New Human Leukocyte Antigen (HLA) Antibody Formation and Creatinine Elevation With Abaloparatide in Kidney Transplant Recipient.

A 39-year-old female with a history of kidney transplant presented to the endocrinology clinic for osteoporosis evaluation after sustaining an ankle fracture from a fall. Her kidney transplant regimen (mycophenolate mofetil 360 mg twice a day, tacrolimus 0.5 mg every morning and 0.5-1 mg every evening, prednisone 5 mg/day) and baseline creatinine (1.0-1.2 mg/dL) had been stable for several years. After an appropriate secondary workup, she was started on abaloparatide 80 μg subcutaneous daily injections for osteoporosis. She had a good initial biochemical response to therapy. However, 5 months after abaloparatide initiation she was found to have a new elevation in serum creatinine (1.17 to 1.69 mg/dL) despite stable serum tacrolimus trough levels, and two new human leukocyte antigen (HLA) antibodies (anti-HLA antibodies detected to Cw7 and DP28). Abaloparatide was stopped due to concern for immunogenicity. There was no evidence of rejection on kidney biopsy and she was restabilized on her transplant regimen with a new baseline creatinine of 1.3-1.6 mg/dL. The patient was subsequently started on teriparatide 20 μg daily subcutaneous injections for 2 years with good biochemical response, significant improvement in bone mineral density, and stable transplant regimen without additional signs of immunogenicity or rejection. This is the first case report to raise concern about immunogenicity with abaloparatide in solid organ transplant recipients. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.