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The beneficial effect of intravenous zoledronic acid therapy following an acute stroke in rats.

PURPOSE: Changes of bone metabolism begin from the initial stages of stroke; therefore, early prevention of these changes has become important. The most appropriate target for preventive therapy is to restrict the profound increase in osteoclastic bone resorption that occur soon after stroke. Oral bisphosphonates, which selectively target osteoclasts and their precursors, are appropriate drugs, but dysphagia or drowsiness after acute stroke can make it difficult to easily administer these compounds to stroke patients. The intravenous (IV) administration of bisphosphonates is an alternative method that can overcome these limitations. In order to determine the effect of IV bisphosphonates at the initial stages of stroke for preventing bone loss, an experiment using ischemic stroke rats was conducted. METHODS: Female Sprague-Dawley rats (n = 100) were randomly divided into four separate groups; sham surgery and vehicle-treated group (sham-vehicle), stroke and vehicle-treated group (stroke-vehicle), stroke with low-dose zoledronic acid treatment group (stroke-low) and stroke with high-dose zoledronic acid treatment group (stroke-high). Permanent occlusion of the left middle cerebral artery was performed, resulting in right hemiplegia. The bone mineral density (BMD) of the 4th and 5th lumbar vertebrae and the femur on the stroke side were measured in vivo on the day before stroke and on the 10th and 21st day after stroke. The osteocalcin and carboxy-terminal telopeptide blood levels were measured on the 10th and 21st day after stroke. The BMD of the excised proximal tibia and the maximum load of femoral neck were measured on the 21st day after stroke. RESULTS: After 21 days of stroke, the BMD of the lumbar vertebrae, femur, and excised tibia and the maximum load of the femoral neck in the sham-vehicle, stroke-low, and stroke-high groups were significantly higher than those in the stroke-vehicle group (P < 0.05). The carboxy-terminal telopeptide levels in the sham-vehicle and stroke-high groups were significantly lower than those in the stroke-vehicle group (P < 0.05). CONCLUSION: The results suggest that IV zoledronic acid treatment might prevent bone loss during the initial stages of stroke.

Absorptiometry, Photon↗

[Treatment of Paget's disease of bone with zoledronic acid].

Bone pain and bone deformities are the most common manifestations of Paget's disease of bone, even if the diagnosis is nowadays most often made by chance following a routine measurement of serum alkaline phosphatase. Woven bone is formed following a marked increase in bone resorption due to a stimulation of osteoclast activity. Biphosphonates constitute the modern treatment of Paget's disease of bone. Tiludronate (Skelid), or better risedronate (Actonel), are administered orally every day during at least 2 months. Zoledronic acid (Aclasta), as a single 15-min 5 mg infusion, has been recently compared to risedronate, 30 mg/d orally for 2 months, in two randomized studies including 357 patients. Zoledronic acid had a superior therapeutic efficacy, as judged by its rapidity of action, the duration of the biochemical response and the percentage of responders. Thus, at 6 months, alkaline phosphatase levels were normalized in 89% of the patients in the zoledronic acid group as compared to 58% in the risedronate group. The most frequent side effect was a flu-like syndrome, observed in 10% of the patients. An adequate intake of calcium and vitamin D is recommended to avoid posttreatment hypocalcemia. The introduction of Aclasta should simplify and improve the therapeutic management of Paget's disease of bone.

Bone Density Conservation Agents↗

Combination of docetaxel, estramustine phosphate, and zoledronic acid in androgen-independent metastatic prostate cancer: efficacy, safety, and clinical benefit assessment.

OBJECTIVES: Docetaxel is an effective agent for the treatment of androgen-independent prostate cancer (AIPC). Its combination with estramustine phosphate (EMP) has shown promising results in AIPC but the toxicity remains considerable. In an effort to minimize toxicity, we designed an every-2-week docetaxel administration regimen with a 3-day low-dose EMP regimen. Patients with bone metastases also received zoledronic acid. METHODS: A total of 54 patients with AIPC received docetaxel at 45 mg/m2 and EMP (140 mg orally every 8 hours for nine doses) every 2 weeks. Zoledronic acid was administered at 4 mg every 28 days. RESULTS: Of the 49 assessable patients, 22 (45%, 95% confidence interval [CI] 31% to 60%) had a prostate-specific antigen response. Of 24 patients with measurable disease, 9 (38%, 95% CI 19% to 59%) had a response to therapy (one complete response and eight partial responses). The median time to progression was 4.4 months (95% CI 2.7 to 6), and overall survival was 13.3 months (95% CI 9 to 17.6). Toxicity was mild, with only 5 cases of grade 3 or 4 toxicity. The pain score improved by 1 point in 21 (54%) of 39 symptomatic patients, and 14 (40%) of 38 patients who used analgesics discontinued analgesic consumption by the end of treatment. CONCLUSIONS: The combination of an every-2-week regimen of docetaxel, EMP, and zoledronic acid is an effective, well-tolerated regimen that results in symptomatic improvement in a significant proportion of patients with AIPC.

Adenocarcinoma↗

The bisphosphonate zoledronic acid impairs Ras membrane [correction of impairs membrane] localisation and induces cytochrome c release in breast cancer cells.

Bisphosphonates are well established in the management of cancer-induced bone disease. Recent studies have indicated that these compounds have direct inhibitory effects on cultured human breast cancer cells. Nitrogen-containing bisphosphonates including zoledronic acid have been shown to induce apoptosis associated with PARP cleavage and DNA fragmentation. The aim of this study was to identify the signalling pathways involved. Forced expression of the anti-apoptotic protein bcl-2 attenuated bisphosphonate-induced loss of cell viability and induction of DNA fragmentation in MDA-MB-231 cells. Zoledronic acid-mediated apoptosis was associated with a time and dose-related release of mitochondrial cytochrome c into the cytosol in two cell lines. Rescue of cells by preincubation with a caspase-3 selective inhibitor and demonstration of pro-caspase-3 cleavage products by immunoblotting suggests that at least one of the caspases activated in response to zoledronic acid treatment is caspase-3. In both MDA-MB-231 and MCF-7 breast cancer cells, zoledronic acid impaired membrane localisation of Ras indicating reduced prenylation of this protein. These observations demonstrate that zoledronic acid-mediated apoptosis is associated with cytochrome c release and consequent caspase activation. This process may be initiated by inhibition of the enzymes in the mevalonate pathway leading to impaired prenylation of key intracellular proteins including Ras.

Apoptosis↗

Randomized, open label, prospective study on the effect of zoledronic acid on the prevention of bone metastases in patients with recurrent solid tumors that did not present with bone metastases at baseline.

OBJECTIVES: Bisphosphonates have been used successfully in the treatment of hypercalcemia and to reduce skeletal-related complications of bone metastases. Recent in vitro and in vivo evidence suggest that they may also have direct antitumor effects via induction of apoptosis, inhibition of the invasive potential of tumor cell lines in vitro, inhibition of angiogenesis, and reduction in tumor growth indirectly via effects on accessory cells. This is a randomized, open label, prospective study that examined the effect of preventive zoledronic acid treatment on the development of bone metastases in patients with recurrent solid tumors, without bone metastases at the time of randomization. METHODS: Forty patients with recurrent or metastatic advanced cancer, without bone metastases, were randomized into the trial to either receive zoledronic acid or no treatment. Patients were followed up until bone metastases were established. RESULTS: The percentage of patients being bone metastases free at 12 mo was 60% in the zoledronic acid and 10% in the control group (p<0.0005), while the percentages at 18 mo were 20% and 5% respectively (p=0.0002). CONCLUSIONS: The results have shown that bisphosphonates as adjuvant treatment might be useful for the prevention of bone metastases; however, there is need for blinded randomized data before such an approach would be confirmed. In the meantime preventive use of bisphosphonates in patients without any bone metastases should not be used outside the scope of a clinical trial.

Aged↗

[Therapeutic agents for disorders of bone and calcium metabolism: Zoledronic acid].

Intervenous (IV) bisphosphonates are used for cancer patients with hypercalcemia of malignancy (HCM) and breast cancer bone metastases (BM). Recently, zoledronic acid, the most potent third generation bisphosphonate, has been approved for both HCM and BM of broad tumors. It showed 850-fold stronger activity than pamidronate in bone resorption assay, and clinical efficacy against multiple cancer bone lesion has been confirmed in randomized clinical trials. Zoledronic acid becomes one of the most used bisphosphonate for cancer patients in the world, and the results of clinical trials for cancer treatment-induced bone loss or postmenopausal osteoporosis are now updating.

Bone Density↗

Clinical value of bone remodelling markers in patients with bone metastases treated with zoledronic acid.

BACKGROUND: Bisphosphonates have an established role in the treatment of bone metastases from a variety of solid tumours. The objective response to anti-resorptive treatment cannot be evaluated by imaging techniques. A number of bone remodelling markers have been associated with bone metastases status; among them, urine and serum levels of N-terminal telopeptide of collagen type I (NTx) seem to have the best diagnostic accuracy. However, serum NTx has not yet been properly evaluated. PATIENTS AND METHODS: Seventy-one consecutive patients with newly diagnosed skeletal metastases were enrolled in this prospective study. All of them were treated with zoledronic acid at 4 mg, every 3 or 4 weeks. Serum NTx and bone-isoform of alkaline phosphatase (BAP) were measured by enzyme-linked immunosorbent assays at baseline and every 2 months thereafter. RESULTS: At baseline, serum NTx and BAP levels were significantly higher in patients with blastic than lytic bone lesions and in those with multiple rather than few bone site involvement. Forty-seven patients were followed for a median period of 139 days. Zoledronic acid resulted in a significant NTx reduction at first and second post-treatment evaluations (mean reduction of 43% at first evaluation); thereafter, mean NTx levels remained suppressed. In contrast, BAP levels did not show any significant changes. Bone disease progression resulted in a significant NTx elevation by an average of 69%. The initial response of NTx to zoledronic acid was correlated with the long-term clinical outcome of bone disease: patients with an initial NTx elevation had a significantly higher rate of bone disease progression compared to those with an initial NTx decline (66.7% versus 18.8%, p=0.001). Extraskeletal disease or bone irradiation did not influence NTx response. CONCLUSION: Serum NTx appears to be a useful marker in monitoring patients with skeletal metastases, as it is correlated with the type and bulk of bone disease and reflects bone disease progression. It is also useful in monitoring bisphosphonate therapy, while the initial response to this therapy seems to bear a prognostic significance for bone disease outcome.

Aged↗

Docetaxel and zoledronic acid in patients with metastatic hormone-refractory prostate cancer.

OBJECTIVE: To evaluate the safety and efficacy of combined docetaxel-zoledronic acid treatment in patients with metastatic hormone-refractory prostate cancer (HRPC), as bisphosphonates are reported have a synergistic antitumoral effect when combined with taxanes. PATIENTS AND METHODS: Between January 2001 and June 2003, 14 patients with HRPC were treated; their mean (range) age was 71 (57-86) years and mean prostate-specific antigen (PSA) level 202 (6-489) ng/mL. Five patients had had previous chemotherapy (cyclophosphamide in two, mitoxantrone-prednisolone in three). The response criteria were the Karnofsky performance status, a positive response in mean daily analgesic consumption (defined as a decrease by more than half), decreased serum PSA (by more than half) at 8 weeks, blood transfusion, bone scan at 6 months, skeletal-related events and survival. RESULTS: Patients received a mean (range) of 7.3 (6-10) cycles of therapy; there was no reported drug-related toxicity and all patients stayed at home for their treatment. Only three patients required a blood transfusion and no bone fractures were reported. At 2 months, six patients requiring analgesic drugs decreased their consumption by more than half (anti-inflammatory, paracetamol, narcotics) and eight had a reduction in PSA by more than half; of these eight with a PSA response at 2 months, six had biochemical progression with a mean delay of 6.2 (3-11) months. At 6 months, five patients had disease progression on bone scan. Nine patients had chemo-naïve hormone-refractory prostate cancer; three had biochemical progression at 2 months and two of these had progression on their bone scan. Two patients died at 7 and 15 months of follow-up; the mean follow-up was 10.2 (6-15) months. Using Kaplan-Meier plots, biochemical progression-free survivals were five of 14 at 6 months and two of 14 at 12 months; overall survival was 12 of 14 at 6 and 12 months. CONCLUSION: Docetaxel-zoledronic acid therapy is safe and decreased the serum PSA by more than half at 2 months in more than half the patients. Prospective randomized trials are needed to assess this new approach.

Aged↗

Zoledronic acid cooperates with a cyclooxygenase-2 inhibitor and gefitinib in inhibiting breast and prostate cancer.

Biphosphonates (BPs) are widely used to inhibit osteoclastic activity in malignant diseases such as bone metastatic breast and prostate carcinoma. Recent studies reported that BPs could also cause a direct antitumor effect, probably due to their ability to interfere with several intracellular signalling molecules. The enzyme cyclooxygenase-2 (COX-2) and the epidermal growth factor receptor (EGFR) play an important role in the control of cancer cell growth and inhibitors of COX-2 and EGFR have shown antitumor activity in vitro and in vivo in several tumor types. We, and others, have previously shown that EGFR and COX-2 may be directly related to each other and that their selective inhibitors may have a cooperative effect. In the present study we have evaluated the combined effect of zoledronic acid, the most potent nitrogen-containing BP, with the COX-2 inhibitor SC-236 and the selective EGFR-tyrosine kinase inhibitor gefitinib, on breast and prostate cancer models in vitro and in xenografted nude mice. We show that combination of zoledronic acid with SC-236 and gefitinib causes a cooperative antitumor effect accompanied by induction of apoptosis and regulation of the expression of mitogenic factors, proangiogenic factors and cell cycle controllers both in vitro and in xenografted nude mice. The modulatory effect on protein expression and the inhibitory effect on tumor growth is much more potent when the three agents are used together. Since studies are ongoing to explore the antitumor effect of zoledronic acid, our results provide new insights into the mechanism of action of these agents and a novel rationale to translate this feasible combination treatment strategy into a clinical setting.

Animals↗

A prospective randomized controlled clinical trial of zoledronic acid for bone metastases.

In this study, we assessed the safety, tolerability, and effectiveness of two therapeutic regimens relating to the frequency of zoledronic acid (ZOL) infusion. Sixty adult patients with bone metastases were randomly assigned to two study groups. The first group (group A) received 4 mg ZOL every two weeks, and the second group (group B) received 4 mg ZOL every four weeks. Assessment measures included C-telopeptide (CTX) rate, the Greek Brief Pain Inventory (GBPI), the linear analogue scale assessment (LASA) of quality of life, and biochemical markers. Assessments were made at weeks 12, 24, 36, and 48. Clinical endpoints included effective decrease in bone resorption markers, pain relief and improvement of mobility status. The follow-up period was 48 weeks. No statistically significant differences between groups A and B were found in overall profile of biochemical markers, Eastern Cooperative Oncology Group (ECOG) performance status, and GBPI score at the end of the follow-up period. Assessment of bone metastases revealed a slight difference between the two groups, however this difference was not statistically significant. These findings indicate that administering zoledronic acid at four rather that two weeks has no significant impact on overall outcome.

Aged↗

[Phase II randomized clinical trail of zoledronic acid in treating metastatic bone pain of malignancy].

BACKGROUND & OBJECTIVE: Bone metastases are the prevailing reason for pain in patients with malignancies, which seriously affect their life quality. Zoledronic acid, the third generation of bisphosphonates, can inhibit the activity of osteoclasts and relieve pain. This study was to evaluate the efficacy and safety of zoledronic acid in treating metastatic bone pain for patients with malignancies. METHODS: A multi-center, randomized, double-blind, and prospective trail was conducted. Patients with metastatic bone pain were randomized to receive zoledromic acid plus monnitol, or pamidronate plus monnitol as positive control. RESULTS: From Oct. 2003 to Oct. 2004, 216 patients with metastatic bone pain were randomized into 2 groups: 109 in zoledromic acid group, and 107 in pamidronate group. There was no significant difference in pain intensity (PI) between zoledromic acid group and pamidronate group before treatment (6.0+/-1.1 vs. 6.0+/-1.3, P=0.938), 7 days after treatment (3.7+/-1.99 vs. 4.1+/-2.0, P=0.119), and 14 days after treatment (3.2+/-2.0 vs. 3.7+/-2.4, P=0.129). The differences in complete response (CR) rate, partial response (PR) rate, and total response rate between the 2 groups were not significant (10.4% vs. 9.5%, 69.8% vs. 69.5%, 88.7% vs. 85.7%, P>0.05). Time to CR was significantly shorter in zoledromic acid group than in pamidronate group [(7.0+/-2.2) days vs. (9.5+/-2.6) days, P=0.033]; the differences in time to PR, duration of CR, and duration of PR between the 2 groups were not significant [(4.9+/-2.6) days vs. (5.0+/-2.5) days, P=0.908; (13.2+/-1.80) days vs. (14.0+/-0.0) days, P=0.155; and (13.4+/-1.9) days vs. (12.8+/-2.8) days, P=0.127]. The main adverse events were fever, nausea, vomiting, and general malaise. The occurrence and severity of adverse events were similar between the 2 groups. CONCLUSION: Zoledromic acid is effective and safe in treating metastatic bone pain of patients with malignancy, which is similar to pamidranate.

Adult↗

Cytotoxic activity of the third-generation bisphosphonate zoledronic acid in acute myeloid leukemia.

The third-generation bisphosphonate zoledronic acid (ZOL) has recently been shown to be active against human tumour and leukemic cell lines. The purpose of this study was to evaluate the antileukemic potential of ZOL in acute myeloid leukemia (AML). We determined the lethal concentration 50% (LC 50) using the WST-1 assay of ZOL as being 287.9 microg/ml after 24 h and 108.3 microg/ml after 96 h in HL 60 cells and to be 382.4 and 43.2 microg/ml, respectively, in nine samples from patients with AML. The ZOL induced inhibition of proliferative activity of HL 60 cells could not be abrogated by the hematopetic growth factors G-CSF and GM-CSF. ZOL was found to by cytotoxic in HL 60 cells without activation of caspase 3. ZOL was not cross resistant with cytarabine as shown by the linear correlation of LC 50s. Both agents, however, exerted an additive cytotoxicity as revealed by isobologram-analysis and combination index. These data warrant further investigation of ZOL in the treatment of AML.

Acute Disease↗

The nitrogen-containing bisphosphonate, zoledronic acid, influences RANKL expression in human osteoblast-like cells by activating TNF-alpha converting enzyme (TACE).

UNLABELLED: Bisphosphonates are used to prevent osteoclast-mediated bone loss. Zoledronic acid inhibits osteoclast maturation indirectly by increasing OPG protein secretion and decreasing transmembrane RANKL expression in human osteoblasts. The decreased transmembrane RANKL expression seems to be related to the upregulation of the RANKL sheddase, TACE. INTRODUCTION: Bisphosphonates (BPs) exhibit high affinity for hydroxyapatite mineral in bone and are used extensively to treat malignancy-associated bone disease and postmenopausal bone loss by inhibiting osteoclast (OC)-mediated bone resorption. MATERIALS AND METHODS: We examined the effect of the most potent nitrogen-containing BP available, zoledronic acid (ZOL), on the expression of RANKL and osteoprotegerin (OPG), critical factors in the regulation of OC formation and activation, in primary osteoblast (OB)-like cells derived from human bone, using flow cytometry, ELISA, semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), in situ immunofluorescence staining, and Western blotting. RESULTS: Our studies show that ZOL, while not significantly affecting RANKL or OPG gene expression, markedly increased OPG protein secretion and reduced transmembrane RANKL protein expression in OB-like cells. The reduction in transmembrane RANKL expression was preceded by a marked increase in the expression of the metalloprotease-disintegrin, TNF-alpha converting enzyme (TACE). In addition, the decreased transmembrane expression of RANKL could be partially reversed by a TACE inhibitor, TAPI-2. CONCLUSIONS: Our studies indicate that ZOL, in addition to its direct effects on mature OCs, may inhibit the recruitment and differentiation of OCs by cleavage of transmembrane RANKL in OB-like cells by upregulating the sheddase, TACE.

ADAM Proteins↗

Short-term zoledronic acid treatment increases bone mineral density and marrow clonogenic fibroblast progenitors after allogeneic stem cell transplantation.

Although osteoporosis is a relatively common complication after allogeneic stem cell transplantation, the role of bisphosphonates in its management has not yet been completely established. Thirty-two patients who underwent allogeneic stem cell transplantation were prospectively evaluated for bone mineral density (BMD) at the lumbar spine (LS) and femoral neck (FN) after a median period of 12.2 months. Then, 15 of the patients with osteoporosis or rapidly progressing osteopenia (bone loss > 5%/yr) received three monthly doses of 4 mg zoledronic acid iv. Fifteen patients were followed up without treatment, and all 30 patients were reevaluated after 12 months for BMD and bone turnover markers. By using enriched mesenchymal stem cells in the colony-forming units fibroblast (CFU-F) assay, we evaluated the osteogenic stromal lineage. This procedure was performed in both groups of patients at study entry and after 12 months. The average BMD loss was 3.42% at LS and 3.8% at FN during a 1-yr longitudinal evaluation in 32 patients. Subsequently, BMD increased at both LS and FN (9.8 and 6.4%, respectively) in the zoledronic acid-treated cohort. Hydroxyproline excretion decreased, and serum bone-specific alkaline phosphatase increased significantly, whereas serum osteocalcin increase did not reach the limit of significance. A significant increase in CFU-F growth in vitro was induced by in vivo zoledronic acid administration. In the untreated group, no significant change was observed in bone turnover markers, LS BMD (-2.1%), FN BMD (-2.3%), and CFU-F colony number. In conclusion, short-term zoledronic acid treatment consistently improved both LS and FN BMD in transplanted patients who were at high risk for fast and/or persistent bone loss, partly by increasing the osteogenic progenitors in the stromal cell compartment.

Adolescent↗

Safety and pain palliation of zoledronic acid in patients with breast cancer, prostate cancer, or multiple myeloma who previously received bisphosphonate therapy.

An open-label study conducted in community centers assessed the safety of zoledronic acid 4 mg intravenously over 15 minutes every 3-4 weeks as treatment of bone metastases in patients with multiple myeloma, breast cancer, or prostate cancer with and without previous bisphosphonate exposure. Adverse events (AEs), pain, and quality-of-life (QOL) scores were recorded, and serum creatinine (SCr) levels were measured before each infusion. Of 638 patients, 415 patients (65%) had received prior bisphosphonate therapy. Fatigue, nausea, and arthralgia were the most frequent AEs. Nausea was more common in bisphosphonate-naive patients. SCr levels increased notably in 6.6% of patients: 7.7% of patients who received prior bisphosphonate therapy and 4.5% of bisphosphonate-naive patients. Treatment was delayed because of SCr-level increases in 1.4% of patients with prior bisphosphonate exposure and 0.4% of bisphosphonate-naive patients. SCr-level increases and treatment delays did not correlate with duration of prior bisphosphonate therapy. There was a trend towards more treatment discontinuations in patients with prior bisphosphonate exposure compared with bisphosphonate-naive patients. Pain scores decreased from baseline; total QOL scores remained constant. The results of this study suggest that, with proper SCr-level monitoring, cancer patients with bone metastases who have previously received intravenous bisphosphonate treatment can be safely converted to zoledronic acid therapy.

Aged↗

A randomized, double-blind, placebo-controlled trial of intravenous zoledronic acid in the treatment of thalassemia-associated osteopenia.

Beta-thalassaemia major is associated with low bone mass and fractures. We conducted a 2 year randomized controlled trial of zoledronic acid 4 mg administered intravenously every 3 months or placebo in the treatment of beta-thalassaemia-associated osteopenla. We recruited 23 subjects from 2 university hospitals with a T score of less than -1.0 at either the lumbar spine or hip, and 23 subjects completed the study (17 M, 6 F). Treatment groups did not differ significantly with respect to bone mineral density (BMD), age, height, weight and body mass index (BMI) at baseline. BMD was assessed at baseline, 12 months and 24 months by dual-energy X-ray absorptiometry (DXA) at the lumbar spine, femoral reek, total hip and total body. After two years average lumbar spine BMD was 8.9% greater (95%CI 2.3-15.5%, P = 0.011), average femoral neck BMD was 9.1% greater (95%CI 5.5-12.7%, P < 0.0001), average total hip BMD was 9.6% greater (95%CI 6.5-12.6%, P < 0.0001) and average total body BMD was 4.7% greater (95%CI 2.7-6.8%, P < 0.0001) in the treated group compared to placebo. The absolute change in BMD from baseline to 2 years and the annualized rate of change of BMD was significantly greater in treated patients at all four sites. Age, gender, height, weight and BMI did not interact with the effect of treatment and so unadjusted data was used. The serum total ALP decreased 45% by 12 months (P = 0.004) and urinary deoxypyridinoline/creatinine ratio decreased 47% by 3 months (NS). We conclude that zoledronic acid (4 mg i.v. 3 monthly) suppresses bone turnover and increases BMD in beta-thalassaemia-associated osteopenia.

Adolescent↗

Manipulation of the anabolic and catabolic responses with OP-1 and zoledronic acid in a rat critical defect model.

UNLABELLED: Bone repair involves both anabolic and catabolic responses. We hypothesized that anabolic treatment with OP-1 (BMP-7) and anti-catabolic treatment with zoledronic acid could be synergistic. In a rat critical defect, this combination therapy produced significant increases in new bone volume and strength. INTRODUCTION: When used to augment bone healing, osteogenic protein 1 (OP-1/BMP-7) and other BMPs stimulate the anabolic response, inducing osteoblast recruitment, differentiation, and bone production. However, BMPs can also upregulate catabolism by direct stimulation of osteoclasts and indirectly by osteoblasts through RANKL/RANK. We hypothesized that if such osteoclastic upregulation were modulated by zoledronic acid (ZA), the combination of OP-1 and ZA should produce increased new bone over OP-1 alone. MATERIALS AND METHODS: Rats with a surgically induced 6-mm femoral critical size defect were separated into five dosing groups: Carrier, Carrier + ZA, OP-1, OP-1 + ZA, and OP-1 + ZA administered 2 weeks after surgery (2W). Carrier +/- 50 microg OP-1 was placed in the defect, and 0.1 mg/kg ZA or saline was administered subcutaneously. Bone repair was analyzed by radiographs, QCT, mechanical testing, histology, and histomorphometry. RESULTS: Carrier alone and Carrier ZA groups did not unite by 8 weeks. Radiological union occurred in all OP-1 groups but was tenuous in some animals treated with OP-1 alone. BMC was increased by 45% in the OP-1 ZA group and 96% in the OP-1 ZA 2W group over OP-1 alone (p < 0.01). Callus volume increased over OP-1 alone by 45% and 86% in the OP-1 ZA and OP-1 ZA 2W groups, respectively (p < 0.01). The increased callus volume in the OP-1 ZA 2W group translated to increases in strength of 107% and stiffness of 148% (p < 0.05). BFR was not significantly different between OP-1 groups regardless of ZA treatment. CONCLUSIONS: ZA treatment significantly increased the BMC, volume, and strength of OP-1-mediated callus in a critical size defect in rats at 8 weeks. Thus, modulation of both anabolic and catabolic responses may optimize the amount and mineral content of callus produced, which could be of clinical benefit in obtaining bone union.

Animals↗

Zoledronic acid mediates Ras-independent growth inhibition of prostate cancer cells.

Zoledronic acid (ZOL), the most potent known bisphosphonate, is clinically efficacious against advanced prostate cancer, although the molecular mechanism by which bisphosphonates prevent prostate cancer cell growth remains unknown. Because Ras is the most thoroughly characterized member of the small G-proteins involved in the regulation of many cellular functions including several oncogenic pathways, the aim of this study was to clarify whether Ras is the molecular target of ZOL in prostate cancer cells. The prostate cancer cell lines PC-3, DU145, and LNCaP were used. Cell proliferation was determined by a modified MTT assay. Geranylgeranyol (GGOH) and famesol (FOH) were used as analogues of geranylgeranyl-pyrophosphate and farnesyl-pyrophosphate, respectively. Changes in expression and/or membrane localization of Ras, Rap1, and phosphorylated MAPK were evaluated by Western blotting. ZOL mediated growth inhibition of prostate cancer cells in a dose- and time-dependent manner. The ZOL-induced growth inhibitory effect was circumvented by the addition of GGOH. In contrast, FOH did not reverse the growth inhibitory effect of ZOL. The amount of membrane-anchored Ras was clearly independent of ZOL-mediated growth inhibition. Unexpectedly, ZOL induced N- and H-Ras expression of the cytosolic fraction. Ras does not appear to be the molecular target for ZOL-induced growth inhibition. Prevention of geranylgeranylation rather than farnesylation is an important therapeutic target in prostate cancer.

Blotting, Western↗