Abstract P131

Autologous Stem Cell Transplantation after Anti-PD-1 Therapy in Heavily Pretreated Patients with Relapsed/Refractory Classical Hodgkin Lymphoma: Real-World Outcomes

Background: Autologous stem cell transplantation (ASCT) after anti-PD-1 therapy is an effective option in relapsed/refractory classical Hodgkin lymphoma (cHL). However, real-world outcomes often diverge from clinical trials, as patients are heavily pretreated and frequently undergo ASCT in the ≥3rd-line setting. This study provides real-world data from our clinical practice. Aims: To evaluate ASCT outcomes after anti-PD-1-based regimens in the entire cohort and the ≥3rd-line subgroup (ASCT after anti-PD-1 in the ≥3rd-line setting), identify prognostic factors for PFS, and characterize relapse patterns.

Methods: We retrospectively analyzed patients with cHL who underwent ASCT after anti-PD-1-based regimens (2018–2024). Patients receiving salvage therapy between anti-PD-1 and ASCT were excluded. Survival was estimated using Kaplan-Meier method. Prognostic factors included: number of prior lines of therapy, time interval from anti-PD-1 to ASCT (<60 vs ≥60 days), and refractory status to the pre-anti-PD-1 line. Results: A total of 112 patients were analyzed (median age 35 years, range 19–56). The median number of prior lines of therapy was 2 (range, 2–7). Prior to anti-PD-1, 58%, 34%, and 15% of patients were refractory to 1, 2, and 3 consecutive lines, respectively. Anti-PD-1 was administered as monotherapy (37.5%) or with chemotherapy (62.5%). The median number of anti-PD-1 cycles was 6 (range, 2–52).

Pre-ASCT Responses: complete response (CR) (83%), partial response (PR) (12.5%), progressive disease (0.9%) and indeterminate response (3.6%). Conditioning regimens: BEAM (20%) and BeEAC (80%). Post-ASCT maintenance: brentuximab vedotin (13.4%) and anti-PD-1 (15.1%). At a median follow-up of 37 months (range, 1–91), 3-year OS and PFS were 90% and 77% for the entire cohort (Figure 1). In the ≥3rd-line subgroup, 3-year OS and PFS were 90% and 78%. No prognostic factors significantly impacted PFS in the entire cohort. However, in the ≥3rd-line subgroup, refractory status to the pre-anti-PD-1 line was associated with shorter PFS (3-year PFS 64% vs 85%; p=0.02). A total of 14 relapses occurred, with 13 within 18 months of ASCT (range, 4–24 months). All relapsing patients had pre-ASCT CR or PR.

Conclusion: ASCT after anti-PD-1 demonstrates high effectiveness for heavily pretreated patients in routine practice. In the ≥3rd-line subgroup, refractory status to the pre-anti-PD-1 line was associated with shorter PFS. Most relapses occurred within 18 months post-ASCT.