Published papers

BACKGROUND: Delta-like protein 3 (DLL3) is a Notch ligand that has an important role in the tumorigenesis of small cell lung cancer (SCLC). Recently, rovalpituzumab tesirine (Rova-T), a DLL3-targeted antibody-drug conjugate, has been developed for treating SCLC. DLL3 is a transcriptional target of the achaete-scute homolog-1 (ASCL1) transcription factor, which is involved in pulmonary neuroendocrine cell development. However, the relationship between DLL3 and/or ASCL1 expression and the clinical features of SCLC remains unknown, especially for early-stage resected SCLC. This study aimed to investigate the expression of DLL3 and ASCL1 in resected SCLC samples using immunohistochemical analysis. MATERIALS AND METHODS: We collected 95 surgically resected SCLC samples, which were formalin fixed and paraffin embedded. Immunohistochemistry staining was performed to investigate the correlation between the expression of either DLL3 or ASCL1 and clinicopathological features of study patients. RESULTS: Seventy-seven (83%) of 93 immunohistochemically evaluable samples were positive for DLL3 (expression in ≥1% of tumor cells), and DLL3-high expression (≥75%) was observed in 44 samples (47%). Sixty-one (64%) of 95 samples were positive for ASCL1 (expression in ≥5% of tumor cells). A positive correlation was observed between DLL3 and ASCL1 expression. DLL3 and ASCL1 expression were not associated with survival in SCLC patients. DLL3 was more prevalent in patients with advanced clinical disease. CONCLUSION: DLL3 and ASCL1 were highly expressed in patients with surgically resected SCLC. DLL3 and ASCL1 may be targets for the treatment of SCLC. IMPLICATIONS FOR PRACTICE: This article examines the relationship between delta-like protein 3 (DLL3) and achaete-scute homolog-1 (ASCL1) protein expression with the clinical features of 95 surgically resected small cell lung cancer (SCLC). DLL3 is attracting attention because rovalpituzumab tesirine (Rova-T), a DLL3-targeted antibody-drug conjugate, was developed recently. DLL3 and ASCL1 were highly expressed in patients with surgically resected SCLC. DLL3 and ASCL1 may be targets for the treatment of early-stage SCLC, including with Rova-T.

Solitary fibrous tumor/hemangiopericytoma (SFT/HPC) is a mesenchymal tumor that can affect virtually any region of the body. SFT/HPC of the thoracic cavity and soft tissue has been histologically considered a single biological entity termed SFT; in fact, NAB2-STAT6 gene fusion was recently identified in both diseases. In contrast, meningeal SFT and HPC still need to be investigated in detail with regard to gene fusion variants. The aim of this study was to verify the frequency of NAB2-STAT6 fusion and the relationship between fusion variants and clinicopathologic findings of SFT/HPC, especially meningeal SFT/HPC. We examined the NAB2-STAT6 fusion by reverse transcription polymerase chain reaction with 4 cases of meningeal SFT and 13 cases of meningeal HPC. NAB2-STAT6 fusion transcripts were identified in 12 of 17 cases, including NAB2ex6-STAT6ex17 (4/17, 24%), NAB2ex6-STAT6ex16 and NAB2ex4-STAT6ex2 (3/17, 18%, respectively), and NAB2ex5-STAT6ex16 (2/17, 12%). Three cases showed a pseudopapillary pattern, and 2 of them carried NAB2ex6-STAT6ex17. In addition, our meta-analysis revealed that the major fusion variant in meningeal SFT/HPC was NAB2ex6-STAT6ex16/17 (29/54, 54%), which was also common in soft tissue and intraperitoneum/retroperitoneum but rare in thoracic SFT. Fusion variant significantly correlated with age and histologic diagnosis in meningeal SFT/HPC but not with prognosis. Our results represented that meningeal SFT and HPC were in a single biological spectrum with NAB2-STAT6 gene fusion as was nonmeningeal SFT and further confirmed the organ-specific tumorigenic process and morphologic differences on the basis of fusion variants in meningeal SFT/HPC.

BACKGROUND. The demonstration of the monoclonality of immunoglobulin heavy chain (IgH) gene rearrangement is an indispensable method for the diagnosis of B-cell lymphoma as well as histocytochemical analysis. For the detection of IgH gene rearrangement, the extraction of DNA from a homogenous cell population is necessary. Recently, the laser capture microdissection (LCM) technique was shown to isolate specific cells from histopathologic specimens for molecular analysis. However, to the authors' knowledge the applicability of LCM to cytologic specimens has not yet been well established. METHODS. Using LCM, a homogenous population of B-cell lymphoma cells as both histologic sections and cytologic specimens was captured, and genomic DNA was extracted from the captured cells. IgH gene rearrangement was analyzed by the polymerase chain reaction (PCR)-based single-strand conformational polymorphism (SSCP) method. RESULTS. Genomic DNAs were extracted successfully from ethanol-fixed cytologic specimens, but cells were not captured from air-dried specimens. Using PCR-SSCP analysis, the monoclonality of the IgH gene rearrangement was detected in five cases of tissue sections among nine analyzed cases of malignant lymphoma diagnosed immunohistochemically. However, analysis of the cytologic specimens with LCM demonstrated the monoclonality of the IgH gene rearrangement in seven cases of lymphoma. CONCLUSIONS. The results of the current study suggest that the novel application of LCM to cytologic specimens occasionally exhibits high sensitivity for the detection of IgH gene rearrangement monoclonality compared with the use of histologic sections.

Introduction: Autophagy has not been studied extensively in the human placenta. This study was performed to determine whether autophagy is increased in the placentas of women with hypertensive disorders in pregnancy compared to normotensive pregnancies. Methods: LC3-II and p62 protein expression were examined by quantitative Western blotting analysis in 40 placentas from women not experiencing labor pains. The 40 placentas were from 13, 8, and 19 women with preeclampsia, gestational hypertension, and normal pregnancy, respectively. Hypertensive disorders in pregnancy included preeclampsia and gestational hypertension. Results: LC3-II expression was significantly increased, while that of p62 was significantly reduced in 21 placentas of women with hypertensive disorders compared to those with normal blood pressure irrespective of the presence or absence of fetal growth restriction (FGR). LC3-II expression was also significantly increased in 13 placentas of women with preeclampsia irrespective of the presence or absence of FGR. Discussion: The results of this study suggested that autophagy is active in the placenta of hypertensive disorders even in the absence of FGR. (C) 2014 Elsevier Ltd. All rights reserved.

A 75-year-old woman was admitted to our hospital with rapidly deteriorating consciousness disturbance. She had a 7-year history of rheumatoid arthritis (RA), which had been treated with methotrexate (MTX) and prednisolone. Brain T2-weighted MRI showed diffuse high-intensity lesions in the cerebral subcortical and deep white matter, bilateral basal ganglia and thalamus. A cerebrospinal fluid examination revealed elevated protein levels and positive Epstein-Barr virus (EBV) DNA. Human immunodeficiency virus was negative. Brain biopsy showed perivascular lymphocytic infiltration in the parenchyma and meninx with EBV-encoded small RNA (EBER). Since this case did not fulfill the criteria for chronic active EBV infection (CAEBV), she was diagnosed with Epstein-Barr virus (EBV)-associated vasculitis of the central nervous system. High-dose methylprednisolone, acyclovir, ganciclovir and foscarnet were not effective. Although EBV is a causative agent of infectious mononucleosis (IM), lymphomas and nasopharyngeal carcinomas, vasculitic pathology of the central nervous system with EBV reactivation in the elderly is rare. Immunosuppressive drugs such as steroids and MTX are widely used to treat autoimmune disorders, but may exacerbate the reactivation of EBV. This is the first case of biopsy-proven EBV-positive/HIV-negative vasculitis during the treatment of RA with MTX and steroids. This case indicates that EBV-associated vasculitis needs to be considered as a differential diagnosis of CNS vasculitis.

Background Lymph node metastasis is a key event of colorectal cancer (CRC) progression. Mesothelin is expressed in various types of malignant tumor and associated with an unfavorable prognosis. The full-length mesothelin (Full-ERC) is cleaved by protease into membrane-bound C-ERC/mesothelin and N-ERC/mesothelin which is secreted into the blood. The aim of this study was to examine the biological role of mesothelin in CRC by clinicopathological analysis and in vitro lymphatic invasion assay. Methods Ninety-one cases of CRC specimens were immunohistochemically examined and the localization of mesothelin in luminal membrane and/or cytoplasm was also evaluated. Lymphatic invasion assay was also performed using the human CRC cell line, WiDr, which was transfected with Full-, N- and C-ERC/mesothelin expression plasmids (Full-WiDr, N-WiDr and C-WiDr). Results Immunohistochemically, "luminal membrane positive" of mesothelin was identified in 37.4 %, and correlated with lymphatic permeation and lymph node metastasis, but not with patients' prognosis. Interestingly, among the patients with lymph node metastasis (N = 38), "luminal membrane positive" of mesothelin significantly correlated with unfavorable patients' outcome. In addition, lymphatic invasion assay revealed that Full-WiDr and C-WiDr more significantly invaded human lymphatic endothelial cells than the Mock-WiDr (P < 0.01). Conclusion The luminal membrane expression of mesothelin was associated with unfavorable prognosis of CRC patients with lymph nodemetastasis. Moreover, this is the first report to prove the biological function of C-ERC/mesothelin associated with lymphatic invasion of cancer in vitro.

Evaluation of O-6-methylguanine-DNA methyltransferase (MGMT) expression is important for antiglioma therapy as many clinical trials have demonstrated that promoter hypermethylation and low level expression of MGMT are associated with an enhanced response to alkylating agents. However, here we report that the current strategies used to evaluate MGMT status in gliomas are unreliable. We observed discordance in the MGMT expression status when immunohistochemical evaluation and polymerase chain reaction-based methylation assessments were used: 73% of gliomas with methylated MGMT promoter had substantial numbers of MGMT-immunopositive tumor cells. Furthermore, when MGMT expression was tested in tumor homogenates using reverse transcription-polymerase chain reaction, 43% of tumors were found positive, in comparison to only 24%, when histologic samples were assayed immunohistochemically. To explain these inconsistencies we undertook a detailed immunohistochemical evaluation of tumor samples and found that some gliomas demonstrated remarkably high expression of MGMT in the entire tumor whereas others contained only a small immunopositive area. Additionally, we found that gliomas contained various types of non-neoplastic cells expressing MGMT, including lymphocytes, vascular endothelial cells, and macrophages/microglias, which contribute to overall MGMT expression detected in tumor homogenates, and thus result in overestimation of tumor NIGMT expression. Therefore, to correctly establish MGMT expression in the tumor, which could be informative of glioma sensitivity to alkylating agents, exclusion of non-neoplastic brain components from analysis is required.

Recent genetic analyses using next-generation sequencers have revealed numerous genetic alterations in various tumors including meningioma, which is the most common primary brain tumor. However, their use as routine laboratory examinations in clinical applications for tumor genotyping is not cost effective. To establish a clinical sequencing system for meningioma and investigate the clinical significance of genotype, we retrospectively performed targeted amplicon sequencing on 103 meningiomas and evaluated the association with clinicopathological features. We designed amplicon-sequencing panels targeting eight genes including NF2 (neurofibromin 2), TRAF7, KLF4, AKT1, and SMO. Libraries prepared with genomic DNA extracted from PAXgenefixed paraffin-embedded tissues of 103 meningioma specimens were sequenced using the Illumina MiSeq. NF2 loss in some cases was also confirmed by interphase-fluorescent in situ hybridization. We identified NF2 loss and/or at least one mutation in NF2, TRAF7, KLF4, AKT1, and SMO in 81 out of 103 cases (79%) by targeted amplicon sequencing. On the basis of genetic status, we categorized meningiomas into three genotype groups: NF2 type, TRAKLS type harboring mutation in TRAF7, AKT1, KLF4, and/or SMO, and 'not otherwise classified' type. Genotype significantly correlated with tumor volume, tumor location, and magnetic resonance imaging findings such as adjacent bone change and heterogeneous gadolinium enhancement, as well as histopathological subtypes. In addition, multivariate analysis revealed that genotype was independently associated with risk of recurrence. In conclusion, we established a rapid clinical sequencing system that enables final confirmation of meningioma genotype within 7 days turnaround time. Our method will bring multiple benefits to neuropathologists and neurosurgeons for accurate diagnosis and appropriate postoperative management.

Human synovial sarcoma has been shown to exclusively harbor the chromosomal translocation t(X;18) that produces the chimeric gene SYT-SSX. However, the role of SYT-SSX in cellular transformation remains unclear. In this study, we have established 3Y1 rat fibroblast cell lines that constitutively express SYT, SSX1, and SYT-SSX1 and found that SYT-SSX1 promoted growth rate in culture, anchorage-independent growth in soft agar, and tumor formation in nude mice. Deletion of the N-terminal 181 amino acids of SYT-SSX1 caused loss of its transforming activity. Furthermore, association of SYT-SSX1 with the chromatin remodeling factor hBRM/hSNF2 alpha, which regulates transcription, was demonstrated in both SYT-SSX1-expressing 3Y1 cells and in the human synovial sarcoma cell line HS-SY-II. The binding region between the two molecules was shown to reside within the N-terminal 181 amino acids stretch (aa 1-181) of SYT-SSX1 and 50 amino acids (aa 156-205) of hBRM/hSNF2 alpha and we found that the overexpression of this binding region of hBRM/hSNF2 alpha significantly suppressed the anchorage-independent growth of SYT-SSX1-expressing 3Y1 cells. To analyze the transcriptional regulation by SYT-SSX1, we established conditional expression system of SYT-SSX1 and examined the gene expression profiles. The down-regulation of potential tumor suppressor DCC was observed among 1,176 genes analyzed by microarray analysis, and semi-quantitative reverse transcription-PCR confirmed this finding. These data clearly demonstrate transforming activity of human oncogene SYT-SSX1 and also involvement of chromatin remodeling factor hBRM/hSNF2 alpha in human cancer.

Mesothelin, C-ERC/mesothelin is a 40-kDa cell surface glycoprotein that is normally present on normal mesothelial cells lining the pleura, peritoneum, and pericardium. Moreover, mesothelin has been shown to be overexpressed in several human cancers, including virtually all mesothelioma and pancreatic cancer, approximately 70% of ovarian cancer and extra bile duct cancer, and 50% of lung adenocarcinomas and gastric cancer. The full-length human mesothelin gene encodes the primary product, a 71-kDa precursor protein. The 71-kDa mesothelin precursor is cleaved into two products, 40-kDa C-terminal fragment that remains membrane-bound via glycosylphosphatidylinositol anchor, and a 31-kDa N-terminal fragment, megakaryocyte potentiating factor, which is secreted into the blood. The biological functions of mesothelin remain largely unknown. However, results of recent studies have suggested that the mesothelin may play a role of cell proliferation and migration. In pancreatic cancer, mesothelin expression was immunohistochemically observed in all cases, but absent in normal pancreas and in chronic pancreatitis. Furthermore, the expression of mesothelin was correlated with an poorer patient outcome in several human cancers. The limited mesothelin expression in normal tissues and high expression in many cancers makes it an attractive candidate for cancer therapy. The present review discusses the expression and function of mesothelin in cancer cells and the utility of mesothelin as a target of cancer therapy.

BACKGROUND: As liquid-based cytology (LBC) specimens harbor high-quality DNA, genomic analysis using LBC specimens is beneficial for integrative diagnosis. This study aimed to clarify the feasibility of LBC specimens for a bimodal application of DNA- and RNA-based next-generation sequencing (NGS) panels. METHODS: LBC specimens were prepared from cultured human cancer HEC59 cells using commercially available fixatives (Cellprep, CytoRich Red, and SurePath solutions), and were subjected to NGS for a feasibility study. Clinical LBC specimens of thyroid and salivary gland tumors were prepared using CytoRich Red solution. After DNA and RNA extraction, NGS analyses were performed in a single run using combined DNA- and RNA-based custom-made cancer panels for the detection of gene mutations and fusions. RESULTS: High-quality DNA and RNA were obtained, and the expected gene mutations and fusions were detected in HEC59 cells using all types of LBC fixatives. Most available clinical cases (18 out of 20) exhibited pathogenic gene mutations (15 cases) and fusion genes (3 cases) using the bimodal DNA- and RNA-based panels. Overall, 18 cases (90%) showed oncogenic mutations or fusion genes of diagnostic values. CONCLUSION: Simultaneous application of bimodal DNA- and RNA-based gene panels was useful in NGS analysis using residual LBC specimens for integrative diagnosis. Residual LBC specimens for genomic analysis, including fusion gene analysis, are particularly useful for obtaining genomic information before surgical resection.

Objective Cardiovascular disease is a leading cause of sudden unexpected death even in hospitalized patients. Infectious aortitis is a rare disease that has the potential to cause aortic tears and hemorrhage followed by sudden death. The aim of this study was to reveal the clinicopathological features of infectious aortitis that are related to sudden unexpected death. Methods We retrospectively reviewed 1,310 autopsy cases over 15 years and selected the cases involving patients who died suddenly due to aortic tears. We analyzed the clinical information and pathological findings. Results One hundred thirty-three of 1,310 cases (10.2%) were autopsied under the clinical diagnosis of unexpected sudden death. Aortic tears were identified in 33 cases (2.5%) and infectious aortitis was diagnosed in 6 (18.2%) of these cases. All cases involved male patients (middle-aged to elderly) with risk factors for atherosclerosis (i.e., hypertension). The laboratory data showed continuous leukocytosis and C-reactive protein elevation, even during the improvement phase, in patients with pre-existing infectious disease. The autopsy findings revealed three types of aortic tears (aneurysms, dissections and penetrating atherosclerotic ulcers with moderate to severe atherosclerosis), and the infiltration of numerous neutrophils at the site of rupture. Gram-positive bacteria were detected in four cases and Gram-negative bacteria were detected in two cases. Discussion We demonstrated that sudden unexpected death caused by infectious aortitis rarely occurred in hospitalized patients, even in the recovery phase of the preceding infectious disease. We therefore recommend that clinicians pay attention to infectious aortitis in patients with infectious disease, particularly elderly patients with atherosclerotic disease, even those who are in the improvement phase. Conclusion Unexpected sudden death by infectious aortitis in the recovery phase of antecedent infection.

Atypical teratoid/rhabdoid tumor (AT/RT) is a malignant tumor that mostly occurs in early childhood and has poor prognosis despite aggressive therapy. Adult cases are rare and, as far as we are aware, only 30 cases have been reported to date. Here we present the case of a 27-year-old female with left parietal AT/RT with the chief complaint of numbness of the right superior limb. First, the tumor was surgically removed and the diagnosis was grade II glioma. With additional radiotherapy, the clinical course after surgery was favorable. After 6 years, she had an operation for recurrence and the diagnosis was grade III glioma. Temozolomide was prescribed, and a disease-free period of 2 years followed. Surgery was performed for a third time for second recurrence with histology of diffuse growth of rhabdoid cells. Immunohistochemistry was partially positive for vimentin and epithelial membrane antigen. Ki-67 labeling index was extremely high and tumor cells showed no staining of INI1 suggestive of diagnosis of AT/RT. We re-evaluated past specimens and none had immunoreactivity of INI1. Ki-67 labeling index and O-6 methylguanine DNA methyltransferase (MGMT) staining were also re-examined and both increased gradually. She is still alive without recurrence for more than 1 year. As far as we are aware, this is the second longest survival of an adult with AT/RT.

Lymphomatoid granulomatosis (LYG) in the central nervous system (CNS) is an uncommon lymphoproliferative disorder with low grade malignant potential. Here we report a case of CNS-LYG, in particular, its characteristics of radioisotope imaging and pathological findings. A 65-year-old man complained of visual disturbance and homonymous hemianopsia was designated. CT and MRI revealed an edematous, enhanced irregular and nodular lesion in the right occipital and parietal lobes. Although 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) scan showed low uptake in the lesion, Methionine (MET)-PET scan indicated high uptake. Proton magnetic resonance spectroscopy ((1)H-MRS) at 3T revealed a decrease of the peak of the N-acetylaspartate (NAA), suggesting a possible neoplastic lesion. The patient was diagnosed with CNS-LYG based on the surgically removed material showing perivascular infiltration of CD3-positive small T-lymphocytes with granulomatous lesions. The post-operative steroid therapy was effective and the recurrence or exacerbation has not been observed by radiological imaging until now.

Astroblastoma is a rare neuroepithelial neoplasm of unknown origin, usually occurring in children and young adults. Here we report a case of astroblastoma with uncommon features in an 18-year-old female. The tumor was a well-circumscribed cystic and solid mass with marked gadolinium enhancement in the right frontal lobe. Cytological examination showed polarized monopolar cells with diminished cohesiveness. Tumor cells possessed eccentric round to oval nuclei with abundant eosinophilic cytoplasm, sometimes having cytoplasmic processes. Histopathologically, the tumor showed perivascular pseudorosettes with prominent vascular sclerosis. Foam cells were frequently infiltrated around blood vessels and among tumor cells. In some areas, a solid growth pattern of plump tumor cells with abundant inclusion-like eosinophilic cytoplasm showing rhabdoid appearance was observed. The immunohistochemical study revealed strong and diffuse positivity for vimentin and epithelial membrane antigen. Tumor cells were focally positive for glial fibrillary acidic protein and cytokeratin AE1/AE3. Nuclear immunoreactivity for INI1 protein was evident. The Ki-67 labeling index was 10.8 %. This tumor was finally diagnosed as low-grade astroblastoma and the patient had no evidence of recurrence without postoperative radiotherapy or chemotherapy during the last 6 months of follow-up. This report describes novel cytological, histopathological, and immunohistochemical features of the rare tumor.

Central nervous system (CNS) neuroblastoma/ganglioneuroblastoma is one of the embryonal tumors with neuronal differentiation found in young adults, but it is most common in children, especially in those below the age of 5 years, whereas extraventricular neurocytoma, a rare neuroepithelial tumor with neuronal differentiation, mostly affects young adults. Here we present a rare case of cerebral ganglioneuronal tumor that occurred in a 32-year-old woman. The patient suffered from tonic convulsion, and computed tomography demonstrated a well-demarcated, round tumor 3.3 cm in size with marked calcification in the right parietal lobe. Histological analysis revealed diffuse infiltration of small, round cells with scattered large ganglion-like cells. Immunohistochemically, the tumor cells did not react with any neuronal molecules, except for chromogranin A in ganglion-like large tumor cells, but electron microscopy demonstrated the presence of synapse-like nerve terminal structures without mature postsynaptic density, suggesting the presence of neoplastic tumor components with neuronal differentiation; thus, this tumor was diagnosed as CNS ganglioneuroblastoma with possible low-grade malignancy because the Mib-1 labeling index was less than 3%-4%. Here we discuss the histological entity of cerebral ganglioneuronal tumors, including extraventricular neurocytoma.

We present a rare case of giant cell-rich solitary fibrous tumor (SFT) arising at the left external auditory canal in a 31-year-old woman. The tumor was well-circumscribed and composed of spindle-shaped cells with abundant collagenous bands. Scattered multinucleate giant cells were observed, some of which lined pseudovascular spaces. Although a focal mild-hypercellular area was observed, mitoses were rare and necrosis was absent. Interstitial mast cells were scattered, especially in the hypercellular area. Immunohistochemically, CD34, vimentin, and Bcl-2 presented diffuse positivity. Moreover, both mononuclear spindle cells and multinucleate cells showed nuclear STAT6 positivity, while NAB2-STAT6 fusion gene could not be detected by reverse transcription polymerase chain reaction using formalin-fixed specimen. These findings suggest the pathological diagnosis of giant cell-rich SFT, previously known as giant cell angiofibroma, which is a rare variant of SFT with multinucleate giant cells and occurs predominantly in orbital region. Although giant cell-rich SFTs of extra-orbital sites have been reported, to our knowledge, this is the first case arising in the external auditory canal. Giant cell-rich SFT should be considered as a differential diagnosis of spindle cell lesion with multinucleate giant cells, and STAT6 immunohistochemistry should be performed to distinguish this rare tumor from other mesenchymal neoplasms.

PURPOSE: A high proportion of patients with wild-type EGFR non-small cell lung cancer (NSCLC) receive third-line therapy and beyond, with no prospective randomized trials addressing the issue. This study aimed to select the most suitable regimen as a third- or fourth-line therapy for wild-type EGFR NSCLC. METHODS: This multicenter, randomized phase II study in Japan included patients with recurrent or advanced NSCLC with wild-type or unknown EGFR, who progressed after two or three previous chemotherapies. The patients were randomly assigned to erlotinib (150 mg/day, days 1-21) or S-1 (80-120 mg/day, days 1-14) every 3 weeks until disease progression or unacceptable toxicity. The primary endpoint was disease control rate (DCR). The secondary endpoints included overall survival (OS), progression-free survival (PFS), objective response rate (ORR), toxicity, and quality of life (QOL). RESULTS: From 2011 to 2016, 37 patients were randomly assigned to receive erlotinib (E arm, n = 19) and S-1 (S arm, n = 18). This study was terminated prematurely because of poor patient accrual. DCR/ORR were 42.1%/15.8% in the E arm and 66.7%/16.7% in the S arm. Median PFS/OS were 1.6 months/8.0 months in the E arm and 3.3 months/12.2 months in the S arm. In both groups, the most commonly reported grade 3-4 toxicities were fatigue, anorexia, and nausea. One grade 5 pneumonitis occurred in the S arm. No significant difference was seen in QOL. CONCLUSIONS: S-1 as a third- or fourth-line therapy for wild-type EGFR NSCLC showed numerically better clinical outcomes than erlotinib. CLINICAL TRIAL REGISTRATION NO: UMIN000005308.