Predicting sensitivity to azacytidine in non-small cell cancer lines by absence of activating mutations.

e18147 Background: A completed clinical trial has demonstrated activity of a combination of epigenetic therapies: entinostat, a histone deacetylase inhibitor, and azacytidine (AZA), a hypomethylating agent. A plasma-based biomarker assaying methylation status of key gene promoters from circulating DNA was developed. In order to test the relationship of activating mutations to sensitivity to epigenetic therapy, we treated non-small cell lung cancer (NSCLC) lines with AZA and assessed tumor growth in xenografts. Tumor from patients on trial was analyzed for mutational status. Methods: Nine NSCLC lines were treated in vitro for 72 hours with 500 nM AZA and injected to form flank tumors in NOG mice. Four lines contain no activating mutations. Of the five mutant lines, three were KRAS and two were EGFR mutations. Lines with no activating mutations are termed “mutation-negative” for known oncogenic drivers. Growth of mock versus treated tumors was compared over time to determine treatment phenotypes. Lines were...