Impact of minimal residual disease response and of status of disease on survival after blinatumomab in B-cell acute lymphoblastic leukemia: results from a real-life study

: Blinatumomab is a bispecific T-cell engager approved for relapsed/refractory and minimal residual disease positive B-cell Acute Lymphoblastic Leukemia. We conducted a retrospective study evaluating the outcome of Blinatumomab. The impact of clinical and treatment-related variables on cumulative incidence of relapse/progression (CIRP), event-free (EFS) and overall survival (OS) was analyzed. From January 2016 to December 2022 50 Ph'- (37) and Ph+ (13) B-ALL patients received Blinatumomab. The median age was 37. Indications to blinatumomab were relapsed/refractory B-ALL in 29 and MRD-positive in 21 patients. Blinatumomab was the 2nd and 3rd line in 40 and in 10 patients, respectively. Twenty patients were treated pre-transplantation, ten were treated for relapse after transplant, twenty were not eligible for transplant. Out of 29 patients treated for relapsed/refractory disease, 16 (55%) achieved complete response and 12 achieved MRD-negativity. Out of 21 patients treated for MRD, 16 (76%) achieved MRD-negativity. At a median follow-up of 46 months the median EFS and OS were 11.5 and 16.2 months. The CIRP was 50%. In univariate analysis age, disease-status (overt vs. minimal disease) at blinatumomab, bridging to transplant after blinatumomab and MRD-response resulted significant for EFS and OS. In multivariate analysis only disease-status and MRD-response retained significance both for EFS and OS. Disease-status and MRD-response resulted significant for EFS and OS also after censoring at HSCT. This retrospective study on B-ALL patients treated with blinatumomab confirms a superior outcome for MRD-responsive over MRD non-responsive patients. Survival depends also on the disease-status prior treatment.