Tagraxofusp followed by combined azacitidine and venetoclax in blastic plasmacytoid dendritic cell neoplasm: A case report and literature review.

Introduction: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy that originates from plasmacytoid dendritic cells. It can involve skin, bone marrow, and/or lymph nodes. There is no consensus recommendation regarding treatment especially in the relapsed setting. Tagraxofusp, a CD123 directed agent, was recently approved by the Food and Drug Administration to treat BPDCN. We report a case of an elderly patient with diagnosis of BPDCN who was treated initially with tagraxofusp followed by azacitidine and venetoclax combination on relapse.

Case Report: A 79 year old male presented with violaceous skin lesions. He had no other symptoms. Biopsy of these lesions was consistent with a diagnosis of BPDCN. Further testing showed no extracutaneous involvement. Tagraxofusp was started at full dose (12 mcg/kg). This dose was not tolerated well. Patient could only tolerate the lowest dose (5 mcg/kg). Toxicities included elevated liver function tests, hyperglycemia, capillary leak syndrome, and pancreatitis. Dose escalation on progression was not possible due to side effects. Treatment was switched to venetoclax and azacitidine. Combination treatment was tolerated very well and patient showed major cutaneous response after 5 cycles and continues to do well.

Discussion: Tagraxofusp is a novel therapy that needs more real-world experience. This case describes the clinical course of an elderly patient on tagraxofusp. We also review the literature of azacytidine/venetoclax combination as a potential yet tolerable treatment option for this rare disease entity. This is the fourth case in literature to be treated with this combination.