The dual pathway inhibitor rigosertib is effective in direct-patient tumor xenografts of head and neck squamous cell carcinomas

ABSTRACT: Rigosertib treatment of head and neck squamous cell cancer The dual pathway inhibitor rigosertib inhibits phosphoinositide 3-kinase (PI3K) pathway activation as well as polo-like kinase 1 (PLK1) activity across a broad spectrum of cancer cell lines. The importance of PIK3CA alterations in head and neck squamous cell cancer (HNSCC) has raised interest in exploring agents targeting PI3K, the product of PIK3CA. The genetic and molecular basis of rigosertib treatment response was investigated in a panel of 16 HNSCC cell lines, and direct patient tumor xenografts from 8 HNSCC patients (4 HPV16-positive). HNSCC cell lines and xenografts were characterized by pathway enrichment gene expression analysis, exon sequencing, gene copy number, western blotting, and IHC. Rigosertib had potent antiproliferative effects on 11 of the 16 HPV- HNSCC cell lines. Treatment sensitivity was confirmed in two cell lines using an orthotopic in vivo xenograft model. Growth reduction after rigosertib treatment was observed in 3/8 HNSCC direct patient tumor lines. The responsive tumor lines carried a combination of a PI3KCA activating event (amplification or mutation) and a p53 inactivating event (either HPV16-mediated or mutation-mediated TP53 inactivation). In this study, we evaluated the in vitro and in vivo efficacy of rigosertib in both HPV+ and HPV- HNSCCs focusing on inhibition of the PI3K pathway. Although consistent inhibition of the PI3K pathway was not evident in HNSCC, we identified a combination of PI3K/TP53 events necessary, but not sufficient for rigosertib-sensitivity. Sixteen HNSCC lines data were profiled at baseline to find differentially expressed genes and pathways sensitive to rigosertib.

ORGANISM(S): Homo sapiens

SUBMITTER: Aik Choon Tan 

PROVIDER: E-GEOD-47864 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress