ZOLEDRONIC ACID THERAPY OF PATIENTS WITH PAGET DISEASE OF BONE RESISTANT TO OR WITH UNSUSTAINED REMISSION FOLLOWING PRIOR BISPHOSPHONATE THERAPY

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.

Long-Term Efficacy of Intensive Zoledronate Therapy and Predictors of Retreatment in Paget's Disease of Bone

Despite the current debate on the best therapeutic approach, i.e. symptomatic vs intensive strategy, one zoledronate (Zol) infusion is effective in most patients with Paget's disease of bone (PDB), whereas few need retreatment, whose predictors are not well established. We aimed to evaluate long-term efficacy of intensive Zol therapy and predictors of retreatment in PDB. Pagetic complications, clinical and biochemical response to Zol together with frequency of retreatment were retrospectively assessed in forty-seven PDB patients (age, mean ± SD: 72.5 ± 8.9 years, M/F: 24/23; symptomatic/asymptomatic: 16/31). Statistical analysis for retreatment prediction were based on Mann-Whitney U test, Pearson's Χ2 and ROC curve analysis. During seven-year follow-up, all patients achieved pain relief and only one underwent arthroplasty. Bone alkaline phosphatase (BAP) detected three non-responder (6%) and six relapsing (13%) patients needing retreatment. Retreated patients had less old age (66.1 ± 11.2 vs 74.0 ± 7.7 years), higher frequency of polyostotic disease (78% vs 40%) and higher baseline (96.5 ± 24.8 vs 44.9 ± 27.7 mcg/l) and post-Zol nadir BAP levels (24.7 ± 24.1 vs 8.1 ± 4.1 mcg/l) than patients treated once (p < 0.05 for all comparisons). In multivariate analysis both serum baseline and post-Zol nadir BAP significantly predicted retreatment (OR 1.09, 95%CI 1.01-1.17 and 1.29, 1.03-1.62, respectively), with ROC curve analysis showing the greatest accuracies for threshold values of 75.6 and 9.9 mcg/l (sensitivity 88 and 90%, specificity 94 and 86%, AUC 0.92 and 0.93, respectively). Our data in mostly asymptomatic, metabolically active PDB patients treated with intensive Zol therapy show a negligible incidence of pagetic complications and long-term optimal disease control, with BAP being the best predictor of retreatment.

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

BACKGROUND

Traditionally, bisphosphonates are used to treat active Paget's disease of bone (PDB). Intravenous zoledronic acid (ZA) is the most effective treatment option leading to sustained remission.

OBJECTIVE

The primary objective of this study was to analyze the effect of intravenous ZA in patients with active PDB in a tertiary care center of India.

MATERIALS AND METHODS

Retrospective data of 13 patients with active PDB who received a single dose of 4 mg intravenous ZA at our institute from January 2011 to June 2017 were reviewed. Response to therapy was monitored clinically, biochemically by serum alkaline phosphatase (ALP), and scintigraphically by 99m-Technetium methylene diphosphonate bone scan.

RESULTS

All of our patients reported relief of bone pain. The mean duration of follow-up in our study was 35.2 ± 16.8 months. Serum ALP levels reduced significantly from 1190.9 ± 666.1 IU/L (n = 13) at baseline to 200.5 ± 68.4 IU/L (n = 13) at 6 months (P < 0.001). ALP level at 1 year was 174 ± 33.6 IU/L (n = 12), which remained stable till 36 months at 176.5 ± 50 IU/L (n = 8). This indicates that remission achieved by 6 months post ZA is sustained for at least 3 years. Scintigraphic ratio reduced from 9.6 [interquartile range (IQR) 5.25-18.2] at baseline to 2.7 (IQR 1.20-4.05) at follow-up (P < 0.001). Similarly, scintigraphic index of involvement reduced from 9.9 (IQR 5.6-28.5) at baseline to 3 (IQR 2-4) at follow-up (P = 0.018).

CONCLUSION

A 4 mg single dose of intravenous ZA results in clinical, biochemical, and scintigraphic response that is sustained for at least 3 years.

Long-Term Bone Scintigraphy Results After Intravenous Zoledronate in Paget's Disease of Bone

Zoledronate produces long-term normalization of biochemical markers in Paget's disease but whether this implies the absence of active disease is unknown. We have determined whether bone scintigraphy, a more sensitive index of disease activity, is also normalized ≥5 years after treatment with zoledronate. A consecutive case series of 11 individuals with Paget's disease treated with zoledronate 5 mg ≥5 years previously is reported. Eight patients received a single zoledronate infusion and were assessed 55-120 months later. Bone scintigraphy showed no evidence of active disease in four of these patients, and there was minimal residual disease activity in the other four. Three other patients required second infusions because of evidence of ongoing disease activity. In two of these, scintigraphy was normal ~90 months after their second infusions. In the third, further follow-up is not available. Procollagen-I N-terminal propeptide and total alkaline phosphatase were normal in all subjects at the time of bone scintigraphy. This case series confirms the high rate of response of Paget's disease to zoledronate, demonstrates the much greater sensitivity of scintigraphy compared with biochemical markers in detecting ongoing disease activity, and indicates that about one-third may be scintigraphically "cured" after one infusion; one-third have scintigraphically trivial disease activity subsequently, and the balance may require a second infusion. Scintigraphic "cure" is achievable after second infusions. Scintigraphy has an important place in the long-term management of Paget's patients following zoledronate, and should guide follow-up decisions in those with normal biochemical markers.

Asymptomatic Paget's disease of bone in a 62-year-old Nigerian man: three years post-alendronate therapy

Paget's disease is a chronic and progressive disorder of bone characterized by focal areas of excessive osteoclastic resorption accompanied by a secondary increase in the osteoblastic activity. Paget's disease of bone (PBD) is a rare endocrine disease especially among Africans and Asians. Hence the detection of a case in a middle-aged Nigerian is of interest. We present the case of a 62-year-old Nigerian man in apparent good health who was found to have a markedly elevated serum total alkaline phosphatase (ALP) of 1179 U/l (reference range, 40–115 U/l) 4 years ago during a routine medical check-up in the USA. He had no history suggestive of PDB and also had no known family history of bone disease. Examination findings were not remarkable except for a relatively large head. A repeat ALP in our centre was 902 U/l (reference range, 40–120 U/l). Cranial CT scan showed diffuse cranial vault thickening consistent with Paget's disease which was confirmed by Tc-99m hydroxymethylene diphosphonate. He was placed on 40 mg alendronate tablets daily for 6 months. The patient has remained asymptomatic and has been in continuing biochemical remission during the 3-year follow-up period. The most recent ALP result is 88 U/l (reference range, 30–132 U/l) in April 2015.