent colorectal cancer J.E. Ying1 , Q. He1 , W.Y. Sun2 , Q. Xu1 , D.C. Li3 , B.X. Liu1 , Y.A. Du4 , W.M. Cao1 , L.Y. Chen1 , W. Wu2 , L. Chen1 , C. Luo1 . 1 Zhejiang Cancer Hospital, Abdominal Medical Oncology, Zhejiang, China; 2 Zhejiang Cancer Hospital, Pathology, Zhejiang, China; 3 Zhejiang Cancer Hospital, Colorectal Surgical Oncology, Zhejiang, China; 4 Zhejiang Cancer Hospital, Abdominal Surgical Oncology, Zhejiang, China Background: In metastatic or recurrent colorectal cancer (MRCRC), the concordance of KRAS and PIK3CA mutation status between the primary tumors and metastases is still controversial. The purpose of this study was to evaluate the association between KRAS and PIK3CA mutational status and various clinicopathologic features, and compare their genotype of primary tumors with that of the paired metastatic tumors. Methods: We compared the mutation status of KRAS and PIK3CA between the primary tumors and the paired metastases of 59 MRCRC patients with available tissues (resection or biopsy). The presence of KRAS and PIK3CA mutations were determined on both primary tumors and paired metastatic samples by direct sequencing analysis. Results: 17 patients (28.8%) had the KRAS mutation and 46 patients (80.0%) had the PI3KCA mutation in any place of the primary or metastatic tumors. The KRAS mutation was observed in 10 primary tumors and 11 related metastasis (16.9%vs. 18.6%), while PIK3CA mutation was found in 26 primary tumors and 32 related metastasis (44.1% vs. 54.2%). KRAS status was concordant between primary and metastatic sites in 45 patients (76.3%, kappa = 0.157), and the concordance of PIK3CA status was found in 25 patients (42.4%, kappa = −0.141). The PIK3CA status discordance rate was significantly higher in 40 patients undergoing metachronous resection of primary tumor or metastasis [67.5% (27/40)], compared to that in 19 patients with synchronous resection of primary tumor or metastasis [36.8% (7/19); p = 0.026].Conclusions: Our results demonstrate that low concordance of KRAS and high disconcordance of PIK3CA mutational status exist between the primary tumors and paired metastasis, and these findings remind us to have second thoughts about the need to evaluate metastatic tumors separately rather than only based on the primary tumor data when targeted therapy is considered. No conflict of interest.
Abstracts 2158 POSTER The Nationwide Cancer Genome Screening Project for Gastrointestinal Cancer in Japan (GI-SCREEN): Simultaneous identification of KRAS, NRAS, BRAF, and PIK3CA mutation in advanced colorectal cancer (aCRC) (GI-SCREEN 2013−01) T. Denda1 , K. Shitara2 , S. Fuji3 , T. Kajiwara4 , S. Yuki5 , T. Eguchi Nakajima6 , A. Takashima7 , K. Kawasaki8 , T. Tamura9 , T. Esaki10 , N. Daisuke11 , H. Ebi12 , K. Toshihiro13 , H. Taniguchi14 , K. Akagi15 , T. Yamanaka16 , A. Ochiai17 , D. Toshihiko18 , A. Ohtsu19 , T. Yoshino18 . 1 Chiba Cancer Center, Gastroenterology, Chiba, Japan; 2 National Cancer Center Hospital East, Gastrointestinal Oncolog, Kashiwa, Japan; 3 National Cancer Center Hospital East, Pathology, Kashiwa, Japan; 4 Shikoku Cancer Center, Gastrointestinal Medical Oncology, Ehime, Japan; 5 Hokkaido University Hospital, Gastroenterology, Sapporo, Japan; 6 St. Marianna University School of Medicine, Medical Oncology, Kawasaki, Japan; 7 National Cancer Center Hospital, Gastrointestinal Medical Oncology, Tokyo, Japan; 8 Keio University School of Medicine, Gastroenterology, Yokohama, Japan; 9 Kinki University, Medical Oncology, Osaka, Japan; 10 National Hospital Organization Kyushu Cancer Center, Department of Gastrointestinal and Medical Oncology, Fukuoka, Japan; 11 Kyorin University Hospital, Medical Oncology, Mitaka-shi, Japan; 12 Kanazawa University, Medical Oncology, Kanazawa, Japan; 13 Osaka University Graduate School of Medicine, Medical Oncology, Suita, Japan; 14 Aichi Cancer Center Hospital, Department of Clinical Oncology, Nagoya, Japan; 15 Saitama Cancer Center, Division of Molecular Diagnosis and Cancer Prevention, Saitama, Japan; 16 Yokohama City University, Department of Biostatistics, Yokohama, Japan; 17 National Cancer Center Hospital, Pathology Division, Tokyo, Japan; 18 National Cancer Center Hospital East, Gastrointestinal Oncology, Kashiwa, Japan; 19 National Cancer Center, Exploratory Oncology Research & Clinical Trial Center, Kashiwa, Japan Background: Recent studies confirmed that minor RAS mutations are associated with the resistance to anti-EGFR therapy for aCRC. Although the impact of BRAF or PIK3CA mutation on efficacy of anti-EGFR therapy is still controversial, targeting agents for these mutations or related pathway are under development. Efficient screening systems for these relatively minor mutations with short turnaround time are necessary for the successful development of targeted therapies. Material and Methods: This study was initiated in February 2014 as one of new nationwide cancer genomic screening projects for advanced gastrointestinal cancer patients in Japan. The objective of this study is to evaluate the frequency of oncogenic mutations in CRCs and to identify patients who are candidate for clinical trial of targeting agents. Patients with aCRC who are planned to receive systemic chemotherapy were eligible. A total of 36 mutations of KRAS codon 61, 146, NRAS codon 12, 13, 61, BRAF codon 600, PIK3CA codon 542,545,546 and 1047 in genomic DNA of cancer cells were simultaneously analyzed at a quality-controlled central laboratory using Luminex (xMAP) technology in a single reaction using 50 ng of DNA. Results: As of April in 2015, this study is ongoing with the participation of 18 cancer centers. A total of 853 aCRC patients were enrolled until Jan. 31st 2015 to this study and 832 tumor samples has been analyzed with success rate for genomic analysis of 100%. Mutations in KRAS exon 2, other KRAS or NRAS, BRAF and PIK3CA were detected in 33.9%, 8.2%, 4.6%, and 8.5%, respectively. A total of 11.5% of patients without KRAS exon 2 mutations had other RAS mutations. Among the 38 patients with BRAF mutation, 5 patients was enrolled in early clinical trials of BRAF targeting therapy and most of other patients are still treated with standard chemotherapies, which may become future candidates for clinical trials. Conclusions: From our preliminary results, this nationwide screening system enabled to detect rare mutations using limited amounts of samples from aCRC. This may facilitate the enrollment of patients in IND registration trials for targeted therapies as well as optimal individualized treatment. The method for genome analysis was changed to next generation sequencing using the Oncomine Cancer Research Panel (OCP) in Feb. 2015 with ongoing enrollment. Further updated results will be presented. No conflict of interest. 2159 POSTER Expression of mucin carbohydrate antigens (tn and sialyl-tn) as potential prognostic biomarkers in human colorectal carcinoma A. Guangyu1 , X. Feng1 , X. Lingling1 , Y. Jiannan1 , L. Fuquan1 . 1 Beijing Chao-yang Hospital, Oncology, Beijing, China Background: Altered glycosylation of mucins leading to the expression of Tn and sialyl-Tn antigens has been shown in colorectal carcinoma, but its relationship with prognosis is still controversial.
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in 9 (16.1%) in BM specimens, no NRAS mutations were detected (details in Table 1). In 41 matched cases, the molecular profile concordance rate was 95.1%, with only 2 discordant cases. Median brain PFS (defined as the time interval from the date of stage IV to neurosurgery) was 9 months (95% CI 1.8–16.2), median survival after neurosurgery was 5.5 months (95% CI 4.7−6.3); median overall survival was 24.0 months (95% CI 15.6– 32.4). Patients with brain PFS longer than the median had a significantly better survival (p = 0.002). Conclusions: We report a high frequency of KRAS mutations in patients resected for BM from CRC and a very high concordance rate between the molecular profile of BM and that of matched primary tumors. No significant correlation between mutational status of BM and outcome was found. Table 1. Molecular profile of 56 BM from CRC underwent to neurosurgery
KRAS Wt Any mutation Codon 12 Codon 13 Codon 61 Codon 117 Codon 146 BRAF Wt Exon 15 (V600E) Exon 15 (D594G) PIK3CA Wt Any mutation Exon 9 Exon 20 Missing
Number of patients
%
20 36 24 8 0 2 2
35.7 64.3 42.9 14.3 0.0 3.6 3.6
50 5 1
89.2 8.9 1.8
37 9 7 2 1
66.1 16.1 12.5 3.6 1.8
No conflict of interest. 2154 POSTER Metastatic colorectal cancer has heterogeneous immune microenvironment and mutational expression M. Van den Eynde1 , B. Mlecnik2 , G. Bindea2 , T. Fredriksen2 , L. Lafontaine2 , N. Haicheur3 , F. Marliot3 , D. Debetancourt1 , A. Jouret-Mourin1 , C. Sempoux1 , J.F. Gigot1 , C. Hubert1 , A. Kartheuser1 , C. Remue1 , D. Leonard1 , J. Carrasco4 , Y. Humblet1 , F. Pages ` 3, J.P. Machiels1 , J. Galon2 . 1 Cliniques universitaires Saint-Luc, Institut Roi Albert II, Brussels, Belgium; 2 Centre de Recheche des Cordeliers, ´ ˆ INSERM, equipe 15, Paris, France; 3 Hopital Europeen Georges ˆ Pompidou, Immunology, Paris, France; 4 Grand Hopital de Charleroi, Medical Oncology, Charleroi, Belgium Background: Understanding the colorectal cancer (CRC) metastasis process is a major clinical challenge for treatment efficacy. CRC cells must successfully negotiate a series of complex steps for progression and establishment in a foreign tissue environment. We plan to analyze the immune microenvironment within all resected metastases (Ms) and corresponding primary tumor (PT) to investigate the possible tumor immune heterogeneity and the consequence for personalized-medicine approaches. Material and Methods: We performed a full whole-slide quantification of immune cell densities (CD3/CD8/CD45RO/CD20/FoxP3) in the core (CT) and invasive margin (IM) on all resected synchronous (Sync) and metachronous (Metac) Ms (n = 338) and available corresponding PT (n = 69) from a cohort of 114 operated metastatic CRC patients (pts). The mean density value was calculated for each marker in each tumor region (CT/IM) with a dedicated image analysis software on whole-slide images. Additionally, a somatic mutation profiling (Ion Torrent PGM technology) of 50 onco- and tumor suppressor genes from Ms (Sync and Metac) and PTs was performed on a subgroup of 12 pts with the highest tumor immune heterogeneity. Comparisons were made using the t-test and WilcoxonMann–Whitney test. Results: The global immune infiltration was mostly heterogeneous in each tumor region (CT/IM) within and across Ms (Sync/Metac) and PTs from all pts. CD3, CD8 and CD45RO densities were significantly higher in the Ms (CT/IM, Sync/Metac) compared to the PTs (p < 0.05). Conversely, higher CD20 and FOXP3 densities were observed in PTs (CT; p < 0.05). For pts with multiple Ms, the global T-cell infiltration was increased in small-sized Ms (CT/IM; p < 0.05). The analysis of the highest infiltrated metastasis per patient, showed that pts with a large number of Ms had a significantly
higher number of infiltrating immune cells compared to pts with few Ms (p < 0.05). Focusing on the group of pts with the highest tumor immune heterogeneity, a diverse mutational expression (TP53, PIK3CA, KDR, KIT, APC and KRAS) was observed between Sync and Metac Ms and PTs. Conclusions: A global heterogeneity of the tumor immune environment and mutational expression was observed in metastatic CRC, suggesting a genetic evolution of tumor clones during progression. It could pose major challenge to personalized-medicine and makes tumor-biopsy challenging for biomarker discovery. No conflict of interest. 2155 POSTER Fish oil increases the chemotherapeutic efficacy of 5-Fluorouracil by altering the membrane characteristics and drug uptake N. Agnihotri1 , I. Rani1 . 1 Panjab University, Biochemistry, Chandigarh, India. Background: 5-Fluorouracil (5-FU) is used for the treatment of colorectal cancer but has low therapeutic response rate and severe side effects. Recently fish oil (FO) rich in n-3 PUFAs (Polyunsaturated fatty acids) has been reported to chemosensitize tumor cells to anticancer drugs. The current study is designed to understand the mechanism of action of FO on chemotherapeutic efficacy of 5-FU in experimental colon carcinogenesis. Materials and Methods: Male Balb/c mice were divided into control and N,N -dimethylhydrazine dihydrochloride/dextran sodium sulphate (DMH/DSS) group. DMH/DSS treated animals were kept for 20wks for the development of colon cancer and further subdivided based upon the treatment with 5-FU and/or FO. The therapeutic efficacy of 5-FU alongwith FO was analyzed through assessment of survival rate, tumor volume and burden. Cytokeratin (CK19) expression and percentage of cancer stem cells was also estimated as prognostic markers. The mechanism of action of FO as an adjuvant was determined by estimating the levels of n-3 PUFAs i.e. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) in membrane and its effect on membrane characteristics and drug uptake in different organs. Results: In the current study, FO in combination with 5-FU led to a significant increase in survival rate and decrease in tumor volume and count in contrast to other groups. Synergism of 5-FU and FO was also reflected in significant inhibition in tumor growth as demonstrated by a decrease in CK19 expression and percentage of cancer stem cells. The supplementation of FO alongwith 5-FU increased the distribution of drug and its metabolite in the colon tissue and sparing the rest of organs. Nutritional intervention by FO with 5-FU also increased EPA and DHA content in the colon tissue and led to an increase in membrane fluidity and decrease in microviscosity. The effect of FO related to these alterations may be attributed to incorporation of n-3 PUFAs into cellular membrane lipids that alters membrane fluidity as well as membrane-related functions. This would not only facilitate the cellular uptake of cytotoxic drug specifically to the target tumor site but may reverse drug resistance. Conclusion: This preclinical study has demonstrated that the supplementation of FO may prove as a powerful adjuvant for the chemosensitization of colon cancer cells. No conflict of interest. 2156 POSTER Detection of early colorectal dysplasia using fluorescently-labeled lectins J. Kuo1 , A. Ibrahim2 , A. Neves1 , K. Brindle1 . 1 Cambridge University, Cancer Research UK Cambridge Institute, Cambridge, United Kingdom; 2 Cambridge University, Department of Pathology, Addenbrooke’s Hospital, Cambridge, United Kingdom Background: Screening for colorectal cancer (CRC) is currently performed using bright-field colonoscopy, which has low specificity and sensitivity for the detection of early dysplasia in the colon. Fluorescently labeled lectins have been applied topically for detecting glycosylation changes in early dysplastic lesions in the esophagus, providing a route for improved endoscopic detection using fluorescence endoscopy. We have identified here fluorescently labeled lectins that can detect changes in glycosylated biomarkers on the surface epithelium of early dysplasia in CRC. These probes may enable fluorescence-guided resection of dysplastic lesions at colonoscopy. Materials and Methods: Ninety-nine colon lesions in 48 patients (34 males, 14 females; mean patient age 68.8±8.3 yr, range 53−95 yr) were identified during routine colonoscopy at Addenbrooke’s Hospital, Cambridge, UK. Lesions suspected of being dysplastic or neoplastic, were detected using magnification colonoscopy or surgery, and removal performed at biopsy (11.7%) and/or polypectomy (62.1%), or partial colon
S386 resection (11.7%). Colon histological sections were stained with fluorescently labeled lectins, and the lectin binding to surface epithelium, which would be observable in colonoscopy, was compared with conventional histopathology for the presence of disease and disease stage. Results: Normal colonic epithelium (NE) occupied 40.1% of the area of all sections, hyperplastic polyps (HP) occupied 10.2%, low-grade (LGD) dysplasia 25.6%, high-grade (HGD) dysplasia 13.9%, and adenocarcinoma (C) 10.2%, as assessed by conventional histopathology based on H&E staining. Lesions were located in the ascending (10.4%), transverse (15.6%), descending (14.3%), sigmoid (42.9%) colon and rectum (7.8%), with the mean lesion size being 16.0±14.2 mm (range 2−60 mm). The lectin wheat germ agglutinin (WGA), when fluorescently-labeled, was capable of distinguishing epithelial regions containing NE or HP from regions containing LGD, HGD or cancer, with 81% sensitivity and 87% specificity. Conclusions: Automated analysis of fluorescently-labeled WGA binding to the surface epithelium of excised colon sections may be used for improving the assessment of early dysplasia in CRC. The same fluorescent lectin may also be useful as a topical imaging agent for improving detection of early dysplasia using fluorescence colonoscopy, increasing the early diagnosis of CRC and improving patient survival. No conflict of interest. 2157 POSTER Comparison of KRAS and PIK3CA gene status between primary tumours and paired metastases in metastatic or recurrent colorectal cancer J.E. Ying1 , Q. He1 , W.Y. Sun2 , Q. Xu1 , D.C. Li3 , B.X. Liu1 , Y.A. Du4 , W.M. Cao1 , L.Y. Chen1 , W. Wu2 , L. Chen1 , C. Luo1 . 1 Zhejiang Cancer Hospital, Abdominal Medical Oncology, Zhejiang, China; 2 Zhejiang Cancer Hospital, Pathology, Zhejiang, China; 3 Zhejiang Cancer Hospital, Colorectal Surgical Oncology, Zhejiang, China; 4 Zhejiang Cancer Hospital, Abdominal Surgical Oncology, Zhejiang, China Background: In metastatic or recurrent colorectal cancer (MRCRC), the concordance of KRAS and PIK3CA mutation status between the primary tumors and metastases is still controversial. The purpose of this study was to evaluate the association between KRAS and PIK3CA mutational status and various clinicopathologic features, and compare their genotype of primary tumors with that of the paired metastatic tumors. Methods: We compared the mutation status of KRAS and PIK3CA between the primary tumors and the paired metastases of 59 MRCRC patients with available tissues (resection or biopsy). The presence of KRAS and PIK3CA mutations were determined on both primary tumors and paired metastatic samples by direct sequencing analysis. Results: 17 patients (28.8%) had the KRAS mutation and 46 patients (80.0%) had the PI3KCA mutation in any place of the primary or metastatic tumors. The KRAS mutation was observed in 10 primary tumors and 11 related metastasis (16.9%vs. 18.6%), while PIK3CA mutation was found in 26 primary tumors and 32 related metastasis (44.1% vs. 54.2%). KRAS status was concordant between primary and metastatic sites in 45 patients (76.3%, kappa = 0.157), and the concordance of PIK3CA status was found in 25 patients (42.4%, kappa = −0.141). The PIK3CA status discordance rate was significantly higher in 40 patients undergoing metachronous resection of primary tumor or metastasis [67.5% (27/40)], compared to that in 19 patients with synchronous resection of primary tumor or metastasis [36.8% (7/19); p = 0.026].Conclusions: Our results demonstrate that low concordance of KRAS and high disconcordance of PIK3CA mutational status exist between the primary tumors and paired metastasis, and these findings remind us to have second thoughts about the need to evaluate metastatic tumors separately rather than only based on the primary tumor data when targeted therapy is considered. No conflict of interest.
Abstracts 2158 POSTER The Nationwide Cancer Genome Screening Project for Gastrointestinal Cancer in Japan (GI-SCREEN): Simultaneous identification of KRAS, NRAS, BRAF, and PIK3CA mutation in advanced colorectal cancer (aCRC) (GI-SCREEN 2013−01) T. Denda1 , K. Shitara2 , S. Fuji3 , T. Kajiwara4 , S. Yuki5 , T. Eguchi Nakajima6 , A. Takashima7 , K. Kawasaki8 , T. Tamura9 , T. Esaki10 , N. Daisuke11 , H. Ebi12 , K. Toshihiro13 , H. Taniguchi14 , K. Akagi15 , T. Yamanaka16 , A. Ochiai17 , D. Toshihiko18 , A. Ohtsu19 , T. Yoshino18 . 1 Chiba Cancer Center, Gastroenterology, Chiba, Japan; 2 National Cancer Center Hospital East, Gastrointestinal Oncolog, Kashiwa, Japan; 3 National Cancer Center Hospital East, Pathology, Kashiwa, Japan; 4 Shikoku Cancer Center, Gastrointestinal Medical Oncology, Ehime, Japan; 5 Hokkaido University Hospital, Gastroenterology, Sapporo, Japan; 6 St. Marianna University School of Medicine, Medical Oncology, Kawasaki, Japan; 7 National Cancer Center Hospital, Gastrointestinal Medical Oncology, Tokyo, Japan; 8 Keio University School of Medicine, Gastroenterology, Yokohama, Japan; 9 Kinki University, Medical Oncology, Osaka, Japan; 10 National Hospital Organization Kyushu Cancer Center, Department of Gastrointestinal and Medical Oncology, Fukuoka, Japan; 11 Kyorin University Hospital, Medical Oncology, Mitaka-shi, Japan; 12 Kanazawa University, Medical Oncology, Kanazawa, Japan; 13 Osaka University Graduate School of Medicine, Medical Oncology, Suita, Japan; 14 Aichi Cancer Center Hospital, Department of Clinical Oncology, Nagoya, Japan; 15 Saitama Cancer Center, Division of Molecular Diagnosis and Cancer Prevention, Saitama, Japan; 16 Yokohama City University, Department of Biostatistics, Yokohama, Japan; 17 National Cancer Center Hospital, Pathology Division, Tokyo, Japan; 18 National Cancer Center Hospital East, Gastrointestinal Oncology, Kashiwa, Japan; 19 National Cancer Center, Exploratory Oncology Research & Clinical Trial Center, Kashiwa, Japan Background: Recent studies confirmed that minor RAS mutations are associated with the resistance to anti-EGFR therapy for aCRC. Although the impact of BRAF or PIK3CA mutation on efficacy of anti-EGFR therapy is still controversial, targeting agents for these mutations or related pathway are under development. Efficient screening systems for these relatively minor mutations with short turnaround time are necessary for the successful development of targeted therapies. Material and Methods: This study was initiated in February 2014 as one of new nationwide cancer genomic screening projects for advanced gastrointestinal cancer patients in Japan. The objective of this study is to evaluate the frequency of oncogenic mutations in CRCs and to identify patients who are candidate for clinical trial of targeting agents. Patients with aCRC who are planned to receive systemic chemotherapy were eligible. A total of 36 mutations of KRAS codon 61, 146, NRAS codon 12, 13, 61, BRAF codon 600, PIK3CA codon 542,545,546 and 1047 in genomic DNA of cancer cells were simultaneously analyzed at a quality-controlled central laboratory using Luminex (xMAP) technology in a single reaction using 50 ng of DNA. Results: As of April in 2015, this study is ongoing with the participation of 18 cancer centers. A total of 853 aCRC patients were enrolled until Jan. 31st 2015 to this study and 832 tumor samples has been analyzed with success rate for genomic analysis of 100%. Mutations in KRAS exon 2, other KRAS or NRAS, BRAF and PIK3CA were detected in 33.9%, 8.2%, 4.6%, and 8.5%, respectively. A total of 11.5% of patients without KRAS exon 2 mutations had other RAS mutations. Among the 38 patients with BRAF mutation, 5 patients was enrolled in early clinical trials of BRAF targeting therapy and most of other patients are still treated with standard chemotherapies, which may become future candidates for clinical trials. Conclusions: From our preliminary results, this nationwide screening system enabled to detect rare mutations using limited amounts of samples from aCRC. This may facilitate the enrollment of patients in IND registration trials for targeted therapies as well as optimal individualized treatment. The method for genome analysis was changed to next generation sequencing using the Oncomine Cancer Research Panel (OCP) in Feb. 2015 with ongoing enrollment. Further updated results will be presented. No conflict of interest. 2159 POSTER Expression of mucin carbohydrate antigens (tn and sialyl-tn) as potential prognostic biomarkers in human colorectal carcinoma A. Guangyu1 , X. Feng1 , X. Lingling1 , Y. Jiannan1 , L. Fuquan1 . 1 Beijing Chao-yang Hospital, Oncology, Beijing, China Background: Altered glycosylation of mucins leading to the expression of Tn and sialyl-Tn antigens has been shown in colorectal carcinoma, but its relationship with prognosis is still controversial.