Puhlmann, Markus

7503 Background: To date, an overall survival (OS) benefit from upfront treatment for new treatment combinations over existing approaches has rarely been shown in first-line classical Hodgkin lymphoma (cHL). With the introduction of newer active therapies for relapsed/refractory disease, demonstration of improved OS with first-line therapy has been challenging. In ECHELON-1 (NCT01712490), 5-year follow-up analyses supported the long-term progression-free survival (PFS) benefit with first-line brentuximab vedotin, doxorubicin, vinblastine, and dacarbazine (A+AVD) vs doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) in patients (pts) with stage III/IV cHL, independent of interim positron emission tomography status. A+AVD had a manageable long-term safety profile, with numerically fewer second malignancies and a greater number of pregnancies reported vs ABVD (Connors et al, NEJM 2018; Straus et al, Lancet Haematol 2021). We report a prespecified OS analysis after approximately 6 years’ follow-up (cut-off, June 1, 2021). Methods: Pts were randomized 1:1 to receive up to 6 cycles of A+AVD (n = 664) or ABVD (n = 670) on day 1 and 15 every 28 days. OS was the key secondary endpoint and was an event-driven, pre-specified, alpha-controlled analysis in the intention to treat population. Results: At a median follow-up of 73 months, 39 and 64 OS events occurred in A+AVD and ABVD arms, respectively: OS significantly favored A+AVD vs ABVD (HR 0.590; 95% confidence interval [CI] 0.396–0.879; p = 0.009). Estimated 6-year OS rates (95% CI) were 93.9% (91.6–95.5) vs 89.4% (86.6–91.7) with A+AVD vs ABVD, respectively. There was a consistent OS benefit for A+AVD vs ABVD across prespecified subgroups. The 6-year PFS estimate was 82.3% (79.1–85.0) vs 74.5% (70.8–77.7) with A+AVD vs ABVD, respectively (HR 0.678 [95% CI 0.532–0.863]). Overall, A+AVD had a comparable long-term safety profile to ABVD. Treatment-emergent peripheral neuropathy continued to resolve or improve in both arms, with 86% (379/443) and 87% (249/286) of cases in the A+AVD and ABVD arms either completely resolving (72% vs 79%) or improving (14% vs 8%) by last follow-up. Fewer second malignancies were reported in the A+AVD vs ABVD arm (23 vs 32). More female patients reported pregnancy (49 vs 28) or live births (42 vs 19 in females) in the A+AVD vs the ABVD arm; no stillbirths were reported. No new safety signals were identified. Conclusions: A+AVD treatment resulted in a statistically significant 41% reduction in the risk of death vs ABVD, with a manageable safety profile consistent with prior reports. These outcomes confirm A+AVD as a preferred option for pts with previously untreated stage III/IV cHL. Clinical trial information: NCT01712490.