Investigator

Yusuke Kobayashi

Professor · University of Tsukuba, Faculty of Medicine

Research Interests

YKYusuke Kobayashi
Papers(12)
A randomized phase II…Current treatment str…Retrospective evaluat…Management of ovarian…Current status and fu…Current status of her…Efficacy and safety o…Primary malignant mel…Time for enhancing go…Significance of PD-L1…Development of a prog…Clinical availability…
Collaborators(10)
Daisuke AokiKouji BannoJae-Weon KimTomoko YoshihamaKensuke SakaiWataru YamagamiHiroaki KajiyamaTakashi IwataTakayuki EnomotoSatoru Nagase
Institutions(7)
University Of TsukubaKeio UniversityKeio UniversitySeoul National Univer…Nagoya UniversityNiigata University Gr…Yamagata University F…

Papers

A randomized phase II study of secondary cytoreductive surgery in patients with relapsed ovarian cancer who have progressed on a PARP inhibitor as first-line maintenance therapy: the SOCCER-P study (KGOG 3067/JGOG 3036/APGOT-OV11)

Although two recent phase III randomized controlled trials showed survival benefits of undergoing secondary cytoreductive surgery for an initial relapse of ovarian cancer, patients who received a poly-ADP ribose polymerase inhibitor (PARPi) as the first-line maintenance treatment, which is currently the standard treatment for advanced ovarian cancer, were not included in those trials. Therefore, determining an optimal treatment strategy, including secondary cytoreductive surgery, in patients whose cancer progresses even with PARPi treatment, is needed. To determine whether secondary cytoreductive surgery is beneficial in patients who have progressed on PARPi maintenance treatment. Secondary cytoreductive surgery followed by chemotherapy is superior to chemotherapy alone for patients who have progressed on PARPi maintenance treatment. The SOCCER-P study is a multicenter randomized phase II clinical trial. Patients who meet the eligibility criteria will be randomized to either undergo secondary cytoreductive surgery and subsequent platinum-based chemotherapy plus or minus bevacizumab, or to receive platinum-based chemotherapy plus or minus bevacizumab alone. Patients randomly allocated to the surgery group will undergo secondary cytoreductive surgery followed by six cycles of a physician's choice of platinum-based chemotherapy once they have recovered from surgery. The major inclusion criteria are as follows: first recurrence of disease with treatment-free interval from last platinum dose (TFIp) ≥6 months and progression during PARPi maintenance or treatment-free interval from last PARPi therapy (TFI Progression-free survival. 124 patients. Accrual completion approximately the end of 2026 and the results are expected after 2 years of follow-up in 2029. NCT05704621.

Current treatment strategies for ovarian cancer in the East Asian Gynecologic Oncology Trial Group (EAGOT)

Ovarian cancer, notable for its severe prognosis among gynecologic cancers, has seen substantial progress in treatment approaches recently. Enhanced protocols in chemotherapy and the introduction of poly (ADP-ribose) polymerase (PARP) inhibitors for maintenance therapy have markedly improved outcomes for patients with specific genetic profiles, such as those positive for BRCA mutations or exhibiting homologous recombination deficiency (HRD). Additionally, the method of intraperitoneal chemotherapy administration has emerged as a valuable alternative to traditional transvenous routes, showing promise for wider clinical adoption. The field of surgery has also evolved, with increasing exploration into the benefits and feasibility of laparoscopic methods over more invasive traditional surgeries, aiming for complete tumor removal but with reduced patient impact. The hereditary nature of ovarian cancer underscores the importance of genetic testing, which has become integral in tailoring treatment strategies, particularly in determining suitability for PARP inhibitors. The formation of the East Asian Gynecologic Oncology Trial Group (EAGOT) aims to optimize treatment across Japan, Korea, China, and Taiwan. The ovarian cancer committee of EAGOT shared the current policies, focusing on 5 topics: 1) strategies for maintenance therapy after initial surgery and chemotherapy, 2) drug regimens for platinum-sensitive and platinum-resistant recurrence, 3) intraperitoneal chemotherapy, 4) laparoscopic surgery as an alternative to laparotomy, and 5) current status of genetic testing (BRCA, HRD, and panel tests) for ovarian cancer and its prospects. EAGOT's multi-national trials aim to harmonize these evolving treatment strategies, ensuring that the latest and most effective protocols are accessible across the region, thereby significantly impacting patient outcomes in East Asia.

Retrospective evaluation of risk-reducing salpingo-oophorectomy for BRCA1/2 pathogenic variant carriers among a cohort study in a single institution

Abstract Background Risk-reducing salpingo-oophorectomy is performed for the primary prevention of ovarian cancer in patients with hereditary breast–ovarian cancer syndrome. We performed risk-reducing salpingo-oophorectomy for the first time in Japan in 2008, and we experienced 20 cases of risk-reducing salpingo-oophorectomy through 2019. In the past, the use of risk-reducing salpingo-oophorectomy in Japan was restricted because it was not covered by a Japanese National Health Insurance. Since April 2020, risk-reducing salpingo-oophorectomy has been covered by insurance for patients with breast–ovarian cancer syndrome and pre-existing breast cancer, and this surgery is expected to become more widely implemented in Japan. Methods To contribute to the widespread use of risk-reducing salpingo-oophorectomy in the future, we retrospectively reviewed 20 cases of risk-reducing salpingo-oophorectomy at our hospital cohort study to clarify the issues in its implementation. Results The variant genes for which risk-reducing salpingo-oophorectomy was indicated were BRCA1 and BRCA2 in 13 (65%) and 7 patients (35%), respectively. The median age at which risk-reducing salpingo-oophorectomy was performed was 49 years (range, 38–58), 13 patients (65%) had gone through menopause, and 16 patients (80%) had a history of breast cancer. Of the five patients (25%) with vasomotor symptoms, four received Chinese medicine, and only one received hormone replacement therapy. Occult cancer was detected in the removed ovaries in two patients (10%), although no postoperative peritoneal carcinogenesis has been observed to date. Conclusions Women who paid for risk-reducing salpingo-oophorectomy out of pocket were older than the recommended age at which the procedure should be performed, and this may explain the higher rate of occult cancers than previously reported. We need to perform risk-reducing salpingo-oophorectomy at the recommended age to ensure that the procedure is effective for primary prevention.

Current status of hereditary breast and ovarian cancer practice among gynecologic oncologists in Japan: a nationwide survey by the Japan Society of Gynecologic Oncology (JSGO)

The practices pertaining to hereditary breast and ovarian cancer (HBOC) in Japan have been rapidly changing owing to the clinical development of poly(ADP-ribose) polymerase inhibitors, the increasing availability of companion diagnostics, and the broadened insurance coverage of HBOC management from April 2020. A questionnaire of gynecologic oncologists was conducted to understand the current status and to promote the widespread standardization of future HBOC management. A Google Form questionnaire was administered to the members of the Japan Society of Gynecologic Oncology. The survey consisted of 25 questions in 4 categories: respondent demographics, HBOC management experience, insurance coverage of HBOC management, and educational opportunities related to HBOC. A total of 666 valid responses were received. Regarding the prevalence of HBOC practice, the majority of physicians responded in the negative and required human resources, information sharing and educational opportunities, and expanded insurance coverage to adopt and improve HBOC practice. Most physicians were not satisfied with the educational opportunities provided so far, and further expansion was desired. They remarked on the psychological burdens of many HBOC managements. Physicians reported these burdens could be alleviated by securing sufficient time to engage in HBOC management, creating easy-to-understand explanatory material for patients, collaboration with specialists in genetic medicine, and educational opportunities. Gynecologic oncologists in Japan are struggling to deal with psychological burdens in HBOC practice. To promote the clinical practice of HBOC management, there is an urgent need to strengthen human resources and improve educational opportunities, and expand insurance coverage for HBOC management.

Efficacy and safety of olaparib maintenance monotherapy for Japanese patients with platinum-sensitive relapsed ovarian, fallopian tube, and primary peritoneal cancer

Olaparib maintenance therapy for platinum-sensitive relapsed ovarian cancer has been approved in Japan since April 2018. Here, we report the experience administering this therapy in our hospital, with the aim of evaluating efficacy and safety in the Japanese population. The study included 52 patients with platinum-sensitive relapsed ovarian, fallopian tube, and primary peritoneal cancer. All patients started olaparib at a dose of 300 mg twice daily. Information about treatment efficacy and adverse effects was collected retrospectively from medical records. Median age was 58 years old (range: 33-80), and 82.7% of the patients were diagnosed with high-grade serous carcinoma. Sixteen patients (30.8%) possessed the BRCA1/2 pathogenic variant (15 germline and 1 tissue), 3 (5.8%) possessed variants of unknown significance (2 germline and 1 tissue), 16 (30.8%) possessed wild type, and 17 (32.7%) were not analyzed. Median progression-free survival was 15.3 months (95% CI 9.0-21.6). Patients with BRCA1/2 pathogenic variants showed significantly longer PFS than patients with wild-type BRCA1/2 (p = 0.007). Disease progression caused 34 cases to discontinue olaparib. Eighteen (34.6%) individuals exhibited ≥ grade 3 anemia, although they recovered in response to appropriate management. One patient discontinued olaparib because of prolonged renal dysfunction. Another patient presented with grade 3 fatigue, but recovered after 2 weeks of interruption and continued olaparib treatment. Olaparib maintenance therapy for platinum-sensitive recurrent ovarian cancer in the Japanese population is sufficiently safe and no less effective than reports from previous studies.

Significance of PD-L1 expression in carbon-ion radiotherapy for uterine cervical adeno/adenosquamous carcinoma

Programmed cell death-ligand 1 (PD-L1) is expressed in tumor cells and has been shown to predict clinical outcomes of several types of malignancies. The aim of this study was to investigate the effects of carbon-ion (C-ion) beam irradiation on PD-L1 expression in human uterine cervical adeno/adenosquamous carcinoma (UCAA) cells and clinical samples and to identify the prognostic factors for outcomes after C-ion radiotherapy (CIRT). The effects of C-ion irradiation on PD-L1 expression in human UCAA and cervical squamous cell carcinoma cells were examined by flow cytometry. We examined PD-L1 expression in UCAA biopsy specimens from 33 patients before CIRT started (pre-CIRT) and after 12 Gy (relative biological effectiveness [RBE]) irradiation (post-12Gy-C) in 4 fractions of CIRT to investigate the correlation between PD-L1 status and clinical outcomes. The PD-L1 expression was upregulated by C-ion beam in a dose-dependent manner in HeLa and SiHa cells through phosphorylated Chk1. The overall frequencies of pre-CIRT and post-12Gy-C PD-L1 positivity were 45% (15/33) and 67% (22/33), respectively. The post-12Gy-C PD-L1 expression was significantly elevated compared to the pre-CIRT PD-L1 expression. There was no significant relationship between the pre-CIRT PD-L1 status and clinical outcomes, such as local control (LC), progression-free survival (PFS), and overall survival (OS). However, the post-12Gy-C PD-L1 expression had better correlation with PFS, but not with LC and OS. CIRT can induce PD-L1 expression in UCAA and we propose that PD-L1 expression after starting CIRT may become as a predictive prognostic marker in CIRT for UCAA.

Development of a prognostic prediction support system for cervical intraepithelial neoplasia using artificial intelligence-based diagnosis

Human papillomavirus subtypes are predictive indicators of cervical intraepithelial neoplasia (CIN) progression. While colposcopy is also an essential part of cervical cancer prevention, its accuracy and reproducibility are limited because of subjective evaluation. This study aimed to develop an artificial intelligence (AI) algorithm that can accurately detect the optimal lesion associated with prognosis using colposcopic images of CIN2 patients by utilizing objective AI diagnosis. We identified colposcopic findings associated with the prognosis of patients with CIN2. We developed a convolutional neural network that can automatically detect the rate of high-grade lesions in the uterovaginal area in 12 segments. We finally evaluated the detection accuracy of our AI algorithm compared with the scores by multiple gynecologic oncologists. High-grade lesion occupancy in the uterovaginal area detected by senior colposcopists was significantly correlated with the prognosis of patients with CIN2. The detection rate for high-grade lesions in 12 segments of the uterovaginal area by the AI system was 62.1% for recall, and the overall correct response rate was 89.7%. Moreover, the percentage of high-grade lesions detected by the AI system was significantly correlated with the rate detected by multiple gynecologic senior oncologists (r=0.61). Our novel AI algorithm can accurately determine high-grade lesions associated with prognosis on colposcopic images, and these results provide an insight into the additional utility of colposcopy for the management of patients with CIN2.

Clinical availability and characteristics of multigene panel testing for recurrent/advanced gynecologic cancer

Japan's health insurance covers multigene panel testing. This study aimed to determine the potential availability and utility of gene panel testing clinically in gynecologic oncology. We analyzed the characteristics of patients with gynecologic cancer who underwent gene panel testing using FoundationOne Out of 102 patients analyzed, 32, 18, 43, 8, and 1 had cervical, endometrial, ovarian cancers, sarcoma, and vaginal cancer, respectively. Druggable gene alteration was found in 70 patients (68.6%; 21 with cervical cancer, 15 with endometrial cancer, 28 with ovarian cancer, 5 with sarcoma, and 1 with other). The most common druggable gene alteration was PIK3CA mutation (n = 21), followed by PTEN mutation (n = 12) and high tumor mutation burden (TMB-H) (n = 11). TMB-H was detected in 5 patients with cervical cancer, 5 with endometrial cancer, and 1 with endometrial stromal sarcoma. Eleven patients (10.8%) received molecularly targeted therapy according to their gene aberrations. Gene panel testing was mostly performed when the second-line treatment was ineffective. Of all 102 patients, 60 did not have recommended treatment, and 15 died or had worsened conditions before obtaining the test results. Through multigene panel testing, although many patients had druggable gene alterations, 10.8% of them received the recommended treatment. TMB-H was mainly observed in cervical/endometrial cancer, suggesting its potential as a therapeutic biomarker of immune checkpoint inhibitors. Furthermore, patients' prognosis and performance status should be considered before performing the test.

Clinical-grade autonomous cytopathology through whole-slide edge tomography

Abstract Cytopathology, often abbreviated as cytology, has a central role in the early detection of cancer, such as cervical, lung and bladder cancers, owing to its speed, simplicity and minimally invasive nature 1–9 . However, its effectiveness is limited by variability in diagnostic accuracy stemming from subjective visual interpretation 10–21 . Although many artificial intelligence (AI)-powered systems have been proposed to improve consistency 22–26 , none have achieved fully autonomous, clinical-grade performance. Existing approaches serve as assistive tools and still rely on human oversight for interpretation and decision-making 22–26 . Here we present a clinical-grade autonomous cytopathology pipeline that combines high-resolution, real-time optical whole-slide tomography with edge computing to deliver end-to-end automation. The system achieves practical performance in imaging speed, quality and data volume, with localized data compression enabling streamlined storage and accelerated AI-driven analysis. In addition to supporting cell-level classification, the platform enables flow cytometry-like, population-wide morphological profiling for comprehensive interpretation of cellular distributions and patterns. A vision transformer achieved area under the receiver operating characteristic (ROC) curve (AUC) values exceeding 0.99 at the single-cell level for detecting low-grade squamous intraepithelial lesions (LSILs), high-grade squamous intraepithelial lesions (HSILs) and adenocarcinoma. In a multicentre evaluation of 1,124 cervical liquid-based cytology samples across four centres, the AI model achieved slide-level AUC values of 0.86–0.91 for LSIL + and 0.89–0.97 for HSIL + , with LSIL counts correlating strongly with human papillomavirus positivity and HSIL counts scaling with diagnostic severity. The system enables autonomous triage cytology, offering a foundation for routine, scalable and objective diagnostics.

127Works
13Papers
89Collaborators
1Trials
Ovarian NeoplasmsCarcinoma, Ovarian EpithelialNeoplasm Recurrence, LocalEndometrial NeoplasmsPrognosisPapillomavirus Infections

Positions

2023–

Professor

University of Tsukuba · Faculty of Medicine

2003–

Researcher

Keio University School of Medicine · Obstetrics and Gynecology

Links & IDs
0000-0002-4503-2845

Scopus: 36079665900