FDA approves first treatment for BPDCN


Photo by Daniel Sone

Pharmacist holding drug vial

The U.S. Food and Drug Administration (FDA) has approved tagraxofusp-erzs (Elzonris) to treat patients age 2 and older who have blastic plasmacytoid dendritic cell neoplasm (BPDCN).

Tagraxofusp-erzs (formerly SL-401) is a CD123-directed cytotoxin that is the first FDA-approved treatment for BPDCN.

Tagraxofusp-erzs will be commercially available in early 2019, according to Stemline Therapeutics, makers of the drug.

The prescribing information for tagraxofusp-erzs contains a boxed warning noting that the drug is associated with an increased risk of capillary leak syndrome (CLS), which may be life-threatening or fatal.

The FDA previously granted tagraxofusp-erzs breakthrough therapy and orphan drug designations and assessed the drug under priority review.

The FDA’s approval of tagraxofusp-erzs was based on a phase 1 trial (STML-401-0114; NCT02113982).

The trial enrolled 47 patients with BPDCN, including 32 who were treatment-naïve and 15 who were previously treated.

Patients received tagraxofusp-erzs intravenously on days 1-5 of a 21-day cycle for multiple consecutive cycles. The trial had a dose-escalation stage (stage 1), an expansion stage (stage 2), a confirmatory stage (stage 3), and a stage that enabled uninterrupted access to tagraxofusp-erzs (stage 4).

In the confirmatory stage, 13 patients with treatment-naïve BPDCN received tagraxofusp-erzs at the recommended dose and schedule—12 mcg/kg daily for 5 days of a 21-day cycle.

Efficacy was based on the rate of complete response (CR) or clinical complete response (CRc). CRc was defined as CR with residual skin abnormality not indicative of active disease.

The CR/CRc rate was 53.8% (7/13), and the median duration of CR/CRc was not reached (range, 3.9 to 12.2 months).

The safety of tagraxofusp-erzs was assessed in 94 adults with treatment-naïve or previously treated myeloid malignancies, including 58 patients with BPDCN, who were treated at the recommended dose and schedule.

There were two fatal adverse events—both CLS. Eleven percent of patients discontinued treatment with tagraxofusp-erzs due to an adverse event. The most common of these were hepatic toxicities and CLS.

The most common adverse events overall were CLS (55%), nausea (49%), fatigue (45%), peripheral edema (43%), pyrexia (43%), and weight increase (31%).

The most common laboratory abnormalities were decreases in albumin (77%), platelets (67%), hemoglobin (60%), calcium (57%), and sodium (50%), as well as increases in glucose (87%), alanine aminotransferase (82%), and aspartate aminotransferase (79%).

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