Improvement of Fibrous Dysplasia After Burosumab Therapy in a Pediatric Patient with McCune-Albright Syndrome: A Case Report.

CASE: Burosumab is a novel drug developed to treat hereditary fibroblast growth factor 23 (FGF23)-related disorders. We report the case of an 11-year-old girl with McCune-Albright syndrome (MAS) who sustained hypophosphatemia due to excess FGF23 and multiple bone lesions of fibrous dysplasia (FD). Burosumab therapy markedly improved not only the biochemical parameters but also the radiographic appearance of the FD lesions and clinical symptoms. CONCLUSION: This is the first report to demonstrate that burosumab is effective in improving FD lesions in a patient with MAS.

RANK-L inhibitor as a promising agent for refractory extensive craniofacial fibrous dysplasia: A case report.

BACKGROUND: McCune-Albright syndrome is a rare disorder characterized by polyostotic fibrous dysplasia (FD), café-au-lait skin pigmentation, and endocrine dysfunction. Extensive FD in the craniofacial region can present significant challenges in terms of disease control and carries a high risk of permanent visual impairment. METHODS: We present a case of medically and surgically resistant FD that required nine optic nerve decompressions. RESULTS: The condition was ultimately controlled with the use of the denosumab agent. CONCLUSION: The case highlights the importance and potential efficacy of denosumab in resistant FD management, particularly in cases involving sensitive organs.

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.

Case Report: Severe McCune-Albright syndrome presenting with neonatal Cushing syndrome: navigating through clinical obstacles.

Background: Café-au-lait skin macules, Cushing syndrome (CS), hyperthyroidism, and liver and cardiac dysfunction are presenting features of neonatal McCune-Albright syndrome (MAS), CS being the rarest endocrine feature. Although spontaneous resolution of hypercortisolism has been reported, outcome is usually unfavorable. While a unified approach to diagnosis, treatment, and follow-up is lacking, herein successful treatment and long-term follow-up of a rare case is presented. Clinical case: An 11-day-old girl born small for gestational age presented with deterioration of well-being and weight loss. Large hyperpigmented macules on the trunk, hypertension, hyponatremia, hyperglycemia, and elevated liver enzymes were noted. ACTH-independent CS due to MAS was diagnosed. Although metyrapone (300 mg/m2/day) was started on the 25th day, complete remission could not be achieved despite increasing the dose up to 1,850 mg/m2/day. At 9 months, right total and left three-quarters adrenalectomy was performed. Cortisol decreased substantially, ACTH remained suppressed, rapid tapering of hydrocortisone to physiological dose was not tolerated, and supraphysiological doses were required for 2 months. GNAS analysis from the adrenal tissue showed a pathogenic heterozygous mutation. During 34 months of follow-up, in addition to CS due to MAS, fibrous dysplasia, hypophosphatemic rickets, and peripheral precocious puberty were detected. She is still regularly screened for other endocrinopathies. Conclusion: Neonatal CS due to MAS is extremely rare. Although there is no specific guideline for diagnosis, treatment, or follow-up, addressing side effects and identifying treatment outcomes will improve quality of life and survival.

Lesion Expansion in Gnathic Fibrous Dysplasia: Natural History, Indicators of Progression, and Response to Bisphosphonates.

Fibrous dysplasia (FD) is characterized by expansile fibro-osseous lesions that may occur in association with endocrinopathies as part of McCune-Albright syndrome (MAS). Craniofacial FD is a significant source of morbidity and most commonly involves the gnathic bones. There is a critical need to understand the natural history and risk factors for gnathic FD progression to develop preventative trials and identify candidates for intervention. The purpose of this study was to characterize gnathic FD lesion expansion and to identify risk factors associated with lesion growth. Patients with gnathic FD and serial CT imaging were evaluated. Volumetric analyses of CT scans were performed using MIM Encore software. Generalized mixed model analysis was used to account for intra-subject correlation, with FD lesion volume as the dependent variable. In addition to age, effects of MAS-associated endocrinopathies, sex, disease severity, and bisphosphonate treatment were evaluated. A total of 104 total lesions in 52 patients were characterized longitudinally. Median age at initial scan was 8.8 years (range 3.4-18.8), and median age at final scan was 16.8 years (range 6.9-33.4 years). The median number of scans per subject was 4 (range 2-14). FD lesion volume increased with age (2.50 cm3 /yr, 95% confidence interval [CI] 1.95-3.04, p < 0.001). However, lesion expansion rate decreased over time (-0.05 cm3 /yr, 95% CI -0.07 to 0.04, p < 0.001). Mandibular lesions tended to expand at a greater rate than maxillary lesions (p < 0.001). Growth hormone excess was associated with accelerated expansion rate (p = 0.002). Other MAS-associated endocrinopathies, pubertal status, sex, weight, lesion density, disease severity, and bisphosphonate treatment were not associated with lesion volume or expansion. Gnathic FD lesion expansion is most rapid in younger children and declines as patients approach adulthood. The availability of quantitative natural history data will guide clinicians in identifying patients who are candidates for medical and surgical interventions and clinical trials for preventative therapies. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

Denosumab use in bone fibrous dysplasia refractory to bisphosphonate: A retrospective multicentric study.

INTRODUCTION: Increased RANKL expression is observed in the bone tissue of fibrous dysplasia of bone/McCune-Albright syndrome (FD/MAS). In one animal model of FD/MAS, the inhibition of RANKL reduced tumor volume. A beneficial effect of denosumab on pain in patients refractory to bisphosphonates has been reported, but without systematic quantification of pain improvement. This work describes the clinical experience of our group on the efficacy on pain of denosumab treatment, along with safety, in FD/MAS patients refractory to bisphosphonates. MATERIALS AND METHODS: We have conducted a retrospective multicenter study in 6 academic rheumatology centers in France. We have collected patients and FD/MAS characteristics, duration of prior exposure to bisphosphonates, denosumab treatment modalities (dosage - administration regimen - number of courses); evolution of pain evaluated by Visual Analogic Scale (VAS). RESULTS: 13 patients were included (10 women and 3 men) 45 years on average, 5 MAS, 4 monostotic and 4 polyostotic forms. The average duration post-diagnosis of FD/MAS was 25 years and the mean duration of prior exposure to bisphosphonates was 4.7 years. Pain could be analyzed in 7 patients, showing a significant improvement from a mean VAS of 7.8 to 2.9 (-4.9 points, p = 0.003). In one patient with fronto-orbital FD/MAS, a 30 % decrease in lesional volume, assessed by MRI, was observed within 6 months of treatment, that was sustained over the following 12 months. Treatment regimens were heterogeneous. No hypercalcemia was observed after treatment cessation and the clinical tolerance was good. DISCUSSION: This study suggests that denosumab reduces pain in patients with DF/MAS refractory to bisphosphonates, and quantifies this improvement for the first time in a multicenter study. In our cohort, no patients who discontinued denosumab developed hypercalcemia and clinical tolerance was overall good. This study also provides encouraging data regarding lesion volume control. Further controlled studies are required to determine the place and modalities of the denosumab treatment of FD/MAS. CONCLUSION: Denosumab significantly decreased pain in FD/MAS refractory to bisphosphonate. This study paves the way for a randomized clinical trial to validate and standardize the prescription of denosumab in FD/MAS.

Clinical value of RANKL, OPG, IL-6 and sclerostin as biomarkers for fibrous dysplasia/McCune-Albright syndrome.

BACKGROUND: Fibrous dysplasia/McCune-Albright syndrome (FD/MAS) is a rare genetic bone disease caused by a somatic mutation in the GNAS gene. Currently used bone turnover markers (BTMs) do not correlate with the clinical picture and are not useful to predict or monitor therapy success. This study assessed the correlation of RANKL, OPG, RANKL/OPG ratio, IL-6 and sclerostin with the classic BTMs alkaline phosphatase (ALP), procollagen type 1 propeptide (P1NP) and beta crosslaps (CTX), with pain, skeletal burden score (SBS) and response to bisphosphonate or denosumab treatment. METHODS: Ninety-six serum samples of adult patients >18 years of age with any subtype of FD/MAS were included from the biobank facility of the Leiden University Medical Center, Center for Bone Quality between 2015 and 2021. Standard laboratory assessments were assessed as part of usual care. The concentrations of potential biomarkers RANKL, OPG, sclerostin, IL-6 were analyzed. Data on FD/MAS subtype, age, pain, treatment history and treatment response were retrieved from the electronic patient files. Baseline characteristics were summarized by descriptive statistics. Correlations of the concentrations of the potential biomarkers with classic bone turnover markers, SBS and pain scores were cross-sectionally assessed by Spearman rank order correlation. Correction for multiple testing was performed by Benjamini and Hochberg False Discovery Rate. A sensitivity analyses was performed by excluding patients with SBS below 15 and patients using antiresorptive medication at the time of blood withdrawal or within the wash-out period. In patients treated with bisphosphonates or denosumab after blood withdrawal, pre-treatment concentrations were compared in patients with and without therapy response by Mann Whitney U test. RESULTS: The median age of the patients was 41.2 (Q1-Q3 25.9-52.2) years, 62.5 % was female. Median SBS was 2.5 (Q1-Q3 0.5-7.8). RANKL level correlated weakly with ALP (Spearman rho 0.309, p = 0.004, n = 84), but not with P1NP or CTX. The RANKL/OPG ratio, OPG, IL-6 and sclerostin did not correlate with ALP, P1NP or CTX. None of the potential biomarkers correlated with SBS or pain. Results of the sensitivity analyses were comparable. Pre-treatment biomarker levels were similar in patients with and without improvement in pain scores following bisphosphonate therapy. Pre-treatment RANKL and sclerostin were comparable between patients with and without improvement in pain scores after denosumab therapy. Pre-treatment IL-6 level and the RANKL/OPG ratio seemed to be higher in patients with response to denosumab (IL-6: median 0.64 (Q1-Q3 0.53-0.74) pg/mL, n = 6, RANKL/OPG: median 0.062 (Q1-Q3 0.016-0.331), n = 5) compared to patients without response (IL-6: median 0.35 (0.20-0.54) pg/mL, n = 5, RANKL/OPG: 0.027 (0.024-0.046), n = 4). Pre-treatment IL-6 correlated with the improvement in maximum pain scores (rho 0.962, p < 0.001, n = 9) and average pain scores (rho 0.895, p = 0.001, n = 9) reported during denosumab therapy. CONCLUSION: Increased concentrations of RANKL, IL-6, sclerostin and of the RANKL/OPG ratio do not indicate severity of FD/MAS, as no correlation was observed of these potential biomarkers with the classic BTMs and SBS. Biomarker levels did not correlate with pain and had no value in predicting bisphosphonate treatment response. These biomarkers are not superior over the currently used methods of assessing ALP, P1NP and CTX or evaluating SBS to establish disease extent or activity and provide no reliable results. Yet, possibly pre-treatment IL-6 and the RANKL/OPG ratio may have some predictive value for clinical response to denosumab. Therefore, studies investigating disease activity and treatment response should include lesional imaging and patient-reported outcome measures.

Autonomous growth hormone secretion due to McCune Albright syndrome in paediatric age group: an ominous triad.

PURPOSE: The current study aimed to report cases of McCune Albright syndrome (MAS) with growth hormone (GH) hyper secretion along with a systematic review of literature to elucidate challenges and intricacies in its diagnosis and management. METHODS: It was a single centre study carried out in individuals with MAS and autonomous GH secretion (AGHS). In addition, a systematic search of literature across three databases (PubMed, Scopus and EMBASE) was performed from inception until May 31, 2021 to identify cases of MAS with AGHS in the pediatric age group (<18 years). RESULTS: Three cases from authors centre and 42 cases identified from systematic literature review were analysed. Precocious puberty was the most common presenting endocrinopathy seen in 56.8% (25/44) cases, followed by hyperthyroidism (10/45), hypophosphatemia (4/45), and hypercortisolism (2/45). Cranio-facial fibrous dysplasia (CFFD) was seen in all while polyostotic fibrous dysplasia and Café au lait macule was seen in 40/45 (88.9%) and 35/45 (77.8%), respectively. Pituitary adenoma (58.3% microadenoma) was localized in 53.3% (24/45) cases on pituitary imaging. Biochemical and clinical remission of AGHS was achieved in 61.5% (24/45) cases with medical therapy. CONCLUSION: Diagnosing AGHS in MAS is challenging because of concomitant presence of CFFD, non-GH endocrinopathies associated height spurt and elevated serum IGF-1. GH-GTT should be performed in presence of elevated growth velocity and serum IGF-1 (>1 X ULN) despite adequate control of non-GH endocrinopathies. Medical management can lead to disease control in substantial number of cases and often entails use of multiple agents.

Pharmacological Interventions Targeting Pain in Fibrous Dysplasia/McCune-Albright Syndrome.

Fibrous dysplasia (FD) is a rare, non-inherited bone disease occurring following a somatic gain-of-function R201 missense mutation of the guanine-nucleotide binding protein alpha subunit stimulating activity polypeptide 1 (GNAS) gene. The spectrum of the disease ranges from a single FD lesion to a combination with extraskeletal features; an amalgamation with café-au-lait skin hyperpigmentation, precocious puberty, and other endocrinopathies defines McCune-Albright Syndrome (MAS). Pain in FD/MAS represents one of the most prominent aspects of the disease and one of the most challenging to treat-an outcome driven by (i) the heterogeneous nature of FD/MAS, (ii) the variable presentation of pain phenotypes (i.e., craniofacial vs. musculoskeletal pain), (iii) a lack of studies probing pain mechanisms, and (iv) a lack of rigorously validated analgesic strategies in FD/MAS. At present, a range of pharmacotherapies are prescribed to patients with FD/MAS to mitigate skeletal disease activity, as well as pain. We analyze evidence guiding the current use of bisphosphonates, denosumab, and other therapies in FD/MAS, and also discuss the potential underlying pharmacological mechanisms by which pain relief may be achieved. Furthermore, we highlight the range of presentation of pain in individual cases of FD/MAS to further describe the difficulties associated with employing effective pain treatment in FD/MAS. Potential next steps toward identifying and validating effective pain treatments in FD/MAS are discussed, such as employing randomized control trials and probing new pain pathways in this rare bone disease.

[The experience of interdisciplinary interaction in elimination of midface deformation (clinical observation)]. / Opyt mezhdistsiplinarnogo vzaimodeistviya pri ustranenii deformatsii srednei zony litsa (klinicheskoe nablyudenie).

Fibrous dysplasia is a hamartoma appearing as a benign pathologic process in which normal bone tissue formation is replaced by overgrowth of fibrous connective tissue. The problem of diagnosis and treatment of patients with fibrous dysplasia remains unsolved in the absence of a uniform understanding of its etiology and pathogenesis. Treatment and rehabilitation of patients with midface fibrous dysplasia is a complicated medico-social problem, which requires interaction of specialists of different fields to resolve it. The disease presents a practical interest for doctors of more than 20 specialties, as it can lead to disability. The present article describes a clinical case of interdisciplinary interaction of specialists in the fields of maxillofacial surgery, ophthalmology, otorhinolaryngology, plastic surgery and radiology involved in complex treatment of a patient with midface fibrous dysplasia accompanied by eyeball dislocation, decreased vision, as well as progressive impairment of nasal breathing function. The performed treatment resulted in favorable functional and aesthetic outcomes including elimination of exophthalmos, vertical strabismus, lacrimation disorders, nasal breathing disorders, increase of visual acuity and improvement of external appearance.

Risk of developing spontaneous MRONJ in fibrous dysplasia patients treated with bisphosphonates: a systematic review of the literature.

OBJECTIVE: The objective of this systematic review was to evaluate the risks of medication-related osteonecrosis of the jaw (MRONJ) in fibrous dysplasia (FD) and McCune-Albright syndrome (MAS) patients treated with bisphosphonates. METHOD AND MATERIALS: A systematic review of the literature was performed by searching PubMed and Embase databases using MeSH terms (fibrous dysplasia of bone, "fibrous dysplasia, polyostotic," osteonecrosis, jaw, therapeutics, diphosphonates, denosumab, teriparatide, estrogens, hormones, raloxifene hydrochloride, calcitonin, cathepsin K) and non-MeSH terms (antiresorptive therapy, antiresorptives, bisphosphonate, estrogen therapy, hormone therapy, bazedoxifene, cathepsin K inhibitor). Articles were limited to human studies, in English language, in which patients were on antiresorptives for at least 1 year. PRISMA statement guidelines were used to eliminate non-relevant studies. The PICOT question asked was, "Does exposure to bisphosphonates and other antiresorptives cause occurrence of MRONJ in fibrous dysplasia and fibrous dysplasia/McCune-Albright syndrome patients followed up for at least 1 year?" RESULTS: Eight eligible articles were included in the quantitative synthesis after articles were screened using a PRISMA flowchart. There were 12 reported occurrences of MRONJ among a combined total of 312 fibrous dysplasia and fibrous dysplasia/McCune-Albright syndrome patients (3.85%). CONCLUSION: Patients with fibrous dysplasia or fibrous dysplasia/McCune-Albright syndrome have a low incidence of MRONJ and may apparently have low susceptibility to spontaneous development of MRONJ.

Effects of zoledronic acid therapy in fibrous dysplasia of bone: a single-center experience.

Objective: Fibrous dysplasia (FD) is a rare bone disorder that can involve any part of the skeleton, leading to bone pain, deformities, and fractures. Treatment with intravenous bisphosphonates has been used with variable results. Therefore, we aimed to evaluate the effects of zoledronic acid (ZA) therapy in patients with monostotic or polyostotic FD. Methods: The medical records of thirteen patients with FD evaluated between 2015 and 2020 were retrospectively analyzed. In the subgroup of patients treated with ZA (n = 7), data on pain relief, changes in bone turnover markers (BTMs), and adverse events following ZA infusions were retrieved. Moreover, radiological changes in response to treatment were recorded in patients who underwent radiological follow-up. Results: Of the patients, 5 (38%) presented with monostotic whereas 8 (62%) had polyostotic FD. Bone pain was a common finding (69%), and most patients (62%) exhibited elevated baseline BTMs. Partial or complete pain relief was reported in 6 of 7 patients treated with ZA. BTMs, especially C-telopeptide of type I collagen (CTX), significantly decreased after therapy (change rate: -61.8% [IQR -71, -60%]), and median CTX levels were significantly lower than at baseline (0.296 ng/mL [0.216, 0.298] vs. 0.742 ng/mL [0.549, 0.907], respectively; P = 0.04). No radiological improvement was observed in cases with radiological follow-up (n = 3). No serious adverse effects of ZA were reported. Conclusion: ZA treatment was well tolerated and provided beneficial effects in relieving bone pain and reducing BTMs, especially CTX. Our data reinforce the role of ZA in the treatment of FD-related bone pain.

Neuropathic-like Pain in Fibrous Dysplasia/McCune-Albright Syndrome.

CONTEXT: Pain is a major symptom in adults with fibrous dysplasia/McCune-Albright syndrome (FD/MAS) and response to current treatments, including bisphosphonates and standard analgesics (nonsteroidal anti-inflammatory drugs and opiates) is unpredictable. No studies have explored whether the type of pain is variable in this patient group. OBJECTIVE: To determine the frequency of neuropathic-like pain in patients with FD/MAS. DESIGN: Retrospective, dual registry study. SETTING: Community. PATIENTS: FD/MAS online registries: the US-based Familial Dysautonomia Foundation (FDF) and the UK-based Rare and Undiagnosed Diseases (RUDY) study. INTERVENTION: Subjects completed questionnaires to evaluate the presence of features of neuropathic-like pain (painDETECT) and the impact on sleep quality (Pittsburgh Sleep Quality Index) and mental health (Hospital Anxiety and Depression Scale). Descriptive statistics were used to characterize the prevalence and associated burden of neuropathic-like pain. MAIN OUTCOME MEASURES: Incidence of neuropathic, nociceptive, and unclear pain. RESULTS: Of 249 participants, one third experienced neuropathic-like pain. This group had statistically significantly (P < 0.001) worse mental well-being and sleep in comparison to those with predominately nociceptive pain. CONCLUSIONS: Neuropathic-like pain is common in patients with FD/MAS and associated with worse quality of life. Evaluation of pain in patients with FD/MAS should include assessment of neuropathic-like pain to guide personalized approaches to treatment and inform future research.

Inhibition of IL-6 in the treatment of fibrous dysplasia of bone: The randomized double-blind placebo-controlled TOCIDYS trial.

Increased interleukin-6 (IL-6) has been observed in the bone tissue of fibrous dysplasia of bone/McCune-Albright syndrome (FD/MAS) and is possibly involved in the increased bone destruction and bone pain characterizing this disease. The TOCIDYS trial was a randomized, placebo-controlled, 1 year, cross-over, proof-of-concept trial, conducted in patients not responding to bisphosphonates, using monthly intra-venous tocilizumab (a monoclonal antibody to the IL-6 receptor) at 8 mg/kg or a matching placebo for 6 months. Over the following 6 months, they received tocilizumab if they first had placebo, and vice-versa. We measured change in serum CTX after 6 months of treatment, compared with baseline (primary endpoint). Other endpoints were the change in bone pain, change in P1NP, bone alkaline phosphatase, osteocalcin and ICTP, and variation of quality of life. The analysis relied on ANOVA, with sequence of treatment, period and treatment as factors and accounting for a potential carry-over effect. We have randomized 8 patients with FD/MAS in each sequence who all completed the first 6 months treatment period. During the second 6 months period, 3 patients stopped therapy, so the efficacy analysis set included 13 patients. We observed no significant change in serum CTX and other biochemical markers of bone turnover between the tocilizumab and placebo groups. There was no significant change in the level of bone pain on tocilizumab, although 3 patients had a sharp decrease in pain while on active drug, with progressive relapse on placebo for 2 of them, but with some degree of improvement in a few patients while on placebo. The SF-36 quality of life scale was not significantly changed. We conclude that tocilizumab does not decrease bone turnover in FD/MAS when administered in patients who fail to respond to bisphosphonates. Tocilizumab does not reduce bone pain in most patients, but a substantial effect in a subset cannot be ruled out in this trial powered for markers but not for pain.

Safety of therapy with and withdrawal from denosumab in fibrous dysplasia and McCune-Albright syndrome: an observational study.

Denosumab (Dmab) treatment can benefit patients with fibrous dysplasia/McCune-Albright syndrome (FD/MAS) by suppressing the receptor activator of nuclear factor κB ligand (RANKL)-mediated increased bone resorption. However, limited data of two pediatric cases indicate that a rebound phenomenon may occur after withdrawal. Therefore we studied the safety of Dmab discontinuation in FD/MAS. Thirty-seven patients using Dmab, mostly after unsuccessful bisphosphonate (BP) treatment, were included. Health records were screened for pain scores, side effects, and bone turnover markers (BTMs) (calcium, alkaline phosphatase [ALP], procollagen 1 N-terminal propeptide [P1NP], and ß-crosslaps [B-CTX, also termed ß-C-terminal telopeptide]) during treatment, and for BTMs and clinical rebound effects after withdrawal. BTM levels after withdrawal were compared to pretreatment values. Data were calculated as median (interquartile range [IQR]). BTMs normalized in two-thirds of patients and pain scores decreased significantly during treatment (p = 0.002). One patient (2.7%) developed osteonecrosis of the jaw. Sixteen patients discontinued Dmab treatment after a median of 1.6 years (IQR 1.0 years) because of insufficient effect on pain (n = 10, 63%), side effects (n = 4, 25%), or other reasons (n = 4, 25%). Follow-up posttreatment was 3.2 (2.8) years, wherein no fractures, pain flares, or lesion progression occurred. Calcium remained normal in all but one patient, who had a mild asymptomatic hypercalcemia (2.73 mmol/L) 5 months after discontinuation. ALP passed pretreatment levels in five of 11 patients (46%), increased most after 6 months by 18 (43) U/L, and returned to baseline levels thereafter. P1NP exceeded pretreatment levels in four of nine patients (44%), CTX in eight of nine patients (89%). P1NP rose most after 3 months and stabilized thereafter. CTX showed the highest relative elevation. Patients with high pretreatment levels responding well to Dmab seemed to have the highest rebound. These results suggest beneficial effects of Dmab on pain and BTMs, and show a biochemical but asymptomatic rebound phenomenon after withdrawal in adults with FD/MAS, mainly in case of high pretreatment levels, good response, and multiple injections. Further studies on the safety of Dmab and withdrawal are needed and ongoing. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Denosumab Reduces Lesional Fluoride Skeletal Burden on Na[18F]F PET-CT in Patients With Fibrous Dysplasia/McCune-Albright Syndrome.

CONTEXT: The correlation between fibrous dysplasia/McCune-Albright syndrome (FD/MAS) skeletal disease burden on Na[18F]F positron emission tomography-computed tomography (PET-CT) and serum bone turnover markers (BTMs) was recently described. The effect of treatment on lesional fluoride burden in FD/MAS is unknown. OBJECTIVE: To investigate treatment response measurements in patients with FD/MAS who underwent Na[18F]F-PET-CT and treatment with antiresorptives. METHODS: Observational case series at an academic center of expertise for rare bone diseases. Fifteen consecutive patients were observed with FD/MAS with baseline and follow-up Na[18F]F-PET-CT parameters of healthy bone and FD lesions, BTMs, and pain scores at start of denosumab (n = 8) treatment and non-denosumab patients (n = 7). On Na[18F]F-PET-CT the volumetric measures of FD burden (fluoride tumor volume [FTV]) and "fraction affected skeleton" (FAS) represented the portion of the skeleton affected. This was correlated with BTMs and pain. RESULTS: Disease activity decreased significantly, with FTV 361 cm3 to 97 cm3 (P = .018) in denosumab-treated patients, but not in non-denosumab patients (P = .249). Serum P1NP and alkaline phosphatase (ALP) decreased significantly: 82 ng/mL vs 55 ng/mL (P = .023) and 119 IU/L vs 84 IU/L (P = .020), respectively. In denosumab-treated patients pain scores improved leading to pain medication reduction. This correlated with lesional uptake, but healthy bone activity did not change. BTMs and FTV correlated positively (P1NP r = 0.730, P < .001; and ALP r = 0.406, P = .006), as did change in BTMs and FTV: P1NP (P = 0.032) and ALP (P = 0.024). FAS strongly correlated with treatment-induced decrease in ALP (P = .027) and P1NP (P = .009). CONCLUSION: Na[18F]F-PET-CT captured treatment-induced lesional changes which correlated with BTMs and pain reduction. Therefore Na[18F]F-PET-CT can be used as an objective local parameter of response to denosumab treatment in FD/MAS.

First radiobiological characterization of the McCune-Albright syndrome: influence of the ATM protein and effect of statins + bisphosphonates treatment.

PURPOSE: MacCune-Albright syndrome (MAS) is a rare autosomal dominant osteo-hormonal disorder. MAS is characterized by a severe form of polyostotic fibrous dysplasia, 'café-au-lait' pigmentation of the skin and multiple endocrinopathies. MAS was shown to be caused by mosaic missense somatic mutations in the GNAS gene coding for the alpha-subunit of the stimulatory G-protein. MAS is also associated with radiation-induced malignant tumors, like osteosarcoma, fibrosarcoma and chondrosarcoma but their origin remains misunderstood. In parallel, bisphosphonates treatment was shown to improve the MAS patients' outcome, notably by increasing bone density but, again, the molecular mechanisms supporting these observations remain misunderstood. MATERIALS AND METHODS: Here, by using fibroblast and osteoblast cell lines derived from 2 MAS patients, the major radiobiological features of MAS were investigated. Notably, the clonogenic cell survival, the micronuclei and the γH2AX, pATM and MRE11 immunofluorescence assays were applied to MAS cells. RESULTS: It appears that cells from the 2 MAS patients are associated with a moderate but significant radiosensitivity, a delayed radiation-induced nucleoshuttling of the ATM kinase likely caused by its sequestration in cytoplasm, suggesting impaired DNA double-strand breaks (DSB) repair and signaling in both fibroblasts and osteoblasts. Such delay may be partially corrected by using bisphosphonates combined with statins, which renders cells more radioresistant. CONCLUSIONS: Our findings represent the first radiobiological characterization of fibroblasts and osteoblasts providing from MAS patients. Although the number of studied cases is reduced, our findings suggest that the MAS cells tested belong to the group of syndromes associated with moderate but significant radiosensitivity. Further investigations are however required to secure the clinical transfer of the combination of bisphosphonates and statins, to reduce the disease progression and to better evaluate the potential risks linked to radiation exposure.

Denosumab in Patients With Fibrous Dysplasia Previously Treated With Bisphosphonates.

CONTEXT: Fibrous dysplasia/McCune-Albright syndrome (FD/MAS) is a rare bone disorder commonly treated with bisphosphonates, but clinical and biochemical responses may be incomplete. OBJECTIVE: To evaluate the efficacy and tolerability of the receptor activator of nuclear factor-κB ligand inhibitor denosumab in the treatment of patients with FD/MAS refractory to bisphosphonate therapy. DESIGN: Case series. SETTING: Academic center of expertise for rare bone diseases. PATIENTS: Data were collected from 12 consecutive patients with FD/MAS with persistent pain and increased biochemical markers of bone turnover (BTMs) after long-term treatment with bisphosphonates (median, 8.8 years) and were treated with subcutaneous denosumab 60 mg at 3- or 6-month intervals with a follow-up for at least 12 months. MAIN OUTCOME(S): Sustained reduction of BTMs and bone pain. RESULTS: A 60 mg dose of denosumab once every 3 months, but not once every 6 months, induced a sustained reduction of BTMs. After a median treatment period of 15.5 months (range, 12 to 19) serum alkaline phosphatase activity and propeptide of type 1 procollagen levels were respectively reduced from 212 ± 39.4 IU/L to 79 ± 6.0 IU/L (P = 0.004) and from 346.2 ± 111.1 ng/mL to 55.7 ± 16.6 ng/mL (P = 0.023) and normalized in 70% and 75% of patients, respectively. Although not quantitavely measured, 10 patients reported a reduction in bone pain of whom 6 reported complete elimination of pain. Treatment with denosumab was well tolerated. CONCLUSION: Our results indicate that 60 mg of denosumab every 3 months is a promising, well-tolerated treatment of most patients with FD/MAS refractory to bisphosphonate therapy. These results together with those of previously published case reports provide the necessary background for the design of a larger, controlled study.

McCune Albright syndrome: an endocrine medley.

McCune Albright syndromeis a rare disorder that presents with multiple endocrine abnormalities. We report the case of a 24-year-old woman who presented with right lower limb pain, with no preceding trauma or fracture. On examination she was noted to have coarsened facial features, acral enlargement, bitemporal hemianopia, galactorrhoea and multiple café-au-lait macules. She gave history of precocious puberty, having attained menarche at 7 years of age. Biochemical investigations revealed hyperprolactinaemia, with unsuppressed growth hormone levels following a glucose load and subclinical hyperthyroidism. Technetium-99m methylene diphosphonate bone scan showed polyostotic fibrous dysplasia, MRI of the brain showed a pituitary macroadenoma. Thus she was diagnosed to have McCune Albright syndrome with multiple endocrine manifestations. She was treated with parenteral zoledronate for her bony lesions and initiated on cabergoline for plurihormonal pituitary macroadenoma. She is planned to be on close follow-up to assess for clinical improvement and appearance of other manifestations.

Hepatic Lesions Associated With McCune Albright Syndrome.

McCune-Albright syndrome (MAS) results from a GNAS gene mutation. It is associated with café au lait macules, fibrous dysplasia, and several endocrinopathies to include gonadotropin-independent precocious puberty, growth hormone excess, Cushing syndrome, thyroid disease, and renal phosphate wasting. It is recognized to be a rare cause of neonatal cholestasis. We describe the hepatic outcome of 3 children with MAS referred to a single national liver unit. All presented with high gamma-glutamyl transpeptidase cholestasis and hepatitis. Cholestasis resolved by 1 year; but hepatic inflammation persisted, and 2 children developed progressive atypical focal nodular hyperplasia and 1 developed hepatoblastoma. This the first reported malignant hepatic lesion associated with MAS. MAS should be considered part of the differential diagnosis of neonatal cholestasis and affected children should be closely monitored for the development of hepatic lesions with regular liver ultrasound and alpha fetoprotein level.