Abstract 4586: FGFR2 amplification in serous ovarian cancer

Abstract Fibroblast growth factor receptor (FGFR) signaling pathway plays an important role in biology of cancer. Approximately 7% of ovarian cancer (OC) exhibits FGFR1 amplification. Recently the overexpression of FGFR2 was found in 95% of clear cell OC. Up to date there is no data about FGFR2 status in OC. 54 paraffin-embedded blocks from 18 patients with serous OC were analyzed by FISH to identify FGFR2 amplification. Scoring for amplification and polysomy level was adopted from previous studies for gastric cancer (Su X, et al. BJC 2014). Material from each patient had 3 samples: from primary tumor, from primary metastatic lesions, and from relapse. Intratumoral FGFR2 amplification heterogeneity was assessed in sections from all cases with FGFR2 amplification, and was defined as the presence of areas with different FISH scores within the same tumor in full sections. Amplification was observed in 3 patients (15.7%). Interestingly, in one case amplification was observed in primary ovarian tumor but not in the metastatic nor in relapse samples. In two other cases the FGFR2 amplification was detected in relapse samples and in primary metastatic samples but not in ovary. High-level polysomy (HLP) was observed in 10 patients (55.5%). In all of those patients HLP was revealed in the samples of relapse. In 3 patients HLP was found in all 3 samples, in 3 cases HLP was observed only after relapse, in 4 cases HLP in metastasis sample was the same as in relapse sample, but it wasn't observed in ovary samples. Eight of 13 FGFR2 amplified ovarian cancers or tumors with HLP (61.5%) displayed intratumoral heterogeneity within full sections. In 5 (27.8%) cases neither amplification nor high level polysomy was observed. In conclusion, this is the first study of FGFR2 FISH in serous ovarian adenocarcinoma, demonstrating a FGFR2 amplification and HLP in primary tumor, primary metastases and relapse. Furthermore, we found evidence for intratumoral heterogeneity of FGFR2 amplification and HLP in about 61.5% of ovarian cancers. This study was supported by grant from the “Oncoprogress Foundation”. FGFR2 amplification and high-level polysomy in patients with serous cancer (13 patients)N (%), patientsPrimary tumor (N samples)Primary metastasis (N samples)Relapse (N samples)Amplification3 (15.7%)122High level polysomy10 (55.5%)3410 Citation Format: Alexandra Tyulyandina, Ilya Tsimafeyeu, Irina Demidova, Marina Gikalo, Sergei Tjulandin. FGFR2 amplification in serous ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4586.