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Abstract The conventional intensity of chemotherapy has reached its limit. Despite the efficacy of blinatumomab in B-cell acute lymphoblastic leukemia (B-ALL) adults with measurable residual disease (MRD) has been proved, studies in children with MRD positivity (MRD+) are still lacking. We conducted an exploratory trial of 14 days of blinatumomab monotherapy in combination with a B-ALL chemotherapy protocol in pediatric patients with MRD+ at the day 46 and evaluated the early efficacy and safety of this approach (Blin-14d-therapy, ChiCTR2100053318, registered on 11/18/2021). Totally 9 pediatric patients were included in Blin-14d group and 38 in non-Blin-14d group. After monotherapy with blinatumomab, all evaluable patients became MRD negative in Blin-14d group and achieved MRD conversion earlier than conventional chemotherapy group, predicting better treatment outcomes. Compared to previous investigations, the incidence of AEs was lower and MRD clearance was higher in this study. In conventional blinatumomab studies, a single course was administered for 28 days. T-cell counts continued to trend upward from day 14 to 21, whereas a downward trend was observed from day 21 to 28, suggesting that T-cell exhaustion occured. While in our regimen, blinatumomab was administered for 14 days, and T-cell levels still had an upward trend in the first week after the end of the infusion, suggesting that T-cell exhaustion at this time was not significant and anti-tumor effect prolonged. Initial data from this study demonstrate that Blin-14d-therapy with chemotherapy has encouraging clinical activity and a manageable safety profile in pediatric patients with day46 MRD+ B-ALL in IR/HR groups.
Xue et al. (Fri,) studied this question.