Clinical significance of intratumoral HER2 heterogeneity on trastuzumab efficacy using endoscopic biopsy specimens in patients with advanced HER2 positive gastric cancer

BACKGROUND

We recently reported the clinical significance of intratumoral HER2 heterogeneity on trastuzumab efficacy using surgical specimens; patients with homogeneously HER2 positive gastric cancer benefitted more from trastuzumab. However, the majority of patients are diagnosed by endoscopic biopsy, and surgical specimens are not available in these patients. The aim of this study is to verify clinical significance of HER2 heterogeneity on trastuzumab efficacy using biopsy specimens.

METHODS

Eighty-seven patients, who received trastuzumab-based chemotherapy and whose endoscopic biopsy specimens were available for HER2 assessment, were consecutively enrolled. When all tumor cells in all biopsy specimens overexpressed HER2 protein, it was defined as homogeneously HER2 (homo-HER2) positive group, and the others were defined as heterogeneously HER2 (hetero-HER2) positive group. Progression-free survival (PFS), overall survival (OS) and objective response rate (ORR) were evaluated.

RESULTS

Thirty-four patients (39%) were diagnosed as the homo-HER2 group and 53 patients (61%) were the hetero-HER2 group. After the median follow-up period of 17.8 months, the median PFS and OS were 7.6 and 17.8 months, respectively. Significant survival differences were shown between the two groups; the homo-HER2 group showed significantly longer PFS (10.8 vs. 6.1 months, HR 0.469 95% CI 0.29-0.77, p = 0.003) and OS (29.3 vs. 14.4 months, HR 0.352 95% CI 0.20-0.61, p < 0.001). ORR was 68.6% in this cohort. Higher response rate (85.2% vs 58.1%, p = 0.020) and deeper response (- 49.0% vs - 40.0%, p = 0.018) were also found in the homo-HER2 group.

CONCLUSIONS

Similar to surgical specimens, we verified clinical significance of HER2 heterogeneity on trastuzumab efficacy using endoscopic biopsy specimens.

Clinical relevance of circulating tumor DNA assessed through deep sequencing in patients with metastatic colorectal cancer

Because circulating tumor DNA (ctDNA) studies focusing on only one or a few genes to monitor the disease progress or treatment response are unlikely to find its clinical significance, the development of cell‐free DNA (cfDNA) panel covering hundreds of mutation hot spots is important for the establishment of clinically practical ctDNA detection system. We enrolled 101 patients with metastatic colorectal cancer (mCRC) who received chemotherapy. Amplicon‐based genomic profiling of 14 genes, which are commonly mutated in CRC, in plasma by next‐generation sequencing (NGS) was carried out to evaluate the feasibility of this assay and was compared with their clinical parameters and RAS status in matched tissue samples. Somatic mutations of the 14 genes in plasma cfDNA were detected in 88 patients (87.1%) with mCRC. Mutations in TP53, KRAS, and APC genes were detected in 70 (69.3%), 39 (38.6%), and 24 (23.7%) patients, respectively. Mutant allele frequencies in plasma were significantly associated with metastasis (liver, P = 0.00004, lymph node, P = 0.008, number of metastatic organs, P = 0.0006), tumor markers (CEA, P = 0.000007, CA19‐9, P = 0.006, LDH, P = 0.00001), and tumor diameter (maximum, P = 0.00002, sum of diameter, P = 0.00009). The overall concordance rate of RAS status between ctDNA and matched tissue was 77.2% (78/101). Our data confirmed that mutant allele in cfDNA can be sensitively detected by amplicon‐based NGS system. These results suggest that ctDNA could be a novel diagnostic biomarker to monitor changes in mutational status and tumor burden in patients with mCRC.

Treatment features of systemic chemotherapy in young adults with unresectable advanced or recurrent gastric cancer

Purpose

Gastric cancer in young adults (GCYA) is known to have distinct clinicopathological features, including a female predominance and diffuse-type histology. Previous reports have focused on patients who had undergone gastrectomy with curative intent. Information concerning the treatment of unresectable advanced- or recurrent-stage GCYA is lacking. Therefore, we aimed to investigate whether the distinct clinicopathological features of GCYA affect the outcome of systemic chemotherapy.

Patients and methods

We conducted a retrospective cohort study at a single institution in Japan. GCYA was classified as a disease in individuals who were <40 years of age at diagnosis. Initial systemic chemotherapy regimens for GCYA were investigated with a focus on patients who received S-1 plus cisplatin (SP) as a representative standard regimen. The efficacy, safety, and feasibility of systemic chemotherapy were evaluated.

Results

Eighty-nine (7.5%) of 1,184 consecutive patients who received systemic chemotherapy at our institute between December 2005 and June 2016 were enrolled. As reported previously, the female sex (57.3%) and diffuse-type histology (91.0%) were the dominant features of GCYA. Thirty-two patients (36.0%) received SP as first-line treatment. The median overall survival and progression-free survival times were 13.2 (95.0% CI: 9.5-18.7) and 5.6 (95.0% CI: 4.7-7.9) months, respectively. The median number of treatment cycles, relative dose intensity, and cumulative dose of cisplatin were 4.5 (range: 1-10), 92.0% (IQR: 83.5-98.3), and 286.5 mg/m² (IQR: 172.5-367.5), respectively. The most common adverse event of Grade 3 or higher was neutropenia (n=5 patients; 15.6%). No patient had febrile neutropenia. Non-hematological adverse events of Grade 3 or higher were only observed in 2 (6.3%) of 32 patients.

Conclusion

Standard chemotherapy used for general-aged GC patients has similar efficacy, reduced toxicity, and higher intensity in GCYA patients.

Modified FOLFOX6 as a first-line treatment for patients with advanced gastric cancer with massive ascites or inadequate oral intake

Background

Oral fluoropyrimidine plus platinum is a standard first-line treatment for advanced gastric cancer (AGC). However, this treatment is problematic for AGC patients with massive ascites or inadequate oral intake. This study aimed at evaluating the efficacy and safety of modified oxaliplatin (L-OHP) with l-leucovorin (l-LV) and bolus/continuous infusion of 5-fluorouracil (5-FU) (mFOLFOX6) regimen for patients with massive ascites or inadequate oral intake.

Methods

This retrospective study was conducted at a single Japanese institute from November 2015 to May 2018. The mFOLFOX6 regimen consisted of 85 mg/m² L-OHP, 400 mg/m² bolus of 5-FU, and 400 mg/m² 1-LV on the first day, followed by 2,400 mg/m² of 5-FU as a continuous infusion in 46 hours for first-line treatment. The definition of inadequate oral intake was the need for total parenteral nutrition (TPN). Massive ascites was defined as continuous ascites from the pelvic cavity to the upper abdomen. Improvement in oral intake was defined as no TPN for more than 7 days, and improvement in ascites was defined as a decrease in ascites of more than one grade defined by the Japan Clinical Oncology Study Group trial (JCOG0106).

Results

Among the 364 patients with AGC who received first-line chemotherapy, 17 patients (13 [76.5%] had inadequate oral intake, and four [23.5%] had massive ascites) were enrolled in this study. Median time to treatment failure and overall survival were 4.8 (95% CI=1.5-7.5) and 8.8 months (95% CI=2.3-not available), respectively. Objective improvements in oral intake and ascites were seen in 11 of 13 patients (84.6%) and 6 of 12 patients (50%), respectively. The major grade 3 or 4 adverse events were neutropenia (35.3%), febrile neutropenia (5.9%), fatigue (5.9%), anorexia (5.9%), and infection (5.9%). No treatment-related deaths occurred.

Conclusion

We found that mFOLFOX6 can be a novel treatment option as the first-line treatment for AGC patients with massive ascites or inadequate oral intake.

Clinical impact of intratumoral HER2 heterogeneity on trastuzumab efficacy in patients with HER2-positive gastric cancer

BACKGROUND

There is growing interest in the clinical significance of intratumoral HER2 heterogeneity. Its prognostic and predictive impacts on trastuzumab efficacy were demonstrated in breast cancer. However, its clinical significance in gastric cancer is still unclear.

METHODS

Twenty-eight HER2-positive gastric cancer patients who had gastrectomy prior to trastuzumab-based chemotherapy were consecutively enrolled. Intratumoral HER heterogeneity was evaluated using whole-tissue sections by immunohistochemistry. When all tumor cells overexpressed HER2 protein, the tumor was defined as homogeneously HER2 (Homo-HER2)-positive group. The others were defined as heterogeneously HER2 (Hetero-HER2)-positive group.

RESULTS

There was no significant difference in clinicopathological features between the two groups. The median progression-free survival (PFS) and overall survival (OS) in the Homo-HER2-positive group were significantly longer than those in the Hetero-HER2-positive group (PFS; 20.0 months [95% CI 17.8-22.2] vs. 6.0 months [95% CI 2.3-9.7]; HR 0.11; 95% CI 0.03-0.41; p < 0.001, OS; not reached vs. 14.0 months [95% CI 11.9-16.1]; HR 0.18; 95% CI 0.06-0.61; p = 0.003). In the multivariate analysis, these associations remained significant both in PFS (HR 0.12; 95% CI 0.03-0.46, p = 0.002) and OS (HR 0.21; 95% CI 0.06-0.72, p = 0.013). With respect to response rate, no statistical difference was found between two groups. However, deeper tumor shrinkage was obtained in the Homo-HER2-positive group compared with the Hetero-HER2-positive group (p = 0.046).

CONCLUSIONS

Intratumoral HER2 heterogeneity may have robust clinical impact on trastuzumab efficacy in patients with HER2-positive gastric cancer. These findings should be validated by larger independent cohorts and further molecular correlative analyses are warranted.

Two Cases of Long-Term Survival of Advanced Colorectal Cancer with Synchronous Lung Metastases Treated with mFOLFOX6/XELOX + Bevacizumab

Background

Colorectal cancer (CRC) with lung metastases has an unfavorable prognosis. However, nowadays, even advanced CRC can have a favorable outcome in certain cases. A complete response (CR) is a rare event in advanced CRC with lung metastases. Herein, we report 2 rare cases of advanced CRC attaining a CR.

Case Presentation

Case 1 was a 58-year-old man who underwent laparoscopic ileocecal resection for cecum cancer with multiple metastases to the lungs in 2011. We performed treatment with mFOLFOX6 and bevacizumab chemotherapy in August 2011. After 11 courses, computed tomography (CT) revealed a CR to chemotherapy in February 2012. He has remained disease-free for 5 years and 3 months. Case 2 was a 70-year-old woman who underwent laparoscopic ileocecal resection for cecum cancer in August 2010. Recurrence of multiple metastases to both lungs was detected in November 2010. We started treatment with XELOX and bevacizumab chemotherapy in January 2011. In January 2011, CT after 14 courses revealed disappearance of the lung lesions, thereby indicating a CR. She has remained disease-free for 5 years and 4 months.

Conclusion

We encountered 2 patients with CRC with lung metastases who were treated with chemotherapy leading to a CR. Cases resulting in such a desirable outcome are extremely rare.

Abstract 4580: Changes in the efficacy of anti-EGFR antibody drugs by exosomes derived from colorectal cancer patients

Background: One of the biggest hurdles in cancer treatment is drug resistance. Exosomes are small membrane vesicles of endocytic origin, which contain mRNAs, DNA fragments, and proteins, and are released by many different cell types, including cancer cells. Several studies have shown exosome-mediated drug resistance mechanisms: drug export via the exosome pathway, neutralization of antibody-based drugs and exosome-mediated transfer of miRNAs. Here, we demonstrated the effect of exosomes derived from colorectal cancer (CRC) patients on the efficacy of anti-EGFR agent by in vitro cell-based assay.

Method: Exosomes were purified by ultracentrifugation from culture media of HCT116 cell line and the sera of CRC patients with stage IV pre- and post-treatment with cetuximab (Cmab). As a control, sera from healthy volunteers were used. The number of exosomes and amount of protein were determined by NanoSight and Qubit fluorometer, respectively. The isolated exosomes and 0.01 mg/mL and 0.1 mg/mL of Cmab were added to HT29 and NCI-H508, which stained with PKH dye previously. NCI-H508 is a Cmab super sensitive cell line. After culturing for 3 days, the cells were collected, stained with trypan blue, and the number of the remaining viable cancer cells was calculated with a cell counter. Cmab in the exosome fraction was quantified by ELISA.

Result: HT29 became drug ineffective depending on the number of exosomes produced by Cmab-insensitive HCT-116 harboring KRAS G13D mutation. In addition, exosomes in 9 of 18 cases of colorectal cancer patients changed NCI-H508 into a drug-ineffective state and also correlated with clinical information. In contrast, NCI-H508 was not converted into a drug-ineffective state by exosomes of healthy volunteers and Cmab responder patients. However, on the other hand, quantitative results by ELISA showed that Cmab in sera of some patients remained in the exosome fraction and inhibited the growth of NCI-H508. As a remarkable point, exosomes derived from healthy volunteers significantly promoted the efficacy of Cmab.

Conclusion: In this feasibility study, Cmab resistance in CRC patients may be reproducible by cell-based assay using exosomes. We believe that understanding this mechanism of action will contribute to drug discovery and personalized medicine in the future. Now, we are searching for biomarkers in these exosomes that change the efficacy of Cmab.

Citation Format: Rii Morimura, Kei Tsukamoto, Shinji Irie, Shiro Kitano, Eiji Shinozaki, Kensei Yamaguchi. Changes in the efficacy of anti-EGFR antibody drugs by exosomes derived from colorectal cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4580.

Abstract 5016: A unique ex vivo drug evaluation model: 3D co-cultured system with tumor, stroma and blood microvessels

Background; Two dimensional single-layer culture still remains the preferred platform for most laboratory preclinical studies, although interaction between cancer and stromal cells has been well reported to be important in tumor progression and resistance against therapies. In order to mimic the patient tumor tissues, ex vivo model which recaptures the tumor microenvironment is required.

Methods; Layered 3D stromal tissues were produced by culturing normal human dermal fibroblasts (NHDFs) and human umbilical vein endothelial cells (HUVECs) coated with extra-cellular matrix (ECM) and natural polysaccharide, namely collagen and heparin. The layered 3D stromal tissues and overlaid tumors were morphologically characterized by HE stain, immunohistochemistry (IHC) and immunofluorescence (IF). Furthermore, drug sensitivity assays were conducted using popular colorectal cancer cell lines, and patient-derived cell lines (PDCs) established in the laboratory of Japanese Foundation for Cancer Research. Cancer cell viability was evaluated by fluorescent labeling, enzymatic dissociation and cell counting analysis. IF with cancer specific markers and imaging analyses were also performed.

Results; The 3D stromal tissues including CD31 positive luminal structure were multi-layered (approximately 20 layers), and formation of microvascular network was observed within several days. In comparison with 2D mono-culture or 3D mono/co-cultured spheroid model, decreased drug sensitivities were represented in our 3D co-cultured model. In the simultaneous treatment with cytotoxic anticancer agents and molecular targeted drugs, dose-responses were significantly different between the2D and 3D models.

Conclusion; We developed the layered 3D stromal tissue culture system including blood micro-vessels. Drug evaluation with the co-cultured tumors may reflect the drug sensitivity of cancer cells in vivo. Our unique 3D ex vivo model represents a valuable tool for drug development in a fully human cell and matrix microenvironment, and thus testing patient-derived cells and approved compounds also enable better prediction their efficacy.

Citation Format: Yuki Takahashi, Kei Tsukamoto, Shiro Kitano, Shinji Irie, Michiya Matsusaki, Satoshi Nagayama, Ryohei Katayama, Eiji Shinozaki, Naoya Fujita. A unique ex vivo drug evaluation model: 3D co-cultured system with tumor, stroma and blood microvessels [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5016.

Abstract 1151: A unique layered 3D stromal tissue model for in vitro evaluation of immunologic agents and immune cell infiltration into cancer microenvironment

Background; The modulation of the immune system is a proven key target for cancer therapy, however, the complex interplay between immune cells and cancer cells in cancer microenvironment remains only partially understood. In addition, the currently available in vitro cancer microenvironment models are not designed to study the immunologic agents and a role of immune cells. Here, we developed a unique layered 3D stromal tissue model comprising an allogeneic immune, stromal and cancer cells.

Method; Human umbilical vein endothelial cells (HUVEC) and normal human dermal fibroblasts (NHDF) were coated with collagen and heparin to construct Extracellular matrix (ECM) nanofilm and cultured to form multi-layers. Lung cancer cells were placed between stromal cells. Furthermore, we added Peripheral Blood Mononuclear Cell (PBMC) and Programmed cell death 1 (PD-1) blockade with Nivolumab and evaluated cytotoxic effects of immune cells on cancer cells and immune cell infiltration by immunohistochemistry.

Result; The co-cultured stromal tissues were multi-layered (approximately 20 layers), and the presence of lung cancer cells between stromal cells was observed. Immunohistochemistry revealed CD8 positive immune cell infiltration into the fibroblast layers. PBMC with Nivolumab treatment significantly decreased the viability of lung cancer cells in this 3D co-culture compared with the results in 2D mono-culture. High level of programmed cell death ligand 1 (PD-L1) expression on lung cancer cell lines correlated with a higher response to PD-1 blockade in vitro as well as clinical trials.

Conclusion; In summary, we present a unique 3D cell culture system based on an allogeneic stromal/cancer/immune cell setting to study immunologic agents and immune cell infiltration in cancer microenvironment. This 3D model has the ability to reflect in vivo conditions closer than 2D model and provide a tool for in vitro immunologic agent testing.

Citation Format: Rii Morimura, Kei Tsukamoto, Shiro Kitano, Eiji Shinozaki. A unique layered 3D stromal tissue model for in vitro evaluation of immunologic agents and immune cell infiltration into cancer microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1151.

Abstract 2962: Clinical relevance of circulating cell-free DNA using amplicon-based next-generation sequencing panel in colorectal cancer patients with liver metastasis

Background: Recent advances in the next-generation sequencing technique (NGS) for the detection of cell-free DNA (cfDNA) will be possible to provide the utility as diagnostic and prognostic biomarkers of cancer. We conducted the study of feasibility to detect plasma cfDNA from patients with metastatic colorectal cancer (mCRC) using NGS panel and investigated their relationship with clinicopathological factors.

Methods: A total of 101 mCRC patients with liver metastasis, who had been treated with chemotherapy, were enrolled in this study from February to June in 2017. We investigated i) frequency of detectable mutations in plasma cfDNA, ii) concordance rate of RAS mutation between the DNA extracted from tissues and the plasma cfDNA, iii) relationship between the mutation allele frequencies (MAF) and clinicopathological factors including tumor location, metastatic site, number of metastatic organs, tumor marker (CEA and CA19-9), LDH level, D-dimer level and sum of the tumor diameter measured based on RECIST ver1.1 criteria. Sequencing of plasma cfDNA were performed using Ion Torrent™ Oncomine™ Colon cfDNA Assay.

Results: Mutations in plasma cfDNA were detected in 87.1% (88/101) of patients. The frequencies of plasma cfDNA mutation at TP53, KRAS, APC, and PIK3CA were 68.3%, 38.6%, 23.7%, and 14.8%, respectively. RAS mutational concordance rate between DNA extracted from tumor and cfDNA was 76.2% (77/101). MAF were significantly associated with CEA (P&lt;0.0001), CA19-9 (P=0.006), LDH (P&lt;0.0001) and number of metastatic organs (P&lt;0.0001). Patients with liver or lymph node metastasis had significantly higher MAF compared with those without metastases (Liver: P&lt;0.0001, Lymph node: P=0.008). Positive correlations between CEA level, CA19-9 level, LDH level, tumor diameter and MAF were observed. (CEA: r=0.52, CA19-9: r=0.34, LDH: r=0.55, tumor diameter: r=0.57)

Conclusions: Our results suggested that this cfDNA Assays could detect mutations at a high rate of mCRC patients undergoing chemotherapy and cfDNA analysis using NGS panel could be useful method of diagnostic biomarkers to monitor the change of RAS status and tumor burden. &lt;!–EndFragment–&gt;

Citation Format: Hiroki Osumi, Eiji Shinozaki, Hitoshi Zembutsu, Yoshinori Takeda, Takeru Wakatsuki, Takashi Ichimura, Yumiko Ota, Izuma Nakayama, Mariko Ogura, Mitsukuni Suenaga, Daisuke Takahari, Keisho Chin, Akio Saiura, Kensei Yamaguchi. Clinical relevance of circulating cell-free DNA using amplicon-based next-generation sequencing panel in colorectal cancer patients with liver metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2962.

Abstract 1954: Functional analyses of CLDN18-ARHGAP26 fusion gene in gastric cancers

[Introduction]Comprehensive molecular analyses by TCGA have classified Gastric Cancers (GC) into 4 groups: EB virus -associated (EBV), Microsatellite instability (MSI), Genomically stable (GS) and Chromosomal instability (CIN). Among these 4 subtypes, patients with GS subtype have few actionable genetic alterations and thus a limited number of molecular-targeted treatments are available. A fusion gene between CLDN18 and ARHGAP26 was first reported by TCGA to be enriched in GS subtype (13.8%), but the prospective functions of this gene product remain unknown.

[Methods]We have previously established 124 GC-Patient derived xenografts (PDXs) from surgically resected specimens in our institute. There are various types of GCs in the PDX panel, including intestinal and diffuse type tumors or tumors of primary and metastatic site. In an attempt to assess roles of CLDN18-ARHGAP26 fusion gene in gastric cancers, we used the cultured cells obtained from GC-PDXs. We first prepared tissue micro-array of formalin-fixed and paraffin-embedded (FFPE) specimen of PDXs and screened for the patients harboring a CLDN18-ARHGAP26 fusion genes by FISH and RT-PCR. In addition, fusion positive cases were sequenced to determine the breakpoints by direct sequencing. Then, we conducted several functional analyses, including assays for cellular proliferation and mobility, by RNAi-knockdown experiments.

[Results]Among 124 GC-PDXs, we detected two CLDN18-ARHGAP26 fusion positive cases. Both of these 2 cases were derived from tumors with diffuse-type GC patient and had identical breakpoint between CLDN18 (exon 5) and ARHGAP26 (exon 10). We successfully established cell lines of these 2 cases. Furthermore, we would verify that PDX derived cells preserved the original patient properties, as transplantation of the PDX-derived cells histologically recapitulated the original tumors. To address its function, we introduced siRNA into cultured cells to reduce their protein levels. Our data so far indicate that the CLDN18-ARHGAP26 fusion might promote anchorage independent cell growth.

[Conclusion] The CLDN18-ARHGAP26 fusion gene potentially contributes to malignant phenotypes of GC. Further analyses in vivo are awaited.

Citation Format: Izuma Nakayama, Eiji Shinozaki, Tetsuo Mashima, Tokuichi Kawaguchi, Seiji Sakata, Noriko Yamamoto, Satoko Baba, Akito Dobashi, Yuki Togashi, Minoru Sugawara, Shunji Takahashi, Kensei Yamaguchi, Kengo Takeuchi, Tetsuo Noda. Functional analyses of CLDN18-ARHGAP26 fusion gene in gastric cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1954.

Phase II trial of biweekly cetuximab and irinotecan as third-line therapy for pretreated KRAS exon 2 wild-type colorectal cancer

Efficacy and safety of biweekly cetuximab plus irinotecan were evaluated to provide guidance for its use in Japan as third-line treatment for pretreated metastatic colorectal cancer (mCRC) patients harboring wild-type KRAS exon 2. Objective response rate (ORR) was used as primary endpoint based on an expected proportion of 0.23 with confidence width of 0.298 (95% CI, 0.105-0.403), which showed 35 to be the minimal participant number. Forty patients, refractory to first- and second-line chemotherapy containing irinotecan, oxaliplatin, and fluoropyrimidine, were enrolled. ORR and disease control rate were 25.0% (95% CI: 11.5-38.4) and 72.5% (95% CI: 56.8-86.4), respectively. Median progression-free survival (PFS), overall survival (OS), and number of courses were 5.70 months (95% CI: 2.7-7.9), 15.1 months (95% CI: 11.8-19.0), and 10.5 (range: 3.0-31.0), respectively. Grade 3 adverse events were skin toxicity (12.5%), diarrhea (10.0%), neutropenia (5.0%), febrile neutropenia (5.0%), nausea (5.0%), anorexia (5.0%), and fatigue (2.5%). C_max mean was 723.2 μg/mL after first dose. High area under the curve (AUC)_last variance was associated with t_1/2 range of 131.2-1209.6 hours (median, 174.4 hours). Early tumor shrinkage (ETS) and median depth of response were 25.0% and 13.0%, respectively. Mutation frequencies in KRAS exon 3 or 4, NRAS, BRAF, and PIK3CA were 5.5%, 2.7%, 8.3%, and 5.5%, respectively. Multivariate Cox regression analysis assessed whether any gene mutations and ETS are predictors for PFS, and whether performance status, synchronous metastasis, and ETS are predictors for OS. Importantly, the data provide guidance for a biweekly cetuximab plus irinotecan regimen in mCRC patients.

Serum leucine-rich alpha-2-glycoprotein-1 with fucosylated triantennary N-glycan: a novel colorectal cancer marker

BACKGROUND

Carcinoembryonic antigen (CEA) and carbohydrate antigen (CA)19-9 are used in clinical practice as tumor markers to diagnose or monitor colorectal cancer (CRC) patients, However, their specificities and sensitivities are not ideal, and novel alternatives are needed. In this study, mass spectrometry was used to search for screening markers, focusing on glycan alterations of glycoproteins in the sera of CRC patients.

METHODS

Glycopeptides were prepared from serum glycoproteins separated from blood samples of 80 CRC patients and 50 healthy volunteers, and their levels were measured by liquid chromatography time-of flight mass spectrometry (LC-TOF-MS).

RESULTS

Leucine-rich alpha-2-glycoprotein-1 with fucosylated triantennary N-glycan (LRG-FTG) was identified as CRC marker after evaluating 30,000 candidate glycopeptide peaks. The average LRG-FTG level in CRC patients (1.25 ± 0.973 U/mL) was much higher than that in healthy volunteers (0.496 ± 0.433 U/mL, P < 10^- 10), and its sensitivity and specificity exceeded those of CA19-9. The combination of CEA and LRG-FTG showed a complementary effect and had better sensitivity (84%), specificity (90%), and AUC (0.91 by ROC analysis) than each marker alone or any other previously reported marker. LRG-FTG alone or combined with CEA also corresponded well with patient response to treatment.

CONCLUSIONS

We identified LRG-FTG as a new CRC marker, with a sensitivity and specificity exceeding CA19-9. The combination of LRG-FTG and CEA showed much higher sensitivity and specificity than each marker alone. Further validation beyond this initial exploratory cohort is warranted.

Early hypertension is associated with better clinical outcomes in gastric cancer patients treated with ramucirumab plus paclitaxel

Anti-vascular endothelial growth factor (VEGF) therapeutics such as bevacizumab, which are widely used in cancer treatment, commonly leads to hypertension. Moreover, bevacizumab-induced hypertension is associated with improved clinical outcomes in several cancers. We retrospectively analyzed 89 patients with histologically confirmed advanced gastric cancer who received the human monoclonal anti-VEGF receptor-2 antibody ramucirumab plus paclitaxel at our hospital between June 2015 and October 2016 to evaluate the impact of treatment-associated hypertension occurring within the first two treatment cycles ("early hypertension") on outcome. The objective response rate was 40%, median progression-free survival was 5.4 months, and overall survival was 10.4 months, which is similar to previous reports. Early hypertension in patients who received more than two cycles of ramucirumab + paclitaxel was associated with longer progression-free and overall survival. Objective response rates were also higher in patients with early hypertension. These data indicate that early hypertension may be predictive of better outcomes in gastric cancer patients who receive ramucirumab + paclitaxel treatment.

A Feasibility Study of Capecitabine and Oxaliplatin for Patients with Stage II/III Colon Cancer -ACTOR Study

BACKGROUND/AIM

Past studies have suggested that adjuvant capecitabine and oxaliplatin (CAPOX) provides decreased tumor relapse and longer survival in patients with curatively resected colon cancer. We report the first evidence of the feasibility of adjuvant CAPOX in Japanese patients with early colon cancer.

PATIENTS AND METHODS

Eligible patients had histologically-confirmed stage II/III colon cancer and received curative resection. The primary endpoint was completion rate of treatment after 8 cycles of adjuvant CAPOX.

RESULTS

Thirty-six patients were enrolled in this study. The completion rate of CAPOX and oxaliplatin were 77.8% and 61.1%, respectively. The incidence of grade ≥3 adverse events was neutropenia (n=6), thrombocytopenia (n=3), nausea (n=5), hand-foot syndrome (n=1) and peripheral sensory neuropathy (n=1). Three-year disease-free survival for stage II patients and stage III patients were 100% and 79.3%, respectively.

CONCLUSION

Adjuvant CAPOX can be safely administered to Japanese patients with stage II/III colon cancer.

Associations between early tumor shrinkage and depth of response and clinical outcomes in patients treated with 1st-line chemotherapy for advanced gastric cancer

BACKGROUND

Although early tumor shrinkage (ETS) predictions of the efficacy and depth of response (DpR) reflects clinical outcomes in chemotherapy with epidermal growth factor receptor inhibitor regimens to treat metastatic colorectal cancer, their value in assessing treatments for advanced gastric cancer (AGC) is unclear. Here we evaluated relationships between ETS and DpR and clinical outcomes in AGC patients treated with first-line chemotherapy.

METHODS

We retrospectively enrolled 612 consecutive patients treated with first-line chemotherapy for AGC between January 2010 and June 2016. ETS and DpR were defined as changes from baseline in summed longest diameters in target lesions at 8 (±4) weeks for ETS and at the smallest observed volume for DpR.

RESULTS

Eligible patients were sorted into HER2⁺ (n = 100) and HER2^- (n = 186) groups. Median follow-up was 14.8 months. The overall response rate and disease control rates were 64 and 87% in the HER2⁺ group and 53.2 and 86.0% in the HER2^- group. Respective median PFS and OS were HER2⁺: 7.9 and 20.8 months and HER2^-: 6.6 and 13.8 months. The respective ETS rate and median DpR were HER2⁺: 70 and 44% and HER2^-: 57.5 and 24%. Clinical outcomes and ETS/DpR were correlated, especially in the HER2⁺ group (OS: P < 0.0001; PFS: P < 0.0001). In multivariate analysis, ETS was an independent predictor for OS in the HER2⁺ group and for PFS in both groups.

CONCLUSION

These results indicate that ETS may be an early-on treatment predictor of the efficacy of HER2⁺ advanced gastric cancer treated with first-line chemotherapy that includes trastuzumab.

Plasma biomarker analysis of ramucirumab in Japanese patients with advanced gastric cancer

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Background: Ramucirumab, anti-VEGFR2 receptor antibody, showed significantly improved survivals of gastric cancer in the second line with paclitaxel or single use. Recently we reported early elevation of plasma VEGF-A was associated with shorter survival as a preliminary result. We will report the results of final analysis. Methods: Patients with advanced gastric cancer who received ramucirumab combined with paclitaxel or single use were enrolled. Plasma samples were collected at pre-treatment and day 8 after administration. Nine kinds of plasma biomarker involved in angiogenesis, VEGF-A, C, D, PlGF, VEGFR1, 2, Angiopoietin 1, stromal cell derived factor-1α (SDF1α), and Neuropirin-1, were measured by means of ELISA. Patients were dichotomized by optimal cut-off value. Univariate and multivariate analysis were done by Cox proportion hazard model. Results: Forty-one patients were enrolled. Thirty-nine patients (95.1%) received ramucirumab with paclitaxel. Plasma VEGF-A, D, PlGF, and VEGFR2 levels were significantly increased one week after administration compared with baseline levels, while plasma VEGFR1 and NRP1levels were significantly decreased. Median PFS and OS were 5.6 (95% CI 4.66-6.54) and 9.8 (95% CI 5.41-14.19) months, respectively. In univariate analysis, higher baseline SDF1α and PlGF levels resulted in shorter OS with HR 2.71 95% CI 1.23-6.00, p =0.013 for SDF1α and HR 2.78 95% CI 1.16-6.65, p =0.022 for PlGF. Higher D8 VEGF-A was associated with shorter PFS with HR 2.77 95% CI 1.39-5.51, p =0.004. While higher D8 VEGF-D was associated with better PFS with HR 0.39 95% CI 0.20-0.77, p =0.007. In multivariate analysis, higher baseline SDF1α and PlGF were independent negative prognostic factor for OS with HR 2.45 95% CI 1.10-5.42, p =0.028 for SDF1α and HR 2.48 95% CI 1.03-5.96, p =0.043. With respect to PFS, higher D8 VEGF-A was also independent negative prognostic factor with HR 2.32 95% CI 1.13-4.77, p =0.022, while higher D8 VEGF-D was favorable predictor for PFS with HR 0.47 95% CI 0.23-0.96, p =0.038. Conclusions: Higher base line SDF1α and PlGF levels may be negative prognostic marker. While early VEGF-A and D elevation after ramucirumab administration may be predictive marker of ramucirumab.

A retrospective analysis of ramucirumab monotherapy in previously treated Japanese patients with advanced or metastatic gastric adenocarcinoma

BACKGROUND

The REGARD trial demonstrated that ramucirumab monotherapy improved both overall survival (OS) and progression-free survival (PFS) compared with best supportive care plus placebo as second-line treatment for patients with advanced gastric cancer. However, the efficacy and safety of ramucirumab monotherapy for previously treated Japanese patients with advanced gastric cancer remains unknown.

METHODS

Previously treated Japanese patients with advanced gastric cancer who received ramucirumab monotherapy between June 2015 and March 2016 at the Cancer Institute Hospital were enrolled in the study. OS, PFS, best overall response, and safety profiles were retrospectively evaluated.

RESULTS

Nineteen patients were enrolled in this study. Ramucirumab monotherapy was generally administered as third-line therapy. After a median follow-up period of 7.4 months, the median PFS was 2.1 months (95% CI 1.0-3.5), and median OS was 12.9 months (95% CI 2.3, not reached). In 13 patients who had measurable lesions on radiologic examination, partial response was observed in one patient (7.7%) and stable disease was observed in five patients (38.5%). A total of 12 patients (63.2%) had adverse events (AEs). Common AEs included hypertension (8 patients, 42.1%), fatigue (6 patients, 31.6%), and bleeding (5 patients, 26.3%). Grade 3 AEs included gastrointestinal bleeding and aspiration pneumonia (1 patient each, 5.3%).

CONCLUSIONS

Our data suggest that ramucirumab monotherapy in Japanese patients with previously treated advanced gastric cancer has comparable efficacy and safety profiles as reported in the REGARD trial.

The clinical analysis of thromboembolism in esophagogastric cancer in Japan: A single institute experience

14

Background: Although patients with esophagogastric cancer have a higher risk of thromboembolism (TE), the clinical characteristics of esophagogastric cancer patients with TE remain unclear. Methods: We conducted a retrospective study of who were treated for TE in our institution from January 2014 to August 2017. Results: During this period, 1538 esophaogastic cancer patients received anti cancer therapy. Of these 62 (4.0%) patients diagnosed as having TE during their clinical course. Background of these patitents were median age :64.5 (28-87), gender male/ female: 36 /26, 47 had gastric cancer, 12 esophageal cancer, and 2 gastroesophageal cancer. Performance Status were 0/1/2/3 = 21/24/13/4. Clinical stage were Ⅳ 32 (metastatic sites; lymph nodes 7, peritoneal dissemination 6, ovary 4, liver 1), recurrence 18, and other 12 respectively. 26 patients did not have medical history, 15 had hypertension, 4 had diabetes mellitus, and 4 had hyperlipidemia. Pathologically, adenocarcinoma 50, squamous carcinoma 10, and other 2. Among patients with gastric cancer, 6 (12.8%) showed Her2 overexpression. The median D-dimer levels was 4.81(0.42-17.25) μg/ml. The onset of TE was before starting chemotherapy in 8(12.9%), during receiving chemotherapy in 48(77.4%), and during washout period in 6. On patients who developed TE during receiving chemotherapy, the regimens of chemotherapy were S-1 16, weekly paclitaxel 10 (plus ramucirumab 3), SOX 7, FP 4, Irinotecan 3, SP 3, FOLFOX 3, XP+Trastuzumab3, and others 9. The types of venous thrombosis were deep vein thrombosis 33, pulmonary embolism 23, central venous catheter 7, internal jugular vein 5, subclavian vein 4, and others 5. Four patients suffered cerebral infarction due to thrombosis of the arterial system thrombosis. Initial anticoagulation treatment for TE were heparin 33, warfarin 13, edoxaban 12 and other 4. 29 patients (46.8%) had no symptom related TE. Conclusions: In our analysis, 12.9% patients had TE before starting treatment, we should pay attention to TE immediately after diagnosis of esophagogastric cancer. As 46.8% patients have no symptom related TE, it is important to develop of biomarkers for screening TE, likely D-dimer.

Multicenter phase I/II trial of BBI608 and pembrolizumab combination in patients with metastatic colorectal cancer (SCOOP Study): EPOC1503

760

Background: The anti–programmed death 1 (PD-1) antibody, pembrolizumab provided an objective response rate (ORR) of 40% in patients (pts) with Mismatch Repair–Deficient (dMMR) or Microsatellite Instability–High (MSI-H) metastatic colorectal cancer (mCRC) vs 0% in pts with MMR-proficient/Microsatellite Stable (MSS) mCRC. The WNT/β-catenin signaling has been reported to prevent anti-tumor immunity and promote resistance of anti-PD-1/PD-L1 antibodies. This study investigates efficacy and safety of the combination of BBI608, which blocks phosphorylated STAT3 and downregulates WNT/β-catenin signaling, with pembrolizumab in pts with mCRC (both MSS and MSI-H). Here, we present the results of the phase I part. Methods: Phase I part was designed to determine the recommended phase II dose (RP2D) in a “3+3” cohort-based dose escalation design of BBI608 (240mg BID every day on level 1 and 480mg BID every day on level 2) with pembrolizumab (200mg/body q3w). We also conduct biomarker research using paired samples from repeated tumor biopsies and blood collections. Results: Five pts were enrolled in level 1, and 3 pts in level 2. All pts were MSS mCRC. Seven pts were included in the safety analyses. Two pts in level 1 were excluded from dose-limiting toxicity (DLT) evaluation because of disease progression during DLT evaluation period. No DLTs were observed at either level. Grade 3 or worse treatment-related adverse events (TRAEs) were not observed. Grade 1 or 2 TRAEs included diarrhea related to BBI608 (57%), hyperthyroidism (14%), hypothyroidism (14%), and fever (14%) without unexpected safety signals. One patient in level 2 showed a tumor shrinkage lasting more than 12 weeks for lung and lymph node metastases with remarkable decline of CEA level. Analysis of repeated tumor samples from this case demonstrated that CD8+ T-cells infiltration inside the tumor on treatment was observed by immunohistochemistry and flow-cytometry. Conclusions: BBI608 480mg BID with pembrolizumab was tolerable and determined as RP2D. This combination showed a hint of activity and might evoke immunity in MSS mCRC, which will be confirmed by ongoing phase II part. Clinical trial information: NCT02851004..

Association of malignant potential of BRAF mutant colorectal cancer with coexpression of PD-L1

643

Background: PD-L1 is a member of the B7/CD28 family that regulates immune response, and also well known as targets for immune checkpoint inhibitor. On the other hand BRAF mutation (MT) is recognized as a strongly poor prognostic factor in colorectal cancer (CRC). Recently in addition to the RAS gene, a lot of new knowledge about some molecules playing an important role in the process of carcinogenesis or drug resistance, and emerging molecules as targets for new treatments have been reported. In this research, we aim to address the clinical significance of PD-L1 expression in colorectal carcinoma correlation between emerging molecules and differences through clinical stages in CRC using tissue array. Methods: Consecutive patients who underwent surgery in our hospital from June 2003 to March 2011 were enrolled in this study. Tissue array based profiling of emerging molecules was performed on archival samples using immunohistochemistry for BRAF, MLH1/MSH2/MSH6/PMS2, CDX2, HER2 and PD-L1. We analyzed PD-L1 expression and correlation with molecular profile, survival, clinicopathological findings and location of primary site. Results: A total of 1030 CRC from stage 0 to IV were analyzed. The expression rates of PD-L1 were 3.6% and increased significantly in BRAF MT, dMMR, lack of CDX-2, tumor grade3 (TG3), right sided colon of primary site (25%, 37.8%, 21.6%, 22.1%, 6.9%, respectively; P < 0.001). In the univariate analysis, lack of CDX2, BRAF MT and TG3 were identified as prognostic factors in whole population of this cohort. Furthermore the survival of BRAF MT and lack of CDX2 with co-expression of PD-L1 were extremely poor (median OS in stage IV; 2.6 months in both). In Particular the co-expression rates of PD-L1 in BRAF MT were increasing as the clinical stage progress regardless of dMMR. Conclusions: Our study comprehensively summarized the significance of PD-L1 expression associated with the recent emerging molecules and suggested that malignant potential of BRAF mutant CRC may be explained in part due to escape from immunity by co-expression of PD-L1. Immune checkpoint inhibitor could be a candidate of target of BRAF mutant CRC with PD-L1expression irrespective of MSI status.

Clinical outcomes of anti-EGFR antibody treatment for right-sided colon cancer patients without RAS, BRAF, and PIK3CA mutations in the later line

812

Background: Several studies have reported that patients with right-sided colon cancers (RCC) have more unfavorable responses to anti-epidermal growth factor receptor (EGFR) antibody therapy than those with left-sided colon cancers (LCC). One of the causes is that RCC have more frequently genetic mutations such as RAS, BRAF, and PIK3CA than LCC. We investigated clinical outcomes of RCC patients treated with anti-EGFR antibody in the later line without these mutations. Methods: We reviewed 653 cases of colorectal cancer treated with anti-EGFR antibody from October 2009 to July 2017. There were 150 cases of RCC patients. Among them, 32 patients without KRAS status and 54 patients without enough genetic samples for gene re-analysis were excluded. We extracted 64 patients with status on RAS, BRAF, and PIK3CA , and finally enrolled 25 patients treated with anti-EGFR antibody plus irinotecan or anti-EGFR antibody alone in the later line. We analyzed the relationship of molecular status with clinical outcomes; overall response rate (RR), overall survival (OS) and progression-free survival (PFS) in this retrospective study. Results: Overall, there were 48% of cases with any mutations; among them 8.0% for KRAS, 4.0% for NRAS, 24.0% for BRAF and 4.0% for PIK3CA. Twenty percent of patients were treated as 2nd line therapy, while 72%, 16% treated as 3rd, 4th line therapy. RR of all cases, those whom without KRAS, RAS, RAS or BRAF, any mutations were 16.0%, 19.1%, 20.0%, 28.6%, 30.8%. The median OS and PFS in all wild-type patients were tended to be better than in those of all cases (OS; 14.9 vs. 11.6 months, hazard ratio = 0.70, p = 0.30, PFS; 8.17 vs. 5.37 months, hazard ratio = 0.67, p = 0.24). Conclusions: Even if primary tumors are in right-sided colon, in the enriched and selected patients anti-EGFR antibody therapy showed enough antitumor activity. Anti-EGFR antibody for RCC cases without using it at the front line is an effective option in the later line.

Chemoradiation for the treatment of locoregional squamous cell carcinoma of the anal canal: A single center retrospective analysis in Japan

851

Background: Squamous cell carcinoma of the anal canal (SCCA) is a rare malignancy. In western countries, chemoradiotherapy (CRT) has become the standard treatment for locoregional SCCA according to National Comprehensive Cancer Network guidelines. But only some small amount case reports have been found about CRT for SCCA in Japan. We retrospectively evaluated the results of CRT for SCCA at a single center in Japan. Methods: We had treated 33 patients with the concurrent CRT at the Cancer Institute Hospital between 2007 and 2017. RT consisted of 45.0 to 59.4 Gy given in 5 to 7 weeks, with a daily dose of 1.8 Gy. Chemotherapy was given during RT: 1000mg/m2 daily fluorouracil (FU) as a continuous infusion on day 1 to 4 and 29 to 32, and a single dose of mitomycin C (MMC) 10mg/m2 administered on day 1 and 29. Data on relapse and deaths were obtained until August 2017. Results: Of 33 patients who were treated with CRT, the median age was 59 (range 35-82) years. Male to female sex ratio was 1:4.5. Patients who had Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0 were 88% and patients who had ECOG PS 1 were 12%. The clinical stages before CRT were cStage I in 9 (27%), II in 4 (12%), IIIA in 6 (18%) and IIIB in 14 (42%). Although clinical complete response (CR) was observed in 29 patients of 33 (88%), 5 patients of 29 recurred. No patients recurred in cStage I and II. SCCA remained or recurred in 2 patients of 6 in cStage IIIA and 7 patients of 14 in cStage IIIB. 3-year disease free survival (DFS) was 71.3% (95%CI: 52.0-84.0%), and 3-year overall survival was 81.8% (95%CI: 55.1-92.8%). Conclusions: CRT for SCCA resulted in clinically meaningful impact on DFS and OS in our hospital. Therefore, CRT may be the standard of treatment also in Japan.

Identification of biomarkers for TAS-102 efficacy in metastatic colorectal cancer patients based on preclinical analysis and clinical validation

669

Background: Trifluridine (FTD) incorporation into DNA is the main anti-tumor mechanism of action of TAS-102. We performed preclinical analysis and translational validation study to identify the candidate cytokines for TAS-102 efficacy in metastatic colorectal cancer (mCRC) patients (pts). Methods: As a first preclinical process, we selected candidate cytokines according to our transcriptomic and cell biological analysis. We then validated predictive value of the cytokines in mCRC pts receiving TAS-102 (discovery) and regorafenib (control). Blood samples were obtained at baseline (BL), before second cycle (2nd) and progressive disease (PD), and cytokine levels were measured using ELISA. The change patterns were defined as ‘increased’ or ‘decreased’ from BL. Results: 93 pts were included in this study: 67 received TAS-102 and 26 received regorafenib. Preclinical cDNA microarray analysis with colon cancer cell lines demonstrated marked changes in the RNA expression of interleukin-8, VEGF-A and epiregulin (EREG) after FTD treatment. Particularly, in preclinical model, EREG secretion was highly measured after FTD treatment in FTD-sensitive cells, while not in FTD-resistant cells. In the discovery cohort, increased EREG levels at 2nd showed trend toward longer PFS and OS than decreased changes (2.6 vs 2.3 mos, P= 0.096; 10.8 vs 6.2 mos, P= 0.091). Meanwhile, decreased EREG levels at PD were marginally associated with longer PFS and significantly with longer OS than increased (4.0 vs 2.3 mos, P= 0.130; 9.8 vs. 6.2 mos, P= 0.016). Combined analysis of EREG changes showed that pts with either increased at 2nd or decreased at PD had significantly longer PFS and OS compared to those with both decreased at 2nd and increased at PD (3.0 vs 2.0 mos, HR: 0.47, 95%CI: 0.24-0.93, P= 0.031; 10.8 vs 5.3 mos, HR: 0.30, 95%CI: 0.14-0.61, P= 0.001). The findings were confirmed in the multivariate analysis for OS (HR: 0.311, 95%CI: 0.15-0.66, P= 0.002), and no significant differences were observed in the control cohort. Conclusions: Our preclinical data-based translational validation study suggests that serum EREG levels may predict clinical outcome in mCRC pts receiving TAS-102.

Clinical impact of diverting ileostomy on the dose intensity of adjuvant chemotherapy for colorectal cancer

867

Background: CAPOX as adjuvant chemotherapy is a standard care option for stage III and high risk stage II colorectal cancer(CRC). And then chemotherapy induced diarrhea (CID) is known as one of the dose-limiting toxicities for CAPOX. Although diverting ileostomy is useful for preventing serious complications of high risk anastomosis, it is well recognized that high ileostomy output is hard to manage. Furthermore, the effect of diverting ileostomy on CID of adjuvant chemotherapy is unclear. In this study, we addressed the clinical impact of diverting ileostomy on the dose intensity of adjuvant chemotherapy for CRC. Methods: Patients who diagnosed with stage III colon cancer and stage II or III rectal cancer after curative surgery and received CAPOX as adjuvant chemotherapy during 2011- 2014 were reviewed retrospectively. We investigated the relationship between diverting ileostomy and dose intensity, toxicities and disease-free survival (DFS). Results: 112 patients (median age 60 years, 52% male, 69% colon cancer, 63% stage III, median follow-up 47 months) were enrolled in this study. Of 112 patients, 100 patients were received chemotherapy without ileostomy (non-ileostomy group: NIG) and 12 patients were received chemotherapy with ileostomy (ileostomy group: IG). 112 Patients received 870 chemotherapy cycles. All treatment related grade 3/4 adverse events were documented in 39% of patients in NIG and 33% of patients in IG (P = 0.77). Grade 3/4 of CID occurred in 8% of patients in NIG and 8% of patients in IG (P = 1). Grade 3/4 of neutropenia were recognized in 21% of patients in NIG and 17% of patients in IG (P = 1). Average relative dose intensity (RDI) in NIG were 75.7% and 85.8% for capecitabine and oxaliplatin, respectively. Average RDI of capecitabine and oxaliplatin in IG were 76.1% and 82.7%, respectively. Significant difference of RDI of capecitabine and oxaliplatin were not shown in comparison between NIG and IG (P = 0.93, P = 0.63). The 3-year DFS rate was 85.0% in NIG and 75.0% in IG. The HR for DFS for NIG compared to IG was 1.709 (95% CI, 0.49 to 5.95; P = 0.40). Conclusions: The presence of diverting ileostomy does not affect RDI of CAPOX as adjuvant chemotherapy.

Plasma biomarker dynamics following ramucirumab treatment and survival analysis after ramucirumab treatment failure in patients with advanced gastric cancer

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Background: Ramucirumab (RAM) showed significantly improved survivals of gastric cancer in the second line with paclitaxel or single use. It is known that RAM causes pharmacodynamic changes of plasma VEGF-A family levels during treatment. However, its clinical significance is still unclear. The aim of this study is to reveal the changes of plasma biomarker levels until disease progression, and to examine associations between plasma biomarker levels at disease progression and survival after RAM treatment failure. Methods: Plasma samples were collected at three points: base line, day 8, and disease progression. Nine kinds of plasma biomarker related to angiogenesis: VEGF-A, C, D, PlGF, sVEGFR-1, 2, Neuropilin-1 (NRP1), Angiopietin-1, and SDF-1α, were measured by means of ELISA. The dynamics of plasma biomarkers were compared using the ANOVA. Patients were dichotomized by optimal cut-off value in each biomarker. Survival after RAM treatment failure was estimated by Kaplan-Maier methods and compared by log-rank test. Results: Plasma samples were collected from 21 patients. Median age was 67 y.o and female was dominant (57%). Plasma VEGF-A and PlGF levels sharply increased at day 8 and these higher plasma levels were sustained until disease progression: the median VEGF-A and PlGF levels at baseline, day 8, and disease progression were 20.2, 350.2, and 596.7 pg/ml for VEGF-A (p<0.001) and 10.5, 223.4, and 261.1 pg/ml for PlGF (p<0.001), respectively. Conversely, plasma NRP1 levels consistently decreased during treatment course: the median NRP1 levels at baseline, day 8, and disease progression were 444.3, 309.2, and 230.9 mg/ml (p=0.001). The median survival after disease progression was 3.1 months (95%CI 2.5-3.7). Patients with higher VEGF-A and NRP1 levels showed shorter survival with 4.5 vs. 0.9 months (HR 3.15 95%CI 1.6-6.4 p<0.001) for VEGF-A and 8.8 vs. 2.6 months (HR 2.92 95% CI 1.4-6.3 p=0.002) for NRP1. Conclusions: Our data suggest that not only a clue of mechanism of acquired resistance of RAM but necessity of new treatment strategy after RAM treatment failure. Further understanding of molecular correlates and clinical validation are warranted.

Clinical significance of morphologic response and tumor shrinkage as predictive factors of Capeox+bevacizumab in 1st line treatment of metastatic colorectal cancer

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Background: Capeox + bevacizumab (BV) is one of the standard treatment for metastatic colorectal cancer (mCRC) and well known to sometimes cause morphologic response (MR). However, it is not well known the predictive value of MR in palliative chemotherapy of Capeox + BV as 1st line. The aim of this study was to investigate the clinical significance of MR and tumor shrinkage as predictive factors of Capeox+BV in 1st line treatment of mCRC. Methods: A total of 159 patients with CLM were selected from 316 mCRC patients treated with Capeox+BV as 1st line chemotherapy from February 2006 to August 2016. Among these patients, 92 patients were enrolled in the this study, who satisfied following criteria; (1) tumor responce was assesed by enhanced computed tomography (CT) images every 2-3 months, and (2) dose intensity of BV at first 4 courses were above 80%. Tumor response of RECIST1.1 and MR were evaluated by 2 radiologists. They classified them as optimal, incomplete or no morphologic response according to the morphologic criteria. Results: An optimal morphologic response (OR) was observed in 34% of all patients. The median progression-free survival (mPFS) was 9.3 months in this cohort, 13.5 months in patients with OR and 11.6 months in those with incomplete/no morphologic response. And the median overall survival (mOS) was 19.5 months, 30.3 months and 23.8 months, respectively. There were no statistical significance between OR and the other, irrespective of mPFS and mOS. On the other hand, mPFS was 14.6 months in responder as CR or PR of RECIST and 8.6 months in non responder as SD or PD (p < 0.0001). Furthermore, mOS, 31.9 months and 18.5 months, respectively (p < 0.0001). Besides in 17 patients fulfilled both responder of RECIST and OR, the mOS reached 45.4 months, which was remarkably longer compared to the other groups ( < 0.0001). Conclusions: Among mCRC patients with CLM treated with Capeox+BV as the 1st line, the response of RECIST well reflected the therapeutic effect. On the other hand, MR solely was not a predictor of therapeutic effect in this study. However, both responder of RECIST and OR may be on-treatment predictors to identify excellent prognostic group.

Serum VEGF-A and CCL5 levels as candidate biomarkers for efficacy and toxicity of regorafenib in patients with metastatic colorectal cancer

Regorafenib is an oral multi-kinase inhibitor used as salvage therapy for metastatic colorectal cancer (mCRC). We tested whether serum cytokine levels are associated with clinical outcome in the mCRC patients receiving regorafenib. Serum samples were collected before treatment start, day 21, and progressive disease, and eleven angiogenic and inflammatory cytokine serum levels were examined. Fifty-four patients of a total of 62 enrolled patients were eligible for the analyses. The chemokine ligand 5 (CCL5) levels ≤ cut-off value (59959 pg/ml) at baseline was associated with relative tumor shrinkage (P = 0.021), better progression-free survival (PFS) (P = 0.036) and overall survival (OS) (P = 0.019). Vascular endothelial growth factor A (VEGF-A) levels showing a decrease on day 21 were significantly associated with a better PFS (P = 0.021). CCL5 levels ≤ cut-off was associated with any grade hand-foot skin reaction (HFSR) (P = 0.025) and thrombocytopenia (P = 0.013). Low chemokine ligand 2 levels at baseline were associated with grade 2 ≤ HFSR. High angiopoietin-2 and basic fibroblast growth factor (bFGF) levels at baseline were associated with grade 3 ≤ total bilirubin increase and transaminases increase, respectively. Low bFGF levels at baseline were associated with grade 3 ≤ hypertension. No correlation with severe events was observed. Baseline serum CCL5 levels and decrease of the serum VEGF-A levels may serve as potential predictive markers for survival or treatment-specific toxicities in mCRC patients receiving regorafenib.

Clinical significance of BRAF non-V600E mutations on the therapeutic effects of anti-EGFR monoclonal antibody treatment in patients with pretreated metastatic colorectal cancer: the Biomarker Research for anti-EGFR monoclonal Antibodies by Comprehensive Cancer genomics (BREAC) study

Background:

Patients with BRAF^V600E-mutated metastatic colorectal cancer (mCRC) have a poorer prognosis as well as resistance to anti-EGFR antibodies. However, it is unclear whether BRAF mutations other than BRAF^V600E (BRAF^non-V600E mutations) contribute to anti-EGFR antibody resistance.

Methods:

This study was composed of exploratory and inference cohorts. Candidate biomarkers identified by whole exome sequencing from super-responders and nonresponders in the exploratory cohort were validated by targeted resequencing for patients who received anti-EGFR antibody in the inference cohort.

Results:

In the exploratory cohort, 31 candidate biomarkers, including KRAS/NRAS/BRAF mutations, were identified. Targeted resequencing of 150 patients in the inference cohort revealed 40 patients with RAS (26.7%), 9 patients with BRAF^V600E (6.0%), and 7 patients with BRAF^non-V600E mutations (4.7%), respectively. The response rates in RAS, BRAF^V600E, and BRAF^non-V600E were lower than those in RAS/BRAF wild-type (2.5%, 0%, and 0% vs 31.9%). The median PFS in BRAF^non-V600E mutations was 2.4 months, similar to that in RAS or BRAF^V600E mutations (2.1 and 1.6 months) but significantly worse than that in wild-type RAS/BRAF (5.9 months).

Conclusions:

Although BRAF^non-V600E mutations identified were a rare and unestablished molecular subtype, certain BRAF^non-V600E mutations might contribute to a lesser benefit of anti-EGFR monoclonal antibody treatment.

Abstract 2712: Relationship between CLDN18-ARHGAP fusion gene and clinicopathological features of gastric cancer in young adult

Introduction: Gastric cancer (GC) in young adults comprises a small part of this disease population having the distinctive clinicopathological features, such as diffusive tumor growth and peritoneal dissemination. Genetic alterations underlying these features and the development of cancer in early ages remain unclear. Comprehensive molecular analyses by TCGA have suggested 4 molecular subtyping of GC and revealed enrichment of CLDN18-ARHGAP fusion gene in Genomically stable (GS) type which mainly included diffuse type. In this study, we examined the relationship between CLDN18-ARHGAP and clinicopathological features of GC affecting young adults.

Method: Patients (pts) diagnosed at the age younger than 40 years-old were defined as the GC in young adults, and underwent surgery at our institute between Jan 2006 and Dec 2015 were enrolled to this study. Tissue microarrays were prepared from formalin-fixed and paraffin-embedded surgical specimen. DNA probes for CLDN18, ARHGAP-26 and -6 were created using bacterial artificial chromosomes and fusion genes were detected by a FISH method.

Results: Out of 155 surgical specimens available for analysis, we found CLDN18-ARHGAP fusion gene in 21 pts (13.5%). Among these, 19 cases were CLDN18-ARHGAP26 fusion and the others were CLDN18-ARHGAP6. Cancers with CLDN18-ARHGAP fusion genes were all diagnosed as diffuse type and included more large-sized, multiple lymph node metastases and advanced stages tumors (table 1). The proportion of detected fusion genes in this study was almost equivalent to that of GS type in TCGA cohort. Analysis of variations of breakpoint is planned to confirm by RT-PCR and sequencing. Additionally, we are going to study the association of CLDN18-ARHGAP with RHOA or CDH-1.

Conclusion: CLDN18-ARHGAP fusion gene might account for the characteristic of a part of diffuse type GC. Further comprehensive molecular analysis comparing to general GC population is warranted.

Patient demographicspositive (n=21)negative (n=134)p-valueAge0.646&lt;30 / 30-392 / 199 / 125Sex0.482man / woman8 / 1365 / 69Tumor location0.507Upper /Middle /Lower4 / 10 / 743/ 53 / 38Tumor size (mm)75.664.70.117≤80 / 80&lt;9 / 1234 / 100Borrmann0.648Type2 / 3 / 4 / others0 / 8 / 3 / 1010 / 38 / 20 / 62LaurenNSintestinal / diffuse / mixed0 / 21 / 05 / 124 / 5T (TNM)0.479T1 / T2 / T3 / T46 / 1 / 4 / 1050 / 18 / 18 / 48N (TNM)0.044N1 / N2 / N36 / 2 / 2 / 1171 / 12 / 20 / 31Stage (TNM)0.032I / 2 / 3 / 47 / 1 / 5 / 857 / 28 / 31 / 18

Citation Format: Izuma Nakayama, Eiji Shinozaki, Seiji Sakata, Noriko Yamamoto, Satoko Baba, Kensei Yamaguchi, Shunji Takahashi, Kengo Takeuchi, Tetsuo Noda. Relationship between CLDN18-ARHGAP fusion gene and clinicopathological features of gastric cancer in young adult [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2712. doi:10.1158/1538-7445.AM2017-2712

Change in clinical outcomes during the transition of adjuvant chemotherapy for stage III colorectal cancer

Background

There are robust data supporting the contribution of oxaliplatin (L-OHP) regarding clinical outcomes for colorectal cancer (CRC) in an adjuvant setting in European and US trials; however, there is no Japanese clinical evidence although L-OHP has been approved since 2009. We examined the transition of adjuvant chemotherapy for stage III colorectal cancer in our institute.

Methods

A total of 642 patients with histopathologically confirmed stage III CRC underwent curative surgery from 2005 to 2010. We examined disease free survival (DFS), overall survival (OS) and prognostic factors for stage III CRC patients who underwent adjuvant chemotherapy.

Results

A total of 509 patients received adjuvant chemotherapy. 3-year DFS and 5-year OS rates were 74.5% and 87.5%, respectively. The frequency of inclusion of L-OHP as adjuvant chemotherapy was increased after 2008. A total of 189 patients received adjuvant chemotherapy from 2005 to 2007 increasing to 320 patients from 2008 to 2010; the 5-year OS rates were 82.4% and 91.5%, respectively, and the 3-year DFS rates were 69.2% and 76.6%, respectively (OS, P = 0.007; DFS, P = 0.023). In univariate analysis, adjuvant chemotherapy including L-OHP was no significant deference compared to FU monotherapy. (OS: HR 0.88, 95%CI 0.4–1.91, p = 0.75, DFS: HR 0.78, 95%CI 0.21–2.3, p = 0.29). In multivariate analysis, the OS was predicted by means of N stage (HR = 2; 95%CI, 1.1–3.8; P = 0.02) and pathology (HR = 0.28; 95%CI, 0.13–0.59; P = 0.0008). The DFS was predicted by means of N stage (HR = 2.67; 95%CI, 1.82–3.9; P < 0.05), T stage (HR = 1.61; 95%CI, 1.1–2.3; P = 0.01) pathology (HR = 0.47; 95%CI, 0.29–0.75; P < 0.05) and venous invasion (HR = 2.06; 95%CI, 1.12–3.77; P = 0.01).

Conclusions

Clinical outcomes of stage III CRC patients receiving adjuvant chemotherapy improved. The frequency of L-OHP usage was increasing annually, however it was no influence for clinical outcomes in this study. It will be necessary to reevaluate additional effect of L-OHP with more patients.

Multicenter phase I/II trial of BBI608 and pembrolizumab combination in patients with metastatic colorectal cancer (SCOOP Study): EPOC1503

TPS3623

Background: Immune checkpoint inhibitor (ICI) was reported to show durable responses in patients with MSI-H (Microsatellite Instability-High) metastatic colorectal cancer (mCRC). On the other hand, for patients with MSS (Microsatellite Stable) mCRC, ICI monotherapy achieved no response. Recently, WNT/β-catenin signaling has been reported to be involved in the elimination of tumor-infiltrating lymphocytes and the resistance of anti-PD-L1 antibodies. CRC is representative cancer with WNT/β-catenin pathway activation. Furthermore, STAT3 has also been reported to be a key driver of this immune evasion. Considering these rationales, the blocking of these signaling pathways with ICI may enhance antitumor immune response. Therefore, we initiated phase I/II study to assess efficacy and safety for the combination of BBI608, which blocks STAT3 and WNT/β-catenin signaling, with pembrolizumab in patients with mCRC. Methods: The eligibility criteria were patients with gastrointestinal cancer not responded to or intolerant of standard chemotherapies (SOC) for phase I part, and MSS mCRC refractory or intolerant to fluoropyrimidine, irinotecan, oxaliplatin, and anti-EGFR antibody (if wild-type RAS) for Cohort B in phase II part. For Cohort A, MSI-H mCRC refractory or intolerant to the SOC, irrespective of anti-EGFR antibody are investigated. Phase I part was designed to determine the recommended phase II dose in a “3+3” cohort-based dose escalation design of BBI608 (240mg BID every day on level 1 and 480mg BID every day on level 2) with pembrolizumab (200mg/body q3w). Primary endpoint of the phase II part is Immune-related objective response rate (irORR) determined by their Response Evaluation Criteria In Solid Tumors (irRECIST). A null hypothesis and alternative hypothesis for cohort B are irORR = 5% and 20%, respectively. Required sample size for Cohort B was 40 with a one-sided alpha of 5% and power of 90%. Required sample size for Cohort A (10 patients) was determined in an exploratory manner. We also investigate biomarker study using paired samples of both tumor biopsy and blood. The enrollment to phase I part began in November 2016. Clinical trial information: NCT02851004. Clinical trial information: NCT02851004.

A phase II study of panitumumab with FOLFOX or FOLFIRI as first-line chemotherapy for KRAS-wild type metastatic colorectal cancer: The PaFF-J study

722

Background: For the patients with unresectable metastatic colorectal cancer (mCRC), response to the1st line chemotherapy has strong impact on their prognosis. Shrinkage of tumors may result in conversion to surgical resection and, concurrently, improved their survival. We conducted a multicenter phase II trial to investigate the efficacy and safety of panitumumab (Pmab) with chemotherapy as the 1st line treatment in Japanese patients with mCRC. Methods: Patients with no prior chemotherapy for unresectable, KRAS wild type mCRC, 20-80 years, and PS 0-1 were arbitrarily received either FOLFOX + Pmab or FOLFIRI + Pmab. Patients were evaluated every 8 weeks until progression. The primary endpoint was overall response rate (ORR), the secondary endpoints were progression-free survival (PFS), overall survival (OS), disease control rate (DCR), R0 resection rate, and safety. Results: A total of 162 patients (140 with FOLFOX + Pmab and 22 with FOLFIRI + Pmab) were analyzed. Median follow-up was 28.2 months, median age at enrollment was 64.5 years, and 17.9% of the patients was recurrent disease. Number of target organ was 1 in 35.2%, 2 in 40.7%, and ≥ 3 in 24.1% of the subjects. Median administered cycle was 7, and median treatment duration was 16 weeks. ORR was 51.2% (95%CI: 43.3-59.2), and DCR was 82.1% (95%CI: 75.3-87.7). ≥ 30% tumor shrinkage (PR-in) was observed in 115 patients (71.0%). Median time to PR-in and maximum shrinkage was 10 and 16 weeks, respectively. Surgical resection was done in 66 patients (40.7%), of which R0 was in 43 patients; R0 resection rate was 26.5% (95%CI: 19.9-34.0). Median PFS and OS was 9.2 (95%CI: 7.2-11.4) and 33.8 months (95%CI: 29.4-43.1), respectively. ≥ Grade 3 adverse events with > 5% incidence were neutropenia (31.8%), stomatitis (10.5%), rash acneiform (9.9%), paronychia (9.3%), anorexia (8.6%), and diarrhea (6.2%). Conclusions: In our study, OS was favorable with high R0 resection rate, whereas ORR, DCR, PFS and toxicities were similar to those in previously reported studies. Because the maximum tumor shrinkage was observed around 16 weeks, optimal timing for considering conversion surgery might be 16 weeks from the start of treatment. Clinical trial information: UMIN000004991.

Effect of thymidine kinase 1 expression on prognosis and treatment outcomes in refractory metastatic colorectal cancer: Results from two randomized studies of TAS-102 versus a placebo

529

Background: TAS-102 is an oral nucleoside antitumor agent, comprising trifluridine (FTD) and tipiracil. FTD is incorporated into DNA after phosphorylation by thymidine kinase 1 (TK1). This study aimed to investigate the association between TK1 expression and TAS-102 efficacy in refractory metastatic colorectal cancer (mCRC) patients (pts). Methods: Data from two randomized phase 2 and phase 3 studies of mCRC pts refractory to standard therapies were analyzed for treatment outcomes in relation to TK1 expression. Expression was measured using immunohistochemistry, and staining was classified according to intensity and scored 0, 1+, 2+, or 3+. Occupancy rates of the areas scored 2+ and 3+ in tumor cells were calculated in 5% intervals, and divided into two groups (high or low TK1) at each cut-off point. Results: TK1 expression was evaluated in 329 pts. Baseline characteristics and treatment outcomes were comparable between the TK1-refined and intention-to-treat populations. Pts with high TK1 expression who received the placebo had a poor prognosis, while those receiving TAS-102 showed a significant improvement in overall survival (OS) at cut-off points of 5% to 15%, and 30%. Conclusions: High TK1 expression could be a poor prognostic factor and a predictive factor of TAS-102 efficacy in mCRC pts. [Table: see text]

Prognostic factors of trastuzumab-based chemotherapy in patients with advanced HER2 positive gastric cancer

41

Background: Prognostic factor in patients with HER2 positive gastric cancer who received trastuzumab (T-mab) based chemotherapy remains unclear. The aim of this study is to reveal the clinical factors which predict prognosis in T-mab based chemotherapy. Methods: We retrospectively reviewed HER2 positive gastric cancer patients treated with T-mab based chemotherapy in our institute from March 2011 to June 2016. Patients’ demographics according to the ToGA study and laboratory data were examined. Results: Total of 143 patients were enrolled. Median follow-up period was 14.9 months, and median progression-free survival (PFS) and overall survival (OS) were 11.2 months (95% CI: 8.6-13.9) and 20.9 months (95% CI: 16.6-25.2), respectively. In univariate analysis, performance status (0 vs. 1-2), present of measurable lesion, presence of visceral metastases, No. of metastatic lesion (1-4 vs. > 4), LDH, ALP, Alb, median CEA (≧ 13.6 mg/ml vs. < 13.6mg/ml), and median Neutrophil/Lymphocyte (N/L) ratio (≧ 3.11 vs. < 3.11) were significantly associated with PFS. Regarding OS, extension of disease (locally advanced vs. metastatic), presence of visceral metastases, No. of metastatic lesions, Hb, ALP, Alb, CRP, median CEA and median N/L ratio were significant. In multivariate analysis, CEA levels (HR 0.54: 95%CI 0.34-0.86, p = 0.010) and ALP (HR 0.57: 95%CI 0.33-0.99, p = 0.046) retained to be significant in regard to PFS. Patients with < median CEA level had a median PFS of 13.1 months vs. 7.2 months with ≧ median CEA level. Patients with normal level of ALP showed a median PFS of 12.8 months vs. 5.9 months with abnormal ALP level. With respect to OS, CEA levels (HR 0.59: 95%CI 0.34-1.03, p = 0.061) and N/L ratio (HR 0.55: 95%CI 0.29-1.06, p = 0.074) were marginally significant. Patients with < median CEA level had a median OS of 27.6 months vs. 17.6 months with ≧ median CEA level. Patients with > median N/L had a median OS of 24.5 months vs. 16.5 month with ≧ median N/L. Conclusions: Lower CEA levels and normal ALP levels were associated with favorable PFS, and lower CEA and N/L ratio were marginally associated with favorable OS.