Rituximab for Desensitization during HLA-Mismatched Stem Cell Transplantation in Patients with a Positive Donor Specific Anti-HLA Antibody: A Prospective Study

A prospective, clinical trial in non-manipulated haploidentical allografts was initiated to define the efficacy of a single dose of 375 mg/m2 rituximab as a desensitization regimen for donor-specific anti-HLA antibody (DSA)-positive patients with 2,000 ≤ mean fluorescence intensity (MFI) < 10,000. In the clinical cohort, compared to pretransplantation [median, 4791, n=28], the median MFI levels at day 7 [0], 14 [0], 21 [0], 30 [0], and 45 [0] following transplantation were significantly decreased (P<0.0001 for all). The incidence of primary poor graft function (PGF) in the clinical cohort (n=55) was comparable to that in the matched-pair cohort (n=110) negative for the DSA (5% vs. 1%, P=0.076), both of which were significantly lower than that in the historical cohort (n=22) with 2,000 ≤ MFI<10,000 without receiving any treatment to cope with DSA (27%, P<0.001, for all). Rituximab desensitization was associated with a reduced incidence of primary PGF (HR 0.200, P=0.023). The 3-year non-relapse mortality of patients in the clinical cohort and the matched-pair cohort were 23% and 24%, respectively, both of which were lower than that of patients in the historical cohort (37%), although no statistical significance was observed. These results led to a low 3-year overall survival in patients in the historical cohort (58%) compared to those in the clinical cohort (71%) and the matched-pair cohort (73%). These results suggest that a single dose of rituximab could be effectively used to desensitize patients and prevent the onset of primary PGF in patients who receive HLA-mismatched allografts.

This study is registered at http://www.chictr.org.cn/ChiCTR-OPC-15006672.