Efficacy of venetoclax combined with azacitidine for advanced blastic plasmacytoid dendritic cell neoplasm: experience from two Japanese cases

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy with no established standard treatment. Recently, the combination of venetoclax (VEN) and azacitidine (Aza) has shown promising efficacy in elderly or unfit patients; however, clinical data in Japanese patients remain limited. We report two Japanese cases with BPDCN that responded favorably to VEN plus Aza therapy. The first case involved a 50-year-old man who relapsed shortly after Hyper-CVAD/MA therapy with leukemic transformation. Despite requiring dose reductions due to prolonged cytopenia and infections, he achieved a complete response after eight cycles of VEN plus Aza. The second case was an 81-year-old man with widespread skin and bone marrow lesions. He showed a marked clinical response after only 7 days of treatment, although therapy was discontinued due to COVID-19 infection. Both cases demonstrate that VEN plus Aza therapy can induce rapid and clinically meaningful responses even in short or attenuated regimens in patients with refractory or elderly BPDCN. However, cytopenias and infections are significant limitations, warranting that individualized dosing may be necessary depending on patient characteristics, including ethnicity and body size. Our findings support the consideration of VEN plus Aza as a feasible therapeutic option for patients with BPDCN.