Blinatumomab use in pediatric patients (pts) with relapsed/refractory B-precursor acute lymphoblastic leukemia (r/r ALL) from an open-label, multicenter, expanded access study.

Abstract

10530 Background:Blinatumomab (blin), a bispecific T-cell engaging antibody construct, has shown antileukemia activity and tolerability in pts with r/r ALL. We further evaluated safety and efficacy of blin in the first 40 pediatric pts with r/r ALL enrolled in an expanded access study (NCT02187354). Methods: Eligible pts (28 d to < 18 yrs) had ≥ 5% blasts and r/r ALL (refractory, ≥ 2 relapses or relapse after transplant [HCT]). Blin was dosed by continuous infusion (4 wks on/2 wks off) for up to 5 cycles (≥ 5 to < 25% blasts: 15 µg/m2/d; ≥ 25% blasts: 5 µg/m2/d on d1−7 in cycle 1, then 15 µg/m2/d). The primary endpoint was incidence of treatment-emergent (TE) and treatment-related (TR) adverse events (AEs); key efficacy endpoints were complete response (CR) and minimal residual disease (MRD, by PCR or flow cytometry) in the first 2 cycles, relapse-free survival, overall survival and HCT rate. Results: Of the first40 treated pts (median age, 9 [range, 1−17] yrs), 24 (60%) had ≥ 2 relapses, 20 (50%) relapsed after HCT and 5 (13%) were primary refractory; 18 (45%) had ≥ 50% blasts and 21 (53%) had prior HCT. Safety and key efficacy outcomes are shown in the table, including 63% CR in the first 2 cycles. There were 8 relapses and 20 deaths after treatment. Regardless of causality, the most frequent TEAEs were pyrexia (78%), cytokine release syndrome (CRS; 23%) vomiting (23%) and anemia (20%); all 9 CRS events were grade (gr) 1 or 2 and 1 tumor lysis syndrome was gr 3. 10 (25%) pts interrupted treatment and 2 (5%) discontinued due to TRAEs; 13 (33%) pts had gr ≥ 3 TRAEs, including 2 of 3 neurologic events (depressed level of consciousness and headache; both gr 3); 2 fatal AEs were considered unrelated to blin. Conclusions:Here single-agent blin showed antileukemia activity in pediatric pts with high-risk r/r ALL including t(17;19) and AEs consistent with those previously reported for r/r ALL. Clinical trial information: NCT02187354. [Table: see text]