SUN-734 Treatment Efficacy and Complications Associated with Asfotase alfa Therapy in Hypophosphatasia

Abstract Disclosure: A. Smoleva: None. S. Gundlapally: None. S. Patel: None. L. Mitchell: None. B. Wright: None. M. Antony: None. Introduction: Asfotase alfa is a human recombinant tissue-nonspecific alkaline phosphatase [TNSALP] enzyme replacement therapy approved for treating perinatal/infantile and juvenile-onset Hypophosphatasia [HPP]. We present a case of HPP who is currently receiving treatment with Asfotase alfa and we discuss the overall clinical course, treatment efficacy and complications associated with therapy. Clinical Case: A 36-year-old Caucasian female established care in the adult endocrinology clinic for long-term management of HPP with Asfotase alfa. Patient’s childhood history was pertinent for at least one low trauma fracture involving the right wrist at the age of 6 years, presence of multiple dental cavities which required multiple crown placements and chronic musculoskeletal pains with predominant involvement of the left big toe region. She underwent extensive evaluation over the years through multiple subspecialists to no avail. Eventually, In October 2022, patient underwent genetic testing based on clinical findings of low serum alkaline phosphatase and an elevated vitamin B6 level. Patient was found to have one pathogenic variant in the alkaline phosphatase [ALPL] gene, confirming the diagnosis of HPP. In August 2023, patient was initiated on a thrice weekly regimen of Asfotase alfa by endocrinology which led to a marginal improvement in her musculoskeletal pains. To help with further clinical improvement, the regimen was increased to six times per week which not only brought a relief in her resting pains but also improved her baseline activity level and exercise tolerance. In April 2024, patient underwent a comprehensive eye examination which did not reveal any signs of calcium build-up. Patient however has been experiencing injection site reaction in the form of pain but there is no clinical evidence of calcification or lipodystrophy. Most recent lab work-up from January 2025 revealed normal corrected calcium 9.0 mg/dl [8.6-10.0 mg/dl], mid normal vitamin D 62.7 ng/ml [30-100 ng/ml] and patient has been advised to continue asfotase alfa 1 mg per kg body wt x 6 times per week regimen. Conclusion: Asfotase alfa enzyme replacement therapy not only improves the clinical symptoms and quality of life but also may be beneficial in reducing the future risk of bone and teeth complications. Presentation: Sunday, July 13, 2025