Incidence and significance of Donor-Specific Antibodies in Haploidentical Stem Cell Transplantation: Single Centre Experience

Background: primary graft failure is a devastating complication after allogeneic transplant. Donor specific antibodies has been reported as a major risk factor contributing to graft failure. We retrospectively analyzed our haploidentical transplant registry to report the incidence and impact of DSA and anti-HLA on engraftment in a cohort of malignant hematologic disease conditioned with myeloablative regimens. Methods: retrospective analysis of consecutive cases with malignant hematologic disorders who received a myeloablative haplo-HSCT at a single center. Results: 107 patients were identified with a median recipient age of 22 and a median donor age of 31. Sixty-two patients had AML (58%), 29 had ALL (27%), and 16 (15%) had other malignancies. Sixty-one recipients (57%) had positive anti-HLA, 56 of them had the DSA results available, of these 17 patients had DSAs (15% of the total number of patients, or 28% of patients who have anti-HLA antibodies). The median cumulative MFI was 2062 (IQR: 1038 - 6500). Sixty three percent of the DSA were against class II HLA antigens, while 37% were against class I HLA antigens. The OS, CIR, aGvHD, and cGvHD did not differ between patients with and without anti-HLA antibodies, nor between patients with and without DSA. The gender of the recipient and donor, as well as the gender mismatch between recipient and donor, were statistically associated with the incidence of anti-HLA antibodies, but not with DSA. Three patients only developed GF (2.8%), one was primary (0.9%) and the other two had secondary GF (1.9%). None of the GF cases was in patients with anti-HLA antibodies or DSA. Conclusion: In our cohort, the presence of anti-HLA or DSAs did not affect the outcomes including the incidence of PGF following myeloablative haplo-HSCT for malignant hematologic disorders.