Low leukemia burden improves blinatumomab efficacy in patients with relapsed/refractory B‐cell acute lymphoblastic leukemia
Queudeville M., Stein AS., Locatelli F., Ebinger M., Handgretinger R., Gökbuget N., Gore L., Zeng Y., Gokani P., Zugmaier G., Kantarjian HM.
AbstractBackgroundA 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.MethodsData 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.ResultsData 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.ConclusionAny bBMB% <50% was associated with improved efficacy following blinatumomab treatment for R/R B‐ALL.