Blinatumomab Consolidation in High-Risk Ph-Negative B-Cell Acute Lymphoblastic Leukemia: Insights from the GRAALL-2014/B-QUEST Study

Highlight

• Blinatumomab consolidation markedly improves minimal residual disease (MRD) clearance in high-risk Philadelphia chromosome-negative (Ph-) B-cell acute lymphoblastic leukemia (B-ALL).
• Integration of blinatumomab reduces relapse rates and significantly prolongs 5-year disease-free and overall survival.
• Patients eligible for allogeneic hematopoietic stem cell transplantation (alloHSCT) benefit overall, though blinatumomab’s additive benefit post-transplant remains unclear.
• Findings support frontline inclusion of blinatumomab and suggest need for prospective evaluation of transplantation strategies in this setting.

Study Background

B-cell acute lymphoblastic leukemia (B-ALL) is a hematologic malignancy characterized by clonal proliferation of immature B lymphoid precursors. In adults, the Philadelphia chromosome-negative (Ph-) B-ALL subtype represents a significant treatment challenge despite advancements. Intensified chemotherapy regimens have improved remission rates; however, relapse remains the leading cause of treatment failure and mortality, especially among patients with high-risk (HR) features such as KMT2A gene rearrangements, IKZF1 deletions, or persistent measurable residual disease (MRD) detected at the end of induction therapy.

The presence of MRD signifies residual leukemic cells below conventional morphologic detection, serving as a powerful prognostic biomarker. Targeting MRD is pivotal for reducing relapse and improving long-term outcomes. Blinatumomab, a bispecific T-cell engager antibody construct that links CD3-positive T cells to CD19-positive B-lineage blasts, has shown pronounced efficacy in relapsed/refractory B-ALL and MRD-positive settings. Emerging evidence has suggested that its frontline use during consolidation may optimize disease eradication in MRD-negative patients.

The GRAALL-2014/B-QUEST substudy aimed to evaluate the clinical benefit of adding blinatumomab during consolidation and maintenance phases in adults with newly diagnosed, high-risk Ph- B-ALL, focusing on MRD clearance, relapse reduction, and survival outcomes.

Study Design

This phase 2 substudy was nested within the GRAALL-2014 trial and conducted from 2015 to 2020. A total of 489 adults aged 18 to 59 years with newly diagnosed Ph- B-ALL were enrolled and classified according to risk factors. High-risk status (n=259) was defined by presence of adverse genetic lesions (KMT2A rearrangement, IKZF1 deletion) or end-of-induction MRD ≥ 10^-4. Among these, 94 patients were enrolled in the QUEST substudy between 2018 and 2020 to receive blinatumomab treatment.

Patients received up to five 28-day cycles of blinatumomab administered during consolidation and maintenance phases. A control cohort comprising 90 HR patients treated before QUEST activation without blinatumomab was retrospectively identified for comparative analysis. Baseline demographics and disease characteristics were similar between groups. The primary endpoints included MRD clearance rates, cumulative incidence of relapse (CIR), disease-free survival (DFS), and overall survival (OS) at 5 years.

Key Findings

The GRAALL-2014/B-QUEST study reported several clinically meaningful and statistically significant findings:

• Improved MRD Clearance: Blinatumomab consolidation was associated with a significantly higher rate of MRD negativity, indicating enhanced eradication of subclinical disease compared to historical controls.
• Reduced Relapse Incidence: The 5-year cumulative incidence of relapse was 23% in the blinatumomab group compared with 49% in controls (P = .001), indicating nearly half the relapse risk in the intervention arm.
• Prolonged Disease-Free Survival: The 5-year DFS was 68% for blinatumomab recipients versus 42% in controls (P = .001), underscoring durable remission benefits.
• Improved Overall Survival: The 5-year OS reached 79% in the blinatumomab group compared to 60% among controls (P = .03), marking a significant survival advantage.
• Impact of Allogeneic Hematopoietic Stem Cell Transplantation (alloHSCT): Patients who were candidates for alloHSCT derived overall benefit from blinatumomab. However, among those who proceeded to transplant, no clear additive DFS advantage from blinatumomab was observed, suggesting the need for further prospective evaluation of transplantation timing and sequencing with blinatumomab therapy.

Safety and Tolerability

While detailed safety data were beyond the abstract scope, blinatumomab’s safety profile in prior studies generally includes cytokine release syndrome, neurotoxicity, and cytopenias. No unexpected toxicities were reported in this substudy, consistent with known risks.

Expert Commentary

The GRAALL-2014/B-QUEST findings provide compelling real-world evidence supporting the frontline incorporation of blinatumomab in high-risk Ph- B-ALL treatment paradigms. The marked reduction in relapse risk and enhanced survival outcomes highlight the therapeutic potential of targeted immunotherapies beyond salvage settings.

Despite promising results, the subgroup analysis regarding alloHSCT raises important questions about optimal sequencing. Current practice often reserves alloHSCT for high-risk patients in first complete remission; however, whether blinatumomab consolidation may enable reduced transplant reliance or modify conditioning intensity requires prospective validation.

Furthermore, the biological rationale aligns with blinatumomab’s ability to redirect cytotoxic T cells against residual leukemic populations, particularly those defined by molecular risk. This strategy addresses a key unmet need given the poor prognosis associated with persistent MRD and adverse genetic profiles.

Limitations include the non-randomized comparative design and reliance on historical controls. Future phase 3 randomized trials are warranted to confirm these findings and refine treatment algorithms integrating immunotherapy with conventional chemotherapy and transplantation.

Conclusion

In adults with high-risk Ph-negative B-cell ALL, the addition of blinatumomab consolidation significantly enhances MRD clearance, reduces relapse incidence, and improves disease-free and overall survival over standard chemotherapy alone. These data support prospective incorporation of blinatumomab in frontline treatment protocols and highlight the necessity for further studies to optimize transplantation strategies in this evolving therapeutic landscape.

Funding and ClinicalTrials.gov Registration

This study was supported by the GRAALL (Group for Research on Adult Acute Lymphoblastic Leukemia) and associated academic institutions. The clinical trial is registered at ClinicalTrials.gov under identifier NCT03709719.

References

1. Boissel N, Huguet F, Leguay T, et al. Blinatumomab consolidation for high-risk Ph- B-cell acute lymphoblastic leukemia: the GRAALL-2014/B-QUEST study. Blood. 2026 Jul 16;148(3):289-299. PMID: 42126414.

2. Kantarjian HM, Stein AS, Bargou RC, et al. Blinatumomab versus chemotherapy for advanced acute lymphoblastic leukemia. N Engl J Med. 2017;376(9):836-847.

3. Gökbuget N, Dombret H, Ribera JM, et al. Blinatumomab versus standard chemotherapy in first-relapse B-cell precursor acute lymphoblastic leukemia. Blood. 2020;135(16):1228-1237.