Abstract P117

Association of prior PD-1 inhibitor exposure with pre-engraftment syndrome after ASCT in relapsed/refractory Hodgkin lymphoma

Background: PD-1 inhibitors are increasingly incorporated into salvage treatment strategies before autologous stem cell transplantation (ASCT) in relapsed/refractory Hodgkin lymphoma (R/R HL). However, inflammatory complications during the early peri-transplant period remain insufficiently characterized. We evaluated inflammatory events after ASCT, focusing on engraftment syndrome (ES)-like manifestations occurring before neutrophil recovery.

Methods: We retrospectively analyzed 64 consecutive adult HL patients undergoing ASCT at a single center between 2018 and 2025. ES was assessed according to Spitzer and Maiolino criteria. ES-compatible manifestations developing before neutrophil engraftment were classified as pre-engraftment syndrome (pre-ES). Clinically significant events were defined as inflammatory episodes requiring systemic corticosteroid treatment after exclusion of infection.

Results: Conventional ES after ASCT was infrequent. No patient fulfilled Spitzer criteria within the standard engraftment period, while three patients (4.7%) met Maiolino criteria without requiring corticosteroid therapy. When the conventional engraftment timeframe was disregarded, pre-ES manifestations were identified in 34 patients (53.1%) according to Maiolino criteria, although most cases were mild and self-limiting. Three patients developed steroid-requiring pre-ES; each fulfilled Spitzer criteria outside the standard engraftment window. All severe pre-ES cases occurred exclusively in patients previously exposed to PD-1 inhibitors. Prior PD-1 inhibitor therapy was significantly associated with steroid-requiring pre-ES (P=0.0007), although interpretation is limited by the small number of events. Patients with severe pre-ES also exhibited higher early post-transplant CRP levels.

Conclusions: While classical ES after ASCT in HL was uncommon, pre-ES manifestations were frequent. Steroid-requiring pre-ES occurred exclusively in PD-1–exposed patients, suggesting a distinct inflammatory phenotype in this setting. Early recognition and prompt corticosteroid treatment after exclusion of infection may help prevent severe complications. Prospective studies are warranted to better define risk factors, underlying mechanisms, and optimal monitoring strategies in this high-risk population.