Differential properties of KRAS transversion and transition mutations in non-small cell lung cancer: associations with environmental factors and clinical outcomes.

BACKGROUND: KRAS-mutated non-small cell lung cancer (NSCLC) accounts for 23-35% and 13-20% of all NSCLCs in white patients and East Asians, respectively, and is therefore regarded as a major therapeutic target. However, its epidemiology and clinical characteristics have not been fully elucidated because of its wide variety of mutational subtypes. Here, we focused on two distinct base substitution types: transversion mutations and transition mutations, as well as their association with environmental factors and clinical outcome. METHODS: Dataset from the Japan Molecular Epidemiology Study, which is a prospective, multicenter, and molecular study epidemiology cohort study involving 957 NSCLC patients who underwent surgery, was used for this study. Questionnaire-based detailed information on clinical background and lifestyles was also used to assess their association with mutational subtypes. Somatic mutations in 72 cancer-related genes were analyzed by next-generation sequencing, and KRAS mutations were classified into three categories: transversions (G > C or G > T; G12A, G12C, G12R, G12V), transitions (G > A; G12D, G12S, G13D), and wild-type (WT). Clinical correlations between these subtypes have been investigated, and recurrence-free survival (RFS) and overall survival (OS) were evaluated. RESULTS: Of the 957 patients, KRAS mutations were detected in 80 (8.4%). Of these, 61 were transversions and 19 were transitions mutations. Both pack-years of smoking and smoking duration had significant positive correlation with the occurrence of transversion mutations (p = 0.03 and < 0.01, respectively). Notably, transitions showed an inverse correlation with vegetable intake (p = 0.01). Patients with KRAS transitions had the shortest RFS and OS compared to KRAS transversions and WT. Multivariate analysis revealed that KRAS transitions, along with age and stage, were significant predictors of shorter RFS and OS (HR 2.15, p = 0.01; and HR 2.84, p < 0.01, respectively). CONCLUSIONS: Smoking exposure positively correlated with transversions occurrence in a dose-dependent manner. However, vegetable intake negatively correlated with transitions. Overall, KRAS transition mutations are significantly poor prognostic factors among resected NSCLC patients.

Prognostic impact of pretreatment T790M mutation on outcomes for patients with resected, EGFR-mutated, non-small cell lung cancer.

BACKGROUND: Many previous studies have demonstrated that minor-frequency pretreatment T790M mutation (preT790M) could be detected by ultrasensitive methods in a considerable number of treatment-naïve, epidermal growth factor receptor (EGFR)-mutated, non-small cell lung cancer (NSCLC) cases. However, the impact of preT790M in resected cases on prognosis remains unclear. METHODS: We previously reported that preT790M could be detected in 298 (79.9%) of 373 surgically resected, EGFR-mutated NSCLC patients. Therefore, we investigated the impact of preT790M on recurrence-free survival (RFS) and overall survival (OS) in this cohort by multivariate analysis. All patients were enrolled from July 2012 to December 2013, with follow-up until November 30, 2017. RESULTS: The median follow-up time was 48.6 months. Using a cutoff value of the median preT790M allele frequency, the high-preT790M group (n = 151) had significantly shorter RFS (hazard ratio [HR] = 1.51, 95% confidence interval [CI]: 1.01-2.25, P = 0.045) and a tendency for a shorter OS (HR = 1.87, 95% CI: 0.99-3.55, P = 0.055) than the low-preT790M group (n = 222). On multivariate analysis, higher preT790M was independently associated with shorter RFS (high vs low, HR = 1.56, 95% CI: 1.03-2.36, P = 0.035), irrespective of advanced stage, older age, and male sex, and was also associated with shorter OS (high vs low, HR = 2.16, 95% CI: 1.11-4.20, P = 0.024) irrespective of advanced stage, older age, EGFR mutation subtype, and history of adjuvant chemotherapy. CONCLUSIONS: Minor-frequency, especially high-abundance of, preT790M was an independent factor associated with a poor prognosis in patients with surgically resected, EGFR-mutated NSCLC.

Prospective Observational Study of Treatment Resistance-related Gene Screening Using Plasma Circulating Tumor DNA in Third-generation EGFR-TKI Osimertinib Therapy (Elucidator).

BACKGROUND: Osimertinib is a third-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) that potently and selectively inhibits EGFR activating and EGFR T790M resistance mutations. Osimertinib was found to be more effective than first-generation EGFR-TKIs in patients with previously untreated advanced non-small-cell lung cancer (NSCLC) harboring EGFR-positive mutations in a prior phase III trial. Osimertinib is, therefore, one of the most important standard therapies for EGFR mutation-positive patients. However, there are few reports about osimertinib resistance mechanisms in first-line EGFR-TKI therapy. Understanding first-line osimertinib resistance mechanisms is essential for future therapeutic strategies in patients with NSCLC with EGFR-positive mutations. To clarify the resistance mechanisms of first-line osimertinib, we proposed to analyze circulating tumor (ct) deoxyribonucleic acid (DNA) by the ultra-sensitive next-generation sequencing method. PATIENTS AND METHODS: We aim to collect ctDNA samples from patients with the following key inclusion criteria: histologically or cytologically proven NSCLC, activating EGFR mutation-positive, planned treatment with first-line osimertinib, and written informed consent. Patients with comorbidities, who are deemed unsuitable for participation by an attending physician, would be excluded. We plan to enroll 180 cases and estimate a final analysis of 120 cases following registration and 2-year observation. ctDNA samples are collected at osimertinib treatment initiation, 3 and 12 months later, and disease progression. The key primary endpoint is to clarify the incidence and ratio of osimertinib resistance. The key secondary endpoint is to examine how the quantity of osimertinib resistance-associated mutations detected in ctDNA at treatment initiation influences disease progression.

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.

A Multivariable Regression Model-based Nomogram for Estimating the Overall Survival of Patients Previously Treated With Nivolumab for Advanced Non-small-cell Lung Cancer.

AIM: Although nivolumab improves progression-free (PFS) and overall (OS) survival of patients previously treated for metastatic non-small-cell lung cancer (NSCLC), approximately 50% of treated patients experience disease progression within 3 months. As predictive biomarkers of response are not yet established, development of biomarkers to predict longer PFS and OS of patients treated with nivolumab is crucial. Therefore, we analyzed the impact of predictive markers of response to nivolumab and quantified the impact of each factor using nomograms. PATIENTS AND METHODS: Clinical data at nivolumab commencement were retrospectively collected from 201 patients treated with nivolumab between December 2015 and July 2016. Immunohistochemistry for programmed cell death ligand 1 (PD-L1) was performed using two assay systems (22C3 and 28-8). OS was calculated from nivolumab treatment initiation. Multivariate Cox regression analysis was conducted to identify independent predictors of OS. A nomogram was constructed to estimate OS. RESULTS: The median patient age was 68 years (135 males). Thirty-nine patients had driver mutations (epidermal growth factor receptor mutations and anaplastic lymphoma kinase rearrangement). In 22C3 and 28-8 immunostaining assays, 36.3% and 36.8% patients had PD-L1-negative cells, 17.4% and 14.4% had 1-49% PD-L1-positive cells, 11.9% and 14.9% had ≥50% PD-L1-positive cells, and 34.3% and 33.8% had unknown PD-L1 status, respectively. Kendall's rank correlation coefficient between the staining assays was 0.8414. The median OS of the whole patient cohort was 12.27 months [95% confidence interval (CI)=10.87-15.6]. Performance status ≥2 [hazard ratio (HR)=2.15, 95% CI=1.35-3.42, p=0.001) and high baseline lactate dehydrogenase (HR=1.15, 95% CI=1.05-1.26, p=0.004] were independent predictors of shorter OS. There was no significant correlation between PD-L1 status and OS. We constructed a nomogram to estimate the OS of patients previously treated with nivolumab. CONCLUSION: The multivariate analysis-based nomogram might be useful to estimate the OS of patients previously treated with nivolumab for advanced NSCLC.

Impact of somatic mutations on prognosis in resected non-small-cell lung cancer: The Japan Molecular Epidemiology for lung cancer study.

BACKGROUND: To report the follow up data and clinical outcomes of the JME study (UMIN 000008177), a prospective, multicenter, molecular epidemiology examination of 876 surgically resected non-small-cell lung cancer (NSCLC) cases, and the impact of somatic mutations (72 cancer-associated genes) on recurrence-free survival (RFS) and overall survival (OS). METHODS: Patients were enrolled between July 2012 and December 2013, with follow up to 30th November 2017. A Cox proportional hazards model was used to assess the impact of gene mutations on RFS and OS, considering sex, smoking history, age, stage, histology, EGFR, KRAS, TP53, and number of coexisting mutations. RESULTS: Of 876 patients, 172 had ≥2 somatic mutations. Median follow-up was 48.4 months. On multivariate analysis, number of coexisting mutations (≥2 vs 0 or 1, HR = 2.012, 95% CI: 1.488-2.695), age (≥70 vs <70 years, HR = 1.583, 95% CI: 1.229-2.049), gender (male vs female, HR = 1.503, 95% CI: 1.045-2.170) and pathological stage (II vs I, HR = 3.386, 95% CI: 2.447-4.646; ≥III vs I, HR = 6.307, 95% CI: 4.680-8.476) were significantly associated with RFS, while EGFR mutation (yes vs no, HR = 0.482, 95% CI: 0.309-0.736), number of coexisting mutations (≥2 vs 0 or 1, HR = 1.695, 95% CI: 1.143-2.467), age (≥70 vs <70 years, HR = 1.932, 95% CI: 1.385-2.726), and pathological stage (II vs I, HR = 2.209, 95% CI: 1.431-3.347; ≥III vs I, HR = 5.286, 95% CI: 3.682-7.566) were also significant for OS. CONCLUSION: A smaller number of coexisting mutations, earlier stage, and younger age were associated with longer RFS and OS, while EGFR mutations were significantly associated with improved OS.

Chemotherapy versus erlotinib as second-line treatment in patients with advanced non-small cell lung cancer and wild-type epidermal growth factor receptor: an individual patient data (IPD) analysis.

The efficacy of second-line treatment in patients with epidermal growth factor receptor (EGFR) wild-type tumours is still debatable. We assessed the efficacy of a standard second-line chemotherapy compared with erlotinib in an individual patient data approach for meta-analysis. The primary endpoint was overall survival (OS), and secondary endpoint was progression-free survival (PFS). Both were compared by log-rank test. The 'restricted mean survival time' (RMST) was estimated in each study and the difference in mean survival time up to the last available time point was calculated. The Cox proportional hazards model was used on survival analyses to provide HRs, to adjust for confounding variables and to test possible interaction with selected factors. Three randomised trials comparing chemotherapy versus erlotinib were analysed, including 587 randomised patients. Overall, 74% of patients included in the original trials were considered. 464 deaths and 570 progressions or deaths were observed. Compared with erlotinib, chemotherapy was associated to a decreased risk of progression (29%; HR: 0.71, 95% CI: 0.60 to 0.84, p< 0.0001;) but with no statistical significant reduction in OS (HR: 0.89, 95% CI: 0.74 to 1.06; p<0.20). No heterogeneity was found in both analyses. Patients treated with chemotherapy gained an absolute 1.5 and 1.6 months, respectively, in PFS and lifetime (RMST 95% CI: PFS 0.49 to 2.44; OS 95% CI: -1.04 to 4.25). These results showed that patients without a constitutively activated EGFR had better PFS with chemotherapy rather than with erlotinib while no statistical difference was observed in OS.

Improvement of Mycobacterium abscessus Pulmonary Disease after Nivolumab Administration in a Patient with Advanced Non-small Cell Lung Cancer.

Nivolumab has become the standard second-line chemotherapy for non-small cell lung cancer. A 73-year-old man with stage IV non-small cell lung cancer received 6 cycles of chemotherapy with nab-paclitaxel/carboplatin/bevacizumab followed by 11 cycles of nab-paclitaxel/bevacizumab; however, treatment was stopped due to pneumothorax. One year after therapy started, a nodule appeared in the left upper lung and increased in size. Mycobacterium abscessus subsp. massiliense disease was diagnosed by a sputum analysis. After short antibiotic treatment, nivolumab was administered. Two months after nivolumab treatment, the nodule improved along with a good tumour response. The effectiveness of nivolumab for chronic infectious diseases, such as M. abscessus disease, should be investigated.

Clinical Characteristics of Liver Metastasis in Nivolumab-treated Patients with Non-small Cell Lung Cancer.

BACKGROUND: Recent studies have revealed that liver metastasis is associated with poor outcomes after treatment using immune checkpoint inhibitors, although the cause remains unclear. PATIENTS AND METHODS: We retrospectively identified 201 patients at three Japanese Centers who received nivolumab for advanced non-small cell lung cancer between December 2015 and July 2016. The patients' baseline clinical characteristics and subsequent outcomes were compared according to liver metastasis status. RESULTS: Liver metastasis was associated with inferior progression-free survival (PFS) and a lower response rate. Additionally, liver metastasis was significantly associated with younger age, poorer Eastern Cooperative Oncology Group performance status (ECOG PS), and more metastatic sites. Multivariate analyses revealed that poor PFS was independently associated with poor baseline ECOG PS (p=0.039) and high number of metastatic sites (p=0.007), although liver metastasis (p=0.2) was not. CONCLUSION: Baseline clinical characteristics were a strong predictor of outcome in nivolumab-treated patients with liver metastasis.

Association Between Imaging Findings of Airway Obstruction Adjacent to Lung Tumors and the Onset of Interstitial Lung Disease After Nivolumab.

BACKGROUND: Compared to conventional cytotoxic chemotherapy, immune checkpoint inhibitors have shown a significant efficacy in the treatment of lung cancer. Although interstitial lung disease (ILD) is an important adverse event in immunotherapy, risk factors for ILD remain unclear. PATIENTS AND METHODS: In this multicenter cohort study (UMIN000025908), 201 patients who were treated with nivolumab were retrospectively reviewed. Associations between the incidence of ILD and patient characteristics were evaluated. ILD grade and progression-free survival were analyzed according to the presence or absence of imaging findings of airway obstruction adjacent to lung tumors (IAOT). RESULTS: In the multivariate analysis, the odds ratio (OR) of ILD for patients with a history of radiation pneumonitis or IAOT was 3.96 (p=0.012) and 6.59 (p=0.004), respectively. ILD occurred in six (37.5%) out of 16 patients with IAOT and 19 (10.3%) out of 185 patients without IAOT. Three out of the six patients with ILD and IAOT had ILD of grade 4 or more. The median progression-free survival of patients with and without IAOT was 0.9 and 3.2 months, respectively (p<0.001). CONCLUSION: IAOT was strongly associated with the occurrence of ILD after therapy with nivolumab.

Metastatic site as a predictor of nivolumab efficacy in patients with advanced non-small cell lung cancer: A retrospective multicenter trial.

PURPOSE: To conduct a retrospective multicenter trial to determine the significance of metastatic site as a predictor of nivolumab efficacy in patients with advanced non-small cell lung cancer. METHODS: This study was conducted across three medical centers in Japan. We retrospectively reviewed all patients who commenced nivolumab treatment at these centers between December 17, 2015 and July 31, 2016. Clinical data were collected, including age, sex, smoking status, Eastern Cooperative Oncology Group performance status, and metastatic site (lymph nodes, liver, brain, bone, lungs [intrapulmonary metastasis], and malignant pleural effusion) at the time of commencing nivolumab treatment. Patients were followed-up until March 31, 2017. RESULTS: Two hundred and one patients were enrolled. The median age at the time of commencing nivolumab treatment was 68 (range, 27-87) years. One hundred and thirty-five patients were male, 157 patients had a history of smoking, 153 patients had a performance status of 0-1, and 42 patients had squamous cell carcinoma. The median progression-free survival of all patients was 2.5 months. In the univariate analysis, a performance status of ≥2 (hazard ratio [HR]: 1.89, 95.0% confidence interval [CI]: 1.33-2.69; p < 0.001) and liver (HR: 2.09, 95.0% CI: 1.35-3.25; p < 0.001) and lung (HR: 1.57, 95.0% CI: 1.14-2.16; p < 0.01) metastases correlated with a significantly shorter progression-free survival in nivolumab-treated patients. In the multivariate analysis, a performance status of ≥2 (HR: 1.54, 95.0% CI: 1.05-2.25; p < 0.05) and liver (HR: 1.90, 95.0% CI: 1.21-2.98; p < 0.01) and lung (HR: 1.41, 95.0% CI: 1.00-1.99; p < 0.05) metastases were independently correlated with a significantly shorter progression-free survival in nivolumab-treated patients. CONCLUSION: Liver and lung metastases and a poor performance status are independent predictors of nivolumab efficacy in patients with advanced non-small cell lung cancer.

Pretreatment advanced lung cancer inflammation index (ALI) for predicting early progression in nivolumab-treated patients with advanced non-small cell lung cancer.

Programmed death-ligand 1 (PD-L1) expression status is inadequate for indicating nivolumab in patients with non-small cell lung cancer (NSCLC). Because the baseline advanced lung cancer inflammation index (ALI) is reportedly associated with patient outcomes, we investigated whether the pretreatment ALI is prognostic in NSCLC patients treated with nivolumab. We retrospectively reviewed the medical records of all patients treated with nivolumab for advanced NSCLC between December 2015 and May 2016 at three Japanese institutes. Multivariate logistic regression and Cox proportional hazards models were used to assess the impact of the pretreatment ALI (and other inflammation-related parameters) on progression-free survival (PFS) and early progression (i.e., within 8 weeks after starting nivolumab). A total of 201 patients were analyzed; their median age was 68 years (range, 27-87 years), 67% were men, and 24% had an Eastern Cooperative Oncology Group (ECOG) performance status of 2 or higher. An ECOG performance status ≥2, serum albumin <3.7 g/dL, neutrophil-to-lymphocyte ratio ≥4, and ALI <18 were significantly associated with poor PFS and early progression on univariate analysis. Multivariate analyses revealed that pretreatment ALI <18 was independently associated with inferior PFS (median, 1.4 vs. 3.7 months, P < 0.001) and a higher likelihood of early progression (odds ratio, 2.76; 95% confidence interval 1.44-5.34; P = 0.002). The pretreatment ALI was found to be a significant independent predictor of early progression in patients with advanced NSCLC receiving nivolumab, and may help identify patients likely to benefit from continued nivolumab treatment in routine clinical practice.

The Association Between Chemotherapy Immediately Before Nivolumab and Outcomes Thereafter.

BACKGROUND/AIM: We investigated whether the efficacy and type of pre-nivolumab chemotherapy influence outcomes in non-small cell lung cancer patients following nivolumab treatment. PATIENTS AND METHODS: In this multicenter study, 199 patients treated with nivolumab were retrospectively reviewed. We analyzed the relationships between the clinical response to nivolumab and to chemotherapy administered immediately beforehand. RESULTS: Patients who achieved objective responses to pretreatments showed higher disease control rates with nivolumab than patients who did not (64% vs. 47%, p=0.03), as did those who achieved disease control with pretreatments (62% vs. 35%, p<0.001). Bevacizumab-pretreated patients tended to show better objective response rates with nivolumab (27% vs. 13%, p=0.06); the objective response rate to nivolumab was significantly higher in bevacizumab-pretreated patients who showed clinical responses (42% vs. 9.1%, p=0.02). CONCLUSION: Achievement of a clinical response to chemotherapy immediately before nivolumab, particularly when combined with bevacizumab, increases the likelihood of disease control post-nivolumab.

Correlation of Radiation Pneumonitis History Before Nivolumab with Onset of Interstitial Lung Disease and Progression-free Survival of Patients with Pre-treated Advanced Non-small Cell Lung Cancer.

BACKGROUND/AIM: Nivolumab has a promising efficacy for patients with non-small-cell lung cancer (NSCLC) as second-line or later treatment, and after radiotherapy as abscopal effect. However, the effects of radiation pneumonitis history before nivolumab have not been clarified. Therefore, we retrospectively analyzed the correlation of a history of radiation pneumonitis before nivolumab with onset of interstitial lung disease (ILD) and progression-free survival (PFS) after nivolumab treatment in patients with previously treated NSCLC. PATIENTS AND METHODS: A total of 201 patients treated with nivolumab were retrospectively reviewed. We collected clinical data of patients at the time of starting nivolumab and we evaluated ILD incidence and PFS in relation to patient characteristics, including radiation pneumonitis history. RESULTS: The median age was 68 years; 135 patients were men, 157 had a smoking history, and 153 had performance status of 0 or 1. Thirty-four patients experienced radiation pneumonitis before nivolumab, and 50 patients received radiotherapy to the chest (31 patients received curative radiotherapy). The overall median PFS was 2.8 months and the overall ILD rate was 12.4%. Higher ILD incidence was observed in the group with a history of radiation pneumonitis (26.5%) compared to the group without radiation pneumonitis (9.6%). The median PFS was 3.6 and 2.3 months, respectively. On multivariate analysis, a history of radiation pneumonitis was also significantly correlated with good PFS (p=0.023). CONCLUSION: Although increasing the risk of ILD, a history of radiation pneumonitis before nivolumab also contributes to the prolongation of PFS after nivolumab.

Cerebrospinal Fluid Penetration Rate and Efficacy of Afatinib in Patients with EGFR Mutation-positive Non-small Cell Lung Cancer with Leptomeningeal Carcinomatosis: A Multicenter Prospective Study.

BACKGROUND: Afatinib is an effective first-line treatment for epidermal growth factor receptor (EGFR) mutation-positive advanced non-small cell lung cancer (NSCLC). However, few reports have addressed the influence of cerebrospinal fluid (CSF) penetration rate on the efficacy of afatinib in patients with central nervous system metastases. Therefore, we conducted a prospective multicenter trial to evaluate the CSF penetration rate and efficacy of afatinib in patients with EGFR mutation-positive NSCLC with leptomeningeal carcinomatosis. PATIENTS AND METHODS: Eleven patients with histologically-proven EGFR mutation-positive NSCLC with leptomeningeal carcinomatosis were enrolled in the study between April 2014 and November 2015. They were treated with afatinib (40 mg/day), and blood and CSF levels of afatinib were analyzed on day 8. The primary endpoint was CSF penetration rate. Secondary endpoints included the objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). RESULTS: The median age of patients was 66 years. Five patients harbored an exon 19 deletion, three harbored a p.L858R point mutation, and three harbored an uncommon exon 18 mutation. The levels of afatinib in blood and CSF (mean±SD) were 233.26±195.40 nM and 3.16±1.95 nM, respectively. The CSF penetration rate was 2.45±2.91%. The ORR was 27.3% (three out of 11 patients), and two out of these three responders had uncommon EGFR mutations. The median PFS and OS were 2.0 and 3.8 months, respectively. CONCLUSION: The median CSF penetration rate of afatinib was higher than previously reported. Afatinib was effective against leptomeningeal carcinomatosis particularly in patients with NSCLC harboring uncommon EGFR mutations. The criteria for selecting a specific EGFR tyrosine kinase inhibitor for therapy of NSCLC should include its ability to penetrate CSF and its efficacy against specific mutation types.

Multiplex Ultrasensitive Genotyping of Patients with Non-Small Cell Lung Cancer for Epidermal Growth Factor Receptor (EGFR) Mutations by Means of Picodroplet Digital PCR.

Epidermal growth factor receptor (EGFR) mutations have been used as the strongest predictor of effectiveness of treatment with EGFR tyrosine kinase inhibitors (TKIs). Three most common EGFR mutations (L858R, exon 19 deletion, and T790M) are known to be major selection markers for EGFR-TKIs therapy. Here, we developed a multiplex picodroplet digital PCR (ddPCR) assay to detect 3 common EGFR mutations in 1 reaction. Serial-dilution experiments with genomic DNA harboring EGFR mutations revealed linear performance, with analytical sensitivity ~0.01% for each mutation. All 33 EGFR-activating mutations detected in formalin-fixed paraffin-embedded (FFPE) tissue samples by the conventional method were also detected by this multiplex assay. Owing to the higher sensitivity, an additional mutation (T790M; including an ultra-low-level mutation, <0.1%) was detected in the same reaction. Regression analysis of the duplex assay and multiplex assay showed a correlation coefficient (R2) of 0.9986 for L858R, 0.9844 for an exon 19 deletion, and 0.9959 for T790M. Using ddPCR, we designed a multiplex ultrasensitive genotyping platform for 3 common EGFR mutations. Results of this proof-of-principle study on clinical samples indicate clinical utility of multiplex ddPCR for screening for multiple EGFR mutations concurrently with an ultra-rare pretreatment mutation (T790M).

Prospective Analysis of Oncogenic Driver Mutations and Environmental Factors: Japan Molecular Epidemiology for Lung Cancer Study.

PURPOSE: Oncogenic driver mutations are critical for lung cancer development and serve as therapeutic targets. However, their associations with environmental factors are not fully understood. We aimed to elucidate the relationship between tumor developmental biology and exposure to environmental factors. PATIENTS AND METHODS: This was a prospective, multicenter, molecular epidemiology study. Eligible patients were those with newly diagnosed stages I to IIIB non-small-cell lung cancer (NSCLC) who underwent surgery. The tumors were examined for somatic mutations in 72 cancer-associated genes by targeted deep sequencing, estrogen receptor ß (ERß) expression using immunohistochemical staining, and infection with any of 37 types of human papillomavirus (HPV) using a polymerase chain reaction-based microarray system. Detailed information on patient demographics and environmental factors was obtained from a comprehensive questionnaire. RESULTS: From July 2012 to December 2013, 957 patients were enrolled, and molecular analyses were performed on 876 samples (from 441 ever- and 435 never-smokers). Oncogenic driver mutations in P53 and KRAS increased proportionally with smoking status, whereas mutations in EGFR and SMAD4 decreased. KRAS mutations in smokers and SMAD4 mutations were observed more frequently in proportion to body mass index. TP53 and NFE2L2 mutations were observed more frequently in advanced NSCLC stages. As for never-smokers, no environmental factors were significantly associated with mutational changes. EGFR mutations and TP53 mutations were observed more frequently in women and in men, respectively. Mutations in these two genes were also potentially associated with ERß expression. Only three patients (0.3%) were HPV positive. CONCLUSION: The mutational spectrum is associated with smoking, body mass index, and other environmental factors, as well as with ERß expression. Little association was observed between HPV and NSCLC.

Epidermal growth factor receptor tyrosine kinase inhibitors in previously treated advanced non-small-cell lung cancer with wild-type EGFR.

INTRODUCTION: While epidermal growth factor receptor (EGFR) - tyrosine kinase inhibitors (TKIs) lead to longer progression-free survival (PFS) when compared with conventional chemotherapy in non-small-cell lung cancer (NSCLC) harboring activating EGFR mutations, the role of EGFR-TKI remains unclear in EGFR-wild-type (WT) NSCLC. AREAS COVERED: This article reviews selected data from randomized trials regarding the use of TKIs in EGFR-WT NSCLC. Nine randomized phase III trials have compared EGFR-TKI with chemotherapy in NSCLC patients in a second or later line setting. Two of these trials, TAILOR and DELTA, which were designed to investigate treatment benefits according to EGFR genotype, demonstrated that docetaxel chemotherapy displayed significantly better in progression-free survival (PFS) when compared with the EGFR-TKI erlotinib. Biomarkers to predict clinical benefits of the drug against EGFR WT tumor, and the efficacy of combination regimens using erlotinib or single-use afatinib against tumors are also covered in this article. EXPERT OPINION: Considering the modest benefits of erlotinib for EGFR-WT tumors, future studies are warranted, including the exploration of useful biomarkers and new treatment strategies for EGFT-TKI use, as well as the development of more sensitive EGFR mutation tests.

Molecular Epidemiological Study on Passive Smoking and Estrogen Receptor Expression in Never-smokers with Non-small Cell Lung Cancer.

Background: Although sex hormones are thought to play an important role in the carcinogenesis of non-small cell lung cancer (NSCLC) in never-smokers, the causative mechanism remains unknown. Passive smoking (PS) is common among East Asian women and has been suggested to be a potential cause of the disease. Methods: We systematically evaluated the expression of estrogen receptor (ER), the prevalence of PS, and genetic mutations using tumor samples from a prospectively registered cohort of never-smokers with lung cancer. The study enrolled 92 never-smokers with NSCLC. Expression of ERa, ERP, and progesterone receptor (PR) was examined via immunohistochemical staining (IHC). Detailed PS information was obtained through a standardized questionnaire. The cumulative dose of PS (CPS) was evaluated as a sum of the number of exposure years at home and/or in the work place. Results: Nuclear expression of ERa, ERP, and PR was detected in 0, 14, and 3 cases, respectively. ERP was more frequently overexpressed in earlier stage cancer (p=0.043). Ninety patients (97.9%) had a PS history, and the median CPS was 47.5 years (range, 0-103 years). There was no significant correlation between the amount of PS -and ERP expression (p=0.101). Twelve patients (85.7%) had Epidermal growth factor receptor ,EGFR) mutations in 14 .tumors expressing ERP, and a trend towards an association between ERP expression and EGFR mutations (p =0.067) was -observed. Conclusions: Nuclear expression of ERP was more frequently observed in early stage NSCLC in never-smokers.

Ultra-Sensitive Detection of the Pretreatment EGFR T790M Mutation in Non-Small Cell Lung Cancer Patients with an EGFR-Activating Mutation Using Droplet Digital PCR.

PURPOSE: The resistance to the EGFR tyrosine kinase inhibitors (TKI) is a major concern in non-small cell lung cancer (NSCLC) treatment. T790M mutation in EGFR accounts for nearly 50% of the acquired resistance to EGFR-TKIs. Earlier studies suggested that T790M mutation was also detected in TKI-naïve NSCLCs in a small cohort. Here, we use an ultra-sensitive droplet digital PCR (ddPCR) technique to address the incidence and clinical significance of pretreatment T790M in a larger cohort. EXPERIMENTAL DESIGN: ddPCR was established as follows: wild-type or T790M mutation-containing DNA fragments were cloned into plasmids. Candidate threshold was identified using wild-type plasmid, normal human genomic DNA, and human A549 cell line DNA, which expresses wild type. Surgically resected tumor tissues from 373 NSCLC patients with EGFR-activating mutations were then examined for the presence of T790M using ddPCR. RESULTS: Our data revealed a linear performance for this ddPCR method (R(2) = 0.998) with an analytical sensitivity of approximately 0.001%. The overall incidence of the pretreatment T790M mutation was 79.9% (298/373), and the frequency ranged from 0.009% to 26.9%. The T790M mutation was detected more frequently in patients with a larger tumor size (P = 0.019) and those with common EGFR-activating mutations (P = 0.022), as compared with the others. CONCLUSIONS: The ultra-sensitive ddPCR assay revealed that pretreatment T790M was found in the majority of NSCLC patients with EGFR-activating mutations. ddPCR should be utilized for detailed assessment of the impact of the low frequency pretreatment T790M mutation on treatment with EGFR-TKIs.