Abstract 3258: Gene expression and mutation analysis in human osteosarcoma xenograft models associated with combination activity of lenvatinib with etoposide and ifosfamide

Objectives: Lenvatinib mesilate (lenvatinib) is a selective inhibitor of VEGFR1-3, and other proangiogenic and oncogenic pathway-related receptor tyrosine kinases (RTKs) including fibroblast growth factor receptors (FGFR1-4), the platelet-derived growth factor receptor (PDGFR) α, KIT, and RET. Lenvatinib showed antitumor activity against various tumor types mainly through its inhibition of angiogenesis. The triple combination of lenvatinib, ifosfamide, and etoposide was effective against human pediatric osteosarcoma xenografts in nude mice. The objective of the study was to identify genes and pathways associated with tumor response to combination of Lenvatinib with etoposide (ETP) and ifosfamide (IFM). Methods: Five human osteosarcoma cell lines (143B, HuO9, G292 clone A141B1, Saos-2, HOS) were grown in vitro and were used for DNA isolation and subsequent whole exome sequencing to determine their mutational profiles. Thirty tissue samples from tumor xenografts in nude mice were used for RNA isolation and subsequent transcriptional profiling using RNA sequencing. Each tumor xenograft model was represented by 6 samples isolated from 6 different mice. Results: We performed mutation and gene expression profiling of 5 human pediatric osteosarcoma xenograft models using whole exome and RNA sequencing. Three of the models (G292, 143B and HOS) showed enhanced antitumor activity when lenvatinib was combined with IFM and ETP. We identified genes and signaling pathways associated with tumor response to the combination treatment. Top three pathways identified were hepatic fibrosis (p = 1.7*10-7), molecular mechanism of cancer (p = 1.3*10-4) and role of osteoblasts, osteoclasts and chondrocytes in rheumatoid arthritis (p = 3.3*10-4). Genes from the pathways were related to cell differentiation and RTK. Hierarchical clustering of the models based on genes from the FGF pathways showed different expression patterns between models. A large fraction of genes from the FGF pathway showed statistically significant differences between the models. For example FGFR1 showed highest expression in G292, FGFR2 in Saos2, FGFR4 in 143B and HOS and FGFR3 in Hu09 and Saos2. The sequencing analysis identified 27 genes with previously reported mutations in TCGA with unique mutation or wild type status in the models with enhanced anti-tumor activity for combination of lenvatinib with IFM and ETP combination. Conclusions: Gene expression analysis by RNAseq and whole exome sequencing showed variation between the xenograft models. Based on the differences we were able to identify genes and signaling pathways associated with anti-tumor activity of combination treatment of lenvatinib with IFM and ETP compared to combination of IFM and ETP. Citation Format: Zoltan Dezso, Sergei I. Agoulnik, Crystal MacKenzie, Kaoru Mitsuhashi, Kiyoshi Okamoto, Junji Matsui, Yasuhiro Funahashi. Gene expression and mutation analysis in human osteosarcoma xenograft models associated with combination activity of lenvatinib with etoposide and ifosfamide. [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 3258.