Kohei Otsubo

Kohei Otsubo

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Research Focus & Metrics

Academic Career Length

20Years (2007-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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31 March 2022 in European Respiratory Journal
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Journal Article
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KOKohei Otsubo
Kohei Otsubo
JKJunji Kishimoto
Junji Kishimoto
MAMasahiko Ando
Masahiko Ando
HKHirotsugu Kenmotsu
Hirotsugu Kenmotsu
YMYuji Minegishi
Yuji Minegishi
IOIsamu Okamoto
Isamu Okamoto
Background: Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease implicated as an independent risk factor for lung cancer. However, optimal treatment for advanced lung cancer with IPF remains to be established. We performed a randomised phase 3 trial (J-SONIC) to assess the efficacy and safety of nintedanib plus chemotherapy (experimental arm) compared with chemotherapy alone (standard-of-care arm) for advanced nonsmall cell lung cancer (NSCLC) with IPF.Methods: Chemotherapy-naïve advanced NSCLC patients with IPF were allocated to receive carboplatin (area under the curve of 6 on day 1) plus nanoparticle albumin-bound paclitaxel (nab-paclitaxel) (100 mg·m−2on days 1, 8 and 15) every 3 weeks with or without nintedanib (150 mg twice daily, daily). The primary end-point was exacerbation-free survival (EFS).Results: Between May 2017 and February 2020, 243 patients were enrolled. Median EFS was 14.6 months in the nintedanib plus chemotherapy group and 11.8 months in the chemotherapy group (hazard ratio (HR) 0.89, 90% CI 0.67–1.17; p=0.24), whereas median progression-free survival was 6.2 and 5.5 months, respectively (HR 0.68, 95% CI 0.50–0.92). Overall survival was improved by nintedanib in patients with nonsquamous histology (HR 0.61, 95% CI 0.40–0.93) and in those at GAP (gender–age–physiology) stage I (HR 0.61, 95% CI 0.38–0.98). Seven (2.9%) out of 240 patients experienced acute exacerbation during study treatment.Conclusions: The primary end-point of the study was not met. However, carboplatin plus nab-paclitaxel was found to be effective and tolerable in advanced NSCLC patients with IPF. Moreover, nintedanib in combination with such chemotherapy improved overall survival in patients with nonsquamous histology.

26 October 2021 in Cancer Science
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Journal Article
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SSShinya Sakata
Shinya Sakata
KOKohei Otsubo
Kohei Otsubo
HYHisako Yoshida
Hisako Yoshida
KIKentaro Ito
Kentaro Ito
ANAtsushi Nakamura
Atsushi Nakamura
KNKazuhiko Nakagawa
Kazuhiko Nakagawa
Considering the increasing number of identified driver oncogene alterations, additional genetic tests are required to determine the treatment for advanced non‐small‐cell lung cancer (NSCLC). Next‐generation sequencing can detect multiple driver oncogenes simultaneously, enabling the analysis of limited amounts of biopsied tissue samples. In this retrospective, multicenter study (UMIN ID000039523), we evaluated real‐world clinical data using the Oncomine Dx Target Test Multi‐CDx System (Oncomine DxTT) as a companion diagnostic system. Patients with NSCLC who were tested for a panel of 46 genes using the Oncomine DxTT between June 2019 and January 2020 were eligible for enrollment. Patients from 19 institutions affiliated to the West Japan Oncology Group were recruited. The primary endpoint of the study was the success rate of genetic alteration testing in four driver genes (EGFR, ALK, ROS1, and BRAF) using the Oncomine DxTT. In total, 533 patients were enrolled in the study. The success rate of genetic alteration testing for all four genes was 80.1% (95% CI 76.5%‐83.4%). Surgical resection was associated with the highest success rate (88.0%), which was significantly higher than that for bronchoscopic biopsy (76.8%, P = .005). Multivariate analysis revealed a significant difference for surgical resection alone (P = .006, 95% CI 1.36‐6.18, odds ratio 2.90). Although the success rate of genetic alteration testing immediately after Oncomine DxTT induction was not sufficient in this study, optimizing specimen quantity and quality may improve the use of driver gene testing in clinical settings.

26 July 2017 in Cancer Science
Verified
Journal Article
Open access
KOKohei Otsubo
Kohei Otsubo
KNKaname Nosaki
Kaname Nosaki
CIChiyo K. Imamura
Chiyo K. Imamura
HOHiroaki Ogata
Hiroaki Ogata
AFAkitaka Fujita
Akitaka Fujita
IOIsamu Okamoto
Isamu Okamoto
Spliced variant isoforms of CD44 (CD44v) are a marker of cancer stem cells in solid tumors. They stabilize the xCT subunit of the transporter system xc(–) and thereby promote synthesis of the antioxidant glutathione. Salazosulfapyridine (SASP) is an inhibitor of xCT and suppresses the proliferation of CD44v‐positive cancer cells. Chemotherapy‐naïve patients with advanced non‐squamous non‐small‐cell lung cancer were enrolled in a dose‐escalation study (standard 3 + 3 design) of SASP in combination with cisplatin and pemetrexed. The primary end‐point was the percentage of patients who experience dose‐limiting toxicity. Fifteen patients were enrolled in the study. Dose‐limiting toxicity was observed in one of six patients at a SASP dose of 1.5 g/day (elevation of aspartate and alanine aminotransferase levels, each of grade 3), two of five patients at 3 g/day (hypotension or pneumonitis, each of grade 3), and two of three patients at 4.5 g/day (anorexia of grade 3). The maximum tolerated dose was thus 3 g/day, and the recommended dose was 1.5 g/day. The overall response rate was 26.7% and median progression‐free survival was 11.7 months, much longer than that for cisplatin–pemetrexed alone in previous studies. Exposure to SASP varied markedly among individuals according to ABCG2 and NAT2 genotypes. The serum concentration of free CD44v protein was increased after the first cycle of treatment, possibly reflecting death of cancer stem cells. Salazosulfapyridine was thus given safely in combination with cisplatin–pemetrexed, with the addition of SASP tending to prolong progression‐free survival. This trial is registered in the UMIN Clinical Trials Registry as UMIN000017854.

30 June 2022 in European Journal of Cancer
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Journal Article
Closed access
KTKazuki Takada
Kazuki Takada
SBSebastiano Buti
Sebastiano Buti
MBMelissa Bersanelli
Melissa Bersanelli
MSMototsugu Shimokawa
Mototsugu Shimokawa
STShinkichi Takamori
Shinkichi Takamori
Tomoharu YoshizumiTomoharu Yoshizumi
Tomoharu Yoshizumi

25 April 2019 in The Oncologist
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Journal Article
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KOKohei Otsubo
Kohei Otsubo
KSKazuko Sakai
Kazuko Sakai
MTMasafumi Takeshita
Masafumi Takeshita
DHDaijiro Harada
Daijiro Harada
KAKoichi Azuma
Koichi Azuma
IOIsamu Okamoto
Isamu Okamoto
Patients with non-small cell lung cancer (NSCLC) treated with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) eventually acquire resistance to these drugs. The identification of various resistance mechanisms for determination of subsequent treatment for these patients will require a method for simultaneous detection of multiple genetic alterations with high sensitivity. We performed cancer personalized profiling by deep sequencing (CAPP-Seq) with circulating tumor DNA obtained from patients with NSCLC who acquired resistance to first- or second-generation EGFR-TKIs. Plasma samples from 27 patients were analyzed, and 24 samples underwent CAPP-Seq successfully. Original activating EGFR mutations were detected in 23 patients, with the remaining patient showing MET amplification. With regard to known mechanisms of EGFR-TKI resistance, the T790M mutation of EGFR was detected in 17 of the 24 patients, MET amplification in 9 patients (6 of whom also harbored T790M), ERBB2 amplification in 2 patients (1 of whom also harbored T790M), and EGFR amplification in 4 patients (all of whom harbored T790M). Our results thus show that CAPP-Seq is applicable to clinical samples for the identification of multiple somatic mutations in circulating tumor DNA obtained from patients with NSCLC at the time of disease progression during treatment with first- or second-generation EGFR-TKIs. Patients positive for the T790M mutation of EGFR were also found to constitute a molecularly heterogeneous population. Key Points: CAPP-Seq is applicable to clinical samples for the identification of multiple somatic mutations. The T790M mutation of EGFR is associated with amplification of MET, ERBB2, or EGFR in NSCLC patients resistant to EGFR-TKIs. T790M-positive patients are molecularly heterogeneous, and genetic alterations coexisting with T790M may differ between patients treated with first-generation or second-generation EGFR-TKIs.

1 July 2018 in Respiratory Investigation
Verified
Journal Article
Closed access
KOKohei Otsubo
Kohei Otsubo
IOIsamu Okamoto
Isamu Okamoto
NHNaoki Hamada
Naoki Hamada
YNYoichi Nakanishi
Yoichi Nakanishi