Ab1372 Pediatric Autologous Hematopoietic Stem Cell Transplantation in Treatment-Resistant Autoimmune Diseases: A Real-Life Single-Center Experience

Background: In recent years, advances have been made in the treatment of severe autoimmune and inflammatory diseases in pediatric patients. However, some patients still experience persistent or recurrent disease activity. Autologous Hematopoietic Stem Cell Transplantation (AHSCT) is used as a therapeutic approach in such cases since more than two decades. However, there is limited data specifically from pediatric patients. Objectives: The primary objective is efficacy as measured by treatment response, PFS (Progression Free Survival) and OS (Overall survival). The secondary objectives are safety; infectious and non-infectious adverse events within 2 years after AHSCT and disease status at long-term follow-up. Methods: This retrospective, non-interventional study presents outcome data from 7 consecutive pediatric patients (2 systemic sclerosis, 1 pan-sclerosis, 2 systemic juvenile idiopathic arthritis, 1 dermatomyositis, 1 eosinophilic fasciitis) who underwent AHSCT for treatment-resistant autoimmune diseases at the Tübingen Center for Pediatric Rheumatology and Autoinflammatory Diseases between 1999 and 2021. Results: The median age of patients at the time of AHSCT was 10 years (IQR 8-17). The median follow-up duration was 17 years (IQR 14-21 years). Median PFS was 3 years (95% CI: 0.43-5.5). Median OS was 17 years (95% CI: 11.8-22.1). At 1 and 2 years after AHSCT, PFS rates were 100% and 77% (95% CI: 54-88), respectively, and overall survival rate was 100%. No serious infectious complications were observed except for one patient with an infection leading to SIRS and requiring intensive care therapy. 3 patients developed secondary autoimmune diseases (1 MAS, 1 Graves' disease, 1 autoimmune hemolytic anemia), 1 patient had fibroadenoma on routine screening during follow-up, 1 patient experienced deterioration in renal parameters and pericardial effusion thought to be due to cyclophosphamide but resolved spontaneously after discontinuation of treatment. One patient developed amenorrhea after transplantation. Today, all patients are still alive and 4/7 are in clinical remission on medication, 3/7 in clinical remission off medication. Conclusion: AHSCT is effective in the treatment of severe auto-immune syndromes in children and may be considered as a treatment option. Data on the pediatric patient population are limited, so more data are needed on the long-term efficacy and safety of transplantation. The indication and timing of transplantation requires a multidisciplinary approach. REFERENCES: [1] Alexander, T., et al., [Autologous hematopoietic stem cell transplantation for autoimmune diseases: Current indications and mode of action, a review on behalf of the EBMT Autoimmune Diseases Working Party (ADWP)]. Z Rheumatol, 2020. 79(5): p. 419-428. [2] Tyndall, A. and A. Gratwohl, Haemopoietic stem and progenitor cells in the treatment of severe autoimmune diseases. Ann Rheum Dis, 1996. 55(3): p. 149-51. [3] Tsukamoto, H., et al., A phase I-II trial of autologous peripheral blood stem cell transplantation in the treatment of refractory autoimmune disease. Ann Rheum Dis, 2006. 65(4): p. 508-14. [4] Alexander, T., R. Greco, and J.A. Snowden, Hematopoietic Stem Cell Transplantation for Autoimmune Disease. Annu Rev Med, 2021. 72: p. 215-228. Acknowledgements: NIL. Disclosure of Interests: None declared.