LY09 Disease status at haematopoietic stem cell transplantation, including skin-limited disease, and survival in blastic plasmacytoid dendritic cell neoplasm: a retrospective, multicentre cohort study of the European Organisation for Research and Tre

Abstract

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, aggressive haematological malignancy commonly involving the skin. Haematopoietic stem cell transplantation (HSCT) is the only potentially curative treatment, yet the prognostic relevance of skin-limited disease and disease status at HSCT remains unclear. We aimed to evaluate the association between HSCT and survival in BPDCN, and to assess whether disease status at transplantation provides prognostically relevant information. We performed a retrospective multicentre cohort study across 10 European tertiary centres. Patients diagnosed with BPDCN from 2008 onward were included. Overall survival was analysed using Kaplan–Meier methods and Cox regression, with HSCT modelled as a time-­dependent covariate to account for immortal time bias. Post-transplant survival was assessed according to disease status at HSCT. Forty-seven patients were included (median age 60 years, 74% male), of whom 26 (55%) underwent HSCT. In time-­dependent Cox analysis, HSCT was strongly associated with improved overall survival (adjusted hazard ratio 0.17, 95% confidence interval 0.05–0.55; P = 0.003). Among transplanted patients, those transplanted in complete remission or with skin-limited residual disease tended to have better post-transplant outcomes than those with active systemic disease. In this pan-European real-world cohort, HSCT was associated with improved survival in BPDCN when analysed using a time-dependent approach. Disease status at the time of transplantation, rather than initial disease presentation, appears to provide clinically relevant prognostic information and supports the importance of achieving deep remission before HSCT whenever feasible.