Toremifene Increases Bone Mineral Density in Men Receiving Androgen Deprivation Therapy for Prostate Cancer: Interim Analysis of a Multicenter Phase 3 Clinical Study

Purpose

We evaluated the effects of toremifene on bone mineral density, a surrogate for fracture risk, in men receiving androgen deprivation therapy for prostate cancer.

Materials and Methods

In an ongoing, multicenter, phase 3 fracture prevention study 1,392 men 50 years or older with prostate cancer receiving androgen deprivation therapy were randomized to 80 mg toremifene per day or placebo. Bone mineral density of the lumbar spine, total hip and femoral neck was assessed using dual energy x-ray absorptiometry. In this planned interim analysis of the first 197 subjects we compared bone mineral density changes from baseline to month 12 between the placebo and toremifene groups.

Results

Compared with the placebo group men in the toremifene group had significant increases in bone mineral density at each evaluated skeletal site. Lumbar spine bone mineral density decreased 0.7% in the placebo group and increased 1.6% in the toremifene group (between group comparison p <0.001). Total hip bone mineral density decreased 1.3% in the placebo group and increased 0.7% in the toremifene group (p = 0.001). Femoral neck bone mineral density decreased 1.3% in the placebo group and increased 0.2% in the toremifene group (p = 0.009). Between group differences in the change in bone mineral density from baseline to month 12 were 2.3%, 2.0% and 1.5% for the lumbar spine, total hip and femoral neck, respectively.

Conclusions

Toremifene significantly increased hip and spine bone mineral density in men receiving androgen deprivation therapy for prostate cancer. The effect of toremifene on the fracture risk is being assessed in the ongoing randomized, controlled trial.

Key Words: prostatic neoplasms, gonadotropin-releasing hormone, orchiectomy, osteoporosis, androgen antagonists

Abbreviations and Acronyms: ADT, androgen deprivation therapy, BMD, bone mineral density, DXA, dual energy x-ray absorptiometry, GnRH, gonadotropin-releasing hormone, SERM, selective estrogen receptor modulator