Randomized phase II study of erlotinib (E) or intercalated E with carboplatin/paclitaxel (CP) in chemotherapy-naive advanced NSCLC: Correlation of biomarker status and clinical benefit

Abstract

8026 Background: E plus chemotherapy showed no additive effects in NSCLC but preclinical studies suggested that intercalation of E and chemotherapy could give synergy. Clinical studies suggested that EGFR mutations could aid in pt selection. KRAS mutation status of tumors was also evaluated. We conducted a randomized phase II study of E and E intercalated with CP in pts with chemonaive NSCLC. Methods: Stage IIIB/IV EGFR+ NSCLC pts were randomized to E 150 mg/d or CP d1 plus E days 2–15 q21 days (ECP). After 4 cycles, E continued until PD. Tumor tissue was evaluated by IHC (EGFR), FISH (EGFR gene copy number), and PCR amplification followed by DNA sequencing (EGFR and KRAS mutations). Results: Among 143 pts randomized 53% EGFR FISH+; 13% activating EGFR mutations and 8% non-activating EGFR mutations (evaluable samples=114); and 22% KRAS mutations (evaluable samples=130). No pt had both EGFR and KRAS mutations. EGFR-activating mutations were higher among females (19% vs 6% males), adenocarcinoma histology (17% vs 0% others), Asians (45% vs 7% non-Asian), and never smokers (29% vs 7% former and 0% current); KRAS mutations were higher in current smokers (41% vs 27% former and 0% never) and adenocarcinoma histology (22% vs 18% squamous). In the E arm, 6-mo PFS probability for the efficacy evaluable population (n=69) was significantly higher in pts with EGFR activating mutations vs no mutations (89% vs 25%, HR=0.17, P=0.001), numerically higher in pts with EGFR FISH+ vs FISH- (40% vs 22%, HR=0.61, P=0.07), and with KRAS wild type vs mutation+ (38% vs 12%, HR=0.56, P=0.10). Response rates, PFS and OS by type of EGFR/KRAS mutation will be presented. In the ECP arm, 6-mo PFS probability for the efficacy evaluable population (n=68) was numerically higher in pts with EGFR activating mutations (42% vs 29%, HR=0.72, P=0.53), numerically higher in pts with wild type KRAS (32% vs 9%, HR=0.57, P=0.08), and numerically lower in pts with EGFR FISH+ vs FISH- (23% vs 30%, HR=0.93, P=0.78). Conclusions: Activating EGFR mutations correlate with increased 6 mo PFS probability in 1st line therapy with E. EGFR FISH + and absence of KRAS mutation trend towards increased 6 mo PFS rate with E. [Table: see text]