Molecular Detection of Minimal Residual Disease Precedes Morphological Relapse and Could be Used to Identify Relapse in Pediatric and Young Adult B-Cell Acute Lymphoblastic Leukemia Patients Treated with Tisagenlecleucel

ConclusionsTo examine the comparability of flow cytometry and Ig NGS methods in assessing MRD, baseline and post-treatment samples were tested. Baseline samples, which had a high disease burden, showed 100% MRD concordance between both assays. However, post-treatment, where the leukemic burden was dramatically reduced, Ig NGS detected a greater number of MRD positive samples compared to FC, at each sensitivity level tested (10-4, 10-5 and 10-6). At the highest sensitivity level of 10-6, Ig NGS was able to detect 18% more MRD positive post-treatment samples. Importantly, Ig NGS was able to detect MRD positivity 1-4 months ahead of clinical relapse in a small number of relapsed patients, whether relapse was CD19+ or CD19-. This may provide an important window of opportunity for pre-emptive treatment while a patients' tumor burden is still low.In B-ALL, it has previously been described that MRD levels can be one to three logs lower in blood compared to bone marrow (VanDongen JJ et al. Blood 2015). Our results support these findings whereby MRD burden in bone marrow was higher than in blood using both FC and Ig NGS. We next set out to determine if the increased sensitivity afforded by the Ig NGS assay could provide a level of MRD detection in the blood comparable to FC in the bone marrow. In patients with matching data available, Ig NGS was able to detect more MRD positive blood samples than FC MRD positive bone marrow samples. This suggests that monitoring of MRD using Ig NGS in...
Source: Blood - Category: Hematology Authors: Tags: 618. Acute Lymphoblastic Leukemia: Biology, Cytogenetics, and Molecular Markers in Diagnosis and Prognosis: Poster I Source Type: research