The EORTC-1537-COBRA trial investigated the efficacy of very early FDG-PET/CT response-adapted therapy in patients with advanced-stage Hodgkin lymphoma using brentuximab vedotin-containing regimens, i.e. brentuximab vedotin, doxorubicin, vinblastine and dacarbazine (A-AVD); and brentuximab vedotin, etoposide, cyclophosphamide, doxorubicin, dacarbazine and dexamethasone (BrECADD). This phase II study enrolled 150 patients, all of whom received an initial cycle of A-AVD, followed by an early PET/CT scan. Patients with negative PET results (Deauville scores 1–3) continued with A-AVD, while those with positive results (scores 4–5) switched to BrECADD. Radiotherapy was given only to those with residual PET positivity after chemotherapy.