(HealthDay News) — For patients with newly diagnosed metastatic hormone-sensitive prostate cancer, addition of orteronel to androgen deprivation therapy (ADT) significantly improves progression-free survival, but not overall survival (OS), according to a study published online in the Journal of Clinical Oncology.

Neeraj Agarwal, MD, from the University of Utah Huntsman Cancer Institute in Salt Lake City, and colleagues randomly assigned patients with metastatic hormone-sensitive prostate cancer to ADT with orteronel or ADT with bicalutamide (638 and 641 patients, respectively). OS was compared as the primary objective, targeting a 33% improvement in median survival.

The researchers observed a significant improvement in progression-free survival (median, 47.6 vs 23.0 months; hazard ratio, 0.58; 95% confidence interval, 0.51 to 0.67) after a median follow-up of 4.9 years, and in prostate-specific antigen level at seven months, but not in OS (81.1 vs 70.2 months; hazard ratio, 0.86; 95% confidence interval, 0.72 to 1.02). In the experimental versus control arm, there were more grade 3/4 adverse events. Post-protocol life-prolonging therapy was received by 77.4 and 61.3% of patients in the control and experimental arms, respectively.

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“Although the approximately 11-month improvement in median OS with orteronel appears clinically meaningful, it did not reach the prespecified requirement for statistical significance,” the authors write.

The study was partially funded by Millennium Pharmaceuticals Inc. (Takeda Pharmaceutical Company LTD), the manufacturer of orteronel.

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