A study of 78 patients with relapsed/refractory B-cell acute lymphoblastic leukemia (ALL) found that minimal residual disease (MRD) assessment is predictive of survival after salvage treatment and subsequent HCT.
All patients enrolled in the study achieved a morphologic response during either salvage 1 (S1; n=46) or salvage 2 (S2; n=32). MRD assessment was done by multiparameter flow cytometry at the time of remission.
MRD negative status was achieved in 41 of 78 patients (53%). The MRD- rate was 57% in S1 and 47% in S2. Among patients in S1, MRD- status was associated with better 2-year event-free survival (EFS) than those with MRD+: 46% vs. 17%, respectively; (p=0.06). Among MRD- patients who underwent hematopoietic cell transplantation (HCT), EFS and overall survival (OS) were superior in those who underwent HCT in S1 rather than S2 (p=0.003 and p=0.04, respectively). MRD- patients in S1 who subsequently underwent HCT had the best outcomes, with a 2-year OS rate of 65%.
The researchers concluded that a majority of patients with relapsed/refractory ALL who achieve MRD- status in S1 can achieve long-term survival, and that patients transplanted in S2 generally have poor outcomes, regardless of their MRD status.