Introduction: Positron emission tomography (PET) is an available tool to adapt treatment strategy in newly diagnosed classical Hodgkin Lymphoma (HL). However, approximately 15% of patients (pts) with negative interim PET (iPET) still experience relapse. Here, we aimed at correlating PET-variables, namely metabolic tumor volume (MTV) and total lesion glycolysis (TLG), with serum TARC (sTARC), a promising predictor of response in HL.
Methods: We prospectively collected plasma samples of 58 untreated HL pts, stratified according to GHSG risk categories and treated according to a PET-driven strategy. Samples were collected at baseline, after 2 cycles of ABVD (coinciding with iPET), and at the end of treatment (EOT). All pts underwent PET scan at the same timepoints. Thresholds used for measuring MTV and TLG were SUVmax>2.5 and 41% of the SUVmax. Deauville ≤3 defines complete remission. To assess interim response, variables were evaluated as logarithmic reduction (LogRED) of baseline vs iPET, and as logarithmic variation (Log∆) of EOT vs iPET for EOT response.
Results: Overall, 45 out of 58 pts were evaluable. We excluded 12 pts due to unavailable PET scan at any timepoint, and 1 for missing samples. Median age was 33 years (17–58), 60% pts were male, 58% pts had B-symptoms and 71% were diagnosed with an advanced stage (IIB, III, IV). Five (11%) pts were iPET+ and 5 (11%) were EOT-PET+. Results of LogRED and Log∆ for TLG 2.5, TLG 41%, MTV 2.5, MTV 41% and sTARC in both iPET- and iPET+ pts are listed in Table 1 and Table 2, respectively. Overall, LogRED of PET variables were significantly lower in iPET+ compered to iPET- pts (p<.001), while no differences were observed for LogRED of sTARC (p=.4). In EOT+ pts, the Log∆ for both PET-variables and sTARC was significantly different (p<.001). The correlation between PET variables and sTARC showed a significant trend for LogRED using the 2.5 threshold for MTV and TLG (respectively, r=.333, p=.026 and r=.304, p=.042), but not for the 41% cut-off (r=.298, p=.052 and r=.268, p=.083). Log∆ between PET-variables vs sTARC were significantly correlated (r=.427, p=.004 for TLG 2.5, r=.404, p=.007 for TLG 41%, r=.427, p=.004 for MTV 2.5 and r=.401, p=.008 for MTV 41%).
Conclusion: Our findings show that the PET scan and sTARC are intercorrelated predictors in HL, with the latter potentially being a helpful marker for identifying iPET-/EOT-PET+ pts. Larger studies are needed to confirm the role of sTARC monitoring.