CT-026 Prevalence and Impact of Donor Specific Anti-HLA Antibodies in the Setting of Myeloablative Haploidentical Transplant for Malignant Hematological Diseases: Single-Center Experience

Abstract

To study the outcomes, prevalence, and impact of DSA and anti-HLA of myeloablative haploidentical transplant for malignant hematological diseases. We conducted retrospective analysis of our blood and marrow transplant database. We identified 107 patients who received myeloablative haploidentical hematopoietic cell transplantation between January 2013 and December 2020. Sixty-two recipients were male (58%) and 45 were female (48%). The median recipient age was 22 (range: 1-56). Most pairs had matched ABO blood groups (76 pairs [71%]). The graft source was bone marrow in 83 patients (78%). The median infused CD34 cell dose was 4.02×106/kg (range: 1.3-13.1). Sixty-one recipients (57%) had positive anti-HLA; of these, 17 had DSA (15% of the total number of patients, 28% of patients with anti-HLA antibodies). The median cumulative mean fluorescence intensity was 2,062 (IQR: 1,038-6,500). Overall survival, cumulative incidence of relapse, acute graft-versus-host disease, and chronic graft-versus-host disease were comparable between patients with anti-HLA antibodies and those without and between patients with DSA and those without. Recipient and donor gender and recipient/donor gender mismatch showed statistical association with the incidence of anti-HLA antibodies but not DSA. Of the 17 patients with DSA, five underwent desensitization. C1q assay was done pre and post desensitization. Three patients developed GF (2.8%): one was primary (0.9%) due to low CD34 dose, and two had secondary GF (1.9%). None of these cases occurred in patients with anti-HLA antibodies or DSA. The median time from transplant to GF was 2.23 months (range: 0.8-2.89). The median time to absolute neutrophil count and platelet engraftment was 16 days. Our study shows that desensitization may not be required in the setting of myeloablative transplant for malignant hematological disorders. This warrants further investigations in prospective trials.