Rare Disease Report

FDA Approves Pair of Therapies for Rare Blood Diseases

DECEMBER 21, 2018
Kevin Kunzmann
The US Food and Drug Administration (FDA) approved a pair of therapies indicated for rare blood diseases on Friday.


Tagraxofusp-erzs for Blastic Plasmocytoid Dendritic Cell Neoplasm

First, they approved tagraxofusp-erzs infusion (Elzonris) for the treatment of blastic plasmacytoid dendritic cell neoplasm (BPDCN) in adult and pediatric patients aged 2 years or older.

With the approval, the infusion therapy from Stemline Therapeutics becomes the first drug approved for the rare bone marrow and blood disease that commonly presents as leukemia or evolves into active leukemia.

BPDCN, which is primarily treated with intensive chemotherapy and bone marrow transplantation, has lacked options for patients potentially unable to withstand such therapies. In a statement accompanying the announced approval, Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products, called Elzonris’ approval an answer to an “urgent need for alternative treatment options.”

The therapy’s efficacy was assessed in a pair of cohort, single-arm clinical trials. In the first, 7 of 13 (54%) patients with untreated BPDCN achieved complete remission (CR), or CR with a skin abnormality not indicative of active disease (CRc). In the second, 2 of 15 patients with relapsed or refractory BPDCN achieved either CR or CRc.

Patients reported common side effects of capillary leak syndrome, nausea, fatigue, peripheral edema, fever, chills, and weight increase.

The FDA advises that providers monitor liver enzyme levels and for signs of intolerance to the infusion.


Ravulizumab for Paroxysmal Nocturnal Hemoglobinuria

The FDA also approved ravulizumab (Ultomiris) for the treatment of life-threatening blood disease paroxysmal nocturnal hemoglobinuria (PNH) in adult patients.

The approved novel therapy improves on the current market’s standard treatment, administered once every 2 weeks, with an injection treatment administered once every 8 weeks. Ravulizumab, Pazdur noted, will “change the way that patients with PNH are treated.”

The rare acquired disorder PNH is characterized by red blood cell rupture or destruction due to a missing protein intended for protecting patients’ immune systems. The condition is often noted in sudden, episodic instances of premature red blood cell destruction, triggered by infections or physical exertion.

Patients with PNH are susceptible to symptoms of severe anemia, profound fatigue, kidney disease, and more. They are most commonly diagnosed in young adulthood.

As a long-acting complement inhibitor that prevents hemolysis, ravulizumab was proven efficacious in a clinical trial involving 246 treatment-naïve patients with PNH. Patients were randomized to receive either ravulizumab or standard-of-care eculizumab.

Patients treated with the investigative therapy reported non-inferiority to those treated with eculizumab. They did not receive transfusions, and reported similar incidence of hemolysis.

A second trial involving 195 patients with PNH—who had been treated with eculizumab for the past 6 months—additionally found that those then treated with ravulizumab reported non-inferiority to eculizumab, based on clinical metrics including hemolysis and transfusion avoidance.

Common side effects for patients included headache and upper respiratory infection. The FDA advises that providers use caution when administering therapy to patients with other systemic infections.

Ravulizumab’s prescribing information includes a Boxed Warning advising providers and patients on the risk of life-threatening meningococcal infections and sepsis.

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