Leukemia Burden Impacts the Efficacy and Toxicity of Blinatumomab in Pediatric B-Cell Acute Lymphoblastic Leukemia

Blinatumomab has been approved for the treatment of pediatric B-cell acute lymphoblastic leukemia (B-ALL). This study aimed to investigate the association between leukemia burden and the efficacy of blinatumomab in real-world applications.

A real-world study was conducted by enrolling patients aged 0-18 years who were diagnosed with CD19-positive B-ALL and treated with blinatumomab between January 2021 and May 2023 from 14 centers in China.

A total of 304 patients were enrolled in this analysis. In the patients with > 5% blasts before blinatumomab (non-complete remission, NCR group), 75.9% achieved complete remission (CR) and 69.0% of the NCR patients achieved minimal residual disease (MRD) negativity. Among the patients with ≤ 5% blasts but multiparametric flow cytometry MRD (MFC MRD) positive (MRD+ group), 98.9% achieved MRD negativity. Of the MFC MRD negative patients (MRD- group), the quantitative polymerase chain reaction MRD (qPCR MRD) and next-generation sequencing MRD (NGS MRD) clearance rate was 60.0% (12/20) and 65.5% (19/29), respectively. Additionally, patients in the MRD- and MRD+ groups had significantly better outcomes than those in the NCR group, with 30-month overall survival (OS) rates of 95.3% (95% CI: 91.4%-99.3%), 91.2% (95% CI: 85.0%-97.8%), and 77.6% (95% CI: 67.4%-89.4%), respectively (p < 0.001), and 30-month event-free survival (EFS) rates of 93.9% (95% CI: 89.6%-98.3%), 90.8% (95% CI: 85.0%-97.1%), and 56.7% (95% CI: 41.0%-78.6%), respectively (p < 0.001). In this study, 41.4% of patients experienced grade ≥ 3 adverse events (AEs), with hematological toxicity being the most common (33.2%). The severe adverse events, such as cytokine release syndrome (CRS) and neurotoxicity, occurred at a low rate, particularly grade ≥ 3, at 3.6% and 2.6%, respectively.

Overall, these results indicate that blinatumomab is effective and well tolerated. Patients with a lower leukemia burden before blinatumomab administration tend to have better OS and EFS with fewer AEs.