Kidney Week

Abstract: FR-PO1124

Proactive Perioperative Recombinant ADAMTS13 Enables Kidney Transplantation in Congenital Thrombotic Thrombocytopenic Purpura

Session Information

• Transplantation: Clinical - Transplant Access, Recipient Evaluation, Living Donors, Pregnancy, and More
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Transplantation

• 2002 Transplantation: Clinical

Authors

• Peixoto, Daniela Filipe, Unidade Local de Saude de Santo Antonio EPE, Porto, Porto District, Portugal

Daniela Filipe Peixoto, MD

• Reis Pereira, Pedro Manuel, Unidade Local de Saude de Santo Antonio EPE, Porto, Porto District, Portugal

Pedro Manuel Reis Pereira, MD, PhD

• Fernandes, João Pimenta, Unidade Local de Saude de Santo Antonio EPE, Porto, Porto District, Portugal

João Pimenta Fernandes, MD

• Silvano, José Luís, Unidade Local de Saude de Santo Antonio EPE, Porto, Porto District, Portugal

José Luís Silvano, MD

• Martins, La Salete, Unidade Local de Saude de Santo Antonio EPE, Porto, Porto District, Portugal

La Salete Martins

• Do Santos, Josefina, Unidade Local de Saude de Santo Antonio EPE, Porto, Porto District, Portugal

Josefina Do Santos, PhD

Introduction

Congenital thrombotic thrombocytopenic purpura (cTTP) is caused by biallelic ADAMTS13 variants and may progress to end-stage kidney disease (ESKD). Kidney transplantation (KT) in cTTP is exceptional and historically managed with plasma therapy, with frequent graft losses. The only reported recombinant ADAMTS13-supported KT (Zethof, BMJ Case Rep 2025) introduced recombinant enzyme reactively, two years post-transplant, after three thrombotic microangiopathy (TMA) episodes on plasma exchange. We report the first KT performed under apadamtase alfa prophylaxis established before transplant, with proactive perioperative intensification.

Case Description

A 40-year-old woman has cTTP confirmed by a homozygous ADAMTS13 c.2074C>T variant (activity <1%, no inhibitor). Diagnosed at age 3, she was maintained on biweekly fresh-frozen plasma (FFP). In April 2013 a 24-week pregnancy was complicated by TMA with intrauterine fetal death, salvaged with plasma. Two ischaemic strokes followed (2020, 2021). She progressed to ESKD and started haemodialysis in May 2022. In March 2024 FFP was replaced by home-administered apadamtase alfa 2500 IU every two weeks, with complete TMA suppression. In March 2026 she underwent KT from a deceased donor (HLA mismatch 2/6, cPRA 78.6%). The perioperative protocol comprised daily intravenous apadamtase alfa 2500 IU with daily ADAMTS13 activity monitoring during admission, transitioning to weekly 2500 IU at discharge. Induction was with rabbit antithymocyte globulin (cumulative 6 mg/kg); maintenance comprised tacrolimus, mycophenolate mofetil 1 g/day, tapering prednisolone, and aspirin. At 2 months after KT the allograft is functioning with serum creatinine 0.93 mg/dL, ADAMTS13 activity trough 28%, and no evidence of TMA.

Discussion

Among prior cTTP kidney transplants, durable graft function has been reported only with plasma exchange plus eculizumab rescue (Fattah 2017) or with intensified FFP in a paediatric recipient (Khan 2025); other cases ended in graft loss within 1 to 23 months. To our knowledge this is the first kidney transplant performed under apadamtase alfa prophylaxis established before transplant, and the first proactive perioperative recombinant ADAMTS13 protocol. Apadamtase alfa may obviate plasma therapy in cTTP kidney transplant recipients.