Bone-targeted Novel Cytotoxic Polybisphosphonate Conjugate in Castration-resistant Prostate Cancer: A Multicenter Phase 1 Study.

BACKGROUND: Osteodex (ODX) is a cytotoxic bone-targeting polybisphosphonate, intended for treatment of bone metastasis from castration-resistant prostate cancer (CRPC). The primary objective of this study was to describe the tolerability and toxicity of such treatment by defining its maximum tolerated dose (MTD) and dose-limiting toxicity (DLT).

PATIENTS AND METHODS: Twenty-eight patients with castration-resistant prostate cancer and confirmed bone metastasis were assigned to seven infusions of ODX every third week, divided in seven ascending dose cohorts.

RESULTS: No DLT's were observed and as pre-specified, the highest dose administered was defined as MTD. In total, 206 adverse events (AE) were recorded and 13,6% were classified as treatment-related, while none were serious or severe (SAE). No cumulative toxicity and no renal toxicity were recorded.

CONCLUSION: ODX was well tolerated, with few and mild side-effects and with apparent treatment efficacy in the highest dose cohort. Further clinical development is currently in progress.