Short-course blinatumomab (CD19×CD3 BiTE) clears MRD in B-ALL and gets 90% to transplant in a resource-limited program

Blinatumomab is a CD19×CD3 bispecific T-cell engager (BiTE) given here as a deliberately shortened “MRD-eradication” bridge to allogeneic HCT in CD19+ B-ALL patients in CR with detectable MRD and ≤5% blasts (n=20; median age 10 years, 0.8–59; 8 adults; 19/20 Ph-negative; heavily pretreated with mean 3 prior lines; 35% primary refractory; 65% relapsed). After a single reduced course (adults: fixed-dose 175µg over 7 inpatient days; pediatrics: 5µg/m²/day for 4–7 days with ramp-up to 15µg/m²/day up to 21 days outpatient), 90% (18/20) achieved undetectable MRD by next-generation flow (≤0.001%; reported as MRDx10^-5) and proceeded to HCT; 2/20 did not clear MRD and did not transplant—broadly consistent with “full-course” blinatumomab in MRD+ CR where ~85% convert after 1 cycle in the registrational dataset. Toxicity pre-HCT was mostly low-grade (CRS 35%, all grade 1; ICANS 15% with one grade 3; no pre-HCT deaths and no other grade ≥3 AEs reported). Post-HCT, acute GVHD occurred in 50% (1 grade 3; remainder grade 1–2); with 33 months median follow-up, there were 2 relapses after HCT (one isolated iris→skin in an adult at 10 months; one marrow relapse in a child at 4 months) and 2 non-relapse deaths in remission (pneumonia, thromboembolism); 24-month OS was 63% and EFS 55%—directionally in the range expected for high-risk R/R patients bridged to allo-HCT, but hard to benchmark cleanly given mixed age groups, donor types (mostly haploidentical), and conditioning.