Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy originating from precursor plasmacytoid dendritic cells. Accounting for less than 1% of all hematologic cancers, BPDCN is characterized by the expression of markers such as CD4, CD56, and CD123 (interleukin-3 receptor α)

 

Clinically, BPDCN often presents with skin lesions—nodules, plaques, or bruise-like discolorations—that may be accompanied by systemic involvement, including bone marrow infiltration, lymphadenopathy, and splenomegaly. Without prompt treatment, the disease progresses rapidly, with a historically poor prognosis and median survival ranging from 8 to 14 months .

 

A significant advancement in BPDCN treatment is the FDA-approved therapy Elzonris (tagraxofusp-erzs), a CD123-directed cytotoxin. Elzonris is a recombinant fusion protein combining interleukin-3 with a truncated diphtheria toxin, targeting CD123-expressing malignant cells to induce apoptosis.

 

Clinical trials have demonstrated Elzonris’s efficacy in both treatment-naïve and relapsed/refractory BPDCN patients. In a pivotal study, the therapy achieved a high overall response rate, including complete responses, particularly in patients treated during earlier disease stages . However, Elzonris administration requires careful monitoring due to potential toxicities, such as capillary leak syndrome (CLS), which can be life-threatening if not promptly managed.

 

Elzonris represents a significant advancement in BPDCN treatment, offering a targeted approach for a disease with limited therapeutic options. Ongoing research is exploring its use in combination with other therapies and its potential applications in other CD123-positive malignancies.