Biomarker analyses from the phase III placebo-controlled SATURN study of maintenance erlotinib following first-line chemotherapy for advanced NSCLC

Abstract

8020 Background: The SATURN (BO18192) study investigated whether erlotinib maintenance therapy improved PFS in patients (pts) with advanced NSCLC who had obtained clinical benefit from 1st-line chemotherapy. This study included a prospective analysis of the prognostic/predictive value of several molecular markers. Methods: 889 pts with advanced NSCLC whose disease had not progressed following 4 cycles of 1st-line platinum-doublet chemotherapy were randomized to erlotinib 150 mg/day or placebo. Mandatory tumor specimens were collected at baseline and tested for EGFR protein expression using immunohistochemistry (IHC), EGFR gene copy number using fluorescent in-situ hybridization (FISH), and EGFR and KRAS somatic mutations using DNA sequencing. Pts were stratified according to EGFR IHC status (any membranous staining in ≥10% tumor cells used as cut-off); the co-primary endpoint was PFS in EGFR IHC+ pts. Baseline whole blood samples were obtained for genotyping of EGFR (intron 1 CA-repeat polymorphisms). Results: In the overall population, erlotinib significantly prolonged PFS vs placebo (HR 0.71, p<.0001; primary endpoint). The co-primary endpoint was also met, with erlotinib significantly improving PFS in the EGFR IHC+ group (HR 0.69, p<.0001). Many tumor samples were assessable for molecular marker status (see table). Biomarker data suggest that patients derived a PFS benefit with erlotinib irrespective of EGFR FISH or EGFR intron 1 CA-repeat status. The magnitude of benefit with erlotinib was similar in both KRAS-mutant and KRAS wild-type pts. Conclusions: This is the largest biomarker analysis performed for erlotinib in a randomized, placebo-controlled setting, and answers key scientific questions regarding the prognostic and predictive value of potential biomarkers of efficacy. Full data will be presented. [Table: see text] [Table: see text]