Concordance of measurable residual disease (MRD) rates in the peripheral blood and bone marrow after first-line treatment for CLL with targeted agents: A systematic review and meta-analysis.

Abstract

e19023 Background: Undetectable measurable residual disease (uMRD) is associated with prolonged progression free survival in patients with chronic lymphocytic leukemia (CLL) (Rios-Olais et al., 2024). Peripheral blood (PB) MRD testing is less invasive and allows more frequent MRD monitoring than bone marrow (BM) MRD testing. As MRD testing and MRD-guided time-limited therapies become more common, there is a need to determine the concordance between rates of uMRD in the PB and BM. Methods: We performed a systematic review and meta-analysis of studies in CLL to determine the concordance between rates of uMRD in the PB and BM. Prospective clinical trials evaluating first-line, time-limited treatment of CLL with targeted agents or anti-CD20 monoclonal antibodies (mAbs) were identified via searches of PubMed, Embase, Scopus, and Web of Science from inception until December 15 th , 2025. Studies were included if they reported rates of BM and PB uMRD at the same timepoint using the same method of MRD testing. Study arms evaluating chemotherapy, single-agent targeted therapy or single-agent anti-CD20 mAbs were excluded. Study sample size, number of patients receiving MRD testing, rates of uMRD in PB and BM, time and method of MRD testing, depth of MRD testing, and treatment arm were extracted. The agreement of uMRD rates between PB and BM was assessed using intraclass correlation coefficients (ICC). Results: 3128 studies were identified on initial search. After study selection criteria were applied, 24 timepoints across 12 prospective clinical trials were analyzed. Across all timepoints, 3121 PB and 2782 BM MRD measurements were included. All timepoints defined uMRD at a depth of under 0.01% CLL cells (10^-4). 20/24 timepoints utilized flow cytometry for MRD testing, 3 utilized allele-specific oligonucleotide PCR (ASO-PCR), and one utilized next-generation sequencing (NGS). 8 timepoints evaluated patients treated with a BTK inhibitor + venetoclax, 10 evaluated patients treated with venetoclax + an anti-CD20 mAb, and 6 evaluated patients treated with triplet therapy. The ICC between rates of uMRD in PB and BM was 0.925 (95% CI: 0.89, 0.95), indicating an excellent degree of agreement between the two methods of testing.(Koo & Li, 2016) The mean uMRD rates in PB and BM were 70.1% and 64.3%, respectively. The mean rate of uMRD in the PB was 5.87% (95% CI: -7.05, 18.80%) higher than in the BM; indicating a consistent slight bias of higher PB uMRD rates compared to BM across timepoints. Conclusions: Overall, we demonstrate that in patients with CLL treated with modern, time-limited therapy, there is high concordance in uMRD rates between PB and BM. Rates of uMRD in the PB are typically slightly higher than in BM.