The application of rituximab during the conditioning regimen prevents Epstein - Barr virus infection following rATG-based haploidentical hematopoietic stem cell transplantation in the era of letermovir for cytomegalovirus prophylaxis.

BACKGROUND

In the era of letermovir for cytomegalovirus (CMV) prophylaxis, several centers reported that the incidence of Epstein-Barr virus (EBV) infection were significantly increased.

OBJECTIVE

To investigate the efficacy and safety of rituximab administration during conditioning regimen following haploidentical hematopoietic stem cell transplantation(haplo-HSCT)in the prevention of post-transplant EBV infection.

METHODS

We conducted a retrospective analysis of 100 patients with acute leukemia or myelodysplastic syndrome who underwent haplo-HSCT. Patients in observation group(R group) received rituximab (375 mg/m²) on day -3 before transplantation due to the presence of donor-specific antibody (MFI ≥ 2000) (n = 25) and patients in control group (C group) did not receive rituximab (n = 75) and donor-specific antibody was low (MFI < 2000). The primary objectives were the incidence of EBV-DNA viremia and PTLD within one-year post-transplantation. Secondary objectives included the incidence of CMV infection, cumulative incidence of acute graft-versus-host disease (aGVHD) and chronic GVHD, 100-day non-relapse mortality (NRM), progression-free survival (PFS), and overall survival (OS).

RESULTS

No significant differences were observed in baseline characteristics between the two groups except for primary disease. When compared with the C group, patients in R group exhibited a lower cumulative incidence of EBV viremia within one-year post - transplantation (4.00% vs. 22.67%, P = 0.049) and a lower incidence of aGVHD (28% vs. 50.67%, P = 0.048). There was a trend toward reduction of PTLD in the R group compared with C group (0% vs. 10.67%, P = 0.089).There were no significant differences of the incidence of CMV viremia (24% vs. 13.33%, P = 0.208), cGVHD (16% vs. 12%, P = 0.607), and 100 - day NRM (4.0% vs. 10.67%, P = 0.313) between two groups. The 2-year OS rates in the R group and C group were 83.8% ± 0.086% and 81.9% ± 0.050% respectively (P = 0.360). The 2-year PFS rates in the R group and C group were 83.8% ± 0.086% and 72.6% ± 0.068% respectively (P = 0.360).

CONCLUSION

The combined use of rituximab during the conditioning regimen may be regarded as an effective strategy for preventing EBV reactivation after rATG - based haplo - HSCT in the era of letermovir for CMV prophylaxis.Prospective randomized controlled trials are still required to further validate the reliability of the results.