Masashi Wakabayashi

Dr. Masashi Wakabayashi


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

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

Representative Publications

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24 July 2019 in Journal for ImmunoTherapy of Cancer
Verified
Journal Article
Open access
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KSKohei Shitara
Kohei Shitara
SUSatoshi Ueha
Satoshi Ueha
SSShigeyuki Shichino
Shigeyuki Shichino
HAHiroyasu Aoki
Hiroyasu Aoki
HOHaru Ogiwara
Haru Ogiwara
TDToshihiko Doi
Toshihiko Doi
Background Transient CD4+ T cell depletion led to the proliferation of tumor-specific CD8+ T cells in the draining lymph node and increased infiltration of PD-1+CD8+ T cells into the tumor, which resulted in strong anti-tumor effects in tumor-bearing mice. This is a first-in-human study of IT1208, a defucosylated humanized anti-CD4 monoclonal antibody, engineered to exert potent antibody-dependent cellular cytotoxicity. Methods Patients with advanced solid tumors were treated with intravenous IT1208 at doses of 0.1 or 1.0 mg/kg. The first patient in each cohort received a single administration, and the other patients received two administrations of IT1208 on days 1 and 8. Results Eleven patients were enrolled in the 0.1 mg/kg (n = 4) and 1.0 mg/kg cohorts (n = 7). Grade 1 or 2 infusion-related reactions was observed in all patients. Decreased CD4+ T cells in peripheral blood due to IT1208 were observed in all patients and especially in those receiving two administrations of 1.0 mg/kg. CD8+ T cells increased on day 29 compared with baseline in most patients, resulting in remarkably decreased CD4/8 ratios. One microsatellite-stable colon cancer patient achieved durable partial response showing increased infiltration of both CD4+ and CD8+ T cells into tumors after IT1208 administration. Moreover, transcriptomic profiling of the liver metastasis of the patient revealed upregulation of the expression of interferon-stimulated genes, T cell activation-related genes, and antigen presentation-related genes after IT1208 administration. Two additional patients with gastric or esophageal cancer achieved stable disease lasting at least 3 months. Conclusions IT1208 monotherapy successfully depleted CD4+ T cells with a manageable safety profile and encouraging preliminary efficacy signals, which warrants further investigations, especially in combination with immune checkpoint inhibitors.

16 May 2024 in American Journal of Gastroenterology
Verified
Journal Article
Open access
TKTomohiro Kadota
Tomohiro Kadota
SASeiirhicro Abe
Seiirhicro Abe
NUNoriya Uedo
Noriya Uedo
HDHisashi Doyama
Hisashi Doyama
YFYasuaki Furue
Yasuaki Furue
Tomonori YanoTomonori Yano
Tomonori Yano
INTRODUCTION: The early detection of gastric neoplasms (GNs) leads to favorable treatment outcomes. The latest endoscopic system, EVIS X1, includes third-generation narrow-band imaging (3G-NBI), texture and color enhancement imaging (TXI), and high-definition white-light imaging (WLI). Therefore, this randomized phase II trial aimed to identify the most promising imaging modality for GN detection using 3G-NBI and TXI. METHODS: Patients with scheduled surveillance endoscopy after a history of esophageal cancer or GN or preoperative endoscopy for known esophageal cancer or GN were randomly assigned to the 3G-NBI, TXI, or WLI groups. Endoscopic observations were performed to detect new GN lesions, and all suspected lesions were biopsied. The primary endpoint was the GN detection rate during primary observation. Secondary endpoints were the rate of missed GNs, early gastric cancer detection rate, and positive predictive value for a GN diagnosis. The decision rule had a higher GN detection rate between 3G-NBI and TXI, outperforming WLI by >1.0%. RESULTS: Finally, 901 patients were enrolled and assigned to the 3G-NBI, TXI, and WLI groups (300, 300, and 301 patients, respectively). GN detection rates in the 3G-NBI, TXI, and WLI groups were 7.3, 5.0, and 5.6%, respectively. The rates of missed GNs were 1.0, 0.7, and 1.0%, the detection rates of early gastric cancer were 5.7, 4.0, and 5.6%, and the positive predictive values for the diagnosis of GN were 36.5, 21.3, and 36.8% in the 3G-NBI, TXI, and WLI groups, respectively. DISCUSSION: Compared with TXI and WLI, 3G-NBI is a more promising modality for GN detection.

11 June 2025 in Cancers
Verified
Journal Article
Open access
PDF file
KHKouta Hirotaki
Kouta Hirotaki
KMKenji Makita
Kenji Makita
MNMasaki Nakamura
Masaki Nakamura
MWMasashi Wakabayashi
Masashi Wakabayashi
SKSatoe Kitou
Satoe Kitou
MIMasashi Ito
Masashi Ito
Objectives: Although hippocampal-sparing whole-brain irradiation (HS-WBI) offers potential neurocognitive benefits, it poses challenges in treatment planning. This study aimed to compare the dose distributions of biaxially rotational dynamic radiation therapy (BROAD-RT) with a novel O-ring-type linear accelerator (OXRAY) and conventional non-coplanar volumetric modulated arc therapy (VMAT) planning (Conv-VMAT) in HS-WBI treatment plans. Methods: This study included 10 patients with brain metastases from lung cancer at our institution. The hippocampus was contoured using gadolinium-based contrast-enhanced magnetic resonance imaging, and hippocampal-sparing regions were created using a 5 mm margin around the hippocampus. Two virtual plans (BROAD-RT and Conv-VMAT) with 30 Gy in 10 fractions were created to compare the dose distributions in the planning target volume (PTV), hippocampus, eyes, and lens. All plans were analyzed using a paired t-test. Results: The mean (standard deviation [SD]) hippocampus-Dmax, -Dmean, -D100%, and -V10 were 11.10 (0.61), 7.95 (0.20), 7.01 (0.19), and 0.42 (0.34) for BROAD-RT and 16.10 (0.57), 9.89 (0.75), 8.24 (0.34), and 39.05 (25.89) for Conv-VMAT, respectively. All hippocampal parameters were significantly better with BROAD-RT than with Conv-VMAT (p < 0.01). The PTV-D98, -D50, -D2, -V35, and -homogeneity index did not exhibit significant differences between BROAD-RT and Conv-VMAT. Although lens-Dmax was significantly better in BROAD-RT than in Conv-VMAT (p < 0.01), no significant differences were observed in the eye-Dmax and chiasm-Dmax between BROAD-RT and Conv-VMAT. The mean (SD) BROAD-RT beam delivery time was 313.60 (34.91) s. Conclusions: BROAD-RT improved hippocampal sparing with acceptable PTV coverage and PTV homogeneity in HS-WBI planning. In addition, BROAD-RT has a clinically acceptable treatment duration.

1 June 2026 in Cancers
Verified
Journal Article
Open access
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HIHiroshi Imaoka
Hiroshi Imaoka
MIMasafumi Ikeda
Masafumi Ikeda
MWMasashi Wakabayashi
Masashi Wakabayashi
KUKumiko Umemoto
Kumiko Umemoto
TSTomoyuki Satake
Tomoyuki Satake
Junji FuruseJunji Furuse
Junji Furuse
Polyploid giant cancer cells (PGCCs) are characterized by abnormal enlargement and considerable polyploidy. Though the presence of giant cancer cells has been documented for decades, they remain not fully understood, especially in clinical practice, due to diagnostic challenges, and confusion regarding synonyms for PGCCs still exists. Thus, understanding PGCCs may be a key clue to overcoming them. This review offers a comprehensive overview of PGCCs, integrating insights from basic research and clinical studies to enhance understanding of their complex biology and clinical implications. In basic research, PGCCs are known to emerge under various stressors, including chemotherapy exposure, radiation, viral infection, and hypoxic environments. These cells play crucial roles in tumor progression through multiple mechanisms: enhancing genetic diversity, and facilitating metastatic spread via asymmetrical cell division and genomic instability. In clinical studies, PGCC-containing tumors have been shown to exhibit marked treatment resistance and are associated with a poor prognosis across multiple solid tumor types, including prostate, lung, and pancreatic cancers. Despite these therapeutic challenges, taxane-based chemotherapy has shown promising results in PGCC-containing tumors, such as pleomorphic carcinoma and undifferentiated carcinoma. Furthermore, emerging targeted therapies directed at specific pathways in PGCCs, particularly those involving TP53, represent potential strategies to improve clinical outcomes of patients with PGCC-containing tumors.

30 December 2024 in Supportive Care in Cancer
Verified
Journal Article
Closed access
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THTakuya Higashino
Takuya Higashino
MWMasashi Wakabayashi
Masashi Wakabayashi
SZSadamoto Zenda
Sadamoto Zenda
YYYoshichika Yasunaga
Yoshichika Yasunaga
JAJun Araki
Jun Araki
KYKotaro Yoshimura
Kotaro Yoshimura

10 February 2026 in Cancers
Verified
Journal Article
Open access
PDF file
EKEmi Kubo
Emi Kubo
ESEriko Satomi
Eriko Satomi
TMToru Mukohara
Toru Mukohara
NFNozomu Fuse
Nozomu Fuse
MWMasashi Wakabayashi
Masashi Wakabayashi
ASAkihiro Sato
Akihiro Sato
Background/Objectives: Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of taxanes and platinum-based agents, impairing quality of life. Duloxetine is the only drug with proven efficacy, but is often limited by tolerability. AT-04 is a portable alternating magnetic field device that activates descending pain modulatory systems and has shown safety in other pain settings. This investigator-initiated trial evaluated the efficacy and safety of AT-04 for persistent CIPN. Methods: We conducted a randomized, double-blind, sham-controlled, multicenter phase II study. Patients with CIPN lasting ≥12 weeks after chemotherapy and pain NRS ≥ 4 were enrolled. Participants used AT-04 or sham devices twice daily for 12 weeks. The primary endpoint was the change in pain NRS on day 85. Secondary endpoints included tingling NRS, numbness NRS, CIPN20 subscales, and safety. Results: Twenty-eight patients were randomized (14 per arm). No significant difference was observed in pain NRS on day 85 {AT-04: −1.74 ± 0.6 vs. sham device: −1.45 ± 0.6; one-sided p = 0.36, effect size (ES) = 0.48}. CIPN20 motor scores improved with AT-04 on days 29 (−9.82 ± 13.8 vs. 0.74 ± 8.7, respectively; p = 0.035, ES = 0.92) and 57 (−11.81 ± 10.6 vs. −0.54 ± 6.7, respectively; p < 0.01, ES = 1.26). Among patients whose last chemotherapy had ended >1 year earlier (n = 16), motor scores improved from days 29 (−12.43 ± 10.3 vs. 2.38 ± 8.9, respectively; p < 0.01, ES = 1.55) to 85 (−11.76 ± 10.1 vs. −0.07 ± 11.5, respectively; p = 0.049, ES = 1.08), while sensory/autonomic scales showed trends. No treatment-related adverse events occurred in the AT-04 group. Conclusions: AT-04 did not significantly reduce pain NRS but improved motor function in CIPN patients, especially in those >1 year after chemotherapy. AT-04 may be a promising non-pharmacological option; larger confirmatory trials are required.