ALBERT

Description: While allogeneic donor hematopoietic cell transplantation (HCT) can cure non-Hodgkin lymphoma (NHL) by inducing a graft-versus-lymphoma effect, 10-35% of patients experience progression or relapse. We investigated whether the genotype of allogeneic donor natural killer (NK) cell killer immunoglobulin-like receptors (KIR) impacts the survival of lymphoma patients. The importance of KIR genetics in unrelated donor (URD) HCT has been demonstrated in AML where donors with favorable KIR gene content reduced the risk of relapse by 30%. Because the consequence of donor KIR genotype in NHL is unknown, we evaluated its effect on transplant outcome in 614 adults with NHL (28% follicular lymphoma, 16% diffuse large B cell lymphoma, 17% mantle cell lymphoma, 37% other) who underwent T cell replete URD HCT between 1990-2009 with outcomes reported to the Center for International Blood and Marrow Transplant Research (CIBMTR). Donor samples from the NMDP/CIBMTR Repository were genotyped (15 KIR genes) by MALDI-TOF mass spectroscopy. KIR haplotypes (A/A or B/x) were determined by presence/absence of individual KIR genes. Multivariate regression models were used to test the associations between donor KIR genotype and clinical outcome. The median patient age was 50 years (range 19-72), 93% were Caucasians and 62% had chemosensitive lymphoma. Most (60%) were 〉1.5 years from diagnosis; 41% received myeloablative preparative regimens and 61% received peripheral blood derived grafts. Most transplants were 10/10 matched for HLA alleles (n=396), the remainder 9/10 matched (n=158) or ≤8/10 matched (n=60). The frequencies of KIR genotypes in donors reflected the Caucasian population: 70% (n=428) were KIR B/x and 30% (n=180) were KIR A/A. Patients receiving 10/10 HLA-matched grafts (65%) experienced significantly lower relapse at 5 years when donors were KIR B/x genotype (n=281; 26% [95%CI 21-32%]) compared to KIR A/A genotype (n=115; 37% [95% CI 27-46%] ;p=0.05; Figure left) leading to improved progression-free survival (PFS) (35% [95% 26-44] vs. 22% [95%CI 11-35%]; p=0.02; Figure right). After adjusting for significant clinical variables, KIRB/x donors conferred significant protection against relapse (RR 0.63 [95%CI 0.43-0.92]; p=0.02) and improved PFS (RR 0.71 [95% CI 0.55-0.91]; p=0.008) compared to KIR A/A donors. The relapse protection and improved survival associated with KIR B/x donors was highly significant in the 10/10 HLA matched cohort (n=396) but not in the HLA-mismatched transplants (n=218; PFS RR 1.21 [95%CI 0.86-1.7]; Relapse RR 1.49 [0.87-2.55], p=NS for both). Importantly, the use of KIR B/x donors was associated with improved clinical outcomes for patients after both myeloablative and reduced intensity conditioning. Donor KIR genotype had no effect on rates of acute graft-versus-host disease (HR 1.05; p=0.86), and treatment related mortality at 1 year was similar for both groups (28% [B/x] and 30% [A/A]). In multivariate analysis of the entire cohort, other factors adversely impacting PFS included chemoresistant lymphoma (HR 1.52; p=0.03), disease other than follicular lymphoma (HR 1.34; p=0.0001) and

Description: There is now a bulk of evidence supporting a role for HLA-DPB1 matching status on the outcome in Haematopoietic Stem Cell Transplants (HSCT) from Unrelated Donors (UD). More recently analysis has focussed on matching status at particular epitopes or amino acid (aa) positions within the DPB1 molecule. Mismatches at this level may predict for transplant complications and this analysis may contribute towards better understanding of the function of DPB1. Within exon two of the DPB1 molecule (which forms the peptide binding groove, PBG) there are six Hypervariable Regions (HVR), A to F, which are present in patterns characteristic to antigen groups. Within each of these HVR there are one or more amino acids which are polymorphic and this polymorphism is important in determining the peptides which will bind, the recognition by T cell receptors or both. We analysed the outcome in 282 mixed transplant pairs who have received an HSCT from an unrelated donor. The majority of transplant protocols included T cell depletion (TCD) with CAMPATH (〉75%). All pairs had high resolution tissue typing for six HLA loci and, in order to remove confounding effects, were matched for HLA-A, -B, -C, -DRB1, -DQB1. Transplant pairs were assessed as matched or mismatched for HVRs A to F, as well as the individual amino acid positions in each of these regions, in a graft versus host direction. Mismatches at both amino acid position 57 (within HVR C) and 65 (within HVR D) were associated with transplant complications. Position 57 was matched in 233 pairs (83%) and mismatched in 49 (17%). A match at this position resulted in a significant survival advantage compared to those that were mismatched (3 years survival probability: 50% compared to 33%; log rank p=0.014). Position 65 was matched in 231 (82%) pairs and mismatched in 51 (18%). Matched pairs had a significantly improved overall survival (OS) compared to mismatched pairs (49% versus 35%; log rank p=0.039). The reason for the inferior OS was investigated. There was no significant association between matching at either position and graft versus host disease or disease relapse. In contrast, mismatched pairs had a significantly increased rate of transplant related mortality (TRM). The one year TRM was significantly increased in those pairs mismatched at positions 57 (19/42, 45% versus 52/192, 27%; log rank p=0.013) and 65 (19/45, 42% versus 52/189, 28%; log rank p=0.042). In order to rule out that the effects of mismatching for these positions were influenced by the number of allele incompatibilities present, the analysis was repeated only in those pairs with two DPB1 allele mismatches (n=82). The results mirrored those seen in the whole cohort. Although the crystal structure of DPB1 has yet to be solved, comparisons can be made with the structure and function of DRB1. Position 65 is analogous to position 67 in DRB1, and is known to be involved in peptide interactions in that molecule. Position 57 points away from the PBG, however may still interact with peptide as it is well recognised that Class II peptides “hang out” of the ends of the groove. In addition, these amino acids may determine recognition by T cells or other molecules. In conclusion, we have shown a significantly worse OS, largely mediated by an increased TRM, in recipients of HSCT from UD which are mismatched at aa positions 57 and 65 of the DPB1 molecule. We suggest this supports pre-transplant tissue typing for DPB1, both to aid in donor selection and in the prediction of outcome.

Description: Haematopoietic Stem Cell Transplantation (HSCT) using volunteer Unrelated Donors (UD) has become an important and viable option in the treatment of Acute Leukaemia (AL). While matching donors and recipients usually refers to five of the classical HLA genes (HLA-A, -B, -C, -DRB1 and -DQB1), the impact of a sixth gene, HLA-DPB1, on the outcome of UD-HSCT is increasingly emerging. We have previously shown an increased risk of relapse with HLA-DPB1 matching and independently, with NOD2/CARD15 genotype. In light of these data, we have analysed a larger UD-HSCT cohort in order to establish the impact on transplant outcome when both HLA-DPB1 matching status and NOD2/CARD15 genotype are considered. HLA typing and NOD2/CARD15 genotyping was performed on 304 AL patients and their Anthony Nolan Trust volunteer unrelated donors. Transplants occurred between 1996 and 2005 at UK transplant centres. Diagnoses were ALL (47%) and AML (53%). 67% of the cohort were a 10/10 HLA match with 16% also being matched for HLA-DPB1. Myeloablative conditioning regimens were used in 74% of transplants. T-cell depletion was included in 82% of conditioning protocols. Bone marrow was used in 72% of transplants with the remaining 28% using peripheral blood stem cells. Two forms of post-transplant immunosuppression predominated, Cyclosporine A and Methotrexate (47%) and Cyclosporine A alone (38%). Previous studies on a subgroup of this cohort showed that HLA-DPB1 matching and NOD2/CARD15 SNPs independently caused an increase in disease relapse. Consequently, the cohort was grouped into three categories to reflect this risk, group 1 (DPB1 matched; NOD2/CARD15 SNP, n=24), group 2 (HLA-DPB1 matched; NOD2/CARD15 Wild-Type (WT) or HLA-DPB1 mismatched; NOD2/CARD15 SNP, n=112) and group 3 (HLA-DPB1 mismatched; NOD2/CARD15 WT, n=168). There was a significant difference in disease relapse between the three groups (1 year: group 1; 68%, group 2; 48%, group 3; 30%, p=0.0038). This finding persisted in multivariate analysis where being in either group 2 or 3 was protective towards relapse as compared to group 1 (RR 0.321; 95% CI 0.167–0.616; p=0.001 and RR 0.478; 95% CI 0.244–0.934; p=0.031 respectively). In the group with the highest relapse risk (group 1), this resulted in a decrease in Overall Survival (OS) (33% vs 54% in group 3, RR 0.617; 95% CI 0.359–1.060; p=0.080). The best OS was seen in the group with the lowest risk of relapse (group 3). Here, in addition to low relapse, there was increased acute and chronic Graft-versus-Host Disease (GvHD) (p=0.0019 and p=0.0058 respectively). In this cohort, cGvHD (in its limited form) was associated with a significantly lower incidence of relapse (p=0.0066) and better OS (p

Description: A number of studies, considering diverse populations of recipients of Unrelated Donor (UD) Haematopoietic Stem Cell Transplants (HSCT), have shown an impact of the matching status of HLA-DPB1 on transplantation complications and/or outcome. Most of these studies have been performed in pairs who are completely matched for the other five important HLA loci, 10/10 (HLA-A, -B, -C, -DRB1, -DQB1). This excludes any additive or confounding effects due to other HLA mismatches. However, it is also known that while strong linkage disequilibrium exists between the other five HLA loci, this does not extend to DP. It may therefore be possible to analyse DPB1 matching as an individual risk factor (irrespective of the matching status for the other HLA molecules). We have analysed the outcome in 423 mixed transplant pairs who have received an HSCT from an unrelated donor. The majority of transplant protocols included T cell depletion (TCD) with CAMPATH (〉75%). All pairs had high resolution tissue typing performed for six HLA loci. Of the pairs, 282 were matched at 10/10 alleles and 141 had mismatches for one or more of 10/10 alleles. There was no association between matching for DPB1 and matching for the other HLA types. In the 282 HLA matched pairs, 29% were DPB1 matched, and in the 141 HLA mismatched pairs, 28% were matched for DPB1. We first analysed the impact of DPB1 matching in only those pairs who were matched for five HLA loci (N=282). The three year probability of relapse was 61% (median: 461 days). There was a highly significantly increase in disease relapse in DPB1 matched pairs (74%) as compared to those pairs with either one or two DPB1 mismatches (56%) (log rank, p=0.001). There was no difference in this effect as the number of DPB1 incompatibilities increased (i.e. one or two incompatibilities were equally protective, 56% versus 55% respectively, log rank p=0.959). This finding persisted in a multivariate analysis including factors known to be associated with disease relapse. We next analysed the impact of DPB1 matching on disease relapse in the group overall (N=423). There was a significantly increased risk of relapse in this cohort if DPB1 was matched (log rank; p=0.0001). This finding persisted when only the pairs with one or more mismatches for 10/10 alleles were considered (N=141) (log rank; p=0.031). When the cohort was divided according to disease subgroup, we found similar results in both CML and ALL - the risk of disease relapse when DPB1 is matched was significantly higher than when it was mismatched (log rank; p=0.0009 and p=0.013 respectively). Although there was no significant difference in the overall survival dependant on DPB1 matching in the group overall, in ALL DPB1 matched pairs had a significantly worse overall survival (log rank; p=0.025). Thus, in recipients of TCD UD HSCT, a match for DPB1 is associated with a significantly increased risk of disease relapse, irrespective of the matching status for the other HLA molecules. No other HLA locus had any impact on disease relapse. We speculate that this may indicate that DPB1 plays a different role within the immune system to the other HLA molecules. It is possible that DPB1 interacts with molecules besides T cells (such as NK cells) for which it may serve as a ligand. These effects may be more marked following transplants using CAMPATH, as many cell types are depleted, and thus the ratio of recovering cells is skewed in comparison to the situation which exists after a T cell replete transplant.