Comparative prospective, double-blind, multicenter study of the efficacy of tiludronate and etidronate in the treatment of Paget's disease of bone

Drug treatment strategies for Paget's disease: relieving pain and preventing progression

INTRODUCTION

Paget's disease of bone (PDB) is a focal bone disorder caused by a marked dysregulation of osteoblasts and osteoclasts in basic multicellular units, leading to abnormal and disorganized deposition of collagen fibers (the so-called "woven bone"). Therefore, pagetic bones are increased in size, and at increased risk for bone pain, deformities, fractures, osteoarthritis, and, more rarely, neoplastic degeneration.

AREAS COVERED

In this review we revise the available information concerning the pharmacological treatment of PDB.

EXPERT OPINION

PDB progresses slowly within the affected skeletal sites and, if untreated, often leads to bone overgrowth, with bone pain, deformity and a likely increased risk of complications. Thus, the primary goal of treatment is the restoration of a normal bone turnover, in order to relieve bone pain or other symptoms and possibly prevent the complications. PDB long remained a poorly treatable disorder until the discovery of antiresorptive agents such as calcitonin first and bisphosphonates (BPs) later. With the recent development of potent intravenous BPs like zoledronate, allowing a better control of disease activity over the long term with a single infusion, has contributed to a marked improvement of the clinical management of this invalidating disorder.

Bisphosphonates in the management of Paget's disease

The first clinical use of bisphosphonates was in Paget's disease of bone (PDB) when disodium etidronate was found to be effective at suppressing metabolic activity of the disease. Subsequently, PDB became a testing ground for many bisphosphonates using changes in alkaline phosphatase (ALP) as the primary outcome measure in clinical trials. Bisphosphonates are now considered to be the treatment of choice for PDB since they are highly effective at suppressing the elevations in bone turnover that are characteristic of the disease. Short term studies have shown that treatment with alendronate and risedronate can promote formation of lamellar bone in affected sites and improve x-ray appearances in some patients. Bisphosphonates have also been shown to improve bone pain in PDB and within the bisphosphonates, zoledronic acid (ZA) is most likely to give a favourable pain response. Many patients with PDB do not have pain however, even when there is increased metabolic activity and more research is needed to find out why this is the case. The effects of bisphosphonates on complications of PDB such as deformity, pathological fractures and deafness have not been adequately studied since most clinical trials have been short term and have not collected information on these important outcomes. The PRISM and PRISM-EZ studies investigated the long-term effects of bisphosphonates in patients with established PDB using a treat-to-target approach and showed that intensive bisphosphonate therapy aimed at normalising ALP was no more effective than symptom directed treatment with bisphosphonates at preventing complications of PDB. The Zoledronate in the Prevention of Paget's Disease (ZiPP) trial, which is currently in progress, seeks to determine whether early intervention with this potent bisphosphonate might be effective in preventing disease progression. Should the ZiPP study yield positive results, genetic testing coupled to prophylactic bisphosphonate therapy might represent a new indication for these highly effective inhibitors of bone resorption in future years.

Bisphosphonates-much more than only drugs for bone diseases

α,α-Bisphosphonates (BPs) are well established in the treatment of bone diseases such as osteoporosis and Paget's disease. Their successful application originates from their high affinity to hydroxyapatite. While the initially appreciated features of BPs are already beneficial to many patients, recent developments have further expanded their pleiotropic applications. This review describes the background of the interactions of BPs with bone cells that form the basis of the classical treatment. A better understanding of the mechanism behind their interactions allows for the parallel application of BPs against bone cancer and metastases followed by palliative pain relief. Targeted therapy with bone-seeking BPs coupled with a diagnostic agent in one particle resulted in theranostics which is also described here. For example, in such a system, BP moieties are bound to contrast agents used in magnetic resonance imaging or radionuclides used in positron emission tomography. In addition, another example of the pleiotropic function of BPs which involves targeting the imaging agents to bone tissues accompanied by pain reduction is presented in this work.

Bisphosphonates for Paget's disease of bone in adults

BACKGROUND

Bisphosphonates are considered to be the treatment of choice for people with Paget's disease of bone. However, the effects of bisphosphonates on patient-centred outcomes have not been extensively studied. There are insufficient data to determine whether reducing and maintaining biochemical markers of bone turnover to within the normal range improves quality of life and reduces the risk of complications.

OBJECTIVES

To assess the benefits and harms of bisphosphonates for adult patients with Paget's disease of bone.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, ISI Web of Knowledge and trials registers up to March 2017. We searched regulatory agency published information for rare adverse events.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of bisphosphonates as treatment for Paget's disease in adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results, extracted data and assessed studies for risk of bias. We used standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

We included 20 trials (25 reports, 3168 participants). Of these, 10 trials (801 participants) compared bisphosphonates (etidronate, tiludronate, ibandronate, pamidronate, olpadronate, alendronate, risedronate, zoledronate) versus placebo, seven compared two bisphosphonates (992 participants), one trial compared a bisphosphonates with a bisphosphonate plus calcitonin (44 participants), and two studies, the largest trial (1331 participants) and its interventional extension study (502 participants), compared symptomatic treatment and intensive treatment where the goal was to normalise alkaline phosphatase.Most studies were assessed at low or unclear risk of bias. Six of 10 studies comparing bisphosphonates versus placebo were assessed at high risk of bias, mainly around incomplete outcome data and selective outcome reporting.Participant populations were reasonably homogeneous in terms of age (mean age 66 to 74 years) and sex (51% to 74% male). Most studies included participants who had elevated alkaline phosphatase levels whether or not bone pain was present. Mean follow-up was six months.Bisphosphonates versus placeboBisphosphonates tripled the proportion (31% versus 9%) of participants whose bone pain disappeared (RR 3.42, 95% confidence interval (CI) 1.31 to 8.90; 2 studies, 205 participants; NNT 5, 95% CI 1 to 31; moderate-quality evidence). This result is clinically important. Data were consistent when pain change was measured as any reduction (RR 1.97, 95% CI 1.29 to 3.01; 7 studies, 481 participants).There was uncertainty about differences in incident fractures: 1.4% fractures occurred in the bisphosphonates group and none in the placebo group (RR 0.89, 95% CI 0.18 to 4.31; 4 studies, 356 participants; very low-quality evidence).None of the studies reported data on orthopaedic surgery, quality of life or hearing thresholds.Results regarding adverse effects and treatment discontinuation were uncertain. There was a 64% risk of mild gastrointestinal adverse events in intervention group participants and 48% in the control group (RR 1.32, 95% CI 0.91 to 1.92; 6 studies, 376 participants; low-quality evidence). The likelihood of study participants discontinuing due to adverse effects was slightly higher in intervention group participants (4.4%) than the control group (4.1%) (RR 1.01, 95% CI 0.41 to 2.52; 6 studies, 517 participants; low-quality evidence). Zoledronate was associated with an increased risk of transient fever or fatigue (RR 2.57, 95% CI 1.21 to 5.44; 1 study, 176 participants; moderate-quality evidence).Bisphosphonates versus active comparatorMore participants reported pain relief with zoledronate than pamidronate (RR 1.30, 95% CI 1.10 to 1.53; 1 study, 89 participants; NNT 5, 95% CI 3 to 11) or risedronate (RR 1.36, 95% CI 1.06 to 1.74; 1 study, 347 participants; NNT 7, 95% CI 4 to 24; very low quality evidence). This result is clinically important.There was insufficient evidence to confirm or exclude differences in adverse effects of bisphosphonates (RR 1.05, 95% CI 0.95 to 1.76; 2 studies, 437 participants; low-quality evidence) and treatment discontinuation (2 studies, 437 participants) (RR 2.04, 95% CI 0.43 to 9.59; 2 studies, 437 participants; very low-quality evidence).Intensive versus symptomatic treatmentThere was no consistent evidence of difference to response in bone pain, bodily pain or quality of life in participants who received intensive versus symptomatic treatment.Inconclusive results were observed regarding fractures and orthopaedic procedures for intensive versus symptomatic treatment (intensive treatment for fracture: RR 1.84, 95% CI 0.76 to 4.44; absolute risk 8.1% versus 5.2%; orthopaedic procedures: RR 1.58, 95% CI 0.80 to 3.11; absolute risk 5.6% versus 3.0%; 1 study, 502 participants; low-quality evidence).There was insufficient evidence to confirm or exclude an important difference in adverse effects between intensive and symptomatic treatment (RR 1.05, 95% CI 0.79 to 1.41; low-quality evidence).There was insufficient evidence to confirm or exclude an important difference of risk of rare adverse events (including osteonecrosis of the jaw) from the regulatory agencies databases.

AUTHORS' CONCLUSIONS

We found moderate-quality evidence that bisphosphonates improved pain in people with Paget's disease of bone when compared with placebo. We are uncertain about the results of head-to-head studies investigating bisphosphonates. We found insufficient evidence of benefit in terms of pain or quality of life from intensive treatment. Information about adverse effects was limited, but serious side effects were rare, and rate of withdrawals due to side effects was low.

[Paget's disease of bone: Diagnostic and therapeutic updates]

Paget's disease of bone is the second most common metabolic bone disease after osteoporosis. Its pathogenesis is not yet clearly understood. Geographic distribution and epidemiological variations suggest a role of genetic and environmental factors in its pathophysiology. The frequency of the Paget's disease of bone increases with age. Its discovery can be fortuitous. Prognosis mainly depends on the occurrence of complications involving bones and joints, neurological, cardiovascular or metabolic systems. Treatment of symptomatic forms currently relies on bisphosphonates that have transformed its prognosis.

Paget Disease of Bone

The current understanding of Paget disease of bone (PDB) has vastly changed since Paget described the first case in 1877. Medical management of this condition remains the mainstay of treatment. Surgical intervention is usually only used in fractures through pagetic bone, need for realignment to correct deformity in major long bones, prophylactic treatment of impending fractures, joint arthroplasty in severe arthritis, or spinal decompression in cases of bony compression of neural elements. Advances in surgical technique have allowed early return to function and mobilization. Despite medical and surgical intervention, a small subset of patients with PDB develops Paget sarcoma.

Paget's Disease of Bone: A Review of Epidemiology, Pathophysiology and Management

Paget's disease of bone is a common disorder which may affect one or many bones. Although many patients are asymptomatic, a variety of symptoms and complications may occur. Fortunately, effective pharmacologic therapy, primarily with potent bisphosphonates, is now available to treat patients with complications or symptoms. This review of Paget's disease of bone will include epidemiology and pathophysiology, complications and clinical findings, indications for treatment, and the drugs currently available to treat this condition.

Treatment of Paget's disease of bone

Paget's disease of bone is the paradigm of bone focal distortion with accelerated bone turnover. Over the years, a number of different drugs have been used to control its activity but, since biphosphonates were introduced for the treatment of the disease, they have become the preferred treatment. This review will update the therapeutic indications, available drugs and therapeutic response monitoring.

Bisphosphonates in Paget's disease

Paget's disease is the best example of a common high turnover bone disease. A review of the early use of bisphosphonates in the treatment of this condition shows that many of the fundamental therapeutic issues were identified using drugs which by today's standards were far from ideal. Over the succeeding decades there has been a steady increase in potency culminating in the introduction of intravenous zoledronic acid which is capable of inducing long term remissions which were unthinkable when bisphosphonates were first introduced.

Randomized trial of intensive bisphosphonate treatment versus symptomatic management in Paget's disease of bone

Bisphosphonates are widely regarded as the treatment of choice for Paget's disease of bone (PDB) because of their potent inhibitory effects on bone turnover, but the effects of bisphosphonate therapy on symptoms and complications of PDB have been little studied. Here we report the results of a randomized trial that compared the effects of symptomatic treatment with intensive bisphosphonate therapy in a cohort of 1324 patients with PDB who were followed up for a median of 3 years (range 2 to 5 years). The symptomatic treatment group was treated only if they had pagetic bone pain, for which they were first given analgesics or anti-inflammatory drugs, followed by bisphosphonates if they did not respond. The intensive group received repeat courses of bisphosphonates irrespective of symptoms with the aim of reducing and maintaining serum alkaline phosphatase (ALP) levels within the normal range. The endpoints were fracture, orthopedic surgery, quality of life, bone pain, and hearing thresholds. Serum ALP levels were significantly lower in the intensive treatment group than in with the symptomatic treatment group within 4 months of commencing treatment and remained lower throughout the study (p < .001). There was no difference between the groups in quality of life (as assessed by the SF36 questionnaire), in overall bodily pain, or in pagetic bone pain. Hearing thresholds, as assessed by audiometry did not change significantly and did not differ between the treatment groups. Clinical fractures occurred in 46 of 661 patients (7.0%) in the intensive treatment group compared with 49 of 663 patients (7.4%) in the symptomatic treatment group, and orthopedic surgery was required in 50 of 661 patients (7.3%) in the intensive treatment group and in 55 of 663 patients (8.3%) in the symptomatic treatment group. These differences were not significant. Subgroup analyses of patients with elevated ALP levels at baseline and those who did or did not receive bisphosphonates during the study yielded similar results to those in the study group as a whole. We conclude that striving to maintain normal ALP levels with intensive bisphosphonate therapy confers no clinical advantage over symptom-driven management in patients with established PDB. Neither management strategy had a significant beneficial impact on pain or quality of life (Clinical trial registration number ISRCTN12989577).

Current options for the treatment of Paget's disease of the bone

Paget’s disease of bone (PDB) is a chronic bone remodelling disorder characterized by increased osteoclast-mediated bone resorption, with subsequent compensatory increases in new bone formation, resulting in a disorganized mosaic of woven and lamellar bone at affected skeletal sites. This disease is most often asymptomatic but can be associated with bone pain or deformity, fractures, secondary arthritis, neurological complications, deafness, contributing to substantial morbidity and reduced quality of life. Neoplastic degeneration of pagetic bone is a relatively rare event, occurring with an incidence of less than 1%, but has a grave prognosis. Specific therapy for PDB is aimed at decreasing the abnormal bone turnover and bisphosphonates are currently considered the treatment of choice. These treatments are associated with a reduction in plasma alkaline phosphatase (ALP) activity and an improvement in radiological and scintigraphic appearance and with a reduction in bone pain and bone deformity, Recently, the availability of newer, more potent nitrogen-containing bisphosphonates has improved treatment outcomes, allowing a more effective and convenient management of this debilitating disorder.

Management of patients with Paget's disease: a consensus document of the Belgian Bone Club

Paget's disease of bone (PDB) is a potentially crippling condition. Pain, fracture, spinal stenosis, nerve entrapment, vascular steal syndrome, secondary osteoarthritis, bone deformity, dental problems, deafness, excessive bleeding during orthopaedic surgery, rare sarcomatous degeneration, and hypercalcaemia constitute complications that may impair the quality of life. The therapeutic approach varies from symptomatic (analgesics, anti-inflammatory drugs) to more specific drugs such as increasingly potent bisphosphonates. Studies such as the PRISM study should in the future help to determine the superiority or not of aggressive treatment over symptomatic treatment in the prevention of complications. Various oral and/or intravenous (i.v.) bisphosphonates have been tested and are currently on the market. The most recently available nitrogen-containing bisphosphonate, i.v. zoledronic acid, is the most potent therapy available for the treatment of PDB. Its therapeutic efficacy, its long-term effect on biologic activity and its good tolerance currently supports its use as a first-line therapeutic option in patients suffering from PDB.

Pathogenesis and management of Paget's disease of bone

Paget's disease of bone is a common disease characterised by focal areas of increased bone turnover, affecting one or several bones throughout the skeleton. Paget's disease is often asymptomatic but can be associated with bone pain and other complications such as osteoarthritis, pathological fracture, bone deformity, deafness, and nerve compression syndromes. Genetic factors have an important role in this disease, and mutations have been identified in four genes that cause Paget's disease and related syndromes. The most important of these is Sequestosome 1 (SQSTM1), which is a scaffold protein in the nuclear factor kappaB (NFkappaB) signalling pathway. Patients with SQSTM1 mutations have severe Paget's disease of bone and a high degree of penetrance with increasing age. Environmental factors also contribute. Most research has focused on paramyxovirus infection as a possible trigger, but evidence for this notion is conflicting. Other potential triggers include deficiency of dietary calcium and repetitive mechanical loading of the skeleton. Medical management of Paget's disease of bone is based on giving inhibitors of osteoclastic bone resorption, and bisphosphonates are the treatment of first choice. Bisphosphonate therapy is primarily indicated for patients who have bone pain arising from increased metabolic activity in affected bones. Bisphosphonate therapy is highly effective at reducing bone turnover, and it has been shown to heal radiological lesions and restore normal histology; however, the long-term effects of bisphosphonates on disease progression have not been adequately studied. No firm evidence as yet exists to show that bisphosphonates can prevent the development of complications of Paget's disease of bone, and further work is needed to address the effects of treatment on long-term clinical outcome.

A review of Paget's disease of bone with a focus on the efficacy and safety of zoledronic acid 5 mg

BACKGROUND

Paget's disease of bone, the second most common metabolic bone disease in the United States, is characterized by localized areas of excessive bone resorption coupled with accelerated bone formation, resulting in new bone that is less structurally organized and is weaker than normal bone. Complications of Paget's disease can include bone pain, osteoarthritis, skeletal deformity, hearing loss, and fractures. The objective of this review is to provide a comprehensive overview of current standards of treatment in Paget's disease.

SCOPE

A review of literature from 1974 to 2007 was performed on topics such as epidemiology, etiology, treatment of Paget's disease of bone, and bisphosphonates.

FINDINGS

Paget's disease affects an estimated 2-7% of persons of age 55 years or older in North America and western Europe. Antiresorptive treatment with bisphosphonates is the standard treatment, but there may be limitations to oral therapy. Intravenous pamidronate is efficacious and has long been available, but its use is hindered by an impractical recommended dosing regimen of 30 mg IV over 4 h for three consecutive days. In two identical, double-blind, 6-month trials, 96% of patients treated with a one-time intravenous treatment of zoledronic acid 5 mg achieved therapeutic response, compared with 74% treated with 60 days of daily oral treatment with risedronate 30 mg (p < 0.001). One limitation of this review is that historical data are not reviewed in the same level of detail as newer treatments, because recent advances in pharmacotherapy of Paget's disease have reduced the clinical utility of the older drugs.

CONCLUSION

The etiology of Paget's disease is unclear, but some evidence suggests genetic and viral components. Bisphosphonates restore normal bone turnover and relieve bone pain, but oral formulations may be limited by complicated dosing regimens and poor gastrointestinal absorption. The bisphosphonate, zoledronic acid is administered as a single intravenous infusion and offers antiresorptive efficacy and longer-lasting remission.

[Therapy of Paget's disease]

Paget's disease of bone, an often undiagnosed metabolic bone disease, can lead to dramatic skeletal changes with enlargement and bowing of the affected bones. The etiology of this localized bone disease has not yet been determined. Genetic factors and viral infections may be involved. Recently, the treatment options for Paget's disease have been greatly improved due to the development of potent bisphosphonates. These agents inhibit osteoclastic bone resorption and allow the suppression of the excessive bone turnover in Paget's disease. This leads to a stabilization of affected bones and to symptomatic improvements. Treatment should be initiated early after diagnosis to limit the extent of damage. The article gives an overview of recent perspectives on epidemiology, diagnosis, and treatment of the disease according to the new German guidelines for the diagnosis and therapy of Paget's disease.

Zoledronic Acid

The third-generation, nitrogen-containing bisphosphonate zoledronic acid (Aclasta) is approved in the EU for the treatment of Paget's disease of bone. Results of well designed trials show that a single intravenous dose of zoledronic acid 5 mg is effective and well tolerated in the treatment of Paget's disease of bone. A single intravenous dose of zoledronic acid was associated with a significantly higher therapeutic response rate and a more rapid reduction in bone turnover than that achieved with 60 days of oral risedronic acid. Moreover, biochemical remission was sustained after 24 months of follow-up in zoledronic acid recipients. Preliminary results suggest that zoledronic acid is a cost-effective option in Paget's disease of bone. Thus, zoledronic acid is an important first-line treatment for Paget's disease of bone.

[Treatment of Paget's disease of bone: importance of the zoledronic acid]

Paget's disease is a localised monostotic or polyostotic bone disease of unknown origin. It may be caused by a slow viral infection and/or genetic factors. It is characterised by increased bone remodelling and an initially excessive osteoclastic bone resorption, followed by a secondary increase in osteoblastic activity, leading to replacement of the normal bone by a disorganized, enlarged, and weakened osseous structure prone to deformities and fractures. The disease may be diagnosed by radiography, scintigraphy and biochemical tests. The primary aim of treatment is to reduce pain and risk of developing long-term complications. Potent antiresorptive drugs are now available, which control the increased bone remodelling and have led to a dramatic improvement in treatment. Zoledronic acid, a new generation of bisphosphonates, has the advantage of great potency and long duration of remission and a short infusion time.

Medical management of Paget's disease of bone: indications for treatment and review of current therapies

Treatment with a potent bisphosphonate is indicated in patients with Paget's disease who have symptoms likely to respond to reduced bone turnover at pagetic sites. In asymptomatic patients with active disease at sites susceptible to local progression and late complications, treatment is also recommended. Biochemical remission is achievable in a majority of patients with pamidronate, alendronate, risedronate, or zoledronic acid. Indications for medical treatment of active Paget's disease of bone include symptoms referable to sites of the disease such as bone pain, joint pain, and neurological complications; elective surgery at an active pagetic site to reduce intraoperative blood loss from highly vascular bone; management of rare instances of immobilization hypercalcemia with polyostotic disease; and presence of disease activity in asymptomatic patients at sites at risk for future complications to limit progression and possibly lower that risk. The treatment of choice is a potent nitrogen-containing bisphosphonate, including oral alendronate or risedronate or intravenous pamidronate or zoledronic acid. Etidronate and tiludronate are less potent and are second-line choices. Recent data with zoledronic acid indicate that a single infusion of 5 mg is associated with normalization of serum alkaline phosphatase in 89% of patients and a prolonged biochemical remission, making it the most effective therapy available to date. Side effect profiles with alendronate and risedronate include esophageal irritation in a minority of patients. Intravenous pamidronate and zoledronic acid may induce an acute phase reaction with fever and flu-like symptoms with the first dose, primarily in patients who are treatment naïve to nitrogen-containing bisphosphonates. Calcium and vitamin D repletion are mandatory with these potent anti-osteoclast therapies to avoid hypocalcemia. Acquired resistance to etidronate and pamidronate has been reported in some patients, leading to lesser reductions in bone turnover and shorter periods of remission, but substitution with a different bisphosphonate provides a more robust response. It is not known whether resistance to other bisphosphonates in Paget's disease occurs.

Paget's disease of bone

Paget's disease of bone is a focal disorder of bone remodeling accompanied initially by an increase in bone resorption, followed by a disorganized and excessive formation of bone, leading to pain, fractures and deformities. It exhibits a marked geographical variation in its prevalence. In Brazil it predominantly affects persons of European descent. The majority of the reported cases of the disease in Brazil are from Recife, owing to its peculiar mixed European colonization over approximately four centuries. The etiology is complex and involves both genetic and environmental factors. The disease is often asymptomatic and diagnosis is usually based on biochemical markers of bone turnover, radionuclide bone scan and radiological examination. Bisphosphonates, in particular zoledronic acid, are regarded as the treatment of choice for Paget's disease of bone.

Guidelines for diagnosis and management of Paget's disease of bone in Japan

We here propose guidelines for the diagnosis and management of Paget's disease of bone (PDB) in Japan. These guidelines provide basic information on the epidemiology, pathophysiology, clinical signs and symptoms, diagnosis, indications for treatment, and available therapy, including orthopedic surgery. PDB is a chronic disorder characterized by focal abnormalities of bone turnover. The characteristic feature of PDB is excessive osteoclastic bone resorption coupled to increased and disorganized bone formation. The most common symptom of PDB is pain in involved bones. The most serious complication of PDB is malignant bone or soft-tissue tumor. PDB is uncommon in Japan; our survey in 2003 found 169 patients with PDB. The prevalence of PDB in Japan is 0.15/100 000; in patients aged 55 years or more, the proportion reaches 0.41/100 000. A careful medical history and physical examination are essential for the diagnosis. The diagnosis of PDB is based on finding the typical features on radiographs. Bone scintigraphy and measurement of serum alkaline phosphatase are sensitive means of screening for PDB. Since PDB is a rare disease in Japan, bone biopsy is quite often used to exclude bone metastases. The only evidence-based indication for treatment of PDB is pain in involved bones. In Japan, etidronate and calcitonin are approved by the Ministry of Health, Labour and Welfare for treating PDB, but currently risedronate is also under development for treating PDB in Japan. Indications for surgical intervention in PDB include unstable fractures, osteoarthritis, malignant soft-tissue tumor, osteosarcoma, and bone deformity.

Comparison of a single infusion of zoledronic acid with risedronate for Paget's disease

BACKGROUND

The advent of bisphosphonates advanced therapy for Paget's disease, but more effective and convenient agents are needed to increase adherence. Zoledronic acid, a bisphosphonate administered as a single intravenous infusion, might meet these needs.

METHODS

In two identical, randomized, double-blind, actively controlled trials of 6 months' duration, we compared one 15-minute infusion of 5 mg of zoledronic acid with 60 days of oral risedronate (30 mg per day). The primary efficacy end point was the rate of therapeutic response at six months, defined as a normalization of alkaline phosphatase levels or a reduction of at least 75 percent in the total alkaline phosphatase excess. The results of the studies were pooled.

RESULTS

At six months, 96.0 percent of patients receiving zoledronic acid had a therapeutic response (169 of 176), as compared with 74.3 percent of patients receiving risedronate (127 of 171, P<0.001). Alkaline phosphatase levels normalized in 88.6 percent of patients in the zoledronic acid group and 57.9 percent of patients in the risedronate group (P<0.001). Zoledronic acid was associated with a shorter median time to a first therapeutic response (64 vs. 89 days, P<0.001). Higher response rates in the zoledronic acid group were consistent across all demographic, disease-severity, and treatment-history subgroups and with changes in other bone-turnover markers. The physical-component summary score of the Medical Outcomes Study 36-item Short-Form General Health Survey, a measure of the quality of life, increased significantly from baseline at both three and six months in the zoledronic acid group and differed significantly from those in the risedronate group at three months. Pain scores improved in both groups. During post-trial follow-up (median, 190 days), 21 of 82 patients in the risedronate group had a loss of therapeutic response, as compared with 1 of 113 patients in the zoledronic acid group (P<0.001).

CONCLUSIONS

A single infusion of zoledronic acid produces more rapid, more complete, and more sustained responses in Paget's disease than does daily treatment with risedronate.

Zoledronic acid-related angiogenesis modifications and survival in advanced breast cancer patients

The proven antiangiogenic activity of zoledronic acid, a third-generation bisphosphonate widely used in bone metastatic cancer patients, led us to investigate if the vascular endothelial growth factor (VEGF)-related zoledronic acid modifications are correlated with survival advantages in advanced breast cancer patients. Forty-two consecutive breast cancer patients with scintigraphic and radiographic evidence of bone metastases were treated with a single infusion of 4 mg zoledronic acid before anticancer chemotherapy. The patients were prospectively evaluated for circulating levels of VEGF and interferon-gamma (IFN-gamma) just before and at 1, 2, 7, and 21 days after zoledronic acid infusion. Afterward, clinical outcome was prospectively monitored. The basal serum VEGF median levels were significantly decreased at each time point, but the major reduction was recorded 21 days after the infusion. In particular, 25 patients of 42 (59.5%) experienced a reduction of at least 25% in the VEGF circulating levels. In contrast, no statistically significant modifications of the IFN-gamma serum levels were recorded. We stratified patients on the basis of this VEGF reduction 21 days after the infusion. No differences in patient features were recorded between those with or without the VEGF reduction. The analysis of survival showed that patients with a reduction in the VEGF circulating levels had a longer time to first skeletal-related event (p = 0.0002), time to bone progression disease (p = 0.0024), and time to performance status worsening (p = 0.0352) than those without the VEGF reduction. No statistically significant differences were recorded in terms of overall survival and time to visceral progression. This study confirms that zoledronic acid could have an in vivo antiangiogenic property and that the VEGF modifications may represent a surrogate marker able to predict time to first skeletal-related event, time to bone progression disease, and time to worsening of performance status.

Maladie de Paget, exploration et surveillance

Paget's disease is a progressive bone disease, characterized by bone hypertrophy and increased bone resorption. The pain and deformity that characterize its clinical course are not simple to assess, but it has a characteristic radiographic appearance. In most cases, treatment can be monitored through biological markers of bone turnover. Total alkaline phosphatase is the best marker and measurement of collagen breakdown products is useful in difficult cases. The goal of treatment is the normalization of these biological markers, to prevent complications of the disease.

Maladie de Paget, prise en charge thérapeutique

Bisphosphonates, potent anti-osteoclastic agents, are nowadays the first-line therapy for Paget's disease of bone. Solid evidence about efficacy and the risk/benefit ratio favor tiludronate and risedronate for oral administration and pamidronate for intravenous administration. Treatment is always intermittent, with the frequency of therapeutic sequences depending on the specific drug and the quality and duration of response. Treatment response is assessed by the extent of the reduction of biochemical markers of bone turnover, especially plasma total alkaline phosphatase. The goal of the treatment is to induce full remission, that is, normal levels of alkaline phosphatase. Bisphosphonates should be used in all patients with bone involvement that might create long-term articular (arthropathy) or neurologic (compression) complications. This aggressive strategy is the most likely to provide effective prevention of complications in the long term.

Discovery, clinical development, and therapeutic uses of bisphosphonates

OBJECTIVE

To review the literature concerning the history, development, and therapeutic uses of bisphosphonates.

DATA SOURCES

English-language articles were identified through a search of MEDLINE (through December 2004) using the key word bisphosphonate. Reference lists of pivotal studies, reviews, and full prescribing information for the approved agents were also examined.

STUDY SELECTION AND DATA EXTRACTION

Selected studies included those that discussed the discovery and initial applications of bisphosphonates, as well as their historical development, pharmacokinetic and pharmacodynamic properties, and current therapeutic uses.

DATA SYNTHESIS

Bisphosphonates structurally resemble pyrophosphates (naturally occurring polyphosphates) and have demonstrated similar physicochemical effects to pyrophosphates. In addition, bisphosphonates reduce bone turnover and resist hydrolysis when administered orally. The information gained from initial work with etidronate generated a considerable scientific effort to design new and more effective bisphosphonates. The PCP moiety in the general bisphosphonate structure is essential for binding to hydroxyapatite and allows for a number of chemical variations by changing the 2 lateral side chains (designated R(1) and R(2)). The R(1) side chain determines binding affinity to hydroxyapatite, and the R(2) side chain determines antiresorptive potency. Accordingly, each bisphosphonate has its own characteristic profile of activity.

CONCLUSIONS

The bisphosphonates reduce bone turnover, increase bone mass, and decrease fracture risk and therefore have a significant place in the management of skeletal disorders including osteoporosis, Paget's disease, bone metastases, osteogenesis imperfecta, and heterotopic ossification.

Olpadronate: a new amino-bisphosphonate for the treatment of medical osteopathies

Olpadronate is a nitrogenated bisphosphonate. Although it shares the therapeutic and pharmacological properties of pamidronate and alendronate, it has a greater dosage amplitude, more predictable effects and a greater digestive tolerability than other bisphosphates. Therefore, it may be more appropriate in the treatment of medical osteopathies, by both oral and parenteral routes of administration. According to various experimental and human models, the pharmacological potency of olpadronate is 5- to 10-times higher than that of pamidronate and close to that of alendronate. The two methyl groups bound to the nitrogen atom give the compound a high water solubility, which is about 8-times higher than that of the two other bisphosphonates. The lack of a terminal amino group in the side-chain of the molecule and the absence of crystallised forms of the compound in the digestive tract (due to its high water solubility) may avoid the potential for inducing oesophageal and gastrointestinal side-effects. These features may explain the high tolerability reported after the administration of doses of olpadronate (by the oral route) up to 5- to 10-times higher than the maximum tolerated dose of alendronate in Paget's bone disease and bone metastases, thus widening the possibilities for its clinical usage. In addition, initial pharmacokinetic studies suggest that olpadronate's oral bioavailability would fit into a confidence range of 2-4%, which contrasts with the erratic absorption shown by other highly potent bisphosphonates. The clinical efficacy demonstrated in preliminary studies in Paget's bone disease (including ultra-short treatments), and also in single-dose iv. therapy of hypercalcaemia of malignancies, renders olpadronate among the most promising bisphosphonate compounds, with potential use in the treatment of a variety of bone-involving diseases, such as osteoporosis, malignancies and rheumatoid arthritis.

A randomized clinical trial comparing oral alendronate and intravenous pamidronate for the treatment of Paget's disease of bone

Second and third generation bisphosphonates are the treatment of choice for Paget's disease of bone. These drugs are more effective than calcitonin and etidronate, but there have been no head to head, randomized controlled trials comparing potent bisphosphonates. We conducted a 2-year, randomized, open-label trial comparing oral alendronate and intravenous pamidronate in 72 subjects with Paget's disease. Randomization was stratified according to baseline plasma total alkaline phosphatase (ALP) and previous bisphosphonate treatment (yes or no). All previously treated patients had received pamidronate but not alendronate. Assigned treatments were pamidronate (60 mg) every 3 months as a single infusion or alendronate (40 mg) daily in 3-month blocks, continued until biochemical remission (defined as both ALP and urine deoxypyridinoline (DPD)/creatinine ratio in the reference range) or a clear plateau effect was observed. At 1 year, nonresponders to pamidronate were crossed over to alendronate treatment. At 1 year, 31/36 (86%) subjects randomized to alendronate achieved biochemical remission compared with 21/36 (56%) for pamidronate (P = 0.017). There was a significantly greater reduction in ALP (P < 0.001) and DPD/creatinine ratio (P < 0.001) for alendronate compared with pamidronate treatment. In previously untreated patients, alendronate resulted in remission in 20/22 (91%) subjects compared with 19/22 (86%) of pamidronate-treated subjects, which was not significantly different; however, alendronate resulted in a significantly greater reduction in ALP (P = 0.014) and DPD/creatinine ratio (P < 0.001). In previously treated patients, alendronate resulted in remission in 11/14 (79%) subjects compared with 2/14 (14%) for pamidronate (P < 0.001), with a significantly (P < 0.001) greater reduction in both ALP and DPD/creatinine ratio. Of subjects crossed over from pamidronate to alendronate, 10/14 (71%) achieved remission, including 9/11 (82%) previously treated patients. We conclude that, in patients with previously untreated Paget's disease of bone, alendronate and pamidronate have similar efficacy in achieving biochemical remission. In patients previously treated with pamidronate, alendronate is more effective.

Paget's disease of bone

Paget's disease of bone is characterized by an anarchic bone remodelling, associated with morphological and functional abnormalities of osteoclasts. Its prevalence and incidence rates decreased gradually over the past two decades; the reason for this remains unclear. The aetiology of the disease is still obscure, the paramyxoviral theory being very controversial. Recent advances in understanding of the disease come from genetic studies, with the identification of specific mutations in the p62-sequestosome gene, which could be involved in pathogenetic mechanisms leading to increased osteoclast activity. The disease affects one or several bone pieces, leading to bone pain, deformities, characteristic imaging features, and increased markers of bone remodelling. The long-lasting disease activity leads to complications, including arthropathies, neurological compressions, fissures or fractures and, rarely, osteosarcomatous transformation of a pagetic lesion. Potent bisphosphonates have proven their efficacy in reducing symptoms and disease activity. They are currently used as the first-line treatment with the goal of normalizing bone remodelling and, hopefully, preventing late complications.

Determinants of induction and duration of remission of Paget's disease of bone after bisphosphonate (olpadronate) therapy

Bisphosphonates are the treatment of choice of Paget's disease of bone. For optimal patient care determinants of the induction and duration of remission of the disease after bisphosphonate therapy must be defined. We addressed these issues in a longitudinal study of 157 patients with biochemically active disease (serum alkaline phosphatase activity >120 U/L) treated with the bisphosphonate olpadronate and followed for a median period of 37 months (range 3-162, mean 46 +/- 30). Two different total doses of olpadronate were used: an effective dose (40 mg intravenously given over 5 or 10 consecutive days) and a high dose consisting of the effective dose followed by oral olpadronate 200 mg/day for 15 days. Treatment induced biochemical remission, defined as normalization of serum alkaline phosphatase activity, in 89.2% of the patients. There were no differences between the two treatment regimens. The only independent determinants of induction of remission were baseline serum alkaline phosphatase activity and number of affected bones. In contrast, duration of remission depended on the dose of olpadronate given (high versus effective dose, RR of relapse 0.49, 95% CI 0.27-0.89). Additional independent determinants of relapse were nadir value of serum alkaline phosphatase activity after treatment, number of previous therapies, and number of affected bones. Pain scores decreased with therapy in 88% of patients with pain complaints. Pain scores were significantly related to the probability of relapse (RR1.54, 95% CI 1.04-2.27). In this long-term study of a large cohort of patients with Paget's disease we confirmed the efficacy of olpadronate therapy. In addition, we identified and quantified determinants of the response to bisphosphonate that can help in improving the management of patients with Paget's disease with bisphosphonates.

Fever After Zoledronic Acid Administration Is Due to Increase in TNF-αand IL-6

The most common adverse event typically associated with bisphosphonate therapy is transient fever. The aim of this study was to define the role of the main cytokines of the acute-phase reaction interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) involved in the pathogenesis of zoledronic acid-induced fever. Eighteen consecutive cancer patients with bone metastases were treated, for the first time, with a single dose of 4 mg zoledronic acid infusion. They were prospectively evaluated for circulating TNF-alpha, interferon-gamma (IFN-gamma), and IL-6 levels at different times, just before and 1, 2, 7, and 21 days after diphosphonate infusion. Clinical and standard laboratory parameters were recorded at the same time points. TNF-alpha circulating levels increased significantly 1 and 2 days after zoledronic acid infusion (respectively, p = 0.002 and p < 0.001) and then decreased to levels similar to the basal levels. IL-6 levels increased significantly 1 day after the infusion (p = 0.007), returning to values similar to the median basal values 2 days after zoledronic acid administration. Moreover, in patients who experienced fever, the TNF-alpha and IL-6 increases were higher than in patients without fever. No statistically significant differences in IFN-gamma were identified at different time points in patients with and without fever. Our results show that zoledronic acid induces transient TNF-alpha and IL-6 increases and that these increases are higher in patients who have developed fever, suggesting that these cytokines could be responsible for fever pathogenesis. The sharp reduction in serum calcium levels observed in patients with fever may be related to zoledronic acid pharmacokinetic modifications.

The antineoplastic role of bisphosphonates: from basic research to clinical evidence

Bisphosphonates are now well established as successful agents for the prevention and treatment of postmenopausal osteoporosis, corticosteroid-induced bone loss and Paget's disease. Bisphosphonates have also recently become important in the management of cancer-induced bone disease, and they now have a widely recognized role for patients with multiple myeloma and bone metastases secondary to breast cancer and prostate cancer. Recent studies suggest that, besides the strong antiosteoclastic activity, the efficacy of such compounds in the oncological setting could also be due also to direct antitumor effect, exerted at different levels. Here, after a brief analysis of the chemical structure, we will review the antineoplastic and biological properties of bisphosphonates. We will start from well estabilished mechanisms of action and go on to discuss the latest evidence and hypotheses. In particular, we will review the antiresorptive properties in malignant osteolysis and the recent evidence of a direct antitumor effect. Furthermore, this review will analyze the influence of bisphosphonates on cancer growth factor release, their effect on cancer cell adhesion, invasion and viability, the proapoptotic potential on cancer cells, the antiangiogenic effect, and, finally, the immunomodulating properties of bisphosphonates on the gammadelta T cell population.

Oral bisphosphonates and upper gastrointestinal tract problems: what is the evidence?

OBJECTIVE

To review and evaluate the evidence regarding possible associations of bisphosphonate use with upper gastrointestinal (GI) tract adverse events (AEs).

METHODS

We reviewed and summarized published information and abstracts regarding upper GI tract safety and tolerability of bisphosphonates, including laboratory and animal studies, epidemiological (observational) studies, endoscopy studies, and randomized controlled trials (RCTs). The evidence was summarized by using the principles of evidence-based medicine, giving the greatest credence to high-quality RCTs.

RESULTS

Clinical reports of esophagitis associated with bisphosphonate use appear to have declined in frequency once the importance of proper administration was explained to physicians after early reports of complications. Conflicting results have been reported in endoscopy studies; some reported no significant increase in upper GI tract lesions, whereas others reported a higher incidence of gastric (but not esophageal) lesions among patients taking oral bisphosphonates. Endoscopy studies that reported differences were of short duration (2 weeks) and were not of double-blind design. Results from large RCTs involving thousands of participants detected no increase in upper GI tract AEs among individuals treated with bisphosphonates. Other studies of patients who discontinued taking bisphosphonates and were randomized to blinded re-treatment with either a bisphosphonate or placebo show that most patients (>85%) were able to continue treatment, with no difference in AEs between the bisphosphonate and placebo groups.

CONCLUSIONS

The highest level of evidence, RCTs, suggests little or no increase in risk of upper GI tract problems if bisphosphonates are administered properly. Upper GI tract symptoms are common among patients with osteoporosis. The evidence suggests that many upper GI tract AEs reported during therapy with bisphosphonates may reflect a high background incidence of upper GI tract complaints and an increased sensitivity to detection rather than a causal relationship to therapy.

Bisphosphonates in bone diseases other than osteoporosis

The range of bone diseases in which bisphosphonates are used has extended far beyond osteoporosis during the last few years. Bisphosphonate therapy is now so well validated as to be the reference standard in Paget's disease and in the prevention of bone complications related to malignant osteolysis. Promising preliminary findings warrant the use of bisphosphonates in conditions that are either rare (fibrous dysplasia) or severe (pediatric osteogenesis imperfecta). The third category of indications encompasses many conditions in which the limited available data do not warrant widespread use: examples include reflex sympathetic dystrophy syndrome, acute back pain after a vertebral crush fracture, and chronic inflammatory joint disease not treated by glucocorticoids.

Modern Therapy for Paget??s Disease of Bone

There has been a dramatic change in the therapeutic approach to patients with Paget's disease of bone over the last 40 years. In the 1960s, only symptomatic therapy could be given, with control of pain the main objective. Analgesics and nonsteroidal anti-inflammatory drugs were the most commonly used agents. From 1968 onwards, antiosteoclastic agents became available, including calcitonin, plicamycin (mithramycin) and etidronate (etidronic acid), a first-generation bisphosphonate. Limitations with these agents, including potentially deleterious effects on bone mineralization with etidronate (etidronic acid), has cleared the way for increasingly potent second- and third-generation bisphosphonates, including clodronate (clodronic acid), pamidronate (pamidronic acid), alendronate (alendronic acid) and risedronate (risedronic acid). Even more potent bisphosphonates will become available in the near future. With the newer bisphosphonates, there is some hope for long-term remission (if not definitive healing) of pagetic lesions, as well as prevention of long-term complications in both symptomatic and asymptomatic patients. Thus, indications for therapy have been extended to include younger patients to prevent bone deformity of the limbs and skull, leading to secondary osteoarthritis, facial deformities and potentially to sarcoma transformation; as well as to elderly patients to prevent bone fragility, leading to fracture, and pagetic vascular steal syndromes. The increased potency and longer duration of action of newer bisphosphonates more than compensates for their marginally increased cost compared with older bisphosphonates.

Usefulness of biochemical markers of bone turnover in assessing response to the treatment of Paget's disease

The aim of this study was to investigate the usefulness of biochemical markers of bone turnover for monitoring treatment efficacy of Paget's disease of bone, and also to evaluate the utility of biological variation data in choosing the best markers for assessment of biochemical response to therapy. Thirty-eight patients with Paget's disease were included in a prospective study. All received 400 mg/day of oral tiludronate for 3 months. In 31 patients that completed treatment, biochemical markers were measured at baseline and at 1 and 6 months after treatment ended. In serum we determined the levels of total alkaline phosphatase (tAP), bone alkaline phosphatase (bAP), procollagen type I N-terminal propeptide (PINP), and C-terminal telopeptide of type I collagen (sCTx). Urine samples were analyzed for hydroxyproline (Hyp) and for C- and N-terminal telopeptides of type I collagen (CTx and NTx, respectively). Quantitative bone scintigraphy was performed at baseline and at 6 months after discontinuation of therapy. A ratio for monitoring response to treatment was obtained for each marker. This ratio reflected the size of treatment response of the marker in relation to the value of its critical difference. Thus, ratio values of >1 indicated a significant decrease of the marker after therapy. In addition, response to therapy was evaluated according to disease activity. Mean values of all markers of bone turnover decreased significantly after therapy. Serum bAP and PINP and urinary NTx showed the highest percentage reduction (between 58% and 68%). Furthermore, serum bAP and PINP showed the highest ratios for monitoring changes induced by treatment, followed by serum tAP and urinary NTx. sCTx and urinary CTx as well as Hyp showed mean ratios for monitoring changes of <1, indicating a low sensitivity for monitoring treatment. Patients with polyostotic disease showed a continuous decrease in mean values for all markers at 6 months from the end of therapy, whereas, in monostotic patients, there was a trend toward increased levels at this timepoint. In conclusion, serum bAP and PINP were the most sensitive markers for monitoring treatment efficacy in Paget's disease, although serum tAP and urinary NTx were also sensitive markers for monitoring changes. Data on biological variation are useful for assessing actual changes induced by treatment.

Consensus statement on the modern therapy of Paget's disease of bone from a Western Osteoporosis Alliance symposium. Biannual Foothills Meeting on Osteoporosis, Calgary, Alberta, Canada, September 9-10, 2000

BACKGROUND

Bisphosphonate therapy remains the most effective way of controlling Paget's disease of bone (PD). Along with salmon calcitonin, etidronate has been the mainstay of therapy for approximately 20 years. However, the advent of newer bisphosphonates with different molecular actions on osteoclasts warrants a reevaluation of optimal treatment.

OBJECTIVE

At a symposium of the Western Osteoporosis Alliance, physicians with experience in the management of PD met to review currently available information and generate this consensus statement as a guideline for clinicians and a source of information for health care payers.

METHODS

All available randomized, double-blind, controlled studies that compared the efficacy of newer bisphosphonates with that of etidronate in the treatment of PD were identified through a search of MEDLINE using the terms Paget's disease, bisphosphonates, pamidronate, etidronate, alendronate, risedronate, tiludronate, clodronate, calcitonin, and salmon calcitonin. Because no such studies have been conducted for pamidronate, clodronate, or calcitonin, these drugs were not included in the analysis.

CONCLUSIONS

The consensus of the symposium was that etidronate has little place in the modern management of PD. Newer bisphosphonates such as alendronate and risedronate provide significant therapeutic advantages over etidronate, both in the extent of reduction in bone-specific alkaline phosphatase (BSAP) and/or total serum alkaline phosphatase (SAP) and in the duration of remission, as measured by normalization of BSAP/SAP. In the absence of a direct comparison between alendronate and risedronate in the treatment of PD, physician choice is likely to be based on personal experience, relative cost, and differences in dosing.

Osteoporosis therapies for rheumatoid arthritis patients: minimizing gastrointestinal side effects

OBJECTIVE

This manuscript identifies characteristics that put people with rheumatoid arthritis (RA) at high risk for osteoporosis or gastrointestinal (GI) disturbances. The manuscript then reviews therapies available for osteoporosis in the United States and makes recommendations about choosing therapies that minimize GI adverse effects in RA patients at high risk for such events.

DATA SOURCES

References identified through MEDLINE, abstracts, and prescribing information for individual drugs.

DATA EXTRACTION

Characteristics that predispose patients to osteoporosis and GI problems were identified. Data on individual osteoporosis therapies were assessed by risk-benefit analysis and appropriateness for use in patients at risk for GI disturbances.

DATA SYNTHESIS

High risk of osteoporosis in people with RA is caused by disease activity, medication effects, physical inactivity, and standard risk factors such as postmenopausal status and increased age. Patients with RA are frequently at high GI risk if they are receiving nonsteroidal anti-inflammatory drugs or corticosteroids. Because of the high potential for erosive esophagitis and other upper GI disorders with alendronate, caution is warranted in prescribing alendronate to RA patients with high GI risk. In such patients, estrogen replacement therapy, selective estrogen receptor modulators, or calcitonin should be considered for treatment, and either estrogen replacement therapy or selective estrogen receptor modulators should be considered for osteoporosis prevention.

CONCLUSIONS

Assessment of GI risk is important in patients with RA and osteoporosis. Risk factors should be considered when choosing osteoporosis therapies.