Long-term follow-up after R-High CHOP/CHASER/LEED with Auto-PBSCT in untreated mantle cell lymphoma-Final analysis of JCOG0406.

Progression-free survival after R-High CHOP/CHASER/LEED with auto-PBSCT in untreated mantle cell lymphoma in JCOG0406 study. A continuous pattern of relapse was observed.

HLA-B leader and survivorship after HLA-mismatched unrelated donor transplantation.

Hematopoietic cell transplantation (HCT) from HLA-mismatched unrelated donors can cure life-threatening blood disorders, but its success is limited by graft-versus-host disease (GVHD). HLA-B leaders encode methionine (M) or threonine (T) at position 2 and give rise to TT, MT, or MM genotypes. The dimorphic HLA-B leader informs GVHD risk in HLA-B-mismatched HCT. If the leader influences outcome in other HLA-mismatched transplant settings, the success of HCT could be improved for future patients. We determined leader genotypes for 10 415 patients receiving a transplant between 1988 and 2016 from unrelated donors with one HLA-A, HLA-B, HLA-C, HLA-DRB1, or HLA-DQB1 mismatch. Multivariate regression methods were used to evaluate risks associated with patient leader genotype according to the mismatched HLA locus and with HLA-A, HLA-B, HLA-C, HLA-DRB1, or HLA-DQB1 mismatching according to patient leader genotype. The impact of the patient leader genotype on acute GVHD and mortality varied across different mismatched HLA loci. Nonrelapse mortality was higher among HLA-DQB1-mismatched MM patients compared with HLA-DQB1-mismatched TT patients (hazard ratio, 1.35; P = .01). Grades III to IV GVHD risk was higher among HLA-DRB1-mismatched MM or MT patients compared with HLA-DRB1-mismatched TT patients (odds ratio, 2.52 and 1.51, respectively). Patients tolerated a single HLA-DQB1 mismatch better than mismatches at other loci. Outcome after HLA-mismatched transplantation depends on the HLA-B leader dimorphism and the mismatched HLA locus. The patient's leader variant provides new information on the limits of HLA mismatching. The success of HLA-mismatched unrelated transplantation might be enhanced through the judicious selection of mismatched donors for a patient's leader genotype.

Donor UNC-93 Homolog B1 genetic polymorphism predicts survival outcomes after unrelated bone marrow transplantation.

UNC-93 homolog B1 (UNC93B1) is a key regulator of toll-like receptors (TLRs), pattern recognition receptors that sense invading pathogens and manage the innate immune response and deliver them from the endoplasmic reticulum to their respective endosomal signaling compartments. Several types of TLRs are known to contribute to the inflammatory process after allogeneic hematopoietic stem cell transplantation (SCT), so UNC93B1 might play integral roles there. We investigated the influence of the UNC93B1 single-nucleotide polymorphism (SNP) rs308328 (T>C) on transplant outcomes in a cohort of 237 patients undergoing unrelated HLA-matched bone marrow transplantation (BMT) for hematologic malignancies through the Japan Marrow Donor Program. The donor UNC93B1 C/C genotype was associated with a better 3-year overall survival than the donor UNC93B1 C/T or T/T genotype. An analysis of the UNC93B1 rs308328 genotype may therefore be useful for selecting the donor, estimating the prognosis, and creating therapeutic strategies after allogeneic SCT.

R-CHOP-14 versus R-CHOP-14/CHASER for upfront autologous transplantation in diffuse large B-cell lymphoma: JCOG0908 study.

The efficiency of upfront consolidation with high-dose chemotherapy/autologous stem-cell transplantation (HDCT/ASCT) for newly diagnosed high-risk diffuse large B-cell lymphoma (DLBCL) may be influenced by induction chemotherapy. To select better induction chemotherapy regimens for HDCT/ASCT, a randomized phase II study was conducted in high-risk DLBCL patients having an age-adjusted International Prognostic Index (aaIPI) score of 2 or 3. As induction chemotherapy, 6 cycles of R-CHOP-14 (arm A) or 3 cycles of R-CHOP-14 followed by 3 cycles of CHASER (arm B) were planned, and patients who responded proceeded to HDCT with LEED and ASCT. The primary endpoint was 2-y progression-free survival (PFS), and the main secondary endpoints included overall survival, overall response rate, and adverse events (AEs). In total, 71 patients were enrolled. With a median follow-up of 40.3 mo, 2-y PFS in arms A and B were 68.6% (95% confidence interval [CI], 50.5%-81.2%) and 66.7% (95% CI: 48.8%-79.5%), respectively. Overall survival at 2 y in arms A and B was 74.3% (95% CI: 56.4%-85.7%) and 83.3% (95% CI: 66.6%-92.1%). Overall response rates were 82.9% in arm A and 69.4% in arm B. During induction chemotherapy, 45.7% and 75.0% of patients in arms A and B, respectively, had grade ≥ 3 non-hematologic toxicities. One patient in arm A and 6 in arm B discontinued induction chemotherapy due to AEs. In conclusion, R-CHOP-14 showed higher 2-y PFS and less toxicity compared with R-CHOP-14/CHASER in patients with high-risk DLBCL, suggesting the former to be a more promising induction regimen for further investigations (UMIN-CTR, UMIN000003823).

Effects of Haplotype Matching on Outcomes after Adult Single-Cord Blood Transplantation.

It remains unclear whether the HLA haplotype of unrelated cord blood (UCB) should be matched to that of the patient in single UCB transplantation. Thus, using data from a Japanese registry, we analyzed the effect of haplotype matching on outcomes. Patients with hematologic diseases aged 16 years or older who had undergone their first transplant were included (N = 1347). The effects of haplotype matching and high-frequency HLA haplotype on outcomes were analyzed. Median patient age was 55 years. The cumulative incidences of neutrophil engraftment among groups with 0, 1, and 2 HLA haplotype matches were 79%, 82%, and 88%, respectively (P = .008). In a multivariate analysis, the group with 0 haplotype matches was marginally associated with worse neutrophil engraftment (P = .087) and significantly associated with platelet engraftment (P = .044) compared with the group with 1 haplotype match. Two-haplotype matches were associated with a higher risk of relapse. In the group with 1 haplotype match, the top 3 shared haplotypes were "A*24:02-B*52:01-C*12:02-DRB1*15:02" (HP-P1), "A*33:03-B*44:03-C*14:03-DRB1*13:02" (HP-P2), and "A*24:02-B*07:02-C*07:02-DRB1*01:01" (HP-P3). The presence of HP-P2 but not HP-P1 or HP-P3 was associated with a decreased risk of grades II to IV acute graft-versus-host disease (hazard ratio, .56; P = .001) but an increased risk of relapse (hazard ratio, 1.35; P = .045). HLA haplotype matching might be considered to improve engraftment. Two-haplotype matches should be avoided if the relapse risk is high. The haplotype itself may have an effect on the risk of acute graft-versus-host disease and relapse.

Impact of HLA Allele Mismatch at HLA-A, -B, -C, and -DRB1 in Single Cord Blood Transplantation.

The impact of allele-level HLA mismatch on outcomes of cord blood transplantation has not been well established. We retrospectively analyzed the effects of HLA allele matching at HLA-A, -B, -C, and -DRB1 in cord blood transplantation for acute myeloid leukemia, acute lymphoblastic leukemia, and myelodysplastic syndrome. In multivariate analysis, overall survival (OS) significantly deteriorated in the 4-allele or higher mismatch in pediatric cases (hazard ratio, 1.8 for 4/8 match [reference, 6/8 match] and 2.85 for 3-1/8 match) and the 5-allele or higher mismatch in adult cases (hazard ratio, 1.23 for 3-0/8 match). Incidence of grade Ⅲ to Ⅳ acute graft-versus-host disease was low in the 8/8 match and 1-allele mismatch in pediatric cases (hazard ratio, 0.19 for 8/8 match and 0.41 for 7/8 match) and the 8/8 match in adult cases (hazard ratio, 0.41 for 8/8 match). On the other hand, a higher incidence of relapse was noted in the 8/8 match in adults (hazard ratio, 1.53). The incidence of neutrophil and platelet engraftment decreased in the 3-allele or higher mismatch in adults. In subgroup analysis of graft-versus-host disease prophylaxis in adult cases, a deteriorating effect on OS of HLA 5-allele or higher mismatch was more significant in cases with calcineurin inhibitor with methotrexate than with mycophenolate mofetil. These results suggest that allele-level HLA mismatch affects the outcomes of cord blood transplantation. Information on HLA allele matching at HLA-A, -B, -C, and -DRB1 may be useful for cord blood unit selection.

Increased Relapse Risk of Acute Lymphoid Leukemia in Homozygous HLA-C1 Patients after HLA-Matched Allogeneic Transplantation: A Japanese National Registry Study.

Natural killer (NK) cells expressing killer cell immunoglobulin-like receptors (KIRs) can recognize specific HLA class I molecules as their ligands. By studying a large Japanese transplant registry, we compared transplant outcomes between patients heterozygous for HLA-CAsn80/CLys80 (HLA-C1/C2) and those homozygous for HLA-C1 (HLA-C1/C1) among patients who had undergone HLA-matched hematopoietic stem cell transplantation (HSCT). A high frequency of KIR2DL1 with strong HLA-C2 binding capacity and a low frequency of HLA-C2 and KIR haplotype B are characteristic of the Japanese population. In our previous report, HLA-C1/C1 patients with myeloid leukemia were less likely to relapse than HLA-C1/C2 patients. We newly assessed 2884 patients with acute lymphoblastic leukemia (ALL) who received HLA-matched allogeneic HSCT and analyzed their leukemia relapses by using adjusted competing-risk methods. HLA-C1/C1 patients with ALL experienced significantly higher relapse rates than HLA-C1/C2 patients (hazard ratio [HR] = 1.55, P = .003), contrary to our results in patients with myeloid leukemia. We allocated patients with ALL to several subgroups and found a higher frequency of relapse (HR >1.8) in the HLA-C1/C1 group than in the HLA-C1/C2 group among patients with Ph-negative ALL, those who had no cytomegalovirus reactivation, those who received transplants from donors who were aged 41 years or older, and those who experienced acute graft-versus-host disease, especially if it required systemic treatment. One interpretation of our results is that KIR2DL1-positive NK cells disrupt T cells, antigen-presenting cells, or both from working efficiently in transplant immunity in HLA-C1/C1 patients with ALL. Another is that KIR2DS1-positive NK cells directly attack HLA-C2-positive ALL blasts in HLA-C1/C2 patients. Whether HLA-C2 can cause recurrence to decrease or increase in patients depending on the disease (ALL or myeloid leukemia) will be a very important finding. We hope that our results will provide clues to the real mechanisms behind relapse after transplantation in patients with different HLA profiles.

Impact of Homozygous Conserved Extended HLA Haplotype on Single Cord Blood Transplantation: Lessons for Induced Pluripotent Stem Cell Banking and Transplantation in Allogeneic Settings.

Induced pluripotent stem cells (iPSCs) have been applied to clinical regenerative cell therapy. Recently, an iPSC banking system to collect HLA haplotype (HP) homozygous (homo) cells for iPSC transplantation in allogeneic settings was proposed, and tissue transplantation generated from iPSC through banking has just began. We analyzed 5017 single cord blood transplantation (CBT) pairs with HLA-A, -B, -C, -DRB1 allele typing data and found 39 donor HLA homo donor to patient HLA heterozygous (hetero) pairs. Of note, all 39 HLA homo to hetero pairs engrafted neutrophils, except 1 early death pair, and all 30 assessable pairs engrafted platelets. Acute graft-versus-host disease (GVHD) grades II to IV and grades III to IV occurred in 17 and 3 of 38 assessable pairs, respectively. Competing risk regression analysis revealed a favorable risk of neutrophil engraftment and higher risk of acute GVHD compared with HLA-matched CBTs. Thirty-seven of 39 homo to hetero pairs had conserved extended HLA HPs (HP-1, n = 18; HP-2, n = 8; HP-3, n = 7; HP-4, n = 4; HP-5, n = 1) that were ethnicity-specific, and at least 1 of 2 patient HLA-A, -B, -C, and -DRB1 alleles in each locus were invariably shared with the same donor HP in 35 pairs. These findings confirmed our preliminary results with 6 HLA homo CBTs, and a trend of high incidence of acute GVHD was newly observed. Importantly, they imply the possibility that HLA-homo iPSC transplantation provides favorable engraftment and accordingly imply the merit of banking iPSC with homozygous major conserved extended HLA HPs.

Evolutionary basis of HLA-DPB1 alleles affects acute GVHD in unrelated donor stem cell transplantation.

HLA-DPB1 T-cell epitope (TCE) mismatching algorithm and rs9277534 SNP at the 3' untranslated region (3'UTR) in the HLA-DPB1 gene are key factors for transplant-related events in unrelated hematopoietic cell transplantation (UR-HCT). However, the association of these 2 mechanisms has not been elucidated. We analyzed 19 frequent HLA-DPB1 alleles derived from Japanese healthy subjects by next-generation sequencing of the entire HLA-DPB1 gene region and multi-SNP data of the HLA region in 1589 UR-HCT pairs. The risk of acute graft-versus-host disease (aGVHD) was analyzed in 1286 patients with single HLA-DPB1 mismatch UR-HCT. The phylogenetic tree constructed using the entire gene region demonstrated that HLA-DPB1 alleles were divided into 2 groups, HLA-DP2 and HLA-DP5. Although a phylogenetic relationship in the genomic region from exon 3 to 3'UTR (Ex3-3'UTR) obviously supported the division of HLA-DP2 and HLA-DP5 groups, which in exon 2 showed intermingling of HLA-DPB1 alleles in a non-HLA-DP2 and non-HLA-DP5-group manner. Multi-SNP data also showed 2 discriminative HLA-DPB1 groups according to Ex3-3'UTR. Risk of grade 2-4 aGVHD was significantly higher in patient HLA-DP5 group mismatch than patient HLA-DP2 group mismatch (hazard ratio, 1.28; P = .005), regardless of donor mismatch HLA-DP group. Regarding TCE mismatch, increasing risk of aGVHD in patient HLA-DP5 group mismatch and TCE-nonpermissive mismatch were observed only in patients with TCE-permissive mismatch and patient HLA-DP2 group mismatch, respectively. Evolutionary analysis revealed that rs9277534 represented a highly conserved HLA-DPB1 Ex3-3'UTR region and may provoke aGVHD differently to TCE mismatching algorithm, reflecting exon 2 polymorphisms. These findings enrich our understanding of the mechanism of aGVHD in HLA-DPB1 mismatch UR-HCT.

Comparison of HLA Allele Mismatch and Antigen Mismatch in Unrelated Bone Marrow Transplantation in Patients with Leukemia.

We compared the effect of HLA single-antigen and single-allele mismatched unrelated bone marrow transplantation (UBMT) without in vivo/ex vivo T cell depletion. Becasue a single DRB1 mismatch is preferred among 1-allele or 1-antigen mismatched donors, we performed mismatched allele- or antigen-specific analyses with a single DRB1 mismatch as the reference. In adjusted comparison by multivariate analyses, an HLA-DRB1 single-allele mismatch resulted in a decreased risk of nonrelapse mortality (NRM; relative risk [RR], 1.33; 95% confidence interval [CI], 1.08 to 1.63, P = .006) compared with an HLA-DR single-antigen mismatch and conferred a decreased risk of NRM (RR, 1.25; 95% CI, 1.01 to 1.57; P = .025) and overall mortality (RR, 1.16; 95% CI, 1.00 to 1.37; P = .046) compared with an HLA-C single-antigen mismatch. Relative to an HLA-DRB1 single-allele mismatch, 2-mismatch transplants, including those with 1 or more antigen mismatches, resulted in a significantly increased risk of NRM (1-antigen/1-allele mismatch: RR, 1.68; 95% CI, 1.03 to 2.05; P < .001; 2-antigen mismatch: RR, 1.58; 95% CI, 1.04 to 2.02; P = .001) and overall mortality (1-antigen/1-allele mismatch: RR, 1.27; 95% CI, 1.09 to 1.47; P = .002; 2-antigen mismatch: RR, 1.27; 95% CI, 1.03 to 1.57; P = .02). NRM correlated with the combined number of mismatches and allele or antigen mismatches, with rates of 22%, 27%, 32%, 31%, and 38% at 4years for full match, single-allele mismatch, single-antigen mismatch, 2-allele mismatch, and 2 mismatches that included an antigen mismatch, respectively. Our results support the preference for an allele mismatch rather than an antigen mismatch in unrelated bone marrow donors with 1 DR mismatch or 2 mismatches for T cell-replete UBMT.

Recipient ADAMTS13 Single-Nucleotide Polymorphism Predicts Relapse after Unrelated Bone Marrow Transplantation for Hematologic Malignancy.

Relapse remains a major obstacle to the survival of patients with hematologic malignancies after allogeneic hematopoietic stem cell transplantation. A disintegrin-like and metalloprotease with a thrombospondin type 1 motif (ADMATS13), which cleaves von Willebrand factor multimers into less active fragments, is encoded by the ADAMTS13 gene and has a functional single-nucleotide polymorphism (SNP) rs2285489 (C > T). We retrospectively examined whether ADAMTS13 rs2285489 affected the transplant outcomes in a cohort of 281 patients who underwent unrelated human leukocyte antigen (HLA)-matched bone marrow transplantation for hematologic malignancies. The recipient ADAMTS13 C/C genotype, which putatively has low inducibility, was associated with an increased relapse rate (hazard ratio [HR], 3.12; 95% confidence interval [CI], 1.25⁻7.77; P = 0.015), resulting in a lower disease-free survival rate in the patients with a recipient C/C genotype (HR, 1.64; 95% CI, 1.01⁻2.67; P = 0.045). Therefore, ADAMTS13 rs2285489 genotyping in transplant recipients may be a useful tool for evaluating pretransplantation risks.

R-High-CHOP/CHASER/LEED with autologous stem cell transplantation in newly diagnosed mantle cell lymphoma: JCOG0406 STUDY.

Although induction immunochemotherapy including high-dose cytarabine and rituximab followed by high-dose chemotherapy (HDC) with autologous stem cell transplantation (ASCT) is recommended for younger patients (≤65 years old) with untreated mantle cell lymphoma (MCL), no standard induction and HDC regimen has been established. We conducted a phase II study of induction immunochemotherapy of R-High-CHOP/CHASER followed by HDC of LEED with ASCT in younger patients with untreated advanced MCL. Eligibility criteria included untreated MCL, stage II bulky to IV, and age 20-65 years. Patients received 1 cycle of R-High-CHOP followed by 3 cycles of CHASER every 3 weeks. Peripheral blood stem cells (PBSC) were harvested during CHASER. LEED with ASCT was delivered to patients who responded to R-High-CHOP/CHASER. Primary endpoint was 2-year progression-free survival (PFS). From June 2008 to June 2012, 45 patients (median age 59 years; range 38-65 years) were enrolled. PBSC were successfully harvested from 36 of 43 patients. Thirty-five patients completed ASCT. Two-year PFS was 77% (80% CI 68-84), which met the primary endpoint. Five-year PFS and overall survival were 52% (95% CI 34-68%) and 71% (95% CI 51-84%), respectively. Overall response and complete response rates after induction immunochemotherapy were 96% and 82%, respectively. The most common grade 4 toxicities were hematological. In younger patients with untreated MCL, R-High-CHOP/CHASER/LEED with ASCT showed high efficacy and acceptable toxicity, and it can now be considered a standard treatment option.

Homozygous HLA-C1 is Associated with Reduced Risk of Relapse after HLA-Matched Transplantation in Patients with Myeloid Leukemia.

Natural killer (NK) cells assume graft-versus-leukemia alloreactivity after hematopoietic stem cell transplantation (HSCT) through their inhibitory killer cell immunoglobulin-like receptors (KIRs). KIR2D family members recognize HLA-C alleles with Asn80 (HLA-C1) or Lys80 (HLA-C2). The predominance of HLA-C1 over HLA-C2 and the frequent presence of KIR2DL1 are characteristic of Japanese people. We compared clinical outcomes among homozygous HLA-C1 (HLA-C1/C1) patients and heterozygous HLA-C1/C2 patients who underwent HLA-matched HSCT for hematologic malignancies by assessing the data of 10,638 patients from the Japanese national registry. HLA-C1/C1 recipients had a lower rate of relapse than HLA-C1/C2 recipients after transplantation for acute myelogenous leukemia (AML) (hazard ratio [HR], .79; P = .006) and chronic myelogenous leukemia (CML) (HR, .48; P = .025), but not for acute lymphoblastic leukemia (HR, 1.36), lymphoma (HR, .97), or low-grade myelodysplastic syndrome (HR, 1.40). We then grouped AML and CML patients together and divided them into several subgroups. Advantages of HLA-C1/C1 recipients over HLA-C1/C2 recipients regarding relapse were observed irrespective of donor relation (related: HR, .79, P = .069; unrelated: HR, .77, P = .022), preparative regimen (myeloablative: HR, .79, P = .014; reduced intensity: HR, .73, P = .084), and occurrence of acute graft-versus-host disease (yes: HR, .70, P = .122; no, HR .71, P = .026) or cytomegalovirus reactivation (reactivated: HR .67,P = .054; nonreactivated: HR .71, P = .033); however, these advantages were not observed in recipients with a delay in achieving complete chimerism (HR, 1.06). The advantage of decreasing relapse and extending relapse-free survival of C1/1 over C1/2 KIR-ligand status was most pronounced in T cell-depleted HSCT (HR, .27; P < .001 and HR, .30; P = .002, respectively) and in children age <15 years (HR, .29; P < .001 and HR .31; P < .001, respectively). Our findings represent an important mechanism responsible for the immunity against HLA-C2-negative myeloid leukemia cells after HLA-matched transplantation.

Role of Genetic Polymorphism of ALDH2 in Hematopoietic Stem Cell Transplantation.

Aldehyde dehydrogenase 2 (ALDH2) is involved in critically important biological processes, such as the metabolism of aldehydes and aldehyde-induced genotoxicity in hematopoietic stem cells. Given its role in these biological processes, we hypothesized that a functional ALDH2 polymorphism could affect transplantation outcomes after hematopoietic stem cell transplantation. Here, we analyzed the Japanese national registry data for 409 patients who underwent allogeneic bone marrow transplantation (BMT) from HLA-matched unrelated donors. To evaluate the impact of the recipient and donor ALDH2 polymorphism on transplantation outcomes, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for potential confounders. The recipient ALDH2 Lys/Lys genotype was significantly associated with higher transplantation-related mortality (TRM), with an HR relative to Glu/Glu genotype of 2.45 (95% CI, 1.22 to 4.90). The recipient Lys/Lys genotype also tended to be associated with delayed platelet engraftment (HR, .66; 95% CI, .43 to 1.03). In conclusion, we observed increased TRM among recipients with the ALDH2 Lys/Lys genotype in HLA fully matched BMT. We also observed a suggestive association with delayed platelet engraftment, which warrants further examination. These results may suggest that the recipient ALDH2 genotype affects the metabolism of endogenous aldehydes, leading to a significant impact on transplantation outcomes.

Genome-wide surveillance of mismatched alleles for graft-versus-host disease in stem cell transplantation.

Acute graft-versus-host disease (aGVHD) represents one of the major complications in allogeneic stem cell transplantation and is primarily caused by genetic disparity between the donor and recipient. In HLA-matched transplants, the disparity is thought to be determined by loci encoding minor histocompatibility antigens (minor H antigens), which are presented by specific HLA molecules. We performed a genome-wide association study (GWAS) to identify minor H antigen loci associated with aGVHD. A total of 500 568 single nucleotide polymorphisms (SNPs) were genotyped for donors and recipients from 1589 unrelated bone marrow transplants matched for HLA-A, -B, -C, -DRB1, and -DQB1, followed by the imputation of unobserved SNPs. We interrogated SNPs whose disparity between the donor and recipient was significantly associated with aGVHD development. Without assuming HLA unrestriction, we successfully captured a known association between HLA-DPB1 disparity (P = 4.50 × 10(-9)) and grade II-IV aGVHD development, providing proof of concept for the GWAS design aimed at discovering genetic disparity associated with aGVHD. In HLA-restricted analyses, whereby association tests were confined to major subgroups sharing common HLA alleles to identify putative minor H antigen loci, we identified 3 novel loci significantly associated with grade III-IV aGVHD. Among these, rs17473423 (P = 1.20 × 10(-11)) at 12p12.1 within the KRAS locus showed the most significant association in the subgroup, sharing HLA-DQB1*06:01. Our result suggested that a GWAS can be successfully applied to identify allele mismatch associated with aGVHD development, contributing to the understanding of the genetic basis of aGVHD.

Biological significance of HLA locus matching in unrelated donor bone marrow transplantation.

We hypothesized that the compatibility of each HLA loci between donor and patient induced divergent transplant-related immunologic responses, which attributed to the individualized manifestation of clinical outcomes. Here, we analyzed 7898 Japanese pairs transplanted with T-cell-replete marrow from an unrelated donor with complete HLA allele typing data. Multivariable competing risk regression analyses were conducted to evaluate the relative risk (RR) of clinical outcomes after transplantation. A significant RR of HLA allele mismatch compared with match was seen with HLA-A, -B, -C, and -DPB1 for grade III-IV acute graft-versus-host disease (GVHD), and HLA-C for chronic GVHD. Of note, only HLA-C and HLA-DPB1 mismatch reduced leukemia relapse, and this graft-versus-leukemia effect of HLA-DPB1 was independent of chronic GVHD. HLA-DRB1 and HLA-DQB1 double (DRB1_DQB1) mismatch was revealed to be a significant RR for acute GVHD and mortality, whereas single mismatch was not. Thus, the number of HLA-A, -B, -C, -DPB1, and DRB1_DQB1 mismatches showed a clear-cut risk difference for acute GVHD, whereas the number of mismatches for HLA-A, -B, -C, and DRB1_DQB1 showed the same for mortality. In conclusion, we determined the biological response to HLA locus mismatch in transplant-related immunologic events, and provide a rationale for use of a personalized algorithm for unrelated donor selection.

Comparison of Outcomes of 8/8 and 7/8 Allele-Matched Unrelated Bone Marrow Transplantation and Single-Unit Cord Blood Transplantation in Adults with Acute Leukemia.

To investigate an up-to-date alternative donor selection strategy, we compared the transplantation outcomes of 8/8 and 7/8 allele-matched unrelated bone marrow transplantation (UBMT) with those of umbilical cord blood transplantation (UCBT) and redefined the role of UCBT with extended analysis. Using Cox and competing risk regression analyses, we analyzed the transplantation outcomes in adult patients with acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). A total of 2472 first myeloablative transplantations between 2000 and 2010 were included (8/8 UBMT, 1001; 7/8 UBMT, 656; UCBT, 815). For acute and chronic graft-versus-host disease (GVHD) and nonrelapse mortality (NRM), we applied the combined analyses including both AML and ALL data. In the multivariate analyses, severe acute GVHD and NRM after UCBT were comparable with 8/8 UBMT, whereas those after 7/8 UBMT were significantly higher. The incidence of extensive chronic GVHD was significantly lower with UCBT compared with after 8/8 and 7/8 UBMT. With adjusted analyses for AML, UCBT and 8/8 UBMT showed similar overall survival (OS), whereas 7/8 UBMT showed inferior OS. For ALL, we found no significant difference in OS among the 3 groups. Cord blood may be the first choice alternative to 8/8 UBMT for both AML and ALL.

Late Mortality and Causes of Death among Long-Term Survivors after Allogeneic Stem Cell Transplantation.

We sought to assess the late mortality risks and causes of death among long-term survivors of allogeneic hematopoietic stem cell transplantation (HCT). The cases of 11,047 relapse-free survivors of a first HCT at least 2 years after HCT were analyzed. Standardized mortality ratios (SMR) were calculated and specific causes of death were compared with those of the Japanese population. Among relapse-free survivors at 2 years, overall survival percentages at 10 and 15 years were 87% and 83%, respectively. The overall risk of mortality was significantly higher compared with that of the general population. The risk of mortality was significantly higher from infection (SMR = 57.0), new hematologic malignancies (SMR = 2.2), other new malignancies (SMR = 3.0), respiratory causes (SMR = 109.3), gastrointestinal causes (SMR = 3.8), liver dysfunction (SMR = 6.1), genitourinary dysfunction (SMR = 17.6), and external or accidental causes (SMR = 2.3). The overall annual mortality rate showed a steep decrease from 2 to 5 years after HCT; however, the decrease rate slowed after 10 years but was still higher than that of the general population at 20 years after HCT. SMRs in the earlier period of 2 to 4 years after HCT and 5 years or longer after HCT were 16.1 and 7.4, respectively. Long-term survivors after allogeneic HCT are at higher risk of mortality from various causes other than the underlying disease that led to HCT. Screening and preventive measures should be given a central role in reducing the morbidity and mortality of HCT recipients on long-term follow-up.

Influence of Differently Licensed KIR2DL1-Positive Natural Killer Cells in Transplant Recipients with Acute Leukemia: A Japanese National Registry Study.

Licensing by self MHC class I ligands is required for proper natural killer (NK) cell response. NK cells with inhibitory killer cell immunoglobulin-like receptors for nonself MHC exhibit transient alloreactivity after hematopoietic stem cell transplantation (HSCT). We analyzed 3866 recipients in the Japan national registry who underwent their first allogeneic HSCT for acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) from HLA-A, -B, and -DRB1 allele-genomatched unrelated donors. By classifying them into 5 independent groups based on HLA-C group matching and assumed donor NK cell status, we found that for HLA-C-matched HSCT for AML in HLA-C1/C1 recipients, in whom transient alloreactivity against HLA-C2-negative leukemic cells was expected, the relapse rate was significantly lower than it was in HLA-C-matched HSCT for AML in HLA-C1/C2 recipients (hazard ratio [HR], .72; P = .011). This difference was not observed in HLA-C-matched HSCT for ALL. Compared with HLA-C-matched HSCT, significantly higher mortality was observed in HLA-C1/C1 AML patients who received transplants from HLA-C-mismatched HLA-C1/C1 donors (HR, 1.37; P = .001) and in HLA-C1/C1 ALL patients who received transplants from HLA-C2-positive donors (HR, 2.13; P = .005). In conclusion, donor selection based on leukemic subtype and donor HLA-C group matching improves transplantation outcome after HLA-C-mismatched HSCT.

Comparison of Cyclophosphamide Combined with Total Body Irradiation, Oral Busulfan, or Intravenous Busulfan for Allogeneic Hematopoietic Cell Transplantation in Adults with Acute Lymphoblastic Leukemia.

We conducted a retrospective analysis to compare outcomes in adult patients with acute lymphoblastic leukemia (ALL) who underwent allogeneic hematopoietic cell transplantation (allo-HCT) with conditioning regimens containing cyclophosphamide (CY) in combination with total body irradiation (TBI), oral busulfan (p.o. BU), or intravenous busulfan (i.v. BU). We used data for January 2000 to December 2012 from the Transplant Registry Unified Management Program of the Japan Society of Hematopoietic Cell Transplantation. We identified 2130 patients treated with TBI/CY (n = 2028), p.o. BU/CY (n = 60), or i.v. BU/CY (n = 42). Two-year overall survival (OS) and 2-year relapse-free survival rates were 69.0% and 62.1%, respectively, in the TBI/CY group, 55.9% and 54.2% in the p.o. BU/CY group, and 71.0% and 46.8% in the i.v. BU/CY group. In multivariate analysis, compared with TBI/CY, p.o. BU/CY, but not i.v. BU/CY, was associated with lower OS (hazard ratio [HR], 1.46; P = .047) and a higher incidence of sinusoidal obstruction syndrome (HR, 3.36; P = .030). No between-group differences were seen in the incidence of nonrelapse mortality, relapse, acute graft-versus-host disease (GVHD), or chronic GVHD. We suggest that i.v. BU/CY might be a possible alternative allo-HCT conditioning regimen for adults with ALL who are not suitable for TBI.