HLA-identical Sibling Hematopoietic Stem Cell Research Articles

Nonmyeloablative HLA-Identical Sibling Donor Transplantation for Children and Young Adults with Sickle Cell Disease: Interim Results of the SUN Multicenter Phase II Trial

Background: HLA-identical sibling hematopoietic stem cell transplant (HSCT) using myeloablative chemotherapy conditioning is a proven cure for sickle cell disease (SCD), but is associated with serious short and long-term toxicities. Additionally graft versus host disease (GVHD) can complicate care post-HSCT and contribute to mortality. Given these concerns many pediatric hematologists and families are reluctant to pursue HSCT for SCD. Nonmyeloablative HSCT resulting in stable mixed chimerism has been demonstrated to abrogate the SCD phenotype in adults. Data on outcomes of this approach to decrease toxicities and achieve cure in children remains scarce.Objective: To evaluate event-free survival (EFS), toxicity, health-related quality of life (HRQL), and transfusion burden among pediatric patients with SCD using a chemotherapy-free nonmyeloablative regimen.Methods/design: Children and young adults with SCD were prospectively enrolled in the Sickle transplant Using a Nonmyeloablative approach (SUN) multicenter clinical trial (NCT03587272). Six Sickle Cell Transplant Advocacy and Research Alliance (STAR) sites in the United States and Canada enrolled patients. The conditioning regimen consisted of alemtuzumab IV (0.03mg/kg on Day -7, 0.1mg/kg on Day -6, 0.3mg/kg on Days -5 to -3), low-dose total body irradiation with gonadal shielding (300 cGY on day -2), peripheral blood stem cells from an HLA-identical sibling, and sirolimus for at least one year. Baseline HRQL was compared with scores at day +30 and day +100 post-HSCT using the PedsQL and PROMIS measures. EFS was defined by any of the following events: death, graft failure (myeloid donor chimerism <10%), or GVHD.Results: All 30 of the patients planned for the primary endpoint of EFS have been enrolled. As of 7/20/2021, 24 patients are greater than 100 days post-HSCT with a median follow-up of 365 days (range 189-1105). The median age of this group at time of transplant was 13.5 years (range 2-22). All patients had neutrophil recovery (ANC >500/ul x 3 days) at a median of 21.5 days (range 0-29). Eleven patients (46%) did not require any platelet transfusions. Median transplant hospitalization was 16.5 days (range 14-43). Seven patients (29%) were again hospitalized (median 4 days, range 1-26). Three patients had secondary graft rejection at Day +71, +91, and +92 with no major complications and autologous recovery resulting in an EFS of 87.5% (Figure 1). Three additional patients have stable low donor chimerism (myeloid chimerism 11%, 38%, and 47%). The remaining 18 patients (75%) are disease-free and have robust donor engraftment (72-100% myeloid chimerism). Nine of these patients are >1 year post-HSCT and off sirolimus. Overall survival is 100% with no acute or chronic GVHD. Figure 2 shows total PedsQL scores during the peri-transplant time period. The median change in day +30 scores compared to baseline was 0 (IQR -7, +10), p=0.66. The median change in day +100 scores compared to baseline was +5 (IQR 0, +10), p=0.02.Conclusions: Outcomes of pediatric nonmyeloablative HLA-identical sibling HSCT for SCD appear similar to the larger adult experience with a GVHD-free, rejection-free survival of >80%. Importantly, patients have no worsening of their quality of life in the first month post-HSCT and already an improvement at day +100, suggesting that the short-term toxicities experienced by patients transplanted with this regimen are minimal. The majority of patients achieve disease resolution with no GVHD, but graft failure incidence appears higher than with myeloablative HSCT. Given the low intensity of this approach, a reasonable strategy may be to reserve myeloablation for a second transplant in the minority of patients who experience graft failure. [Display omitted] DisclosuresRangarajan: Medexus (Treosulfan): Consultancy, Honoraria. Guilcher: BlueBirdBio: Research Funding; Project Sickle Cure Study: Other: Principal Investigator, Research Funding. OffLabel Disclosure:alemtuzumab and sirolimus were used off-label as part of the studied transplant regimen

The impact of donor and recipient KIR genes and KIR ligands on the occurrence of acute graft-versus-host disease and graft survival after HLA-identical sibling hematopoietic stem cell transplantation

After allogeneic hematopoietic stem cell transplantation (allo-HSCT), donor natural killer (NK) cells trigger alloreactions against potential recipient cells by their killer immunoglobulin-like receptors (KIRs). This study investigated whether KIR/HLA genotypes and KIR haplotypes of donors and recipients exhibit a critical function in the prevalence of acute graft-versus-host disease (aGVHD) and persistence of the graft after HLA-identical sibling allo-HSCT for patients with hematological malignancies. We studied KIR and HLA genotypes in 115 related donors and recipients (56 patients with AML and 59 patients with ALL) who had received allo-HSCT from HLA-matched sibling donors. We evaluated 17 KIR genes and some alleles, including their ligands, using the PCR-SSP assay. KIR gene frequency results between donors and recipients showed that donors had more activating KIR than their recipients. Chi-square comparison of KIR genotype frequencies in donors versus recipients revealed a significant difference (P < 0.001). We found a survival association between the donor lacking and the recipient having group B KIR haplotypes, although this was not statistically significant. This study suggests that we could exploit NK cell alloreactivity as a part of the optimization of donor selection and potential immunotherapeutic regimens to help facilitate good engraftment and reduce the risk of aGVHD incidence after allo-HSCT.

The case for HLA-identical sibling hematopoietic stem cell transplantation in children with symptomatic sickle cell anemia.

This article has a companion Counterpoint by DeBaun and Clayton.

Sickle cell disease: an international survey of results of HLA-identical sibling hematopoietic stem cell transplantation

AbstractDespite advances in supportive therapy to prevent complications of sickle cell disease (SCD), access to care is not universal. Hematopoietic cell transplantation is, to date, the only curative therapy for SCD, but its application is limited by availability of a suitable HLA-matched donor and lack of awareness of the benefits of transplant. Included in this study are 1000 recipients of HLA-identical sibling transplants performed between 1986 and 2013 and reported to the European Society for Blood and Marrow Transplantation, Eurocord, and the Center for International Blood and Marrow Transplant Research. The primary endpoint was event-free survival, defined as being alive without graft failure; risk factors were studied using a Cox regression models. The median age at transplantation was 9 years, and the median follow-up was longer than 5 years. Most patients received a myeloablative conditioning regimen (n = 873; 87%); the remainder received reduced-intensity conditioning regimens (n = 125; 13%). Bone marrow was the predominant stem cell source (n = 839; 84%); peripheral blood and cord blood progenitors were used in 73 (7%) and 88 (9%) patients, respectively. The 5-year event-free survival and overall survival were 91.4% (95% confidence interval, 89.6%-93.3%) and 92.9% (95% confidence interval, 91.1%-94.6%), respectively. Event-free survival was lower with increasing age at transplantation (hazard ratio [HR], 1.09; P < .001) and higher for transplantations performed after 2006 (HR, 0.95; P = .013). Twenty-three patients experienced graft failure, and 70 patients (7%) died, with the most common cause of death being infection. The excellent outcome of a cohort transplanted over the course of 3 decades confirms the role of HLA-identical sibling transplantation for children and adults with SCD.

Donor lymphocyte count and thymic activity predict lymphocyte recovery and outcomes after matched-sibling hematopoietic stem cell transplant

Delayed immune recovery is a characteristic feature of allogeneic hematopoietic stem cell transplantation in adult recipients. Although recipient thymic T-cell neogenesis contributes to T-cell regeneration after transplantation, thymic recovery in the transplant recipient decreases with increasing age, and is diminished by intensive preconditioning regimens and graft-versus-host disease. In adult recipients, most events that determine transplant success or failure occur during the period when the majority of circulating T cells is derived from the donor's post thymic T-cell repertoire. As a result, the make-up of the donor lymphocyte compartment may strongly influence immune recovery and transplant outcomes. The aim of this study was to examine donor lymphocyte counts in a series of patients undergoing an allogeneic hematopoietic stem cell transplant to identify the potential contribution of donor regulatory and conventional T lymphocyte populations to immune recovery and transplant outcomes. We examined donor lymphocyte subset counts in relation to post-transplant lymphocyte recovery and transplant events in 220 consecutive myeloablative, T-cell-depleted, HLA-identical sibling hematopoietic stem cell transplant recipients with hematologic malignancies. In a multivariate analysis, absolute numbers of donor CD4(+) recent thymic emigrants were associated with overall survival (P=0.032). The donors' absolute lymphocyte count and thymic production of regulatory T cells were both associated with extensive chronic graft-versus-host disease (P=0.002 and P=0.022, respectively). In conclusion, these results identify donor immune characteristics that are associated with lymphocyte recovery, extensive chronic graft-versus-host disease, and survival in the recipient following allogeneic hematopoietic stem cell transplantation. The study reported here was performed using peripheral blood samples drawn from donors and patients enrolled in the ClinicalTrials.gov-registered trials NCT00001623, NCT00001873, NCT00353860, NCT00066300, NCT00079391, and NCT00398346.

Genotypes and haplotypes in the 3′ untranslated region of the HLA‐G gene and their association with clinical outcome of hematopoietic stem cell transplantation for beta‐thalassemia

Polymorphisms in the 3' untranslated region (3'UTR) of HLA-G, an important player in immunological tolerance, could be involved in post-transcriptional expression control, and their association with different clinical immune-related conditions including autoimmunity and transplantation is of mounting interest. Most studies have focused on a 14 base pair (bp) insertion/deletion (ins/del), while additional single-nucleotide polymorphisms (SNPs) in the HLA-G 3'UTR have been described but not extensively investigated for their clinical relevance. Here we have comparatively studied the association between 3'UTR haplotypes of HLA-G, or the 14 bp ins/del, with clinical outcome of HLA-identical sibling hematopoietic stem cell transplantation (HSCT) in 147 Middle Eastern beta-thalassemia patients. Sequence based typing of 3'UTR HLA-G polymorphisms in the patients and in 102 healthy Italian blood donors showed strong linkage disequilibrium between the 14 bp ins/del and five 3'UTR SNPs, which together could be arranged into eight distinct haplotypes based on expectation-maximization studies, with four predominant haplotypes (UTRs1-4). After HSCT, we found a moderate though not significant association between the presence of UTR-2 in double dose and protection from acute graft versus host disease (hazard ratio (HR) 0.45, 95% confidence intervals (CI): 0.14-1.45; P = 0.18), an effect that was also seen when the corresponding 14 bp ins/ins genotype was considered alone (HR 0.42, 95% CI: 0.16-1.06; P = 0.07). No association was found with rejection or survival. Taken together, our data show that there is no apparent added value of considering entire 3'UTR HLA-G haplotypes for risk prediction after allogeneic HSCT for beta-thalassemia.

The Effect of KIRs Expression Profile in Donor/Recipient Pairs in HLA-Identical Sibling Hematopoietic Stem Cell Transplantation,

Abstract 4017 Objective:We investigated the distribution characteristics of KIRs expression profile in donor/recipient pairs with acute leukemia (AL) receiving HLA-identical sibling hematopoietic stem cell transplantation (sib-HSCT). We further explored the effect of KIRs expression profile in donor/recipient pairs on clinical outcome, including dynamics of donor T cell and NK cell engraftment. Methods:The genotypes of donor/recipient KIRs were determinated by polymerase chain reaction- sequence specific primer (PCR-SSP) for 80 pairs of donor/recipient receiving HLA-identical sibling hematopoietic stem cell transplantation. The multiple short tandem repeat (STR) PCR was used to evaluate the status of engraftment of donor T cells and NK cells at +14 days, 21 days, 28 days, 60 days and 90 days after transplantation in 24 cases. Results: 1.In 80 pairs of donor/recipient: (i) the KIRs were completely identical in 57.5% of donor/recipient pairs; (ii) the donors' KIRs contained the recipients' in 13.75% pairs; (iii) the recipients' KIRs contained the donors' in 17.5% of pairs; (iv) the KIRs were completely different in 11.25% pairs. The graft versus host (GVH) direction KIR-matched group was 75%. The percentage of group donor B/X and group donor A/A was 50%, respectively. 2. Comparing the patients from GVH direction KIR-matched and mismatched group, the incidence of acute (a) GVHD was 60% and 30%, respectively (P =0.0222), and 2-year OS was 62.96% and 94.12%, respectively (P =0.0492). Particularly, grade III-IV aGVHD rate of KIR-matched group was higher than that of non-KIR matched group(15% vs 0%). 3. Donor B/X group had a higher 2-year OS and 2-year relapse-free survival (RFS) compared with donor A/A group (89.23% vs 49.57%, P =0.0159, and 90% vs 59.71%, P =0.0239, respectively). Patients with three or less aKIRs had a lower 2-year OS (58.9% vs 92.44%, P =0.0338) and a lower RFS (65.14% vs 92.59%, P =0.0398), compared with patients with more aKIR. 4. Sequential monitoring of chimerism status of donor NK-cells in 24 cases revealed that on day+14, the percentage of full donor NK cells chimerism was higher in non-KIR matched patients than that of KIR matched patients (85.7% vs 52.9%, P =0.0456). Conclusions:Donor KIR genotype appears to have a direct impact on aGVHD, OS and RFS. Therefore, donor KIR genotype should be evaluated as an outcome predictor of the HLA-identical sib-HSCT. Disclosures:No relevant conflicts of interest to declare.

Impact of the Distribution and the Effect of KIRs and Activating KIR on Outcome of HLA-identical Sibling Hematopoietic Stem Cell Transplantation

To investigate the distribution and the effect of killer cell immunoglobulin-like receptor (KIR) genes, as well as to explore the impact of different activating KIRs in HLA-identical sibling hematopoietic stem cell transplantation (HSCT).

Natural Killer Cell Killing of Acute Myelogenous Leukemia and Acute Lymphoblastic Leukemia Blasts by Killer Cell Immunoglobulin-Like Receptor–Negative Natural Killer Cells after NKG2A and LIR-1 Blockade

Although the study of natural killer (NK) cell alloreactivity has been dominated by studies of killer cell immunoglobulin-like receptors (KIRs), we hypothesized that NKG2A and LIR-1, present on 53% +/- 13% and 36% +/- 18% of normal NK cells, respectively, play roles in the NK cell killing of primary leukemia targets. KIR(-) cells, which compose nearly half of the circulating NK cell population, exhibit tolerance to primary leukemia targets, suggesting signaling through other inhibitory receptors. Both acute myelogenous leukemia and acute lymphoblastic leukemia targets were rendered susceptible to lysis by fresh resting KIR(-) NK cells when inhibitory receptor-major histocompatibility class I interactions were blocked by pan-HLA antibodies, demonstrating that these cells are functionally competent. Blockade of a single inhibitory receptor resulted in slightly increased killing, whereas combined LIR-1 and NKG2A blockade consistently resulted in increased NK cell cytotoxicity. Dual blockade of NKG2A and LIR-1 led to significant killing of targets by resting KIR(-) NK cells, demonstrating that this population is not hyporesponsive. Together these results suggest that alloreactivity of a significant fraction of KIR(-) NK cells is mediated by NKG2A and LIR-1. Thus strategies to interrupt NKG2A and LIR-1 in combination with anti-KIR blockade hold promise for exploiting NK cell therapy in acute leukemias.

Improved outcome of patients older than 30 years receiving HLA-identical sibling hematopoietic stem cell transplantation for severe acquired aplastic anemia using fludarabine-based conditioning: a comparison with conventional conditioning regimen

Older age is a limitation for HLA-identical sibling hematopoietic stem cell transplantation (HSCT) as first-line therapy for severe acquired idiopathic aplastic anemia (SAA). Fludarabine (Flu)-based conditioning might improve outcome in older patients. We analyzed retrospectively 30 patients older than 30 years receiving such reduced-intensity conditioning HSCT according to recommendations of the European Group for Blood and Marrow Transplantation (EBMT) and compared their outcome to a control group receiving the standard regimen (cyclophosphamide+/-antithymocyte globulin) over the same study period (1998-2007). Patients conditioned with Flu had a higher probability of overall survival than the control group (p=0.04) when adjusting for recipient's age. This might be related to a trend towards a reduced incidence of graft failure in patients receiving Flu (0% vs. 11%, p=0.09), while no difference was observed regarding graft-versus-host disease incidence. Flu-based conditioning regimen may reduce the negative impact of age in older patients with SAA receiving an HLA-identical sibling HSCT.

HLA-haploidentical blood and bone marrow transplantation with anti-thymocyte globulin: Long-term comparison with HLA-identical sibling transplantation

We present an update of our results regarding related HLA-haploidentical and HLA-identical sibling hematopoietic stem cell transplantation (HSCT) in patients with leukemia. We compared the outcomes of 107 patients with leukemia undergoing HLA-identical sibling ( n = 51) or related HLA-haploidentical ( n = 56) HSCT performed during the same time period. Patients received BU-CY/CY-TBI in HLA-identical sibling HSCT or TBI + Ara-C + CY + ATG/CCNU + Ara-C + Bu + CY + ATG in haploidentical HSCT as conditioning regimens, followed by unmanipulated marrow and/or peripheral blood (PB) transplantation. All patients achieved full engraftment. The cumulative incidence of grades II through IV acute graft-versus-host disease (aGvHD) in the matched and haploidentical cohorts was 13.7% and 26.8% ( P< 0.05), respectively. The risk of developing cGvHD was not different between HLA-matched and haploidentical patients ( P> 0.05). The two-year incidence of treatment-related mortality for matched and haploidentical patients was 7.8% and 12.5%, respectively, with P> 0.05, and the incidence of relapse was 17% and 22%, respectively, with P > 0.05. The two-year adjusted leukemia-free survival for matched versus haploidentical patients was 76% and 68%, respectively, with P > 0.05, and the overall survival for matched versus haploidentical patients was 80% and 70%, respectively, with P > 0.05. Multivariate analyses showed that only advanced disease stage and a diagnosis of acute leukemia were related to increased risk of relapse, treatment failure, and overall mortality. In summary, HSCT performed with related HLA-haploidentical donors is a feasible approach with acceptable outcomes.

CD3−cd(16+56)+ Cell Dose Is An Important Factor Determining Clinical Outcomes in Patients Undergoing Unmanipulated HLA-Identical Sibling Hematopoietic Stem Cell Transplantation

Background: It has been suggested that the dose of the cellular components in the graft may influence the outcome of transplantation, especially CD3 |CD(16+56)+ cell(NK cell) is believed to play an important role in improving the transplant outcome in terms of preventing graft-versus-host disease(GVHD) and graft rejection, and as a mediator of the graft-versus-leukemia(GVL) effect. The current study attempted to evaluate the role of CD3−CD(16+56)+ cell dose on the outcome of HLA-identical sibling hematopoietic stem cell transplantation.Methods: We retrospective analyzed the outcomes of 72 patients receiving HLA-identical sibling hematopoietic stem cell transplantation between July 2005 and May 2008 in the first Affiliated Hospital of Soochow University. Diagnoses of these patients included acute leukemia(AL)(n=34), chronic myeloid leukemia(CML) (n=29), aplastic anemia(AA) (n=4), malignant lymphoma (n=3) and multiple myeloma (n=2). The median follow-up time is 19 months (range 0.5–36 months) after transplantation. Transplanted doses of CD3 |CD(16+56)+ cell were analyze in relation to engraftment, GVHD, infectious events, relapse and survival.Result: The median dose of NK cell in bone marrow grafts from patients receiving G-CSF-mobilized was 0.91× 107/Kg. Therefore the group received a dose of CD3 |CD(16+56)+ cell above 0.91×107/Kg wass a higher group. There were no significant difference between two groups for neutrophil and platelet recovery. The incidence of II°-‡W°aGVHD in low group was much more than that of high group(41%VS 18.2%, P<0.05). and there was a significantly higher incidence of infection in patients receiving a lower dose of CD3 |CD(16+56)+ cell (46.1%VS 21.2%, P<0.05). However there was no significant association between CD3-CD(16+56)+ cell and either cGVHD or relapse.Conclusions: High dose of CD3−CD(16+56)+ cell may play an important role in improving the outcome of transplantation in terms of reducing aGVHD and infection.

Association of drug metabolism gene polymorphisms with toxicities, graft-versus-host disease and survival after HLA-identical sibling hematopoietic stem cell transplantation for patients with leukemia

Individual differences in drug efficacy or toxicity can be influenced by genetic factors. We investigated whether polymorphisms of pharmacogenes that interfere with metabolism of drugs used in conditioning regimen and graft-versus-host disease (GvHD) prophylaxis could be associated with outcomes after HLA-identical hematopoietic stem cell transplantation (HSCT). Pharmacogenes and their polymorphisms were studied in 107 donors and patients with leukemia receiving HSCT. Candidate genes were: P450 cytochrome family (CYP2B6), glutathione-S-transferase family (GST), multidrug-resistance gene, methylenetetrahydrofolate reductase (MTHFR) and vitamin D receptor (VDR). The end points studied were oral mucositis (OM), hemorrhagic cystitis (HC), toxicity and venoocclusive disease of the liver (VOD), GvHD, transplantation-related mortality (TRM) and survival. Multivariate analyses, using death as a competing event, were performed adjusting for clinical factors. Among other clinical and genetic factors, polymorphisms of CYP2B6 genes that interfere with cyclophosphamide metabolism were associated with OM (recipient CYP2B6(*)4; P=0.0067), HC (recipient CYP2B6(*)2; P=0.03) and VOD (donor CYP2B6(*)6; P=0.03). Recipient MTHFR polymorphisms (C677T) were associated with acute GvHD (P=0.03), and recipient VDR TaqI with TRM and overall survival (P=0.006 and P=0.04, respectively).Genetic factors that interfere with drug metabolisms are associated with treatment-related toxicities, GvHD and survival after HLA-identical HSCT in patients with leukemia and should be investigated prospectively.

The diversity of KIR gene in Chinese Northern Han population and the impact of donor KIR and patient HLA genotypes on outcome following HLA-identical sibling allogeneic hematopoietic stem cell transplantation for hematological malignancy in Chinese people

Killer cell immunoglobulin-like receptors (KIRs) are members of a group of molecules that specifically recognize HLA class I ligands and are found on subsets of human lymphopoetic cells. The number of KIR loci can vary between individuals, resulting in a heterogeneous array of possible KIR genes. The range of observed profiles has been explained by the occurrence of two haplotype families termed A and B, which can be distinguished on the basis of certain KIR sequences. Immunogenetic analysis of different ethnic populations shows significant differences in terms of the distribution for group A and group B haplotypes. Recently, attention has been focused on the role of killer cell immunoglobulin-like receptor (KIR)-ligand incompatibility in the graft-versus-host direction between donor and recipient in allogeneic hematopoietic stem-cell transplantation (ASCT). The goal of this study was to study the frequency of specific KIR genes in Chinese Northern Han population and evaluate the role of KIR-ligand mismatch in Chinese HLA-identical sibling hematopoietic stem cell transplantation patients with hematological malignancy. Here genomic DNA from 150 Northern Chinese Han individuals was typed for the presence or absence of KIR genes. Seventy-four allogeneic stem cell transplantation donor/recipient pairs were typed for HLA-A, B, C and KIR. Sixteen KIR genes were observed in the population, and framework genes 3DL3, 3DP1, 2DL4, and 3DL2 were present in all individuals. Twenty-two different genotypes were found. Group A haplotypes outnumbered group B haplotypes in frequency by approximately 3:1, with individuals having two group A haplotypes accounting for 51.9% (78/150). We observed that 57 out of 74 (77.3%) donor-recipient pairs could be characterized by lack of recipient HLA ligand for donor KIR. We observed that 36 out of 45 (80%) donor-recipient HLA-identical sibling transplant pairs could be characterized by lack of recipient HLA ligand for donor KIR. Cumulative incidence analysis of aGVHD in patients undergoing HLA-identical sibling hematopoietic stem cell transplantation in this study demonstrated a decreased incidence of severe aGVHD in patients lacking HLA ligand for donor-inhibitory KIR2DL1 (31.4 vs. 70%, P = 0.029). And also in AML (acute myeloid leukemia) patients lacking HLA ligand for donor-inhibitory KIR and KIR2DL1 (17.6 vs. 75%, P = 0.03). Our data demonstrated that the Chinese Han population is distinct in KIR gene frequencies and putative KIR haplotypes in comparison to some other populations. Almost all allogeneic donors could be characterized as having an inhibitory KIR for each of the three known class I ligands. KIR and KIR2DL1 mismatch is associated with lower aGVHD in Chinese after HLA-identical sibling hematopoietic stem cell transplantation.

Distribution of immunoglobulin like receptor gene in Han population in China and the impact thereof on the HLA-identical sibling hematopoietic stem cell transplantation

To investigate the distribution of killer immunoglobulin like receptor (KIR) gene in the Han population in north China and the impact of donor KIR and patient HLA genotypes on the outcome of HLA-identical sibling hematopoietic stem cell transplantation patients with hematological malignancy. Polymerase chain reaction with sequence-specific primers (PCR-SSP) was used to detect the KIR distribution of 150 healthy people and the KIR genotype of donor and HLA genotype of allogeneic stem cell transplantation recipients of 74 donor-recipient pairs, and a retrospective study was carried out to analyze the outcomes of 45 patients with various hematological malignancies who received non T-cell-depleted transplant from HLA-identical sibling donors, all the subjects being of Han nationality in north China. The gene frequencies of KIR2DL1, KIR2DL2, KIR2DL3, and KIR3DL1 were 100%, 20%, 100%, and 95% respectively. 96% of the allogeneic donors carried one of the 3 class I ligands of inhibitory KIR. 36 of the 45 (80%) donor-recipient HLA-identical sibling transplant pairs lacked recipient HLA ligand for donor KIR, among which 35 lacked recipient HLA ligand for donor KIR2DL1, 1 pair lacked that for KIR2DL2/2DL3, and 31 pairs lacked that for KIR3DL1. Cumulative incidence analysis of graft versus host disease (GVHD) in the patients undergoing HLA-identical sibling hematopoietic stem cell transplantation demonstrated that the incidence of severe acute GVHD (aGVHD) in the patients lacking HLA ligand for donor-inhibitory KIR2DL1 was 31%, significantly lower than that of the patients with HLA ligand for donor-inhibitory KIR2DL1 (70%, P = 0.029), and the incidence of severe aGVHD in the acute myeloid leukemia patients lacking HLA ligand for donor-inhibitory KIR and KIR2DL1 was 18%, significantly lower than that of the KIR compatible patients (75%, P = 0.03). Almost all Chinese of Han nationality in north China carry having one of the 3 known class I ligands of inhibitory KIR. KIR and KIR2DL1 mismatch is associated with lower aGVHD after HLA-identical sibling hematopoietic stem cell transplantation.

Prognostic significance of NOD2/CARD15 variants in HLA-identical sibling hematopoietic stem cell transplantation: effect on long-term outcome is confirmed in 2 independent cohorts and may be modulated by the type of gastrointestinal decontamination

To assess the role of NOD2/CARD15 variants on the long-term outcome of allogeneic stem cell transplantation in a genetically homogeneous group, we extended our previous study (cohort I, n = 78) and typed DNA for NOD2/CARD15 single nucleotide polymorphisms (SNPs) from an additional 225 recipients and their HLA-identical sibling donors (cohort II) treated at four other European centers. Results of genotyping were compared with clinical outcome. The strong association of NOD2/CARD15 variants with transplantation-related mortality (TRM) was confirmed in univariate and multivariate analysis; TRM increased from 20% in cohort I/22% in cohort II in recipient/donor pairs without any NOD2/CARD15 variants to 47% in cohort I/32% in cohort II in the presence of one variant in either donor or recipient and further to 57% in cohort I/74% in cohort II in the presence of 2 or more variants (P < .002 in both cohorts). NOD2/CARD15 SNPs were not associated with relapse rate but had a strong impact on overall survival. In an analysis of center effects, the type of gastrointestinal decontamination was the only factor interfering with the prognostic significance of NOD2/CARD15 SNPs. Our data further support an interaction between gastrointestinal defense mechanisms, activation of the innate immune system, and specific transplant-related complications.

682. Collection and Genetic Correction of Fanconi Complement Type A Hematopoietic Stem Cells: Results of Two Pilot Studies

Fanconi anemia (FA) is a genetic syndrome characterized by the uniform development of aplastic anemia. Current therapy for patients lacking HLA-identical sibling hematopoietic stem cell (HSC) donors are not optimal. We have opened two phase I clinical trials to determine if potentially useful numbers of CD34+ cells can be collected early in the course of the disease (collection study) and if these cells, once corrected, can engraft without cytoreduction and demonstrate proliferative advantage in vivo over un-corrected cells (gene transfer study). To date, 7 FA patients have undergone a 20 ml/kg bone marrow harvest (BMH) with an average of 1.9|[times]|106 CD34+ cells/kg (range 0.3|[ndash]|2.9|[times]|106 CD34+ cells/kg) collected, suggesting that collection of adequate numbers of cells is possible but challenging, even early in the disease. In the gene transfer study, 3 FA patients with genotype A (FAA) have enrolled, meeting eligibility criteria of FAA, no evidence of malignancy and a minimum of 1|[times]|105 viable CD34+ cells/kg for ex vivo culture and gene transfer. BMHs from the 3 patients (2 fresh and one previously cryopreserved) were CD34+ cell selected. Despite collection before significant pancytopenia, an average of only 5|[times]|105 CD34+ cells/kg (range 1.5|[ndash]|10|[times]|105 CD34+ cells/kg) was purified from these 3 cases representing |[sim]|10% of the expected yield from normal individuals. These cells underwent ex vivo gene transfer using cytokine prestimulation in serum-free medium followed 2 exposures to a GALV-MSCV-FANCA vector. Transduction efficiency of the final product determined by real-time PCR analysis of progenitors averaged 48% (range 40|[ndash]|62%). Equivalent correction of mitomycin C hypersensitivity in progenitor cells confirmed this analysis at the functional level. Nucleated cell recovery after ex vivo manipulation was 82|[ndash]|110% of input nucleated cells using freshly harvested bone marrow derived CD34+ cells (N=2). However, despite good CD34+ cell recovery and viability after CD34+ selection, only 6% of input nucleated cells were recovered utilizing CD34+ cells purified from the previously cryopreserved bone marrow and these cells were not re-infused. In the two patients who did receive gene corrected cells, the total cell dose re-infused was 2.5|[ndash]|3.5|[times]|105 nucleated cells/kg, reflecting the low number of initial CD34+ cells placed in culture. FAA vector sequences were detected in the PB of one patient early post-infusion (+4 weeks) but none was detected after 8 weeks. Despite no long term detection of the corrective gene in the PB and BM, both patients exhibited a transient but marked improvement (10|[ndash]|20% increase) in their peripheral blood hemoglobin (> 6 months) and platelets counts (2|[ndash]|3 months). The data demonstrates that gene transfer efficiency in the clinical setting has been significantly improved, however the collection of adequate numbers of HSC may be the critical barrier to the success of genetic correction attempts in FA.

Differences in Characteristics of US Hematopoietic Stem Cell Transplantation Centers by Proportion of Racial or Ethnic Minorities

Racial or ethnic minorities with leukemia who receive HLA-identical sibling hematopoietic stem cell transplants (HSCTs) are reported to have worse survival when compared with whites. Characteristics of US HSCT centers according to the proportion of ethnic minorities who undergo transplantation were compared to explore systematic differences among centers; the association with 100-day mortality was evaluated to determine whether center factors may explain the observed discrepant survival among ethnic minorities. One hundred sixteen US transplantation centers that performed HLA-identical sibling transplantations for leukemia were analyzed. We compared physician and health care provider staffing, transplantation unit procedure and resources, and medical center organization according to the volume procedure ratio of ethnic minorities who underwent transplantation and also according to the ratio of Hispanics who underwent transplantation. Centers that performed transplantation in a higher proportion of ethnic minorities were more likely to perform fewer transplantations per year, to have fewer devoted transplant beds, to be in an urban setting, to have a lower physician to patient volume ratio, and to follow up survivors 1 year after transplantation. Centers that performed transplantation in a higher proportion of Hispanics were more likely to perform fewer transplantations per year and to have fewer devoted transplantation beds, were less likely to perform outpatient transplantations, were more likely to be in an urban setting, and were less likely to have posttransplantation immunization protocols. Observed differences in center factors were not associated with 100-day mortality after adjustment for disease severity. Our results suggest that the inferior survival reported in ethnic minorities after HSCT may not be readily explained by center effects.

Comparison of HLA-Identical Sibling Hematopoietic Stem Cell Transplant (HCT) Versus Chemotherapy as Postremission Therapy in t(8;21) Acute Myeloid Leukemia (AML).

The t(8;21) is associated with high complete remission (CR) rates and high survival rates after cytarabine-containing postremission therapy for AML. However, patients with leukocytosis and additional cytogenetic abnormalities, such as loss of sex chromosome (LOS), have worse outcomes. We compared patients ages 16 to 60 years with t(8;21) AML in first CR, comparing 132 patients receiving postremission chemotherapy (chemo) with 118 receiving HLA-identical sibling HCT. The chemo cohort included patients treated with double induction followed by cytarabine-containing regimens in one of eight different German AML Intergroup clinical trials (SHG-Hannover-AML-2/95, SHG-Hannover-AML-1/99, SHG-Dresden-AML-96, AMLHD93, AMLHD98A, AMLCG92, AMLCG99, OSHO-AML-96) between 1993 and 2002. HCT recipients were registered with the CIBMTR from 1990 to 2000. To adjust for potential bias caused by delayed entry in the transplant cohort, left-truncated univariate analysis and Cox multivariate models were used. The median age of patients undergoing chemo and HCT were 42 and 32 years of age, respectively (p<0.001). The table below shows five-year outcomes in months, including relapse rate, treatment related mortality (TRM), adjusted leukemia free survival (LFS) and adjusted overall survival (OS) according to multivariate analysis (Table). WBC > 25.4×109/L was associated with higher relapse risk (RR=2.09, P=0.03), shorter LFS (RR=1.9, P=0.008) and shorter survival (RR=1.91, P=0.012), independent of postremission treatment. Neither year of treatment nor specific chemotherapy protocols were significantly associated with outcomes. HCT and chemotherapy had similar overall survival in patients with LOS and leukocytosis; in those without LOS, survival was significantly higher with chemotherapy. In this cohort of patients with t(8;21) treated in the 1990s, high transplant related mortality offset the antileukemia benefit of HCT, suggesting that HCT be reserved for patients who fail postremission chemotherapy.TRM (95% CI)Relapse (95% CI)LFS (95% CI)OS (95% CI)LOSNo LOSChemo6 (2–11)29 (21–37)64 (55–73)55 (41–69)84 (74–92)HCT32 (22–44)14 (8–21)55 (45–65)64 (50–77)53 (39–67)P-value*< 0.0010.010.240.740.002*From multivariate models

Early Results of the Clinical Collection and Genetic Correction of Fanconi Complement Type A Hematopoietic Stem Cells.

Fanconi anemia (FA) is a genetic syndrome characterized by almost uniform development of aplastic anemia. Current therapies for patients lacking HLA-identical sibling hematopoietic stem cell (HSC) donors have shown high morbidity and mortality in clinical trials. Genetic correction of FA HSC using viral vectors has been demonstrated in animal models. However, harvesting of sufficient CD34+ cells at the time that HSC therapy is clinically indicated is difficult due to the severe bone marrow hypoplasia that accompanies pancytopenia. We have opened two phase I clinical trials that seek to determine if potentially useful numbers of CD34+ cells can be collected early in the course of the disease (collection study) and if these cells, once corrected, can engraft without cytoreduction and demonstrate proliferative advantage in vivo over un-corrected cells (gene transfer study). These studies are being conducted with approval by the FDA/NIH-RAC/Institutional IRB and monitored by an independent DSMB. To date, 4 FA patients have undergone a 20 ml/kg bone marrow harvest (BMH) with an average of 1.3x106 CD34+ cells/kg (range 0.3–2.9x106 CD34+ cells/kg) collected, suggesting that collection of adequate numbers of cells will be challenging, even early in the disease. In the gene transfer study, 3 FA patients with genotype A (FAA) have enrolled, meeting eligibility criteria of FAA, no evidence of malignancy and a minimum of 1x105 viable CD34+ cells/kg for ex vivo culture and gene transfer. BMHs from the 3 patients (2 fresh and one previously cryopreserved) were CD34+ cell selected using the CliniMACS device. Despite collection before significant pancytopenia, an average of only 5x105 CD34+ cells/kg (range 1.5–10x105 CD34+ cells/kg) was purified from these 3 cases representing ~10% of the expected yield from normal individuals. These cells underwent ex vivo gene transfer using cytokine prestimulation in serum-free medium followed 2 exposures to a GALV-MSCV-FANCA vector. Transduction efficiency of the final products determined by real-time PCR analysis of CD34+-derived progenitors averaged 48% (range 40–62%). Equivalent efficiency of correction of mitomycin C hypersensitivity in progenitor cells confirmed this analysis at the functional level. Nucleated cell recovery after ex vivo manipulation was 82–110% of input nucleated cells using freshly harvested bone marrow derived CD34+ cells (N=2). However, despite good CD34+ cell recovery and viability after CD34+ selection, only 6% of input nucleated cells were recovered utilizing CD34+ cells purified from the previously cryopreserved bone marrow and these cells were not re-infused. In the two patients who did receive gene corrected cells, the total cell dose re-infused was 2.5–3.5x105 nucleated cells/kg, reflecting the low number of initial CD34+ cells placed in culture. One patient is now 6 months post re-infusion with no evidence of gene marking observed in her PB or BM. The second patient had detectable FAA vector sequences in her PB early post-infusion (+4 weeks) but had none detected +8 weeks. The data suggest that while gene transfer efficiency in the clinical setting has been significantly improved, collection and expansion (either in vitro or in vivo) of adequate number of HSC may be critical to the success of genetic correction attempts in FA.