First-in-class humanized FSH blocking antibody targets bone and fat.

Blocking the action of FSH genetically or pharmacologically in mice reduces body fat, lowers serum cholesterol, and increases bone mass, making an anti-FSH agent a potential therapeutic for three global epidemics: obesity, osteoporosis, and hypercholesterolemia. Here, we report the generation, structure, and function of a first-in-class, fully humanized, epitope-specific FSH blocking antibody with a KD of 7 nM. Protein thermal shift, molecular dynamics, and fine mapping of the FSH-FSH receptor interface confirm stable binding of the Fab domain to two of five receptor-interacting residues of the FSHß subunit, which is sufficient to block its interaction with the FSH receptor. In doing so, the humanized antibody profoundly inhibited FSH action in cell-based assays, a prelude to further preclinical and clinical testing.

Severity of reduced bone mineral density and risk of fractures in long-term survivors of childhood leukemia and lymphoma undergoing guideline-recommended surveillance for bone health.

BACKGROUND: Survivors of childhood leukemia/lymphoma are at increased risk for reduced bone mineral density (BMD). The authors sought to determine the frequency of reduced BMD detected by off-therapy surveillance, factors associated with reduced BMD, and the association of reduced BMD with fractures. METHODS: This cross-sectional study included childhood leukemia/lymphoma survivors attending 2 survivorship clinics who received guideline-recommended BMD surveillance ≥2 years post-therapy with dual-energy x-ray absorptiometry (from January 1, 2004 to August 31, 2016). Lumbar spine BMD z-scores were height-for-age-adjusted. Low and very low BMD were >1 SD and >2 SDs below norms, respectively. Treatment, chronic conditions, and fractures were abstracted from medical records. Logistic regression was used to examine the association of low BMD with patient/treatment factors and fractures. RESULTS: In total, 542 patients (51.5% female) with a mean age of 15.5 years (range, 4.4-52.2 years) who were 6 years post-therapy (range, 2.0-35.1 years) were evaluated, including 116 who reported post-therapy fractures. Lumbar spine low BMD was identified in 17.2% of survivors, and very low BMD was identified in 3.5% of survivors, but frequencies varied considerably between subgroups; 10.8% of survivors aged 15 to 19 years at diagnosis had very low BMD. In multivariable analyses, older age at diagnosis, white race, and being underweight were significantly associated with low BMD. Survivors with low BMD had greater odds of nondigit fractures (odds ratio, 2.2; 95% CI, 1.3-3.7) and specifically long-bone fractures (odds ratio, 2.7; 95% CI, 1.5-4.7). CONCLUSIONS: In this study of childhood leukemia/lymphoma survivors undergoing guideline-recommended dual-energy x-ray absorptiometry surveillance, patients who were older at diagnosis, white, and underweight were at the highest risk for lumbar spine low BMD. Low BMD was associated with a greater risk of fractures, emphasizing the clinical importance of surveillance.

Impaired Bone Mineral Density in Pediatric Patients with Chronic Graft-versus-Host Disease.

Pediatric allogeneic hematopoietic stem cell transplantation (AHSCT) recipients with chronic graft-versus-host disease (cGVHD) are at high risk for endocrinopathies, particularly impaired bone mineral density (BMD). However, rates of BMD impairment in pediatric AHSCT recipients with cGVHD have not been well documented. We report 33 patients with cGVHD who were referred to the National Institutes of Health (NIH) for the Natural History of Clinical and Biological Factors Determining Outcomes in Chronic Graft-versus-Host Disease Study (NCT 0092235) and underwent formal BMD assessment via dual-energy X-ray absorptiometry (DEXA). Not surprisingly, we found much higher rates of BMD impairment than previously reported for pediatric AHSCT recipients who were not stratified by the presence or absence of cGVHD. Most of these patients (73%) had a z-score ≤-2 in at least 1 anatomic site. Although we expected the rate to be higher than that observed for pediatric AHSCT recipients in studies that did not analyze patients with cGVHD separately, this rate is nonetheless extremely high. Furthermore, the overall rate of occult vertebral compression fractures (VCFs) in our cohort was 17%, and the rate was 23% in patients with at least 1 z-score of ≤-2. The rates of BMD impairment and VCF in our pediatric cohort were significantly higher than those seen in the adult AHSCT recipients who were concurrently enrolled on the same study at the NIH and had similar cGVHD severity. We found that older age at cGVHD diagnosis and a greater number of systemic therapies were associated with occult VCF. Moreover, the intensity of current immunosuppression negatively impacted lumbar spine and total hip BMD in this cohort. Our study, although limited by small patient numbers and lack of a control AHSCT recipient group without cGVHD, indicates that children with cGVHD are at a greater risk for BMD impairment than previously appreciated. Given the rising incidence of cGVHD in AHSCT recipients and our findings, we recommend that pre-AHSCT DEXA be incorporated into routine pediatric pretransplantation screening studies. A baseline DEXA study could facilitate longitudinal monitoring of BMD in children, who may be more susceptible than adults to the negative effects of AHSCT on BMD. In addition, given the high risk of BMD impairment in pediatric AHSCT recipients with cGVHD, such patients should undergo BMD evaluation upon developing cGVHD, with continued monitoring thereafter to allow intervention before progression of the BMD impairment to its severe manifestation, VCF.

Fibrous Dysplasia/McCune-Albright Syndrome: Clinical and Translational Perspectives.

Fibrous dysplasia (FD) is an uncommon and debilitating skeletal disorder resulting in fractures, deformity, functional impairment, and pain. It arises from post-zygotic somatic activating mutations in GNAS, in the cAMP-regulating transcript α-subunit, Gsα. Constitutive Gs signaling results in activation of adenylyl cyclase and dysregulated cAMP production. In the skeleton, this leads to the development of FD lesions with abnormal bone matrix, trabeculae, and collagen, produced by undifferentiated mesenchymal cells. FD may occur in isolation or in combination with extraskeletal manifestations, including hyperfunctioning endocrinopathies and café-au-lait macules, termed McCune-Albright syndrome (MAS). This review summarizes current clinical and translational perspectives in FD/MAS, with an emphasis on FD pathogenesis, natural history, pre-clinical and clinical investigation, and future directions.

Optimizing a therapeutic humanized follicle-stimulating hormone-blocking antibody formulation by protein thermal shift assay.

Biopharmaceutical products are formulated using several Food and Drug Administration (FDA) approved excipients within the inactive ingredient limit to maintain their storage stability and shelf life. Here, we have screened and optimized different sets of excipient combinations to yield a thermally stable formulation for the humanized follicle-stimulating hormone (FSH)-blocking antibody, MS-Hu6. We used a protein thermal shift assay in which rising temperatures resulted in the maximal unfolding of the protein at the melting temperature (Tm ). To determine the buffer and pH for a stable solution, four different buffers with a pH range from 3 to 8 were screened. This resulted in maximal Tm s at pH 5.62 for Fab in phosphate buffer and at pH 6.85 for Fc in histidine buffer. Upon testing a range of salt concentrations, MS-Hu6 was found to be more stable at lower concentrations, likely due to reduced hydrophobic effects. Molecular dynamics simulations revealed a higher root-mean-square deviation with 1 mM than with 100 mM salt, indicating enhanced stability, as noted experimentally. Among the stabilizers tested, Tween 20 was found to yield the highest Tm and reversed the salt effect. Among several polyols/sugars, trehalose and sucrose were found to produce higher thermal stabilities. Finally, binding of recombinant human FSH to MS-Hu6 in a final formulation (20 mM phosphate buffer, 1 mM NaCl, 0.001% w/v Tween 20, and 260 mM trehalose) resulted in a thermal shift (increase in Tm ) for the Fab, but expectedly not in the Fc domain. Given that we used a low dose of MS-Hu6 (1 µM), the next challenge would be to determine whether 100-fold higher, industry-standard concentrations are equally stable.

FSH-blocking therapeutic for osteoporosis.

Pharmacological and genetic studies over the past decade have established the follicle-stimulating hormone (FSH) as an actionable target for diseases affecting millions, namely osteoporosis, obesity, and Alzheimer's disease. Blocking FSH action prevents bone loss, fat gain, and neurodegeneration in mice. We recently developed a first-in-class, humanized, epitope-specific FSH-blocking antibody, MS-Hu6, with a KD of 7.52 nM. Using a Good Laboratory Practice (GLP)-compliant platform, we now report the efficacy of MS-Hu6 in preventing and treating osteoporosis in mice and parameters of acute safety in monkeys. Biodistribution studies using 89Zr-labeled, biotinylated or unconjugated MS-Hu6 in mice and monkeys showed localization to bone and bone marrow. The MS-Hu6 displayed a ß phase t½ of 7.5 days (180 hr) in humanized Tg32 mice. We tested 217 variations of excipients using the protein thermal shift assay to generate a final formulation that rendered MS-Hu6 stable in solution upon freeze-thaw and at different temperatures, with minimal aggregation, and without self-, cross-, or hydrophobic interactions or appreciable binding to relevant human antigens. The MS-Hu6 showed the same level of "humanness" as human IgG1 in silico and was non-immunogenic in ELISpot assays for IL-2 and IFN-γ in human peripheral blood mononuclear cell cultures. We conclude that MS-Hu6 is efficacious, durable, and manufacturable, and is therefore poised for future human testing.

Diagnosis and Management of Tumor-induced Osteomalacia: Perspectives From Clinical Experience.

PURPOSE: Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome of abnormal phosphate and vitamin D metabolism caused by typically small endocrine tumors that secrete fibroblast growth factor 23 (FGF23). TIO is characterized clinically by progressive musculoskeletal pain, fatigue, proximal muscle weakness, and multiple fractures, leading to long-term disability. Misdiagnosis and delayed diagnosis are common because of the nonspecific symptoms, and several years may elapse before patients receive an accurate diagnosis and appropriate treatment. Thus, it is vital that awareness of the appropriate recognition and management of TIO is increased among healthcare professionals who may encounter patients with suspected TIO. METHODS: A roundtable meeting was held on 10 January 2020 in Dallas, TX, USA, to gather perspectives on the diagnosis and treatment of TIO. The following topics were considered: clinical presentation, patient history, differential diagnosis, laboratory assessment, imaging, venous sampling, and treatment. RESULTS: This report provides a summary of our collective experiences in the management of TIO. MAIN CONCLUSIONS: Laboratory tests are mandatory to expedite TIO diagnosis and should include measurement of fasting serum phosphorus, renal phosphate reabsorption, serum 1,25-dihydroxyvitamin D, and serum FGF23 levels. Functional and anatomical imaging are essential to locate the FGF23-secreting tumor(s) causing TIO. Surgical resection is often a curative treatment when the tumor can be localized; however, better management of patients who cannot be operated on with targeted therapies is needed. Further efforts to increase awareness of TIO within the medical community, and education on recommended diagnostic and treatment pathways are required to improve the management of this debilitating disease.

Clinical and Radiographic Gastrointestinal Abnormalities in McCune-Albright Syndrome.

Context: McCune-Albright syndrome (MAS) is a rare disorder characterized by fibrous dysplasia of bone, café-au-lait macules, and hyperfunctioning endocrinopathies. It arises from somatic gain-of-function mutations in GNAS, which encodes the cAMP-regulating protein Gαs. Somatic GNAS mutations have been reported in intraductal papillary mucinous neoplasms (IPMNs) and various gastrointestinal (GI) tumors. The clinical spectrum and prevalence of MAS-associated GI disease is not well established. Objective: Define the spectrum and prevalence of MAS-associated GI pathology in a large cohort of patients with MAS. Design: Cross-sectional study. Setting: National Institutes of Health Clinical Center and The Johns Hopkins Hospital. Methods: Fifty-four consecutive subjects with MAS (28 males; age range, 7 to 67 years) were screened with magnetic resonance cholangiopancreatography (MRCP). Results: Thirty of 54 subjects (56%) had radiographic GI abnormalities. Twenty-five (46%) of the screened subjects had IPMNs (mean age of 35.1 years). Fourteen of the 25 had IPMNs alone, and 11 had IPMNs and abnormal hepatobiliary imaging. The 30 patients with MAS-associated GI pathology had a higher prevalence of acute pancreatitis, diabetes mellitus, and skeletal disease burden of fibrous dysplasia than patients without GI disease. Conclusions: A broad spectrum of GI pathology is associated with MAS. IPMNs are common and occur at a younger age than in the general population. Patients with MAS should be considered for screening with a focused GI history and baseline MRCP. Further determination of the natural history and malignant potential of IPMNs in MAS is needed.

Spontaneously Resolving Hyperreninemic Hypertension Caused by Accessory Renal Artery Stenosis in a 13-Year-Old Girl: A Case Report.

The authors describe the clinical investigation and progress of a 13-year-old girl diagnosed with hypertension 4 years prior to her admission. A thorough history was taken and physical examination performed. Laboratory analysis and relevant radiological evaluation were obtained in order to determine the etiology for suspected secondary hypertension, and later to differentiate between the possible causes of hyperreninemic hypertension. The patient had an accessory left renal artery, presumptively leading to renin secretion by the underperfused kidney. The patient was treated medically with spontaneous resolution of her hypertension and near normalization of plasma renin activity. On repeat imaging, the artery was not demonstrated. The authors concluded that the diagnosis of hyperreninemic hypertension in young ages should prompt investigation for the etiology. However, cautious observation is a valid option that might lead to spontaneous resolution.

Multimodality Image-Guided Cryoablation for Inoperable Tumor-Induced Osteomalacia.

Tumor-induced osteomalacia (TIO) is a debilitating paraneoplastic condition caused by small phosphaturic mesenchymal tumors (PMTs) that secrete large amounts of the phosphate-regulating and vitamin D-regulating hormone, FGF23. Tumor removal results in cure. However, because of high perioperative comorbidity, either from tumor location or host factors, surgery is sometimes not an option. Tumor destruction via cryoablation may be an effective option for inoperable PMTs. Three subjects with a confirmed diagnosis of TIO were studied. All three underwent cryoablation of suspected PMTs rather than surgery due to significant medical comorbidities or challenging anatomical location. Subject 3 had tumor embolization 24 hours prior to cryoablation because of the size and hypervascularity of the tumor. The success of the tumor cryoablation was defined by normalization of serum phosphate and FGF23. Cryoablation resulted in a rapid decrease in plasma intact FGF23 by 24 hours postprocedure in all three subjects (0, 2, and 9 pg/mL, respectively) with normalization of blood phosphate by postprocedure day 3. Three-day renal tubular reabsorption of phosphate increased to 76%, 94%, and 95.2%, respectively; 1, 25(OH)2 vitamin D increased to 84, 138, and 196 pg/ml, respectively. All three had dramatic clinical improvement in pain and weakness. Two subjects tolerated the procedure well with no complications; one had significant prolonged procedure-related localized pain. Although surgery remains the treatment of choice, cryoablation may be an effective, less invasive, and safe treatment for patients with difficult to remove tumors or who are poor surgical candidates. © 2017 American Society for Bone and Mineral Research.

Patients with McCune-Albright syndrome have a broad spectrum of abnormalities in the gastrointestinal tract and pancreas.

McCune-Albright Syndrome (MAS) is a rare sporadic syndrome caused by post-zygotic mutations in the GNAS oncogene, leading to constitutional mosaicism for these alterations. Somatic activating GNAS mutations also commonly occur in several gastrointestinal and pancreatic neoplasms, but the spectrum of abnormalities in these organs in patients with MAS has yet to be systematically described. We report comprehensive characterization of the upper gastrointestinal tract in seven patients with MAS and identify several different types of polyps, including gastric heterotopia/metaplasia (7/7), gastric hyperplastic polyps (5/7), fundic gland polyps (2/7), and a hamartomatous polyp (1/7). In addition, one patient had an unusual adenomatous lesion at the gastroesophageal junction with high-grade dysplasia. In the pancreas, all patients had endoscopic ultrasound findings suggestive of intraductal papillary mucinous neoplasm (IPMN), but only two patients met the criteria for surgical intervention. Both of these patients had IPMNs at resection, one with low-grade dysplasia and one with high-grade dysplasia. GNAS mutations were identified in the majority of lesions analyzed, including both IPMNs and the adenomatous lesion from the gastroesophageal junction. These studies suggest that there is a broad spectrum of abnormalities in the gastrointestinal tract and pancreas in patients with MAS and that patients with MAS should be evaluated for gastrointestinal pathology, some of which may warrant clinical intervention due to advanced dysplasia.

Postoperative fever discharge guidelines increase hospital charges associated with spine surgery.

BACKGROUND: Postoperative fever is a common sequel of spine surgery. In the presence of rigid nationally mandated clinical guidelines, fever management may consume more health care resources than is reasonably appropriate. OBJECTIVE: To study the relationship between postoperative fever, infection rate, and hospital charges in a cohort of spine surgery patients. METHODS: We retrospectively reviewed 578 spine surgery patients (lumbar microdiskectomy [LMD], anterior cervical decompression and fusion [ACDF], and lumbar decompression and fusion [LDF]). Differences in length of stay and hospital charges as well as risk factors and correlation with infection and readmission rates were studied. RESULTS: Postoperative fever occurred in 41.7% of all spine surgery patients and more often in LDF patients (77.2%). Type of surgery was the most important variable affecting the prevalence of postoperative fever. Significant differences in length of stay were elicited between patients with and without postoperative fever in the ACDF and LMD groups and in hospital cost in the LMD group. The average length of stay was 2.41 vs 4.47 (P < .01) in the LMD group, 1.67 vs 2.80 (P < .05) in the ACDF group, and 5.03 vs 5.65 (P > .05) in the LDF group. The average hospital charges were $16 261 vs $22 166 (P < .01) in the LMD group, $26 021 vs $29 125 (P > .05) in the ACDF group, and $53 627 vs $53 210 (P > .05) in the LDF group. Obesity, female sex, and ≥102°F postoperative temperature were the most significant predictors of infection. Delayed discharge referable to postoperative fever did not seem to influence the infection readmission rate. CONCLUSION: Postoperative fever in spine surgery patients is associated with a delay in patient discharge and increases in hospital charges. Postoperative fever discharge guidelines should be regularly and publicly subjected to appropriate cost-benefit analysis.