Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy. It was initially regarded as a form of lymphocyte-derived cutaneous  lymphoma and alternatively named CD4+CD56+ hematodermic tumor, blastic NK cell lymphoma, and agranular CD4+ NK cell leukemia. Later, however, the disease was determined to be a malignancy of plasmacytoid dendritic cells rather than lymphocytes and therefore termed blastic plasmacytoid dendritic cell neoplasm. In 2016, the World Health Organization designated BPDCN to be in its own separate category within the myeloid class of neoplasms. It is estimated that BPDCN  constitutes 0.44% of all hematological malignancies.Blastic plasmacytoid dendritic cell neoplasm is an aggressive malignancy with features of cutaneous lymphoma (e.g. malignant plasmacytoid dendritic cell infiltrations into the skin to form single or multiple lesions) and/or leukemia (i.e. malignant plasmacytoid dendritic cells in blood and bone marrow). While commonly presenting with these clinical features, BPDCN, particularly in its more advanced stages, may also involve  malignant plasmacytoid dendritic cell infiltrations in and thereby injury to the liver, spleen, lymph nodes, central nervous system, or other tissues. The neoplasm occurs in individuals of all ages but predominates in the elderly; in children, it afflicts males and females equally but in adults is far more common (~75% of cases) in males.Blastic plasmacytoid dendritic cell neoplasm typically responds to chemotherapy regimens used to treat hematological malignancies. All too often, however, the disease rapidly recurs and does so in a more drug-resistant form.
A phase I clinical research study to test the safety and efficacy of a combination chemotherapy regimen consisting of methotrexate, L-asparaginase, idarubicin, and dexamethasone followed by allogenic or autologous bone marrow transplantation in 26 participants newly diagnosed with BPDCN is planned but not yet in its recruiting phase.While few studies have reported on the treatment of BPDCN that has recurred following initial therapy, donor lymphocyte infusions coupled with alternative chemotherapy treatments have induced second complete or partial remissions in a few patients. Tagraxofusp-erzs
Tagraxofusp-erzs (trade name Elzonris; formerly SL-401 and DT388-IL3) was approved in the United States in December 2018 for the treatment of BPDCN. Tagraxofusp-erzs is a fusion protein consisting of interleukin 3 (i.e. IL-3) fused to diphtheria toxin. The fusion protein readily kills cultured pDC by binding to their IL-3 receptors to thereby gain entrance to the cells and then blocking these cells protein synthesis (due to diphtheria toxin-mediated inhibition of eukaryotic elongation factor 2). Prognosis
Due to the high rates of recurrence following initial therapy and the short overall survival times of individuals with BPDCN, prognosis of the disease is poor. However, further study of treatment regimens that include intrathecal chemotherapy and hematological stem cell transplantation in initial treatment regimens (see previous section) and newer non-chemotherapeutic drug treatments (see next section) may improve this situation. Research
UCART123
UCART123 are chimeric T cell receptor-bearing cells, i.e. T lymphocytes engineered to bear a monoclonal antibody that directs them to attack and kill BPDCN cells.