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Blastic plasmacytoid dendritic cell neoplasm (BPDCN), previously known as natural killer (NK) cell leukemia/lymphoma, is categorized by the World Health Organization (4th edition, 2008) under acute myeloid leukemia (AML). Most often, BPDCN presents with features of both lymphoma and leukemia. There are little data about BPDCN and there is no established treatment. The average age at diagnosis is 60 to 70 years. There are more men than women who are diagnosed with BPDCN.
Diagnosis and Incidence
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is very often misdiagnosed and under-reported. Diagnosing a patient with BPDCN is difficult.
The skin is the most frequently involved site of disease (80 percent of cases). However, BPDCN usually progresses with bone marrow involvement and a decrease in red blood cell, white blood cell and platelet counts. The lymph nodes and spleen may also be involved. Rashes without symptoms can also occur.
Common misdiagnoses for BPCDN include non-Hodgkin lymphoma (NHL), acute myeloid leukemia (AML), leukemia cutis (a nonspecific term used for cutaneous [skin] manifestation of any type of leukemia), melanoma (a type of skin cancer), and lupus erythematosus (chronic inflammatory disease that occurs when your body's immune system attacks your own tissues and organs).
Current Treatment and Outcomes
There are no data or clinical trials that can define the best first treatment for patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN).
Treatment sometimes includes therapies that are used for AML, acute lymphoblastic leukemia (ALL), or lymphoma.
The length for which a patient responds to these treatments is usually short. After a relapse, second remissions with conventional chemotherapy are difficult to achieve. Allogeneic hematopoietic stem cell transplant (allo-HCT), especially if offered in first remission, may result in longer remissions. The current recommendation is for BPDCN patients to be evaluated for an allo-HCT as soon as possible and to begin searching for a donor.
Research and Evolving Novel Treatments
Because the current treatments do not result in long term remission, patients need to consider clinical trials for new therapies. There are numerous therapies currently in clinical trials, including SL-401 and IMGN 632.
SL-401 is a novel biologic targeted therapy and has shown significant antitumor effects. Improvement in long-term outcomes is expected. There have been multiple complete responses (CRs) in patients with relapsed or refractory BPDCN and AML after a single cycle of the drug as a single agent in prior Phase I/II clinical trials. A new trial "SL-401 in Patients with Blastic Plasmacytoid Dendritic Cell Neoplasm or Acute Myeloid Leukemia" is now open for enrollment.
IMGN632 is an antibody drug conjugate that targets CD123 positive malignancies including BPDCN, AML and ALL. A new Phase 1 trial of IMGN632 is now open for enrollment.