[Effect of pamidronate on clinical symptoms and bone metabolism in fibrous dysplasia and McCune-Albright syndrome]

Efficacy of antiresorptive agents in fibrous dysplasia and McCune Albright syndrome, a systematic review and meta-analysis

Fibrous dysplasia (FD) is a rare skeletal disorder in which normal bone is replaced by a fibro-osseous tissue, resulting in possible deformities and fractures. The aim of this systematic review and meta-analysis was to synthesize the available evidence on the use of antiresorptive drugs in FD in terms of changes in bone turnover markers (BTMs), bone mineral density (BMD), and reducing pain. Three databases were searched in October 2022, with an update in July 2023. Of the 1037 studies identified, 21 were retained after eligibility assessment. A random-effects model was used to calculate global effect size and the corresponding standard error. Pamidronate and Denosumab were the most reported drugs in a total of 374 patients assessed. The initiation of treatments was accompanied by an average reduction of 40.5% [CI95% -51.6, -29.3] in the bone resorption parameters, and 22.0% [CI95% -31.9, -12.1] in the parameters of bone formation after 6-12 months. BMD was increased in both FD lesions and in the unaffected skeleton. Pain was reduced by 32.7% [CI95% -52.7, -12.6] after 6-12 months of treatment, and by 44.5% [CI95% -65.3, -23.6] after a mean 41.2 months of follow-up. The variation in pain was highly correlated to variation in bone resorption (R2 = 0.08, p < 0.0001) and formation parameters (R2 = 0.17, p < 0.0001). This study supports the overall efficacy of antiresorptive therapies in terms of reducing bone remodeling, improving bone density, and pain in FD.

Medication Correction of the Bone Tissue’s Structural Condition in Patients with Different Forms of Braitsev-Lichtenstein Disease

The article presents a modern view on anti-osteoporotic medication therapy in patients with various forms of Braitsev-Lichtenstein disease. Against the background of fundamental studies of the bone tissue’s structural condition in this pathology improved and tested medication correction of its disorders depending on changes in bone metabolism, shape, clinical and orthopedic manifestations of the disease, the patient’s age. The article presents the rationale, general principles and features of anti-osteoporotic therapy; indications and contraindications to it; dose calculations and regimens for the use of certain medications, including from the group of bisphosphonates in various forms of Braitsev-Lichtenstein disease. The presented medication therapy has been successfully tested in 16 patients with Braitsev-Lichtenstein disease. The effectiveness of the treatment is confirmed by the reduction or elimination of pain, stopping the progression of pathological diseases on average in the bones of the lower extremities, improving the structural condition of bone tissue and its metabolism.

Outcome of Long-Term Bisphosphonate Therapy in McCune-Albright Syndrome and Polyostotic Fibrous Dysplasia

McCune-Albright syndrome (MAS) is a rare bone disorder characterized by fibrous dysplasia (FD), endocrinopathies, and café-au-lait patches. FD patients have been shown to respond favorably to treatment with bisphosphonates, but data are scarce in the more severe polyostotic form (PFD), including MAS, and factors determining treatment outcome are not known, particularly in the long-term. We evaluated the biochemical (bone turnover markers [BTMs]) and clinical (pain reduction) outcome of bisphosphonate therapy in 11 patients with MAS and 30 patients with PFD: median duration of treatment 6 years (range, 2 to 25 years). Prognostic factors for treatment outcome were identified in both groups. Patients with MAS were younger at diagnosis (p = 0.001), all had precocious puberty, and four (36%) had additional growth hormone (GH) excess associated with severe craniofacial FD. Extent of skeletal disease was more severe in MAS compared to PFD. MAS patients had higher serum alkaline phosphatase (ALP) concentrations (p = 0.005), higher skeletal burden scores (p < 0.001), and more fractures (p = 0.021). MAS patients had also higher levels of FGF-23 (p = 0.008) and higher prevalence of hypophosphatemia (p = 0.013). Twenty-four of 30 PFD patients (80%) demonstrated a complete clinical and biochemical response within a year of starting treatment (p = 0.015), compared to only four of 11 MAS patients (36%). There were no nonresponders. In the whole group, FGF-23, total ALP, P1NP, and CTX positively correlated with skeletal burden scores (all p ≤ 0.001), which was the only significant risk factor for an incomplete response to bisphosphonate therapy (p < 0.01). Our data suggest a beneficial and safe outcome of long-term bisphosphonate therapy in the majority of patients with PFD, although response to therapy was limited by the higher skeletal disease burden in MAS patients. In the PFD/MAS population studied, the only identified prognostic factor that influenced the outcome of bisphosphonate therapy was a high skeletal burden score. © 2016 American Society for Bone and Mineral Research.

Long-term pamidronate treatment of polyostotic fibrous dysplasia of bone: A case series in young adults

BACKGROUND

Limited information is available about long-term pamidronate treatment in adults with fibrous dysplasia (FD) of bone.

OBJECTIVE

The aim of this case series was to report the clinical outcomes and the biochemical and densitometric findings in a group of young adult patients with polyostotic FD treated for ≥3 years with IV pamidronate.

METHODS

Pamidronate was administered every 6 months (60 mg/d for 3 days) for 2 years. Thereafter, treatment was individualized. Pamidronate was administered at shorter or longer intervals based on response. Bone pain, radiography, serum bone alkaline phosphatase (BALP) activity, and urinary C-terminal cross-linking telopep-tide of type I collagen (CTX-I) concentration were assessed for a mean of 7 years. Bone mineral density (BMD) of FD areas (FDas) and contralateral areas (CLas) were measured at baseline and at 12 and 24 months. Data were collected prospectively.

RESULTS

Seven patients (5 women, 2 men; mean [SD] age, 31.0 [7.2] years [range, 22-43 years]) were included in the study. Patients received IV pamidronate for a mean of 6.9 years (median, 7.1 years [range, 3.7-10.9 years]). Pamidronate was associated with a reduction in bone pain and a significant reduction in BALP in all patients at the end of follow-up (P < 0.02). The mean reduction from baseline in CTX-I concentration (measured in 3 patients) was 56%; this difference was not significant. Mean BMD values of FDas were significantly increased at 12 months (by 5.9%; P < 0.05) compared with baseline; but was not significantly increased at 24 months (7.3%), probably reflecting a higher dispersion of values due to individual responses to treatment. No significant changes were observed in CLa BMDs. Mean BMD of FDa had a numerically lower decrease of 15.3% compared with CLa at baseline; these decreases with pamidronate were 10.8% at 12 months (P = NS) and 9.3% at 24 months (P < 0.05). Refilling of osteolytic lesions was not observed.

CONCLUSIONS

These patients with FD of bone treated with IV pamidronate long term had improvement in bone pain and BMD. The effectiveness of individualized pamidronate administration in the long-term treatment of FD in adult patients should be investigated in blinded controlled trials.

Intramedullary rod fixation of fibrous dysplasia without use of bisphosphonates

PURPOSE

Controversy exists regarding approach to treatment of pediatric patients with fibrous dysplasia.

METHODS

We retrospectively reviewed medical records of seven patients who were treated at our institution for fibrous dysplasia by intramedullary rod fixation without bisphosphonate supplementation.

RESULTS

Seven patients with a total of ten fibrous dysplasia lesion sites surgically treated by intramedullary rod fixation were included. Of these ten lesion sites, eight demonstrated pathologic fracture at the time of fixation. Complete fracture healing was observed in all eight sites, with no incidence of recurrent pathologic fractures examined radiographically. There were no major infections or neurologic deficits, and lesions appeared to stabilize.

CONCLUSIONS

In this series, intramedullary rod fixation proved to be successful in treatment of acute pathologic fracture and incompletely healed fibrous dysplasia lesions. We observed partial resolution of fibrous dysplasia lesions at all ten sites without significant long-term complications. Following treatment, there were no refractures.

LEVEL OF EVIDENCE

Level IV, case series.

Current approach to fibrous dysplasia of bone and McCune-Albright syndrome

Fibrous dysplasia (FD) of bone is an uncommon disease caused by sporadic, congenital mutations in the cAMP regulating protein, G(s)alpha. It is an example of somatic mosaicism in which a wide spectrum of disease is possible. Widespread skeletal involvement is often associated with varying combinations of café-au-lait skin spots, and/or endocrine dysfunction (precocious puberty, renal phosphate wasting, hyperthyroidism, and/or growth hormone excess). Unrecognized and untreated endocrine dysfunction can exacerbate the skeletal disease. The diagnosis is usually established on clinical grounds on the basis of physical examination and typical radiographic appearance. Occasionally, gene testing of affected tissue may be helpful. The skeletal sites involved with disease are established at an early age, and the complications of fracture deformity are most pronounced in childhood. Bone pain in the absence of a fracture is more common in adults, but can also be present in children. Treatment with bisphosphonates is usually effective at relieving pain, but probably has no effect on the natural history of the disease. Scoliosis, which was previously thought to be an uncommon occurrence, has been shown to be common and progressive, and as such, warrants investigation and, when necessary, surgical treatment. The surgical management of FD remains challenging. Timing and technique remain controversial, but some consensus exists in that grafting materials (of any type) usually fail and should not be a central aspect of the surgical approach. Intramedullary devices are in general superior to side plates and screws. In extremely widespread disease with very early fracture and deformity, no surgical approach will affect final functional outcome. Efforts should be made for the initiation of international collaborative studies to better define optimal surgical approaches to the treatment of this challenging disease.

Pamidronate treatment of polyostotic fibrous dysplasia: failure to prevent expansion of dysplastic lesions during childhood

AIMS

To examine outcomes of pamidronate treatment on fibrous dysplasia of bone in three children with McCune-Albright syndrome (MAS).

METHODS

Radiological evidence of fibrous dysplasia progress was reviewed for three children with MAS who were treated with pamidronate from age 2.5-5 years, for 8-10.5 years.

RESULTS

Despite minimal pain and a low fracture rate in long bones, except where gross deformity exists, all dysplastic lesions present in long bones continued to undergo uncontrolled expansion. In contrast, there were no major new changes in facial configuration, no clinically obvious expansion of sphenoid wing lesions and no encroachment on optic foramina or visual field restriction in any patient.

CONCLUSIONS

Despite previous reports of limitation or reduction in size of fibrous dysplasia lesions in adults and children, it is our experience that bisphosphonate treatment of polyostotic fibrous dysplasia in children with MAS does not arrest the expanding nature of these lesions.

Fibrous dysplasia

Fibrous dysplasia is a developmental disorder of bone that can present in a monostotic or polyostotic form. Primarily affecting adolescents and young adults, it accounts for 7% of benign bone tumors. Many of the asymptomatic lesions are found incidentally; the remainder present with symptoms of swelling, deformity, or pain. Fibrous dysplasia has been associated with multiple endocrine and nonendocrine disorders and with McCune-Albright and Mazabraud's syndromes. The etiology remains unclear, but molecular biology suggests a mutation in the G(s)alpha subunit and activation of c-fos and other proto-oncogenes. Fibrous dysplasia has a characteristic radiographic appearance. Most cases do not require intervention, but those that do usually are managed surgically with curettage, bone grafting, and, in some cases, internal fixation. When some intervention is necessary but surgery is not practical, treatment is with bisphosphonates. The prognosis generally is good, although poor outcomes are more frequent in younger patients and in those with polyostotic forms of the disease. The risk of malignant transformation is low.

Effect of pamidronate treatment in children with polyostotic fibrous dysplasia of bone

Intravenous infusions with the bisphosphonate compound pamidronate decrease bone pain and reportedly can lead to refilling of dysplastic lesions in adults with fibrous dysplasia (FD) of bone. Here we describe the effects of this treatment approach in 18 children and adolescents (age at start of therapy, 6.2-17.5 yr; eight girls) with polyostotic FD, who received pamidronate for 1.2-9.1 yr (median, 3.8 yr). Treatment cycles with pamidronate (1-1.5 mg/kg.d on 3 consecutive days) were given every 4 months. Levels of serum alkaline phosphatase and urinary collagen type I N-telopeptide were elevated at baseline and decreased continuously during the first 3 yr of therapy. There was no radiographic evidence of filling of lytic lesions or thickening of the bone cortex surrounding the lesions in any patient. Histomorphometric results in dysplastic bone tissue of patients receiving pamidronate (n = 7; time of therapy, 1.4-4.8 yr) were similar to those of patients without medical therapy (n = 9). No serious side effects were noted. In conclusion, pamidronate therapy appears to be safe in children and adolescents with polyostotic FD. However, we found no clear evidence that pamidronate has an effect on dysplastic lesions in such patients.

Effect of intravenous pamidronate on bone markers and local bone mineral density in fibrous dysplasia

Bisphosphonates have proven to be effective in patients with fibrous dysplasia of the bone (FD) as shown by their effect on bone pain, markers of bone turnover, or radiological changes. The aim of this study was to evaluate the usefulness of measuring bone mineral density (BMD) of affected bones to assess the efficacy of bisphosphonate treatment. Seven patients (mean age 26 years) received courses of 180 mg intravenous infusion of pamidronate every 6 months (60 mg/day during 3 days). Clinical symptoms, serum alkaline phosphatase, and urinary C-terminal cross-linking telopeptide of type I collagen were assessed every 3 months. BMD of total skeleton and X-rays of FD areas (FDa) were performed at baseline and at 12 months. BMD of FDa was compared with the contralateral side (CL) using the region of interest program on the total skeleton scan. BMD of total skeleton was normal at baseline. Average BMD of FDa was -11.4% compared with CL, a significantly greater difference than that observed between the left and right sides in healthy controls, -0.7% (P < 0.02). At 12 months bone pain diminished in all patients. Bone turnover markers decreased. Mean total skeleton BMD increased 3.3% (P < 0.02). Subregions of the total skeleton scan presenting FD lesions augmented: arms +9.6% (P < 0.02), legs +4.2%, and pelvis +3.5% (P < 0.05). The increase in mean BMD of FDa was +6.8% compared with +2.6% in CL. No changes were observed on the X-ray. These results indicate that simultaneous determination of markers of bone turnover and BMD of FDa is useful in short-term follow-up to determine the efficacy of intravenous pamidronate.

Intramedullary rodding and bisphosphonate treatment of polyostotic fibrous dysplasia associated with the McCune-Albright syndrome

The authors report the results of the management of five consecutive children with McCune-Albright syndrome. These children were treated with a combination of drug treatment (bisphosphonates) and surgical treatment with elongating intramedullary rods (Sheffield) for management of femoral and tibial lesions. This treatment was successful in all patients, as judged by improvement in their quality of life and in clinical parameters, such as decreased bone pain and fracture rate, and improved walking ability. Two of the five children had been wheelchair-bound before treatment. All children are now community ambulators. In 5 of 10 hips, there was a significant decrease in the neck-shaft angle over time compared with the immediate postoperative angle.

Clinical, endocrinological and radiography features in a child with McCune-Albright syndrome and pituitary adenoma

McCune-Albright syndrome is a rare syndrome presenting with polyostotic dysplasia, cafe-au-lait spots and multiple endocrinopathies that is very often combined with precocious puberty. We examined the clinical, endocrinological and radiological features in a boy with McCune-Albright syndrome and pituitary adenoma. X-rays, magnetic resonance (MRI) scan, whole body scintigraphy, single photon emission computer tomography (SPECT) and 3D-reconstruction from bone SPECT was performed to evaluate clinical improvement after treatment with sandostatin and pamidronic acid. After a six-month period of treatment with sandostatin and pamidronate, bone scintigraphy revealed significantly reduced activity. Treatment with bromocriptine and methimazole led to normalization of prolactin and thyroid hormone levels. Mobility of the patient improved. A significant improvement as a result of treatment with sandostatin and pamidronic acid was found in this patient with generalized fibrous dysplasia. So far, this condition has been treated with pamidronate only in adults, but severely affected children also benefit from this treatment regimen.

Bisphosphonate therapy in fibrous dysplasia

Fibrous dysplasia is proliferation of fibrous tissue within the bone marrow causing osteolytic lesions and pathologic fractures. Recently, second generation bisphosphonates have shown promise in the treatment of patients with fibrous dysplasia. In the current study, six patients with fibrous dysplasia were treated with either oral alone or oral and intravenous bisphosphonates. The participants were observed for changes in N-telopeptide, pain score, and radiographic changes. In the current study, the combination bisphosphonate therapy diminished pain, prevented fractures, lowered N-telopeptide values, and led to partial resolution of fibrous dysplasia lesions.

Bone mineral density response to long-term bisphosphonate therapy in fibrous dysplasia

Fibrous dysplasia of bone is a rare disease related to a genetic mutation in which bone formation at osseous sites is altered. In the last few years, bisphosphonates have become one of the choice drugs to treat this disease. A 26-yr-old woman presented after 6 wk of spontaneous right leg pain owing to a fissure fracture of the right femoral neck. She reported precocious puberty at the age of 2, with diagnosis of McCune-Albright syndrome. Radioisotope bone scanning, radiographic, biochemical, and densitometric studies were performed. Treatment with bisphosphonates was started because bone turnover biochemical markers were abnormal. Oral olpadronate followed by iv pamidronate substantially decreased bone resorption. Bone mineral density (BMD) of total skeleton and subareas was assessed by dual X-ray absorptiometry (DXA) throughout the 5 yr of treatment. At the end of this period, BMD of the total skeleton had increased 6.2%. However, BMD of the areas most affected by fibrous dysplasia, the legs and pelvis, had increased 12.7 and 11%, respectively. Region of interest analysis of individual bones of the legs performed with the total skeleton scan revealed that BMD of the areas most affected by fibrous dysplasia was lower than that of the less affected contralateral bones. During the first 3 yr, treatment with bisphosphonates substantially increased BMD of the right femur and tibia (22 and 28%, respectively). After that, values seemed to stabilize. DXA evaluation of the total skeleton and its subareas was useful to evaluate the efficacy of bisphosphonate treatment. Moreover, the plateau observed in BMD values after 3 yr of treatment suggests that treatment could have been discontinued when the densitometric values stabilized.

Intravenous pamidronate treatment of polyostotic fibrous dysplasia associated with the McCune Albright syndrome

OBJECTIVES

An open trial of pamidronate treatment was undertaken in 5 children and 4 young adults with polyostotic fibrous dysplasia associated with McCune Albright syndrome to assess clinical response, bone turnover, and cardiovascular status over a 2-year period.

STUDY DESIGN

Pamidronate was administered by intravenous infusion 1 mg/kg/d for 3 days every 6 months for 2 years. Bone turnover was measured at 0, 6, 12, 18, and 24 months with bone mineral density, and cardiac output was assessed by echocardiography at 0, 12, and 24 months.

RESULTS

All subjects reported marked reduction in bone pain and sustained increased mobility. The fracture rate decreased in most. Orthopedic insertion of intramedullary rods was successful with maintenance of rod position. Mean osteocalcin levels fell from 35.5 +/- 5.6 microg/L to 28.4 +/- 4.1 microg/L (P <.03). Other bone turnover marker changes were not significant. The mean bone mineral density at lumbar spine increased from 0.5 +/- 0.08 to 0.67 +/- 0.03 g/cm(2) (P <.002) in children and 1.16 +/- 0.6 to 1.33 +/- 0.08 g/cm(2) in adults (P <.005). Other changes in bone mineral density were not significant. Cardiac output did not change significantly.

CONCLUSIONS

Pamidronate treatment is an effective therapeutic modality for children with polyostotic fibrous dysplasia, with a good short-term safety profile. Failure to demonstrate major biochemical or bone densitometry improvements is due to the nature of the fibrous dysplasia and intercurrent microfracture.

Bisphosphonates: from grandparents to grandchildren

Bisphosphonates are synthetic analogues of pyrophosphate that inhibit bone resorption by their action on osteoclasts. Bisphosphonates have been extensively used in the elderly with primary and secondary osteoporosis, Paget's disease, and hypercalcemia of malignancy. In recent years, bisphosphonates have been used to treat children acutely for resistant hypercalcemia and chronically for various metabolic bone diseases. The theoretical concerns of possible adverse effects of these drugs on the growing skeleton have not been proven to be true. In the present review, we have critically analyzed the available literature on bisphosphonate therapy in both adult and pediatric clinical trials. Although not yet approved by the FDA for use in children, bisphosphonates, from published experience, demonstrate benefit to the child with no serious adverse effects. Based on the literature analysis the review furnishes detailed recommendations and practical guidelines regarding the use of oral and intravenous bisphosphonates in children. Bisphosphonates might be the first agents to provide the pediatrician with an opportunity to treat mineral and bone disorders of childhood, which until recently did not have satisfactory therapy.

Clinical implications of genetic defects in G proteins: oncogenic mutations in G alpha s as the molecular basis for the McCune-Albright syndrome

Signal-transducing guanine nucleotide-binding proteins (G proteins) couple extracellular receptor proteins to intracellular effector enzymes and ion channels, and therefore are critical mediators of cellular responses to external stimuli. G proteins are comprised of three subunits (alpha, beta, gamma), each encoded by many different genes. The multiplicity of G protein subunits facilitates great combinatorial variability, which, in part, accounts for the ability of G proteins to interact with many different receptor and effector proteins. Hundreds of G protein-coupled receptors have been identified, and their unique patterns of expression among a restricted number of cell types contributes greatly to the apparent specificity of hormone action. Mutations that either activate or inactivate some of these receptors account for a number of highly specific syndromes, which affect a limited number of target tissues. By contrast, most G proteins are widely expressed in many tissues. Accordingly, mutations in these signaling molecules would be expected to produce a more generalized pattern of hormone dysfunction. Activating mutations in the gene (GNAS1) that encode the alpha subunit of the G protein that stimulates adenylyl cyclase (AC) have been identified in many endocrine neoplasms and diverse tissues of patients with McCune-Albright syndrome. The McCune-Albright syndrome is characterized by autonomous endocrine function, hyperpigmented skin lesions, and fibrous dysplasia of bone--effects which reflect the ability of CAMP to stimulate cell function and proliferation in a wide variety of tissues. The unusual features of the McCune-Albright syndrome are explained by the mosaic distribution of cells bearing the mutant allele, an observation that is most consistent with postzygotic mutation of GNAS1. Experimental analysis of this syndrome has extended our understanding of the clinical and biochemical consequences of dysfunctional G protein action and has provided a bench-to-bedside demonstration of the critical role that G proteins play in transmembrane signal transduction in humans.