Abstract P067

Fragmentomics analysis to enhance ctDNA based risk stratification in Hodgkin Lymphoma

Background: Current clinical challenges in Hodgkin lymphoma (HL) include long-term treatment-related toxicities and relapsed/refractory disease. Up to now, risk stratification tools mainly rely on clinical characteristics and lack sensitivity. Recent studies, including ours, demonstrated that circulating tumor (ct)DNA sequencing offers the potential to overcome this limitation.

Aims: We aim to increase the sensitivity to distinguish tumor (ctDNA) from non-tumor derived cell-free (cf)DNA and thus refine detection of minimal residual disease (MRD) (Sobesky, Med, 2021; Heger, J Clin Oncol, 2024; Heger, Blood, 2026) by incorporating fragmentomics analysis.

Methods: We developed a software tool to extract advanced fragmentomics data at the read level and incorporate mutational information. The tool was applied to 154 plasma samples from 71 patients with previously untreated HL (sampled from the HD21 trial) and 10 healthy controls.

Results: We found significant differences in cell-free DNA fragment length distribution between pre-treatment HL samples and healthy controls (mean 180 vs. 200bp, Mann-Whitney U test, p<0.01). Interestingly, fragment length increased with more treatment applied, ultimately approximating healthy controls (healthy control=200bp; pre-treatment=180bp; mid-treatment=185bp; end-of-treatment=187bp). Not only is this shift noticeable for the mean fragment length but it is also independently present for the peak corresponding to mono-nucelosmal length as well as the second peak (corresponding to di-nucleomal length) when comparing HL samples (Fig 1 (A), pre-treatment (blue; BL), mid-treatment (yellow;2CX), and end-of-treatment (grey; EOT)) to healthy controls (red; ctrl). We found that shorter mean fragment length (<182bp) in pre-treatment HL samples was associated with shorter progression free survival (PFS) (Logrank P-value <0.01). Further results will be presented at the meeting.

Conclusion: Fragmentomics analysis in our HL cohort showed shorter mean pre-treatment fragment length compared to healthy controls, with shorter mean length associated with inferior PFS. These findings suggest a potential use of fragment size and other fragmentomic features for dynamic risk stratification in patients with HL.