Early measurable residual disease dynamics and B cell receptor reconstitution following venetoclax and obinutuzumab in chronic lymphocytic leukemia
In chronic lymphocytic leukemia, measurable residual disease (MRD) depth following fixed-duration treatment is associated with progression-free survival (PFS). Often, MRD is reported as a static parameter, but successive MRD measurements may more accurately capture MRD dynamics and reveal valuable prognostic information. We used our recently developed IGHV leader-based NGS assay to measure MRD at four timepoints in 60 patients treated in the HOVON-139/GIVE trial, in which previously untreated patients received one year induction treatment with obinutuzumab and venetoclax, followed by randomization to consolidation treatment with venetoclax or MRD-conditional consolidation. Induction treatment resulted in MRD undetectability (<10-5) in 93% of assessed patients, with 85% and 74% of patients retaining MRD undetectability at six and twelve months after randomization. Uniquely, we measured MRD at a very early timepoint, during the fourth week of venetoclax ramp-up after obinutuzumab pre-induction. Here, MRD levels showed large interindividual variation, and, importantly, were associated with the probability of achieving MRD undetectability after induction treatment, MRD conversion after randomization and PFS. Additionally, the IGHV leader-based NGS assay allows characterization of the healthy background IGHV repertoire. Of note, venetoclax consolidation treatment, compared to no consolidation treatment, significantly impaired polyclonal IGHV repertoire reconstitution after induction treatment with venetoclax and obinituzumab. Overall design: B-cell receptor immunoglobulin heavy chain gene repertoire sequencing of post-treatment samples from CLL patients enrolled in the HOVON139/GIVE trial