Single-agent blinatumomab demonstrated antileukemia activity in pediatric patients with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL), according to a study published in the Journal of Clinical Oncology.
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ALL is the most common malignant disease in children. Those with second or greater relapse or refractory disease have a poor prognosis, even after being treated with combination chemotherapy and allogeneic hematopoietic stem-cell transplantation.
The study, led by Arend von Stackelberg, MD, Charité Campus Virchow-Klinikum (Berlin, Germany), sampled patients 18-years or younger with relapsed or refractory BCP-ALL in a phase I dosage-escalation trial and a phase II trial, using 6-week treatment cycles of blinatumomab, a bispecific T-cell engager antibody construct targeting CD19 on B-cell lymphoblasts. On the basis of this study, blinatumomab was granted accelerated approval by the FDA for pediatric patients with Philadelphia chromosome-negative relapsed or refractory BCP-ALL.
The study treated 49 patients in phase I and 44 patients in phase II. Primary endpoints were maximum-tolerated dosage for phase I and complete remission rate within the first two cycles for phase II. In phase I, four patients had dose limiting toxicities in cycle 1. Three patients experienced grade-4 cytokine-release syndrome. One patient experienced fatal respiratory failure. Researchers determined the maximum-tolerated dose of blinatumomab was 15 mcg/m2 per day.
In phase II, patients were given 5 mcg/m2 per day for the first week and a dose of 15 mcg/m2 every day afterwards. Among the 70 total patients who received the recommended dose, 39% had complete remission within the first two cycles, and 52% had complete minimal residual disease response (MRD).
“Blinatumomab showed antileukemic activity across all age groups, including patients < 2 years old and those with unfavorable cytogenetics,” the researchers wrote.
The results of this study indicate that blinatumomab may represent an important new treatment option for pediatric BCP-ALL.
“This study supports further evaluation of blinatumomab in children with BCP-ALL, including those with first-relapse or newly diagnosed disease at high risk of treatment failure because of significant MRD burden or unfavorable cytogenetics,” the researchers concluded.
