Different prognostic impact of STK11 mutations in non-squamous non-small-cell lung cancer

Abstract

STK11 is commonly mutated in lung cancer. In light of recent experimental data showing that specific STK11 mutants could acquire oncogenic activities due to the synthesis of a short STK11 isoform, we investigated whether this new classification of STK11 mutants could help refine its role as a prognostic marker. We conducted a retrospective high-throughput genotyping study in 567 resected non-squamous non-small-cell lung cancer (NSCLC) patients. STK11 exons 1 or 2 mutations (STK11ex1-2) with potential oncogenic activity were analyzed separately from exons 3 to 9 (STK11ex3-9). STK11ex1-2 and STK11ex3-9 mutations occurred in 5% and 14% of NSCLC. STK11 mutated patients were younger (P = .01) and smokers (P< .0001). STK11 mutations were significantly associated with KRAS and inversely with EGFR mutations. After a median follow-up of 7.2 years (95%CI 6.8-.4), patients with STK11ex1-2 mutation had a median OS of 24 months (95%CI 15-57) as compared to 69 months (95%CI 56-93) for wild-type (log-rank, P = .005) and to 91 months (95%CI 57-unreached) for STK11ex3-9 mutations (P = .003). In multivariate analysis, STK11ex1-2 mutations remained associated with a poor prognosis (P = .002). Results were validated in two public datasets. Western blots showed that STK11ex1-2 mutatedtumors expressed short STK11 isoforms. Finally using mRNAseq data from the TCGA cohort, we showed that a stroma-derived poor prognosis signature was enriched in STK11ex1-2 mutated tumors. All together our results show that STK11ex1-2 mutations delineate an aggressive subtype of lung cancer for which a targeted treatment through STK11 inhibition might offer new opportunities.