Response to Zoledronic Acid in Patients with Active Paget's Disease of Bone: A Retrospective Study

Bone scan findings of Paget's disease of bone in patients with VCP Multisystem Proteinopathy 1

Multisystem Proteinopathy 1 (MSP1) disease is a rare genetic disorder caused by mutations in the Valosin-Containing Protein (VCP) gene with clinical features of inclusion body myopathy (IBM), frontotemporal dementia (FTD), and Paget's disease of bone (PDB). We performed bone scan imaging in twelve patients (6 females, 6 males) with confirmed VCP gene mutation six (50%) of which has myopathy alone, four (33%) with both PDB and myopathy, and two (15%) were presymptomatic carriers. We aim to characterize the PDB in diagnosed individuals, and potentially identify PDB in the myopathy and presymptomatic groups. Interestingly, two patients with previously undiagnosed PDB had positive diagnostic findings on the bone scan and subsequent radiograph imaging. Among the individuals with PDB, increased radiotracer uptake of the affected bones were of typical distribution as seen in conventional PDB and those reported in other MSP1 cohorts which are the thoracic spine and ribs (75%), pelvis (75%), shoulder (75%) and calvarium (15%). Overall, we show that technetium-99m bone scans done at regular intervals are a sensitive screening tool in patients with MSP1 associated VCP variants at risk for PDB. However, diagnostic confirmation should be coupled with clinical history, biochemical analysis, and skeletal radiographs to facilitate early treatment and prevention complications, acknowledging its limited specificity.

A rare case of asymptomatic Paget's disease of the skull in a 60-year-old Asian female

Background and Aim

Paget's disease of the bone refers to a chronic cumulative disorder characterized by enhanced osteoclastic function followed by a secondary surge in osteoblastic activity. The condition can manifest as a polyostotic or monostotic bone disease with most patients having an asymptomatic presentation, although some may complain of pain localized to the affected bone while others express symptoms of nerve compression. A pagetic bone is predisposed to develop pathological fractures, bony deformities, and a rare yet detrimental transformation into osteosarcoma. Detection is often accidental when performing radiographic tests for other indications or when elevated blood levels of alkaline phosphatase (ALP) are detected. Treatment with third-generation bisphosphonates is helpful in preventing further bone resorption and, additionally, reduces bony pains that are believed to be caused by excessive metabolic activity. Here, we present a case of a middle-aged asymptomatic female with elevated serum ALP levels up to 1537 IU/L (reference range 40-150 U/L) during her pre-operative evaluation for elective cholecystectomy.99m Tc-methylene diphosphonate bone scintigraphy revealed diffuse uptake in the skull and, hence, was diagnosed as a case of isolated Paget's disease of the skull.

Relevance for Patients

The rarity of this disease in Southeast-Asians, its uncontrived detection, and the isolated skull involvement, imparts high clinical relevance on this case. Early detection and management of this disease can help prevent the development of life-threatening complications in affected patients, hence decreasing the morbidity.

The Superiority of Zoledronic Acid Over Risedronate for Paget's Disease: A 16-Year Experience at a Single Institution

Introduction Bisphosphonates are considered to be the treatment of choice for patients with active Paget's disease. The aim of this study was to record and assess the therapeutic effect in response to a single intravenous infusion of 5mg zoledronic acid or oral risedronate. Methods A retrospective observational study was conducted of 89 patients in Greek patients with active Paget's disease from a tertiary hospital in North Greece. Patients were treated with either a single intravenous infusion of 5mg zoledronic acid (1st group, n=46) or 30mg of risedronate per day for 60 days (2nd group, n=43). All patients received 1000mg of calcium and 400-800IU of calciferol daily. The primary outcome measure was to record the therapeutic response defined as the control of patients' symptoms and normalization of the biochemical markers of bone metabolism. The secondary outcome measures included the patient's quality of life which was evaluated by the questionnaire SF-36 and adverse events. Results Forty patients from the zoledronic acid group and 38 patients from the risedronate group, who reported pain at the beginning of the study, showed a significant degree of clinical improvement. All the patients in our study showed a therapeutic response at six months while the remission was persistent at 36 months. There was a statistically significant difference between pre-treatment basal results and values at the sixth and 36th months of treatment (p<0.001) between the two groups. Conclusion The study demonstrated the superiority of zoledronic acid over risedronate in patients with active Paget's disease.

Zoledronate

Zoledronate is the most potent and most long-acting bisphosphonate in clinical use, and is administered as an intravenous infusion. Its major uses are in osteoporosis, Paget's disease, and in myeloma and cancers to reduce adverse skeletal related events (SREs). In benign disease, it is a first- or second-line treatment for osteoporosis, achieving anti-fracture efficacy comparable to that of the RANKL blocker, denosumab, over 3 years, and it reduces fracture risk in osteopenic older women. It is the preferred treatment for Paget's disease, achieving higher rates of remissions which are much more prolonged than with any other agent. Some trials have suggested that it reduces mortality, cardiovascular disease and cancer, but these findings are not consistent across all studies. It is nephrotoxic, so should not be given to those with significant renal impairment, and, like other potent anti-resorptive agents, can cause hypocalcemia in patients with severe vitamin D deficiency, which should be corrected before administration. Its most common adverse effect is the acute phase response, seen in 30-40% of patients after their first dose, and much less commonly subsequently. Clinical trials in osteoporosis have not demonstrated increases in osteonecrosis of the jaw or in atypical femoral fractures. Observational databases are currently inadequate to determine whether these problems are increased in zoledronate users. Now available as a generic, zoledronate is a cost-effective agent for fracture prevention and for management of Paget's disease, but wider provision of infusion facilities is important to increase patient access. There is a need to further explore its potential for reducing cancer, cardiovascular disease and mortality, since these effects could be substantially more important than its skeletal actions.

Is Paget Disease of Bone more Common in South India? Clinical Characteristics, Therapeutic Outcome and follow-up of 66 Patients from Tamil Nadu

INTRODUCTION

Paget disease of bone (PDB) is a disorder of altered bone remodeling mainly characterized by increased osteoclastic activity. While the exact Indian prevalence remains unknown, a clustering of published cases suggests South Indian predominance.

OBJECTIVE

To study the clinico-biochemical profile and therapeutic response of patients with PDB and briefly review the epidemiology of PDB from an Indian perspective.

MATERIALS AND METHODS

Retrospective data was collected from the charts of patients who have been seen in endocrine out-patient clinics in Tamil Nadu over a 12-year period. Published literature on PDB from India was reviewed.

RESULTS

A total of 66 patients (71% males) predominantly from Tamil Nadu were studied. The mean age at presentation was 67 ± 8 years. Polyostotic involvement was seen in 89% and familial occurrence of PDB in 5 patients. Symptoms at presentation mainly included bone pain (51%) and skeletal deformities (18%). Scalp vein sign (21%) and sensorineural hearing loss (64%) were also noted. Incidental PDB detection by raised serum alkaline phosphatase (SAP) levels was observed in 17% and by abnormal fluorodeoxyglucose-positron emission tomography (FDG-PET) scan in 6% of cases. Mean SAP at presentation was 606 ± 438 IU/L (Normal, 76-140). Major skeletal site involvement includes pelvis (62.1%) and spine (34.8%). Mean (range) follow-up of the cohort was 3.4 yrs (1-12 yrs). In all, 64 subjects received zoledronate and two received alendronate, and mean (SD) SAP at 1-year was 73 ± 42 IU/L. All but two showed remission at the end of 1 year. Two had pathological fractures and two had sarcomas. A review of epidemiology of PDB in Indian literature clearly showed a South Indian predilection for unclear reasons.

CONCLUSION

In our cohort of PDB, male gender, polyostotic involvement, and hearing impairment were noted in more than two-thirds of patients and single-dose intravenous zoledronate was effective in normalizing SAP in almost all patients. PDB is intriguingly more common in South India and this needs more exploration.

Management of Paget's disease of bone

Paget's disease is a progressive focal bone condition which can result in pain, low quality of life, deformity and other complications. Disease progression can be halted with potent bisphosphonates, resulting in improvement in both quality of life and pain, and normalisation of scintigraphy, plain radiographs and bone histology. Zoledronate has transformed the treatment of Paget's disease, producing sustained remissions in almost all patients. Thus, it is now possible to normalise bone cell activity and prevent disease progression at low cost, with one or two intravenous injections of zoledronate, greatly reducing follow-up costs. Patients with Paget's disease who are symptomatic or at risk of complications should have the opportunity to reap these therapeutic benefits. Potent bisphosphonates are highly effective in halting disease progression in Paget's disease, but guidelines disagree about treatment indications. The efficacy, safety and low cost of zoledronate recommend its use in any patient who is symptomatic or judged to be at risk of complications from Paget's disease.