Application of blinatumomab, a bispecific anti-CD3/CD19 T-cell engager, in treating severe systemic sclerosis: A case study.

Systemic sclerosis, a severe inflammatory autoimmune disease, shares a common thread with cancer through the underlying mechanism of inflammation. This inflammatory milieu not only drives the immune dysregulation characteristic of autoimmune diseases but also plays a pivotal role in the pathogenesis of cancer. Among the cellular components involved, B cells have emerged as key players in hematologic tumor and autoimmune disease, contributing to immune dysregulation and persistent tissue fibrosis in systemic sclerosis, as well as tumor progression and immune evasion in cancer. Consequently, novel therapeutic strategies targeting B cells hold promise in both conditions. Recent exploration of CD19 CAR T cells in severe systemic sclerosis patients has shown great potential, but also introduced possible risks and drawbacks associated with viral vectors, prolonged CAR T cell persistence, lengthy production timelines, high costs, and the necessity of conditioning patients with organotoxic and fertility-damaging chemotherapy. Given these challenges, alternative CD19-depleting approaches are of high interest for managing severe systemic autoimmune diseases. Here, we present the pioneering use of blinatumomab, a bispecific anti-CD3/anti-CD19 T cell engager in a patient with progressive, severe systemic sclerosis, offering a promising alternative for such challenging cases.

Single agent subcutaneous blinatumomab for advanced acute lymphoblastic leukemia.

Blinatumomab is a BiTE® (bispecific T-cell engager) molecule that redirects CD3+ T-cells to engage and lyse CD19+ target cells. Here we demonstrate that subcutaneous (SC) blinatumomab can provide high efficacy and greater convenience of administration. In the expansion phase of a multi-institutional phase 1b trial (ClinicalTrials.gov, NCT04521231), heavily pretreated adults with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) received SC blinatumomab at two doses: (1) 250 µg once daily (QD) for week 1 and 500 µg three times weekly (TIW) thereafter (250 µg/500 µg) or (2) 500 µg QD for week 1 and 1000 µg TIW thereafter (500 µg/1000 µg). The primary endpoint was complete remission/complete remission with partial hematologic recovery (CR/CRh) within two cycles. At the data cutoff of September 15, 2023, 29 patients were treated: 14 at the 250 µg/500 µg dose and 13 at 500 µg/1000 µg dose. Data from two ineligible patients were excluded. At the end of two cycles, 12 of 14 patients (85.7%) from the 250 µg/500 µg dose achieved CR/CRh of which nine patients (75.0%) were negative for measurable residual disease (MRD; <10-4 leukemic blasts). At the 500 µg/1000 µg dose, 12 of 13 patients (92.3%) achieved CR/CRh; all 12 patients (100.0%) were MRD-negative. No treatment-related grade 4 cytokine release syndrome (CRS) or neurologic events (NEs) were reported. SC injections were well tolerated and all treatment-related grade 3 CRS and NEs responded to standard-of-care management, interruption, or discontinuation. Treatment with SC blinatumomab resulted in high efficacy, with high MRD-negativity rates and acceptable safety profile in heavily pretreated adults with R/R B-ALL.

Survival outcomes in patients with relapsed/refractory or MRD-positive B-cell acute lymphoblastic leukemia treated with blinatumomab.

Blinatumomab has demonstrated significant efficacy in adult and pediatric patients with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-cell ALL) and patients with measurable residual disease (MRD). This review aimed to compare median relapse-free survival (RFS) and median overall survival (OS) in adult and pediatric patients with R/R or MRD-positive B-cell ALL from pivotal studies [MT-103-211 and TOWER for adults with Philadelphia chromosome (Ph)-negative R/R B-cell ALL, ALCANTARA for adults with Ph-positive R/R B-cell ALL, MT-103-203 for adults with MRD-positive B-cell ALL, and MT-103-205 for pediatric patients with R/R B-cell ALL], with the median RFS and OS from retrospective analyses, country or ethnicity-specific studies, and studies based on real-world evidence (RWE) identified from a literature search. Adults with Ph-negative R/R B-cell ALL who received blinatumomab as first salvage demonstrated a numerically longer median OS compared with that in patients from pivotal studies (MT-103-211 and TOWER) without additional safety concerns. In pediatric patients with R/R B-cell ALL treated with blinatumomab, the median RFS and OS from retrospective analyses and country/ethnicity-specific studies were comparable with the median RFS and OS from the pivotal study MT-103-205. The median RFS and OS from RWE studies in adults with R/R B-cell ALL were numerically longer than the median RFS and OS from pivotal studies (MT-103-211, TOWER, and ALCANTARA); however, this trend was not observed in pediatric patients with R/R B-cell ALL. In conclusion, this analysis identified first salvage adults with Ph-negative R/R B-cell ALL as particularly well-suited for treatment with blinatumomab since survival outcomes from retrospective analyses reported in this patient subgroup were numerically better compared with those from pivotal studies without additional safety signals.

Transient and fully reversible changes in laboratory parameters and modifications of the cytokine profile during blinatumomab treatment in children with relapsed or refractory B-cell acute lymphoblastic leukemia.

We analyzed changes in laboratory parameters, including blood counts, liver enzymes, inflammation and coagulation markers, and cytokines, from 70 blinatumomab-treated pediatric patients (NCT01471782). Overall, trends were consistent in responders and nonresponders. Platelets and lymphocytes peaked on day (D) 10 in cycle 1 and returned to baseline on D42 and D29, respectively. Neutrophils peaked on D2 and returned to baseline on D42. Alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and bilirubin peaked on D17, reversing to baseline on D29; total protein levels were constant. These findings indicate that blinatumomab-induced changes in laboratory parameters were transient, reversible, and not requiring treatment interruptions in responders and nonresponders.

Children's Oncology Group AALL1331: Phase III Trial of Blinatumomab in Children, Adolescents, and Young Adults With Low-Risk B-Cell ALL in First Relapse.

PURPOSE: Blinatumomab, a bispecific T-cell engager immunotherapy, is efficacious in relapsed/refractory B-cell ALL (B-ALL) and has a favorable toxicity profile. One aim of the Children's Oncology Group AALL1331 study was to compare survival of patients with low-risk (LR) first relapse of B-ALL treated with chemotherapy alone or chemotherapy plus blinatumomab. PATIENTS AND METHODS: After block 1 reinduction, patients age 1-30 years with LR first relapse of B-ALL were randomly assigned to block 2/block 3/two continuation chemotherapy cycles/maintenance (arm C) or block 2/two cycles of continuation chemotherapy intercalated with three blinatumomab blocks/maintenance (arm D). Patients with CNS leukemia received 18 Gy cranial radiation during maintenance and intensified intrathecal chemotherapy. The primary and secondary end points were disease-free survival (DFS) and overall survival (OS). RESULTS: The 4-year DFS/OS for the 255 LR patients accrued between December 2014 and September 2019 were 61.2% ± 5.0%/90.4% ± 3.0% for blinatumomab versus 49.5% ± 5.2%/79.6% ± 4.3% for chemotherapy (P = .089/P = .11). For bone marrow (BM) ± extramedullary (EM) (BM ± EM; n = 174) relapses, 4-year DFS/OS were 72.7% ± 5.8%/97.1% ± 2.1% for blinatumomab versus 53.7% ± 6.7%/84.8% ± 4.8% for chemotherapy (P = .015/P = .020). For isolated EM (IEM; n = 81) relapses, 4-year DFS/OS were 36.6% ± 8.2%/76.5% ± 7.5% for blinatumomab versus 38.8% ± 8.0%/68.8% ± 8.6% for chemotherapy (P = .62/P = .53). Blinatumomab was well tolerated and patients had low adverse event rates. CONCLUSION: For children, adolescents, and young adults with B-ALL in LR first relapse, there was no statistically significant difference in DFS or OS between the blinatumomab and standard chemotherapy arms overall. However, blinatumomab significantly improved DFS and OS for the two thirds of patients with BM ± EM relapse, establishing a new standard of care for this population. By contrast, similar outcomes and poor DFS for both arms were observed in the one third of patients with IEM; new treatment approaches are needed for these patients (ClinicalTrials.gov identifier: NCT02101853).

Low leukemia burden improves blinatumomab efficacy in patients with relapsed/refractory B-cell acute lymphoblastic leukemia.

BACKGROUND: A lower baseline bone marrow blast percentage (bBMB%) is associated with better outcomes in patients with B-cell acute lymphoblastic leukemia (B-ALL) receiving blinatumomab. The objective of this analysis was to investigate the association between bBMB% and treatment outcomes in relapsed/refractory (R/R) B-ALL. METHODS: Data from five trials of blinatumomab for R/R B-ALL were pooled for analyses. Patients were placed in one of three groups: group 1, ≥50% bBMBs; group 2, ≥25% to <50% bBMBs; group 3, ≥5% to <25% bBMBs. Response and survival outcomes were compared between groups. RESULTS: Data from 683 patients (166 pediatric, 517 adult) were analyzed. Collectively, patients in groups 2 and 3 had significantly higher odds of achieving a complete remission (CR) (odds ratio [OR], 3.50 [95% confidence interval (CI), 2.23-5.48] and 3.93 [95% CI, 2.50-6.18], respectively; p < .001) and minimal/measurable residual disease response (OR, 2.61 and 3.37, respectively; p < .001) when compared with group 1 (reference). Groups 2 and 3 had a 37% and 46% reduction in the risk of death (hazard ratio [HR], 0.63 and 0.54, respectively; p < .001) and a 41% and 43% reduction in the risk of an event (relapse or death) (HR, 0.59 and 0.57, respectively; p < .001) compared with group 1. No significant differences in response or survival outcomes were observed between groups 2 and 3. Seven of nine patients whose bBMB% was lowered to <50% with dexamethasone achieved CR with blinatumomab. CONCLUSION: Any bBMB% <50% was associated with improved efficacy following blinatumomab treatment for R/R B-ALL.

Real-world use of blinatumomab in adult patients with B-cell acute lymphoblastic leukemia in clinical practice: results from the NEUF study.

This retrospective observational study (NEUF) included adult patients with B-cell acute lymphoblastic leukemia (B-cell ALL) who had received blinatumomab for the treatment of minimal residual disease-positive (MRD+) or relapsed/refractory (R/R) B-cell ALL via an expanded access program (EAP). Patients were eligible if blinatumomab was initiated via the EAP between January 2014 and June 2017. Patients were followed from blinatumomab initiation until death, entry into a clinical trial, the end of follow-up, or the end of the study period (December 31, 2017), whichever occurred first. Of the 249 adult patients included, 109 were MRD+ (83 Philadelphia chromosome-negative [Ph-] and 26 Philadelphia chromosome-positive [Ph+]) and 140 had a diagnosis of R/R B-cell ALL (106 Ph- and 34 Ph+). In the MRD+ group, within the first cycle of blinatumomab treatment, 93% (n = 49/53) of Ph- and 64% (n = 7/11) of Ph+ patients with evaluable MRD achieved an MRD response (MRD <0.01%). Median overall survival (OS) was not reached over a median follow-up time of 18.5 months (Ph-, 18.8 [range: 5.1-34.8] months; Ph+, 16.5 [range: 1.8-31.6] months). In the R/R group, within two cycles of blinatumomab, 51% of Ph- and 41% of Ph+ patients achieved complete hematologic remission (CR/CRh/CRi), and 83% of Ph- and 67% of Ph+ MRD-evaluable patients in CR/CRh/CRi achieved an MRD response. Median (95% confidence interval) OS was 12.2 (7.3-24.2) months in the R/R Ph- subgroup and 16.3 (5.3-not estimated) months in the R/R Ph+ subgroup. This large, real-world data set of adults with B-cell ALL treated with blinatumomab confirms efficacy outcomes from published studies.

Efficacy and safety of blinatumomab in Chinese adults with Ph-negative relapsed/refractory B-cell precursor acute lymphoblastic leukemia: A multicenter open-label single-arm China registrational study.

OBJECTIVES: The prognosis for adults with relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is poor. Blinatumomab is a CD3/CD19-directed BiTE® (bispecific T-cell engager) molecule approved globally for the treatment of BCP-ALL in adults and children. This multicenter open-label single-arm China registrational study evaluated the safety, efficacy, and pharmacokinetics of blinatumomab in Chinese adults with Philadelphia chromosome-negative (Ph-) R/R BCP-ALL (NCT03476239). METHODS: Patients aged ≥ 18 years were treated with up to 5 cycles of blinatumomab. The primary objective was to evaluate the hematological response rate (complete remission/complete remission with partial hematological recovery [CR/CRh]) within 2 cycles of blinatumomab. RESULTS: At the interim analysis (April 12, 2019), 90 patients (median age 31.5 years [range: 18-74]; 53.3% female; 77.8% with bone marrow blasts ≥ 50% at study entry) were enrolled at 23 study centers in China and had received blinatumomab. As of data cutoff, 43 patients (47.8%) continued the study. The CR/CRh rate within 2 cycles of blinatumomab was 45.6% (41/90 [CR, 37; CRh, 4]; 95% CI: 35.0-56.4). Median overall survival was 9.2 months (95% CI: 6.5-11.7); median relapse-free survival was 4.3 months (95% CI: 3.2-9.4). Mean serum concentration at steady-state and systemic clearance of blinatumomab in Chinese patients were within the range reported in adults from global clinical trials. No new safety risks were identified in Chinese patients. CONCLUSIONS: The efficacy and safety of blinatumomab in these heavily pre-treated Chinese patients with Ph- R/R BCP-ALL is comparable to that for patients within global clinical trials.

Blinatumomab overcomes poor prognostic impact of measurable residual disease in pediatric high-risk first relapse B-cell precursor acute lymphoblastic leukemia.

BACKGROUND: Blinatumomab, a CD3/CD19 BiTE® (bispecific T cell engager) molecule, was superior to high-risk third course consolidation chemotherapy (HC3) in prolonging event-free survival (EFS) in children with high-risk first relapse B-cell precursor acute lymphoblastic leukemia (B-ALL). Here, we report results from a post hoc measurable residual disease (MRD) analysis of this phase 3 study (NCT02393859). PROCEDURE: Children >28 days and <18 years with high-risk first-relapse B-ALL in cytomorphological complete remission (M1 marrow, <5% blasts) or with M2 marrow (≥5% and <25% blasts) after induction and two cycles of high-risk consolidation chemotherapy (baseline) were enrolled in this trial. Patients received one cycle of blinatumomab (15 µg/m2 /day, 4 weeks, continuous intravenous infusion) or HC3. The primary endpoint was EFS. In this post hoc analysis, patients with MRD <10-4 by PCR were grouped as having positive but not quantifiable (pbnq) or undetectable disease. RESULTS: A higher proportion of patients with MRD <10-4 had undetectable versus pbnq disease after blinatumomab (day 29) than after HC3 (p = 0.0367). Of the 22 patients with MRD ≥10-4 at baseline who achieved MRD remission after blinatumomab, 20 (91%) achieved MRD <10-4 remission by day 15. Patients treated with blinatumomab had improved EFS and overall survival compared with those treated with HC3 independent of end-of-induction or baseline (end-of-second consolidation) MRD levels. CONCLUSIONS: Blinatumomab was more efficacious than HC3 regardless of MRD status before treatment. These data support the role of blinatumomab in inducing deep MRD remission, negating the poor prognostic value of MRD.

Blinatumomab in pediatric relapsed/refractory B-cell acute lymphoblastic leukemia: RIALTO expanded access study final analysis.

The safety and efficacy of blinatumomab, a CD3/CD19-directed bispecific molecule, were examined in an open-label, single-arm, expanded access study (RIALTO). Children (>28 days and <18 years) with CD19+ relapsed/refractory B-cell precursor acute lymphoblastic leukemia (R/R B-ALL) received up to 5 cycles of blinatumomab by continuous infusion (cycle: 4 weeks on/2 weeks off). The primary end point was incidence of adverse events. Secondary end points included complete response (CR) and measurable residual disease (MRD) response within the first 2 cycles and relapse-free survival (RFS), overall survival (OS), and allogeneic hematopoietic stem cell transplant (alloHSCT) after treatment. At final data cutoff (10 January 2020), 110 patients were enrolled (median age, 8.5 years; 88% had ≥5% baseline blasts). A low incidence of grade 3 or 4 cytokine release syndrome (n = 2; 1.8%) and neurologic events (n = 4; 3.6%) was reported; no blinatumomab-related fatal adverse events were recorded. The probability of response was not affected by the presence of cytogenetic/molecular abnormalities. Median OS was 14.6 months (95% confidence interval [CI]: 11.0-not estimable) and was significantly better for MRD responders vs MRD nonresponders (not estimable vs 9.3; hazard ratio, 0.18; 95% CI: 0.08-0.39). Of patients achieving CR after 2 cycles, 73.5% (95% CI: 61.4%-83.5%) proceeded to alloHSCT. One-year OS probability was higher for patients who received alloHSCT vs without alloHSCT after blinatumomab (87% vs 29%). These findings support the use of blinatumomab as a safe and efficacious treatment of pediatric R/R B-ALL. This trial was registered at www.clinicaltrials.gov as #NCT02187354.

Impact of Blinatumomab Treatment on Bone Marrow Function in Patients with Relapsed/Refractory B-Cell Precursor Acute Lymphoblastic Leukemia.

Association of blinatumomab treatment with myelosuppression was examined in this study. Peripheral blood counts were assessed prior to, during, and after blinatumomab treatment in patients with relapsed/refractory Philadelphia chromosome-negative (Ph-) B-cell precursor (BCP) acute lymphoblastic leukemia (ALL; n = 267) and Ph+ BCP-ALL (n = 45) from the TOWER and ALCANTARA studies, respectively, or chemotherapy in patients with Ph- BCP-ALL (n = 109) from the TOWER study; all the patients with relapsed/refractory BCP-ALL and responders achieving complete remission (CR) or CR with partial/incomplete hematological recovery (CRh/CRi) were evaluated. Event-free survival (EFS) and overall survival (OS) were assessed in patients achieving CR and CRh/CRi. Median leukocyte, neutrophil, and platelet counts increased during two blinatumomab cycles but remained low longer after chemotherapy. Among the responders, there was a trend that a greater proportion of patients achieved CR with blinatumomab (Ph-, 76.5%; Ph+, 77.8%) versus with chemotherapy (Ph-, 63.6%). In the TOWER study, the survival prognosis for patients achieving CRh/CRi versus CR with blinatumomab was more similar (median OS, 11.9 (95% CI, 3.9-not estimable (NE)) vs. 15.0 (95% CI, 10.4-NE) months, p = 0.062) than with chemotherapy (5.2 (95% CI, 1.6-NE) vs. 18.9 (95% CI, 9.3-NE) months, p = 0.013). Blinatumomab treatment, with only temporary and transient myelosuppression, resulted in a greater survival benefit than chemotherapy.

CD19 expression in pediatric patients with relapsed/refractory B-cell precursor acute lymphoblastic leukemia pre- and post-treatment with blinatumomab.

Blinatumomab is a BiTE® (bispecific T-cell engager) immuno-oncology therapy, which has demonstrated significant activity in patients with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (R/R B-ALL); however, a subset of patients relapse. Monitoring expression of cluster of differentiation (CD)19 in relapsed patients is critical to inform sequencing of subsequent therapies. The expression of CD19 in 59 pediatric patients with R/R B-ALL was analyzed on the day of diagnosis of R/R B-ALL and on days 15 and 29 of cycle 1 of blinatumomab. Most patients treated with one cycle of blinatumomab retained expression of CD19, and would therefore be eligible for subsequent anti-CD19 CAR T-cell therapy.

Relationship of T- and B-cell kinetics to clinical response in patients with relapsed/refractory non-Hodgkin lymphoma treated with blinatumomab.

Blinatumomab is a first-in-class immunotherapy based on the bispecific T-cell engager (BiTE®) immune-oncology platform, which redirects CD3+ T cells to kill CD19+ target cells. The objective of this analysis was to describe the correlation between B- and T-cell kinetics and response to blinatumomab in patients with relapsed or refractory (r/r) non-Hodgkin lymphoma (NHL). The clinical efficacy of treatment with blinatumomab in patients with r/r NHL was recently investigated in a phase 1 dose-escalation and expansion trial (NCT00274742) wherein 76 patients received blinatumomab by continuous intravenous infusion at various doses (0.5-90 µg/m2/day). B-Cell depletion and expansion of CD3+, CD4+, and CD8+ T cells was analyzed in patients stratified per clinical response (complete response [CR], n = 16; partial response [PR], stable disease [SD], or progressive disease [PD], n = 54) for at least 4 weeks (additional 4 weeks after clinical benefit) from the date of administration of blinatumomab until dose-limiting toxicity or PD. B-cell depletion kinetics were faster in patients who had a CR than in patients who did not have a complete response (PR, SD, or PD). T-cell expansion (T-cell counts exceeding the baseline level on day 22) was more pronounced in patients with CR than in patients without CR. T-cell expansion in patients with CR correlated with increased T-cell counts of both CD4+ and CD8+ T cells compared with patients without CR. Patients with r/r NHL who achieved a CR had faster B-cell depletion and increased expansion of CD3+, CD4+, and CD8+ T cells than patients who did not achieve a CR.

Blinatumomab as first salvage versus second or later salvage in adults with relapsed/refractory B-cell precursor acute lymphoblastic leukemia: Results of a pooled analysis.

BACKGROUND: Blinatumomab is a BiTE® immuno-oncology therapy indicated for the treatment of patients with relapsed or refractory (r/r) B-cell precursor (BCP) acute lymphoblastic leukemia (ALL). Aims To assess the efficacy and safety of blinatumomab as first salvage versus second or later salvage in patients with r/r BCP ALL. Materials & Methods Patient-level pooled data were used for this analysis. In total, 532 adults with r/r BCP ALL treated with blinatumomab were included (first salvage, n = 165; second or later salvage, n = 367). Results Compared with patients who received blinatumomab as second or later salvage, those who received blinatumomab as first salvage had a longer median overall survival (OS; 10.4 vs. 5.7 months; HR, 1.58; 95% CI, 1.26-1.97; P < .001) and relapse-free survival (10.1 vs. 7.3 months; HR, 1.38; 95% CI, 0.98-1.93; P = .061), and higher rates of remission (n = 89 [54%] vs. n = 150 [41%]; odds ratio, 0.59; 95% CI, 0.41-0.85; P = .005), minimal residual disease response (n = 68 [41%] vs. n = 118 [32%]), and allogeneic hematopoietic stem cell transplant (alloHSCT) realization (n = 60 [36%] vs. n = 88 [24%]), and alloHSCT in continuous remission (n = 33 [20%] vs. n = 52 (14%]). In a subgroup analysis, there was no apparent effect of prior alloHSCT on median OS in either salvage group. The safety profile of blinatumomab was generally similar between the groups; however, cytokine release syndrome, febrile neutropenia, and infection were more frequent with second or later salvage than with first salvage. Discussion In this pooled analysis, the logistic regression analyses indicated greater benefit with blinatumomab as first salvage than as second or later salvage, as evident by the longer median OS, longer median RFS, and higher rates of remission. Conclusion Overall, blinatumomab was beneficial as first salvage and as second or later salvage, but the effects were favorable as first salvage.

Effect of Postreinduction Therapy Consolidation With Blinatumomab vs Chemotherapy on Disease-Free Survival in Children, Adolescents, and Young Adults With First Relapse of B-Cell Acute Lymphoblastic Leukemia: A Randomized Clinical Trial.

Importance: Standard chemotherapy for first relapse of B-cell acute lymphoblastic leukemia (B-ALL) in children, adolescents, and young adults is associated with high rates of severe toxicities, subsequent relapse, and death, especially for patients with early relapse (high risk) or late relapse with residual disease after reinduction chemotherapy (intermediate risk). Blinatumomab, a bispecific CD3 to CD19 T cell-engaging antibody construct, is efficacious in relapsed/refractory B-ALL and has a favorable toxicity profile. Objective: To determine whether substituting blinatumomab for intensive chemotherapy in consolidation therapy would improve survival in children, adolescents, and young adults with high- and intermediate-risk first relapse of B-ALL. Design, Setting, and Participants: This trial was a randomized phase 3 clinical trial conducted by the Children's Oncology Group at 155 hospitals in the US, Canada, Australia, and New Zealand with enrollment from December 2014 to September 2019 and follow-up until September 30, 2020. Eligible patients included those aged 1 to 30 years with B-ALL first relapse, excluding those with Down syndrome, Philadelphia chromosome-positive ALL, prior hematopoietic stem cell transplant, or prior blinatumomab treatment (n = 669). Interventions: All patients received a 4-week reinduction chemotherapy course, followed by randomized assignment to receive 2 cycles of blinatumomab (n = 105) or 2 cycles of multiagent chemotherapy (n = 103), each followed by transplant. Main Outcome and Measures: The primary end point was disease-free survival and the secondary end point was overall survival, both from the time of randomization. The threshold for statistical significance was set at a 1-sided P <.025. Results: Among 208 randomized patients (median age, 9 years; 97 [47%] females), 118 (57%) completed the randomized therapy. Randomization was terminated at the recommendation of the data and safety monitoring committee without meeting stopping rules for efficacy or futility; at that point, 80 of 131 planned events occurred. With 2.9 years of median follow-up, 2-year disease-free survival was 54.4% for the blinatumomab group vs 39.0% for the chemotherapy group (hazard ratio for disease progression or mortality, 0.70 [95% CI, 0.47-1.03]); 1-sided P = .03). Two-year overall survival was 71.3% for the blinatumomab group vs 58.4% for the chemotherapy group (hazard ratio for mortality, 0.62 [95% CI, 0.39-0.98]; 1-sided P = .02). Rates of notable serious adverse events included infection (15%), febrile neutropenia (5%), sepsis (2%), and mucositis (1%) for the blinatumomab group and infection (65%), febrile neutropenia (58%), sepsis (27%), and mucositis (28%) for the chemotherapy group. Conclusions and Relevance: Among children, adolescents, and young adults with high- and intermediate-risk first relapse of B-ALL, postreinduction treatment with blinatumomab compared with chemotherapy, followed by transplant, did not result in a statistically significant difference in disease-free survival. However, study interpretation is limited by early termination with possible underpowering for the primary end point. Trial Registration: ClinicalTrials.gov Identifier: NCT02101853.