Vimentin expression correlates with immune checkpoint inhibitor efficacy in non-small cell lung cancer.

BACKGROUND: Although vimentin is often expressed in non-small cell lung cancer (NSCLC), the association between vimentin expression and immune-checkpoint inhibitor (ICI) efficacy remains unclear. METHODS: This retrospective multicenter study enrolled patients with NSCLC who received ICI treatment between December 2015 and July 2020. The authors constructed tissue microarrays and performed immunohistochemical staining with vimentin. They analyzed the relationship between vimentin expression rate and objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). RESULTS: Immunohistochemically evaluable specimens on microarray blocks were available for 397 patients, of whom 343 (86%) were negative (<10%), 30 (8%) were positive (10%-49%), and 24 (6%) were highly positive (≥50%) for vimentin expression. Both rates of programmed death-ligand 1 (PD-L1) tumor proportion score ≥1% and ≥50% were significantly higher in the vimentin-positive group (≥10%) than the vimentin-negative group (<10%) (96% vs. 78%, p = .004; 64% vs. 42%, p = .006, respectively). In patients treated with ICI monotherapy, ORR, PFS, and OS were significantly better in the vimentin-positive group (10%-49%) than in the vimentin-negative group (<10%) (54% vs. 25%, p = .003, median = 7.9 vs. 3.2 months, p = .011; median = 27.0 vs. 13.6 months, p = .015, respectively), whereas there was no significant difference in PFS and OS between the vimentin highly positive group (≥50%) and the vimentin-negative group (<10%) (median = 3.4 vs. 3.2 months, p = .57; median = 7.2 vs. 13.6 months, p = .086, respectively). CONCLUSIONS: Vimentin expression correlated with PD-L1 expression and ICI efficacy. PLAIN LANGUAGE SUMMARY: We constructed tissue microarrays and performed immunohistochemical staining with vimentin on 397 patients with advanced non-small cell lung cancer who were treated with immune-checkpoint inhibitor (ICI). The vimentin-positive group who were treated with ICI monotherapy showed significantly better objective response rate, progression-free survival, and overall survival than the vimentin negative group. The measurement of vimentin expression will aid in determining appropriate immunotherapy strategies.

Vascular endothelial growth factor receptor 2 expression and immunotherapy efficacy in non-small cell lung cancer.

It is unclear whether tumor vascular endothelial growth factor receptor 2 expression affects the therapeutic efficacy of immune-checkpoint inhibitors and antiangiogenic agents. This retrospective, multicenter study included patients with advanced non-small cell lung cancer who were treated with immune-checkpoint inhibitors. We constructed tissue microarrays and performed immunohistochemistry with an anti-vascular endothelial growth factor receptor 2 antibody. We analyzed immune and tumor cell staining separately in order to determine their correlation with the objective response rate, progression-free survival, and overall survival in patients receiving immune-checkpoint inhibitors. Of 364 patients, 37 (10%) expressed vascular endothelial growth factor receptor 2 in immune cells and 165 (45%) in tumor cells. The objective response rate, progression-free survival, and overall survival were significantly worse in patients treated with immune checkpoint inhibitor monotherapy who expressed vascular endothelial growth factor receptor 2 in immune cells than those who did not (10% vs 30%, p = 0.028; median = 2.2 vs 3.6 months, p = 0.012; median = 7.9 vs 17.0 months, p = 0.049, respectively), while there was no significant difference based on tumor cell expression (24% vs 30%, p = 0.33; median = 3.1 vs 3.5 months, p = 0.55; median = 13.6 vs 16.8 months, p = 0.31). There was no significant difference in overall survival between patients treated with and without antiangiogenic agents in any treatment period based on vascular endothelial growth factor receptor 2 expression. Immune checkpoint inhibitor efficacy was limited in patients expressing vascular endothelial growth factor receptor 2 in immune cells.

Phase 1b study of ramucirumab in combination with erlotinib or osimertinib for untreated EGFR-mutated non-small cell lung cancer patients with asymptomatic brain metastases.

OBJECTIVES: The study was designed to investigate the safety of ramucirumab administered in combination with erlotinib or osimertinib for patients with untreated EGFR-mutated non-small cell lung cancer (NSCLC) and asymptomatic brain metastases, a patient subgroup in which these regimens have remained untested. MATERIALS AND METHODS: This phase 1b study (RELAY-Brain) consisted of two cohorts with three patients each. Patients with asymptomatic brain metastases received ramucirumab every 2 weeks plus either daily oral erlotinib or osimertinib until disease progression or intolerable toxicity. The primary objective was to assess dose-limiting toxicity (DLT), defined as central nervous system (CNS) hemorrhage of grade ≥ 2. RESULTS: Six patients were enrolled. Neither DLT nor serious or unexpected adverse events were observed. One treatment-related adverse event of grade ≥ 3 (hypertension of grade 3) was apparent. Common adverse events were generally manageable. The median number of ramucirumab administrations was 18.5 (range, 13 to 31), and there were no detected episodes of CNS hemorrhage. Five of the six patients showed an objective systemic response. Although only one patient had a measurable CNS lesion at baseline, a confirmed intracranial partial response was observed. CONCLUSION: Ramucirumab in combination with erlotinib or osimertinib showed safety for EGFR-mutated NSCLC with brain metastases.

Early-onset meningitis associated with atezolizumab treatment for non-small cell lung cancer: case report and literature review.

Immune checkpoint inhibitors (ICIs) have improved the overall survival of many patients with advanced cancers. However, unlike cytotoxic and targeted drugs, ICIs may cause various immune-related adverse events (irAEs). Among these irAEs, autoimmune meningitis is very rare. Here, we report a case of early-onset, atezolizumab-induced meningitis after administration of one dose of atezolizumab. A 56-year-old man with lung adenocarcinoma had received seventh-line treatment with atezolizumab when he experienced dysarthria. Blood examinations, including the measurement of electrolytes, glucose, and organ functions, were unremarkable, but enhanced head magnetic resonance imaging T1-weighted images showed meningeal enhancement. Although cerebral spinal fluid (CSF) examinations revealed elevated lymphocyte and protein levels, no cancer cells were detected in the CSF. CSF cultures and serological tests, including polymerase chain reaction for herpes simplex virus, were negative. The patient was therefore diagnosed with atezolizumab-triggered autoimmune meningitis. With steroid treatment, the patient's clinical and neurological state improved immediately and he recovered to baseline conditions. Prompt diagnosis and therapeutic intervention are essential for the effective treatment of autoimmune meningitis.

Impact of tumor microenvironment on the efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors in patients with EGFR-mutant non-small cell lung cancer.

We retrospectively investigated the impact of the tumor microenvironment (TME) on the efficacy of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) as first-line treatment in 70 patients with advanced EGFR-mutant non-small cell lung cancer and who were seen at Osaka City University Hospital (Osaka, Japan) between August 2013 and December 2017. Using immunohistochemical staining with 28-8 and D7U8C Abs, the tumor proportion score was assessed for programmed cell death-1 ligand-1 (PD-L1), as high (50% or more) or low (less than 50%), and ligand-2 (PD-L2) expression, respectively. The extent of CD8+ tumor-infiltrating lymphocytes was evaluated on a scale of 0-3, with 0-1 as low and 2-3 as high. The TME of the 52 evaluable pretreatment specimens was categorized into 4 subtypes, according to the respective PD-L1 tumor proportion and CD8+ scores, as follows: (a) high/high (13.5%, n = 7); (b) low/low (42.3%, n = 22); (c) high/low (17.3%, n = 9); and (d) low/high (26.9%, n = 14). Expression of PD-L2 was significantly the highest in type 1 (57.1% vs 4.5% vs 11.1% vs 7.1%, respectively; P = .0090). Response rate was significantly the lowest in type 1 (14.3% vs 81.8% vs 66.7% vs 78.6%, respectively; P = .0085). Progression-free survival was the shortest in type 1 and the longest in type 4 (median, 2.4 vs 11.3 vs 8.4 vs 17.5 months, respectively; P = .00000077). The efficacy of EGFR-TKIs differed according to the TME, and the phenotype with high PD-L1 and CD8+ expression might be the subset that would poorly benefit from such treatment.

Targeting of drug-tolerant persister cells as an approach to counter drug resistance in non-small cell lung cancer.

The advent of targeted therapies revolutionized treatments of advanced oncogene-driven non-small cell lung cancer (NSCLC). Nonetheless, despite initial dramatic responses, development of drug resistance is inevitable. Although mechanisms underlying acquired resistance, such as on-target mutations, bypass pathways, or lineage transformation, have been described, overcoming drug resistance remains challenging. Recent evidence suggests that drug-tolerant persister (DTP) cells, which are tumor cells tolerant to initial drug exposure, give rise to cells that acquire drug resistance. Thus, the possibility of eradicating cancer by targeting DTP cells is under investigation, and various strategies are proposed. Here, we review overall features of DTP cells, current efforts to define DTP markers, and potential therapeutic strategies to target and eradicate DTP cells in oncogene-driven NSCLC. We also discuss future challenges in the field.

Clinical significance of KL-6 in immune-checkpoint inhibitor treatment for non-small cell lung cancer.

PURPOSE: Krebs von den Lungen-6 (KL-6) functions as a tumor marker, as well as a diagnostic tool for interstitial pneumonia (IP). However, the significance of KL-6 in the immune-checkpoint inhibitor (ICI) treatment of non-small cell lung cancer (NSCLC), especially in patients without IP, is unknown. METHODS: This multicenter, retrospective study, which included patients with advanced NSCLC who received ICI therapy, analyzed the association between serum KL-6 values and ICI efficacy and the association between serum KL-6 values and ICI-induced interstitial lung disease (ILD) occurrence, focusing primarily on patients without IP. RESULTS: In total, 322 patients had available KL-6 values before ICI therapy. Among 202 patients without IP who received ICI monotherapy, the high-KL-6 group (≥ 500 U/mL) showed significantly shorter progression-free survival (PFS) and overall survival (OS) than the low-KL-6 group (< 500 U/mL) (median: 2.1 vs. 3.6 months, p = 0.048; median: 9.2 vs. 14.5 months, p = 0.035). There was no significant difference in response rate between the KL-6 high and low groups (19% vs. 29%, p = 0.14). In the multivariate analysis, high KL-6 was a significant predictor of poor PFS (hazard ratio [HR], 1.52; 95% confidence interval [CI] 1.10-2.11, p = 0.012) and OS (HR, 1.51; 95% CI 1.07 - 2.13, p = 0.019) for patients treated with ICI monotherapy. There was no significant difference in the occurrence rate of ILD between the high KL-6 and low KL-6 groups in patients with (20% vs. 15%, p = 1.00) or without IP (12% vs. 12%, p = 1.00). CONCLUSION: In ICI monotherapy for NSCLC without IP, elevated serum KL-6 levels were associated with poorer outcomes.

Influence of Smoking History on the Effectiveness of Immune-checkpoint Inhibitor Therapy for Non-small Cell Lung Cancer: Analysis of Real-world Data.

BACKGROUND/AIM: There is no real-world data in an Asian population to investigate the difference between the outcome of immune-checkpoint inhibitor (ICI) monotherapy and combination therapy for non-small cell lung cancer (NSCLC) based on smoking status. In this study, we investigated the correlation between smoking status and the efficacy of ICI therapy for NSCLC patients. PATIENTS AND METHODS: This multicentre retrospective study enrolled patients with recurrent or metastatic NSCLC who were treated using ICI therapy between December 2015 and July 2020. We analysed the objective response rate (ORR) of patients who received ICI monotherapy or combination therapy, based on smoking status using Fisher's exact test, and progression-free survival (PFS) and overall survival (OS) based on smoking status using the Kaplan-Meier method, the log-rank test, and Cox proportional hazards model. RESULTS: A total of 487 patients were included in the study. In the ICI monotherapy group, non-smokers showed significantly lower ORR and shorter PFS and OS than smokers (10% vs. 26%, p=0.002; median: 1.8 vs. 3.8 months, p<0.001; median: 8.0 vs. 15.4 months, p=0.026). In the ICI combination therapy group, non-smokers showed significantly longer OS than smokers (median: not reached vs. 26.3 months, p=0.045), and there was no significant difference in ORR and PFS between non-smokers and smokers (63% vs. 51%, p=0.43; median: 10.2 vs. 9.2 months, p=0.81). In the multivariate analysis of patients who received ICI combination therapy, the "non-smoker" status was not significantly associated with PFS [hazard ratio (HR)=1.31; 95% confidence interval (CI)=0.70-2.45, p=0.40] and OS (HR=0.40; 95% CI=0.14-1.13, p=0.083). CONCLUSION: Non-smokers showed worse outcomes than smokers with ICI monotherapy, but not with ICI combination therapy.

RBM17 Expression Is Associated With the Efficacy of ICI Monotherapy in NSCLC With Low PD-L1 Expression.

BACKGROUND/AIM: Immune checkpoint inhibitors (ICIs) are currently a standard treatment tool for non-small cell lung cancer (NSCLC). RNA-binding motif protein 17 (RBM17), a splicing factor, is frequently over-expressed in NSCLC, but little is known about the role of RBM17 in the efficacy of ICIs for NSCLC. Thus, we investigated the correlation between RBM17 expression and ICI efficacy in NSCLC. PATIENTS AND METHODS: Biopsy or surgical specimens were collected from patients with advanced or recurrent NSCLC who received ICI monotherapy or chemo-immunotherapy in a first-line setting. RBM17 expression was examined using immunohistochemistry. The correlation between the efficacy of ICI monotherapy or chemo-immunotherapy and RBM17 expression was evaluated. RESULTS: Among the 218 cases, 115 (52.8%) cases were positive for RBM17 expression. RBM17 expression was not associated with the objective response rate (ORR) or progression-free survival (PFS) in either of the ICI monotherapy or chemo-immunotherapy groups. However, among those with a low PD-L1 expression level (PD-L1 <50%; n=86), RBM17 expression was significantly associated with a better ORR (p=0.045) and a better PFS (p<0.001) in the ICI monotherapy group, and was significantly associated with a poor ORR in the chemo-immunotherapy group (p=0.041). CONCLUSION: RBM17 might be a useful predictive marker for a higher efficacy of ICI monotherapy in NSCLC patients with a low PD-L1 expression level.

A case of PD-L1 negative advanced pulmonary sarcomatoid carcinoma effectively treated with atezolizumab, carboplatin, paclitaxel, and bevacizumab.

Pulmonary sarcomatoid carcinoma (PSC) is an extremely rare neoplasm with poor prognosis and no established treatment. A 50-year-old man presented with fever, was found to have a mass measuring 14 cm in the right upper lobe of the chest, along with right pleural effusion on computed tomography (CT). Positron emission tomography-CT revealed abnormal tracer uptake in the area corresponding to the mass in the upper lobe. Hence, convex-probe endobronchial ultrasound-guided transbronchial needle aspiration was performed. Histological examination revealed dense proliferation of spindle tumor cells and no programmed death-ligand 1 (PD-L1) expression. Thus, he was diagnosed with PSC (cT4N0M1a, clinical stage IVA), and four-agent combination chemotherapy with atezolizumab, carboplatin, paclitaxel, and bevacizumab was initiated. Marked shrinkage of the mass and symptomatic improvements were observed following the treatment initiation. Tumor shrinkage was further noted after shifting to maintenance therapy with atezolizumab and bevacizumab; the patient exhibited no symptom exacerbation 2 years later and continued the treatment. Our case showed that four-agent combination chemotherapy with atezolizumab, carboplatin, paclitaxel, and bevacizumab could be an effective treatment option for advanced PSC with or without PD-L1 expression.

Association of thyroid transcription factor-1 with the efficacy of immune-checkpoint inhibitors in patients with advanced lung adenocarcinoma.

BACKGROUND: We aimed to identify the relationship between thyroid transcription factor-1 (TTF-1) expression of lung adenocarcinoma and the efficacy of immune-checkpoint inhibitor (ICI) therapy. METHODS: This retrospective multicenter study comprised patients with advanced lung adenocarcinoma treated with ICI monotherapy. We collected clinical medical records including data on TTF-1 expression and analyzed the relationship between TTF-1 expression and programmed death-ligand 1 tumor proportion score (PD-L1 TPS), objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). RESULTS: In total, 108 patients with lung adenocarcinoma were analyzed. The rate of TPS ≥1% and ≥50% in patients with positive TTF-1 expression was significantly higher than that in patients with negative TTF-1 expression (88% vs. 60%, p < 0.001; 65% vs. 24%, p < 0.001). The ORR was significantly higher in TTF-1 positive patients than in TTF-1-negative patients (38% vs. 8%, p = 0.003). Among patients with TPS ≥50% and 1%-49%, the ORR in TTF-1 positive and negative patients was 48% (26/54) versus 17% (1/6) (p = 0.21), and 32% (6/19) versus 11% (1/9) (p = 0.37), respectively. The ORR for patients with TPS <1% was 0% in both the TTF-1 negative and positive cases. The median PFS and OS was significantly longer in TTF-1-positive patients than in TTF-1-negative patients (5.4 vs. 1.6 months, p < 0.001; 18.2 vs. 8.0 months, p = 0.041). Multivariate analysis revealed that TTF-1-negative status was an independent unfavorable prognostic factor for PFS. CONCLUSION: Patients with TTF-1-positive status receiving ICI monotherapy showed better outcomes than those with TTF-1-negative lung adenocarcinoma.

SP142 evaluation contributes to the prediction of immune checkpoint inhibitor efficacy in non-small cell lung cancer with high PD-L1 expression assessed by 22C3.

Background: It remains unclear whether assessing programmed death-ligand 1 (PD-L1) expression by SP142 plus 22C3 adds value for predicting the response to immunotherapy in non-small cell lung cancer (NSCLC). Methods: This retrospective multicenter study included patients with advanced NSCLC treated with immune-checkpoint inhibitors. We constructed tissue microarrays (TMAs) and performed immunohistochemical staining with 22C3 and SP142 assays. We denoted the PD-L1 tumor proportion score (TPS) obtained from clinical medical records based on 22C3 staining as "22C3 (C)" and that obtained with 22C3 staining using our TMA as "22C3 (TMA)". SP142 staining was evaluated in both tumor cells and immune cells. We assessed the concordance between each PD-L1 assessment method and analyzed the objective response rate (ORR), progression-free survival (PFS) and overall survival (OS) based on the PD-L1 expression level determined using the 22C3 and SP142 assays. Results: In total, 288 patients were included. Among those with 22C3 (TMA) ≥50%, 60% of patients showed SP142 TC3 or IC3; among patients with 22C3 (C) <1%, 9% and 18% exhibited 22C3 (TMA) ≥1% and SP142 TC1/2/3 or IC1/2/3, respectively. Among patients with 22C3 (C) ≥50% treated with immune-checkpoint inhibitor monotherapy, the SP142 TC1/2/3 or IC1/2/3 group showed significantly better ORR, PFS and OS than the SP142 TC0 and IC0 group (54% vs. 29%, P=0.040, median =11.0 vs. 3.2 months, P=0.002, median =27.9 vs. 12.6 months, P=0.030, respectively). Multivariate analysis revealed that SP142 TC0 and IC0 was an independent unfavorable prognostic factor for PFS and OS in patients with 22C3 (C) ≥50% treated with immune-checkpoint inhibitor monotherapy. For those with 22C3 (C) ≥50% and SP142 TC0 and IC0, immune-checkpoint inhibitor concurrent with chemotherapy tended to result in a longer PFS and OS than immune-checkpoint inhibitor monotherapy (median =13.7 vs. 2.3 months, P=0.054, median = not estimable vs. 12.0 months, P=0.064, respectively). Conclusions: SP142 evaluation contributes to the prediction of immune-checkpoint inhibitor efficacy in NSCLC with high PD-L1 expression assessed by 22C3.

Mutational landscape of multiple primary lung cancers and its correlation with non-intrinsic risk factors.

Multiple primary lung cancers (MPLCs) harbour various genetic profiles among the tumours, even from individuals with same non-intrinsic risk factors. Paired mutational analyses were performed to obtain a census of mutational events in MPLC and assess their relationship with non-intrinsic risk factors. Thirty-eight surgical specimens from 17 patients diagnosed as MPLC were used. Extracted DNAs were sequenced for somatic mutations in 409 cancer-associated genes from a comprehensive cancer panel. We statistically analysed the correlation between each driver mutation frequency and non-intrinsic risk factors using Fisher's exact test, and whether genetic mutations occurred concomitantly or randomly in MPLC using an exact test. Comprehensive genetic analyses suggested different mutation profiles in tumours within the same individuals, with some exceptions. EGFR, KRAS, TP53, or PARP1 mutations were concomitantly detected in some MPLC cases. EGFR mutations were significantly more frequent in never or light smokers and females. Concomitant EGFR or KRAS mutations in MPLCs were significantly more frequent than expected by chance (P = .0023 and .0049, respectively) suggesting a more prominent role of non-intrinsic risk factors in EGFR and KRAS mutations than other mutations, which occurred more randomly. Concomitant EGFR or KRAS mutations were particularly prominent in never or light smokers and males.

Tumor microenvironment disparity in multiple primary lung cancers: Impact of non-intrinsic factors, histological subtypes, and genetic aberrations.

INTRODUCTION: Multiple primary lung cancers (MPLCs) occur in common carcinogenetic risks such as lifestyle, biological aging, immune responses, hormones, and metabolism. Although MPLCs harbor various genetic profiles within the same individuals, differences in the tumor microenvironment (TME) are unclear. We investigated the impact of genetic aberrations, non-intrinsic factors, and pathological subtypes on tumor immunity. MATERIALS AND METHODS: In total, 73 surgically resected specimens from 32 patients with MPLC were analyzed. PD-L1 expression in tumor cells (TCs) and immune cells (ICs), CD3-positive tumor-infiltrating lymphocytes (TILs), CD8/CD3 ratios, and FOXP3-positive TILs that compose TMEs were evaluated by immunohistochemistry and classified on a score of 0-2. 38 tumors were sequenced for somatic mutations in 409 cancer-associated genes. RESULTS: Females and never or light smokers had a higher incidence of PD-L1-negative tumors and a higher concordance rate. PD-L1 positivity in TCs and ICs was significantly less frequent in EGFR-mutated than in wild-type tumors. Differences in the score of TMEs were observed between the KRAS-mutated-only tumor and the KRAS and TP53-co-mutated tumors, and between the KRAS-mutated-only tumor and the KRAS and STK11-co-mutated tumors. Significantly more FOXP3-high TILs were observed in invasive pathological subtypes than in non-invasive ones. CONCLUSION: Comparing TMEs among MPLCs revealed that non-smokers or light smokers and females were unlikely to express PD-L1 regardless of tumor site and confirmed that the EGFR mutations and co-occurring KRAS and STK11 or TP53 mutations were associated with TME. Pathological subtypes may impact the efficacy of immune therapy due to their potential correlations with regulatory T cells.

Can smoking duration alone replace pack-years to predict the risk of smoking-related oncogenic mutations in non-small cell lung cancer? A cross-sectional study in Japan.

OBJECTIVE: To investigate whether smoking duration alone can replace pack-years to predict the risk of oncogenic mutations in non-small cell lung cancer (NSCLC). DESIGN: A cross-sectional study using the baseline dataset from the Japan Molecular Epidemiology for Lung Cancer Study. SETTING: Forty-three medical institutions nationwide in Japan. PARTICIPANTS: From July 2012 to December 2013, 957 patients with newly diagnosed stage I-IIIB NSCLC who underwent surgery were enrolled, and molecular analyses were performed on 876 samples (from 441 ever-smokers and 435 never-smokers). MAIN OUTCOMES MEASURED: We calculated the area under the receiver operating characteristic curve (AUC) values using logistic regression to compare between the predictive values of smoking duration and pack-years for mutational frequencies in the v-Ki-ras2 Kirsten rat sarcoma (KRAS), tumour suppressor p53 (TP53), and epidermal growth factor receptor (EGFR) genes and for cytosine-to-adenine base substitution (C>A). RESULTS: For predicting KRAS mutations, the AUC values for smoking duration and pack-years were 0.746 (95% CI 0.682 to 0.800) and 0.759 (95% CI 0.700 to 0.810), respectively (p=0.058). For predicting KRAS mutations in smokers, the AUC values for smoking duration and pack-years were 0.772 (95% CI 0.697 to 0.833) and 0.787 (95% CI 0.714 to 0.845), respectively (p=0.036). There were no significant differences between the AUC values for smoking duration and pack-years in terms of predicting TP53 and EGFR mutations and C>A. Pack-years was a significantly better predictor of KRAS mutations than smoking duration. CONCLUSION: Smoking duration was not significantly different from pack-years in predicting the likelihood of smoking-related gene mutations. Given the recall bias in obtaining smoking information, smoking duration alone should be considered for further investigation as a simpler alternative to pack-years.

Differences in molecular epidemiology of lung cancer among ethnicities (Asian vs. Caucasian).

BACKGROUND: Differences in carcinogenesis and therapeutic efficacy according to ethnicity have been reported for lung cancer, and understanding differences in genetic mutation profiles among ethnicities is important for interpreting the results of clinical trials, preventing carcinogenesis, and individualizing treatment. However, no studies have focused on differences in mutation profiles among different ethnicities using large-scale genomic analysis data with detailed information on smoking history, the main cause of lung cancer. METHODS: To clarify the differences in genetic mutation profiles between Caucasian and Japanese subjects, we compared data from The Cancer Genome Atlas, which mainly included Caucasians, with results from the Japan Molecular Epidemiology for lung cancer study, which is an epidemiological study only involving Japanese subjects. We divided the participants into four groups according to smoking status and performed comparative analysis by tissue type (lung adenocarcinoma and squamous cell lung cancer). RESULTS: In patients with lung adenocarcinoma, the frequency of EGFR mutations was lower in Caucasian subjects than in Japanese subjects (14.6% vs. 51.1%), whereas the frequencies of mutations in other genes, namely KRAS (32.9% vs. 9.3%), TP53 (45.2% vs. 20.7%), BRAF (9.6% vs. 1.3%), PIK3CA (5.9% vs. 2.6%), KEAP1 (17.8% vs. 0.5%), NF1 (10.9% vs. 0.5%), STK11 (17.8% vs. 0.7%), RBM10 (8.7% vs. 0.1%), and MET (7.8% vs. 0.1%), were higher in Caucasian subjects. Among patients with squamous cell carcinoma, TP53 (81.2% vs. 49.1%), PIK3CA (14.5% vs. 6.8%), KEAP1 (12.7% vs. 0.9%), and NFE2L2 mutations (15.8% vs. 13.6%) were more common in Caucasian subjects. CONCLUSIONS: Ethnicity is an important and complex characteristic that must be recognized and considered, even in the era of precision medicine. We should collaborate to share data for different ethnicities and incorporate them into clinical practice and the design of global clinical studies. Carefully designed molecular epidemiological studies focusing on ethnic differences are warranted.