Prior status of graft‐versus‐host disease affects donor lymphocyte infusion outcomes in patients with relapsed haematological malignancies after allogeneic stem cell transplantation

Optimizing the effectiveness of donor lymphocyte infusion (DLI) for relapse after allogeneic stem cell transplantation (alloHSCT) has been challenging. We investigated whether the benefits of achieving full donor chimerism (FDC) and developing graft-versus-host disease (GVHD) after DLI are affected by a history of GVHD before DLI. We retrospectively analysed 56 patients who received DLI for relapse after alloHSCT at our institute from 2015 to 2022. Among 29 patients without GVHD before DLI, those who achieved FDC after DLI had a significantly higher 1-year overall survival (OS) compared to those who did not (73.7% vs. 20.0%; p < 0.001). Furthermore, in the same cohort, patients who developed GVHD after DLI showed a tendency towards higher OS compared to those who did not (60.0% vs. 52.6%; p = 0.067). In contrast, in patients with GVHD before DLI, there was no significant difference in OS between patients with or without achieving FDC (64.3% vs. 33.3%, p = 0.226) or developing GVHD (60.0% vs. 53.3%, p = 0.866). Our study showed that achieving FDC or developing GVHD after DLI improved OS, but only in those without a prior history of GVHD. The graft-versus-leukaemia effect may be better exploited in patients without a history of GVHD.