Posttransplant maintenance with blinatumomab for children, adolescents, and young adults with relapsed and refractory B-cell acute lymphoblastic leukemia - results of phase I in SCT-ALL-BLIN21

Sep 29, 2026

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Posttransplant maintenance using blinatumomab was evaluated in CAYA with CD19-positive relapsed or refractory B-cell acute lymphoblastic leukemia after allogeneic hematopoietic cell transplantation beyond first complete remission. A multi-center phase I-II SCT-ALL-BLIN21 trial enrolled nine patients for phase I; six completed planned therapy. Grade 4 adverse events were hematologic, mainly lymphocytopenia and neutropenia. Discontinuation occurred with increased transaminase, grade 3 acute GVHD, and grade 4 neutropenia, supporting acceptable phase I safety and progression to phase II efficacy assessment.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages6

Reading Time15 min

AccessFree to download

Posttransplant maintenance trial overview

Rationale and study objective

Trial design and phase I participants

Safety outcomes and treatment discontinuation

Ethics approval, registration, and eligibility

Treatment schedule and dosing approach

LETTER TO THE EDITOR Posttransplant maintenance with blinatumomab forchildren, adolescents, and young adults with relapsed and refractory B-cell acute lymphoblastic leukemia: results of phase I in SCT-ALL-BLIN21 Relapsed and refractory B-cell acute lymphoblastic leukemia (R/R-B-ALL) is a significant risk factor for relapse following allogeneic hematopoietic cell transplantation (allo-HCT) in children, adolescents, and young adults (CAYA) . Posttransplant blinatumomab may improve the graft-versus-leukemic effect for CD19-positive minimum residual disease. We conducted a multi-center, uncontrolled, phase I-II trial (SCT-ALL-BLIN21) to evaluate the safety and efficacy of posttransplant maintenance therapy with blinatumomab (2 courses of 4 weeks each) in CAYA with CD19-positive R/RB-ALL who underwent allo-HCT beyond the first complete remission (CR) . Phase I involved nine patients (median age, 10 years; range, 4-20), six (67%) of whom completed the planned treatment. All grade 4 adverse events (AE) were hematological toxicities, primarily lymphocytopenia and neutropenia. Increased transaminase (grade 3, N=1), acute graft-versus-host disease (GVHD; grade 3, N=1), and neutropenia (grade 4, N=1) caused treatment discontinuation. The observed safety profile of phase I was acceptable, enabling the study to proceed to phase II, where the efficacy of blinatumomab will be evaluated. Despite a long-term survival rate of 80-90% for B-ALL in CAYA,1,2 the R/R-B-ALL relapse rate remains high after allo-HCT and is associated with poor patient outcomes.3-5 Developing new strategies is crucial to reduce the posttransplant relapse rate and improve patient prognosis, such as by posttransplant maintenance therapy. CD19 is a surface antigen expressed on most B-ALL with limited expression in normal tissues and is an ideal target for immunotherapy. Blinatumomab exhibits its antileukemic effect by mediating the engagement of CD3-positive T cells with CD19-positive cells.6 Posttransplant blinatumomab administration potentially improves the antileukemic effect of donor-derived CD3-positive T cells on residual CD19-positive leukemia cells, causing lower relapse and improved survival rates. However, concerns remain regarding its potential AE, including the development or exacerbation of GVHD, cytopenia, and cytokine release syndrome (CRS) .7-10 Gaballa et al. conducted a prospective, single-center study and revealed the safety and efficacy of blinatumomab in adult patients with B-ALL at a high risk of relapse 11 Our multi-center, uncontrolled, phase I-II trial (SCT-ALL-BLIN21), sponsored by the Japanese Childhood Cancer Group, aimed to evaluate the safety and efficacy of posttransplant maintenance therapy with blinatumomab (2 courses of 4 weeks each) in CAYA with CD19-positive R/R-B-ALL who underwent allo-HCT beyond first CR. This report presents the results of the phase I trial, focusing on blinatumomab safety evaluation. The National Hospital Organization Review Board for Clinical Trials (Nagoya, Japan) approved this study protocol (receipt number, C2021-004), which was previously published as a protocol paper 12 This study adhered to the Declaration of Helsinki and the Clinical Trial Act, and was registered at the Japan Registry of Clinical Trials (jRCTs041210154; [https://](https://)[ ](https://)[jrct.niph.go.jp/en-latest-detail/jRCTs041210154](jrct.niph.go.jp/en-latest-detail/jRCTs041210154)). All patients and/or guardians signed written informed consent. Eightyfive pediatric oncology centers across Japan participated inpatient recruitment, treatment administration, follow-up, and data reporting. Our protocol paper12 elaborated on the trial protocol details. Eligibility criteria were patients (i) aged ≤25 years, (ii) receiving allo-HCT for CD19-positive B-ALL beyond the first CR (patients in the second CR were included starting March 2023 after the central review board approval), (iii) Eastern Cooperative Oncology Group performance status of ≤

FAQs

What population and disease setting was studied in SCT-ALL-BLIN21?

CAYA with CD19-positive relapsed or refractory B-cell acute lymphoblastic leukemia who underwent allogeneic HCT beyond first complete remission were enrolled.

How was blinatumomab administered in the posttransplant maintenance setting?

Two courses of 4 weeks each were delivered as continuous intravenous infusion over 4 weeks with a 2-week interval between courses.

What were the main phase I adverse events and reasons for discontinuation?

Grade 4 adverse events were primarily hematologic toxicities, especially lymphocytopenia and neutropenia. Treatment was discontinued due to increased transaminase, grade 3 acute GVHD, and grade 4 neutropenia.

Sep 29, 2026

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