Passive Smoking-Induced Mutagenesis as a Promoter of Lung Carcinogenesis.

INTRODUCTION: The International Agency for Research on Cancer has classified passive smoking (PS) or secondhand smoke exposure as a group 1 carcinogen linked to lung cancer. However, in contrast to active smoking, the mutagenic properties of PS remain unclear. METHODS: A consecutive cohort of 564 lung adenocarcinoma samples from female never-smokers, who provided detailed information about their exposure to PS during adolescence and in their thirties through a questionnaire, was prepared. Of these, all 291 cases for whom frozen tumor tissues were available were subjected to whole exome sequencing to estimate tumor mutational burden, and the top 84 cases who were exposed daily, or not, to PS during adolescence, in their thirties or in both periods, were further subjected to whole genome sequencing. RESULTS: A modest yet statistically significant increase in tumor mutational burden was observed in the group exposed to PS compared with the group not exposed to PS (median values = 1.44 versus 1.29 per megabase, respectively; p = 0.020). Instead of inducing driver oncogene mutations, PS-induced substantial subclonal mutations exhibiting APOBEC-type signatures, including SMAD4 and ADGRG6 hotspot mutations. A polymorphic APOBEC3A/3B allele-specific to the Asian population that leads to up-regulated expression of APOBEC3A accentuated the mutational load in individuals exposed daily to PS during adolescence. CONCLUSIONS: This study reveals that PS-induced mutagenesis can promote lung carcinogenesis. The APOBEC3A/3B polymorphism may serve as a biomarker for identifying passive nonsmoking individuals at high risk of developing lung cancer.

Evaluating the potential of immunotherapy and chemoimmunotherapy in the treatment of elderly non-small cell lung cancer patients: A real-world study.

BACKGROUND: Immune checkpoint inhibitor (ICI) has become the standard therapy for metastatic non-small cell lung cancer (NSCLC) patients. However, no robust evidence on the efficacy and safety of ICI in elderly NSCLC patients has been established. MATERIALS AND METHODS: This retrospective study aimed to assess the efficacy and safety of ICI in elderly NSCLC patients. NSCLC patients treated with ICI monotherapy or chemoimmunotherapy (CIT) between 2016 and 2022 were divided into two cohorts according to the age: the Elderly cohort (patients aged ≥ 75 years) and the Nonelderly cohort (patients aged < 75 years). The progression-free survival (PFS), tumor response, and frequency of immune-related adverse events (irAEs) were compared between the two cohorts. RESULTS: A total of 111 NSCLC patients were included in this study (41 patients in the Elderly cohort and 70 patients in the Nonelderly cohort). The PFS (5.6 months vs. 6.3 months, P = 0.98), response rate (36.6% vs. 44.9%, P = 0.51), and disease control rate (80.5% vs. 76.8%, P = 0.83) were not significantly different between the two cohorts. In a subgroup analysis, stratified according to PD-L1 expression (low vs. high) and ICI treatment mode (ICI monotherapy vs. CIT), the PFSs of both cohorts were also not significantly different, regardless of PD-L1 expression. Moreover, the frequency of irAEs did not significantly differ between elderly and nonelderly NSCLC patients (21/41 [51.2%] vs. 38/70 [54.3%], P = 0.91). CONCLUSION: The efficacy and safety of ICI in elderly NSCLC patients were not inferior to those in younger patients.

An ATR-PrimPol pathway confers tolerance to oncogenic KRAS-induced and heterochromatin-associated replication stress.

Activation of the KRAS oncogene is a source of replication stress, but how this stress is generated and how it is tolerated by cancer cells remain poorly understood. Here we show that induction of KRASG12V expression in untransformed cells triggers H3K27me3 and HP1-associated chromatin compaction in an RNA transcription dependent manner, resulting in replication fork slowing and cell death. Furthermore, elevated ATR expression is necessary and sufficient for tolerance of KRASG12V-induced replication stress to expand replication stress-tolerant cells (RSTCs). PrimPol is phosphorylated at Ser255, a potential Chk1 substrate site, under KRASG12V-induced replication stress and promotes repriming to maintain fork progression and cell survival in an ATR/Chk1-dependent manner. However, ssDNA gaps are generated at heterochromatin by PrimPol-dependent repriming, leading to genomic instability. These results reveal a role of ATR-PrimPol in enabling precancerous cells to survive KRAS-induced replication stress and expand clonally with accumulation of genomic instability.

Non-inferior clinical outcomes of immune checkpoint inhibitors in non-small cell lung cancer patients with interstitial lung disease.

OBJECTIVES: The efficacy of immune checkpoint inhibitors (ICIs) in non-small-cell lung cancer (NSCLC) patients with pre-existing interstitial lung disease (ILD) is unclear. MATERIALS AND METHODS: Retrospective medical data from advanced or recurrent NSCLC patients who were treated with nivolumab or pembrolizumab at ten institutions in Japan between January 2016 and September 2018 were analyzed. Eligible patients were divided into two groups according to the presence of pre-existing ILD. RESULTS: A total of 461 NSCLC patients were enrolled, 412 without ILD (Non-ILD group) and 49 with ILD (ILD group). The response rate (RR) and disease control rate (DCR) of the ILD group were not inferior to those of the Non-ILD group [RR: 49.0 % (24/49) vs. 30.1 % (124/412), P < 0.01 and DCR: 69.4 % (34/49) vs. 51.2 % (211/412), P = 0.016, respectively]. Non-inferior outcomes were also observed with respect to progression-free survival (PFS) and overall survival (OS) (median PFS: 5.9 months vs. 3.5 months, P = 0.14 and median OS: 27.8 months vs. 25.2 months, P = 0.74 in the ILD and Non-ILD groups, respectively). Among immune-related adverse effects (irAEs), checkpoint inhibitor pneumonitis (CIP) was more frequently observed among NSCLC patients in the ILD group [30.6 % (15/49) vs. 9.5 % (39/412), P < 0.01]. The frequency of irAEs other than CIP and infusion reactions was not significantly different between the ILD group and the Non-ILD group. CONCLUSION: These results suggest that the clinical outcomes of ICIs are not significantly affected by pre-existing ILD despite the increased frequency of CIP. NSCLC patients with ILD are therefore probable candidates for ICIs.