Prognostic impact of XPO1 mutations in metastatic non-small cell lung cancer (NSCLC).

Abstract

e20533 Background: Nuclear protein transport is essential in guiding the organized traffic of important proteins and RNAs between the nucleus and cytoplasm of the cell. Export of proteins from the nucleus is exclusively regulated by Exportin 1(XPO1). In cancer, XPO1 is universally hyperactive and can promote the export of important tumor suppressors to the cytoplasm, leading to their functional inactivation. XPO1 is aberrantly over expressed in NSCLC and this over expression has been linked to poor overall survival. The underlying mechanisms of XPO1 over expression are not known. Currently there are no studies evaluating the impact of XPO1 mutations on NSCLC incidence and therapy resistance. Additionally, there are no studies that examined the XPO1 related pathways in NSCLC harboring co-alterations with other driver mutations such as EGFR or ALK. Methods: Tumor samples were analyzed using next-generation sequencing (NextSeq, 592 Genes), IHC, and whole transcriptome sequencing (WTS ,NovaSeq) (Caris Life Sciences, Phoenix, AZ). PD-L1 expression was tested by IHC using 22c3 (Dako) and TPS scores were reported (cutoff > 1%). TMB was measured by totaling somatic mutations (TMB-high cut-off ³ 10 mutations per Megabase). Gene fusions were detected by RNA sequencing using either the Archer FusionPlex panel or WTS. Survival was extracted from insurance claims data and calculated from time of tissue collection to last contact using Kaplan-Meier estimate. Statistical significance was determined using chi-square and Wilcoxon rank sum test and adjusted for multiple comparisons. Results: Among 18,218 NSCLC tumors sequenced, 26 harbored XPO1 mutations. XPO1 mutant tumors were more likely to be TMB High(79% vs. 52%, p = 0.007) and less likely to have high PDL1(32% vs. 68%, p = 0.03). KRAS mutations were seen in 19%(n = 5), EGFR mutation were rare (n = 2), and no targetable fusions were seen. Among the 17,449 NSCLC tumors with clinical data, there were 24 XPO1 mutant tumors with no histology imbalance observed in mutant vs. wild-type(WT). Comparison of survival in the NSCLC group between XPO1 mutant and WT showed a negative association with a hazard ratio(HR) of 1.932 (95% CI: 1.144- 3.264 p = 0.012). Comparing the survival within the subgroup with confirmed adenocarcinoma histology (9973 XPO1 WT and 14 XPO1 mutant) showed a similar negative correlation in survival with a HR of 2.156 (95% CI: 1.027- 4.525 P = 0.037). Conclusions: Presence of XPO1 pathogenic mutations was associated with a poor survival in both the entire NSCLC cohort and the adenocarcinoma subgroup. Further studies of this negative association at the molecular level along with effect of other co-existing mutations can result in development of novel treatment strategies.