Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is incurable with conventional therapies. Limited retrospective data have shown durable remissions after haematopoietic cell transplantation (HCT) [allogeneic (allo) or autologous (auto)]. We conducted a multicentre retrospective study in BPDCN patients treated with allo-HCT and auto-HCT at 8 centres in the United States and Canada. Primary endpoint was overall survival (OS). The population consisted of 45 consecutive patients who received an allo-HCT (n = 37) or an auto-HCT (n = 8) regardless of age, pre-transplant therapies, or remission status at transplantation. Allo-HCT recipients were younger (50 (14-74) vs. 67 (45-72) years, P = 0·01) and had 1-year and 3-year OS of 68% [95% confidence interval (CI) = 49-81%] and 58% (95% CI = 38-75%), respectively. Allo-HCT in first complete remission (CR1) yielded superior 3-year OS (versus not in CR1) [74% (95% CI = 48-89%) vs. 0, P < 0·0001]. Allo-HCT outcomes were not impacted by regimen intensity [3-year OS for myeloablative conditioning = 61% (95% CI = 28-83%) vs. reduced-intensity conditioning = 55% (95% CI = 28-76%)]. One-year OS for auto-HCT recipients was 11% (95% CI = 8-50%). These results demonstrate efficacy of allo-HCT in BPDCN, especially in patients in CR1. Pertaining to auto-HCT, our results suggest lack of efficacy against BPDCN, but this observation is limited by the small sample size. Larger prospective studies are needed to better define the role of HCT in BPDCN.

Complete response rates appear higher when DLI is used for relapsed CLL and lymphomas (NHL and HL), and less pronounced in ALL or MM. Absence of data pertaining to disease-specific prognostic determinants, such as adverse genetic or molecular abnormalities, or quantitative disease burden when applicable, limit our ability to identify cases in whom benefits from DLI outweigh risks associated with the procedure within a particular disease.

The advent of novel immunotherapy and tyrosine kinase inhibitors has ushered a new era in the treatment of Hodgkin and non-Hodgkin lymphomas. Allogeneic hematopoietic cell transplantation remains, however, a vital component in the management and potential cure of lymphomas, especially in the relapsed setting. Considering the biological and clinical heterogeneity of various subtypes of lymphomas, the optimal intensity of conditioning regimens remains controversial. Reduced intensity conditioning regimens have broadened applicability of the procedure to older and frail patients. Observational studies suggest that although reduced intensity allografting is associated with higher risk of relapse, overall survival is comparable and in some cases even better, than observed with myeloablative regimens. Here, we review the available published data pertaining to allogeneic hematopoietic cell transplantation using reduced intensity or myeloablative conditioning for various lymphoma histologies. Owing to the lack of randomized prospective trials, recommendations are mainly based on registry and single-institution studies. Special emphasis must be given to implementing strategies to prevent relapse when using reduced intensity regimens. Identifying particular patients who may benefit from myeloablative regimens in lymphomas remains to be better defined.