Analysis of Single Nucleotide Polymorphisms in the Gamma Block of the Major Histocompatibility Complex in Association with Clinical Outcomes of Hematopoietic Cell Transplantation: A Center for International Blood and Marrow Transplant Research Study

HLA haplotype mismatches have been associated with an elevated risk of acute graft-versus-host disease (aGVHD) in patients undergoing HLA-matched unrelated donor (URD) hematopoietic cell transplantation (HCT). The gamma block (GB) is located in the central MHC region between beta and delta blocks (encoding HLA-B and -C and HLA-DQ and -DR antigens, respectively) and contains numerous inflammatory and immune regulatory genes, including Bf, C2, and C4 genes. A single-center study showed that mismatches in SNPs c.2918+98G, c.3316C, and c.4385C in the GB block (C4 SNPs) were associated with higher risk of grade III-IV aGVHD. We investigated the association of GB SNP (GBS) mismatches with outcomes after 10/10 and 9/10 URD HCT (n?=?714). The primary outcome was acute GVHD. Overall survival, disease-free survival, transplantation-related mortality, relapse, chronic GVHD, and engraftment were also analyzed. DNA samples were GBS genotyped by identifying 338 SNPs across 20 kb using the Illumina NGS platform. The overall 100-day incidence of aGVHD grade II-IV and II-IV were 41% and 17%, respectively. The overall incidence of matching at all GBSs tested and at the C4 SNPs were 23% and 81%, respectively. Neither being matched across all GB SNPs tested (versus mismatched) nor having a higher number of GBS mismatches was associated with transplantation outcomes. There was no association between C4 SNP mismatches and outcomes except for an unexpected significant association between having 2 C4 SNP mismatches and a higher hazard ratio (HR) for relapse (association seen in 15 patients only; HR, 3.38, 95% confidence interval, 1.75 to 6.53; P?=?.0003). These data do not support the hypothesis that mismatching at GB is associated with outcomes after HCT.     

Collection,Cryostorage, Transplantation,and Disposal of Hematopoietic Stem Cell Products

Many transplantation centers routinely collect 1 or more autologous peripheral blood stem cell (PBSC) grafts in patients with hemato-oncologic and autoimmune disorders. However, subsequent high-dose chemotherapy and autologous blood stem cell transplantation (ABSCT) are often not performed, for various reasons. Currently, little is known about the actual utilization rate of stored PBSCs. We retrospectively analyzed the collection, storage, and disposal practices of PBSC products from a large cohort of patients (n?=?1020) with hematologic, oncologic, and autoimmune disorders at our institution over a 12-year period. Patients with multiple myeloma were excluded. Based on our institution-specific charges, we estimated the costs for PBSC collection/processing and storage. The median number of sufficient PBSC collections per patient in the whole cohort was 2 (range, 1 to 6). We could demonstrate that only 67% of all patients who had collected sufficient PBSCs for transplantation actually underwent ABSCT, and only a small minority of all patients (4%) underwent multiple ABSCTs. The actual use of the stored PBSC grafts varied among disease entities from >80% to 0%. From a retrospective standpoint, the collected and discarded (definitively not used) or stored (potentially not used) cryostored PBSCs were associated with considerable costs of collection, cryopreservation, and long-term cryostorage. Although keeping open the therapeutic option for future transplantations may be important, there is currently a huge discrepancy between collection/storage practices and actual utilization of the cryopreserved PBSCs, at a considerable cost and strain on patients. Our study provides a rationale for reevaluating the present standards.