Managing bone health with zoledronic acid: a review of randomized clinical study results

Dosing related effects of zoledronic acid on bone markers and creatinine clearance in patients with multiple myeloma and metastatic breast cancer

Zoledronic acid (Zol) is frequently used for the treatment of bone disease in patients with multiple myeloma and breast cancer with metastasis to bone. Therefore, there is also an interest in finding the optimal dosing regimen to optimize effects, minimize side effects and reduce costs. In our phase II clinical trial we investigated the effect of Zol treatment on the serum levels of the bone markers collagen type 1 cross-linked C-telopeptide (CTX) and bone specific alkaline phosphatase (bALP) as well as on creatinine clearance (kidney function) in response to dosing and duration of treatment for each individual patient.

METHODS

We enrolled 30 multiple myeloma (MM) and 30 breast cancer (BC) patients whereof 10 of each had never received bisphosphonate and 20 had received at least six prior Zol treatments.

RESULTS

We found that Zol treatment strongly reduced CTX (Spearman's correlation, rs = -0.59, p = 0.0007) and bALP (Spearman's correlation, rs = -0.51, p = 0.0042) in MM patients while only CTX (Spearman's correlation, rs = -0.42, p = 0.024) was significantly affected in BC patients. Multiple linear regression analyses done on the entire cohort showed that the average time between each dose of Zol had the strongest impact on CTX (p < 0.001) and bALP (p = 0.011) levels while the total accumulated number of Zol infusions had a less pronounced effect on CTX levels (p = 0.015). In contrast, multiple linear regression analysis showed that the total number of Zol infusions had a strong negative impact on kidney function (p = 0.014) while the average time between each dose of Zol had no significant impact.

CONCLUSION

Thus, if MM and BC patients are not treated regularly every month with Zol bone turnover is not fully suppressed, while prolonged treatment with zoledronic acid compromises kidney function. We believe that these data significantly contribute to the knowledge needed to find the optimal Zol treatment schedule.

Is retention of zoledronic acid onto bone different in multiple myeloma and breast cancer patients with bone metastasis?

Zoledronic acid (Zol) is used to treat bone disease in both multiple myeloma (MM) and breast cancer patients with bone metastasis (BC). However, bones of MM and BC patients show a difference in retention of the bisphosphonate used for bone scintigraphy. Therefore, we hypothesized that disease-specific factors may differently influence Zol retention in MM and BC patients. We tested this hypothesis in an investigator initiated phase II clinical trial in which we compared the whole-body retention (WBrt) of Zol in a cohort of 30 multiple myeloma (MM) and 30 breast cancer (BC) (20 Zol naive and 40 with six or more previous administrations). On average, 62% of the administered Zol was retained in the skeleton of both MM and BC patients and independently of the number of treatments. WBrt of Zol did not correlate with cross-linked C-telopeptide (CTX) levels, but linear regression analyses showed that WBrt of Zol correlated with bone-specific alkaline phosphatase (bALP) levels in BC (p = 0.001), and with CTX/bALP in Zol naive MM patients (p = 0.012). Especially in BC patients, WBrt correlated with age (p = 0.014) independently of kidney function. In MM patients WBrt was found to primarily correlate with the extent of bone disease (p = 0.028). Multivariate linear regression analyses of the entire cohort pointed out that WBrt of Zol was best predicted by age (p < 0.000), osseous lesions (p < 0.001), and the preceding Zol dosing (p < 0.005) (r(2)  = 0.97). Comparing bone scintigrams with CT/X-ray images showed a poor correlation between sites of active bone disease and binding of scintigraphy bisphosphonate in 36% of MM patients and in 13% of BC patients. We conclude that WBrt of Zol is primarily determined by two non-disease related factors and only one disease related, but that there may be differences in retention or drug delivery at individual sites of bone disease between MM and BC patients. In order to find the optimal dosing of Zol, these observations should be taken into account.

Oral care and the use of bone-targeted agents in patients with metastatic cancers: A practical guide for dental surgeons and oncologists

BACKGROUND

Bone-targeted agents such as bisphosphonates and the RANKL antibody have revolutionised the care of patients with bone metastases. There has, however been increasing concern about the oral health of these patients and in particular osteonecrosis of the jaw (ONJ), especially with the increasing use of these agents at higher potencies for greater periods of time.

METHODS

A review of the published data in PubMed and meeting abstracts was performed to examine incidence, risk factors, pathogenesis, clinical course and management of osteonecrosis of the jaw with focus on cancer patients treated with bone-targeted agents (BTA) for bone metastases. This manuscript takes the most frequent and pertinent questions raised by oncologists, dentists and oral and maxillofacial surgeons and tries to give a pragmatic overview of the literature.

RESULTS

The incidence of ONJ varies depending on types of bone-targeted agents, duration of treatment and additional risk factors. The causes and pathogenesis of ONJ is not fully elucidated, however bone-targeted therapy induced impaired bone remodelling, microtrauma secondary to jaw activity, and oral bacterial infection seem to be important factors. Since the treatment options for ONJ are limited and not well established, preventive strategies have to be included in patients management.

CONCLUSIONS

Many unanswered questions remain about the optimal oral care of patients receiving bone-targeted agents. Prospective data collection will remedy this and help to provide practical guidelines for the management and treatment of those patients that require dental intervention.