proteins

2026-09-29 | Tissue-nonspecific alkaline phosphatase deficiency is associated with altered immune cell profiles in hypophosphatasia.

Hypophosphatasia (HPP) is a rare metabolic disorder caused by mutations in the ALPL gene leading to tissue-nonspecific alkaline phosphatase (TNSALP) deficiency. Although traditionally considered a skeletal disease, emerging evidence suggests an immunomodulatory role for TNSALP in systemic inflammation and immune-mediated inflammatory diseases (IMIDs). This study investigated clinical, biochemical, and immunological features associated with inflammation in HPP. Forty-seven genetically confirmed HPP patients and 30 healthy controls with a comparable age and sex distribution were evaluated. Analyses included serum alkaline phosphatase (ALP), bone-specific ALP (BALP), C-reactive protein (CRP), fecal calprotectin (FCP), and flow cytometry in a subset of 29 HPP patients and 26 controls to assess leukocyte subpopulations and TNSALP expression, with confirmation by confocal microscopy. HPP patients exhibited reduced TNSALP expression in T cells, B cells, neutrophils, and monocytes, together with lower CD3 and CD8 fluorescence intensity and an increased CD16+/CD14+ monocyte ratio. IMIDs were frequent in this referral cohort and were associated with lower ALP and higher FCP. Within the flow-cytometry subset, lower proportions of CD8+ cells within the CD3-/CD19- NK-enriched population and of TNSALP+ B cells were associated with IMID status. These cross-sectional findings identify an association between TNSALP deficiency and a coordinated immune-inflammatory phenotype in HPP. They support the biological plausibility of an immunomodulatory role for TNSALP but do not establish that TNSALP deficiency causes inflammation or the development of IMIDs.

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2026-08-26 | Adult hypophosphatasia with a single heterozygous c.572A > G p.Glu191Gly mutation in the ALPL gene: Case report.

Adult-onset hypophosphatasia manifests after age 18, and is characterised by reduced tissue-nonspecific alkaline phosphatase activity. This can lead to fractures, pseudo-fractures, osteomalacia, decreased bone density (bone loss), muscle weakness, myalgia, arthralgia, headache, dental symptoms (loss of permanent teeth, periodontal disease), and pseudogout. Over 480 distinct genetic mutations have been identified to date, with eight cases reported for the c.572A > G (p.Glu191Gly) mutation. However, all reported cases involved compound heterozygous mutations, and there have been no previous reports of cases of a single heterozygous mutation. We report the case of a 40-year-old woman with persistent hypophosphatasia, elevated urinary phosphoethanolamine levels suggesting adult-onset hypophosphatasia, and a heterozygous missense mutation (c.572A > G p.Glu191Gly) in the ALPL gene according to genetic testing. Treatment with subcutaneous injections of aspartate phosphatase alpha was initiated, which was followed by significant improvement of the pain, enhanced range of motion in both upper limbs, and improved gait. This patient's case differed from previously reported cases in that it involved a heterozygous c.572A > G (p.Glu191Gly) mutation alone in adult-onset hypophosphatasia. Adult-onset hypophosphatasia is an extremely rare disorder. However, its symptoms resemble those of systemic rheumatic diseases such as polymyalgia rheumatica and fibromyalgia, and rheumatologists may encounter this condition in routine clinical practice. Importantly, it can be detected based on low serum ALP levels.

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2026-08-13 | Evolving Therapeutic Paradigms in Pediatric Hypophosphatasia: From Survival-Driven Care to Integrated Precision Management.

Hypophosphatasia (HPP) encompasses a group of inherited metabolic bone disorders characterized by defective skeletal mineralization and variable clinical severity in childhood. Substantial allelic heterogeneity contributes to a broad pediatric clinical spectrum, ranging from life-threatening perinatal disease to milder phenotypes characterized by chronic functional impairment. Historically, management relied primarily on supportive interventions aimed at sustaining survival, without modifying the underlying enzymatic defect. The introduction of enzyme replacement therapy (ERT) with asfotase alfa has fundamentally altered the natural history of pediatric HPP by supplementing deficient alkaline phosphatase activity at sites of active mineralization, thereby improving skeletal integrity, enhancing survival in severe forms, and supporting long-term functional gains. This therapeutic shift has redirected clinical priorities from survival alone toward sustained functional development and health-related quality of life. Nevertheless, variability in disease expression and therapeutic response persists, reflecting both diagnostic timing and the molecular heterogeneity of ALPL variants, whose phenotypic consequences cannot be predicted with complete certainty. Growing recognition of the importance of early diagnosis has prompted exploratory efforts toward systematic identification strategies, including neonatal screening initiatives reported in selected populations, which suggest the potential for earlier therapeutic intervention during active skeletal development. Together, these considerations highlight pediatric HPP as a model of precision-oriented management in rare metabolic bone disease, where timely diagnosis and targeted enzyme replacement must be aligned with long-term, multidisciplinary care to optimize outcomes.

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2026-08-12 | Enzyme replacement therapy with asfotase alfa in adult patients with hypophosphatasia

To study the efficacy of enzyme replacement therapy with asfotase alfa in adult patients with hypophosphatasia (HPP).

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2026-08-09 | Low ALP Screening Reveals High Prevalence of Mild Hypophosphatasia in Chinese Children

This dataset accompanies the research article titled “Low ALP Screening Reveals High Prevalence of Mild Hypophosphatasia in Chinese Children” (Manuscript No. jc.2026-01596). The aims of this study was to (1) establish a systematic, laboratory-based screening algorithm in a large-scale pediatric cohort to facilitate early identification of HPP and characterize ALPL variants through next-generation sequencing and in vitro functional validation; (2) delineate the clinical heterogeneity of HPP, with emphasis on milder phenotypes and previously underrecognized neurobehavioral presentations. The dataset consists of five files: “Zhang_jc.2026-01596_Supplemental fig1, Revised Supplemental table 1, Revised Supplemental table 2, Revised Supplemental table 3, Revised Supplemental table 4”. 1. Zhang_jc.2026-01596_Supplemental fig1: Distribution of primary reasons for initial hospital visit among children and adolescents with persistent low serum ALP, stratified by ALPL variant status. Reasons for visit were categorized into routine physical examination, pediatric surgical conditions, otorhinolaryngological disorders, neuropsychiatric conditions, growth-related concerns, and other miscellaneous conditions. The total cohort (n=339) (A) was divided into two subgroups: subjects without (n=225) (B) and subjects with ALPL gene variants (P/LP/VUS, n=114) (C). 2. Revised Supplemental table 1: Age- and sex-specific reference intervals for serum alkaline phosphatase in Chinese children. 3. Revised Supplemental table 2: Detailed ALPL variants and ACMG classifications identified in suspected HPP patients. 4. Revised Supplemental table 3: Detailed ALPL variants and ACMG classifications identified in heterozygous carriers. 5. Revised Supplemental table 4: Clinical, biochemical, and genetic characteristics of pediatric patients with suspected hypophosphatasia. This study was approved by the Ethics Committee of the Children’s Hospital of Soochow University (No. 2023036) and was conducted in strict accordance with the Declaration of Helsinki. Written informed consent was obtained from the parents or legal guardians of all participants.

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small molecules

2026-03-07 | Deficiency of Tissue Nonspecific Alkaline Phosphatase Dysregulates Microglial Morphology and Function in a Mouse Model of Infantile Hypophosphatasia.

Tissue-nonspecific alkaline phosphatase (TNAP) has emerged as a crucial regulator of neuronal circuit formation and maintenance; however, the complexities of its sex- and cell type-specific roles within microglia remain largely unexplored. To address this critical knowledge gap, this study examined how TNAP deficiency differentially affects microglial morphology, function, and signaling in both male and female mice, and investigated its broader implications for neurodevelopment and disease susceptibility. Using Alpl+/+ (wild-type) and Alpl-/- (TNAP knockout) mice, we conducted behavioral assessments at postnatal Days 13-14 to evaluate early neurobehavioral outcomes. Microglia were subsequently isolated for molecular, metabolic, and morphological analyses. TNAP-deficient mice of both sexes exhibited profound physiological deficits, including stunted growth and significant sensorimotor impairments, confirming effective TNAP knockout and indicating that systemic TNAP loss affects multiple cell types beyond microglia. At the cellular level, TNAP loss induced notable morphological changes in microglia, characterized by enlarged cell soma and shortened processes, hallmarks of microglial activation. Molecular profiling revealed upregulation of neuroinflammatory and phagocytic markers, implicating TNAP as a modulator of the innate immune response. Furthermore, metabolic analyses uncovered a dramatic shift in tryptophan-kynurenine metabolism, with increased quinolinic acid production signifying a transition to a neurotoxic, pro-inflammatory state. Additionally, TNAP-deficient microglia displayed extensive dysregulation in purinergic signaling pathways, exemplified by increased expression of key purinergic receptors, and acquired a senescent phenotype evidenced by elevated canonical senescence gene expression. Given the influence of TNAP deficiency on multiple cell populations, some observed microglial phenotypes may result from altered intercellular signaling or indirect effects. To delineate cell-autonomous effects, siRNA-mediated TNAP knockdown was performed in primary microglia isolated from wild-type (WT) mice. TNAP depletion modulated inflammatory responses, suggesting an intrinsic role for TNAP in microglial regulation; however, these effects may not fully recapitulate the extent of deficiency observed in vivo. Overall, TNAP emerges as a key modulator of microglial structure and function, with its dysfunction potentially increasing susceptibility to neurodevelopmental and neurodegenerative disorders. This highlights the potential of TNAP as a therapeutic target for central nervous system health and disease.

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2025-11-25 | Nutritional and Biochemical Aspects of Vitamin B6: Implications for Epilepsy and Health"

Abstract: Food is necessary for humans to synthesize vitamin B6, which is a water-soluble essential vitamin that must be obtained through diet. PLP, an active form of vitamin B6 among the six interconvertible compounds, is primarily found in meat and fish. It is particularly well known for its role in the synthesis of neurotransmitters such as dopamine from L-DOPA, serotonin from 5-HTP, and GABA from glutamate. Vitamin B6 is essential for mental health, and pyridoxine is derived from plants. PLP is the only vitamin B6 that works as a cofactor and coenzyme in many neurological reactions; thus, its deficiency is associated with several neurological disorders. Seizures are a sign of newborn epilepsy in 10% to 15% of babies, typically brought on by cortical abnormalities, genetic flaws, or inborn metabolic mistakes. This review focuses on nutritional sources, biochemical properties, and the many forms of epilepsy caused by Vitamin B6 deficiency. ALDH7A1 deficiency, hyperprolinaemia type II, Pyridoxamine Phosphate Oxidase deficiency, PLP-Binding Protein disorder, hypophosphatasia, and glycosylphosphatidylinositol anchor synthesis defect are among the vitamin B6-dependent epilepsy conditions that can be treated with PLP or pyridoxine. Based on the effects of Vitamin B6, we conclude that after identifying epilepsy symptoms in neonates, administer pyridoxine right away if the patient does not respond to the antiepileptic medications. This review offers advice and raises awareness on Vitamin B6 among health care professionals and information seekers.

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2025-10-23 | Enpp1 inhibition: a promising oral therapy for later-onset hypophosphatasia

Hypophosphatasia (HPP) is a rare, inherited metabolic bone disorder characterized by deficient activity of tissue-nonspecific alkaline phosphatase (TNAP), an enzyme encoded by the ALPL gene. Loss-of-function mutations in ALPL lead to reduced TNAP activity, resulting in the accumulation of extracellular inorganic pyrophosphate (PPi), a potent inhibitor of hydroxyapatite crystal formation and skeletal mineralization. Clinically, this presents as a broad spectrum of dento-osseous complications, including premature tooth loss, rickets or osteomalacia, and calcific arthropathies...

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2025-10-06 | ENPP1 inhibition as a therapeutic approach for later-onset hypophosphatasia.

Hypophosphatasia (HPP) is caused by loss-of-function mutations in the human ALPL gene that encodes tissue-nonspecific alkaline phosphatase (TNAP), whose deficiency results in the accumulation of the calcification inhibitor inorganic pyrophosphate (PPi), resulting in skeletal and dental hypomineralization. Enzyme replacement with mineral-targeted TNAP (asfotase alfa) improves skeletal mineralization but the almost daily injections of this biologic can lead to injection site reactions and discontinuation of treatment. Since PPi is produced by the enzymatic action of ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) from adenosine triphosphate (ATP), we tested if ENPP1 could be a druggable target for the development of an alternative treatment for HPP, particularly for the non-lethal later-onset forms of HPP, where enzyme replacement is not currently approved. We orally administered 30 and 100 mg/kg/day of an ENPP1 inhibitor, REV102, to the AlplPrx1/- mouse model of late-onset HPP, for 105 days and confirmed target engagement, as plasma PPi concentrations were markedly reduced. X-ray, micro-CT, and bone morphometry indicated improvement in appendicular skeletal mineralization. This study suggests that the adult HPP phenotype could benefit from oral administration of ENPP1 inhibitors.

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2025-10-01 | SUN-707 A Rare Case of Hypophosphatasia Presenting with Hypercalciuria

Abstract Disclosure: B. Singh: None. A.P. Amblee: None. Hypophosphatasia (HPP) is a rare bone mineralization disease which can present from childhood to adulthood. In the United States, it affects approximately 500-600 individuals per year. HPP is caused by inactivating mutations in the ALPL gene leading to buildup of inorganic pyrophosphate and impaired bone mineralization. Although generalized body pain, skeletal deformities, and dental abnormalities are the most common presenting features, approximately 20% of adults with HPP can present with renal abnormalities. Within this subgroup, 14% can present with hypercalcemia, hyperphosphatemia, or hypercalciuria. This case report is unique as the only feature found in a patient diagnosed with HPP was isolated hypercalciuria. A 51 year old male with HIV and chronic vitamin D deficiency was referred management of vitamin D deficiency . He was on bictegravir, emtricitabine, and tenofovir alafenamide for 14 years. He had no history of dental problems. He had a previous fracture of the tibia and wrist from a traumatic fall in his late 20s. Labs showed vitamin D was 19.78 ng/ml (normal range 30-100 ng/ml) , corrected calcium 8.9 mg/dl (normal range 8.7-10.4 mg/dl), alkaline phosphatase (AP) 40 U/L (normal range 45-117 U/L), and PTH 72 pg/mL (normal range 18-80.1 pg/ml). Thyroid studies and testosterone levels were within normal range. DXA scan showed normal bone mineral and low FRAX score. Vitamin D3 dosing was increased from 2000 to 5000 units daily. A secondary workup showed normal serum and urine protein electrophoresis, intact PTH, and celiac panel. He had an elevated 24-hour urine calcium level of 451 mg/24 hr. Due to the hypercalciuria, he was started on low dose hydrochlorothiazide. Vitamin D level normalized in 3 months ( 33 ng/ml)and AP remained low (38 U/L). Genetic testing for hypophosphatasia showed he was heterozygous for pathogenic variant in ALPL resulting in amino acid substitution p.Ala176Thr. Since this patient did not have any history of fractures, calcium and vitamin D supplementation was recommended. The unique feature is that he only presented with hypercalciuria which can have a long term risk for osteoporosis, kidney stone and chronic kidney disease . Due to heterogeneity in the presentation and disease course, HPP can be missed or underdiagnosed. Nonskeletal findings may be the main presenting factor in some adults, such as hypercalciuria in this case. Although more studies are required to look at the prevalence of isolated hypercalciuria in adult HPP patients, renal calcium abnormalities can be found in one fifth of HPP cases. HPP has a significantly negative effect on quality of life and early diagnosis with multidisciplinary interventions can help improve patient outcomes long term. Presentation: Sunday, July 13, 2025

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gene therapies

2026-03-12 | Lentivirus-based HPSC therapy provides effective and long-term treatment in hypophosphatasia mouse model.

Hypophosphatasia (HPP) is a multi-system metabolic disorder characterized by skeletal hypomineralization and perinatal lethality in severe cases and rickets, muscle weakness, and premature tooth loss in milder forms. It is caused by loss-of-function mutations in the ALPL gene encoding the tissue-nonspecific isozyme of alkaline phosphatase (TNALP). Currently, enzyme replacement therapy with asfotase alfa (STRENSIQ) is the only treatment approved for the most severe forms of the disease. It enhances survival and improves bone mineralization, but it is burdensome for the patients who must undergo daily, or every other day, injections for the rest of their lives. Alternative cell therapies are under development to overcome TNALP deficiency. Here, we report the development of a lentiviral vector (LVV), RMP100-LVV, to stably express soluble TNALP in LVV-transduced hematopoietic stem and progenitor cells (HSPCs). We show engraftment and differentiation of human RMP100-LVV-modified HSPCs in humanized mice and that treatment with this cell therapy approach leads to a durable correction of plasma alkaline phosphatase activity, rescues skeletal manifestations, and prevents early mortality in a severe HPP mouse model. Our study provides critical insights into treating metabolic bone disorders with an autologous HSPC-based gene therapy and demonstrates that this approach is a potential one-time treatment for HPP.

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2025-03-07 | Broad Vitamin B6-Related Metabolic Disturbances in a Zebrafish Model of Hypophosphatasia (Alpl-Deficiency)

Hypophosphatasia (HPP) is a rare inborn error of metabolism caused by pathogenic var-iants in ALPL, coding for tissue non-specific alkaline phosphatase. HPP patients suffer from impaired bone mineralization and in severe cases from vitamin B6-responsive sei-zures. To study HPP we generated alpl-/- zebrafish line using CRISPR/Cas9 gene-editing technology. At 5 days post fertilization (dpf) no alpl mRNA and 89% lower total alkaline phosphatase activity was detected in alpl-/- compared to alpl+/+ embryos. The survival of alpl-/- zebrafish was strongly decreased. Alizarin red staining showed decreased bone mineralization in alpl-/- embryos. B6 vitamer analysis revealed depletion of pyridoxal and its degradation product 4-pyridoxic acid in alpl-/- embryos. Accumulation of d3-pyridoxal 5’-phosphate (d3-PLP) and reduced formation of d3-pyridoxal in alpl-/- embryos incu-bated with d3-PLP confirmed Alpl involvement in vitamin B6 metabolism. Locomotion analysis showed pyridoxine treatment-responsive spontaneous seizures in alpl-/- embryos. Metabolic profiling of alpl-/- larvae using direct-infusion high-resolution mass spectrome-try showed abnormalities in polyamine and neurotransmitter metabolism, suggesting dysfunction of vitamin B6-dependent enzymes. Accumulation of N-methylethanolaminium phosphate indicated abnormalities in phosphoethanolamine metabolism. Taken together, we generated first zebrafish model of HPP that shows multi-ple features of human disease and is suitable to study pathophysiology of HPP and to test novel treatments.

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2025-02-02 | Novel therapeutic options for hypophosphatasia

In this issue of the Journal, Amadeu de Oliveira et al1 present the results of preclinical dosing studies using a single, intramuscular injection of mineral-targeted tissue-nonspecific alkaline phosphatase (TNAP-D10) delivered by an AA serotype 8 vector. They used 2 murine knock-out models mimicking early-onset (Alpl-/- mouse) and late-onset (AlplPrx1/Prx1 mouse) hypophosphatasia (HPP). Gene therapy at a dose of at 4 × 1010 vg/b fully corrected both the skeletal imaging and the biochemical phenotype in the early-onset model, and at doses of 4 × 108 and 4 × 109 in the female late-onset model. Surprisingly, the male late-onset mice responded less than female littermates, with high D10 immunolocalization in the liver and a putative inflammatory response. Apart from this sex difference in the late-onset HPP model, some further caveats should attract our attention. First, available data regarding improvement in osteomalacia (excessive unmineralized osteoid) or growth plate disarray2 have to be amended to substantiate full phenotype correction; and second, some ectopic calcification—a critical safety signal—was observed at the highest treatment doses in both murine models.

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2025-01-28 | Dental manifestations of hypophosphatasia: translational and clinical advances.

Hypophosphatasia (HPP) is an inherited error in metabolism resulting from loss-of-function variants in the ALPL gene, which encodes tissue-nonspecific alkaline phosphatase (TNAP). TNAP plays a crucial role in biomineralization of bones and teeth, in part by reducing levels of inorganic pyrophosphate (PPi), an inhibitor of biomineralization. HPP onset in childhood contributes to rickets, including growth plate defects and impaired growth. In adulthood, osteomalacia from HPP contributes to increased fracture risk. HPP also affects oral health. The dentoalveolar complex, that is, the tooth and supporting connective tissues of the surrounding periodontia, include 4 unique hard tissues: enamel, dentin, cementum, and alveolar bone, and all can be affected by HPP. Premature tooth loss of fully rooted teeth is pathognomonic for HPP. Patients with HPP often have complex oral health issues that require multidisciplinary dental care, potentially involving general or pediatric dentists, periodontists, prosthodontists, and orthodontists. The scientific literature to date has relatively few reports on dental care of individuals with HPP. Animal models to study HPP included global Alpl knockout mice, Alpl mutation knock-in mice, and mice with tissue-specific conditional Alpl ablation, allowing for new studies on pathological mechanisms and treatment effects in dental and skeletal tissues. Enzyme replacement therapy (ERT) in the form of injected, recombinant mineralized tissue-targeted TNAP has been available for nearly a decade and changed the prognosis for those with HPP. However, effects of ERT on dental tissues remain poorly defined and limitations of the current ERT have prompted exploration of gene therapy approaches to treat HPP. Preclinical gene therapy studies are promising and may contribute to improved oral health in HPP.

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2025-01-12 | Preclinical evaluation of the efficacy and safety of adeno-associated virus 8-tissue-nonspecific alkaline phosphatase-D10 in Alpl-/- and AlplPrx1/Prx1 mouse models for the treatment of early and late-onset hypophosphatasia.

We previously documented successful resolution of skeletal and dental disease in the infantile and late-onset murine models of hypophosphatasia (HPP) with a single injection of an adeno-associated serotype 8 vector encoding mineral-targeted TNAP (AAV8-TNAP-D10). Here, we conducted dosing studies in both HPP mouse models. A single escalating dose from 4 × 108 up to 4 × 1010 (vg/b) was intramuscularly injected into 4-day-old Alpl-/- mice (an infantile HPP model) and a single dose from 4 × 106 up to 4 × 109 (vg/b) was administered to 8-wk-old AlplPrx1/Prx1 mice (a late-onset HPP model). Wild-type littermates were used as controls. Serum alkaline phosphatase activity was increased, and PPi levels were decreased in a dose-dependent manner in both the Alpl-/- and AlplPrx1/Prx1 models. Radiographic and μCT analysis of long bones of female and male Alpl-/- mice showed full correction of skeletal phenotype at 4 × 1010 vg/b. We observed full correction of the bone phenotype at 4 × 108 and 4 × 109 in female AlplPrx1/Prx1 mice, but bones remained hypomineralized with the 4 × 106 and 4 × 107 (vg/b) doses after 70 d of treatment. We observed skeletal improvements using the 4 × 109 (vg/b) dose, but the phenotype was not fully corrected in male AlplPrx1/Prx1. Immunohistochemistry using anti-TNAP and anti-D10 antibodies showed high immunolocalization in the femurs of female AlplPrx1/Prx1 mice, while D10 immunolocalization was high in the liver of male AlplPrx1/Prx1 mice at a dose of 4 × 109 (vg/b). This sex-dependent difference was not seen in the infantile HPP model. A serum proteome analysis showed enhanced inflammatory pathways in treated AlplPrx1/Prx1 males compared to treated female mice. We also found a few areas of ectopic calcification in soft organs at the highest tested dose of 4 × 1010 (vg/b) in Alpl-/- or 4 × 109 (vg/b) in the AlplPrx1/Prx1 model. This pre-clinical study will inform the design of clinical trials to develop gene therapy in early-onset and late-onset HPP patients.

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antibodies

2026-04-22 | Non-nutritional rickets: Approach to diagnosis and management

Non-nutritional rickets (NNR) or refractory rickets encompasses a heterogeneous group of inherited and acquired disorders characterized by defective bone mineralization independent of dietary vitamin D or calcium deficiency. This narrative review synthesizes current evidence on the pathophysiology, clinical presentation, biochemical and radiological diagnosis, and management of the principal NNR subtypes: X-linked hypophosphatemic rickets, autosomal dominant/recessive hypophosphatemic rickets, hereditary hypophosphatemic rickets with hypercalciuria, tumor-induced osteomalacia, vitamin D-dependent rickets types 1 and 2, and hypophosphatasia. The transformative role of burosumab (anti-fibroblast growth factor 23 monoclonal antibody) and asfotase alfa (enzyme replacement therapy) is highlighted alongside emerging molecular therapies. Diagnostic algorithm and comprehensive comparison tables are provided to guide clinicians in timely identification and individualized treatment, aiming to improve long-term musculoskeletal and quality-of-life outcomes in affected children.

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2024-08-11 | Inherited phosphate and pyrophosphate disorders: New insights and novel therapies changing the oral health landscape.

Mineral metabolism is critical for proper development of hard tissues of the skeleton and dentition. The dentoalveolar complex includes the following 4 mineralized tissues: enamel, dentin, cementum, and alveolar bone. Developmental processes of these tissues are affected by inherited disorders that disrupt phosphate and pyrophosphate homeostasis, although manifestations are distinct from those in the skeleton. The authors discuss original data from experiments and comparative analyses and review articles describing effects of inherited phosphate and pyrophosphate disorders on dental tissues. A particular emphasis is placed on how new therapeutic approaches for these conditions may affect oral health and dental treatments of affected patients. Disorders of phosphate and pyrophosphate metabolism can lead to reduced mineralization (hypomineralization) or inappropriate (ectopic) calcification of soft tissues. Disruptions in phosphate levels in X-linked hypophosphatemia and hyperphosphatemic familial tumoral calcinosis and disruptions in pyrophosphate levels in hypophosphatasia and generalized arterial calcification of infancy contribute to dental mineralization defects. Traditionally, there have been few options to ameliorate dental health problems arising from these conditions. New antibody and enzyme replacement therapies bring possibilities to improve oral health in affected patients. Research over the past 2 decades has exponentially expanded the understanding of mineral metabolism, and has led to novel treatments for mineralization disorders. Newly implemented and emerging therapeutic strategies affect the dentoalveolar complex and interact with aspects of oral health care that must be considered for dental treatment, clinical trial design, and coordination of multidisciplinary care teams.

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2024-08-02 | Monoclonal antibody anti-sclerostin for treatment of pelvic insufficiency fractures in adult hypophosphatasia: A case report.

Hypophosphatasia is a rare inherited metabolic disease leading to inhibition of bone and teeth mineralization that can be complicated by multiple insufficiency fractures. Treatment is currently limited to enzyme replacement therapy using bone-targeting recombinant human alkaline phosphatase, or asfotase alfa. Romosozumab is a monoclonal anti-sclerostin antibody originally indicated for the treatment of osteoporosis in postmenopausal women with high-risk of fracture. Recently its indication had been expanded to other metabolic bone disorders such as osteogenesis imperfecta. We report a unique case of a 67-yer-old female with hypophosphatasia complicated by multiple delayed-union and nonunion insufficiency fractures of the pelvis. After 12-month therapy with Romosozumab to address her osteoporosis, the patient healed her fractures and increased her bone mass density. Our case report shows interesting effects of Romozumab in an adult patient with hypophosphatasia. It not only helped increase bone density, but also help in the healing process of delayed-union and nonunion insufficiency fractures of the pelvis and prevented the occurrence of new fractures during the treatment period. To our knowledge, this is the first report describing the potential effect of Romosozumab on insufficiency fractures in patients with hypophosphatasia.

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2024-01-04 | Τhe story of sclerostin inhibition: the past, the present, and the future.

Sclerostin inhibits osteoblast activity by hampering activation of the canonical Wnt signaling pathway and simultaneously stimulates osteoclastogenesis through upregulation of the receptor activator of NFκB ligand (RANKL). Thus, antibodies against sclerostin (Scl-Abs), besides promoting bone formation, suppress bone resorption and dissociate bone formation from resorption. This dual action results in remarkable increases of bone mineral density which are of a greater magnitude compared to the other antiosteoporotic treatments and are accompanied by decreases of fracture risk at all skeletal sites. The anabolic effect subsides after the first few months of treatment and a predominantly antiresorptive effect remains after this period, limiting its use to 12 months. Furthermore, these effects are largely reversible upon discontinuation; therefore, subsequent treatment with antiresorptives is indicated to maintain or further increase the bone gains achieved. Romosozumab is currently the only Scl-Ab approved for the treatment of severe postmenopausal osteoporosis. Indications for use in other populations, such as males, premenopausal women, and patients with glucocorticoid-induced osteoporosis, are pending. Additionally, the efficacy of Scl-Abs in other bone diseases, such as osteogenesis imperfecta, hypophosphatasia, X-linked hypophosphatemia, and bone loss associated with malignancies, is under thorough investigation. Cardiovascular safety concerns currently exclude patients at high cardiovascular risk from this treatment.

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2023-07-08 | The structural pathology for hypophosphatasia caused by malfunctional tissue non-specific alkaline phosphatase

Abstract Hypophosphatasia (HPP) is a metabolic bone disease that manifests as developmental abnormalities in bone and dental tissues. HPP patients exhibit hypo-mineralization and osteopenia due to the deficiency or malfunction of tissue non-specific alkaline phosphatase (TNAP), which catalyzes the hydrolysis of phosphate-containing molecules outside the cells, promoting the deposition of hydroxyapatite in the extracellular matrix. Despite the identification of hundreds of pathogenic TNAP mutations, the detailed molecular pathology of HPP remains unclear. Here, to address this issue, we determine the crystal structures of human TNAP at near-atomic resolution and map the major pathogenic mutations onto the structure. Our study reveals an unexpected octameric architecture for TNAP, which is generated by the tetramerization of dimeric TNAPs, potentially stabilizing the TNAPs in the extracellular environments. Moreover, we use cryo-electron microscopy to demonstrate that the TNAP agonist antibody (JTALP001) forms a stable complex with TNAP by binding to the octameric interface. The administration of JTALP001 enhances osteoblast mineralization and promoted recombinant TNAP-rescued mineralization in TNAP knockout osteoblasts. Our findings elucidate the structural pathology of HPP and highlight the therapeutic potential of the TNAP agonist antibody for osteoblast-associated bone disorders.

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other

2026-05-15 | In-utero cell transplantation for hypophosphatasia with gene-edited hESC-derived MSCs in a murine model.

The perinatal severe form of hypophosphatasia (HPP), caused by a deficiency in tissue-nonspecific alkaline phosphatase (TNAP), which is involved in bone metabolism, is a disease that manifests during fetal development. However, no established treatment can be performed in utero, and invasive treatment must be continued for a lifetime immediately after birth due to irreversible thoracic hypoplasia. We have developed an ex vivo in-utero gene cell therapy as a new treatment that can intervene at the fetal stage. We transduced the hALPL-D10 gene into human embryonic stem cell-derived mesenchymal stem cells to generate cells that overexpress TNAP. We transplanted the cells into the fetuses of HPP mice without immunosuppression by total body irradiation. The primary strength of this methodology lies in the fact that all experiments were conducted using immunocompetent animals with human cells. Compared to the untreated group, the treated group showed an extended survival rate (p = 0.005). In addition, the treated group showed significant weight gain (day 0 [p = 0.024], day 7 [p < 0.001], and day 14 [p = 0.017]) and improvement in bone lesions. Ex vivo in-utero gene cell therapy may be a new option for treating patients with HPP during gestation.

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2025-10-01 | MON-749 Long-Term in Vivo Expression of Tissue Nonspecific Alkaline Phosphatase by Ex Vivo Gene Edited B Cells as a Potential Treatment of Hypophosphatasia

Abstract Disclosure: P. Pierog: Be Biopharma. M. Brophy: Be Biopharma. W. Wong: Be Biopharma. X. Zhang: Be Biopharma. L. Li: Be Biopharma. J. Hickey: Be Biopharma. A. Lundberg: Be Biopharma. W. Bainter: Be Biopharma. C. Bullock: Be Biopharma. S. Keegan: Be Biopharma. S. Bedard-Shurtleff: Be Biopharma. T. Mullen: Be Biopharma. J. Edelstein: Be Biopharma. S. Bhawsar: Be Biopharma. G. Adekanye: Be Biopharma. E. Liberzon: Be Biopharma. S. Singh: Be Biopharma. M. Musial-Siwek: Be Biopharma. A. Hohmann: Be Biopharma. S. Arlauckas: Be Biopharma. A. Lazorchak: Be Biopharma. H. Liu: Be Biopharma. R. Morgan: Be Biopharma. Hypophosphatasia (HPP) is a rare metabolic disorder that causes skeletal abnormalities, chronic pain, and systemic complications. The condition arises from loss-of-function mutations in the ALPL gene that encodes the tissue-nonspecific alkaline phosphatase (TNSALP) enzyme. Deficient TNSALP activity leads to the accumulation of inorganic pyrophosphate (PPi), an inhibitor of bone mineralization, and pyridoxal 5’-phosphate responsible for disease manifestation. To address limitations of current therapies, we have developed a B cell-based cell therapy, termed BE-102. BE-102 is manufactured from primary human B cells by isolating, activating, and precision engineering with CRISPR/Cas9 followed by AAV and homology directed repair mediated insertion of human ALPL gene into CCR5 locus. Engineered TNSALP-producing cells, have properties of long-lived plasma cells and are expected to reduce elevated levels of substrates PPi and PLP, that accumulate in patients with HPP. BE-102 cells were manufactured from six healthy donors and were characterized for viability (84.9 ± 3.5%), CD38+ expression (93.3 ± 4.3%), ALPL transgene integration (45.1 ± 7.2%) and TNSALP secretion rate (9.5 ± 10.2 ng/mL/hour). In vitro pharmacology results demonstrate that BE-102 secretes active TNSALP (409.7 ± 10.2 µUnits/mL), which is capable of rescuing calcium deposition inhibited by PPi in a cell-based in vitro test system. Having demonstrated the in vitro function of BE-102, in vivo studies (N=3) were conducted in immune-deficient NOG-hIL6 mice. The animals received a single intravenous (IV) injection of 2 x107 viable cells. Human TNSALP was detected in serum at every time point starting at Day 1 and up to 6 months following a single dose of BE-102 using a human specific immunocapture assay. Consistent with BE-102 pharmacology, serum ALP activity showed statistically significant increase in BE-102 treated animals as compared to vehicle-treated animals. The in vivo data confirm long-term engraftment and continuous production of active TNSALP. Consistent with the expected pharmacology of BE-102 and construct design of ALPL transgene, human TNSALP activity was detected at day 90 in the bones of animals treated with BE-102 surrogate construct secreting TNSALP. These data confirm the delivery of functional TNSALP secreted by the surrogate construct to the bone, one of the main HPP disease target organs. Finally, clinical chemistry and hematology results from the end of the studies were all within acceptable ranges. Safety data together with the absence of adverse clinical observations and no unscheduled animal deaths support that BE-102 was well-tolerated in vivo. In summary, pharmacology and safety data establish non-clinical proof of concept that BE-102, has the potential to be a disease-modifying therapy by providing sustained level of active TNSALP following a single IV infusion for patients with HPP. Presentation: Monday, July 14, 2025

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2025-10-01 | OR36-08 Long-Term in Vivo Expression of Tissue Nonspecific Alkaline Phosphatase by Ex Vivo Gene Edited B Cells as a Potential Treatment of Hypophosphatasia

Abstract Disclosure: P. Pierog: None. M. Brophy: None. W. Wong: None. X. Zhang: None. L. Li: None. J. Hickey: None. A. Lundberg: None. W. Bainter: None. C. Bullock: None. S. Keegan: None. S. Bedard-Shurtleff: None. T. Mullen: None. J. Edelstein: None. S. Bhawsar: None. G. Adekanye: None. E. Liberzon: None. S. Singh: None. M. Musial-Siwek: None. A. Hohmann: None. S. Arlauckas: None. A. Lazorchak: None. H. Liu: None. R. Morgan: None. Hypophosphatasia (HPP) is a rare metabolic disorder that causes skeletal abnormalities, chronic pain, and systemic complications. The condition arises from loss-of-function mutations in the ALPL gene that encodes the tissue-nonspecific alkaline phosphatase (TNSALP) enzyme. Deficient TNSALP activity leads to the accumulation of inorganic pyrophosphate (PPi), an inhibitor of bone mineralization, and pyridoxal 5’-phosphate responsible for disease manifestation. To address limitations of current therapies, we have developed a B cell-based cell therapy, termed BE-102. BE-102 is manufactured from primary human B cells by isolating, activating, and precision engineering with CRISPR/Cas9 followed by AAV and homology directed repair mediated insertion of human ALPL gene into CCR5 locus. Engineered TNSALP-producing cells, have properties of long-lived plasma cells and are expected to reduce elevated levels of substrates PPi and PLP, that accumulate in patients with HPP. BE-102 cells were manufactured from six healthy donors and were characterized for viability (84.9 ± 3.5%), CD38+ expression (93.3 ± 4.3%), ALPL transgene integration (45.1 ± 7.2%) and TNSALP secretion rate (9.5 ± 10.2 ng/mL/hour). In vitro pharmacology results demonstrate that BE-102 secretes active TNSALP (409.7 ± 10.2 µUnits/mL), which is capable of rescuing calcium deposition inhibited by PPi in a cell-based in vitro test system. Having demonstrated the in vitro function of BE-102, in vivo studies (N=3) were conducted in immune-deficient NOG-hIL6 mice. The animals received a single intravenous (IV) injection of 2 x107 viable cells. Human TNSALP was detected in serum at every time point starting at Day 1 and up to 6 months following a single dose of BE-102 using a human specific immunocapture assay. Consistent with BE-102 pharmacology, serum ALP activity showed statistically significant increase in BE-102 treated animals as compared to vehicle-treated animals. The in vivo data confirm long-term engraftment and continuous production of active TNSALP. Consistent with the expected pharmacology of BE-102 and construct design of ALPL transgene, human TNSALP activity was detected at day 90 in the bones of animals treated with BE-102 surrogate construct secreting TNSALP. These data confirm the delivery of functional TNSALP secreted by the surrogate construct to the bone, one of the main HPP disease target organs. Finally, clinical chemistry and hematology results from the end of the studies were all within acceptable ranges. Safety data together with the absence of adverse clinical observations and no unscheduled animal deaths support that BE-102 was well-tolerated in vivo. In summary, pharmacology and safety data establish non-clinical proof of concept that BE-102, has the potential to be a disease-modifying therapy by providing sustained level of active TNSALP following a single IV infusion for patients with HPP. Presentation: Monday, July 14, 2025

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2022-10-25 | Generation of new human iPSC cell line (UOMi008-A) from a Hypophosphatasia patient.

A new induced pluripotent stem cell (iPSC) line namely UOMi008-A was generated from a patient having a childhood onset of Hypophosphatasia (HPP). This patient has compound heterozygous mutations c.571G > A (p.Glu191Lys) and c.1001G > A (p.Gly334Asp) in the ALPL gene respectively. This iPSC line will be used for in vitro disease modeling, which will aid in delineating the underlying molecular mechanism involved in disease pathogenesis and provide plausible new therapeutic directions.

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2021-10-25 | Bone-Specific Drug Delivery for Osteoporosis and Rare Skeletal Disorders.

The skeletal system provides an important role to support body structure and protect organs. The complexity of its architecture and components makes it challenging to deliver the right amount of the drug into bone regions, particularly avascular cartilage lesions. In this review, we describe the recent advance of bone-targeting methods using bisphosphonates, polymeric oligopeptides, and nanoparticles on osteoporosis and rare skeletal diseases. Hydroxyapatite (HA), a calcium phosphate with the formula Ca10(PO4)6(OH)2, is a primary matrix of bone mineral that includes a high concentration of positively charged calcium ion and is found only in the bone. This unique feature makes HA a general targeting moiety to the entire skeletal system. We have applied bone-targeting strategy using acidic amino acid oligopeptides into lysosomal enzymes, demonstrating the effects of bone-targeting enzyme replacement therapy and gene therapy on bone and cartilage lesions in inherited skeletal disorders. Virus or no-virus gene therapy using techniques of engineered capsid or nanomedicine has been studied preclinically for skeletal diseases. Efficient drug delivery into bone lesions remains an unmet challenge in clinical practice. Bone-targeting therapies based on gene transfer can be potential as new candidates for skeletal diseases.

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