Background

This observational study aims to assess the real‑world safety and efficacy of the existing treatment combination in patients with low‑volume metastatic hormone‑sensitive prostate cancer (mHSPC). In Japan, an optimal therapeutic strategy for low‑volume mHSPC has not yet been defined, creating a need for empirical data. Accordingly, the study seeks to validate the combination of darolutamide, androgen deprivation therapy, and docetaxel as used in routine clinical practice within a real‑world setting.

Study Design

The observational study will collect medical records of patients treated at multiple Japanese institutions from November 2024 through June 2031. Primary endpoints include the proportion of patients achieving PSA normalization at 12 months, as well as the incidence of adverse events (AE), serious adverse events (SAE), and adverse events of special interest (AESI), which are directly linked to treatment continuation. The study will be conducted without additional study visits, following the standard care pathway to minimize patient burden.

Mechanism of Action

Androgen deprivation therapy suppresses testosterone to slow cancer cell growth, while darolutamide blocks the androgen receptor to provide additional growth inhibition. Docetaxel is a microtubule inhibitor chemotherapy that halts cell division. Simultaneous use of the three agents creates a multi‑pronged attack targeting both hormone‑dependent and hormone‑independent tumor cells.

Market and Clinical Implications

Current mHSPC management relies on androgen deprivation therapy combined with an ARAT (androgen receptor‑targeted agent) or on docetaxel monotherapy as standard of care. If the triple regimen that includes darolutamide proves safe and effective in clinical practice, it could emerge as a new standard option for low‑volume mHSPC patients. This would expand the utilization of ARAT‑based therapies not only in Japan but across the broader Asian market.