Patent Publication Number: US-2021162023-A1

Title: Methods of treating neurofibromatosis type 1 and related conditions with alkaline phosphatase

Description:
BACKGROUND 
     Numerous diseases and conditions involve abnormal skeletal function, structure, or growth of bone or cartilage. An example of such a disease is neurofibromatosis type 1 (NF1 or Von Recklinghausen disease). NF1 is an autosomal dominant genetic disorder having an incidence of approximately 1 in 3,500 live births. The gene NF1 encodes neurofibromin, a member of the GTPase Activating Protein (GAP) family known to suppress the Ras kinase. Neurofibromin is a specific suppressor of p21-RAS, and mutations in the NF1 gene cause unsuppressed activation of RAS that lead to abnormal cell growth and differentiation. Common clinical features of NF1 include various oncogenic transformations, such as neurocutaneous neurofibromas and optic pathway tumors, and other non-cancer manifestations, such as cognitive defects and skeletal abnormalities. 
     Neurofibromatosis type 1 can interfere with the development of the spine. The disease may affect the protective covering of the spine, called the dura. Increased pressure in the spinal fluid due to neurofibromas of the spinal nerves can result in dural ectasia, which is a ballooning out of a sac that contains the cerebrospinal fluid. This condition may result in pain in the back and limbs, bladder control problems, and numbness in severe cases. Neurofibromatosis may also cause tumors on and around the spinal cord. Even benign tumors in this area can cause pain and weakness in the most severe cases. Osteoporosis is common among neurofibromatosis type 1 sufferers, who generally have lower bone density by age than healthy individuals. 
     Children with neurofibromatosis type 1 may develop dystrophic scoliosis, non-dystrophic scoliosis, and/or kyphosis. Scoliosis, an irregular side curvature of the spine from left to right, and kyphosis, a rounded or forward angulated back, occur together or separately in about one in five people with neurofibromatosis type 1. Non-dystrophic scoliosis, even in children with neurofibromatosis, is quite similar to “typical” scoliosis known as adolescent idiopathic scoliosis. Dystrophic scoliosis, however, is a more severe form of scoliosis that occurs due to bony changes related to neurofibromas affecting the spine. It may be accompanied by abnormally thin ribs, weakened vertebral bones, and severe spinal curvature. 
     Dystrophic scoliosis is a rare, but serious, skeletal manifestation in patients with NF1 that may be associated with debilitating neurological impairment (paraparesis, paraplegia). It is characterized by a sharp angulation involving several vertebrae, vertebral rotation, vertebral scalloping, vertebral wedging, and other radiographic features (Durrani et al., 2000). An anteroposterior spine radiograph, even in a patient only 14 years old, diagnosed with NF1, shows a thoracolumbar dystrophic scoliosis with a 49 degree curve over only 3 vertebrae (Petryk et al., 2016). 
     Dystrophic curves portend rapid progression and require early fusion, which is associated with significant morbidity. The postsurgical course is complicated by inherently poor bone healing in NF1 patients, resulting in pseudoarthrosis (lack of fusion) in as many as 60-100% of patients with NF-1 receiving posterior spinal fusion (Delucia et al., 2011). For example, 3 out of 3 NF1 patients with scoliosis who were treated had pseudoarthrosis after posterior spinal fusion, compared to 1/100 patients with adolescent idiopathic scoliosis. 
     Treatment for scoliosis is always challenging, but particularly so when dystrophic scoliosis is present. While physical therapy may be able to relieve minor structural problems with the spine, definitive treatment often requires orthopedic surgery. For example, arthrodesis, a method for inducing the ossification of bones by surgery, can be employed to effect a spinal fusion in affected patients. Arthrodesis can involve the use of a natural bone graft (e.g., an autograft or an allograft), or the introduction of a synthetic bone substitute into the affected area. Examples of synthetic bone substitutes include hydroxyapatite- or tricalcium phosphate-based granules, as well as bone morphogenetic proteins (BMP). Another option is the attachment of metal implants to the bones to hold them together in a position which favors bone growth. Arthrodesis is commonly used to promote healing of bone fractures in or near a joint in the spine, hand, ankle, foot, hip, or knee, for example, wherein the fractures are caused by accident, injury, or progressive deterioration. Arthrodesis can also be employed to treat NF1-associated scoliosis and kyphosis. The end result is typically the fusion of two adjoining bones such that movement of the bones relative to each other is restricted. 
     Based on animal and in vitro studies, poor bone healing in NF1 is thought to be due to a combination of reduced bone formation, increased bone resorption, and poor bone mineralization, the key processes involved in normal bone homeostasis and bone repair. Preclinical studies show that bone pathology in NF1 is, to a large degree, due to hyperactivation of Ras pathway and pyrophosphate (PPi) accumulation (de la Croix Ndong et al., 2014). Neurofibromin accelerates the conversion of the active Ras, bound to GTP into its inactive form, bound to GDP. It also leads to upregulation of expression of genes that promote PPi synthesis and extracellular transport, leading to PPi accumulation and inhibition of mineralization. Loss of NF1 also leads to impaired osteoblast differentiation from mesenchymal progenitor cells and alkaline phosphatase expression (Wu et al., 2006; Yu et al., 2005) as well as markedly increased osteoclastogenesis and bone resorption (Yang et al., 2006). 
     Given the difficulties with achieving solid arthrodesis after surgery for dystrophic scoliosis in NF1, single agent therapy was apparently not an appropriate or effective treatment strategy. The use of recombinant bone morphogenetic proteins (BMPs) to induce bone formation has been established in spinal fusion surgery, although the response of osteoprogenitor cells to BMP treatment alone in NF1 appears to be limited (de la Croix Ndong et al., 2014; Heerva et al., 2012), making the clinical outcome in this patient population unsatisfactory. 
     Subsequent studies have shown that a combined use of BMPs and bisphosphonates appears superior to BMP therapy alone in NF1-deficient mice (Schindeler et al., 2008) and NF1 patients (Birke et al., 2010) with pseudoarthrosis of the tibia. In a preclinical model of posterior spinal fusion, NF1-deficient mice treated with rhBMP2 and zoledronic acid also showed a significant improvement in fusion, although NF1-deficient mice still generated less bone than wild type controls (Bobyn et al., 2014). Other studies have combined these agents (Petryk et al., 2016). 
     However, the treatments that have been attempted so far, bone morphogenetic proteins (BMPs) to enhance bone formation and bisphosphonates (pamidronate and zoledronic acid) to inhibit bone resorption, failed to address the third key component of the pathogenic pathway in patients with NF1, which is impaired mineralization. Seitz et al. (2010) and surgical experience provide evidence for osteomalacia (reduced mineralization) in NF1 patients, presumably due to localized accumulation of PPi, and difficulty with surgical hardware remaining in its original location in the bone, with displacement of the rods into the surrounding soft tissue and even dura, resulting in serious neurological complications (Seitz et al., 2010). 
     Many skeletal diseases, including NF1, arise from loss of function of one or more proteins. As noted above, NF1 is characterized by the loss of neurofibromin. Another skeletal disease example is hypophosphatasia (HPP), a rare, heritable disease caused by one or more loss-of-function mutations in the gene ALPL, which encodes tissue-nonspecific alkaline phosphatase (TNALP or liver/bone/kidney type ALP). Alkaline phosphatase deficiency in osteoblasts and chondrocytes impairs skeletal mineralization, leading to symptoms of varying severity, from rickets or osteomalacia to almost complete absence of bone mineralization in utero. However, enzyme replacement therapy with unmodified alkaline phosphatase (e.g., infusion of native alkaline phosphatase) has been largely unsuccessful. Yet another example is achondroplasia, which causes dwarfism and may be accompanied by spinal complications such as kyphosis. 
     Improved treatments for neurofibromatosis, including NF1-related bone conditions, as well as for other forms of scoliosis, dystrophic scoliosis, kyphosis, fractures, demineralization, and the like, are needed. 
     SUMMARY 
     In general, this disclosure relates to the treatment of various diseases and conditions, including neurofibromatosis type 1, particularly dystrophic scoliosis and bone fractures, by administration of a soluble alkaline phosphatase (sALP, e.g., a sALP having at least 80, 85%, 90%, 95%, 97%, 99%, or 100% sequence identity to SEQ ID NO: 1, e.g., asfotase alfa), optionally in combination with a physical intervention, such as surgical intervention. In one embodiment, a disclosed method can result in stability following treatment, e.g., solid arthrodesis, stability of hardware inserted during the treatment method, increased stability of hardware present in the patient before the treatment method, and stable scoliosis (e.g., no increased curvature). 
     Provided herein is a method of treating at least one symptom of neurofibromatosis type 1 (NF1) in a patient. In one embodiment, the method includes at least one surgical intervention in a patient with NF1, and administering a sALP (e.g., a sALP having at least 80, 85%, 90%, 95%, 97%, 99%, or 100% sequence identity to SEQ ID NO: 1, e.g., asfotase alfa) to the patient before, during, and/or after the surgical intervention, at a dosage providing from about 0.2 mg/kg/week to about 12 mg/kg/week (e.g., from about 6 mg/kg/week to about 9 mg/kg/week, such as about 6 mg/kg/week, about 7 mg/kg/week, about 8 mg/kg/week, or about 9 mg/kg/week) of the sALP. In one embodiment, the sALP includes an amino acid sequence having at least 80, 85%, 90%, 95%, 97%, 99%, or 100% sequence identity to the sequence of SEQ ID NO: 1; preferably the sALP has the sequence of SEQ ID NO: 1. In one embodiment, the administration of the sALP results in one or more of (i) an increase in bone healing to result in new bone at a reference point in the patient compared to the reference point in the patient before the treatment, and/or (ii) an average change in bone mineral density of a reference point that is undetectable or no greater than 0.01% eight months after the administration of the sALP compared to the bone mineral density of the reference point in the patient before the treatment. In one embodiment, the at least one symptom includes one or more of spine curvature, kyphosis, osteoporosis, a weakened vertebra, thinning of a rib, rotation of a vertebra, vertebral wedging, erosion of a vertebra. rotational or angular spinal deformity, dural ectasia, incomplete bone mineralization, elevated blood and/or urine levels of phosphoethanolamine (PEA), hypomineralization, hypercalciuria, short stature, skeletal deformity, waddling gait, bone pain, bone fracture, weakness, and calcium pyrophosphate dihydrate crystal deposition. 
     Also provided herein is a method of treating at least one symptom of dystrophic scoliosis in a patient. In one embodiment, the method includes at least one surgical intervention on a patient with dystrophic scoliosis, and administering a sALP (e.g., a sALP having at least 80, 85%, 90%, 95%, 97%, 99%, or 100% sequence identity to SEQ ID NO: 1, e.g., asfotase alfa) to the patient before, during, and/or after the surgical intervention, at a dosage providing from about 0.2 mg/kg/week to about 12 mg/kg/week (e.g., from about 6 mg/kg/week to about 9 mg/kg/week, such as about 6 mg/kg/week, about 7 mg/kg/week, about 8 mg/kg/week, or about 9 mg/kg/week) of the sALP. In one embodiment, the sALP includes an amino acid sequence having at least 80, 85%, 90%, 95%, 97%, 99%, or 100% sequence identity to the sequence of SEQ ID NO: 1; preferably the sALP has the sequence of SEQ ID NO: 1. In one embodiment, the administration of the sALP results in one or more of (i) an increase in bone healing to result in new bone at a reference point in the patient compared to the reference point in the patient before the treatment, and/or (ii) an average change in bone mineral density of a reference point that is undetectable or no greater than 0.01% eight months after the administration of the sALP compared to the bone mineral density of the reference point in the patient before the treatment. In one embodiment, at least one symptom includes one or more of shorter and/or more sharply angulated curves compared to non-dystrophic scoliosis, bone abnormalities, thinning of a rib, a weakened vertebra bone, rotation of a vertebra, vertebral wedging, and erosion of a vertebra. In one embodiment, the dystrophic scoliosis includes NF1-related dystrophic scoliosis. 
     Further provided herein is a method of inducing bone healing in a patient. In one embodiment, the method includes administering a sALP to the patient at a dosage providing about 6 mg/kg/week of the sALP. In one embodiment, the method includes administering a sALP to the patient at a dosage providing about 9 mg/kg/week of the sALP. Alternatively, the method includes administering a dosage providing from about 0.2 mg/kg/week to about 12 mg/kg/week (e.g., from about 6 mg/kg/week to about 9 mg/kg/week, such as about 6 mg/kg/week, about 7 mg/kg/week, about 8 mg/kg/week, or about 9 mg/kg/week) of the sALP. In one embodiment, the sALP includes an amino acid sequence having at least 80, 85%, 90%, 95%, 97%, 99%, or 100% sequence identity to the sequence of SEQ ID NO: 1; preferably the sALP has the sequence of SEQ ID NO: 1. In one embodiment, the administration of the sALP is in conjunction with a surgical intervention. In one embodiment, the administration of the sALP results in one or more of (i) an increase in bone healing to result in new bone at a reference point in the patient compared to the reference point in the patient before the treatment, and/or (ii) an average change in bone mineral density of a reference point that is undetectable or no greater than 0.01% eight months after the administration of the sALP compared to the bone mineral density of the reference point in the patient before the treatment. 
     Further provided herein is method of treating at least one bone related disorder in a patient. The patient may be one that does not have a bone mineralization disorder (e.g., HPP, NF1, or craniosynostosis). In one embodiment, the method includes at least one surgical intervention in the patient. The method may include administering a sALP to the patient before, during, and/or after the surgical intervention, e.g., at a dosage providing from about 0.2 mg/kg/week to about 12 mg/kg/week (e.g., from about 6 mg/kg/week to about 9 mg/kg/week, such as about 6 mg/kg/week, about 7 mg/kg/week, about 8 mg/kg/week, or about 9 mg/kg/week). Administration of the sALP may result in one or more of an increase in bone healing that results in new bone at a reference point in the patient compared to the reference point in the patient before the treatment. In some embodiments, the patient has an average change in bone mineral density of a reference point that is undetectable or no greater than 0.01% eight months after the administration of the sALP compared to the bone mineral density of the reference point in the patient before the treatment. In other embodiments, the patient has an average change in bone mineral density of a reference point that is at least 0.01% eight months after the administration of the sALP compared to the bone mineral density of the reference point in the patient before the treatment. The at least one surgical intervention may be selected from the group consisting of arthroscopy of the knee, shoulder, hip, ankle, elbow, or wrist, fracture and meniscectomy, shoulder arthroscopy and decompression, carpal tunnel release, knee arthroscopy and chondroplasty, removal of support implant, knee arthroscopy and anterior cruciate ligament reconstruction, knee replacement, repair of femoral neck fracture, repair of trochanteric fracture, debridement of skin/muscle/bone/fracture, knee arthroscopy repair of one or both menisci, hip replacement, shoulder arthroscopy/distal clavicle excision, repair of rotator cuff tendon, repair fracture of radius or ulna, laminectomy, repair of ankle fracture (bimalleolar type), shoulder arthroscopy and debridement, lumbar spinal fusion, repair fracture of the distal part of radius, low back intervertebral disc surgery, incise finger tendon sheath, repair of ankle fracture (fibula), repair of femoral shaft fracture, and repair of trochanteric fracture. The hardware may be one or more of a screw, rod, plate, metal cage, nail, pin, and nut. 
     In one embodiment, the increase in bone healing is between two bones joined by arthrodesis, and in another embodiment the increase in bone healing is between two portions of a bone that has been separated by a fracture. In one embodiment, the increase in bone healing is in bone surrounding instrumentation. In one embodiment, the increase in bone healing is an increase in opacity. In one embodiment, the increase in opacity is determined by radiography or computed tomography (CT). 
     In one embodiment, the surgical intervention includes one or more of arthrodesis, removal of bone, insertion of bone graft material, or insertion of instrumentation. In one embodiment, the instrumentation includes one or more of screws, rods, plates, and metal cages. In one embodiment, the surgical intervention includes one or more of an open surgery or a minimally invasive surgery. In one embodiment, the sALP is administered about seven months after the surgical intervention (e.g., about seven to about twelve or more months after the surgical intervention). 
     The method can further include administering to the patient one or more bone morphogenetic protein(s) (BMP). In one embodiment, the BMP is administered during the surgical intervention. 
     The method can further include administering to the patient one or more bisphosphonate(s). In one embodiment, the bisphosphonate is administered after the surgical intervention. In one embodiment, the bisphosphonate is administered about three months after the surgical intervention (e.g., about three to about twelve months after the surgical intervention). 
     In one embodiment, the patient is about 12 years of age, or older than about 12 years of age. In one embodiment, the patient is about 18 years of age, or older than about 18 years of age. In one embodiment, the patient has not been previously administered the sALP. 
     In one embodiment, the sALP is formulated for daily or weekly administration. For instance, the sALP can be formulated for administration twice a week, three times a week, four times a week, five times a week, six times a week, or seven times a week. In one embodiment, the sALP is formulated at a dosage of 2 mg/kg for administration three times a week, at a dosage of 3 mg/kg for administration three times a week, or at a dosage of 1 mg/kg for administration six times a week. In one embodiment, the sALP is formulated for administration once daily, and in another embodiment is formulated for administration on consecutive or alternating days. In one embodiment, the sALP is administered for a treatment period of at least one month, at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, or longer. 
     In one embodiment, the sALP includes the amino acid sequence of SEQ ID NO: 1, and in another embodiment consists of the amino acid sequence of SEQ ID NO: 1. In one embodiment, the sALP is the soluble extracellular domain of an alkaline phosphatase. 
     In one embodiment, the sALP is administered in an amount that is therapeutically effective to treat at least one symptom of neurofibromatosis type 1, at least one symptom of dystrophic scoliosis, or to induce bone healing. 
     In one embodiment, the patient exhibits tolerability to administration of the sALP. The tolerability can include, for instance, a lack of or decreased incidence of adverse events selected from the group consisting of injection site erythema, decrease in hemoglobin, pyrexia, pneumonia, upper respiratory tract infection, otitis media, vomiting, constipation, diarrhea, tooth loss, nasopharyngitis, rash, dental carries, and irritability. 
     In one embodiment, the sALP is formulated in a pharmaceutical composition, with at least one pharmaceutically acceptable carrier. In one embodiment, the at least one pharmaceutically acceptable carrier is saline, and in another embodiment includes sodium chloride (e.g., 150 mM sodium chloride) and sodium phosphate (e.g., 25 mM sodium phosphate). In one embodiment, the pharmaceutical composition is formulated for subcutaneous, intramuscular, intravenous, oral, nasal, sublingual, intrathecal, or intradermal administration, or a combination thereof. 
     Also provided herein is a method that includes one or more of the features described herein. 
     By “asfotase alfa” is meant a human TNALP (hTNALP) fusion protein formulated for a method disclosed herein. Asfotase alfa (STRENSIQ®, Alexion Pharmaceuticals, Inc.) is a fusion protein including a soluble glycoprotein of two identical polypeptide chains, in which each polypeptide chain includes amino acid residues 1-726 of SEQ ID NO: 1 (see, for example, WO 2017/171871, and US Patent Application Publication 2013/0323244). The structure of each polypeptide chain includes the catalytic domain of hTNALP, the human immunoglobulin G1 Fc domain, and a deca-aspartate peptide used as a bone targeting domain (the structure hTNALP-Fc-D10). The two polypeptide chains are covalently linked by two disulfide bonds. Asfotase alfa has been approved under the trade name STRENSIQ® in many countries, including the United States, Europe, Japan, Canada, Israel, Australia, and Korea. 
     As used herein, “average” refers to a numerical value expressing the mean or median of a data set. The mean of a data set is calculated by dividing the sum of the values in the set by their number. The median of a date set is calculated by determining the middle value in a list of odd numbers or by determining the mean of the two data values in the middle in a list of even numbers. 
     The term “bone-targeting moiety,” as used herein, refers to an amino acid sequence of between 1 and 50 amino acid residues (such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 46, 48, or 50 amino acid residues) in length having a sufficient affinity to the bone matrix, such that the bone-targeting moiety, singularly, has an in vivo binding affinity to the bone matrix that is from about 10 −6  M to about 10 −15  M (e.g., 10 −7  M, 10 −8  M, 10 −9  M, 10 −10  M, 10 −11  M, 10 −12  M, 10 −13  M, 10 −1 4 M, or 10 −15  M). For example, the bone-targeting moiety can include a series of consecutive aspartate (D) and/or glutamate (E) residues, in which n=1 to 50, e.g., n=3-30, e.g., 5-15, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 36, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50. 
     The term “catalytically competent,” as used herein, refers to a sALP that hydrolyzes the bone mineralization inhibitor inorganic pyrophosphate (PPi) to provide inorganic phosphate (Pi), thereby decreasing the extracellular concentrations of PPi. Thus, the catalytically competent sALP improves skeletal mineralization in bone by regulating the concentration of PPi. 
     By “extracellular domain” is meant any functional extracellular portion of the native protein, e.g., alkaline phosphatase. In particular, the extracellular domain lacks the signal peptide. 
     By “Fc” is meant a fragment crystallizable region of an immunoglobulin, e.g., IgG-1, IgG-2, IgG-3, IgG-3 or IgG-4, including the CH2 and CH3 domains of the immunoglobulin heavy chain. Fc may also include any portion of the hinge region joining the Fab and Fc regions. The Fc can be of any mammal, including human, and may be post-translationally modified (e.g., by glycosylation). In a non-limiting example, Fc can be the fragment crystallizable region of human IgG-1 having the amino acid sequence of SEQ ID NO: 20. 
     By “fragment” is meant a portion of a polypeptide or nucleic acid molecule that contains, preferably, at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or more of the entire length of the reference nucleic acid molecule or polypeptide. A fragment may contain, e.g., 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 400, 500, 600, 700, or more amino acid residues, up to the entire length of the polypeptide. Exemplary sALP fragments have amino acid residues 18-498, 18-499, 18-500, 18-501, 18-502, 18-503, 18-504, 18-505, 18-506, 18-507, 18-508, 18-509, 18-510, 18-511, or 18-512 of an ALP (e.g., SEQ ID NOs: 2-6), and may include additional C-terminal and/or N-terminal portions. Biological activity of such fragments is tested in standard assays known in the art, e.g., by a non-compartmental analysis (NCA) to calculate pharmacokinetic parameters of a sALP fragment. 
     By “naïve patient” is meant a patient having at least one symptom of neurofibromatosis type 1, having at least one symptom of dystrophic scoliosis, or in need of bone healing that has never received treatment with a sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa). 
     The terms “peptide,” “polypeptide,” and “protein” are used interchangeably and refer to any chain of two or more natural or unnatural amino acid residues, regardless of post-translational modification (e.g., glycosylation or phosphorylation), constituting all or part of a naturally-occurring or non-naturally occurring polypeptide or peptide, as is described herein. 
     By “pharmaceutically acceptable carrier” or “pharmaceutically acceptable excipient” is meant at least one carrier or excipient, respectively, which is physiologically acceptable to the treated patient while retaining the therapeutic properties of the compound with which it is administered. One exemplary pharmaceutically acceptable carrier substance is physiological saline. For instance, the pharmaceutically acceptable carrier can include sodium chloride (e.g., 150 mM sodium chloride) and sodium phosphate (e.g., 25 mM sodium phosphate). Other physiologically acceptable carriers and their formulations are known to those skilled in the art and described, e.g., in Remington&#39;s Pharmaceutical Sciences (20th edition), A. Gennaro, Ed., 2000, Lippincott, Williams &amp; Wilkins, Philadelphia, Pa. 
     By “pharmaceutical composition” is meant a composition containing a polypeptide or nucleic acid molecule as described herein formulated with at least one pharmaceutically acceptable excipient, diluent, or carrier. The pharmaceutical composition may be manufactured or sold with the approval of a governmental regulatory agency as part of a therapeutic regimen for the treatment or prevention of a disease or event in a patient. Pharmaceutical compositions can be formulated, for example, for subcutaneous administration, intravenous administration (e.g., as a sterile solution free of particulate emboli and in a solvent system suitable for intravenous use), for oral administration (e.g., a tablet, capsule, caplet, gelcap, or syrup), or any other formulation described herein, e.g., in unit dosage form. 
     The term “physiologically active,” as used herein, refers to a sALP that hydrolyzes phosphoethanolamine (PEA), inorganic pyrophosphate (PPi), and pyridoxal 5′-phosphate (PLP) to provide Pi, thereby decreasing extracellular concentrations of PEA, PPi, and PLP. 
     The terms “sALP,” “soluble alkaline phosphatase,” and “extracellular domain of an alkaline phosphatase” are used interchangeably and refer to a soluble, non-membrane bound alkaline phosphatase (ALP) or a domain or a biologically active fragment of the soluble, non-membrane bound ALP. sALPs include, for example, an alkaline phosphatase lacking a C-terminal glycolipid anchor (GPI signal sequence, e.g., polypeptides including or consisting of the amino acid residues 18-502 of a human TNALP (SEQ ID NOs: 2, 3, 4, 5, or 6)). In particular, a TNALP may include, e.g., a polypeptide including or consisting of amino acid residues 1-485 of SEQ ID NO: 1, such as asfotase alfa, or a polypeptide variant having at least 95% sequence identity to the amino acid residues 1-485 of SEQ ID NO: 1. sALPs further include, for example, mammalian orthologs of human TNALP, such as a rhesus TNALP (SEQ ID NO: 7), a rat TNALP (SEQ ID NO: 8), a canine TNALP (SEQ ID NO: 9), a porcine TNALP (SEQ ID NO: 10), a murine TNALP (SEQ ID NO: 11), a bovine TNALP (SEQ ID NOs: 12-14), or a feline TNALP (SEQ ID NO: 15). sALPs also include soluble, non-membrane-bound forms of human PALP (e.g., polypeptides including or consisting of amino acid residues 18-502 of SEQ ID NOs: 16 or 17), GCALP (e.g., polypeptides including or consisting of amino acid residues 18-502 of SEQ ID NO: 18), and IALP (e.g., polypeptides including or consisting of amino acid residues 18-502 of SEQ ID NO: 19), and additional variants and analogs thereof that retain alkaline phosphatase activity, e.g., the ability to hydrolyze PPi. A sALP, in particular, lacks the N-terminal signal peptide (e.g., aa 1-17 of SEQ ID NOs: 2-6, 8, 11-13, or 15 or aa 1-25 of SEQ ID NO: 7). 
     By “sALP fusion polypeptide” is meant a polypeptide having the structure Z-sALP-Y-spacer-X-Wn-V, Z-Wn-X-spacer-Y-sALP-V, Z-sALP-Y-Wn-X-spacer-V, and Z-Wn-X-sALP-Y-spacer-V. In particular, the sALP fusion polypeptide can be Z-sALP-Y-spacer-X-Wn-V or Z-Wn-X-spacer-Y-sALP-V, such as hTNALP-Fc-D10 (e.g., asfotase alfa; the amino acid sequence SEQ ID NO: 1). Any one of X, Y, Z, V, the spacer, and/or Wn can be absent or an amino acid sequence of at least one amino acid. For example, X, Y, Z, and V may be a dipeptide sequence (e.g., leucine-lysine or aspartic acid-isoleucine), such as a two-residue linker at the Y position (e.g., leucine-lysine) and a two residue linker at the X position (e.g., aspartic acid-isoleucine). Spacers include, for example, a Fc region of an immunoglobulin, such as the amino acid sequence of SEQ ID NO: 20. Wn can be a bone-targeting moiety as defined herein, e.g., having a series of consecutive aspartate (D) or glutamate (E) residues, in which n=1 to 50, e.g., n=3-30, e.g., 5-15, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 36, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50. 
     By “signal peptide” is meant a short peptide (5-30 amino acids long) at the N-terminus of a polypeptide that directs a polypeptide towards the secretory pathway (e.g., the extracellular space). The signal peptide is typically cleaved during secretion of the polypeptide. The signal sequence may direct the polypeptide to an intracellular compartment or organelle, e.g., the Golgi apparatus. A signal sequence may be identified by homology, or biological activity, to a peptide with the known function of targeting a polypeptide to a particular region of the cell. One of ordinary skill in the art can identify a signal peptide by using readily available software (e.g., Sequence Analysis Software Package of the Genetics Computer Group, University of Wisconsin Biotechnology Center, 1710 University Avenue, Madison, Wis. 53705, BLAST, or PILEUP/PRETTYBOX programs). A signal peptide can be one that is, for example, substantially identical to amino acid residues 1-17 of SEQ ID NOs: 2-6 or amino acid residues 1-25 of SEQ ID NO: 7. 
     As used herein, when a polypeptide or nucleic acid sequence is referred to as having “at least X % sequence identity” to a reference sequence, wherein “X” is a real number, it is meant that at least X percent of the amino acid residues or nucleotides in the polypeptide or nucleic acid are identical to those of the reference sequence when the sequences are optimally aligned. An optimal alignment of sequences can be determined in various ways that are within the skill in the art, for instance, the Smith Waterman alignment algorithm (Smith et al.,  J. Mol. Biol.  147:195-7, 1981) and BLAST (Basic Local Alignment Search Tool; Altschul et al.,  J. Mol. Biol.  215: 403-10, 1990). These and other alignment algorithms are accessible using publicly available computer software such as “Best Fit” (Smith and Waterman,  Advances in Applied Mathematics,  482-489, 1981) as incorporated into GeneMatcher Plus (Schwarz and Dayhoff,  Atlas of Protein Sequence and Structure, Dayhoff , M. O., Ed pp 353-358, 1979), BLAST, BLAST-2, BLAST-P, BLAST-N, BLAST-X, WU-BLAST-2, ALIGN, ALIGN-2, CLUSTAL, Megalign (DNASTAR), or other software/hardware for alignment. In addition, those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve optimal alignment over the length of the sequences being compared. 
     The terms “patient” or “subject” refer to a mammal, including, but not limited to, a human or a non-human mammal, such as a bovine, equine, canine, ovine, or feline. 
     “Parenteral administration,” “administered parenterally,” and other grammatically equivalent phrases, as used herein, refer to modes of administration other than enteral and topical administration, usually by injection, and include, without limitation, subcutaneous, intradermal, intravenous, intranasal, intraocular, pulmonary, intramuscular, intra-arterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, intrapulmonary, intraperitoneal, transtracheal, subcuticular, intraarticular, subcapsular, subarachnoid, intraspinal, epidural, intracerebral, intracranial, intracarotid, and intrasternal injection and infusion. 
     By “therapeutically effective amount” is meant an amount of a polypeptide or nucleic acid molecule described herein that is sufficient to substantially improve, treat, prevent, delay, suppress, or arrest at least one symptom of neurofibromatosis type 1, at least one symptom of dystrophic scoliosis, or induce bone healing. A therapeutically effective amount of a composition described herein may depend on the severity of the disorder being treated and the condition, weight, and general state of the patient and can be determined by an ordinarily-skilled artisan with consideration of such factors. A therapeutically effective amount of a composition described herein can be administered to a patient in a single dose or in multiple doses administered over a period of time. 
     By “treating,” “treat,” or “treatment” is meant the medical management of a patient with the intent to cure, ameliorate, stabilize, reduce the likelihood of, or prevent at least one symptom of neurofibromatosis type 1, or at least one symptom of dystrophic scoliosis and/or management of a patient exhibiting or likely to have at least one symptom of neurofibromatosis type 1, or at least one symptom of dystrophic scoliosis, e.g., by administering a pharmaceutical composition. This term also means the medical management of a patient with the intent to cure, ameliorate, or stabilize a condition requiring bone healing and/or management of a patient exhibiting or likely to have a condition requiring bone healing, e.g., by administering a pharmaceutical composition. This term includes active treatment, that is, treatment directed specifically toward the improvement or associated with the cure of a disease, pathological condition, disorder, or event, and also includes causal treatment, that is, treatment directed toward removal of the cause of the associated disease, pathological condition, disorder, or event. In addition, this term includes palliative treatment, that is, treatment designed for the relief or improvement of at least one symptom rather than the curing of the disease, pathological condition, disorder, or event; symptomatic treatment, that is, treatment directed toward constitutional symptoms of the associated disease, pathological condition, disorder, or event; preventative treatment, that is, treatment directed to minimizing or partially or completely inhibiting the development of the associated disease, pathological condition, disorder, or event, e.g., in a patient who is not yet ill, but who is susceptible to, or otherwise at risk of, a particular disease, pathological condition, disorder, or event; and supportive treatment, that is, treatment employed to supplement another specific therapy directed toward the improvement of the associated disease, pathological condition, disorder, or event. 
     The words “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure. 
     The terms “comprises” and variations thereof do not have a limiting meaning where these terms appear in the description and claims. 
     Unless otherwise specified, “a,” “an,” “the,” and “at least one” are used interchangeably and mean one or more than one. 
     Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.8, 4, 5, etc.). 
     For any method disclosed herein that includes discrete steps, the steps may be conducted in any feasible order. And, as appropriate, any combination of two or more steps may be conducted simultaneously. 
     The above summary of the disclosure is not intended to describe each disclosed embodiment or every implementation of the disclosure. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance may be provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is aradiograph showing severe dystrophic lumbar scoliosis in a 47 year old patient. The arrow points to the marked left convex dystrophic scoliosis of thoracolumbar spine with apex at L3. This radiograph shows a dystrophic curve because of the short, sharp angles, dural ectasia, vertebral body scalloping, vertebral wedging, and narrowed pedicles. 
         FIG. 2  is a computed tomography (CT) scan of the lumbar spine of the same 47 year old patient identified in  FIG. 1 . The CT scan shows severe dural ectasia throughout the lumbar but most pronounced at L2 and L3, denoted by arrows, where there is prominent posterior vertebral body scalloping. 
         FIGS. 3A-3B  are CT scans performed 6 months before the fourth spinal surgery of the 47 year old patient.  FIG. 3A  shows peripheral lucency of the left posterior iliac spine screw, denoted by an arrow. 
         FIG. 3B  shows fracture of the left vertical connecting rod below the left L4 pedicle screw, denoted by an arrow. 
         FIG. 4  is a radiograph of a postoperative plain film showing spinal fusion instrumentation from T11 to sacrum with bilateral iliac screws and markedly improved dystrophic scoliosis deformity. 
         FIGS. 5A-5B  are postoperative CT scans performed 2 days after spinal surgery.  FIG. 5A  shows stable lucency around the left posterior iliac screw, denoted by an arrow.  FIG. 5B  shows fracture of outer cortex of the bone at the tip of the left posterior iliac screw, denoted by an arrow. 
         FIG. 6  is a CT scan performed 13 months after spinal surgery and following 6 months of treatment with asfotase alfa. The CT scan shows marginal lucency around the screw without evidence of loosening (upper arrow) and healed fracture at the tip of the left posterior iliac screw (lower arrow). 
     
    
    
     DETAILED DESCRIPTION 
     We have discovered several new and unexpected uses for asfotase alfa (SEQ ID NO: 1, STRENSIQ®, Alexion Pharmaceuticals, Inc.). Asfotase alfa, when combined with bone morphogenetic protein (BMP) and bisphosphonate therapy, resulted in solid arthrodesis after spinal surgery in a patient with NF1-related dystrophic scoliosis, where surgery combined with BMP therapy alone had previously failed. This result was unexpected because the patient was not deficient for tissue-nonspecific alkaline phosphatase, yet administration of the tissue-nonspecific alkaline phosphatase, asfotase alfa, resulted in solid arthrodesis. Thus, there was a synergistic effect when asfotase alfa was combined with surgical intervention, resulting in, for instance, improved postsurgical bone healing and/or mineralization. In one embodiment, asfotase alfa can be used to treat patients with one or more symptoms of neurofibromatosis type 1. In one embodiment, asfotase alpha can be used to treat patients with dystrophic scoliosis. In one embodiment, asfotase alfa can be used to promote bone healing. The use of asfotase alfa may occur in conjunction with a physical intervention, such as a surgical intervention. Optionally, the use of asfotase alfa occurs in conjunction with administration of one or more bone morphogenetic protein, one or more bisphosphonates, or a combination thereof. 
     Methods of Treatment 
     In some embodiments of the method, sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant described herein, such as a variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) is administered to a patient in an amount that is therapeutically effective to treat at least one symptom of neurofibromatosis type 1, e.g., spine curvature, kyphosis, osteoporosis, weakened vertebral bones, thinning of the ribs, rotation of the vertebrae, vertebral wedging, erosion of vertebrae. rotational or angular spinal deformity, dural ectasia, incomplete bone mineralization, elevated blood and/or urine levels of phosphoethanolamine (PEA), hypomineralization, hypercalciuria, short stature, skeletal deformity, waddling gait, bone pain, bone fracture, weakness, and calcium pyrophosphate dihydrate crystal deposition). 
     In some embodiments of the method, sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 80, 85%, 90%, 95%, 97%, 99%, or 100% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) is administered to a patient in an amount that is therapeutically effective to treat at least one symptom of dystrophic scoliosis, for example NF1-related dystrophic scoliosis, e.g., shorter and more sharply angulated curves than seen in non-dystrophic scoliosis, bone abnormalities including thinning of the ribs, weakened vertebral bones, significant rotation of the vertebrae, vertebral wedging, and erosion of the vertebrae by the spinal fluid. 
     In one embodiment of the method, sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 80, 85%, 90%, 95%, 97%, 99%, or 100% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) is administered to a patient in an amount that is therapeutically effective to induce bone healing. Examples of inducing bone healing includes treating a bone fracture and arthrodesis, the surgical fusion of two joints. For example, the method is useful to promote spinal fusion. Spinal fusion surgery can be used to eliminate bone-on-bone friction and/or to relive nerve compression that cause pain and other symptoms. Surgical bone fusion can also be used on fingers, ankles, and feet, for instance. 
     In some embodiments of the method, sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant described herein, such as a variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) is administered to a patient who has undergone an orthopedic surgery. The surgery may include at least one implant or hardware inserted during the surgery. The patient may be one that does not have neurofibromatosis type 1 (NF1), HPP, or craniosynostosis. The patient may have a disease or disorder, or may have one or more bone related conditions, such as spine curvature, kyphosis, osteoporosis, weakened vertebral bones, thinning of the ribs, rotation of the vertebrae, vertebral wedging, erosion of vertebrae. rotational or angular spinal deformity, dural ectasia, incomplete bone mineralization, elevated blood and/or urine levels of phosphoethanolamine (PEA), hypomineralization, hypercalciuria, short stature, skeletal deformity, waddling gait, bone pain, bone fracture, weakness, and calcium pyrophosphate dihydrate crystal deposition. In some embodiments, the patient has hardware inserted into bone that fails. The patient may have had one or more orthopedic surgeries (e.g., revision surgeries) in which implant fixation has failed. For example, the patient may have, or may be in need of, a craniofacial implant, dental implant, spinal implant, joint replacement part for hip, knee, shoulder, spine, elbow, or wrist, or a bone fixation material, such as a nail, screw, pin, nut, rod, and plate. The patient may also be in need of a revision surgery, in which a craniofacial implant, dental implant, spinal implant, joint replacement part for hip, knee, shoulder, spine, elbow, or wrist, or a bone fixation material, such as a nail, screw, pin, nut, rod, and plate, has failed. 
     Orthopedic surgeries that may include an implant or hardware include, for example, surgeries to the hand or upper extremity, shoulder, elbow, joint (e.g., total joint reconstruction, e.g., arthroplasty), foot, ankle, spine, musculoskeletal oncology related surgery, sports injury related surgery, trauma, and the like. Other common orthopedic surgeries that may include the use of hardware or an implant include, for example, arthroscopy of the knee, shoulder, hip, ankle, elbow, or wrist, fracture and meniscectomy, shoulder arthroscopy and decompression, carpal tunnel release, knee arthroscopy and chondroplasty, removal of support implant, knee arthroscopy and anterior cruciate ligament reconstruction, knee replacement, repair of femoral neck fracture, repair of trochanteric fracture, debridement of skin/muscle/bone/fracture, knee arthroscopy repair of one or both menisci, hip replacement, shoulder arthroscopy/distal clavicle excision, repair of rotator cuff tendon, repair fracture of radius (bone)/ulna, laminectomy, repair of ankle fracture (bimalleolar type), shoulder arthroscopy and debridement, lumbar spinal fusion, repair fracture of the distal part of radius, low back intervertebral disc surgery, incise finger tendon sheath, repair of ankle fracture (fibula), repair of femoral shaft fracture, and repair of trochanteric fracture. A patient who has undergone any of the foregoing orthopedic procedures may be treated with a sALP according to the methods described herein in order to improve the repair of the bone or to improve fixation of the implant or hardware. 
     The sALP may be used for repair of bone trauma or a bone defect that may have resulted from surgery or disease. The damaged or fragmented bone tissue may be reconstructed using an implant or hardware and supplemented by administration of a sALP before, during, or after a surgery to repair the defect. The implant or hardware, in combination with sALP administration, may further provide the necessary mechanical support for the remaining pieces of bone fragments at the site of damage and simultaneously allow blood and bone forming cells from adjacent tissues to penetrate the implant for improved healing. For example, the methods described herein can be used to repair calvarial bone defects after neurosurgical operations and traumas, in reconstructions of bony orbital floors and jaw bones. The methods described herein can also be used in orthopedics and spine surgery, as well as in fixation of fragmented pieces of bone and cosmetic surgeries. In the presence of long bones weakened by diseases, or when parts of the cortical bone are lost, the implant can be used to reinforce the long bones and cover openings where cortical bone is lost. 
     The methods described herein may also be used with bones of reduced quality (e.g., osteoporotic bone) or in revision surgeries (e.g., they can be used to replace previously inserted implants). The sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant described herein, such as a variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be used, for example, in osteosynthesis to internally stabilize and/or join bones, e.g., fractured (broken) bones, either in conjunction with mechanical stabilizing devices, such as metal plates, pins, rods, or wires, or individually. 
     The methods described herein may also be used to treat a bone defect in a patient with a fracture requiring compression. In particular, the sALP can be administered in conjunction with an implant that may be used to provide compressive fixation in a patient. 
     Bones that can be treated according to the methods described herein include, for example, subarticular fracture, a defect of the spine or vertebra, or a defect of the radius, ulna, fibula, clavicle, humerus, pelvis, femur, patella, tibia, talus, calcaneus, navicular, cuneiforms, metatarsals, metacarpals, phalanges, scapula, ankle, maxilla, or mandible. The implant or hardware can be positioned in proximity to the bone defect (e.g., positioning the implant so that it contacts the intraosseous space of a bone). The sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant described herein, such as a variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) may be administered at any time before, during, or after administration of the implant or hardware. The sALP may be coated on the implant or hardware. 
     Treatment methods of the invention also include maxillomandibular or craniofacial fixation, temporary fixation for repairing a bone defect in a staged reconstruction, glenoid or humeral fixation, patellar fixation, or spine fixation. For example, in spinal surgeries, the implant may be placed within a pedicle, used to anchor an interbody device, used to anchor spinal fusion plates and spacer replacement, used in an osteoporotic vertebra, or positioned in proximity to the spinous processes of adjacent vertebrae. The method may also include the insertion of a rod, pin, nail, or mesh or bone plate in proximity to the bone defect. The sALP may be administered at any time before, during, or after the surgery. The sALP may be coated on any implant or hardware. 
     Particular bone defects that may be treated using the methods described herein include, e.g., any bone deficient region, such as a void, gap, recess, or other discontinuity in a bone. The bone defect may be due to, for example, disease or trauma. The implants or hardware described herein can be applied, for example, in the repair of periodontal defects, in craniofacial or maxillofacial surgery or reconstruction, in cosmetic surgery, in hand surgery, in joint reconstruction, in fracture repair, in orthopedic surgical procedures, and in spinal fusion. The implants may also be used, for example, in osteosynthesis to internally stabilize and/or join bones, e.g., fractured (broken) bones, either in conjunction with other mechanical devices, such as washers (e.g., a washer of the invention), metal plates, pins, rods, or wires, or individually. For example, the implants can be used with a washer to provide compressive fixation of bone defects and bone fractures. In particular, the methods are useful for the treatment of defects or breaks in large bones. Non-limiting examples of bone fractures include, e.g., stable fractures, transverse fractures, oblique fractures, spiral fractures, comminuted fractures and open and displaced fractures. Exemplary large bones that may require fracture fixation include, e.g., the femur, tibia, fibula, humerus, ulna, radius, ribs, innominate bone (hip bone), and sternum. For each of these surgeries, the sALP may be administered at any time before, during, or after the surgery. 
     Surgical Intervention 
     Administration of sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1, or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) in any of the disclosed methods can occur in conjunction with a physical intervention, for instance, surgical intervention. Surgical intervention can be used for arthrodesis, removal of bone, insertion of bone graft material, or setting a fractured bone. Surgical intervention can include instrumentation (e.g., implantation of hardware, such as screws, rods, plates, and metal cages) to aid in bone fusion. Surgical intervention can include traditional open surgery, such as open neck or open back surgery, a minimally invasive surgery, or a combination thereof. 
     Bone Morphogenetic Protein 
     Administration of sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1, or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) in any of the disclosed methods can occur in conjunction with administration of bone morphogenetic protein (BMP). The use of BMP to induce bone formation and bone healing (e.g., arthrodesis or treating a bone fracture) is known. In one embodiment, treating at least one symptom of neurofibromatosis type 1, treating at least one symptom of dystrophic scoliosis, or inducing bone healing occurs in conjunction with administration of BMP. A BMP can be administered directly to the affected area, e.g., a bone fracture, or by subcutaneous, intramuscular, intravenous, oral, nasal, sublingual, intrathecal, or intradermal administration. In one embodiment, BMP is administered during a physical intervention, for instance, surgical intervention. The BMP can be any BMP effective to induce bone formation. Examples of useful BMPs are BMP-2, BMP-4, and BMP-7. BMP gene sequences, protein sequences, and methods for producing recombinant and naturally-derived BMPs are known in the art. BMPs may be administered on collagen absorbable sponges admixed with freeze dried crushed cancellous allograft bone. 
     Bisphosphonates 
     Administration of sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) in any of the disclosed methods can occur in conjunction with administration of at least one bisphosphonate. In one embodiment, treating at least one symptom of neurofibromatosis type 1, treating at least one symptom of dystrophic scoliosis, or inducing bone healing occurs in conjunction with administration of at least one bisphosphonate. The use of at least one bisphosphonate to prevent the loss of bone density is known in the art and routine. Examples of bisphosphonates include, but are not limited to, zolendronic acid and pamidronate. 
     In one embodiment, at least one bisphosphonate is administered during or after a physical intervention, for instance, surgical intervention. For instance, at least one bisphosphonate can be provided in either a single or multiple dosage regimens. One or more doses can be administered, e.g., hourly, every other hour, daily, every other day, twice a week, three times a week, four times a week, five times a week, six times a week, weekly, biweekly, monthly, bimonthly, or yearly. Alternatively, doses can be administered, e.g., twice, three times, four times, five times, six times, seven times, eight times, nine times, 10 times, 11 times, or 12 times per day. In one embodiment, the dosing regimen is a single administration. The duration of the dosing regimen can be, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 day(s), week(s), or month(s). In one embodiment, the administration can begin 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 day(s), week(s), or month(s) after the physical intervention, for instance, surgical intervention. The at least one bisphosphonate can be delivered at a dosage of, e.g., 0.01, 0.05, 0.1, 0.5, 1, 2, 2.5, 5, 10, 20, 25, 50, 100, 125, 150, 200, 250, or 500 mg/kg; or 1, 2, 2.5, 5, 10, 20, 25, 50, 100, 125, 150, 200, 250, 500, 750, 900, or 1,000 mg/kg. The at least one bisphosphonate can be administered by subcutaneous, intramuscular, intravenous, oral, nasal, sublingual, intrathecal, or intradermal administration. In one embodiment, the pharmaceutical composition is formulated for intravenous administration. The amount, frequency, and duration of dosage will be adapted by the clinician in accordance with conventional factors presented by the patient, such as the symptoms of the neurofibromatosis type 1, the dystrophic scoliosis, the need for bone healing/mineralization, and different parameters from the patient. 
     Evaluation of Treatment Efficacy 
     Exemplary metrics useful for evaluating the efficacy of treatment using a sALP (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) include (1) bone healing, (2) bone mineralization, (3) bone mineral density, and (4) plasma PPi and PLP concentrations. The methods may further include the use of one or more of the described metrics (e.g., bone healing, mineralization, bone mineral density, or plasma PPi and PLP concentrations), singly or in combination, to assess treatment efficacy, in which improvements as described herein demonstrate that sALP is an effective treatment for the treated condition. Additionally, the method may further include changing the dosage and/or frequency of sALP (e.g., SEQ ID NO: 1; e.g., asfotase alfa) administration in order to determine the effective amount of sALP to administer to patient in need thereof. 
     Bone Healing and Mineralization 
     In some instances, administration of sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1, or a polypeptide variant described herein, such as a variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) according to the disclosure results in an increase in bone healing in the patient following the treatment. An increase in bone healing results in new bone, and includes the increased mineralization to result in the union of two or more bones (e.g., fusion of two normally separate bones, or union of two portions of a bone that have been separated by a fracture), or increased bone healing near instrumentation. Methods for identifying an increase in bone healing and mineralization are routine and include non-invasive techniques such as radiography and computed tomography (CT). Typically, images of the relevant area of the patient are taken before and at one or more time points following the treatment method, and the images are compared. Increased bone healing and/or mineralization can be identified as increased opacity. Thus, successful arthrodesis can be identified as increased opacity after treatment between two bones targeted for fusion. Reduced loosening of hardware in bone, e.g., screws, can be identified as increased opacity in the bone surrounding, e.g., anchoring, the instrumentation. Pre-treatment images can be taken at any time before the treatment method begins, and can be timed to be 1, 2, 3, 4, 5, or 6 day(s), week(s), or month(s) before treatment is initiated. Post-treatment images can be taken 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 day(s), week(s), month(s), or year(s) after treatment is initiated. The increase in bone healing and/or mineralization in the patient may become detectable at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 week(s) or month(s) following a treatment period. The increase in bone healing and/or mineralization in the patient may in some cases be sustained for at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 week(s), month(s), or year(s) following a treatment period. A reference bone can be one or more specific bones. In one embodiment, the reference point is the one or more specific bones being fused (e.g., tibia, radius, ulna, and spinal bones, e.g., vertebrae, e.g., cervical spine C1-C7, thoracic spine T1-T12, lumbar spine L1-L5, sacrum S1-S5, and coccyx). by a disclosed method. In one embodiment, the reference point is the specific bone having a fracture that is being treated by a disclosed method. In one embodiment, the reference point is the bone surrounding instrumentation. 
     Bone Mineral Density (BMD) 
     In some instances, administration of sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1, or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) according to the disclosure results in a limited change in BMD in the patient following the treatment. Methods for measuring BMD are known and include, for instance, bone biopsy, dual-energy X-ray absorptiometry (DXA or DEXA), peripheral quantitative CT (pQCT), high-resolution pQCT (HR-pQCT), and quantitative ultrasound (QUS). Measurement can be by any method, including CT Hounsfield measurement, and can use comparison of results to a normative database or control patient. BMD is typically reported as a Z-score or a T-score. Pre-treatment BMD values can be measured at any time before the treatment method begins, and can be timed to be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 day(s), week(s), month(s), or year(s) before treatment is initiated. Post-treatment BMD values can be measured 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 day(s), week(s), month(s), or year(s) after treatment is initiated. In one embodiment, the BMD value of a reference point after treatment is decreased by no greater than 0.01%, 0.05%, 0.1%, 0.5%, 1%. In one embodiment, the BMD value of a reference point after treatment is increased by at least 0.01%, 0.05%, 0.1%, 0.5%, or 1%. In one embodiment, the change in a BMD value of a reference point after treatment is unchanged, or a change is undetectable. The change in BMD of the patient may in some cases be sustained following a treatment period for at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 day(s), week(s), month(s), or year(s) or years or more. A reference point can be, e.g., one or more specific bones. In one embodiment, the reference point is the one or more specific bone(s) being treated by a disclosed method. 
     PPi and PLP Concentrations 
     The average decrease in PPi concentrations in a plasma sample from the patient to whom the sALP or sALP polypeptide (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) is administered according to the disclosure may be about 25% or greater (e.g., 30%, 35%, 40%, 45%, 50%, 55%, 60%, or more than 60%) relative to PPi concentrations in a plasma sample from the patient prior to administration of the sALP. The average decrease in PPi concentrations in a plasma sample from the patient may in some cases be sustained during a treatment period of at least one week, six months, or up to one year or more. Typically, the decrease is sustained for the duration of the treatment period with asfotase alfa. 
     The average decrease in PLP concentrations in a plasma sample from the patient to whom the sALP or sALP polypeptide (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) is administered may be about 50% or greater (e.g., 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or more than 95%) relative to PLP concentrations in a plasma sample from the patient prior to administration of the sALP. The average decrease in PLP concentrations in a plasma sample from the patient may in some cases be sustained during a treatment period of at least one week and up to one year or more. Typically, the decrease is sustained for the duration of the treatment period with asfotase alfa. 
     Alkaline Phosphatase 
     Asfotase alfa is a human TNALP (hTNALP; SEQ ID NO: 1) fusion polypeptide. In particular, asfotase alfa (SEQ ID NO: 1) can be used effectively to treat at least one symptom of neurofibromatosis type 1, treat at least one symptom of dystrophic scoliosis, or induce bone healing, and physical impairments associated therewith. 
     Given the results described herein, the treatment methods are not limited to administration of a particular alkaline phosphatase (ALP) or nucleic acid sequence encoding an ALP. Alkaline phosphatases encompass a group of enzymes that catalyze the cleavage of a phosphate moiety (e.g., hydrolysis of pyrophosphate, PPi). There are four known mammalian alkaline phosphatase (ALP) isozymes: tissue nonspecific alkaline phosphatase (TNALP; described further below), placental alkaline phosphatase (PLALP) (e.g., Accession Nos. P05187, NP_112603, and NP_001623), germ cell alkaline phosphatase (GALP) (e.g., Accession No. P10696), and intestinal alkaline phosphatase (IALP) (e.g., Accession Nos. P09923 and NP_001622). In addition to the exemplary ALPs discussed herein, any polypeptide having the identical or similar catalytic site structure and/or enzymatic activity of ALP can be used (e.g., as a sALP or a sALP fusion polypeptide as defined herein) in a method disclosed herein. Bone delivery conjugates including sALP are further described in PCT Publication Nos: WO 2005/103263 and WO 2008/138131. 
     TNALPs that can be used according to the methods described herein include, e.g., human TNALP (Accession Nos. NP_000469, AA10910, AAH90861, AAH66116, AAH21289, and AAl26166), rhesus TNALP (Accession No. XP_01109717), rat TNALP (Accession No. NP_037191), dog TNALP (Accession No. AAF64516), pig TNALP (Accession No. AAN64273), mouse (Accession No. NP_031457), cow TNALP (Accession Nos. NP_789828, NP_776412, AAM 8209, and AAC33858), and cat TNALP (Accession No. NP_001036028). In particular, TNALP can be a recombinant human TNALP (e.g., SEQ ID NO: 1, asfotase alfa; see U.S. Pat. Nos. 7,763,712 and 7,960,529) used in a method disclosed herein. The TNALP can also be one that exhibits at least about 95% sequence identity to the polypeptide or nucleic acid sequence of the above-noted TNALPs. 
     Soluble Alkaline Phosphatases 
     An ALP that can be used in the methods described herein includes soluble (e.g., extracellular or non-membrane-bound) forms of any of the alkaline phosphatases described herein. The sALP can be, for example, a soluble form of human tissue non-specific alkaline phosphatase (human TNALP (hTNALP)). The methods are not limited to a particular sALP and can include any sALP that is physiologically active toward, e.g., phosphoethanolamine (PEA), inorganic pyrophosphate (PPi), and pyridoxal 5′-phosphate (PLP). In particular, a sALP is one that is catalytically competent to improve skeletal mineralization in bone. The methods further include nucleic acids encoding the sALPs described herein that can be used in a method described herein. 
     TNALP is a membrane-bound protein anchored by a glycolipid moiety at the C-terminal (Swiss-Prot, P05186). This glycolipid anchor (GPI) is added post-translationally after the removal of a hydrophobic C-terminal end, which serves both as a temporary membrane anchor and as a signal for the addition of the GPI. While the GPI anchor is located in the cell membrane, the remaining portions of TNALP are extracellular. In particular, TNALP (e.g., human TNALP (hTNALP)) can be engineered to replace the first amino acid of the hydrophobic C-terminal sequence (an alanine) with a stop codon, thereby producing an engineered hTNALP that contains all amino acid residues of the native anchored form of TNALP and lacks the GPI membrane anchor. One skilled in the art will appreciate that the position of the GPI membrane anchor will vary in different ALPs and can include, e.g., the last 10, 12, 14, 16, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 34, 36, 38, 40, 45, 50, or more amino acid residues on the C-terminus of the polypeptide. Recombinant sTNALP can include, e.g., amino acids 1 to 502 (18 to 502 when secreted), amino acids 1 to 501 (18 to 501 when secreted), amino acids 1 to 504 (18 to 504 when secreted), amino acids 1 to 505 (18-505 when secreted), or amino acids 1 to 502. Thus, the C-terminal end of the native ALP can be truncated by certain amino acids without affecting ALP activity. 
     In addition to the C-terminal GPI anchor, TNALP also has an N-terminal signal peptide sequence. The N-terminal signal peptide is present on the synthesized protein when it is synthesized, but cleaved from TNALP after translocation into the ER. The sALPs include both secreted (i.e., lacking the N-terminal signal) and non-secreted (i.e., having the N-terminal signal) forms thereof. One skilled in the art will appreciate that the position of the N-terminal signal peptide will vary in different alkaline phosphatases and can include, for example, the first 5, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 30, or more amino acid residues on the N-terminus of the polypeptide. One of skill in the art can predict the position of a signal sequence cleavage site, e.g., by an appropriate computer algorithm such as that described in Bendtsen et al. (J. Mol. Biol. 340(4):783-795, 2004) and available on the Web at www.cbs.dtu.dk/services/SignalP/. 
     The methods can also be performed using sALP consensus sequences derived from the extracellular domain of ALP isozymes (e.g., TNALP, PALP, GCALP, IALP, etc.). Thus, similar to sTNALP discussed above, the present disclosure also provides other soluble human ALP isozymes, i.e., without the peptide signal, preferably comprising the extracellular domain of the ALPs. The sALPs also include polypeptide sequences satisfying a consensus sequence derived from the ALP extracellular domain of human ALP isozymes and of mammalian TNALP orthologs (human, mouse, rat, cow, cat, and dog) or a consensus derived from the ALP extracellular domain of just mammalian TNALP orthologs (human, mouse, rat, cow, cat, and dog). The sALPs also include those which satisfy similar consensus sequences derived from various combinations of these TNALP orthologs or human ALP isozymes. Such consensus sequences are given, for example, in WO 2008/138131. 
     sALPs of the present methods can include not only the wild-type sequence of the sALPs described above, but any polypeptide having at least 50% (e.g., 55%, 60%, 65%, 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more) sequence identity to these alkaline phosphatases (e.g., SEQ ID NOs: 1-19; for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa). Examples of mutations that can be introduced into an ALP sequence are described in US Publication No. 2013/0323244. A sALP can optionally be glycosylated at any appropriate one or more amino acid residues. In addition, an sALP can have at least 50% (e.g., 55%, 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more) sequence identity to any of the sALPs described herein (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa). A sALP can have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more additions, deletions, or substitutions relative to any of the sALPs described herein (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa). 
     sALP Fusion Polypeptides 
     Any of the sALPs (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa), linkers, spacers (e.g., Fc regions), and bone-targeting moieties described herein can be combined in a fusion polypeptide, which includes the structures Z-sALP-Y-spacer-X-Wn-V, Z-Wn-X-spacer-Y-sALP-V, Z-sALP-Y-Wn-X-spacer-V, and Z-Wn-X-sALP-Y-spacer-V. In particular, the structure of the sALP fusion polypeptide can be Z-sALP-Y-spacer-X-Wn-V or Z-Wn-X-spacer-Y-sALP-V. The sALP of the sALP fusion polypeptide can be the full-length ALP or functional fragments of ALPs, such as the soluble, extracellular domain of the ALP, as is described herein (e.g., TNALP, PALP, GCALP and IALP). 
     Any one of X, Y, Z, and V and/or the spacer can be absent or a linker region including an amino acid sequence of at least one amino acid. For example, X, Y, Z, and V may be a dipeptide sequence (e.g., leucine-lysine or aspartic acid-isoleucine), such as a two residue linker at the Y position (e.g., leucine-lysine) or a two residue linker at the X position (e.g., aspartic acid-isoleucine). For example, sALP fusion polypeptides can have the structure hTNALP-Fc-D10 (e.g., a sALP fusion polypeptide including the amino acid sequence of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa). 
     The linker region can be of any sequence and length that allows the sALP to remain biologically active, e.g., not sterically hindered. Exemplary linker lengths are between 1 and 200 amino acid residues, e.g., 1-5, 6-10, 11-15, 16-20, 21-25, 26-30, 31-35, 36-40, 41-45, 46-50, 51-55, 56-60, 61-65, 66-70, 71-75, 76-80, 81-85, 86-90, 91-95, 96-100, 101-110, 111-120, 121-130, 131-140, 141-150, 151-160, 161-170, 171-180, 181-190, or 191-200 amino acid residues. For instance, linkers include or consist of flexible portions, e.g., regions without significant fixed secondary or tertiary structure. Exemplary flexible linkers are glycine-rich linkers, e.g., containing at least 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or even 100% glycine residues. Linkers can also contain, e.g., serine residues. In some cases, the amino acid sequence of linkers consists only of glycine and serine residues. A linker can optionally be glycosylated at any appropriate one or more amino acid residues. Additionally, a linker as described herein can include any other sequence or moiety, attached covalently or non-covalently. The linker can also be absent, in which the spacer (e.g., the Fc region) and the sALP are fused together directly, with no intervening residues. 
     Useful spacers include, but are not limited to, polypeptides comprising an Fc region. For example, a sALP can be a fusion polypeptide including an Fc region of an immunoglobulin at the N-terminal or C-terminal domain. An immunoglobulin molecule has a structure that is well known in the art. It includes two light chains (˜23 kD each) and two heavy chains (˜50-70 kD each) joined by inter-chain disulfide bonds. Immunoglobulins are readily cleaved proteolytically (e.g., by papain cleavage) into Fab (containing the light chain and the VH and CH1 domains of the heavy chain) and Fc (containing the CH2 and CH3 domains of the heavy chain, along with adjoining sequences). Useful Fc fragments as described herein include the Fc fragment of any immunoglobulin molecule, including IgG, IgM, IgA, IgD, or IgE, and their various subclasses (e.g., IgG-1, IgG-2, IgG-3, IgG-4, IgA-1, IgA-2), from any mammal (e.g., human). For instance, the Fc fragment is human IgG-1. The Fc fragments can include, for example, the CH2 and CH3 domains of the heavy chain and any portion of the hinge region. The Fc region can optionally be glycosylated at any appropriate one or more amino acid residues known to those skilled in the art. In particular, the Fc fragment of the fusion polypeptide has the amino acid sequence of SEQ ID NO: 20, or has at least 50% (e.g., 55%, 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more) sequence identity to SEQ ID NO: 20. Engineered, e.g., non-naturally occurring, Fc regions can be incorporated into the sALP fusion polypeptides described herein, e.g., those described in WO 2005/007809. An Fc fragment as described herein can have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 50, or more additions, deletions, or substitutions relative to any of the Fc fragments described herein. 
     Wn can be a bone-targeting moiety, e.g., having a series of consecutive aspartate (D) or glutamate (E) residues, in which n=1 to 50, e.g., n=3-30, e.g., 5-15, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 36, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50. The bone-targeting moiety, if present, can be positioned anywhere in the fusion polypeptide, e.g., at or near the N-terminal or C-terminal end, and/or in the linker region. For instance, the bone-targeting moiety can be present at the C-terminal end of a sALP fusion polypeptide. sALPs and fusion polypeptides can also lack a bone-targeting moiety. 
     Additional amino acid residues can be introduced into the polypeptide according to the cloning strategy used to produce the fusion polypeptides. For instance, the additional amino acid residues do not provide an additional GPI anchoring signal so as to maintain the polypeptide in a soluble form. Furthermore, any such additional amino acid residues, when incorporated into the polypeptide of the methods, do not provide a cleavage site for endoproteases of the host cell. The likelihood that a designed sequence would be cleaved by the endoproteases of the host cell can be predicted as described, e.g., by Ikezawa ( Biol. Pharm. Bull.  25:409-417, 2002). 
     The sALP fusion polypeptides (such as a TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be associated into dimers or tetramers. For example, two sALP-Fc monomers can be covalently linked through two disulfide bonds located in the hinge regions of the Fc fragments. Additionally, the sALP fusion polypeptide (e.g., a sALP or a sALP fusion polypeptide) can be glycosylated or PEGylated. 
     Production of Nucleic Acids and Polypeptides 
     The nucleic acids encoding sALPs (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be produced by any method known in the art. Typically, a nucleic acid encoding the desired fusion polypeptide is generated using molecular cloning methods, and is generally placed within a vector, such as a plasmid or virus. The vector is used to transform the nucleic acid into a host cell appropriate for the expression of the fusion polypeptide. Representative methods are disclosed, for example, in Maniatis et al. (Cold Springs Harbor Laboratory, 1989). Many cell types can be used as appropriate host cells, although mammalian cells are preferable because they are able to confer appropriate post-translational modifications. Host cells can include, e.g., Chinese Hamster Ovary (CHO) cell, L cell, C127 cell, 3T3 cell, BHK cell, COS-7 cell or any other suitable host cell known in the art. For example, the host cell is a Chinese Hamster Ovary (CHO) cell (e.g., a CHO-DG44 cell). 
     The sALPs (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be produced under any conditions suitable to effect expression of the sALP polypeptide in the host cell. Such conditions include appropriate selection of a media prepared with components such as a buffer, bicarbonate and/or HEPES, ions like chloride, phosphate, calcium, sodium, potassium, magnesium, iron, carbon sources like simple sugars, amino acids, potentially lipids, nucleotides, vitamins and growth factors like insulin; regular commercially available media like alpha-MEM, DMEM, Ham&#39;s-F12, and IMDM supplemented with 2-4 mM L-glutamine and 5% Fetal bovine serum; regular commercially available animal protein free medialike Hyclone™ SFM4CHO, Sigma CHO DHFR-, Cambrex POWER™ CHO CD supplemented with 2-4 mM L-glutamine. These media are desirably prepared without thymidine, hypoxanthine and L-glycine to maintain selective pressure, allowing stable protein-product expression. 
     Patient Treated by the Methods 
     The patient to whom sALP is administered can be of any age, but particularly can be an adolescent, e.g., a person of about 12 to about 18 years of age, or an adult older than about 18 years of age. The patient may be afflicted with at least one symptom of neurofibromatosis type 1. The patient may be afflicted with dystrophic scoliosis. The patient may be in need of induced bone healing and/or mineralization. For instance, the patient may be afflicted with one or more bone fractures, such as fractures in spinal bones, e.g., vertebrae. The patient may have at least one symptom of dystrophic scoliosis, including NF1-related dystrophic scoliosis. 
     Administration and Dosage 
     In any of the disclosed methods, any amount of a pharmaceutical composition (e.g., including a sALP or sALP fusion polypeptide, such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant described herein, such as a variant having at least 80, 85%, 90%, 95%, 97%, 99%, or 100% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be administered to a patient. The dosages will depend on many factors including the mode of administration and the age of the patient. Typically, the amount of the composition (e.g., a sALP or sALP fusion polypeptide, such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) contained within a single dose will be an amount that is effective to treat a patient described herein without inducing significant toxicity. 
     For example, in any of the disclosed methods the sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) described herein can be administered to a patient in individual doses ranging, e.g., from 0.01 mg/kg to 500 mg/kg (e.g., from 0.05 mg/kg to 500 mg/kg, from 0.1 mg/kg to 20 mg/kg, from 5 mg/kg to 500 mg/kg, from 0.1 mg/kg to 100 mg/kg, from 10 mg/kg to 100 mg/kg, from 0.1 mg/kg to 50 mg/kg, from 0.5 mg/kg to 25 mg/kg, from 1.0 mg/kg to 10 mg/kg, from 1.5 mg/kg to 5 mg/kg, or from 2.0 mg/kg to 3.0 mg/kg) or from 1 μg/kg to 1,000 μg/kg (e.g., from 5 μg/kg to 1,000 μg/kg, from 1 μg/kg to 750 μg/kg, from 5 μg/kg to 750 μg/kg, from 10 μg/kg to 750 μg/kg, from 1 μg/kg to 500 μg/kg, from 5 μg/kg to 500 μg/kg, from 10 μg/kg to 500 μg/kg, from 1 μg/kg to 100 μg/kg, from 5 μg/kg to 100 μg/kg, from 10 μg/kg to 100 μg/kg, from 1 μg/kg to 50 μg/kg, from 5 μg/kg to 50 μg/kg, or from 10 μg/kg to 50 μg/kg). 
     Exemplary doses of a sALP include, e.g., 0.01, 0.05, 0.1, 0.5, 1, 2, 2.5, 5, 10, 20, 25, 50, 100, 125, 150, 200, 250, or 500 mg/kg; or 1, 2, 2.5, 5, 10, 20, 25, 50, 100, 125, 150, 200, 250, 500, 750, 900, or 1,000 μg/kg. For all dosages or ranges recited herein, the term “about” can be used to modify these dosages by ±10% of the recited values or range endpoints. In particular, compositions (e.g., including sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa)) in accordance with the present disclosure can be administered to a patient in doses ranging from about 0.001 mg/kg/day to about 500 mg/kg/day, about 0.01 mg/kg/day to about 100 mg/kg/day, or about 0.01 mg/kg/day to about 20 mg/kg/day. For example, the sALP compositions (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be administered to a patient in a weekly dosage ranging, e.g., from about 0.5 mg/kg/week to about 140 mg/kg/week, e.g., about 0.8 mg/kg/week to about 50 mg/kg/week, or about 1 mg/kg/week to about 10 mg/kg/week (e.g., about 3 or about 6 or about 9 mg/kg/week). In particular, the sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be administered at a dosage of 2 mg/kg three times a week (total dose about 6 mg/kg/week), 1 mg/kg six times a week (total dose about 6 mg/kg/week), 3 mg/kg three times a week (total dose 9 mg/kg/week), 0.5 mg/kg three times a week (total dose of 1.5 mg/kg/week), or 9.3 mg/kg three times a week (total dose about 28 mg/kg/week). The dosage will be adapted by the clinician in accordance with conventional factors such as, for instance, the extent of the neurofibromatosis type 1, the dystrophic scoliosis, the need for bone healing, and different parameters from the patient. 
     Dosages of pharmaceutical compositions including sALPs (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be provided in either a single or multiple dosage regimens. Doses can be administered, e.g., hourly, bihourly, daily, bidaily, twice a week, three times a week, four times a week, five times a week, six times a week, weekly, biweekly, monthly, bimonthly, or yearly. Alternatively, doses can be administered, e.g., twice, three times, four times, five times, six times, seven times, eight times, nine times, 10 times, 11 times, or 12 times per day. In particular, the dosing regimen is three times a week. The duration of the dosing regimen can be, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 day(s), week(s), or month(s). The dosing regimen can begin before, during, or after a physical intervention, such as a surgical intervention. The amount, frequency, and duration of dosage will be adapted by the clinician in accordance with conventional factors such as the extent of the neurofibromatosis type 1, the dystrophic scoliosis, the bone fracture, or bone mineralization, and different parameters from the patient. 
     For example, a sALP or sALP fusion polypeptide (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be formulated as a solution for injection, which is a clear, colorless to slightly yellow, aqueous solution, pH 7.4. The sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) may be formulated at a concentration of, for instance, 12 mg/0.3 mL, 18 mg/0.45 mL, 28 mg/0.7 mL, 40 mg/l ml, or 80 mg/0.8 mL. In particular, the composition can be formulated as a 40 mg/ml solution for injection, in which each ml of solution contains 40 mg of sALP (e.g., each vial contains 0.3 ml solution and 12 mg of sALP (40 mg/ml), each vial contains 0.45 ml solution and 18 mg of sALP (40 mg/ml), each vial contains 0.7 ml solution and 28 mg of sALP (40 mg/ml), or each vial contains 1.0 ml solution and 40 mg of asfotase alfa (40 mg/ml)). A sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be formulated as a solution for injection at a concentration of 100 mg/ml, in which each 1 ml of solution contains 100 mg of sALP or sALP polypeptide (e.g., each vial contains 0.8 ml solution and 80 mg of asfotase alfa (100 mg/ml)). 
     For example, the recommended dosage of a sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) is 2 mg/kg of body weight administered subcutaneously three times per week, or a dosage regimen of 1 mg/kg of body weight administered subcutaneously six times per week. Additional dosage information is provided below (Table 1). 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 DOSING OF ASFOTASE ALFA 
               
            
           
           
               
               
               
            
               
                   
                 If injecting 3x per week 
                 If injecting 6 x per week 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Body 
                 Dose to 
                 Volume 
                 Vial type 
                 Dose to 
                 Volume 
                 Vial type 
               
               
                 Weight 
                 be 
                 to be 
                 used for 
                 be 
                 to be 
                 used for 
               
               
                 (kg) 
                 injected 
                 injected 
                 injection 
                 injected 
                 injected 
                 injection 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 3 
                  6 mg 
                 0.15 ml 
                  0.3 ml 
                   
                   
                   
               
               
                 4 
                  8 mg 
                 0.20 ml 
                  0.3 ml 
                   
                   
                   
               
               
                 5 
                 10 mg 
                 0.25 ml 
                  0.3 ml 
                   
                   
                   
               
               
                 6 
                 12 mg 
                 0.30 ml 
                  0.3 ml 
                   6 mg 
                 0.15 ml 
                  0.3 ml 
               
               
                 7 
                 14 mg 
                 0.35 ml 
                 0.45 ml 
                   7 mg 
                 0.18 ml 
                  0.3 ml 
               
               
                 8 
                 16 mg 
                 0.40 ml 
                 0.45 ml 
                   8 mg 
                 0.20 ml 
                  0.3 ml 
               
               
                 9 
                 18 mg 
                 0.45 ml 
                 0.45 ml 
                   9 mg 
                 0.23 ml 
                  0.3 ml 
               
               
                 10 
                 20 mg 
                 0.50 ml 
                  0.7 ml 
                  10 mg 
                 0.25 ml 
                  0.3 ml 
               
               
                 11 
                 22 mg 
                 0.55 ml 
                  0.7 ml 
                  11 mg 
                 0.28 ml 
                  0.3 ml 
               
               
                 12 
                 24 mg 
                 0.60 ml 
                  0.7 ml 
                  12 mg 
                 0.33 ml 
                  0.3 ml 
               
               
                 13 
                 26 mg 
                 0.65 ml 
                  0.7 ml 
                  13 mg 
                 0.35 ml 
                 0.45 ml 
               
               
                 14 
                 28 mg 
                 0.70 ml 
                  0.7 ml 
                  14 mg 
                 0.35 ml 
                 0.45 ml 
               
               
                 15 
                 30 mg 
                 0.75 ml 
                   1 ml 
                  15 mg 
                 0.38 ml 
                 0.45 ml 
               
               
                 16 
                 32 mg 
                 0.80 ml 
                   1 ml 
                  16 mg 
                 0.40 ml 
                 0.45 ml 
               
               
                 17 
                 34 mg 
                 0.85 ml 
                   1 ml 
                  17 mg 
                 0.43 ml 
                 0.45 ml 
               
               
                 18 
                 36 mg 
                 0.90 ml 
                   1 ml 
                  18 mg 
                 0.45 ml 
                 0.45 ml 
               
               
                 19 
                 38 mg 
                 0.95 ml 
                   1 ml 
                  19 mg 
                 0.48 ml 
                  0.7 ml 
               
               
                 20 
                 40 mg 
                 1.00 ml 
                   1 ml 
                  20 mg 
                 0.50 ml 
                  0.7 ml 
               
               
                 25 
                 50 mg 
                 0.50 ml 
                  0.8 ml 
                  25 mg 
                 0.63 ml 
                  0.7 ml 
               
               
                 30 
                 60 mg 
                 0.60 ml 
                  0.8 ml 
                  30 mg 
                 0.75 ml 
                   1 ml 
               
               
                 35 
                 70 mg 
                 0.70 ml 
                  0.8 ml 
                  35 mg 
                 0.88 ml 
                   1 ml 
               
               
                 40 
                 80 mg 
                 0.80 ml 
                  0.8 ml 
                  40 mg 
                 1.00 ml 
                   1 ml 
               
               
                 50 
                   
                   
                   
                  50 mg 
                 0.50 ml 
                  0.8 ml 
               
               
                 60 
                   
                   
                   
                  60 mg 
                 0.60 ml 
                  0.8 ml 
               
               
                 70 
                   
                   
                   
                  70 mg 
                 0.70 ml 
                  0.8 ml 
               
               
                 80 
                   
                   
                   
                  80 mg 
                 0.80 ml 
                  0.8 ml 
               
               
                 90 
                   
                   
                   
                  90 mg 
                 0.90 ml 
                  0.8 ml (×2) 
               
               
                 100 
                   
                   
                   
                 100 mg 
                 1.00 ml 
                  0.8 ml (×2) 
               
               
                   
               
            
           
         
       
     
     In some instances, administration of the sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) according to the disclosure can result in one or more of the following: (i) an increase in bone healing in the patient; and/or (ii) a change in bone mineral density that is undetectable or increased. 
     In any of the aspects disclosed herein, the patient exhibits tolerability to administration of the sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa), such as a lack of or decreased incidence of adverse events selected from the group consisting of injection site erythema, decrease in hemoglobin, pyrexia, pneumonia, upper respiratory tract infection, otitis media, vomiting, constipation, diarrhea, tooth loss, nasopharyngitis, rash, dental carries, and irritability. 
     In any of the aspects disclosed herein, the sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) is formulated in a pharmaceutical composition, with at least one pharmaceutically acceptable carrier, such as saline (e.g., sodium chloride and sodium phosphate). For example, the at least one pharmaceutically acceptable carrier can include 150 mM sodium chloride and 25 mM sodium phosphate. 
     In any of the above aspects, the sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) is physiologically active toward PEA, PPi, and PLP, catalytically competent to improve skeletal mineralization in bone, and/or is the soluble extracellular domain of an alkaline phosphatase. 
     Formulations 
     The pharmaceutical compositions including sALPs (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be formulated according to standard methods. Pharmaceutical formulation is a well-established art, and is further described in, e.g., Gennaro (2000)  Remington: The Science and Practice of Pharmacy,  20th Edition, Lippincott, Williams &amp; Wilkins (ISBN: 0683306472); Ansel et al. (1999)  Pharmaceutical Dosage Forms and Drug Delivery Systems,  7th Edition, Lippincott Williams &amp; Wilkins Publishers (ISBN: 0683305727); and Kibbe (2000)  Handbook of Pharmaceutical Excipients , American Pharmaceutical Association, 3rd Edition (ISBN: 091733096X). For instance, a sALP composition (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be formulated, for example, as a buffered solution at a suitable concentration and suitable for storage at 2-8° C. (e.g., 4° C.). A composition can also be formulated for storage at a temperature below 0° C. (e.g., −20° C. or −80° C.). A composition can further be formulated for storage for up to 2 years (e.g., one month, two months, three months, four months, five months, six months, seven months, eight months, nine months, 10 months, 11 months, 1 year, 1½ years, or 2 years) at 2-8° C. (e.g., 4° C.). Thus, the compositions described herein can be stable in storage for at least 1 year at 2-8° C. (e.g., 4° C.). 
     The pharmaceutical compositions including sALPs (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be in a variety of forms. These forms include, e.g., liquid, semi-solid and solid dosage forms, such as liquid solutions (e.g., injectable and infusible solutions), dispersions or suspensions, tablets, pills, powders, liposomes and suppositories. The preferred form depends, in part, on the intended mode of administration and therapeutic application. 
     For example, compositions intended for systemic or local delivery can be in the form of injectable or infusible solutions. Accordingly, the compositions including sALPs (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be formulated for administration by a parenteral mode (e.g., subcutaneous, intravenous, intraperitoneal, or intramuscular injection). 
     The pharmaceutical compositions including sALPs (such as TNALP, for example the sALP fusion polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be formulated as a solution, microemulsion, dispersion, liposome, or other ordered structure suitable for stable storage at high concentration. Sterile injectable solutions can be prepared by incorporating a composition described herein in the required amount in an appropriate solvent with one or a combination of ingredients enumerated above, as required, followed by filter sterilization. Generally, dispersions are prepared by incorporating a composition described herein into a sterile vehicle that contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, methods for preparation include vacuum drying and freeze-drying that yield a powder of a composition described herein plus any additional desired ingredient (see herein) from a previously sterile-filtered solution thereof. The proper fluidity of a solution can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. Prolonged absorption of injectable compositions can be brought about by including in the composition a reagent that delays absorption, for example, monostearate salts, and gelatin. 
     The pharmaceutical compositions described herein can also be formulated in immunoliposome compositions. Such formulations can be prepared by methods known in the art such as, e.g., the methods described in Epstein et al. (1985)  Proc Natl Acad Sci USA  82:3688; Hwang et al. (1980)  Proc Natl Acad Sci USA  77:4030; and U.S. Pat. Nos. 4,485,045 and 4,544,545. Liposomes with enhanced circulation time are disclosed in, e.g., U.S. Pat. No. 5,013,556. 
     Pharmaceutical compositions including sALPs (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can also be formulated with a carrier that will protect the composition (e.g., a sALP polypeptide or sALP fusion polypeptide) against rapid release, such as a controlled release formulation, including implants and microencapsulated delivery systems. Biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Many methods for the preparation of such formulations are known in the art. See, e.g., J. R. Robinson (1978)  Sustained and Controlled Release Drug Delivery Systems , Marcel Dekker, Inc., New York. 
     When compositions are to be used in combination with a second active agent, the compositions can be co-formulated with the second agent, or the compositions can be formulated separately from the second agent formulation. For example, the respective pharmaceutical compositions can be mixed, e.g., just prior to administration, and administered together or can be administered separately, e.g., at the same or different times. 
     Carriers/Vehicles 
     Preparations containing a sALP (such as TNALP, for example the sALP polypeptide of SEQ ID NO: 1 or a polypeptide variant having at least 95% sequence identity to the sequence of SEQ ID NO: 1, e.g., asfotase alfa) can be provided to a patient, such as a patient having at least one symptom of neurofibromatosis type 1, at least one symptom of dystrophic scoliosis, or in need of bone healing, in combination with pharmaceutically acceptable sterile aqueous or non-aqueous solvents, suspensions or emulsions. Examples of non-aqueous solvents are propylene glycol, polyethylene glycol, vegetable oil, fish oil, and injectable organic esters. Aqueous carriers include water, water-alcohol solutions, emulsions or suspensions, including saline and buffered medical parenteral vehicles including sodium chloride solution, Ringer&#39;s dextrose solution, dextrose plus sodium chloride solution, Ringer&#39;s solution containing lactose, or fixed oils. For example, the pharmaceutically acceptable carrier can include sodium chloride and/or sodium phosphate, in which the composition includes, e.g., about 150 mM sodium chloride and/or about 25 mM sodium phosphate, pH 7.4. 
     Intravenous vehicles can include fluid and nutrient replenishers, electrolyte replenishers, such as those based upon Ringer&#39;s dextrose, and the like. Pharmaceutically acceptable salts can be included therein, for example, mineral acid salts such as hydrochlorides, hydrobromides, phosphates, sulfates, and the like; and the salts of organic acids such as acetates, propionates, malonates, benzoates, and the like. Additionally, auxiliary substances, such as wetting or emulsifying agents, pH buffering substances, and the like, can be present in such vehicles. A thorough discussion of pharmaceutically acceptable carriers is available in  Remington&#39;s Pharmaceutical Sciences  (Mack Pub. Co., N.J. 1991). 
     EXAMPLES 
     The following example is intended to illustrate, rather than limit, the disclosure. It is to be understood that the particular examples, materials, amounts, and procedures are to be interpreted broadly in accordance with the scope and spirit of the disclosure as set forth herein. 
     Example 1. The Use of Asfotase Alfa to Promote Mineralization after Spinal Fusion for Dystrophic Scoliosis in a Patient with Neurofibromatosis Type 1 (NF1) 
     Dystrophic scoliosis is a rare, but serious, skeletal manifestation in patients with neurofibromatosis type 1 (NF1) and may be associated with debilitating neurological impairment. Dystrophic curves progress rapidly and require early fusion, which is often complicated by poor bone healing and pseudoarthrosis. Poor bone healing in NF1 is thought to be due to a combination of reduced bone healing, increased bone resorption, and poor bone mineralization. Loss of neurofibromin can upregulate genes that promote pyrophosphate (PPi) synthesis, leading to PPi accumulation and inhibition of mineralization, impaired osteoblast differentiation with reduced alkaline phosphatase expression, and increased bone resorption. 
     Pre-clinical studies in mouse knock-out models of NF1 showed a decrease in the expression of Enpp1 and Ank, two main genes controlling PPi homeostasis. This result, however, was inconsistent with a reported human cell assay in adherent bone marrow cells (De la Croix Ndong, J., et al.,  Nature Medicine;  20: 904-910, 2014). 
     In this study, a 54-year-old post-menopausal woman with severe NF1-related dystrophic scoliosis and osteoporosis underwent three prior back surgeries over a period of 7 years, including prior T11 to pelvis spinal fusion ( FIG. 1 ). The spinal fusion was complicated by advanced dural ectasia ( FIG. 2 ), pseudoarthrosis, and life-threatening hemorrhage. An anterior approach was attempted, but was aborted due to left iliac vein complications. The patient also received posterior instrumentation and augmentation revision with bone morphogenetic proteins (BMPs), but continued to have progressive loosening of the screws, paresthesia of anterior thighs, and intractable back pain. She developed displacement of the rod at the L4 pedicle, requiring repeat surgery. The patient was also was taking 5 mg of morphine to help with the intractable back pain. The patient was managed conservatively with morphine treatment; however, back pain persisted with visual analog scale (VAS) pain score of 9 and Oswestry low back disability score of 52%. A CT scan revealed advanced peripheral lucency of the left posterior iliac screw, indicative of loosening ( FIG. 3A ) and a fracture of the left vertical rod at the L4 pedicle screw connection ( FIG. 3B ), necessitating a fourth spinal surgery. 
     Given a high probability of implant failure and difficulty in achieving solid arthrodesis after surgery, a decision was made to combine surgical intervention with additional available medical interventions including bone morphogenetic proteins (recombinant human BMP-2) to enhance bone healing, bisphosphonates (e.g., zoledronic acid) to inhibit bone resorption, and asfotase alfa (recombinant human alkaline phosphatase) to improve bone mineralization to achieve solid arthrodesis. 
     At the start of the study, the patient underwent a revision of lumbar fusion including reinsertion of spinal instrumentation of thoracic spine T11 to sacrum, reinsertion of pelvic fixation and posterior spinal fusion from T11 to pelvis ( FIG. 4 ). This was her fourth spinal surgery. Medical intervention during and after the repeat surgery included intrasurgical BMPs applied directly to the bone being operated on in order to enhance bone healing. 
     Approximately 3 months after surgery, to inhibit bone resorption, the patient received bisphosphonate therapy as a single 5 mg intravenous infusion of zoledronic acid without side effects. 
     Approximately 7 months after surgery and continuing for a 6 month period, asfotase alfa (recombinant human alkaline phosphatase, STRENSIQ®, Alexion Pharmaceuticals, Inc.) was administered subcutaneously at a dose of 2 mg/kg 3×/week to improve bone mineralization. Administration of asfotase alfa was discontinued at the end of six months (i.e., 13 months post-surgery). The patient did not experience serious adverse events during the treatment. 
     Solid arthrodesis was successfully obtained 13 months after this fourth surgery. Stable instrumented spinal fusion, as determined by CT scan (spinal radiograph) was observed at 13 months. No substantial change in overall bone mineral density was seen at that time, with T10 vertebral body as a reference point, using Hounsfield unit scale measurement. 
     BMPs alone (used to enhance bone formation) did not result in successful spinal fusion in this patient during earlier surgeries. They were used again during the patient surgery, but this time alongside combination therapy with a bisphosphonate and asfotase alfa. It was found that asfotase alfa in combination with BMPs (e.g., rhBMP-2) and bisphosphonate resulted in solid arthrodesis after spinal surgery in a patient with NF1-related dystrophic scoliosis, where BMP therapy alone had previously failed. 
     It was noted that markers of bone resorption increased after surgery. Following administration of the bisphosphonate zolendronic acid (ZOL) three months after surgery, bone resorption markers (NTX and CTX) decreased, but so also did bone formation markers (OCN and P1NP). Without being bound by theory, a decrease in these markers may be due to reduced bone turnover after ZOL. Consequently, the patient may experience inhibition of bone mineralization due to both the underlying disease and the use of ZOL (which otherwise has the beneficial effect of inhibiting bone resorption). 
     Meanwhile, however, both bone-specific alkaline phosphatase (BSAP) and total ALP levels increased significantly after administration of asfotase alfa. The study results suggest that administration of asfotase alfa following administration of a bisphosphonate such as ZOL can improve bone mineralization, somewhat like a “rescue” therapy. Administration of asfotase alfa was shown to improve bone mineralization despite the potentially confounding effects of administration of ZOL: fracture healing occurred, and loosening of the screws showed signs of resolution. These results suggest a more general treatment protocol that employs asfotase alfa as an adjunct to bisphosphonate therapy. More particularly, administration of bisphosphonates such as ZOL to inhibit bone resorption can be followed by administration of asfotase alfa to counteract possible adverse effects on bone mineralization of the bisphosphonate. This is in contrast to prevailing standard of care, which suggests that bisphosphonate treatment is contraindicated during asfotase alfa treatment (Kishnani, P., et al.,  Mol. Gen. Metab.  122:4-17, 2017). 
     Study Details 
     Table 2 summarizes laboratory and radiological investigations performed during the study&#39;s period, including reference ranges. The timing of all procedures was approximate, with specific date flexibility allowed based on the clinical progress of the patient, and to accommodate patient&#39;s schedule. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Laboratory and Radiological Investigations during Study Period 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                   
                   
                   
                 1.2 
               
               
                   
                   
                   
                   
                   
                   
                   
                 8 mo. 
                 yr after 
               
               
                   
                   
                   
                   
                   
                   
                   
                 after 
                 surgery 
               
               
                   
                   
                   
                   
                   
                   
                   
                 surgery 
                 6  
               
               
                   
                   
                   
                   
                   
                   
                   
                 1 month 
                 months 
               
               
                   
                 Baseline 
                   
                 ~5 
                 3 
                 4-7  
                   
                 after 
                 after 
               
               
                   
                 (before 
                   
                 days 
                 mo. 
                 mo.  
                   
                 starting 
                 starting 
               
               
                   
                 surgery as 
                   
                 after 
                 after  
                 after 
                   
                 asfotase 
                 asfotase 
               
               
                   
                 noted) 
                   
                 surgery 
                 surgery 
                 surgery 
                   
                 alfa 
                 alfa 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Creatinine 
                 0.63 
                 Surgery 
                 0.38 
                 0.58 
                   
                 Asfotase 
                 0.63 
                 0.68 
               
               
                 (0.52-1.04 mg/dl) 
                   
                   
                   
                   
                   
                 alfa 
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                 started 
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                 7 months 
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                 after 
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                 surgery 
                   
                   
               
               
                 25-0H Vitamin D 
                 67 
                   
                   
                 94 
                   
                   
                 43 
                 42 
               
               
                 (20-75 ug/L) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Total calcium (8.5- 
                 8.5 
                   
                 8.4 
                 9.0 
                   
                   
                 8.8 
                 8.7 
               
               
                 10.1 mg/dl) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Parathyroid hormone 
                 37 
                   
                   
                 73 
                   
                   
                 65 
                 66 
               
               
                 (12-72 pg/ml) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Alkaline 
                 58 
                   
                 86 
                   
                   
                   
                 &gt;2330 
                 &gt;2330 
               
               
                 phosphatase (40- 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 150 U/L) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Bone specific 
                 12.3 
                   
                   
                 19.1 
                   
                   
                 1949.5 
                 1751.1 
               
               
                 alkaline 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 phosphatase 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (postmenopausal 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 woman: 7-22.4 ug/L) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Osteocalcin 
                 26 
                   
                 20 
                 31 
                   
                   
                 10 
                 17 
               
               
                 (11-50 ng/ml) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Procollagen type 1 
                 83 
                   
                 87 
                 120 
                   
                   
                 43 
                 54 
               
               
                 intact N terminal Pro 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (P1NP) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (postmenopausal 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 woman: 16-96 ug/L) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 C-Telopeptide (CTx) 
                 721 
                   
                 844 
                 1256 
                   
                   
                   
                 559 
               
               
                 (postmenopausal 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 woman: 104-1008 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 pg/ml) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 N-Telopeptide (NTx) 
                 15.6 
                   
                 17.9 
                 25.5 
                   
                   
                 10.6 
                 14.4 
               
               
                 (postmenopausal 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 woman: 6.2-19 nM 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 BCE) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Serum inorganic 
                 1.11 
                   
                   
                   
                   
                   
                 2.3 
                   
               
               
                 pyrophosphate (PPi) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (1.00-5.82 μM) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Serum pyridoxal 5′- 
                 4.32 
                   
                   
                   
                   
                   
                 4.7 
                   
               
               
                 phosphate (PLP; 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 vitamin B6) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 (2.81-26.7 ng/ml) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Vitamin B6 
                 17.9 
                   
                   
                   
                   
                   
                 2.7 
                 &lt;2 
               
               
                 (20.0- 125.0 nmol/L) 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 using quantitative 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 HPLC 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 http://ltd.aruplab.com/ 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Tests/Pub/0080111 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 DXA scan 
                 3 mo prior 
                   
                   
                   
                   
                   
                   
                 x 
               
               
                 Spine x-ray 
                 7 mo prior 
                   
                 x 
                 x 
                 x 
                   
                   
                 x 
               
               
                 Spine CT 
                 7 mo prior 
                   
                 x 
                   
                   
                   
                   
                 x 
               
               
                 Orthopedic visit with 
                 2 mo prior 
                   
                   
                 x 
                 x 
                   
                   
                 x 
               
               
                 neurological exam 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Endocrine visit 
                 2 mo prior 
                   
                   
                 x 
                 x 
                   
                 x 
                 x 
               
               
                 Zoledronic acid 
                   
                   
                   
                 x 
                   
                   
                   
                   
               
               
                 Eye examination 
                   
                   
                   
                   
                 x 
                   
                   
                 x 
               
               
                 Renal ultrasound 
                   
                   
                   
                   
                 x 
                   
                   
                 x 
               
               
                   
               
            
           
         
       
     
     Pre-Asfotase Alfa Treatment Investigations 
     Report of a Renal Ultrasound Four Months after Surgery 
     Right kidney 9.7 cm, normal echotexture and cortex. No mass, stones or hydronephrosis Left kidney 10.4 cm, normal echotexture and cortex. No mass, stones or hydronephrosis 
     Comprehensive eye exam on 5 months after surgery reported as keratoconjunctivitis sicca especially left eye as seen by eyelid anomaly temporally. Normal oculomotor nerve. Normal macula. 
     Baseline DXA scan revealed the left femoral neck BMD 0.643 which corresponded to T-score of −2.8. The right femoral neck BMD was 0.627 which corresponded to T-score of −3.0. Mean total hip BMD 0.635 which corresponded to T-score of −2.9. Compared to BMD in 8 years earlier, bone density decreased 8.1% which was significant. Left 33% forearm BMD 0.621 which corresponded to T-score of −3.0. 
     Radiographic Data, CT Lumbar Spine 
     Preoperative CT and spinal radiograph obtained 7 months prior to surgery showed fracture of the left vertical connecting rod below left L4 pedicle screw and peripheral lucency of the left posterior iliac spine screw ( FIGS. 3A-3B ). Advanced dural ectasia of lumbar spine, particularly the right L2-L4, and postsurgical change of the spine pelvis fusion instrumentation from T 11 to pelvis with bilateral sacroiliac joints screws were noted. 
     The date of the surgery, a revision of lumbar fusion including reinsertion of spinal instrumentation of thoracic spine T11 to sacrum, reinsertion of pelvic fixation and posterior spinal fusion from T11 to pelvis were performed ( FIG. 4 ). 
     Immediate postoperative CT and spinal radiograph obtained 2 days after surgery due to sudden onset of stocking-like paresthesia of bilateral ankles without weakness showed post-surgical changes of revision instrumented spinal fusion T11-pelvis with additional screws extending into the medial iliac bones bilaterally. Bilateral pedicle screws at T11, T12, L1, S1, left pedicle screw at L2 and L4, right pedicle screw at L5, and bilateral iliac screws were noted. Stable lucency around the left posterior iliac screw was seen with a new bony defect in the outer cortex at the tip of the screw ( FIGS. 5A-5B ). Paresthesia of bilateral ankles improved gradually 2 days later, and the patient ambulated safely prior to discharge home. Given patient&#39;s severe dystrophic scoliosis and previous high probability of failing given past surgical history of mechanical failing, the patient also received zoledronic acid to inhibit bone resorption (5 mg IV at 3 months after surgery one time) to inhibit bone resorption and asfotase alfa to improve bone mineralization (2 mg/kg 3×/week subcutaneous injection) from 7 to 13 months after surgery) to improve bone mineralization. 
     Spinal radiograph obtained 3 month and 7 months after surgery showed stable postsurgical changes of spinal fusion, with intact instrumentation noted posteriorly from T11 through the sacrum, with screws extending across both sacroiliac joints, i.e., stable instrumented spinal fusion T11-pelvis with solid bilateral dorsolateral ankyloses were observed. Healing and sclerosis of the previously seen bony defect associated with the tip of the left posterior iliac screw was observed since the two days after surgery observation. 
     Post Asfotase Alfa Treatment Investigations 
     Radiograph 
     CT and spinal radiograph obtained approximately 7 months after asfotase alfa initiation showed stable instrumented spinal fusion T11-pelvis with solid bilateral dorsolateral ankylosis. Interval healing of left peri-screw iliac fracture was observed since 5 days after surgery. Minimal marginal lucency about the bilateral sacroiliac joint screws was observed without convincing evidence of loosening. Stable convex right scoliosis and asymmetric right dural ectasia were observed. 
     A repeat renal ultrasound, repeat eye exam, and repeat DXA scan were planned for 1.2 years after surgery. Renal ultrasound and comprehensive eye examination before and after asfotase alfa treatment revealed no ectopic calcification. On the follow-up visit at 13 months after surgery, patient reported an improvement in back pain with a VAS pain score of 7 and an Oswestry low back disability score of 42%. The patient was able to stop morphine treatment. 
     Additional Observations 
     In conclusion, stable instrumented spinal fusion was observed after surgery determined by spinal radiograph. In comparison to immediate postoperative CT lumbar spine (obtained 2 days after surgery) that showed lucency around the left posterior iliac screw (suggestive of screw loosening) with a new bony defect at the tip of the screw (indicative of peri-screw fracture), a CT lumbar spine approximately 6 months after asfotase alfa initiation showed healed fracture at the tip of the left posterior iliac screw without evidence of loosening ( FIG. 6 ). However, when compared between these 2 CT scans, there was no significant change in bone mineral density using CT Hounsfield measurement noted in T10 vertebral body as reference point where there was no surgical change. Degree of gross bony bridging (indicating bone formation) that was presented before the revisional surgery as well as objective measurement (HU measurement) at posterior element bony bridging sites showed no substantial interval change. 
     Example 2. Treatment of a Femoral Fracture 
     According to the methods disclosed herein, an orthopedic surgeon of skill in the art may treat a patient with a fractured femur. For example, the patient may have fractured her femur after falling off a bicycle or may have spontaneous fracture. The non-displaced fracture may cause intense pain and the doctor may perform an orthopedic surgery in which a plate and four screws are to be placed over the fracture, to be followed by immobilization of the patient&#39;s leg in a cast for three months. Following the three months, if the bone does not display adequate healing as viewed by X-ray and CT scan, or if the screws loosen, the orthopedic surgeon may treat the patient with a regimen of asfotase alfa administered subcutaneously at 6 mg/kg/week for two months. Following the asfotase alfa treatment, the doctor or surgeon may perform an additional X-ray and CT scan to visualize the healing process. The doctor or surgeon may determine that the asfotase alfa treatment has aided the healing process and the two screws are no longer loose. After sufficient healing, the surgeon may determine that the hardware, including the plate and four screws, may be removed from the femur. 
     Example 3. Treatment of Traumatic Facial Fracture 
     A patient with a multiply fractured facial cheek bone could be treated by an oral maxillofacial surgeon or plastic surgeon with reconstruction of the facial bones to restore the original shape and features of the face. Due to the complexity of the fractures, the surgeon may decide to utilize multiple screws and plates to aid in reformulation of the facial bones. The screws and plates may be designed to remain in the face permanently. The doctor may first initiate a regimen of asfotase alfa administered locally at 2 mg/kg/week for two weeks before surgery. The doctor may perform the surgery and place the plates and screws onto the fractured areas of the cheek bone. Following three months of recovery time, the doctor may visualize the healing process by X-ray and CT scan. The doctor may determine that one of the screws is loose, and the dosage of asfotase alfa could be increased to 6 mg/kg/week. Following another month of recovery time, the doctor may again visualize the healing process by X-ray and CT scan and may determine that the screw is no longer loose, at which time the asfotase alfa treatment may be terminated. 
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     The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The disclosure is not limited to the exact details shown and described, for variations apparent to one skilled in the art will be included within the disclosure defined by the claims. 
     Unless otherwise indicated, all numbers expressing quantities of components, molecular weights, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless otherwise indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by the disclosure. At the very least, and not as an attempt to limit the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. All numerical values, however, inherently contain a range necessarily resulting from the standard deviation found in their respective testing measurements. 
     All headings are for the convenience of the reader and should not be used to limit the meaning of the text that follows the heading, unless so specified. 
     The complete disclosures of all patents, patent applications including provisional patent applications, publications including patent publications and nonpatent publications, and electronically available material (including, for example, nucleotide sequence submissions in, e.g., GenBank and RefSeq, and amino acid sequence submissions in, e.g., SwissProt, PIR, PRF, PDB, and translations from annotated coding regions in GenBank and RefSeq) cited herein are incorporated by reference.