Denosumab is really effective in the treatment of osteoporosis secondary to hypogonadism in prostate carcinoma patients? A prospective randomized multicenter international study.

Abstract

Introduction: Osteoporosis is a complication of androgen deprivation therapy (ADT) in men with prostate carcinoma. The best defense against osteoporosis in prostate cancer is to identify patients with a high risk for fracture during the first clinical visit, select an effective anti-osteoporosis agent, and advise the patient to change his lifestyle and diet to prevent further bone loss. New agents include denosumab, a human monoclonal antibody that inhibits the RANK ligand (RANKL). RANKL promotes the formation, activity, and survival of osteoclasts and, thus, supports the breakdown of bone.

Purpose: This is a multicenter, randomized, double-blind prospective study on use of denosumab versus alendronate in the therapy of secondary osteoporosis related to ADT in prostate cancer patients in three European countries (Italy, France, Switzerland).

Patients and methods: In this 24-month observation study we enrolled 234 patients with diagnosis of osteoporosis underwent ADT for prostate cancer. All patients aged ≥55 years and had a dual-energy X-ray absorptiometry (DEXA) T-score <-1.0 (hip or spine, measured within last 2 years) and ≥ 1 fragility fracture. Patients were randomly assigned 1:1 to receive denosumab 60 mg subcutaneously every 6 months or alendronate (70 mg weekly) for 2 years. All patient received supplemental vitamin D (600 IU per day) and supplemental calcium to maintain a calcium intake of 1200 mg per day. Effectiveness of therapy in both groups (denosumab group and alendronate group) was assessed by changes in bone turnover markers (BTMs), Bone Mineral Density (BMD), fracture incidence, Visual Analogue Scale (VAS) score for back pain, and Short Form-8 (SF-8TM) health survey score for health-related quality of life (HRQoL). Percent changes from baseline in BTMs and BMD were assessed using the paired t test; a P-value 0.05). Mean changes in BMD at final follow-up differed significantly between two groups. BMD changes at the lumbar spine at 24 months were 5.6% with denosumab vs -1.1% with alendronate (P<0.001). New vertebral fractures developed in fewer patients in the denosumab group than in the alendronate group during the 24-month period, although this difference was not significant (P=0.10). Back pain significantly (P<0.001) improved from baseline at all time points during the study in both study groups. SF-8 health survey scores significantly improved following treatment with both drugs. Incidence of adverse drug reactions were similar in both groups.

Conclusion: In our study denosumab and alendronate showed similar clinical efficacy in the therapy of ADT-related osteoporosis in men with prostate carcinoma; both drugs provided significant improvements in back pain and general health conditions. Denosumab showed significant increase of BTMs and BMD than alendronate with lower rate of new vertebral fractures.