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e21504 Background: The immune checkpoint inhibitors (ICIs), have improved survival with durable response for advanced malignant melanomas, but, only a minority of patients has achieved. To stay sway failure of triage patients, considerable side effects and costs of ICB therapies, the development of robust signatures predictive of response to ICB therapies is warranted. Methods: Clinical data were collected at Seoul St. Mary’s Hospitals. Among them, we examined RNA expression profile by QuantSeq 3’ mRNA-Sequencing and the composition, and spatial distance of immune cells by multiplex immunofluorescent staining. Results: The gene sets with relatively higher RNA expression in the good response group, were as follows; hematopoietic cell dedifferentiation gene, T-cell related adaptive immunity gene, IFN-related cytokine gene, and macrophage (TAM), NK cell, innate immunity gene set. Meanwhile, in the poor response group, inflammatory response, fibrosis response genes was increased.The cell densities of T cells, cytotoxic T cells, Treg cells, CD8+Treg cells, and exhausted T cells in the good response group tended to be higher, which was clearer in the peritumoral (PT) area than the intratumoral (IT) area. For the good response group, M1/M2 ratio in the IT area was significantly higher compared to that of poor response group (p = 0.045). According to the nearest neighbor analysis for % of melanoma cells within 15um distance present a close distance from M1, M2, and NK cells tended to be higher in the IT area than PT area. For the cases with higher spatial distribution from M1 in the IT area, PFS and OS was significantly extended (PFS, p = 0.0021; OS, p = 0.036). The gene sets with relatively higher mRNA expression in high neighborhood macrophage group, were cell death, apoptosis process gene set. In low neighboring M1 macrophage group, relatively higher mRNA expressions of extracellular component inflammation and fibrosis gene, cell migration, and cell de-differentiation gene set were observed. Conclusions: Taken together, our results suggest 4 key points. First, good and poor responder groups for ICB show marked differences from mRNA profiling to protein expression according to central dogma. Second, immune cells can be distributed sporadically in many places, but the actionable ground of the adaptive immune cells of the T cell family is the PT, and the playground of innate immune cells such as TAM and NK cells is the IT. In particular, the anti-tumor response of M1 macrophage and M2 macrophage was oppositely in IT. Third, high TAMs in IT are interpreted to have a tumoricidal effect because they show a stationery state while coding the killing effect gene set. In addition, topologically, spatial analysis as well as bulk genomics are important for predicting tumor response for ICIs.

e12528 Background: The treatment of male breast cancer (MBC) has been extrapolated from female breast cancer (FBC) because of its rarity despite their different clinicopathologic characteristics. We aimed to investigate the distribution of intrinsic subtypes based on immunohistochemistry (IHC), their clinical impact, and treatment pattern in clinical practice through a multicenter study in Korea. Methods: We retrospectively analyzed clinical data of 248 MBC patients 18 institutions across the country from January 1995 to July 2016. Results: The median age of MBC patients was 63 years (range: 25–102 years). Among the 148 patients that underwent intrinsic subtype classification, 61 (41.2%), 44 (29.7%), 29 (19.5%), and 14 (9.5%) were luminal A, luminal B, HER2, and triple-negative breast cancer (TNBC), respectively. TNBC patients showed inferior survival compared with those with other subtypes. Of the 221 patients with operable breast cancer, 108 (48.6%) received adjuvant chemotherapy and 52 (23.5%) received adjuvant radiation therapy. Most hormone receptor-positive patients (166 patients, 82.6%) received adjuvant endocrine treatment. Five-year completion of adjuvant endocrine treatment was associated with superior disease-free survival (DFS) in patients classified with an intrinsic subtype (hazard ratio [HR] = 0.19, 95% confidence interval [CI] 0.005–0.65, P = 0.008) and in all patients (HR = 0.16, 95% CI 0.05–0.54, P = 0.003). Conclusions: Distribution of subtypes of MBC was similar to FBC and luminal type A was most common. Overall survival tended to be improved for luminal A subtype although there was no statistical significance. Completion of adjuvant endocrine treatment was associated with prolonged DFS in intrinsic subtype classified patients. MBC patients have tended to receive les treatment. MBC patients should be treated with standard guideline as FBC patients receive.

e17062 Background: Clear cell ovarian cancer is rare, accounts for about 3-10% of epithelial ovarian carcinoma, and is known to be associated with endometriosis. This tumor type has poor prognosis due to inherent chemoresistance. We investigated clinical characteristics and prognostic factors of clear cell ovarian cancer in South Korea. Methods: We reviewed the medical records of 308 patients with clear cell histology ovarian cancer who underwent debulking surgery from 21 institutions in South Korea between 1995 and 2015. Results: Mean age was 51 years (range, 25-81) and 194 patients (63.7%) had stage I disease, 34 (11.1%) had stage II, 66 (21.6%) had stage III, and 11 (3.6%) had stage IV. 107 patients (34.9%) had endometriosis. 9 patients (2.9%) received neoadjuvant chemotherapy, 248 (80.5%) received postoperative chemotherapy, and among them, 238 (96%) received taxane-platinum chemotherapy. 275 patients (89.3%) achieved optimal debulking. 112 patients (37%) had recurrence, 182 (59.1%) was disease-free, and 12 (3.9%) lost follow up. Median value of CA-125 was 72.34 U/ml (range, 1.9-8930), 45.7 in stage I, 98.9 in stage II, 192.1 in stage III, and 634.8 in stage IV. 1-year, and 3-year rate of disease-free survival (DFS) was 70%, and 63%, respectively. 1-yr DFS rate was 90% in stage Ia and Ib, 88% in stage Ic and II, and 60% in stage III and IV. According to the same stage grouping, 3-year DFS rate was 82%, 70%, and 40%, respectively. Overall survival (OS) rate at 1 year was 97%, 99%, and 90%, and 97%, 96%, and 88% at 3 year. Multivariate analysis revealed optimal debulking (HR 6.62, p < 0.001) as a significant prognostic factor for DFS. Among the 94 patients with early stage (Ia and Ib), 17 patients (18.1%) received adjuvant chemotherapy, and there was no significant difference in DFS according to adjuvant chemotherapy (log rank p = 0.57). Conclusions: In patients with clear cell ovarian cancer, optimal debulking surgery was associated with improved DFS. And the role of adjuvant chemotherapy in early stage clear cell ovarian cancer is elusive and needs further study.

344 Background: Nal-IRI plus 5-FU/LV has demonstrated efficacy in mPDAC pts who previously received gemcitabine-based therapy in the pivotal NAPOLI-1 trial. Real-world data are helpful to measure the clinical outcomes and safety profile of this regimen in daily practice setting. Methods: Between January 2017 and April 2018, a Named Patient Program (NPP) was activated to provide controlled, pre-approval access of nal-IRI in Korea. This analysis is multicenter retrospective study for patients who received nal-IRI plus 5-FU/LV under the NPP. Results: A total of 86 patients entered into this NPP among 10 Korean institutions. Median age was 61 years (range, 37-79) and 52 pts (60%) were male. Liver (n=49, 57%), peritoneum (30, 35%), and lung (27, n=31%) were the most common metastatic sites. All patients had ECOG performance status 0-1 and previously received gemcitabine-based therapy. Prior to nal-IRI plus 5-FU/LV, 35 (41%) and 51 (59%) patients received

8578Background: Thymic epithelial tumors (TET) are consisted of thymoma(TM) and thymic carcinoma(TC). They are rare heterogeneous tumors with a broad spectrum of clinical characteristics. Although ...

486 Background: There is no estabilished consensus about chemoradiation therapy for resected cholangiocarcinoma, and many studies are ongoing. We tried to cofirm the effectiveness and side effects of chemoradiation after operation of cholangiocarcinoma and find the prognostic factors. Methods: We found the patients with cholangiocarcinoma who receieved chemoradiation after surgery between 2002 and 2015 from two hospitals in South Korea. We checked the baseline chareacteristics, efficacy and toxicities. And we tried to identify the prognostic factors for recurrence by statistical anaylsis. Results: We retrospectivally studied 51 cholangiocarcinoma patients. Median age was 64 (range 48-83), and Men was 30 patients (58.8%) of them. By location, there were 10 (19,6%) intrahepatic cholangiocarcinomas, 13 (25.5%) hilar cholangiocarcinoma, and 28 (54.9%) extrahepatic cholangiocarcinomas. All patient received 5-FU chemoradiation after surgery. R0 resections were 31 (60.8%), R1 resections were 20 (39.2%) There was recurrence with 35 (68.6%) patients. Median relapse free survival was 292 (range 86-1769) days. Locoregional recurrence were 16 (31.4%), and distant recurrences were 26 (51.0%). For hematological toxicity, the patients showed grade 3 toxicities, as leukopenia 5 (9.8%), anemia 1 (2.0%) , thrombocytopenia 1 (2.0%). For non-hematological toxicities, there were G3 toxicities as Infection 2 (4.0%), nausea/vomiting 1 (2.0%), Adhesive ileus 1 (2.0%), bleeding 1 (2.0%). For multivariate analysis, Tumor site (HR 1.88 (95% CI 1.09-3.23). P = 0.022) and modality of radiation therapy (HR 13.27 (95% CI, 3.56-49.50)), P < 0.001) were statistically meaningful factors. Conclusions: Although this is a retrospective study, we found that the result of chemoradiation therapy for some patients showed good efficacy and tolerable toxicity. We could consider chemoradiation for adjuvant therapy in cholangiocarcinoma, especially for extrahepatic cholangiocarcinoma. And intensity-modulated radiation therapy should be performed than three-dimensional radiation therapy in cholangiocarcinoma.

e14558 Background: Although many clinical trials of newly developed chemotherapeutic drugs have been conducted, limited studies have focused on gastric cancer patients specifically diagnosed with peritoneal carcinomatosis (PC) without measurable regions. In the current study, we characterized the outcomes of systemic chemotherapy and prognostic factors for patients with gastric cancer PC, particularly in cases without measurable disease. Methods: Clinical data from 211 gastric cancer PC patients (137 without and 74 with measurable disease) subjected to systemic chemotherapy between January 2000 and December 2010 at a single center were reviewed. Results: Median OS rates of gastric cancer PC patients with no measurable disease were significantly longer than those of patients with measurable disease (18.2 vs 12.0 months, p=0.011). In multivariate analysis, poor PS (Hazard ratio (HR) = 2.33, 95% CI, 1.42-3.8, P=0.001), presence of metastatic lymphadenopathy (LAP) (HR=2.23, 95% CI, 1.42-3.5, p=0.002) and high-grade PC (HR=1.82, 95% CI, 1.09-3.04, p=0.025) were associated with significantly decreased OS. Combined with clinical PC grade and measurability of disease, median OS of patients with low-grade PC without measurable disease was 19.6 months (95% CI, 15.5-23.7 months). Median OS rates of 12.6, 13.7 and 6.8 months were estimated in high-grade PC without measurable disease, low-grade PC with measurable disease, and high-grade PC with measurable disease, respectively. Median OS of low-grade PC patients with no measurable disease was significantly higher than that of patients in all other groups (p=0.001, p=0.029 and p

e19614 Background: There are some known risk factors for deep vein thrombosis in cancer patients, such as primary site of cancer, white blood cell count (WBC), hemoglobin (Hb), platelet count (PLT). We investigated the association between these factors and the overall survival as prognostic factor in gastrointestinal (GI) cancer patients. Methods: All the patients with gastrointestinal cancer, who developed deep vein thrombosis or pulmonary thromboembolism through the clinical course, were retrospectively reviewed between January 2009 and June 2011 at Seoul St. Mary’s Hospital. According to treatment, patients were classified into two groups; the chemotherapy group and the supportive care group. Results: Of the fifty-six patients, median age was sixty three year-old. Stomach cancer was most common 35% , pancreatic cancer 31%, colorectal cancer 19%, and biliary cancer was 15%. There were three pattern of thrombosis: 19 (34%) deep vein thrombosis (DVT) only, 12 (21%) pulmonary thromboembolism (PTE) only, 25 (45%) combined DVT with PTE. WBC count above 11,000/µ° showed the poor overall survival than other group (median survival 3.4 months vs. 1.7 months, respectively, p=0.015) However, other risk factor did not show any significant association (Hb: p=0.521, PLT: p=0.295) In chemotherapy group, twelve (55%) patients had progressive disease and ten (45%) patients had stable disease at the time of thrombotic event. There was no statistically significant association between thrombosis and tumor response. The chemotherapy group had tendency of better survival outcome than the supportive care group without statistical significance (median survival 2.4 months vs. 5.3months, p=0.07). Conclusions: In GI cancer patients, elevated white blood cell count above 11,000/µ° can be important prognostic and risk factor for thrombosis with poor survival outcome. And the response of chemotherapy seemed to have no influence on thrombotic event during chemotherapy. This is very limited study due to small sample size and retrospective analysis, and heterogenous type of cancer. Further large study should be warranted to define the thrombotic risk factor as prognostic marker.