Molecular profiling of cell-free DNA from classic Hodgkin lymphoma patients identifies potential prognostic clusters and corresponds with disease dynamics

Cell-free DNA (cfDNA) analysis has advantages over tissue analysis for molecular profiling of classic Hodgkin lymphoma (cHL) at diagnosis and offers additional opportunities for sensitive non-invasive disease tracking during treatment. The aim of this study is to correlate cfDNA based molecular profiling with disease characteristics including serum Thymus and Activation Regulated Chemokine (TARC) levels and FDG-PET imaging, which are established markers of disease assessment. cfDNA isolated from plasma samples of 42 cHL patients was analyzed using low coverage whole genome and targeted next-generation sequencing. Patients were clustered in three groups based on Epstein-Barr virus (EBV) and SOCS1 mutational status. Patients in the EBV-negative (EBV-) & SOCS1 mutated (m) cluster had more extensive disease based on significantly higher serum TARC (sTARC) levels, higher metabolic tumor volume and increased risk of treatment failure. Additionally, the median variant allele frequency and mutational load was highest in the EBV- & SOCS1m cluster, which was validated in two external cohorts. The estimated tumor fraction and median variant allele frequency of the single nucleotide variants correlated with sTARC levels. Disease tracking over time demonstrated cfDNA level dynamics that partly resembled sTARC levels and imaging results. In conclusion, we show that cfDNA based clustering on EBV status and SOCS1 mutational status correlates with adverse disease characteristics and increased risk of treatment failure. CfDNA-based disease tracking has the potential to serve as a sensitive tool that can complement existing response assessment methods in cHL patients.