Hematopoietic cell transplantation for blastic plasmacytoid dendritic cell neoplasm: clinical practice guidelines from the American Society for Transplantation and Cellular Therapy.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive hematologic malignancy with complex clinical manifestations, frequently involving multiple organs. Treatment of BPDCN has evolved over the years from conventional chemotherapy to novel targeted therapies including anti-CD123 antibody drug conjugates, namely tagraxofusp and pivekimab sunirine, and the BCL-2 inhibitor, namely venetoclax. However, because anticipated long term disease control is not generally possible, it is standard practice to offer allogeneic hematopoietic cell transplantation (HCT) as a consolidation strategy for eligible patients. No HCT societal guidelines exist to guide contemporary clinical practice of HCT in patients with BPDCN. A panel of 17 experts, including one representative of community practice, was convened to develop relevant guidelines and followed the Grading of Recommendations, Assessment, Development and Evaluation methodology. For BPDCN in first complete remission (CR1), the panelists recommended allogeneic HCT and suggested autologous HCT for patients who are unfit for allogeneic HCT but without BPDCN marrow involvement. Acknowledging that some patients might not have received either allogeneic or autologous HCT in CR1, panelists voted similarly for patients in second CR (CR2). Conversely, the panelists did not recommend allogeneic or autologous HCT in BPDCN after primary induction failure or with active relapsed-refractory disease. The panel recommended that conditioning intensity for younger fitter patients be myeloablative, preferentially containing total body irradiation, whereas reduced intensity conditioning was recommended for older and/or frail ones, in both CR1 or CR2. Post-HCT intrathecal chemotherapy was also recommended regardless of involvement of the central nervous system. Panelists recognized that other unique clinical scenarios not included in these recommendations might demand individualized treatment approaches.