Effect of STK11 mutations on efficacy of PD-1 inhibition in non-small cell lung cancer (NSCLC) and dependence on KRAS mutation status.

Abstract

e15113 Background: STK11 mutations ( STK11m) have been associated with resistance to ICI in KRAS-mutant ( KRASm) NSCLC. Whether STK11m status also impacts clinical outcomes to ICI in KRAS wild-type (wt) NSCLC is unknown. Methods: We analyzed clinical outcomes of patients (pts) with NSCLC treated with ICI according to KRAS and STK11 mutation status in independent discovery (DFCI+MGH) and validation (MSKCC) cohorts. TCGA and xCell data were interrogated to identify differences in tumor gene expression and tumor immune cell subsets, respectively, according to KRAS/ STK11 co-mutation status. Results: Of 1195 pts with advanced nonsquamous NSCLC treated with ICI, 447 (37.4%) had a KRASm, 252 (21.1%) had pathogenic STK11 mutations, and 128 (10.7%) had concurrent KRASm and STK11m. ICI outcomes for the discovery and validation cohorts in KRASm and KRASwt cases by STK11 mutation status are shown in Table. In the combined cohort (discovery+validation), STK11m was associated with significantly worse outcomes to ICI among KRASm cases: ORR 10.2% vs 30.7%, P < 0.001; median progression-free survival (mPFS): 2.0 vs 4.8 months (mo), HR:0.49 [95%CI:0.39-0.61], P < 0.0001; median overall survival (mOS): 6.1 vs 16.9 mo, HR:0.50 [95%CI:0.39-0.63], P < 0.0001. In multivariable analysis, STK11m was associated with significantly shorter PFS (HR:0.56, P = 0.002) and OS (HR:0.57, P = 0.006). By contrast, STK11m had no impact on ICI outcomes among KRASwt cases: ORR 24.2% vs 19.2%, P = 0.21; mPFS: 2.5 vs 2.8 mo, HR:0.98 [95%CI:0.79-1.21], P = 0.89; mOS: 12.0 vs 11.5 mo, HR:1.06 [95%CI:0.85-1.33], P = 0.57. Among KRASwt cases, STK11m had no impact on ICI outcomes among both smokers and never smokers, when analyzed separately. Gene ontology analysis from TCGA revealed that among KRASm but not KRASwt NSCLC, STK11m was associated with the downregulation of MHC class II-related genes (P = 0.02). Cell subset transcriptome analysis showed significantly lower proportions of M1 macrophages among KRASm/ STK11m but not among KRASwt/ STK11m NSCLCs (P < 0.01). Conclusions: STK11m are associated with resistance to ICI in KRASm but not KRASwt NSCLC. STK11m/ KRASm vs STK11m/ KRASwt NSCLC have distinct immunophenotypes. [Table: see text]