Late complications after autologous HSCT for autoimmune diseases: a retrospective survey from the autoimmune diseases working party (ADWP), transplant complications working party (TCWP) and paediatric diseases working party (PDWP) of the european society for blood and marrow transplantation (EBMT)

Autologous hematopoietic stem cell transplantation (aHSCT) has evolved as a treatment for severe autoimmune diseases (ADs). Advances in transplant procedures and supportive care have led to improvements in long-term survival but there is limited data on 'late effects'. The aim of this retrospective EBMT registry study is to assess the incidence of 'late effects' after aHSCT for ADs. All EBMT centres were invited and data were received for 579 patients (median age 37 years, range 2.7-73.8), who received aHSCT between 1997 and 2016. Median follow-up was 89 months (IQR 82.4-95.5). Indications included multiple sclerosis (MS, 46.8%), systemic sclerosis (SSc, 28.7%), Crohn's disease (CD, 12.6%), systemic lupus erythematosus (SLE, 2.4%) and other ADs (9.5%). Conditioning was mainly based on Cy/ATG (51.9%) or BEAM/ATG (25.3%). At 10-years, the cumulative incidence of secondary ADs was 10.3% (95% CI: 7.7-13.3), new post-transplant cancers 4.1% (95% CI: 2.2-6.8), endocrine complications 16.2% (95% CI: 12.6-20.1), and cardiovascular complications 14.7% (95% CI: 11.2-18.6). Median time to endocrine events (15.4 months) was generally sooner than median times to secondary ADs (24.5 months) and cardiovascular (25.3 months), with new cancers occurring relatively late (median time 81.7 months). Overall, at 10-years, progression-free survival (PFS) was 40.1% (95% CI: 34.7-45.4), overall survival (OS) 83.5% (95% CI: 79.3-86.9) and non-relapse mortality (NRM) 5.0% (95% CI: 3.2-7.4). By multivariate analysis, secondary ADs were relatively higher in CD vs SSc (HR = 4.93, p = 0.01) and MS (HR = 2.05, p = 0.055), while cardiovascular complications were significantly increased in SSc compared to MS (HR = 8.85, p < 10-3) or CD (HR = 3.45, p = 0.016). The incidence of post-aHSCT cancers was related to increasing age (HR per 10 y = 2.26, p < 10-3), without significant association with disease type. Incidence of endocrine complications were significantly lower in SSc compared to MS (HR = 0.35, p = 0.027) and CD (HR = 0.33, p = 0.041) and significantly more frequent in females (HR = 4.27, p < 10-3). Autologous HSCT for ADs is associated with a cumulative burden of non-infectious late complications, including thyroid dysfunction, osteoporosis, cardiovascular complications, gonadal dysfunction, secondary ADs and subsequent cancers. These impact all ages of patient and vary depending on AD indication, reflecting disease characteristics and other treatments. This study highlights the importance of screening, monitoring, and treatment of late effects in this setting.