LKB1 deficiency is found in approximately 10% of non-small cell lung cancer harboring Kras mutation. Loss of LKB1 has been associated with increased metastatic rates and decreased survival in patients. Currently, no effective therapy has been developed against this subtype of lung cancer. LKB1 can regulate multiple cellular activities. One of the most well-studied functions is its regulation on cell metabolism through AMPK signaling pathway. How LKB1 loss globally impacts NSCLC metabolism has not been well understood yet. Using isotope-labeled substrate tracing approach, we found an increase of specially-labeled intermediates in pentose phosphate pathway (PPP) that may suggest upregulation of PPP activity. In addition, we also performed an unbiased drug screen that showed higher sensitivity to an mTOR inhibitor in Kras and LKB1 double mutant lung cancer cells relative to cancer cells under other genetic background. These data suggest that loss of LKB1 may upregulate biosynthetic reactions in Kras mutant NSCLC and render these cells sensitive to inhibitors in biosynthesis. These findings may provide new insights in developing therapeutic agents targeting Kras MT /LKB1 MT NSCLC. Citation Format: Tingyu Liu, Erin Sennott, Zhengjie Zhong, Mya Steadman, Kelly Marsh, Jonathan Hurov, Cyril Benes, Jeffrey A. Engelman. LKB1 deficiency is associated with a unique metabolic signature in Kras mutant non-small cell lung cancer (NSCLC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 7.