Effects of Co-occurring Genomic Alterations on Outcomes in Patients with KRAS-Mutant Non-Small Cell Lung Cancer

Management of KRAS-Mutant Non-Small Cell Lung Cancer in the Era of Precision Medicine

OPINION STATEMENT

The discovery of genomic alterations that drive the development and progression of non-small cell lung cancer (NSCLC) has transformed how we treat metastatic disease. However, the promise of precision medicine remains elusive for the most commonly mutated oncogene in NSCLC, KRAS. This is perhaps due to the substantial heterogeneity within the broader genomic context of KRAS-mutant NSCLC. At this time, approaches for treating metastatic KRAS-mutant NSCLC mirror those for treating NSCLC that lacks a known driver mutation, including standard chemotherapeutic and immunotherapeutic approaches. Ongoing research aims to define further subgroups of KRAS-mutant NSCLC based on mutation subtype and co-occurring mutations. These efforts offer the potential to optimize standard-of-care regimens within these emerging subgroups and harness innovative strategies to realize precision medicine in this setting.

STK11/LKB1 Mutations and PD-1 Inhibitor Resistance in KRAS-Mutant Lung Adenocarcinoma

KRAS is the most common oncogenic driver in lung adenocarcinoma (LUAC). We previously reported that STK11/LKB1 (KL) or TP53 (KP) comutations define distinct subgroups of KRAS-mutant LUAC. Here, we examine the efficacy of PD-1 inhibitors in these subgroups. Objective response rates to PD-1 blockade differed significantly among KL (7.4%), KP (35.7%), and K-only (28.6%) subgroups (P < 0.001) in the Stand Up To Cancer (SU2C) cohort (174 patients) with KRAS-mutant LUAC and in patients treated with nivolumab in the CheckMate-057 phase III trial (0% vs. 57.1% vs. 18.2%; P = 0.047). In the SU2C cohort, KL LUAC exhibited shorter progression-free (P < 0.001) and overall (P = 0.0015) survival compared with KRAS^MUT;STK11/LKB1^WT LUAC. Among 924 LUACs, STK11/LKB1 alterations were the only marker significantly associated with PD-L1 negativity in TMB^{Intermediate/High} LUAC. The impact of STK11/LKB1 alterations on clinical outcomes with PD-1/PD-L1 inhibitors extended to PD-L1-positive non-small cell lung cancer. In Kras-mutant murine LUAC models, Stk11/Lkb1 loss promoted PD-1/PD-L1 inhibitor resistance, suggesting a causal role. Our results identify STK11/LKB1 alterations as a major driver of primary resistance to PD-1 blockade in KRAS-mutant LUAC.Significance: This work identifies STK11/LKB1 alterations as the most prevalent genomic driver of primary resistance to PD-1 axis inhibitors in KRAS-mutant lung adenocarcinoma. Genomic profiling may enhance the predictive utility of PD-L1 expression and tumor mutation burden and facilitate establishment of personalized combination immunotherapy approaches for genomically defined LUAC subsets. Cancer Discov; 8(7); 822-35. ©2018 AACR.See related commentary by Etxeberria et al., p. 794This article is highlighted in the In This Issue feature, p. 781.

TP53, STK11, and EGFR Mutations Predict Tumor Immune Profile and the Response to Anti-PD-1 in Lung Adenocarcinoma

Purpose: By unlocking antitumor immunity, antibodies targeting programmed cell death 1 (PD-1) exhibit impressive clinical results in non-small cell lung cancer, underlining the strong interactions between tumor and immune cells. However, factors that can robustly predict long-lasting responses are still needed.Experimental Design: We performed in-depth immune profiling of lung adenocarcinoma using an integrative analysis based on immunohistochemistry, flow-cytometry, and transcriptomic data. Tumor mutational status was investigated using next-generation sequencing. The response to PD-1 blockers was analyzed from a prospective cohort according to tumor mutational profiles and PD-L1 expression, and a public clinical database was used to validate the results obtained.Results: We showed that distinct combinations of STK11, EGFR, and TP53 mutations were major determinants of the tumor immune profile (TIP) and of the expression of PD-L1 by malignant cells. Indeed, the presence of TP53 mutations without co-occurring STK11 or EGFR alterations (TP53-mut/STK11-EGFR-WT), independently of KRAS mutations, identified the group of tumors with the highest CD8 T-cell density and PD-L1 expression. In this tumor subtype, pathways related to T-cell chemotaxis, immune cell cytotoxicity, and antigen processing were upregulated. Finally, a prolonged progression-free survival (PFS: HR = 0.32; 95% CI, 0.16-0.63, P < 0.001) was observed in anti-PD-1-treated patients harboring TP53-mut/STK11-EGFR-WT tumors. This clinical benefit was even more remarkable in patients with associated strong PD-L1 expression.Conclusions: Our study reveals that different combinations of TP53, EGFR, and STK11 mutations, together with PD-L1 expression by tumor cells, represent robust parameters to identify best responders to PD-1 blockade. Clin Cancer Res; 24(22); 5710-23. ©2018 AACR.

NRF2 addiction in cancer cells

The Kelch‐like ECH‐associated protein 1/nuclear factor erythroid‐derived 2‐like 2 (KEAP1‐NRF2) system is a pivotal defense mechanism against oxidative and electrophilic stress. Although transient NRF2 activation in response to stress is beneficial for health, persistent NRF2 activation in cancer cells has deleterious effects on cancer‐bearing hosts by conferring therapeutic resistance and aggressive tumorigenic activity on cancer cells. Because NRF2 increases the antioxidant and detoxification capability of cancer cells, persistently high levels of NRF2 activity enhance therapeutic resistance of cancer cells. NRF2 also drives metabolic reprogramming to establish cellular metabolic processes that are advantageous for cell proliferation in cooperation with other oncogenic pathways. As a result of these advantages, cancer cells with persistent activation of NRF2 often develop “NRF2 addiction” and show malignant phenotypes leading to poor prognoses in cancer patients. Inhibition of NRF2 is a promising therapeutic approach for NRF2‐addicted cancers and NRF2 inhibitors are being actively developed. However, giving systemic NRF2 inhibitors might have undesirable effects on cancer‐bearing hosts, considering the central roles of NRF2 in cytoprotection. To avoid these side‐effects, new therapeutic targets besides NRF2 for NRF2‐addicted cancers have been actively explored. This review introduces recent studies describing the development and characterization of NRF2‐addicted cancers, as well as their potential therapeutic targets. Expected advances in diagnostic and therapeutic interventions for NRF2‐addicted cancers are also discussed.