63P Molecular markers as predictors of response to perioperative FLOT chemotherapy in gastric cancer

Perioperative FLOT chemotherapy has improved the prognosis in patients with locally advanced resectable gastric cancer (GC). However, 80% of cases, tumor is resistant to therapy, and are exposed unnecessary toxicity delayed surgical treatment. The aim this study was identify molecular predictive markers efficacy perioperative GC. retrospective included 185 patients. All samples were assessed for HER2 microsatellite instability (MSI) status. Among all cases there 45 T2-4N1-2 M0 GC, who underwent a total or subtotal gastrectomy D2 lymphadenectomy FLOT. MSI detection performed using mononucleotide (NR21, NR24, NR27, BAT25, BAT26) by fragment analysis. gene amplification testing fluorescent situ hybridization. Also 19 tested copy number changes FGFR1, FGFR2, KRAS, MET, EGFR, CCND1, MYC genes multiplex-ligation probe endpoints progression-free survival (PFS) objective response rate (ORR). detected 4.8% (9/185) GC cases. Prevalence 7.5% (14/185). PFS HER2-positive receiving (4/45), significantly lower than HER2-negative GC: median 156 317 days, respectively (p=0.0006). There no correlation between alteration (OR) (p=1.0). KRAS (3/19) comparing without amplification: 98 327 (p<0.0001). association an increase ORR For other studied statistically significant found (p>0.05). presence have been shown as promising treatment failure treated