Ninety percent of patients with previously untreated blastic plasmacytoid dendritic cell neoplasm (BPDCN) responded to treatment with tagraxofusp, a CD123-targeted agent previously known as SL-401, according to results published in the New England Journal of Medicine. Response rates also were high in patients with relapsed disease, at 67%.
Based in part on these findings, the U.S. Food and Drug Administration approved tagraxofusp for the treatment of adults and children (≥2 years of age) with BPDCN, marking the first approval for this rare disease.
“This agent is now the only targeted agent approved in BPDCN, and it is the first-ever CD123-directed therapy approved,†lead study author Naveen Pemmaraju, MD, of the MD Anderson Cancer Center, told ASH Clinical News.
This nonrandomized, multistage, open-label, multicenter trial evaluated single-agent tagraxofusp in 47 patients (median age = 70 years; range = 22-84 years): 32 had treatment-naïve disease and 15 had previously treated BPDCN.
The study was conducted in four stages:
- stage 1: dose-escalation phase (n=9)
- stage 2: expansion phase (n=23)
- stage 3: pivotal phase, including a cohort of 13 patients with treatment-naïve BPDCN
- stage 4: continued-access phase, including 2 patients with previously treated BPDCN
Tagraxofusp was administered on days 1 through 5 of each 21-day cycle, at either 7 μg/kg or 12 μg/kg. Patients continued treatment with tagraxofusp until disease progression or unacceptable toxicity.
The study’s primary endpoint was the combined rate of complete response (CR) and clinical CR in patients who received tagraxofusp as frontline treatment. Response duration served as a secondary endpoint.
After a median follow-up of 19 months (range = 1-42 months), 29 previously untreated patients received tagraxofusp at a dose of 12 μg/kg. Twenty-one patients (72%) experienced a CR, and the overall response rate was 90%. Notably, 13 patients (45%) in this group were subsequently bridged to hematopoietic cell transplantation.