Detecting acquired V-Raf murine sarcoma viral oncogene homolog B1 V600E mutation associated with osimertinib resistance in epidermal growth factor receptor-mutant lung adenocarcinoma: A case report.

Osimertinib has demonstrated efficacy as the first- and second-line treatment for advanced non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) gene mutations. However, EGFR-mutant NSCLC cells often acquire resistance to osimertinib. V-Raf murine sarcoma viral oncogene homolog B1 (BRAF) mutation (BRAF V600E) was detected in a re-biopsy (LC-SCRUM-TRY testing) of a patient with advanced lung adenocarcinoma who was resistant to osimertinib treatment. Currently, the patient is receiving dabrafenib/trametinib combination therapy and is under observation; a slight shrinking effect of cancer has been observed.

Effect of Tegafur-Uracil in Resected Stage IB Lung Adenocarcinoma According to Presence or Absence of Epidermal Growth Factor Receptor Gene Mutation: A Retrospective Cohort Study.

PURPOSE: Tegafur-uracil (UFT) is the standard postoperative adjuvant therapy for stage IB lung adenocarcinoma (LUAD) in Japan. This study aimed to determine whether UFT is effective in stage IB LUAD with and without epidermal growth factor receptor (EGFR) mutations. METHODS: This retrospective study included 169 patients with stage IB LUAD who underwent complete resection at our department between 2010 and 2021. We investigated the clinicopathological and prognostic impact of EGFR mutations as well as the postoperative use of UFT. RESULTS: EGFR mutation-positive cases tended to show a higher cumulative recurrence rate than EGFR mutation-negative cases (p = 0.081), while overall survival was comparable between the groups (p = 0.238). In the entire cohort, UFT administration was not an independent prognostic factor in the multivariate regression analysis (p = 0.112). According to a stratification analysis, UFT administration was independently associated with favorable overall survival (p = 0.031) in EGFR mutation-negative cases, while it was not associated with recurrence-free survival (p = 0.991) or overall survival (p = 0.398) in EGFR mutation-positive cases. CONCLUSION: UFT administration can improve the prognosis of EGFR mutation-negative LUAD but not EGFR mutation-positive LUAD. Thus, clinical trials of adjuvant-targeted therapy for EGFR mutation-positive stage IB LUAD should also be conducted in Japan.

Identification of Tumor-Suppressive miR-139-3p-Regulated Genes: TRIP13 as a Therapeutic Target in Lung Adenocarcinoma.

Analyses of our microRNA (miRNA) expression signature combined with The Cancer Genome Atlas (TCGA) data revealed that both strands of pre-miR-139 (miR-139-5p, the guide strand, and miR-139-3p, the passenger strand) are significantly downregulated in lung adenocarcinoma (LUAD) clinical specimens. Functional analyses of LUAD cells ectopically expressing miR-139-3p showed significant suppression of their aggressiveness (e.g., cancer cell proliferation, migration, and invasion). The involvement of the passenger strand, miR-139-3p, in LUAD pathogenesis, is an interesting finding contributing to the elucidation of unknown molecular networks in LUAD. Of 1108 genes identified as miR-139-3p targets in LUAD cells, 21 were significantly upregulated in LUAD tissues according to TCGA analysis, and their high expression negatively affected the prognosis of LUAD patients. We focused on thyroid hormone receptor interactor 13 (TRIP13) and investigated its cancer-promoting functions in LUAD cells. Luciferase assays showed that miR-139-3p directly regulated TRIP13. siRNA-mediated TRIP13 knockdown and TRIP13 inhibition by a specific inhibitor (DCZ0415) attenuated the malignant transformation of LUAD cells. Interestingly, when used in combination with anticancer drugs (cisplatin and carboplatin), DCZ0415 exerted synergistic effects on cell proliferation suppression. Identifying the molecular pathways regulated by tumor-suppressive miRNAs (including passenger strands) may aid in the discovery of diagnostic markers and therapeutic targets for LUAD.

Successful Treatment with Osimertinib Based on Therapeutic Drug Monitoring in a Hemodialysis Patient with Non-Small Cell Lung Cancer: A Case Report.

Although osimertinib is a key drug in the treatment of non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutation, the safety in hemodialysis patients has not been established. A 76-year-old man was diagnosed with NSCLC with EGFR deletion mutation in exon 19. After treatment failure with first- and second-generation EGFR tyrosine kinase inhibitors, a T790M mutation was revealed by liquid biopsy. Hemodialysis was started three times a week because chronic renal failure worsened during treatment. Although the subsequent administration of osimertinib (80 mg daily) resulted in a tumor shrinkage and a gradual increase in the plasma concentration of osimertinib, which resulted in grade 3 general fatigue, reducing the dosage of osimertinib decreased its plasma concentration, leading to an improvement in his adverse event. Subsequently, with by adjusting the dosage while periodically measuring the plasma concentration of osimertinib, a stable therapeutic effect was sustained over the long term with no symptoms. Periodic plasma concentration measurements may be indispensable for successful treatment with osimertinib in hemodialysis patients.

The Molecular Pathogenesis of Tumor-Suppressive miR-486-5p and miR-486-3p Target Genes: GINS4 Facilitates Aggressiveness in Lung Adenocarcinoma.

The involvement of passenger strands of miRNAs in the molecular pathogenesis of human cancers is a recent concept in miRNA research, and it will broaden our understanding of the molecular mechanisms of miRNA-mediated cancer. The analysis of our miRNA signature of LUAD revealed that both strands of pre-miR-486 (miR-486-5p and miR-486-3p) were downregulated in LUAD tissues. Ectopic expression of both miRNAs induced cell cycle arrest in LUAD cells, suggesting both strands of miRNAs derived from pre-miR-486 were tumor suppressive. Our in silico analysis showed a total of 99 genes may be under the control of both miRNAs in LUAD cells. Importantly, among these targets, the high expression of seven genes (MKI67, GINS4, RRM2, HELLS, MELK, TIMELESS, and SAPCD2) predicted a poorer prognosis of LUAD patients (p < 0.05). We focused on GINS4, a DNA replication complex GINS protein that plays an essential role in the initiation of DNA replication. Our functional assays showed that GINS4 was directly controlled by both strands of pre-miR-486, and its aberrant expression facilitated the aggressive behavior of LUAD cells. GINS4 is attractive as a therapeutic target for this disease. MiRNA analysis, including passenger strands, will further improve our understanding of the molecular pathogenesis of LUAD.

Minichromosome maintenance proteins in lung adenocarcinoma: Clinical significance and therapeutic targets.

Lung cancer is the most common cause of cancer-related death worldwide, accounting for 1.8 million deaths annually. Analysis of The Cancer Genome Atlas data showed that all members of the minichromosome maintenance (MCM) family (hexamers involved in DNA replication: MCM2-MCM7) were upregulated in lung adenocarcinoma (LUAD) tissues. High expression of MCM4 (P = 0.0032), MCM5 (P = 0.0032), and MCM7 (P = 0.0110) significantly predicted 5-year survival rates in patients with LUAD. Simurosertib (TAK-931) significantly suppressed the proliferation of LUAD cells by inhibiting cell division cycle 7-mediated MCM2 phosphorylation. This finding suggested that MCM2 might be a therapeutic target for LUAD. Moreover, analysis of the epigenetic regulation of MCM2 showed that miR-139-3p, miR-378a-5p, and miR-2110 modulated MCM2 expression in LUAD cells. In patients with LUAD, understanding the role of these miRNAs may improve prognoses.

Immune checkpoint therapy and response biomarkers in non-small-cell lung cancer: Serum NY-ESO-1 and XAGE1 antibody as predictive and monitoring markers.

Immune checkpoint inhibitors (ICI) are key drugs in systemic therapy for advanced non-small-cell lung cancer (NSCLC) and have recently been incorporated into neoadjuvant and adjuvant settings for surgical resection. Currently, ICI combinations with cytotoxic agents are frequently used in clinical practice, although several ICI clinical trials have failed to produce long-term clinical benefits. Unfortunately, clinical benefit is moderate and limited considering physical and financial burden. Therefore, selecting appropriate patients and regimens for ICI therapy is important, and biomarkers are necessary for their selection. Tumor PD-L1 expression is universally used as a biomarker; however, PD-L1 assays show low analytical validity and reproducibility due to the visual-scoring system by pathologists. Recent tumor immunology studies explore that neoantigens derived from somatic mutations and the collaboration between T and B cells efficiently elicit antitumor responses. This suggests that high tumor mutational burden and T-cell infiltration are predictive biomarkers. However, B cells producing antibody (Ab) remain poorly understood and analyzed as biomarkers. We found that NY-ESO-1 and XAGE1 of cancer-testis antigen frequently elicit spontaneous humoral and cellular immune responses in NSCLC. Serum Ab against these antigens were detected in approximately 25% of NSCLC patients and predicted ICI monotherapy responses. In addition, the Ab levels were decreased with tumor shrinkage after ICI therapy. Thus, NY-ESO-1 and XAGE1 Ab are potentially biomarkers predicting and monitoring response to ICI therapy. For clinical applications, a fully-automated assay system measuring the Ab was developed. Here, we review current ICI therapy, tumor immunology, and biomarkers in NSCLC, and discuss the applicability of the serum biomarkers NY-ESO-1 and XAGE1 Ab.

MicroRNA signature of small-cell lung cancer after treatment failure: impact on oncogenic targets by miR-30a-3p control.

Small-cell lung cancer (SCLC) is associated with a high mortality rate and limited treatment efficacy. We created a microRNA (miRNA) expression signature by RNA sequencing using specimens from patients with SCLC who had failed treatment. Forty-nine miRNAs were downregulated in SCLC tissues and were candidate tumor-suppressive miRNAs. In this signature, both guide and passenger strands were downregulated for five miRNAs (miR-30a, miR-34b, miR-34c, miR-223, and miR-4529). Recent studies have revealed that passenger strands of miRNAs are involved in the molecular pathogenesis of human cancer. Although miR-30a-5p (the guide strand) has been shown to be a tumor-suppressive miRNA in various types of cancers, miR-30a-3p (the passenger strand) function is not well characterized in SCLC cells. We investigated the functional significance of miR-30a-3p and oncogenic genes regulated by miR-30a-3p in SCLC cells. Ectopic expression assays showed that miR-30a-3p expression inhibited cell proliferation and induced cell cycle arrest and apoptosis in two SCLC cell lines. Furthermore, in silico database searches and gene expression assays identified 25 genes as putative targets of miR-30a-3p in SCLC cells. Luciferase reporter assays revealed that downstream neighbor of SON (DONSON) was directly regulated by miR-30a-3p in SCLC cells. Knockdown of DONSON induced cell cycle arrest in SCLC cells and DONSON overexpression were detected in SCLC clinical samples. Analyzing the regulatory networks of tumor-suppressive miRNAs may lead to the identification of therapeutic targets in SCLC.

Regulation of Oncogenic Targets by Tumor-Suppressive miR-150-3p in Lung Squamous Cell Carcinoma.

Several recent studies have shown that both strands of certain miRNAs derived from miRNA duplexes are involved in cancer pathogenesis. Our own recent studies revealed that both strands of the miR-150 duplex act as tumor-suppressive miRNAs in lung adenocarcinoma (LUAD) through the targeting of several oncogenes. The aim of the study here was to further investigate the tumor-suppressive roles of miR-150-3p (the passenger strand) in lung squamous cell carcinoma (LUSQ) and its control of cancer-promoting genes in LUSQ cells. The downregulation of miR-150-3p in LUSQ tissues was confirmed by data in The Cancer Genome Atlas (TCGA). The ectopic expression of miR-150-3p attenuated cancer cell aggressive features, e.g., cell cycle arrest, migration and invasive abilities. Our target search strategy successfully identified a total of 49 putative targets that were listed as subjects of miR-150-3p regulation in LUSQ cells. Interestingly, among these targets, 17 genes were categorized as related to the "cell cycle" based on Gene Ontology (GO) classification, namely CENPA, CIT, CCNE1, CCNE2, TIMELESS, BUB1, MCM4, HELLS, SKA3, CDCA2, FANCD2, NUF2, E2F2, SUV39H2, CASC5, ZWILCH and CKAP2). Moreover, we show that the expression of HELLS (helicase, lymphoid specific) is directly controlled by miR-150-3p, and its expression promotes the malignant phenotype of LUSQ cells.

High Incidence of C797S Mutation in Patients With Long Treatment History of EGFR Tyrosine Kinase Inhibitors Including Osimertinib.

INTRODUCTION: Although treatment with osimertinib confers survival benefits in patients with lung cancer with the EGFR T790M mutation, the mechanism of acquired resistance to osimertinib remains poorly understood. We conducted a prospective observational study to identify the mechanism on the basis of repeated tissue biopsies. METHODS: Patients with EGFR-mutated advanced lung cancer with a T790M mutation detected on a tissue biopsy underwent a rebiopsy after developing acquired resistance to osimertinib. Nucleic acids extracted from the biopsy samples were subjected to targeted resequencing (Oncomine Comprehensive Assay), and circulating cell-free DNA (ccfDNA) was analyzed by CAncer Personalized Profiling by deep Sequencing (AVENIO ctDNA Surveillance Kit). RESULTS: Between November 2016 and March 2020, a total of 87 patients were screened. Among them, 44 developed acquired resistance. Of these, 19 samples from rebiopsies and 12 from preosimertinib biopsies were able to be analyzed by an Oncomine Comprehensive Assay. A ccfDNA analysis was performed in 16 patients. Regarding the mechanisms of acquired resistance, structural change in EGFR, namely, C797S, G796S, or L792V, was the most frequent alteration, being observed in 57.9% of the cases. MET gain was observed in 31.6% of the cases, and gains in cell cycle genes were observed in 26.3% of the cases. In addition, we identified GAS6 gain and an ATM mutation in a patient with small-cell transformation and a BRAF V600E mutation in a patient with oligoprogressive disease. CONCLUSIONS: A repeated tissue biopsy and a ccfDNA analysis were useful in analyzing the mechanisms underlying acquired resistance. A long treatment history of EGFR TKIs may result in a high percentage of EGFR structural change.

A Phase II Study of Osimertinib for Radiotherapy-Naive Central Nervous System Metastasis From NSCLC: Results for the T790M Cohort of the OCEAN Study (LOGIK1603/WJOG9116L).

OBJECTIVES: Osimertinib has been reported to be effective against central nervous system (CNS) metastasis from activating EGFR mutation-positive NSCLC. Nevertheless, the true antitumor effects of osimertinib alone for CNS metastasis are unclear because the aforementioned studies included previously irradiated cases, in which tumor shrinkage can occur later owing to the effects of radiotherapy (RT). This study aimed to evaluate the efficacy of osimertinib against RT-naive CNS metastasis from sensitizing EGFR mutation-positive NSCLC. METHODS: The OCEAN study was a two-cohort trial, involving 66 patients (T790M cohort [n = 40] and first-line cohort [n = 26]) with RT-naive CNS metastasis from sensitizing EGFR mutation-positive NSCLC. The patients were treated once daily with 80 mg osimertinib. The primary end point was brain metastasis response rate (BMRR) according to the PAREXEL criteria. In this report, we present the results for the T790M cohort with analysis of drug concentrations and plasma circulating tumor DNA. RESULTS: The median age of the patients was 69 years, and 30% of them were males. Eight patients (20%) were symptomatic, and most had multiple CNS metastases (78%). Among the eligible 39 patients, the BMRR (PAREXEL criteria), median brain metastasis-related progression-free survival (PFS), median overall survival, overall response rate, and median PFS were 66.7% (90% confidence interval: 54.3%-79.1%), 25.2 months, 19.8 months, 40.5%, and 7.1 months, respectively. The BMRR according to the Response Evaluation Criteria in Solid Tumors criteria was 70.0% (n = 20). The brain metastasis-related PFS of patients with EGFR exon 19 deletion was significantly longer than that of exon 21 L858R (median = 31.8 versus 8.3 mo; log-rank p = 0.032). The treatment-related pneumonitis was observed in four patients (10%). On or after day 22, the median trough blood and cerebrospinal fluid concentrations of osimertinib were 568 nM and 4.10 nM, respectively, and those of its metabolite AZ5104 were 68.0 nM and 0.260 nM, respectively. The median blood to cerebrospinal fluid penetration rates of osimertinib and AZ5104 were 0.79% and 0.53%, respectively. The blood trough concentration at day 22 was not correlated with the efficacy of osimertinib against CNS metastasis. Plasma T790M and C797S mutations were detected in 83% and 3% of the patients before treatment, 11% and 3% of the patients on day 22, and 39% and 22% of the patients at the detection of progressive disease, respectively. CONCLUSIONS: This study evaluated the efficacy of osimertinib against RT-naive CNS metastasis from T790M-positive NSCLC. The primary end point was met, and the results revealed the efficacy of osimertinib in patients with CNS metastasis harboring EGFR T790M mutations especially for EGFR-sensitizing mutation of exon 19 deletion.

High-Trough Plasma Concentration of Afatinib Is Associated with Dose Reduction.

Afatinib is used to treat non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutation as a second-generation EGFR-tyrosine kinase inhibitor (TKI). Early prediction of adverse effects based on the pharmacokinetics of afatinib enables support for quality of life (QOL) in patients with no change in efficacy. We examined the pharmacokinetic relationship between trough plasma concentration and adverse effects and evaluated the utility of measuring the trough plasma concentration of afatinib as the first EGFR-TKI treatment for NSCLC in a prospective multicenter study. Twenty-four patients treated with afatinib were enrolled in this study. All blood samples were collected at the trough point, and plasma concentrations were measured using high-performance liquid chromatography-tandem mass spectrometry. Logistic regression analysis for the dose reduction of afatinib was performed, and the receiver operating characteristic (ROC) curve was plotted. Although all patients started afatinib at 40 mg/day, plasma concentrations were variable, and mean and median trough plasma concentrations were 32.9 ng/mL and 32.5 ng/mL in this study, respectively. Minimum and maximum trough plasma concentrations were 10.4 ng/mL and 72.7 ng/mL, respectively. This variability was speculated to involve personal parameters such as laboratory data. However, no patient characteristics or laboratory data examined correlated with the trough plasma concentration of afatinib, except albumin. Albumin showed a weak correlation with plasma concentration (r = 0.60, p = 0.009). The trough plasma concentration of afatinib was significantly associated with the dose reduction of afatinib (p = 0.047). The area under the ROC curve (AUC) for the trough plasma concentration of afatinib was 0.81. The cut-off value was 21.4 ng/mL. The sensitivity and specificity of the cut-off as a risk factor were 0.80 and 0.75. In summary, the trough plasma concentration of afatinib was associated with continued or reduced dosage because of the onset of several adverse effects, and a threshold was seen. Adverse effects not only lower QOL but also hinder continued treatment. Measuring plasma concentrations of afatinib appears valuable to predict adverse effects and continue effective therapy.

The role of comprehensive analysis with circulating tumor DNA in advanced non-small cell lung cancer patients considered for osimertinib treatment.

BACKGROUND: EGFR mutations are good predictive markers of efficacy of EGFR tyrosine kinase inhibitors (EGFR-TKI), but whether comprehensive genomic analysis beyond EGFR itself with circulating tumor DNA (ctDNA) adds further predictive or prognostic value has not been clarified. METHODS: Patients with NSCLC who progressed after treatment with EGFR-TKI, and with EGFR T790 M detected by an approved companion diagnostic test (cobas® ), were treated with osimertinib. Plasma samples were collected before and after treatment. Retrospective comprehensive next-generation sequencing (NGS) of ctDNA was performed with Guardant360® . Correlation between relevant mutations in ctDNA prior to treatment and clinical outcomes, as well as mechanisms of acquired resistance, were analyzed. RESULTS: Among 147 patients tested, 57 patients received osimertinib, with an overall response rate (ORR) of 58%. NGS was successful in 54 of 55 available banked plasma samples; EGFR driver mutations were detected in 43 (80%) and T790 M in 32 (59%). The ORR differed significantly depending on the ratio (T790 M allele fraction [AF])/(sum of variant AF) in ctDNA (p = 0.044). The total number of alterations detected in plasma by NGS was higher in early resistance patients (p = 0.025). T790 M was lost in 32% of patients (6 out of 19) after acquired resistance to osimertinib. One patient with RB1 deletion and copy number gains of EGFR, PIK3CA, and MYC in addition to T790 M, showed rapid progression due to suspected small cell transformation. CONCLUSIONS: NGS of ctDNA could be a promising method for predicting osimertinib efficacy in patients with advanced NSCLC harboring EGFR T790 M.

Molecular Signature of Small Cell Lung Cancer after Treatment Failure: The MCM Complex as Therapeutic Target.

Small cell lung cancer (SCLC) is a highly aggressive cancer, and patients who become refractory to first-line treatment have a poor prognosis. The development of effective treatment regimens is urgently needed. In this study, we identified a gene expression signature of SCLC after treatment failure using SCLC clinical specimens (GEO accession number: GSE162102). A total of 1,136 genes were significantly upregulated in SCLC tissues. These upregulated genes were subjected to KEGG pathway analysis, and "cell cycle", "Fanconi anemia", "alcoholism", "systemic lupus erythematosus", "oocyte meiosis", "homologous recombination", "DNA replication", and "p53 signaling" were identified as the enriched pathways among the genes. We focused on the cell cycle pathway and investigated the clinical significance of four genes associated with this pathway: minichromosome maintenance (MCM) 2, MCM4, MCM6, and MCM7. The overexpression of these MCM genes was confirmed in SCLC clinical specimens. Knockdown assays using siRNAs targeting each of these four MCM genes showed significant attenuation of cancer cell proliferation. Moreover, siRNA-mediated knockdown of each MCM gene enhanced the cisplatin sensitivity of SCLC cells. Our SCLC molecular signature based on SCLC clinical specimens after treatment failure will provide useful information to identify novel molecular targets for this disease.

FAM64A: A Novel Oncogenic Target of Lung Adenocarcinoma Regulated by Both Strands of miR-99a (miR-99a-5p and miR-99a-3p).

Lung adenocarcinoma (LUAD) is the most aggressive cancer and the prognosis of these patients is unfavorable. We revealed that the expression levels of both strands of miR-99a (miR-99a-5p and miR-99a-3p) were significantly suppressed in several cancer tissues. Analyses of large The Cancer Genome Atlas (TCGA) datasets showed that reduced miR-99a-5p or miR-99a-3p expression is associated with worse prognoses in LUAD patients (disease-free survival (DFS): p = 0.1264 and 0.0316; overall survival (OS): p = 0.0176 and 0.0756, respectively). Ectopic expression of these miRNAs attenuated LUAD cell proliferation, suggesting their tumor-suppressive roles. Our in silico analysis revealed 23 putative target genes of pre-miR-99a in LUAD cells. Among these targets, high expressions of 19 genes were associated with worse prognoses in LUAD patients (OS: p < 0.05). Notably, FAM64A was regulated by both miR-99a-5p and miR-99a-3p in LUAD cells, and its aberrant expression was significantly associated with poor prognosis in LUAD patients (OS: p = 0.0175; DFS: p = 0.0276). FAM64A knockdown using siRNAs suggested that elevated FAM64A expression contributes to cancer progression. Aberrant FAM64A expression was detected in LUAD tissues by immunostaining. Taken together, our miRNA-based analysis might be effective for identifying prognostic and therapeutic molecules in LUAD.

A phase II study of Osimertinib for patients with radiotherapy-naïve CNS metastasis of non-small cell lung cancer: treatment rationale and protocol design of the OCEAN study (LOGIK 1603/WJOG 9116L).

BACKGROUND: Patients with activating epidermal growth factor receptor (EGFR) mutations are highly responsive to EGFR-tyrosine kinase inhibitors (TKIs). However, it has been reported that approximately 15-30% of patients treated with EGFR-TKIs experience central nervous system (CNS) progression, and patients with EGFR mutations exhibit a higher incidence of brain metastasis than those without such mutations. The efficacy of osimertinib for treating CNS metastasis has been reported, but its efficacy for CNS metastasis in radiotherapy-naïve patients is unclear. METHODS: In the present prospective two-cohort phase II trial, 65 patients (T790M cohort, 40 patients; first-line cohort, 25 patients) with radiotherapy-naïve CNS metastasis of EGFR mutation-positive non-small cell lung cancer (NSCLC) will be included. Patients will be treated once-daily with osimertinib 80 mg. The primary endpoint is the response rate of brain metastasis as assessed using the PAREXEL criteria. Key secondary endpoints are progression-free survival and the response rate of brain metastasis as assessed using the RECIST criteria. We will exploratorily analyze the relationships of the blood concentration of osimertinib with its efficacy against brain metastasis of NSCLC and the accumulation of osimertinib in cerebrospinal fluid and evaluate tumor-derived DNA from plasma specimens for mutations in EGFR and other genes. Recruitment, which in October 2016, is ongoing. DISCUSSION: Although previous reports revealed the efficacy of osimertinib for CNS metastasis, these reports only involved subgroup analysis, and the efficacy of osimertinib for patients with previously untreated CNS metastasis remains unclear. The OCEAN study is the only trial of osimertinib for patients with untreated brain metastasis of NSCLC. This study should provide novel data about osimertinib. If the results of the OCEAN study are positive, then avoidance of radiotherapy will be recommended to patients harboring EGFR mutations and brain metastasis. TRIAL REGISTRATION: UMIN identifier: UMIN000024218 (date of initial registration: 29 September 2016). jRCT identifier: jRCTs071180017 (date of initial registration: 13 February 2019).

Involvement of Dual Strands of miR-143 (miR-143-5p and miR-143-3p) and Their Target Oncogenes in the Molecular Pathogenesis of Lung Adenocarcinoma.

Our analyses of tumor-suppressive microRNAs (miRNAs) and their target oncogenes have identified novel molecular networks in lung adenocarcinoma (LUAD). Moreover, our recent studies revealed that some passenger strands of miRNAs contribute to cancer cell malignant transformation. Downregulation of both strands of the miR-143 duplex was observed in LUAD clinical specimens. Ectopic expression of these miRNAs suppressed malignant phenotypes in cancer cells, suggesting that these miRNAs have tumor-suppressive activities in LUAD cells. Here, we evaluated miR-143-5p molecular networks in LUAD using genome-wide gene expression and miRNA database analyses. Twenty-two genes were identified as potential miR-143-5p-controlled genes in LUAD cells. Interestingly, the expression of 11 genes (MCM4, RAD51, FAM111B, CLGN, KRT80, GPC1, MTL5, NETO2, FANCA, MTFR1, and TTLL12) was a prognostic factor for the patients with LUAD. Furthermore, knockdown assays using siRNAs showed that downregulation of MCM4 suppressed cell growth, migration, and invasion in LUAD cells. Aberrant expression of MCM4 was confirmed in the clinical specimens of LUAD. Thus, we showed that miR-143-5p and its target genes were involved in the molecular pathogenesis of LUAD. Identification of tumor-suppressive miRNAs and their target oncogenes may be an effective strategy for elucidation of the molecular oncogenic networks of this disease.

Molecular Pathogenesis of Gene Regulation by the miR-150 Duplex: miR-150-3p Regulates TNS4 in Lung Adenocarcinoma.

Based on our miRNA expression signatures, we focused on miR-150-5p (the guide strand) and miR-150-3p (the passenger strand) to investigate their functional significance in lung adenocarcinoma (LUAD). Downregulation of miR-150 duplex was confirmed in LUAD clinical specimens. In vitro assays revealed that ectopic expression of miR-150-5p and miR-150-3p inhibited cancer cell malignancy. We performed genome-wide gene expression analyses and in silico database searches to identify their oncogenic targets in LUAD cells. A total of 41 and 26 genes were identified as miR-150-5p and miR-150-3p targets, respectively, and they were closely involved in LUAD pathogenesis. Among the targets, we investigated the oncogenic roles of tensin 4 (TNS4) because high expression of TNS4 was strongly related to poorer prognosis of LUAD patients (disease-free survival: p = 0.0213 and overall survival: p = 0.0003). Expression of TNS4 was directly regulated by miR-150-3p in LUAD cells. Aberrant expression of TNS4 was detected in LUAD clinical specimens and its aberrant expression increased the aggressiveness of LUAD cells. Furthermore, we identified genes downstream from TNS4 that were associated with critical regulators of genomic stability. Our approach (discovery of anti-tumor miRNAs and their target RNAs for LUAD) will contribute to the elucidation of molecular networks involved in the malignant transformation of LUAD.

Regulation of KIF2A by Antitumor miR-451a Inhibits Cancer Cell Aggressiveness Features in Lung Squamous Cell Carcinoma.

In the human genome, miR-451a is encoded close to the miR-144 on chromosome region 17q11.2. Our previous study showed that both strands of pre-miR-144 acted as antitumor miRNAs and were involved in lung squamous cell carcinoma (LUSQ) pathogenesis. Here, we aimed to investigate the functional significance of miR-451a and to identify its targeting of oncogenic genes in LUSQ cells. Downregulation of miR-451a was confirmed in LUSQ clinical specimens, and low expression of miR-451a was significantly associated with poor prognosis of LUSQ patients (overall survival: p = 0.035, disease-free survival: p = 0.029). Additionally, we showed that ectopic expression of miR-451a significantly blocked cancer cell aggressiveness. In total, 15 putative oncogenic genes were shown to be regulated by miR-451a in LUSQ cells. Among these targets, high kinesin family member 2A (KIF2A) expression was significantly associated with poor prognosis (overall survival: p = 0.043, disease-free survival: p = 0.028). Multivariate analysis showed that KIF2A expression was an independent prognostic factor in patients with LUSQ (hazard ratio = 1.493, p = 0.034). Aberrant KIF2A expression promoted the malignant transformation of this disease. Analytic strategies based on antitumor miRNAs and their target oncogenes are effective tools for identification of novel molecular pathogenesis of LUSQ.

Involvement of dual-strand of the miR-144 duplex and their targets in the pathogenesis of lung squamous cell carcinoma.

The prognosis of patients with advanced-stage lung squamous cell carcinoma (LUSQ) is poor, and effective treatment protocols are limited. Our continuous analyses of antitumor microRNAs (miRNAs) and their oncogenic targets have revealed novel oncogenic pathways in LUSQ. Analyses of our original miRNA expression signatures indicated that both strands of miR-144 (miR-144-5p, the passenger strand; miR-144-3p, the guide strand) showed decreased expression in cancer tissues. Additionally, low expression of miR-144-5p significantly predicted a poor prognosis in patients with LUSQ by The Cancer Genome Atlas database analyses (overall survival, P = 0.026; disease-free survival, P = 0.023). Functional assays revealed that ectopic expression of miR-144-5p and miR-144-3p significantly blocked the malignant abilities of LUSQ cells, eg, cancer cell proliferation, migration, and invasion. In LUSQ cells, 13 and 15 genes were identified as possible oncogenic targets that might be regulated by miR-144-5p and miR-144-3p, respectively. Among these targets, we identified 3 genes (SLC44A5, MARCKS, and NCS1) that might be regulated by both strands of miR-144. Interestingly, high expression of NCS1 predicted a significantly poorer prognosis in patients with LUSQ (overall survival, P = 0.013; disease-free survival, P = 0.048). By multivariate analysis, NCS1 expression was found to be an independent prognostic factor for patients with LUSQ patients. Overexpression of NCS1 was detected in LUSQ clinical specimens, and its aberrant expression enhanced malignant transformation of LUSQ cells. Our approach, involving identification of antitumor miRNAs and their targets, will contribute to improving our understanding of the molecular pathogenesis of LUSQ.