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Updated: Jun 10, 2026
A Bioluminescent and Fluorescent Orthotopic Syngeneic Murine Model of Androgen-dependent and Castration-resistant Prostate Cancer
Published on: March 6, 2018
Efficacy of S-1 in patients with castration-resistant prostate cancer: a phase II study
Hideyuki Akaza1, Isao Ikemoto, Mikio Namiki
1Department of Urology and Andrology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan. akazah@md.tsukuba.ac.jp
Objectives:
This study was conducted to evaluate the efficacy and safety of S-1, an oral fluoropyrimidine derivative, in Japanese patients with castration-resistant prostate cancer (CRPC). The primary endpoint was prostate-specific antigen (PSA) response.
Methods:
In this open-label phase II study, S-1 was started at a dose of 80, 100 or 120 mg daily based on body surface area (BSA) for 28 days, followed by 14 days of rest. Patients with histological proof of prostate cancer refractory to hormonal therapies were eligible. Patients who received prior chemotherapy were excluded. All patients provided written informed consent. To observe 20% confirmed PSA response, 33 assessable patients were needed. Treatment was continued until disease progression or the development of intolerable toxicity.
Results:
A total of 35 eligible patients were enrolled. The median number of treatment cycles was 3. PSA response was observed in 8 patients (22.9%, 90% CI 11.9-37.5), including 3 in which (8.6%) the PSA level normalized. The median overall survival was 25.4 months. The most common treatment-related grade 3 toxicity was anorexia (14.3%). There was no death during the study.
Conclusion:
S-1 monotherapy is active against castration-resistant prostate cancer and has acceptable toxicity.
