Efficacy and safety of ruxolitinib for graft-versus-host disease prophylaxis in patients with aplastic anemia undergoing PBSC-only allogeneic stem cell transplantation: a prospective phase II study.

Abstract

Background: While peripheral blood hematopoietic stem cell transplantation (PB-HSCT) supports rapid engraftment and reduces graft failure risk in aplastic anemia (AA) patients, it compromised higher risk of acute graft-versus-host disease (aGVHD), highlighting the need for more effective prophylactic strategies. This phase II clinical trial was designed to assess the efficacy and safety of ruxolitinib, a JAK1/2 inhibitor, as part of GVHD prophylaxis regimen following PB-HSCT.

Methods: This open-label, single-arm, Phase II clinical trial (ClinicalTrials.gov: NCT05914714) enrolled patients with AA between June 2023 and December 2024. Ruxolitinib was initiated at the start of conditioning and continued for 3 months post-transplant at a dose of 5 mg twice daily. A historical control cohort receiving standard GVHD prophylaxis between January 2019 and May 2023 was included for comparison. To address baseline imbalances, propensity score-based inverse probability of treatment weighting (IPTW) was applied. The primary objective was the incidence of aGVHD six months after HSCT. Secondary endpoints included one-year overall survival (OS) and GVHD-free, failure-free survival (GFFS). Immune reconstitution-including T cells, B cells, NK cells-and levels of pro-inflammatory cytokines were also evaluated to explore potential mechanisms.

Results: A total of 82 patients were enrolled (ruxolitinib group n = 46, historical control cohort n = 36). Comparative analysis showed that ruxolitinib significantly reduced the cumulative incidence of grade II-IV aGVHD (HR 0.24; p = 0.004) and severe aGVHD (0% vs 15.8%; p = 0.008) compared with the control group. At a median follow-up of 417 days (range: 112-725), the ruxolitinib group demonstrated significantly superior 1-year GFFS (91.6% vs. 72.1%; HR 0.23, weighted log-rank p = 0.012). Notably, the ruxolitinib group not only exhibited more rapid recovery of CD4 + Tregs at 3 months post-HSCT. Notably, but also suppressed proinflammatory cytokine levels during engraftment.

Conclusions: The peri-transplantation addition of ruxolitinib to the standard GVHD prophylaxis regimen in PB-HSCT for AA patients has shown to be a safe and effective approach to reducing both the incidence of aGVHD, while improving patient outcomes. Our study suggests that ruxolitinib may offer a promising strategy for improving survival and immune recovery. Trial registration clinicaltrials.gov identifier: NCT05914714.