Isaku Okamoto

Dr. Isaku Okamoto

Tokyo Medical University, Tokyo, Japan
orcid

Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

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

Representative Publications

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28 August 2019 in Acta Oto-Laryngologica
Verified
Journal Article
Closed access
IOIsaku Okamoto
Isaku Okamoto
HSHiroki Sato
Hiroki Sato
TKTakahito Kondo
Takahito Kondo
NKNobuyuki Koyama
Nobuyuki Koyama
CFChihiro Fushimi
Chihiro Fushimi
KTKiyoaki Tsukahara
Kiyoaki Tsukahara
Background: No large-scale retrospective studies have examined the efficacy and safety of nivolumab. Objective: This retrospective study aimed to investigate the efficacy and safety of nivolumab administered to patients in multiple facilities. Material and methods: The primary endpoint was overall response rate (ORR) and secondary endpoints were progression-free survival (PFS) and overall survival (OS). For safety, adverse event occurrence rates by grade, deaths and severe adverse events were investigated. OS and PFS were also examined according to whether immune-related adverse events (irAEs) appeared. Statistical analysis was conducted using log-rank testing, with values of p < .05 considered significant. Results: Nivolumab was administered to 100 patients with a history of receiving platinum-based drugs. ORR was 13.5% and disease control rate was 49.0%. Median PFS was 3.7 months. Median OS was 9.6 months. For all grades, irAEs occurred in 30 patients. The 1-year survival rate in the subgroup without irAEs was 34.0%, compared to 52.6% with irAEs (p = .041). Conclusions and significance: The 1-year survival rate was better in patients who developed irAEs. This is a new finding for head and neck cancer. Appearance of irAEs could also be used as an indicator of expected therapeutic effect in head and neck cancer.

11 September 2022 in Cancers
Verified
Journal Article
Open access
PDF file
IOIsaku Okamoto
Isaku Okamoto
TOTakuro Okada
Takuro Okada
KTKunihiko Tokashiki
Kunihiko Tokashiki
KTKiyoaki Tsukahara
Kiyoaki Tsukahara
Head and neck photoimmunotherapy (HN-PIT), a new treatment developed for local control of head and neck carcinoma, uses cetuximab sarotalocan sodium with a laser system to specifically destroy only tumor cells. No studies have examined the impact of HN-PIT on the quality of life (QOL) of patients with head and neck cancer. This study assessed the QOL of patients with unresectable locally advanced or locally recurrent head and neck carcinoma (LA/LR-HNC) treated with HN-PIT. Nine eligible patients with unresectable LA/LR-HNC who underwent HN-PIT at our institution between 20 January 2021 and 30 April 2022 were included in the study. They completed a QOL evaluation form. The primary endpoint was QOL assessment. The secondary endpoints were overall response rate, overall survival (OS), progression-free survival, and adverse events. QOL was compared before and 4 weeks after HN-PIT. There were no significant changes in all QOL assessment parameters after treatment with HN-PIT. The overall response rate was 89%, and safety was acceptable. For patients with unresectable LA/LR-HNC, HN-PIT provided good local control without decreasing the QOL. The addition of HN-PIT to conventional head and neck carcinoma treatment may lead to the prolongation of OS in head and neck carcinoma.

18 November 2020 in Cancers
Verified
Journal Article
Open access
PDF file
TMTakashi Matsuki
Takashi Matsuki
IOIsaku Okamoto
Isaku Okamoto
CFChihiro Fushimi
Chihiro Fushimi
HTHideaki Takahashi
Hideaki Takahashi
TOTakuro Okada
Takuro Okada
TYTaku Yamashita
Taku Yamashita
No real-world, long-term outcomes of immunotherapy with nivolumab for recurrent or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN) have yet been reported. Furthermore, the prognostic impact of the best overall response (BOR) of this therapy remains unclear. We conducted a multi-institutional cohort study of the long-term efficacy and safety of this therapy and investigated prognostic factors associated with survival. Further, we evaluated the relationship between BOR and survival. Median follow-up time was 25.9 months. Median overall survival (OS) was 9.6 months, and two-year survival rate was 25.0%. Median progression-free survival (PFS) was 3.7 months, and two-year PFS rate was 19.6%. BOR was assessed as complete response (CR) in 6%, partial response (PR) in 13%, stable disease (SD) in 30%, and progressive disease (PD) in 52% of the patients. Overall response rate was 18%, and disease control rate was 48%. For immune-related adverse events (irAEs), 38 irAEs were detected in 29 patients. On multivariate analysis, the development of irAEs was significantly associated with better OS and PFS. Better BOR was significantly associated with longer OS and PFS. These findings demonstrate the long-term efficacy and safety of nivolumab therapy for R/M SCCHN in a real-world setting. The magnitude of BOR and the development of irAEs might be useful surrogate markers of survival.

1 February 2022 in Case Reports in Oncology
Verified
Journal Article
Open access
PDF file
IOIsaku Okamoto
Isaku Okamoto
TOTakuro Okada
Takuro Okada
KTKunihiko Tokashiki
Kunihiko Tokashiki
KTKiyoaki Tsukahara
Kiyoaki Tsukahara
Photoimmunotherapy (PIT) targets and destroys tumor cells through irradiation with 690-nm red light after the administration of cetuximab sarotalocan sodium, which contains IRDye700DX bound to cetuximab. In Japan, PIT is a new treatment that is covered by insurance only for unresectable head and neck cancers. However, this treatment has conditional early approval. There have been no case reports describing the efficacy of this treatment in a real-world setting thus far. We report our experience with PIT for head and neck cancer. A 76-year-old man with laryngeal cancer underwent radiation therapy and surgery. Skin involvement in the right submandibular region was subsequently noted. We diagnosed local recurrence and performed PIT for this lesion. Partial response was achieved after the first PIT session, and progressive disease was diagnosed after the second session. Many aspects of PIT remain unclear and should, therefore, be clarified in further research. Despite this uncertainty, PIT may become an effective treatment strategy for head and neck cancer if the patient selection criteria are delineated.

2 March 2022 in In Vivo
Verified
Journal Article
Closed access
PDF file
IOIsaku Okamoto
Isaku Okamoto
TOTakuro Okada
Takuro Okada
KTKunihiko Tokashiki
Kunihiko Tokashiki
KTKiyoaki Tsukahara
Kiyoaki Tsukahara
Background: Head and neck photoimmunotherapy specifically destroys tumor cells by irradiating them with 690 nm red light after administering cetuximab sarotalocan sodium. The key point in the technique of photoimmunotherapy is to set the irradiation area precisely with a margin added to the target lesion while securing a safety zone with large vessels such as the internal carotid artery. Case Report: At our Institution, we performed photoimmunotherapy in combination with use of a navigation system on a male patient in his 70s with maxillary gingival carcinoma who had a recurrent lesion deep in the lateral pterygoid muscle. Three months after photoimmunotherapy, the superficial lesion had disappeared, the area of contrast within the lateral pterygoid muscle had improved, and the patient was deemed to have a complete response. Conclusion: The Navigation System was successfully used in combination with photoimmunotherapy. Additionally, this allowed the location of the internal carotid artery to be confirmed in real time.

26 February 2022 in Anticancer Research
Verified
Journal Article
Closed access
PDF file
TITatsuya Ito
Tatsuya Ito
IOIsaku Okamoto
Isaku Okamoto
KTKunihiko Tokashiki
Kunihiko Tokashiki
HSHiroki Sato
Hiroki Sato
TOTakuro Okada
Takuro Okada
KTKiyoaki Tsukahara
Kiyoaki Tsukahara
Background/Aim: This study investigated the expression and survival rates of programmed cell death ligand 1 using the tumor proportion score (TPS)and combined positive score (CPS) for recurrent/metastatic head and neck cancer administered nivolumab. Patients and Methods: Forty-seven patients with recurrent/metastatic head and neck cancer with a history of platinum-based chemotherapy who received nivolumab between June 1st, 2017, and January 31st, 2019 were included in this study. Results: TPS and CPS were strongly correlated (r=0.546). When the TPS was high (≥40%), overall and progression-free survival were significantly better. The median overall survival was 8.5 months, median progression-free survival was not reached, and the 1-year progression-free survival rate was 71.4%. However, there was no significant difference in overall and progression-free survival between the groups with high CPS (≥20). Conclusion: This is the first report to show a strong correlation between TPS and CPS. High TPS (40% or higher) may be used as a predictor of prognosis and efficacy. Further studies are warranted to determine the use of the CPS as a biomarker.