Autologous hematopoietic stem cell transplantation with reduced-intensity conditioning regimens in refractory Takayasu arteritis: a retrospective multicenter case-series from the Autoimmune Diseases Working Party (ADWP) of the European Society for Blood and Marrow Transplantation (EBMT).

Autologous hematopoietic stem cell transplantation (AHSCT) has emerged as a promising treatment option in severely affected and refractory patients with autoimmune diseases. This is a retrospective survey of patients reported to the EBMT registry between 1998 and 2019, who received AHSCT for TAK. Data from six patients treated with AHSCT for refractory TAK have been identified, five were female (83%), median age 25 (9-39) years. All patients were pretreated with a median of 6 (4-8) lines of therapy, including steroids (six patients), methotrexate (five patients), cyclophosphamide, mycophenolate mofetil or infliximab (four patients), tocilizumab or etanercept (two patients). Conditioning included cyclophosphamide and rabbit anti-thymocyte globulin in all patients. At 6 months post transplantation, remission was obtained in all cases, which persisted at 12 months in five cases. Four patients reactivated TAK at a median time of 27 (7-52) months after AHSCT, and three resumed disease-modifying therapy. At last follow-up, all patients were alive, two patients were in remission (off-therapy), two patients improved compared with baseline, and two patients were in complete and partial remission, respectively, under immunosuppressive treatment. This retrospective case-series demonstrates that AHSCT has the potential to provide significant clinical responses in TAK patients, but large prospective trials are necessary to confirm these preliminary data.