e20631 Background: The prognostic and predictive value of KRAS mutation in advanced NSCLC is still debatable. In TAILOR (NCT00637910) trial EGFR wild-type patients were randomized to receive 2nd line erlotinib versus docetaxel, and no interaction was detected according to KRAS mutational status. Recent evidences indicate that the concurrent mutation of KRAS and LKB1 (key factor for cell metabolism) may be associated with worse prognosis. Methods: Availableformalin-fixed embeddedtissue samples with annotated clinical data from TAILOR were gathered. Customized deep sequencing (Ion proton Technology) of 111 genes most frequently associated with cancer, was performed; 5% of frequency was used to identify mutations. Association between genes and clinical features was performed with non-parametric tests; Cox regression analysis was used to assess the prognostic and predictive value of LKB1. Results: 123 out of 222 (55%) randomized patients had available tissue and were successfully sequenced. 42/123 (34%) patients had a KRAS mutation. KRAS and LKB1 mutations were found in 11/42 (26%) KRAS patients, while only 6 patients had a LKB1 mutation without KRAS. The presence of a concurrent KRAS-LKB1 mutation did not adversely influence progression-free (PFS) or overall (OS) survival [hazard ratio (HR) PFS 1.08, 95% confidence interval (CI) 0.57-2.05, P = 0.81; OS 1.09, 95% CI 0.56-2.14, P = 0.78]. Patients receiving docetaxel experienced longer survival regardless of the KRAS-LKB1 mutational status (mutated KRAS-LKB1 HR 0.42, 95% CI 0.08-2.29; wild-type KRAS-LKB1 HR 1.16, 95% CI 0.72-1.87, P = 0.55; interaction P = 0.10). Conclusions: Although the significant attrition and the limited number, these data generate the hypothesis that the concurrent mutation of KRAS and LKB1 may potentially be associated with resistance to erlotinib. Overall, the coexistence of mutation in KRAS and LKB1 is not associated with worse prognosis in NSCLC. For these patients refractory to EGFR targeting, metabolic strategies represent a future research opportunity.