Abstract P089

Real-world implementation of a modified PET-adapted HD17 approach in early-stage Hodgkin lymphoma: a single-centre audit

Background: Intermediate risk classical Hodgkin lymphoma (HL) has excellent outcomes,but radiotherapy (RT) contributes to late toxicity. The GHSG HD17 trial demonstrated that RT can be omitted in PET4-negative patients after escalated BEACOPP×2 and ABVD×2. We evaluated real-world feasibility, safety and early outcomes of a PET-adapted HD17 approach at University College London Hospital using an interim PET2 (iPET2) in a subgroup of patients and substituting procarbazine with dacarbazine.

Methods: We retrospectively evaluated patients with early-stage HL treated with an HD17-based approach between August2022 and September2025.Patients received escalated BEACOPDac×2 followed by iPET2,performed according to multidisciplinary team decision, with aim to avoid RT.Deauville scores 1–3 were considered negative(neg) ),in contrast to the HD17 trial definition of Deauville scores 1–2 as negative,and 4–5 positive(pos).End-of-treatment(EoT)PET4 response, RT use, toxicity, relapse and survival were reviewed to 1 April 2026.

Results: 40 patients were included;median age was 23.5 years.39 had intermediate-stage disease and 1 had early favourable disease but was treated with this approach to avoid RT for mediastinal disease.iPET2 was performed in 28/40 patients(70%):23/28 (82%) were PET2-neg and de-escalated to ABVD×2, all achieving PET4 complete metabolic response (CMR).5 were PET2-pos;2 received additional escalated BEACOPDac×4(HD18 approach),both were EOT PET-pos and 1 required salvage chemotherapy to CMR. 3 PET2-pos patients de-escalated to ABVD×2; 2 achieved PET4 CMR,1 was PET4-pos and received RT to CMR.12 patients did not undergo iPET2;all followed standard HD17 approach,with 1 PET4-positive patient requiring RT to CMR. Overall, PET4 CMR was achieved in 36/40 patients(90%) including 26/28patients(93%) who underwent iPET2.PET4 positivity was confined to mediastinal disease and occurred mainly in the iPET2-pos group.Post-EoT RT was delivered to 1/28 patients(4%) undergoing iPET2 and 2/40 patients(5%) in total cohort.Grade 3–4 toxicity occurred in 20/40 patients, predominantly during escalated BEACOPDac.With median follow-up of 17 months, 39/40 patients were in CMR,1 relapsed and overall survival was 100%.

Conclusion: PET-adapted HD17 management achieved high EoT PET negativity with minimal RT use:no iPET2-neg patients were PET4-pos, while 96% avoided RT and 93% achieved PET4 CMR.iPET2 may identify high risk patients in whom HD18 approach can be a RT sparing alternative.