Presentation of Domestic Phase II Clinical Trial Results for Angiosarcoma at ESMO 2025
We are pleased to announce that the detailed results of the domestic Phase II clinical trial of Boron Neutron Capture Therapy (BNCT) targeting angiosarcoma, jointly conducted by our company and CICS Co., Ltd. (Koto-ku, Tokyo), were presented at the poster session of the European Society for Medical Oncology (ESMO) Congress 2025, held in Germany on October 20, 2025 (local time) by Dr. Tairo Kashihara of the National Cancer Center Hospital.
Presentation Details
・Title: A Phase II Study of Boron Neutron Capture Therapy (BNCT) Using CICS-1 and SPM-011 in Patients with Unresectable Angiosarcoma
・Abstract Number: 1672P
Overview of the Clinical Trial
The primary objective of this trial was to evaluate the efficacy and safety of BNCT using CICS’s neutron irradiation system (CICS-1) and our boron-based drug (SPM-011) in patients with unresectable cutaneous angiosarcoma. The single-arm study※3 was conducted at the National Cancer Center Hospital in Japan with a total of 10 enrolled cases.
Trial Results
In this trial, the primary endpoint was set as the objective response rate※4 (ORR) based on central imaging review※5 within 90 days following BNCT administration. Among the 10 patients who received BNCT, three achieved partial response and two achieved complete response, resulting in an ORR of 50.0% (90% confidence interval※6: 22.2%–77.8%). The lower bound of the 90% confidence interval met the predefined threshold established during the trial design, thereby achieving the primary endpoint. Furthermore, no serious adverse events were observed, and no new safety concerns were identified.
Progression-free survival (PFS) was defined as the time from BNCT administration to the first confirmed disease progression or death. Over a follow-up period of 12.4 months, the median PFS was 6.3 months (95% confidence interval: 0.6 months to not estimable).
These results demonstrate the safety and efficacy of BNCT using CICS-1 and SPM-011, suggesting that BNCT may be a promising new treatment option for patients with unresectable cutaneous angiosarcoma.
Background
Currently, for unresectable angiosarcoma, especially in cases where chemoradiotherapy or conventional radiation therapy is not feasible, no effective treatment options for local control have been established. There is a strong clinical need for new therapies that offer higher local control rates. Considering this situation, our investigational BNCT drug SPM-011 was designated as an orphan drug※7 by the Ministry of Health, Labour and Welfare in December 2023 for the treatment of unresectable cutaneous angiosarcoma.
Based on the results of this trial, we plan to proceed with a regulatory approval application. We remain committed to advancing development so that BNCT can be offered as a new treatment option for patients.
※1 BNCT (Boron Neutron Capture Therapy):
Boron Neutron Capture Therapy is one sort of radiation therapy where a reaction between a boron containing drug and thermal neutrons occurs. As a new cancer treatment, the damage caused to the body is small and the effectiveness is expected to be high.
※２ Angiosarcoma:
Angiosarcoma is cancer that develops endothelial cells of blood vessels. It can occur anywhere in the body but mostly occurs in the skin.
※3 Single-arm trial:
A single-arm trial is a clinical trial in which all participants are treated with the same treatment without dividing them into multiple groups for comparison.
※4 Objective Response Rate:
The response rate is a measure used to evaluate the effectiveness of a treatment, representing the proportion of cases in a clinical trial that achieved partial response (tumor diameter reduction of 30% or more from baseline) or complete response (complete disappearance of the tumor, with no detectable tumor on examination).
※5 Central Imaging Review:
In pharmaceutical clinical trials, central imaging review refers to a method of evaluating efficacy and safety through an independent review organization (central review body), to ensure objectivity and consistency in image assessments.
※6 Confidence Interval:
A statistical range within which the true value of a measured effect is expected to lie with a given level of confidence (e.g. 90% CI: 22.2–77.8%).
※7 Orphan drug:
An orphan drug is a rare disease drug designated by the Minster of Health, Labour and Welfare and is given priority review. The number of target patients in Japan must be less than 50,000, a serious disease as target and no existing alternative suitable treatment or drug are also conditions. Furthermore, the drug’s effectiveness or safety must be expected significantly higher than existing drugs and a high medical need is required. There must be a theoretical justification for using the drug for the target disease and the development plan must be accepted as appropriate. An orphan drug is given preferential review for approval review process and research and development subsidies from the government.
