Serum thymus and activation-regulated chemokine level monitoring may predict disease relapse detected by pet scan after reduced-intensity allogeneic stem cell transplantation in patients with Hodgkin lymphoma

Patients with relapsed and refractory Hodgkin lymphoma (HL) may experience long-term survival after allogeneic stem cell transplantation (alloSCT), but disease recurrence represents the main cause of treatment failure. Positron-emission tomography (PET)-positive patients after alloSCT have a dismal outcome. Serum thymus and activation-regulated chemokine (TARC) is produced by Reed-Sternberg cells and may be a marker of disease. Our study aimed at assessing whether TARC levels after alloSCT correlated with disease status and whether TARC monitoring could increase the ability to predict relapse. Twenty-four patients were evaluated in a prospective observational study. TARC serum level and PET were assessed before and after alloSCT during the follow-up (median, 30 months; range, 2 to 54). Before alloSCT, the median TARC level was 721 pg/mL (range, 209 to 1332) in PET-negative patients and 2542 pg/mL (range, 94 to 13,870) in PET-positive patients. After alloSCT, TARC was 620 pg/mL (range, 12 to 4333) in persistently PET-negative patients compared with 22,397 pg/mL (range, 602 to 106,578) in PET-positive patients (. P < .0001). In 7 patients who relapsed after alloSCT, TARC level increased progressively even before PET became positive, with a median fold increase of 3.19 (range, 1.66 to 7.11) at relapse. The cut-off value of 1726 pg/mL had a sensitivity of 100% and a specificity of 71% for PET positivity. Patients with at least 1 TARC value above 1726 pg/mL during the first year after alloSCT had a worse progression-free survival (. P= .031). In conclusion, TARC was correlated with disease status and its monitoring may be able to predict PET positivity after alloSCT, thus potentially allowing an early immune manipulation.