Serial circulating tumor DNA sequencing reveals clonal dynamics and can offer treatment guidance in relapsed/refractory diffuse large B‐cell lymphoma (2023)

Introduction: Despite recent advances in the treatment of relapsed/refractory (rr)DLBCL, most patients still face progression and death. Current clinical challenges include allocation of patients to the variety of available treatment options and early detection of insufficient response. While recent evidence suggests utility of circulating tumor (ct)DNA derived biomarkers for CAR-T cell treated patients (Sworder et al, 2023), data on ctDNA in diversely treated rrDLBCL is scarce. Methods: We applied ctDNA sequencing to 197 blood samples of consecutive patients with rrDLBCL presenting at the University Hospitals Cologne and Essen, Germany. An extension of the cohort to >300 samples is ongoing. Samples were analyzed as previously described (Sobesky et al., 2021; Heger et al., 2022). Results: Most patients presented with stage III/IV disease (88.4%), intermediate (58.1%) or high risk (31.4%) international prognostic index (IPI), and received CAR-T cells, high-dose chemotherapy and autologous stem cell transplantation, or other approved treatments. The mean ctDNA concentration at baseline closely correlated with lactate dehydrogenase (LDH) levels (R = 0.61, p < 0.001). Mutations were most frequently detected in IGLL5 (31.4%), KMT2D (30.2%), and TP53 (24.2%), matching previous reports (Chapuy et al, 2018; Meriranta et al, 2022; Sworder et al, 2023). No significant association between the most frequently mutated genes and outcome was observed. When assessing minimal residual disease (MRD) dynamically during and after treatment, we observed significantly impaired progression-free (PFS, p = 0.025) and overall survival (OS, p = 0.019) in MRD-positive patients. In a multivariable model, MRD log10 levels had a significant impact on PFS (HR 1.52, 95% CI: 1.12–2.07, p = 0.007) and OS (HR 1.75, 95% CI: 1.10–2.78, p = 0.018), while LDH, IPI and ctDNA concentration at baseline did not (Figure 1). In patients with ≥5 samples available, assessment of clonal evolution revealed at least two different patterns of clonal dynamics—one consisting of reemergence of a largely similar clone at relapse and one reflecting expansion of one or more subclones acquiring novel genetic lesions, such as TP53 mutations. Examining clonal evolution in the context of treatment choices revealed subclone-specific treatment effects. For example, in a patient with chemo-resistant disease, CAR-T cells were able to eliminate all but one clone. Intriguingly, this clone drove early progression of disease but was successfully overcome by allogeneic stem cell transplantation. The research was funded by: J.M.H. was supported by a MD Research Stipend of the Else Kröner Forschungskolleg Clonal Evolution in Cancer, University Hospital Cologne, Cologne, Germany. Sequencing infrastructure was supported by DFG Research Infrastructure as part of the Next Generation Sequencing Competence Network [INST 216/981-1], and next-generation sequencing (NGS) analyses were carried out at the production site WGGC Cologne. The research was partly funded by grants BO5316/3-1 and BO5316/2-1 from the Deutsche Forschungsgemeinschaft (DFG) as well as a grant by the Frauke Weiskam, Christel Ruranski Foundation, and Else Kröner Fresenius Stiftung (Kolleg, 2016). Keywords: Aggressive B-cell non-Hodgkin lymphoma, Liquid biopsy, Minimal residual disease Conflicts of interests pertinent to the abstract. J. M. Heger Consultant or advisory role: Miltenyi Research funding: Incyte; Novartis Educational grants: Kite-Gilead, Novartis B. von Tresckow Consultant or advisory role: Allogene, BMS/Celgene, Cerus, Incyte, Miltenyi, Novartis, Pentixafarm, Roche, Amgen, Pfizer, Takeda, Merck Sharp & Dohme, Gilead Kite Research funding: Novartis, Merck Sharp & Dohme, Takeda Educational grants: AbbVie, AstraZeneca, Kite-Gilead, Merck Sharp & Dohme, Takeda, Novartis S. Borchmann Consultant or advisory role: Galapagos Stock ownership: Liqomics