FDA Approves First Drug to Treat Blastic Plasmacytoid Dendritic Cell Neoplasm

The FDA has approved Stemline Therapeutics’ tagraxofusp-erzs (Elzonris), the first drug approved to treat blastic plasmacytoid dendritic cell neoplasm (BPDCN) in adults and in pediatric patients aged 2 years or older.

BPDCN is a rare, aggressive disease of the bone marrow and blood that can affect multiple organs, including the lymph nodes and skin, and often presents or evolves into acute leukemia.

In a statement announcing the approval, Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, explained that “Prior to today’s approval, there had been no FDA-approved therapies for BPDCN. The standard of care has been intensive chemotherapy followed by bone marrow transplantation. Many patients with BPDCN are unable to tolerate this intensive therapy, so there is an urgent need for alternative treatment options.”

The efficacy of the drug was evaluated in the largest multicenter prospective study ever conducted in patients with BPDCN, results of which were announced at the 2017 American Society of Hematology Annual Meeting and Exposition. In the trial, 13 patients with BPDCN received Elzonris as first-line treatment. In total, 7 patients (54%) achieved a complete response (95% CI, 25.1%-80.8%). The overall response rate was 77%, and 46% of patients were bridged to stem cell transplantation following remission. At 5 to 8 months, 86% of complete responders were relapse-free.

The most common treatment-emergent adverse events were hypoalbuminemia (47%), aspartate aminotransferase increase (46%), alanine aminotransferase increase (45%), nausea (28%), and thrombocytopenia (28%). Capillary leak syndrome, which led to death in 3 patients, occurred in 19% of patients.

“[Elzonris] has demonstrated efficacy with meaningful clinical benefit in BPDCN while maintaining a manageable safety profile, particularly notable in this predominantly older population, representing a major advance in the management of BPDCN,” said Andrew A. Lane, MD, PhD, director of the BPDCN center at the Dana-Farber Cancer Institute and assistant professor of medicine at Harvard Medical School, a coinvestigator on the study. He added that the drug will also be investigated in combination with other agents in clinical trials of other aggressive hematological cancers.

The drug was granted a Breakthrough Therapy Designation and an Orphan Drug Designation by the FDA.