e20666 Background: Currently regimen for advanced non-small cell lung cancer (NSCLC) failing from standard treatment is deficient. This retrospective study aimed to assess the efficacy and safety of low-dose apatinib in combination with S-1 therapy in this NSCLC setting. Methods: In this retrospective study, advanced NSCLC patients who failed from standard treatment in Changzhou Cancer Hospital of Soochow University were screened for eligibility. Progression-free survival (PFS) was set as the primary endpoint. Overall response rate (ORR), disease control rate (DCR), Overall survival (OS) and safety profile were considered to be the secondary endpoints. Results: 31 eligible patients were included in this study. The median PFS (mPFS) was 102 days (95% CI: 57-147). 7 patients (23%; 95% CI: 11-38%) achieved an objective response and the DCR was maintained in 23 patients (75%; 95% CI: 58-86%). The median OS (mOS) was 422 days (95% CI: 148-696).Patients with smoking had a tendency for shorter overall survival without significant differences (HR = 4.105, 95% CI: 0.874-19.288, P = 0.074). Treatment-related grade 3 toxicity was observed in five patients (16%) and the common grade 1 or 2 adverse events were fatigue (42%), hypertension (32%), and hand-foot-skin reaction (23%). Conclusions: Combination of low-dose apatinib and S-1 could be effective and tolerable for advanced NSCLC patients failed from standard treatment, but further exploration in larger clinical trials is needed.

e20519 Background: The frequency of EGFR mutation in Asian advanced lung cancer patients is about 40% and the application of EGFR tyrosine kinase inhibitors (TKIs) has become a standard treatment therapy. Several studies showed that usage of EGFR TKIs in adjuvant or neo-adjuvant therapy was promising, while the mutation profile of EGFR mutations in resectable Chinese lung cancer patients was still scanty. Our study investigated EGFR mutation profile and its correlation with clinicopathological factors. Methods: 343 resectable patients with lung cancer were selected for eligibility criteria, and tumor tissues were collected for gene detection. EGFR genetic testing was performed by amplification refractory mutation system PCR (ARMS-PCR) with specific sensitive mutation sites. The clinicopathological factors of study population were recorded based on pre-design protocol. Chi-square or fish exact test were used to statistic analysis Results: A total of 343 patients were enrolled in study. 42.6% (146/343) patients were male, 20.4% (68/333) patients were smokers, the adenocarcinoma accounted for 93.8 % (319/340), and stage 0, I, II, III was 7.3% (25/343), 68.8% (236/343), 8.5% (29/343), 15.5% (53/343), respectively. The frequency of EGFR mutation was 54.2% (186/343) in whole population, and the proportion of EGFR L858R, 19Del, 719X, 768I, 861Q mutation was 31.2% (107/343), 21.3% (73/343), 1.2% (4/343), 1.0% (3/343), 1.0% (3/343), respectively. 1.2% (4/343) patients presented EGFR co-mutation (EGFR G719X/S768I; L858R/S768I; G719X/S768I; L858R/L861Q) .The mutation frequency of EGFR mutation was associated with sex, smoking, differentiation, pathology (P = 0.0076, < 0.0001, < 0.0001, < 0.0001, respectively). In subgroup analysis, the incidence of two main mutation types, EGFR L858R and 19del, were associated with disease stage (P = 0.044) and age (P = 0.035). Conclusions: EGFR mutation in resectable lung cancer was a common phenomenon as advanced stage and our study might provide useful informations for using EGFR-TKIs in further adjuvant or neo-adjuvant therapy.

e15511 Background: Clinical outcomes of adjuvant chemotherapy in gastric cancer (GC) have considerable stage-independent variability, which underscores the need for predictive molecular markers. Previous studies indicated that CHAF1A played a critical role in tumor growth, but whether it was associated with adjuvant chemotherapy in GC was still unknown. This retrospective study investigated the prognostic value of CHAF1A in adjuvant chemotherapy of GC. Methods: A total of 325 stage IB-III patients with fluoropyrimidines (FU)-based adjuvant chemotherapy after curative D2 gastrectomy meeting eligibility criteria were selected. CHAF1A protein expression was determined by immunohistochemical method. The primary outcomes were Overall survival (OS) and Disease-free survival (DFS). Kaplan-Meier method was used to estimate survival curve and Cox model for multifactor analysis. Results: CHAF1A mRNA was overexpressed in GC tissues and positive CHAF1A protein expression was not associated with OS and DFS in overall patients treated by FU-based chemotherapy ( P = 0.391 and 0.511, respectively). However, as stratified by tumor sites, positive CHAF1A expression was associated with poor OS and DFS in non-cardia cancer ( P = 0.009 and 0.007, respectively) but not in cardia cancer ( P = 0.229 and 0.112, respectively). Multivariate analysis indicated that CHAF1A expression level was still an independent predictor for both OS (HR = 2.42; 95% CI: 1.12-5.20; P = 0.024) and DFS (HR = 1.91; 95% CI: 1.03-3.54; P = 0.039) in non-cardia GC. Furthermore, CHAF1A was correlated with the status of microsatellite instability ( P = 0.025). Conclusions: CHAF1A might be a predictor for outcomes of FU-based adjuvant chemotherapy in patients with non-cardia GC, but needed further prospective studies to confirm.

3024 Background: The dosage of most chemotherapy drugs were performed based on the patients’ body surface area (BSA), including docetaxel (DTX). Previous studies showed that this conventional administration of DTX might cause adverse event, such as neutropenia, and neutropenia was proved to associate with DTX area under curve (AUC). This study was designed to evaluate the effect of dose-administration of DTX based on dynamic detection of DTX AUC on clinical outcomes. Methods: A total of 209 patients with DTX chemotherapy (one cycle every 3 weeks) were enrolled, and all patients received 2-6 cycles of treatment. In the first cycle, dosage of DTX based on BSA was administrated in all study population. From the second cycle, one group patients (control group) received DTX according to traditional BSA and the other group patients (experimental group) on the basis of dynamic detection of DTX AUC. The primary outcome was incidence rate of neutropenia and the second outcome was disease control rate (DCR). Results: Patients with grade 3 or higher neutropenia from the fourth to sixth cycle of DTX chemotherapy were significantly lower in the experimental group compared with the control group (P= 0.039, 0.012, and 0.001, respectively). In the experimental group, compared with the first cycle, and the number of patients falling within the therapeutic window increased by 27.19% in the sixth cycle after dose adjustment according to the AUC value of previous cycle. The DCR in the experimental and control group is 85.32% and 72.00%, respectively (P= 0.018). Conclusions: The administration method based on dynamic detection of AUC of DTX could significantly reduce incidence rate of neutropenia and received a higher DCR, but the result needed to be confirmed in further studies.

e15512 Background: Programmed death ligand 1 (PD-L1) expression has become a promising biomarker in predicting the efficacy of immune checkpoint inhibitors in various advanced cancers, including gastric cancer (GC). However, the prognostic value and clinicopathological significance of PD-L1 in GC is still not clearly identified. Hence, we carried out a meta-analysis to investigate the potential role of PD-L1 in GC, expecting to provide new clues for the judgement of prognosis in resected gastric cancer. Methods: A literature search strategy was performed from the PubMed, Web of Science, EMBASE, and the Cochrane Library database as of December 1, 2018. Relevant data was rigorously extracted from the included literatures. Hazard ratios (HRs) and Odds ratios (ORs) along with 95% confidence intervals (95% CIs) were used to evaluate the prognostic value or clinicopathological significance of PD-L1 expression in GC. Results: A total of 21 studies containing 6021 patients fitted into our meta-analysis. The pooled HRs indicated that PD-L1 high-expression accompanied with a worse overall survival (OS) (HR=1.28, 95% CI: 1.01-1.62, P=0.04) in GC, while no correlation with disease-free survival (DFS) (HR=0.88, 95%CI: 0.53-1.45, P=0.61). Subgroup analysis showed that PD-L1 high-expression was negatively associated with distant metastasis groups (OR=0.66, 95%CI:0.48-0.89, P=0.01), but was positively related to elderly(OR=1.19, 95%CI: 1.01-1.40, P=0.04), lymph-node metastasis(OR=1.63, 95%CI: 1.08-2.46, P=0.02), deeper tumor infiltration(OR=1.73, 95%CI: 1.08-2.79, P=0.02), Epstein-Barr virus infection positive (EBV+) (OR=8.01, 95%CI: 3.10-20.72, P<0.0001), and MET positive (MET+) groups (OR=1.78, 95%CI: 1.05-3.00, P=0.03). Conclusions: Our meta-analysis found that the high-expression of PD-L1 accompanied with a poor OS. Moreover, PD-L1 high-expression was related to age, lymph-node metastasis, depth of infiltration, distant metastasis, EBV infection, and MET status.