Bisphosphonates Can Prevent Skeletal Complications of Malignant Bone Disease from Prostate Cancer and Renal Cell Carcinoma

Mechanism of Action, Pharmacokinetic and Pharmacodynamic Profile, and Clinical Applications of Nitrogen-containing Bisphosphonates

Nitrogen-containing bisphosphonates (nBPs) are bone-specific agents that inhibit farnesyl diphosphate synthase. nBPs’ strong affinity for bone, and not for other tissues, makes them potent inhibitors of bone resorption and bone remodeling activity, with limited potential for side-effects in non-skeletal tissues. Five nBPs are currently approved in the United States. The primary indications are for treatment of osteoporosis (alendronate, ibandronate, and risedronate) and treatment/prevention of skeletal-related events (SREs) in multiple myeloma and breast and prostate cancer patients (ibandronate, pamidronate, and zoledronic acid). nBPs are the most efficacious drugs available for these diseases, reducing osteoporotic fracture risk by 50–60% in persons with low bone mass or prior osteoporotic fracture, and SREs by one-third in cancer patients. The absorbed nBP dose for cancer patients is from seven to ten times that in osteoporosis patients. nBPs are unique in that they first exert profound pharmacodynamic effects long after their blood levels reach zero. Current pharmacokinetic studies indicate that approximately half of any nBP dose reaches the skeleton, with an early half-life of ten days, and a terminal half-life of about ten years. Practical study design limitations and theoretical considerations suggest that both the half-life and the amount of nBP retained in the skeletons of patients on long-term nBP therapy are substantially overestimated by extrapolation directly from current pharmacokinetic data. In fact, the amount of nBP being released from skeletal tissues of long-term-treated patients, particularly in osteoporosis patients, becomes insufficient to maintain full pharmacodynamic efficacy relatively soon after dosing is interrupted.

Adjuvant Effect of IV Clodronate on the Delay of Bone Metastasis in High-Risk Prostate Cancer Patients: A Prospective Study

PURPOSE

High-risk prostate cancer patients undergoing treatment often experience biochemical recurrence. The use of bisphosphonates as an adjuvant treatment delays skeletal events, yet whether or not bisphosphonates also delay metastastic development remains to be determined.

MATERIALS AND METHODS

A total of 140 high-risk prostate cancer patients who were undergoing definitive treatment and who had clinically organ-confined disease and who suffered from biochemical recurrence were administered intravenous (IV) clodronate. The patients were treated with a radical retropubic prostatectomy (RP) or curative radiotherapy (RTx). Upon androgen deprivation therapy initiation, tri-monthly IV clodronate was added to the treatment to prevent bone demineralization. Twenty-six out of 60 operated cases and 45 out of 80 irradiated cases received bisphosphonate. The length of time until the first bone metastasis was recorded and analyzed.

RESULTS

No statistical difference was found for the type of primary treatment (RP or RTx) on the time to the first bone metastasis (95% confidence interval [CI], 0.40 to 2.43; p=0.98). However, there was a clear advantage favoring the group that received bisphosphonate (p<0.001). The addition of bisphosphonate delayed the appearance of the first bone metastasis by seven-fold (95% CI, 3.1 to 15.4; p<0.001).

CONCLUSION

Treatment with tri-monthly IV clodronate delayed the time to the first bone metastasis in high-risk prostate cancer patients who were experiencing an increase in the prostate specific antigen level after definitive treatment.

Zoledronic acid use in cancer patients: more than just supportive care?

Bone is the most common site for metastasis from solid tumors, and the majority of patients will develop bone metastases during the natural course of their disease. Bisphosphonates are an effective treatment for preventing skeletal-related events in patients with bone metastases and may preserve functional independence and quality of life. Although several bisphosphonates have been investigated in patients with solid tumors, only zoledronic acid (ZOL) is approved by the US Food and Drug Administration and the European Medicines Agency for preventing skeletal-related events in patients across a broad range of solid tumors. In addition, bisphosphonates, notably ZOL, prevent cancer treatment-induced bone loss in breast and prostate cancer patients who are receiving endocrine therapy. It also has been demonstrated that ZOL directly and indirectly inhibits cancer cell growth in vitro and growth and tumorigenesis in animal model systems. These properties may produce clinically meaningful benefits. In recent clinical studies in patients with cancer, ZOL improved overall and prolonged disease-free survival. Ongoing clinical trials in patients with solid tumors will provide further insight into the potential of ZOL to prevent distant metastases and improve survival.

Efficacy of clodronate, pamidronate, and zoledronate in reducing morbidity and mortality in cancer patients with bone metastasis: a meta-analysis of randomized clinical trials

BACKGROUND

Complications from skeletal-related events (SREs) constitute a challenge in the care of patients with metastatic bone disease (MBD) that originated from any type of malignancy.

OBJECTIVE

The purpose of this article was to compare the efficacy of clodronate, pamidronate, and zoledronate with that of placebo in reducing morbidity and overall mortality in cancer patients with MBD.

METHODS

MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched (from inception to January 2009) to retrieve randomized clinical trials that evaluated the bisphosphonates of interest. The search included articles published in English, French, Italian, Portugese, and Spanish. Patients with a definite (ie, biopsy-proven) diagnosis of MBD were included in the analysis. We extracted and combined data from studies that reported the number of patients with SREs and mortality data. A random-effects, meta-analytic model was applied in all calculations. The Jadad scale was used to assess the quality of study reporting.

RESULTS

The literature search identified 62 potential full-text studies; 44 of these studies were excluded and 18 were evaluated. The mean (SD) quality of reporting of the included studies was 57.8% (22.6%), or 2.89/5 (1.1/5). Each of the 3 drugs was found to be more effective than placebo in preventing all SREs in cancer patients with MBD. The relative risk of developing SREs was 0.70 (95% CI, 0.61-0.81; N = 1211) for zoledronate, 0.81 (95% CI, 0.73-0.91; N = 2251) for pamidronate, and 0.87 (95% CI, 0.75-1.00; N = 681) for clodronate. However, no clear advantage of one drug over the others was observed (CIs overlapped substantially). None of the bisphosphonates was more beneficial than placebo in reducing the number of deaths in the course of the trials (P = NS).

CONCLUSION

Clodronate, pamidronate, and zoled-ronate were associated with reductions in morbidity in cancer patients with MBD with regard to preventing SREs, but were not associated with a reduction in overall mortality.

Guidance on the use of bisphosphonates in solid tumours: recommendations of an international expert panel

Bisphosphonates (BP) prevent, reduce, and delay cancer-related skeletal complications in patients, and have substantially decreased the prevalence of such events since their introduction. Today, a broad range of BP with differences in potency, efficacy, dosing, and administration as well as approved indications is available. In addition, results of clinical trials investigating the efficacy of BP in cancer treatment-induced bone loss (CTIBL) have been recently published. The purpose of this paper is to review the current evidence on the use of BP in solid tumours and provide clinical recommendations. An interdisciplinary expert panel of clinical oncologists and of specialists in metabolic bone diseases assessed the widespread evidence and information on the efficacy of BP in the metastatic and nonmetastatic setting, as well as ongoing research on the adjuvant use of BP. Based on available evidence, the panel recommends amino-bisphosphonates for patients with metastatic bone disease from breast cancer and zoledronic acid for patients with other solid tumours as primary disease. Dosing of BP should follow approved indications with adjustments if necessary. While i.v. administration is most often preferable, oral administration (clodronate, IBA) may be considered for breast cancer patients who cannot or do not need to attend regular hospital care. Early-stage cancer patients at risk of developing CTIBL should be considered for preventative BP treatment. The strongest evidence in this setting is now available for ZOL. Overall, BP are well-tolerated, and most common adverse events are influenza-like syndrome, arthralgia, and when used orally, gastrointestinal symptoms. The dose of BP may need to be adapted to renal function and initial creatinine clearance calculation is mandatory according to the panel for use of any BP. Subsequent monitoring is recommended for ZOL and PAM, as described by the regulatory authority guidelines. Patients scheduled to receive BP (mainly every 3-4 weeks i.v.) should have a dental examination and be advised on appropriate measures for reducing the risk of jaw osteonecrosis. BP are well established as supportive therapy to reduce the frequency and severity of skeletal complications in patients with bone metastases from different cancers.