Longitudinal Circulating Tumor DNA Dynamics During & After First-Line Therapy in a National Cohort of Large B-Cell Lymphomas
EOT MRD using ultrasensitive circulating tumor DNA (ctDNA) assays is predictive of relapse risk (Wang et al. 2025. JCO). Prior studies have shown that molecular response assessment during therapy also holds promise for risk stratification (Kurtz et al., JCO). However, comprehensive real-world data capturing the full longitudinal dynamics are lacking.
We analyzed ctDNA in patients enrolled in HOVON-902, a prospective, multicenter, real-world study of blood-based response monitoring in LBCL patients receiving R-CHOP/DA-EPOCH-R. Plasma samples were collected at up to 11 time points: baseline (C1D1), at interim induction cycles (C2D1, C3D1, C4D1), at EOT, and during surveillance (every 3 months in year 1 and every 6 months in year 2). Patient-specific phased variants (PVs) were identified using PhasED-Seq from FFPE or baseline plasma with matched germline DNA (Foresight CLARITY). PVs were tracked longitudinally to detect MRD at key treatment milestones and to assess previously defined molecular response kinetics in relation to PFS and OS.
We monitored ctDNA MRD in >1000 serial plasma samples from >150 patients with LBCLs (94% DLBCL-NOS, 6% HGBCL). The median age was 68 years (19-88), 66% were male, 80% had advanced-stage disease (III/IV), and 20% had Low, 30% Low Intermediate, 28% High Intermediate, and 22% High IPI risk. At a median follow-up of 37 months (1.4-55.4).
Overall, more patients cleared MRD with each successive cycle during 1L therapy. Specifically, MRD detection decreased over time during induction, with preliminary on-treatment MRD clearance rates of 28%, 51%, 64%, and 81% at C2D1, C3D1, C4D1, and EOT, respectively. MRD status was prognostic at each landmark (P<0.05 for all), but with increasing prognostic value over time. Consistent with the therapeutic effect of additional treatment cycles, outcomes for MRD+ patients at each landmark worsened throughout therapy. Outcomes were also correlated with early ctDNA response kinetics: EMR (2-log10 decrease in [ctDNA]) and MMR (2.5-log10 decrease) were both significantly associated with 3-year PFS. Preliminary results show lack of EMR associated with significantly inferior 3-year PFS (EMR, HR 3.2, 95% CI 1.7-5.9, p < 0.001).
With the addition of surveillance samples, initial results show that 91% of patients with confirmed DLBCL relapse were MRD+ at either the EOT or during follow-up, representing a 17% increase in clinical sensitivity for detecting relapse. Conversely, among patients who did not relapse, 96% had negative EOT MRD, and 99% had either negative EOT MRD or achieved MRD clearance during follow-up.
This is the first real-world study of ctDNA dynamics in a uniformly treated LBCL cohort. Our findings confirm the prognostic value of on-treatment MRD and molecular response assessment. Post-EOT ctDNA monitoring reflects the temporal relationship between tumor burden detection and relapse.