Genome-wide single-nucleotide polymorphism analysis revealed SUFU suppression of acute graft-versus-host disease through downregulation of HLA-DR expression in recipient dendritic cells.

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). To identify recipient risk factors, a genome-wide study was performed including 481,820 single-nucleotide polymorphisms (SNPs). Two GVHD susceptibility loci (rs17114803 and rs17114808) within the SUFU gene were identified in the discovery cohort (p = 2.85 × 10(-5)). The incidence of acute GVHD among patients homozygous for CC at SUFU rs17114808 was 69%, which was significantly higher than the 8% rate observed in CT heterozygous patients (p = 0.0002). In an independent validation cohort of 100 patients, 50% of the patients with the CC genotype developed GVHD compared to 8% of the patients with either CT or TT genotype (p = 0.01). In comparison to CC dendritic cells, those from CT expressed higher levels of SUFU mRNA and protein, had lower levels of surface HLA-DR, and induced less allogeneic mixed leukocyte response (MLR). Ectopic expression of SUFU in THP-1 derived DCs reduced HLA-DR expression and suppressed MLR, whereas silencing of SUFU enhanced HLA-DR expression and increased MLR. Thus our findings provide novel evidence that recipient SUFU germline polymorphism is associated with acute GVHD and is a novel molecular target for GVHD prevention and treatment.

Natural killer cell therapy in children with relapsed leukemia.

BACKGROUND: Novel therapies are needed for children with relapsed or refractory leukemia. We therefore tested the safety and feasibility of haploidentical natural killer cell therapy in this patient population. PROCEDURE: Twenty-nine children who had relapsed or refractory leukemia were treated with chemotherapy followed by the infusion of haploidentical NK cells. Cohort 1 included 14 children who had not undergone prior allogeneic hematopoietic cell transplantation (HCT), whereas Cohort 2 included 15 children with leukemia that had relapsed after HCT. RESULTS: Twenty-six (90%) NK donors were KIR mismatched (14 with one KIR and 12 with 2 KIRs). The peak NK chimerism levels were >10% donor in 87% of the evaluable recipients. In Cohort 1, 10 had responsive disease and 12 proceeded to HCT thereafter. Currently, 5 (36%) are alive without leukemia. In Cohort 2, 10 had responsive disease after NK therapy and successfully proceeded to second HCT. At present, 4 (27%) are alive and leukemia-free. The NK cell infusions and the IL-2 injections were well-tolerated. CONCLUSIONS: NK cell therapy is safe, feasible, and should be further investigated in patients with chemotherapy-resistant leukemia.

Effect of donor KIR2DL1 allelic polymorphism on the outcome of pediatric allogeneic hematopoietic stem-cell transplantation.

PURPOSE: Killer-cell immunoglobulin-like receptors (KIRs) that regulate natural-killer cells are highly polymorphic. Some KIR2DL1 alleles encode receptors that have stronger signaling function than others. We tested the hypothesis that the clinical outcomes of allogeneic hematopoietic stem-cell transplantation (HSCT) could be affected by donor KIR2DL1 polymorphism. PATIENTS AND METHODS: All 313 pediatric patients received allogeneic HSCT at a single institution. Donor KIR2DL1 functional allele typing was retrospectively performed using single nucleotide polymorphism assay. RESULTS: Patients who received a donor graft containing the functionally stronger KIR2DL1 allele with arginine at amino acid position 245 (KIR2DL1-R(245)) had better survival (P = .0004) and lower cumulative incidence of disease progression (P = .001) than those patients who received a donor graft that contained only the functionally weaker KIR2DL1 allele with cysteine at the same position (KIR2DL1-C(245)). The effect of KIR2DL1 allelic polymorphism was similar in patients with acute myeloid leukemia or acute lymphoblastic leukemia among all allele groups (P ≥ .71). Patients who received a KIR2DL1-R(245)-positive graft with HLA-C receptor-ligand mismatch had the best survival (P = .00003) and lowest risk of leukemia progression (P = .0005) compared with those who received a KIR2DL1-C(245) homozygous graft. CONCLUSION: Donor KIR2DL1 allelic polymorphism affects recipient outcomes after allogeneic HSCT. These findings have substantial implications for prognostication and donor selection.

Detectable minimal residual disease before hematopoietic cell transplantation is prognostic but does not preclude cure for children with very-high-risk leukemia.

In patients with acute leukemia, detection of minimal residual disease (MRD) before allogeneic hematopoietic cell transplantation (HCT) correlates with risk of relapse. However, the level of MRD that is most likely to preclude cure by HCT is unclear, and the benefit of further chemotherapy to reduce MRD before HCT is unknown. In 122 children with very-high-risk acute lymphoblastic leukemia (ALL; n = 64) or acute myeloid leukemia (AML, n = 58), higher MRD levels at the time of HCT predicted a poorer survival after HCT (P = .0019); MRD was an independent prognostic factor in a multivariate analysis (P = .0035). However, the increase in risk of death associated with a similar increment of MRD was greater in ALL than in AML, suggesting that a pretransplantation reduction of leukemia burden would have a higher impact in ALL. At any given MRD level, survival rates were higher for patients treated in recent protocols: the 5-year overall survival for patients with ALL was 49% if MRD was detectable and 88% if it was not and the corresponding rates for patients with AML were 67% and 80%, respectively. Although MRD before HCT is a strong prognostic factor, its impact has diminished and should not be regarded as a contraindication for HCT.

Prediction of CD34(+) cell yield in hematopoietic cell products from children by peripheral blood CD34(+) cell counts.

BACKGROUND AIMS: Peripheral blood stem cells (PBSC) are increasingly used as an alternative to bone marrow in autologous transplantations. In adult patients, the peripheral blood CD34(+) cell count is a good predictor of CD34(+) cell yield in apheresis. However, the determinants of stem cell yield in the pediatric population have not been well established. METHODS: We retrospectively studied 396 apheresis procedures in 301 pediatric patients. Receiver operating characteristic (ROC) curves based on pre-apheresis peripheral blood CD34(+) cell counts were generated to facilitate prediction of the optimal timing of PBSC collection. The associations between CD34(+) cell yield and age and mobilization regimen were analyzed. RESULTS: Significant differences in CD34(+) cell yield among different age groups were observed. Furthermore, higher CD34(+) cell yields were obtained in patients receiving chemotherapy as part of the mobilization regimen than those without chemotherapy. A correlation was noted between the CD34(+) cell yield and blood surrogate markers, including white blood cell count, absolute neutrophil count and pre-apheresis peripheral blood CD34(+) cell count. Cut-off values of > 35 CD34(+) cells/µL in patients < 15 years old and > 45 CD34(+) cells/µL in patients ≥ 15 years old were strong predictors of an adequate PBSC collection in one apheresis session. For clinical use, ROC curves and tables were generated to assist advance planning for PBSC collection. CONCLUSIONS: The pre-apheresis peripheral blood CD34(+) cell count is most useful in predicting PBSC yield. Our new cut-off values have better operating characteristics for children than the conventional value of 20 CD34(+) cells/µL used for adults.

High success rate of hematopoietic cell transplantation regardless of donor source in children with very high-risk leukemia.

We evaluated 190 children with very high-risk leukemia, who underwent allogeneic hematopoietic cell transplantation in 2 sequential treatment eras, to determine whether those treated with contemporary protocols had a high risk of relapse or toxic death, and whether non-HLA-identical transplantations yielded poor outcomes. For the recent cohorts, the 5-year overall survival rates were 65% for the 37 patients with acute lymphoblastic leukemia and 74% for the 46 with acute myeloid leukemia; these rates compared favorably with those of earlier cohorts (28%, n = 57; and 34%, n = 50, respectively). Improvement in the recent cohorts was observed regardless of donor type (sibling, 70% vs 24%; unrelated, 61% vs 37%; and haploidentical, 88% vs 19%), attributable to less infection (hazard ratio [HR] = 0.12; P = .005), regimen-related toxicity (HR = 0.25; P = .002), and leukemia-related death (HR = 0.40; P = .01). Survival probability was dependent on leukemia status (first remission vs more advanced disease; HR = 0.63; P = .03) or minimal residual disease (positive vs negative; HR = 2.10; P = .01) at the time of transplantation. We concluded that transplantation has improved over time and should be considered for all children with very high-risk leukemia, regardless of matched donor availability.

Blood dendritic cells suppress NK cell function and increase the risk of leukemia relapse after hematopoietic cell transplantation.

NK cells play an important role in hematopoietic stem cell transplantation (HCT) and in cross talk with dendritic cells (DCs) to induce primary T cell response against infection. Therefore, we hypothesized that blood DCs should augment NK cell function and reduce the risk of leukemia relapse after HCT. To test this hypothesis, we conducted laboratory and clinical studies in parallel. We found that although, phenotypically, NK cells could induce DC maturation and DCs could in turn increase activating marker expression on NK cells, paradoxically, both BDCA1(+) myeloid DCs and BDCA4(+) plasmacytoid DCs suppressed the function of NK cells. Patients who received an HLA-haploidentical graft containing a larger number of BDCA1(+) DCs or BDCA4(+) DCs had a higher risk of leukemia relapse and poorer survival. Further experiments indicated that the potent inhibition on NK cell cytokine production and cytotoxicity was mediated in part through the secretion of IL-10 by BDCA1(+) DCs and IL-6 by BDCA4(+) DCs. These results have significant implications for future HCT strategies.

Iron overload in survivors of childhood leukemia after allogeneic hematopoietic stem cell transplantation.

Iron overload has not been studied extensively and prospectively in pediatric survivors of allogeneic hematopoietic stem cell transplantation (HSCT); therefore, we conducted a prospective long-term study of 133 survivors of childhood leukemia to assess the incidence of and risk factors for iron overload and to investigate its association with organ dysfunction. One yr after HSCT, the mean serum ferritin level was 1158 ng/mL (range, 22-3264 ng/mL), with 124 patients (93.2%) having a serum ferritin level that exceeded the upper limit of the normal range (110 ng/mL). Thereafter, the serum ferritin level declined over time. There was a positive correlation between the level of serum ferritin and that of total bilirubin (r = 0.21, p < 0.001) and glutamate pyruvate transaminase (r = 0.17, p < 0.001). A high concentration of serum ferritin was associated with low cardiac fractional shortening (r = -0.15, p = 0.047). In addition, patients with hypothyroidism and GH deficiency had a higher level of serum ferritin than those without (p < 0.02). We conclude that iron overload is common after HSCT and is associated with hepatic, cardiac, and endocrine dysfunction.

A prospective cohort study of late sequelae of pediatric allogeneic hematopoietic stem cell transplantation.

As survivors of pediatric allogeneic hematopoietic stem cell transplantations (HSCTs) increase in number, it is increasingly important to evaluate their well-being. We conducted this prospective cohort study to evaluate the cumulative incidence and risk factors for late sequelae of HSCT. Comprehensive surveillance tests were performed annually on every participant, regardless of signs and symptoms, to obtain accurate information on the time-of-onset of each late event to allow hazard function analyses. All participants included in this report had been followed for at least 3 years after HSCT. With a median follow-up of 9 years and a current age of 18.5 years, only 20 of the 155 participants (13%) had no late sequelae; 18 survivors (12%) had 1 chronic health condition, 71 (46%) had 2-4 conditions, and 46 (30%) had 5-9 conditions. Risk factors for increasing number of chronic conditions included young age at the time of HSCT, female sex, high radiation dose, and history of chronic graft-versus-host disease. The cumulative incidence at 10 years for common late events was as follows (ordered by the median time-of-onset): osteonecrosis 13.8%, chronic renal insufficiency 26.8%, hypothyroidism 45.1%, growth hormone deficiency 31.2%, female hypogonadism 57.4%, osteopenia 47.7%, cataracts 43.4%, pulmonary dysfunction 63.2%, and male hypogonadism 20.3%. Coexistence of multiple late sequelae was common in HSCT survivors. Our findings provide a basis for more effective patient counseling, optimal surveillance, and early intervention.