HLA-matched sibling transplantation for severe aplastic anemia: impact of HLA DR15 antigen status on engraftment, graft-versus-host disease, and overall survival

The HLA class II DRB1 antigen DR15 (common alleles *1501, *1502) is an important marker in the pathobiology of severe aplastic anemia (SAA). We studied 1204 recipients of HLA-matched sibling bone marrow transplantation for SAA to determine whether HLA DR15 status (as determined by allele-level typing) affected hematopoietic recovery, graft-versus-host disease (GVHD), or overall survival (OS). In multivariate analysis, secondary graft failure rate at 2 years was lower in patients who were HLA DR15+ (hazard ratio = 0.46, P = .01). However, neutrophil recovery at day -28, platelet recovery at day -100, acute GVHD, chronic GVHD, and overall mortality were independent of DR15 status. The 5-year probabilities of OS, after adjusting for age, race, performance score, transplant-conditioning regimen, and year of transplantation, were 78% and 81% for patients who were HLA DR15+ and HLA DR15-, respectively (P = .35). In conclusion, DR15 status is associated with secondary graft failure after HLA-matched sibling bone marrow transplantation for SAA but has no significant impact on survival.     

单倍体相合异基因造血干细胞移植治疗白血病

背景：对于无HLA全相合同胞供者的患者,采用单倍体相合造血干细胞移植面临移植物抗宿主病重、移植相关死亡率高的风险,但通过不同的移植模式,将有可能获取相近的疗效。 目的：观察亲缘HLA单倍体相合异基因造血干细胞移植治疗白血病的疗效,并与亲缘HLA全相合异基因造血干细胞移植相比较。 方法：45例白血病患者分为2组。单倍体组移植方式为外周血或联合骨髓干细胞移植,预处理方案为改良白消安与环磷酰胺或加抗胸腺细胞球蛋白,移植物抗宿主病的预防采用环孢素A+甲氨蝶呤+霉酚酸脂;全相合组移植方式为外周血干细胞移植,预处理方案为BuCY,移植物抗宿主病的预防采用环孢素A+甲氨蝶呤。 结果与结论：两组均获得造血重建时间差异无显著性意义。单倍体及全相合组急性移植物抗宿主病的累积发病率分别为73%对52%(P > 0.05);慢性移植物抗宿主病的累积发病率分别为56%对45%(P > 0.05);移植相关死亡率分别为36%对17%(P > 0.05);单倍体组无复发,全相合组复发2例;两组的预计3年累积无病生存率分别为61%对60%(P > 0.05)。结果提示,亲缘单倍体异基因造血干细胞移植的总体疗效与亲缘全相合异基因造血干细胞移植相似,但中重度急性移植物抗宿主病的发生率较后者为高。     

Excellent Outcome of Allogeneic Hematopoietic Stem Cell Transplantation Using a Conditioning Regimen with Medium-Dose VP-16, Cyclophosphamide and Total-Body Irradiation for Adult Patients with Acute Lymphoblastic Leukemia

We retrospectively evaluated the outcomes of 37 adult patients with acute lymphoblastic leukemia (ALL) undergoing allogeneic hematopoietic stem cell transplantation (allo-SCT) conditioned with medium-dose VP-16 (VP, 30 mg/kg), cyclophosphamide (CY, 120 mg/kg), and fractionated total-body irradiation (TBI, 12 Gy) (medium-dose VP/CY/TBI). The median age of the patients was 26 years. Thirteen patients underwent transplantation from HLA-matched related donors (MRD), 18 patients underwent transplantation from HLA-matched unrelated donors (MUD), and 6 patients underwent transplantation from HLA-mismatched donors (MMD). Thirty-two patients received bone marrow and 4 patients received peripheral blood stem cells. Ten patients were Philadelphia chromosome-positive (Ph⁺) and 35 patients were in complete remission (CR) at transplantation. All of the patients achieved engraftment, and grade 3 organ toxicity before engraftment occurred in 27 patients. Grade II-III acute graft-versus-host disease (GVHD) and chronic GVHD (cGVHD) occurred in 15 and 18 patients, respectively. No patient developed grade IV acute GVHD (aGVHD) or died of GVHD. At median follow-up of 35.1 months, 32 patients were alive and all Ph⁺ patients were alive. Three patients died of relapse and 2 died of transplant-related mortality (TRM). The actuarial 3-year overall survival (OS) rate, relapse rate, and TRM rate were 89.2%, 8.1%, and 5.4%, respectively. Non-CR at transplantation, MRD, and no aGVHD were significant adverse prognostic factors for survival. Medium-dose VP/CY/TBI for adult ALL patients was associated with lower relapse rate and no increase in toxicity, resulting in better survival.     

Graft-versus-tumor effect according to type of graft-versus-host disease defined by National Institutes of Health consensus criteria and associated outcomes

The impact of National Institutes of Health consensus criteria (NCC) graft-versus-host disease (GVHD) on survival has rarely been investigated in a large cohort of patients with GVHD presenting before and after day 100 posttransplantation. We retrospectively investigated 775 patients who underwent allogeneic stem cell transplantation and assessed the GVHD effects on survival by the time-dependent covariates in Cox proportional hazards regression models. Using the NCC, the patients were classified into 4 groups: (1) no GVHD (n?= 251); (2) acute GVHD (aGVHD) only (n = 199), including 26 patients with late aGVHD; (3) classic chronic GVHD (cGVHD; n = 232); and (4) overlap syndrome (OS; n = 93). Multivariate analyses showed that classic cGVHD (hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.27-0.77) and OS (HR, 0.52; 95% CI, 0.28-0.96) were associated with significantly decreased risk of relapse, whereas aGVHD only was not associated with relapse rate (HR, 1.11; 95% CI, 0.76-1.63). All aGVHD events, including the period of aGVHD in patients who developed cGVHD after aGVHD, also did not affect the risk of relapse (HR, 0.74; 95% CI, 0.49-1.12). All types of GVHD were significantly associated with higher nonrelapse mortality in common. Finally, patients with aGVHD only had significantly lower overall survival and disease-free survival compared with those without GVHD, in contrast to favorable survival outcomes in patients with cGVHD without previous aGVHD. This study demonstrates that NCC GVHD type is associated with different graft-versus-tumor effects. Further studies are needed to investigate risk factors, pathogenesis, and biomarkers for each type of NCC GVHD.     

Young Female Donors Do Not Increase the Risk of Graft-versus-Host Disease or Impact Overall Outcomes in Pediatric HLA-Matched Sibling Hematopoietic Stem Cell Transplantation

Optimal donor selection is critical in hematopoietic stem cell transplantation (HSCT). Donor–recipient sex mismatch, donor age, and female donor–donor parity are known to impact graft-versus-host disease (GVHD) and outcomes in adults. Minor histocompatibility antigens encoded by the human Y chromosome can result in specific antibody formation in some female donors, may increase in frequency with increasing donor age, and may be contributory to the increased incidence of GVHD. To better understand the role of donor age/sex and sex matching in HSCT outcomes, we conducted a retrospective study of pediatric patients receiving their first myeloablative sibling donor HSCT (n?=?244) from 1998 to 2012. Observed rates of GVHD were low: 17% of patients surviving past engraftment (n?=?243) developed grades II to IV acute GVHD (aGVHD) and 14% surviving ≥ 100 days (n?=?229) developed chronic GVHD (cGVHD). On multivariate analysis the risk of aGVHD, cGVHD, and death increased with patient age as expected. Female donor sex and sex mismatch (female donor–male recipient) had no impact on the development of aGVHD. cGVHD was increased with female donors only if the donor was ≥12 years old. No cGVHD was observed among 109 patients aged < 10 years who received a 6/6 HLA-matched marrow HSCT, regardless of donor age or sex. Survival was mostly driven by diagnosis. Results suggest that in pediatric HSCT, young HLA-matched siblings are equivalently good donors regardless of sex or donor–recipient sex mismatch.     

Fludarabine-Melphalan Conditioning for AML and MDS: Alemtuzumab Reduces Acute and Chronic GVHD without Affecting Long-Term Outcomes

The purpose of this study was to determine the effect of alemtuzumab on treatment-related mortality (TRM), relapse, overall survival (OS), and disease-free survival (DSF) in patients with acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS) undergoing reduced intensity conditioning (RIC). We compared the outcome of 95 patients treated at the University of Chicago with fludarabine melphalan (Flu + Mel) + alemtuzumab conditioning and 59 patients treated at the M.D. Anderson Cancer Center with Flu + Mel conditioning. Both groups had similar patient and donor characteristics. There were no significant differences in TRM, relapse, survival, and DFS between the 2 groups. The incidence of acute graft-versus-host disease (aGVHD) grade II-IV (relative risk [RR] 5.5, P < .01) and chronic GVHD (cGVHD) (RR 6.6, P < .01) were significantly lower in patients receiving alemtuzumab. The addition of alemtuzumab to an RIC regimen dramatically reduces the incidence of aGVHD and cGVHD in patients with AML and MDS undergoing allogeneic transplantation. TRM, relapse risk, OS and DFS are not affected.     

无关供者异基因造血干细胞移植治疗骨髓增生异常综合征9例患者临床分析

目的探讨无关供者异基因造血干细胞移植(UD-HSCT)治疗骨髓增生异常综合征(MDS)的疗效和可行性。方法MDS患者9例,其中男性6例,女性3例;年龄7～46岁,中位年龄30岁。其中难治性贫血(RA)1例,难治性血细胞减少伴有多系发育异常(RCMD)2例,难治性贫血伴有原始细胞过多-2(RAEB-2)5例,MDS进展为急性髓系白血病(MDS-AML)1例。接受UD-HSCT治疗的MDS患者中外周血造血干细胞移植(PBSCT)8例,骨髓移植(BMT)1例。供受者HLA高分辨配型10/10位点相合4例、9/10位点相合4例、7/10位点相合1例。预处理方案为BU+CY+Flud+Ara-C+ATG 8例、BU+Mel+Flud+Ara-C+ATG 1例,移植物抗宿主病(GVHD)预防方案为FK506+MTX+MMF 8例、CsA+MTX+MMF 1例。结果9例患者均获得造血重建,中性粒细胞≥0.5×109/L和血小板≥20×109/L的中位时间分别为移植后15(11～20)d和23(8～32)d。6例患者发生急性GVHD(aGVHD),其中Ⅰ度4例,Ⅱ度2例,5例患者发生局限型慢性GVHD(cGVHD)。中位随访20.3(6.4～50.0)个月,1例患者移植后14个月复发死亡,其余8例患者中位随访27.9(6.4～50.0)个月,均无病存活,总体生存率(OS)及无病生存率(DFS)均为85.7%±13.2%。结论UD-HSCT治疗MDS安全有效,在无同胞全合供者时,无关供者也可以作为此类患者有效治疗选择。     

Assessment of Individual versus Composite Endpoints of Acute Graft-versus-Host Disease in Determining Long-Term Survival after Allogeneic Transplantation

The overall composite of graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS), defined as survival free of grade III-IV acute GVHD (aGVHD), chronic GVHD (cGVHD) requiring systemic immunosuppressive therapy (IST), or relapse, has emerged as a useful composite in clinical trials and to capture clinically meaningful events that impact quantity and quality of survival after allogeneic hematopoietic cell transplantation (HCT). We reviewed 565 consecutive patients aged ≥18 years undergoing HCT for hematologic malignancy to analyze how baseline incidence, specifics of clinical definitions, and proposed reductions in any one individual event may dynamically alter the overall performance of the composite To determine the relative impact of each GRFS event (excluding death), we accounted for competing risks using Fine and Gray methods, and correlated each event with overall survival (OS) using Kaplan-Meier methods. The consequences of modulating individual or composite endpoints on OS, such as hypothesized reductions of events of an HCT interventional trial, were examined using Monte Carlo simulations. The median age of the cohort was 54 years (range, 18 to 73 years). The majority of patients received HLA-matched unrelated donor HCT (53%), consisting of peripheral blood stem cell grafts (90%) after myeloablative conditioning (68%). Relapse conferred the greatest risk for death (hazard ratio [HR], 7.89; 95% confidence interval [CI], 5.83 to 10.69), followed by grade III-IV aGVHD (HR, 6.16; 95% CI, 4.42 to 8.56) and cGVHD requiring IST (HR, 1.69; 95% CI, 1.16 to 2.46). The overall GRFS composite correlated with an HR of 4.81 (95% CI, 3.61 to 6.41), which was lower compared with either relapse or grade III-IV aGVHD. Statistical simulations found that modulating the combined risk of both relapse and grade III-IV aGVHD predicted the greatest change in 5-year OS. These simulations suggest that GRFS as currently defined may be less optimal for correlating with OS, and further refinement of composite endpoints is needed. Nonetheless, composite endpoints may be particularly helpful in mitigating potential difficulties in interpretation when competing risks are present, most commonly seen in HCT studies.     

Alternate donor hematopoietic cell transplantation (HCT) in non-Hodgkin lymphoma using lower intensity conditioning: a report from the CIBMTR

We analyzed the outcomes of 248 (61% male) adult recipients of HLA-matched unrelated and HLA-mismatched related donor hematopoietic cell transplantation (HCT) for non-Hodgkin lymphoma (NHL) after reduced or lower intensity conditioning (RIC), reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) from 1997 to 2004. Median age was 52 (range: 18-72 years); 31% had a Karnofsky performance score <90. Follicular NHL (43%) was the major histology. Incidence of grades II-IV acute graft-versus-host disease (aGVHD) was 43% at 100 days; and chronic GVHD (cGVHD) was 44% at 3 years. Treatment-related mortality (TRM) at 100 days was 24%. Three-year overall survival (OS) and progression-free survival (PFS) were 41% and 32%, respectively. In multivariate analysis, use of antithymocyte globulin (ATG) and HLA mismatch were associated with increased TRM. High-grade histology, ATG use, and chemotherapy resistance were associated with lower PFS. Older age, shorter interval from diagnosis to HCT, non-total body irridiation (TBI) conditioning regimens, ex?vivo T cell depletion, and HLA-mismatched unrelated donors were associated with mortality. GVHD did not influence relapse or PFS. Older age, aggressive histology, and chemotherapy resistance correlated with poorer survival. For selected patients with NHL, lack of an available sibling donor should not be a barrier to allogeneic HCT.     

Severe acute graft-vs-host disease in a patient with acute monocytic leukemia having a recombination event between HLA-A/B loci from a multiple recombinant family

Human leukocyte antigen (HLA) recombination, particularly multiple recombinations can produce novel haplotypes, thereby complicating donor-recipient selection and possibly inducing severe graft-vs-host disease (GVHD) after nonfully matched allogeneic hematopoietic stem cell transplantation. Here, we report for the first time that a 30-year-old female acute monocytic leukemia patient with an HLA-A/B recombinant haplotype, who has three unmatched and one HLA-B/DRB1 recombinant haplotype siblings, presented grade IV acute GVHD (aGVHD) after transplantation from a sibling with a single allele only mismatch at the classical HLA-A locus. Furthermore, using a new three-dimensional structure modeling application, we inferred that the structural differences in peptide-binding and T-cell receptor interaction sites can significantly change the immunogenicity of mismatched HLA molecules, potentially one of the main causes of aGVHD.     

Peripheral blood grafts from unrelated donors are associated with increased acute and chronic graft-versus-host disease without improved survival.

Few studies have tested the benefits of using peripheral blood stem cell (PBSC) grafts versus bone marrow (BM) grafts for unrelated donor transplantation. Yet there has been a substantial change in clinical practice, with increasing numbers of adults receiving unrelated donor PBSC grafts. We compared outcomes after 331 PBSC and 586 BM transplants in adults with leukemia and myelodysplastic syndrome (MDS) who were followed for a median of 3 years after transplantation. PBSC recipients were less likely to have chronic myelogenous leukemia (CML) and more likely to have MDS, to have poor performance scores, and to be transplanted more recently. Outcomes were analyzed using Cox regression models. Rates of grades 2-4 acute graft-versus-host disease (GVHD) (58% versus 45%, P < .001) and chronic GVHD (cGVHD) (56% versus 42%, P < .001) were significantly higher with PBSC than with BM transplants. Rates of grade II-IV aGVHD were similar with PBSC and BM transplants. The 3-year probabilities of treatment-related mortality (TRM), leukemia recurrence, leukemia-free, and overall survival (OS) were similar in the 2 groups with 3-year leukemia-free survival rates of 30% and 32% after transplantation of PBSC and BM, respectively. Unlike results after HLA-matched sibling donor PBSC transplants, we did not identify a survival advantage with PBSC grafts in patients receiving unrelated donor transplants for advanced leukemia. The higher rate of cGVHD after PBSC transplants and, consequently, more frequent late adverse events warrant extended follow up of PBSC recipients.     

Impact of T Cell Dose on Outcome of T Cell-Replete HLA-Matched Allogeneic Peripheral Blood Stem Cell Transplantation

Data on whether the T cell dose of allogeneic peripheral blood stem cell (PBSC) products influences transplantation outcomes are conflicting. Using the Center for International Blood and Marrow Transplant Research database, we identified 2736 adult patients who underwent first allogeneic PBSC transplantation for acute leukemia or myelodysplastic syndrome between 2008 and 2014 using an HLA-matched sibling donor (MSD) or an 8/8-matched unrelated donor (MUD). We excluded ex vivo and in vivo T cell-depleted transplantations. Correlative analysis was performed between CD3⁺ T cell dose and the risk of graft-versus-host-disease (GVHD), relapse, nonrelapse mortality (NRM), disease-free survival (DFS), and overall survival (OS). Using maximum likelihood estimation, we identified CD3⁺ T cell dose cutoff that separated the risk of acute GVHD (aGVHD) grade II-IV in both the MSD and MUD groups. A CD3⁺ T cell dose cutoff of 14 × 10⁷ cells/kg identified MSD/low CD3⁺ (n = 223) and MSD/high CD3⁺ (n = 1214), and a dose of 15 × 10⁷ cells/kg identified MUD/low CD3⁺ (n = 197) and MUD/high CD3⁺ (n = 1102). On univariate analysis, the MSD/high CD3⁺ group had a higher cumulative incidence of day +100 aGVHD grade II-IV compared with the MSD/low CD3⁺ group (33% versus 25%; P = .009). There were no differences between the 2 groups in engraftment rate, risk of aGVHD grade III-IV or chronic GVHD (cGVHD), NRM, relapse, DFS, or OS. The MUD/high CD3⁺ group had a higher cumulative incidence of day +100 aGVHD grade II-IV compared with the MUD/low CD3⁺ group (49% versus 41%; P = .04). There were no differences between the 2 groups in engraftment rate, risk of severe aGVHD or cGVHD, NRM, relapse, DFS, or OS. Multivariate analysis of the MSD and MUD groups failed to show an association between CD3⁺ T cell dose and the risk of either aGVHD grade II-IV (P = .10 and .07, respectively) or cGVHD (P = .80 and .30, respectively). Subanalysis of CD4⁺ T cells, CD8⁺ T cells, and CD4+/CD8+ ratio failed to identify cutoff values predictive of transplantation outcomes; however, using the log-rank test, the sample size was suboptimal for identifying a difference at this cutoff cell dose. In this registry study, the CD3⁺ T cell dose of PBSC products did not influence the risk of aGVHD or cGVHD or other transplantation outcomes when using an MSD or an 8/8-matched MUD. Subset analyses of CD4⁺ and CD8⁺ T cell doses were not possible given our small sample size.     

Comparison of outcomes after HLA-matched sibling and unrelated donor transplantation for children with high-risk acute lymphoblastic leukemia

We compared outcomes after 94 HLA-matched sibling, 168 unrelated donor bone marrow (BM; n = 81 matched and n = 88 mismatched), and 86 cord blood transplantations in patients age 1 to 15 years with acute?lymphoblastic leukemia (ALL) in second complete remission (CR). All patients had their first BM relapse within 3 years from diagnosis. Cox regression models were constructed to examine for differences in transplant outcome by donor source. Risks of grade 2 to 4 acute graft-versus-host disease (aGVHD) and chronic graft-versus-host disease (cGVHD), when compared to HLA-matched sibling transplants, were higher after matched unrelated donor BM (relative risk [RR], 2.42; P = .001; RR, 5.12; P < .001, respectively), mismatched BM (RR, 3.24; P < .001; RR, 5.19; P < .001, respectively), and cord blood (RR, 2.67; P < .001; RR, 2.54; P = .024, respectively) transplants. Although nonrelapse mortality was higher after transplantation of mismatched unrelated donor BM and cord blood, there were no differences in leukemia-free survival (LFS) between HLA-matched sibling and any of the unrelated donor transplantations. The 3-year probabilities of LFS were 50% after HLA-matched sibling and 44% after matched unrelated BM, and 44% after mismatched unrelated BM and 43% after cord blood transplantation. Our observations support transplantation of BM or cord blood from a suitably matched unrelated donor or cord blood for patients without an HLA-matched sibling with ALL in second CR.     

HLA单倍体与全相合异基因造血干细胞移植治疗恶性血液病

背景：异基因造血干细胞移植是治疗恶性血液病的一种非常有效的方法。单倍体相合的造血干细胞移植扩大了移植的应用范围,是无HLA相合供者患者的一种重要选择。 目的：比较HLA单倍体相合与全相合异基因造血干细胞移植治疗恶性血液病的临床疗效。 方法：回顾性分析接受异基因造血干细胞移植79例恶性血液病患者的临床资料,其中HLA单倍体相合组26例、全相合组53例,对比两组受者移植物抗宿主病的发生率、复发率、2年生存率等。 结果与结论：78例受者获得完全、持久供者干细胞植入;1例受者在移植后28 d尚未植入,后因感染死亡。两组慢性移植物抗宿主病发生率、复发率和2年无病生存率差异无显著性意义(P > 0.05)。单倍体相合组急性移植物抗宿主病发生率高于全相合组(P < 0.05);2年总生存率低于全相合组(P < 0.05)。提示血缘HLA单倍体相合移植治疗恶性血液病的安全性及疗效接近于全相合移植,在缺乏HLA相合供者的情况下,行HLA单倍体相合造血干细胞移植治疗恶性血液病是切实可行的选择。     

Development of Grade II Acute Graft-versus-Host Disease Is Associated with Improved Survival after Myeloablative HLA-Matched Bone Marrow Transplantation using Single-Agent Post-Transplant Cyclophosphamide

Post-transplant cyclophosphamide (PTCy) can be used as the sole immunosuppression after myeloablative conditioning (MAC) for HLA-matched bone marrow transplantation (BMT). However, the effects of graft-versus-host disease (GVHD) with this platform are undefined. We retrospectively analyzed 298 consecutive adult patients with hematologic malignancies who engrafted after MAC HLA-matched sibling donor (MSD; n = 187) or HLA-matched unrelated donor (MUD; n = 111) T-cell–replete BMT with PTCy 50 mg/kg on days +3 and +4. After MSD and MUD BMT, 35% and 57% of patients, respectively, developed grade II acute GVHD (aGVHD) by 100 days, 11% and 14% grade III to IV aGVHD by 100 days, and 9% and 16% chronic GVHD (cGVHD) by 1 year. In landmark analyses at 100 days after HLA-matched BMT, 4-year overall survival (OS) and progression-free survival (PFS) were 57% (95% confidence interval [CI], .49 to .67) and 40% (95% CI, .31 to .51) in patients without grades II to IV aGVHD, and 68% (95% CI, .59 to .78) and 54% (95% CI, .44 to .65) in patients with grade II aGVHD. In adjusted time-dependent multivariable analyses, grade II aGVHD was associated with improved OS (hazard ratio, .58; 95% CI, .37 to .89; P = .01) and PFS (hazard ratio, .50; 95% CI, .34 to .74; P < .001) after HLA-matched BMT with PTCy. The ability of PTCy to limit grades III to IV aGVHD and cGVHD while maintaining grade II aGVHD may contribute to its effectiveness, and further attempts to reduce aGVHD may be detrimental.     

Current donor selection strategies for allogeneic hematopoietic cell transplantation

Since the first allogeneic hematopoietic stem cell transplantation (HCT) was performed by Dr. E. Donnall Thomas in 1957, the field has advanced with new stem cell sources, immune suppressive regimens, and transplant protocols. Stem cells may be collected from bone marrow, peripheral or cord blood from an identical twin, a sibling, or a related or unrelated donor, which can be human leukocyte antigen (HLA) matched, mismatched, or haploidentical. Although HLA matching is one of the most important criteria for successful allogeneic HCT (allo-HCT) to minimize graft vs host disease (GVHD), prevent relapse, and improve overall survival, the novel immunosuppressive protocols for GVHD prophylaxis offered improved outcomes in haploidentical HCT (haplo-HCT), expanding donor availability for the majority of HCT candidates. These immunosuppressive protocols are currently being tested with the HLA-matched and mismatched donors to improve HCT outcomes further. In addition, fine-tuning the DPB1 mismatching and discovering the B leader genotype and mismatching may offer further optimization of donor selection and transplant outcomes. While the decision about a donor type largely depends on the patient’s characteristics, disease status, and the transplant protocols utilized by an individual transplant center, there are general approaches to donor selection dictated by donor-recipient histocompatibility and the urgency for HCT. This review highlights recent advances in understanding critical factors in donor selection strategies for allo-HCT. It uses clinical vignettes to demonstrate the importance of making timely decisions for HCT candidates.     

Outcomes following HSCT Using Fludarabine,Busulfan, and Thymoglobulin: A Matched Comparison to Allogeneic Transplants Conditioned with Busulfan and Cyclophosphamide

We have reported a lower incidence of acute graft-versus-host disease (aGVHD) with a novel conditioning regimen using low-dose rabbit antithymocyte globulin (ATG; Thymoglobulin [TG]) with fludarabine and intravenous busulfan (FluBuTG). To assess further this single-center experience, we performed a retrospective matched-pair analysis comparing outcomes of adult patients transplanted using the FluBuTG conditioning regimen with matched controls from patients reported to the CIBMTR receiving a first allogeneic hematopoietic stem cell transplant (HCT) after standard oral busulfan and cyclophosphamide (BuCy). One hundred twenty cases and 215 matched controls were available for comparison. Patients receiving FluBuTG had significantly less treatment related mortality (TRM; 12% versus 34%, P < .001) and grades II-IV aGVHD (15% versus 34%, P < .001) compared to BuCy patients. The risk of relapse was higher in the FluBuTG patients (42% versus 20%, P < .001). The risks of chronic GVHD (cGVHD) and disease free survival (DFS) were similar in the cases and controls. These results suggest that the novel regimen FluBuTG decreases the risk of aGVHD and TRM after HLA-identical sibling HSCT, but is associated with an increased risk of relapse, resulting in similar DFS. Whether these conditioning regimens may be more suitable for specific patient populations based on relapse risk requires testing in prospective randomized trials.     

Treatment of Acute Leukemia with Unmanipulated HLA-Mismatched/Haploidentical Blood and Bone Marrow Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains one of the best therapeutic options to cure acute leukemia (AL). However, many patients have no human leukocyte antigen (HLA)-matched donor. Recently, we developed a new method for HLA-mismatched/haploidentical transplantation without in vitro T cell depletion (TCD). This method combined granulotyce-colony stimulating factor (G-CSF)-primed bone marrow and peripheral blood with intensive immunosuppression. We analyzed the outcome of 250 consecutive patients with AL who underwent HLA-mismatched/haploidentical transplantation with 1-3 mismatched loci of HLA-A, B, and DR from family donors via our new transplant protocol. Two hundred forty-nine patients achieved sustained, full donor chimerism. The incidence of grade 2-4 acute graft-versus-host disease (aGVHD) was 45.8%, and that of grades 3 and 4 was 13.4%, which was not associated with the extent of HLA disparity. The cumulative incidence of total chronic GVHD (cGVHD) was 53.9% and that of extensive cGVHD was 22.6% in 217 evaluable patients. One hundred forty-one of the 250 patients survived free of disease recurrence at a median of 1092 days (range: 442-2437 days) of follow-up. Seventeen patients received DLI as a treatment for relapse after transplantation and 7 patients achieved leukemia-free survival (LFS). The 3-year probability of LFS for acute myelogenous leukemia (AML) was 70.7% and 55.9%, and for acute lymphoblastic leukemia (ALL) it was 59.7% and 24.8% in standard-risk and high-risk groups, respectively. Lower LFS were associated with diagnosis of acute leukemia in the high-risk group (P = .001, relative risk [RR], 95% confidence interval [CI]: 2.94[1.535-5.631]) and the occurrence of aGVHD of grades 3 and 4 (P = .004). HLA-mismatched/haploidentical HSCT was feasible with unmanipulated blood and bone marrow harvest.     

Reduced-intensity transplantation for patients with myelodysplastic syndrome achieves durable remission with less graft-versus-host disease.

Reduced-intensity allogeneic transplantations for myelodysplastic syndrome (MDS) patients have been limited by significant graft-versus-host disease (GVHD), treatment-related mortality, and disease relapse. We treated 18 MDS patients ineligible for standard allogeneic transplantation with a preparative regimen of photopheresis day -7 and -6, pentostatin 4 mg/m(2) by continuous infusion day -5 and -4, and total body irradiation 600 cGy in 3 fractions day -3 and -2, followed by allogeneic stem cell infusion from 6/6 or 5/6 HLA-matched related donors or 6/6 HLA-matched unrelated donors. GVHD prophylaxis consisted of cyclosporin A and a short course of methotrexate. The median age was 54 years (range, 30-70 years). Diagnoses included refractory anemia (n = 2), refractory anemia with ringed sideroblasts (n = 2), refractory anemia with excess blasts (n = 10), refractory anemia with excess blasts in transformation (n = 3), and chronic myelomonocytic leukemia (n = 1). Sixteen of 18 patients developed full donor chimerism with no day +100 transplant-related mortality. Grade II to IV acute GVHD and extensive chronic GVHD developed in 19% and 18% of patients, respectively. Disease relapse occurred in 2 patients. At a median follow-up of 14 months (range, 1-35 months), the 1-year failure-free and overall survival were 64% and 65%, respectively. Our photopheresis and pentostatin-based reduced-intensity preparative regimen for allogeneic bone marrow transplantation in high-risk MDS patients achieves successful donor engraftment and disease remission with less transplant toxicity and grade II to IV acute GVHD.     

Donor Selection for Killer Immunoglobulin-like Receptors B Haplotype of the Centromeric Motifs Can Improve the Outcome after HLA-Identical Sibling Hematopoietic Stem Cell Transplantation

After hematopoietic stem cell transplantation (HSCT), natural killer (NK) cell alloreactivity in HLA cells of recipients is regulated by killer immunoglobulin-like receptors (KIRs) on donor NK cells. The effect of KIRs on HSCT outcomes is controversial, particularly in those undergoing HLA-identical sibling HSCT. In this study, effects of KIR and HLA genotypes on the HSCT outcome were investigated in a 5-year retrospective study comprising 219 patient-donor pairs undergoing HLA-identical sibling HSCT for myeloid and lymphoid malignancies. We found that 39.7% (87 of 219) of these pairs, which were KIR mismatched, had better overall survival (OS) and reduced grade III to IV acute graft-versus-host disease (aGVHD), especially in acute myeloid leukemia (AML) patients. Bx1 donor KIR genotype with haplotype B on a telomeric region was a risk factor for the OS and relapse-free survival (RFS). Donor centromeric (c) and telomeric (t) KIR haplotype analysis showed that donor KIR cB-tA/tB was associated with improved OS and RFS compared with cA-tA or cA-tB. Furthermore, donor KIR B haplotype of the centromeric motifs (Cen-B) was an independent beneficial factor in improving OS and RFS and in protecting from relapse after HSCT. In AML patients, the occurrence of aGVHD was significantly lower in HLA-C1 group compared with that in HLA-C2 group, although such effect was not observed in patients with acute lymphoblastic leukemia or chronic myelogenous leukemia. Our results suggest that KIR could impact outcome and donor KIR haplotype with Cen-B confer significant survival benefits to HLA-identical sibling HSCT.