CPS1 and adenocarcinoma: To further establish the clinical relevance of the synthetic lethality of DEX in LKB1-mutant lung cancer, we chose a NSCLC PDX adenocarcinoma (LTL-657) from a bank of NSCLC PDXs based on high expression of CPS1 and somatic mutations of KRAS and LKB1 (Figure 4A).