HLA-haploidentical Hematopoietic Stem Cell Research Articles

Recovery Of Gamma/Delta+ T Cells After Transplantation With Alpha-Beta+/CD19+ Lymphocyte Depleted Hematopoietic Stem Cells From HLA-Haploidentical Donors

HLA-haploidentical hematopoietic stem cell transplantation (HSCT) using CD34+ selected cells is a widely used procedure, which, however, is complicated by delayed immune reconstitution. We recently developed a new method of graft manipulation based on the physical removal of αβ+ T cells and CD19+ B cells, which permits to leave mature natural killer (NK) cells and γδ+ T cells in the graft. These cells can exert a graft-versus-leukemia (GvL) effect and reduce the risk of infection. In particular, unconventional γδ T cells play a critical role in both innate and adaptive immunity and exert HLA-unrestricted cytotoxicity against both solid and hematological tumors, thus potentially acting as beneficial effector cells in transplanted patients. Moreover, such grafts may limit the risk of graft-versus-host disease and prevent EBV-related lymphoproliferative disease.We performed phenotypic and functional studies on γδ T cells collected from 20 pediatric patients (pts, 13 males, 7 females, median age 10 years, range 6 months to 16 years) that received this type of allograft. Eighteen pts had acute leukemia and 2 non-malignant disorders. Ex vivo assays of peripheral blood γδ T cell phenotype and function were performed weekly until Hospital discharge and monthly until 6 months after HSCT. Phenotype of γδ T cells was analysed by flow cytometry. Analyses were performed on mononuclear cells labelled with mAb panels (CD3, CD45, pan-γδ, anti-Vδ1, -Vδ2, -Vγ9, CD45RO, CD45RA, CD27, CD16, CD56) allowing the identification of the main γδ+ T cell subsets, including Vδ1+ and Vδ2+ cells, naïve, central memory (CM), effector memory (EM) and terminally differentiated (TD) γδ T cells.Functional studies were performed using γδ T cells shortly after collection from pts, as well as after in vitro expansion with zoledronic acid and IL-2 for 10 days. Cytotoxic activity of γδ T cells was tested against primary leukemia cells, through CD107a degranulation assay and/or standard 51Cr-release assay.In the first 4 weeks after HSCT, T cells were consistently of the γδ subset (>90% of CD45+CD3+ cells); by contrast, αβ+ T cells gradually increased over time. In approximately half of the pts, the percentage of αβ T cells exceeded that of γδ T cells already starting from 30 days after HSCT. γδ T cells consisted of Vδ2+Vγ9+ and Vδ1+Vγ9+/- cells, and marginally of the Vδ1-Vδ2-Vγ9- population. Detailed phenotypic characterization of Vδ1+ and Vδ2+ γδ T cells revealed that, at day +20 after HSCT, 44% of Vδ1+ cells were CM (identified as CD45RO+CD27+ cells), 26% naïve (CD45RO-CD27+), 21.4% TD (CD45RO-CD27-) and 6.1% EM (CD45RO+CD27-). Similarly, 55.4% of Vδ2+ γδ T lymphocytes were CM, 9.8% naïve, 11.4% TD and 23.1% EM. The proportion of the different Vδ2+ γδ T cell subset did not change significantly over time, especially when comparing that present at day +20 after HSCT (time point, TP1) with that measured 30 days after the attainment of a 1:1 ratio of αβ-to- γδ T cells (TP2) (Figure 1, left panel). By contrast, by comparing TP1 and TP2, we found that Vδ1+ CM γδ T cells decreased and EM cells increased over time, while naïve or TD Vδ1+ γδ T cells did not change (Figure 1, right panel). In transplanted pts experiencing cytomegalovirus (CMV) reactivation, γδ T cells mostly consisted of Vδ1+ cells (mean 59.8% of γδ T cells), among which 49% were TD, 22.7% EM, 18.9% CM and 10.1% naïve. Noteworthy, in transplanted pts who did not have CMV reactivation, the main γδ T cells showed a Vδ2+ phenotype.Functional studies revealed that pt-derived γδ T cells consistently expanded in vitro after exposure to zoledronic acid and IL-2, the resulting Vγ9Vδ2 population expressing mainly an EM phenotype. These Vγ9Vδ2 cells exerted cytotoxic activities against primary allogeneic leukemia cells, especially when leukemia cells were pre-treated with zoledronic acid (Figure 2). More importantly, both Vδ1+ and Vδ2+ γδ T cells obtained from transplanted pts showed cytotoxic activity against primary leukemia cells, as assessed by CD107a degranulation assay.In conclusion, we provide the first phenotypic and functional characterization of γδ T cells, analyzed over time in children transplanted with grafts depleted of αβ+ T cells and of B lymphocytes. Our results support the concept that γδ T cells are important effector cells, which can be expanded and activated after exposure to bisphosphonates and IL-2 with the aim of improving their killing capacity against leukemia cells. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Removal Of Alpha/Beta+ T Cells and Of CD19+ B Cells From The Graft Translates Into Rapid Engraftment, Absence Of Visceral Graft-Versus-Host Disease and Low Transplant-Related Mortality In Children With Acute Leukemia Given HLA-Haploidentical Hematopoietic Stem Cell Transplantation

T-cell depleted HLA-haploidentical hematopoietic stem cell transplantation (HSCT) is a suitable option for patients in need of an allograft who lack a HLA-matched donor. Although it offers the advantage of being immediately applicable to virtually all patients, so far, graft manipulation with removal of all T lymphocyte subsets and of natural killer (NK) cells has been associated with an increased risk of life-threatening infections, as well as, in some studies, of leukemia recurrence.We recently developed a new method of graft manipulation based on the physical removal of αβ+ T cells and CD19+ B cells, which permits to leave mature NK cells and γδ+ T cells in the graft. We, thus, started a formal study (NCT01810120) in children with acute leukemia aimed at evaluating the safety and efficacy of this approach. As of April 2013, we enrolled 45 patients (pts; 29 males, 16 females). Median age at HSCT was 10.1 years (range 0.9-17.9). Thirty-five pts had acute lymphoblastic leukemia (ALL) and 10 acute myeloid leukemia (AML); all children were transplanted in morphological complete remission (CR). Fifteen pts were transplanted in first CR, 27 in second CR and 3 in more advanced CR. All pts transplanted in CR1 had either poor cytogenetic/molecular characteristics or high levels of minimal residual disease (MRD) at the end of induction therapy. The donor was either the mother (n=25) or the father (n=20); according to the model of KIR/KIR ligand disparity, 22 pts were transplanted from an NK-alloreactive donor. The median number of CD34+ cells, NK cells, γδ+ T cells, B cells and αβ+ T cells were 14.6, 31.7, 7.8, 0.08 and 0.04x106/kg, respectively. A myeloablative regimen, containing Total Body Irradiation in 34 cases, was given to all children, who also received anti-thymocyte globulin (12 mg/kg over 3 days, from -5 to -3). Rituximab (200 mg/m2) was administered on day -1 to further prevent EBV-related lymphoproliferative disorders. No pharmacological graft-versus-host disease (GVHD) prophylaxis was employed after transplantation.Sustained primary engraftment occurred in 44/45 pts, the remaining child being successfully re-transplanted from the other parent. The median time to reach an absolute neutrophil count >0.5x109/L and a platelet count >50x109/L was 13 days (9-18) and 11 days (8-20). No child developed gut or liver acute GVHD. Thirteen pts experienced skin-only grade I-II GVHD, this leading to a cumulative incidence (CI) of 29% (95% confidence interval, CO. IN., 18-45). Only 2 pts developed skin limited chronic GVHD. Two pts died for causes other than disease relapse (both in the first 60 days after HSCT), the CI of transplantation-related mortality (TRM) being 4% (CO. IN. 1-16). Seven pts relapsed, the CI of disease recurrence being 16% (CO. IN. 6-32). With a median follow-up of 11 months (range 2-30), the 2-year Kaplan Meier estimate of leukemia-free survival (LFS) was equal to 75% (CO. IN. 57-86); this value was 73% (CO. IN. 52-85) for pts with ALL. LFS of pts who did or did not experience skin-only acute GVHD was 83% (CO. IN. 48-96) and 72% (CO. IN. 50-86), p=NS. The probability of LFS of the 39 pts with either negative or low (<1x10-4) MRD at time of HSCT was 81% (CO. IN. 62-91) as compared to 25% (CO. IN. 1-67) of the 6 pts with positive MRD (p<0.01). The CI of cytomegalovirus (CMV) reactivation was 53% (CO. IN. 29-68). In the first 45 days after HSCT, circulating T cells mainly consisted of the γδ+ subset, while αβ+ T lymphocytes predominated thereafter. CMV reactivation promoted the expansion of Vδ1+ T cells. Mature NK cells expressing inhibitory KIRs and negative for NKG2A, including also the alloreactive cells, were detectable at 1 month in peripheral blood after HSCT, showing the persistence of transplanted cells with potential anti-leukemia activity. These percentages increased at later time points, reaching values comparable to those found in the HSCT donor.These data indicate that a selective graft manipulation results into effective prevention of both acute and chronic GVHD, rapid recovery of neutrophil and platelet counts and low TRM. Although the median observation time is still limited, also the CI of disease recurrence is encouraging. Post-transplant add-back of limited numbers of αβ+ T cells transduced with the iCasp9 suicide gene could optimize the recovery of this subset in early weeks after HSCT, maximizing immune-mediated viral and leukemia control, without an unacceptable risk of GVHD. Disclosures:No relevant conflicts of interest to declare.

Sequential Therapy Combining Clofarabine and HLA-Haploidentical Hematopoietic Stem Cell Transplantation In The Treatment Of Refractory and Advanced Lymphoma: Feasibility, Toxicity and Early Outcome

Allogeneic hematopoietic stem cell transplantation (HSCT) is a valuable treatment option for patients with relapsed or refractory lymphoma including patients with relapse after a first autologous HSCT. However, outcome in non-remission patients is still poor. Here we report the feasibility and efficacy of a protocol using the concept of sequential therapy with clofarabine induction chemotherapy followed by a HLA-haploidentical HSCT in the treatment of patients with advanced non-remission lymphoma. 16 adults (11 male, median age: 53 years, median comorbidity index: 3) with MCL (n=7), CLL (n=1), AITL (n=2), secondary DLBCL (n=2), DLBCL (n=2), follicular lymphoma (n=1), B- lymphoblastic lymphoma (n=1) were treated between September 2010 and February 2013. After induction-chemotherapy with clofarabine (5x30 mg/m² IV), followed by 3 days of rest, a reduced intensity conditioning (RIC) consisting of fludarabine/cyclophosphamide plus melphalan 110 mg/m2 IV was performed prior to a T-cell replete HLA-haploidentical HSCT. High dose cyclophosphamide (Cy) was administered for post-grafting immuno-suppression followed by mycophenolate mofetil and tacrolimus. The median number of immuno-chemotherapy attempts prior to haploidentical HSCT was 4 including 8 autologous HSCT. None of the patients were in complete remission (CR) prior to haploidentical HSCT. After salvage therapy and prior to haploidentical HSCT, progressive disease (PD) was documented in 9 patients with one patient being primarily refractory, while in 7 patients a partial remission (PR) was observed. Neutrophil engraftment was achieved in 16 patients (100%) within a median of 21 days (range 14-36) and platelet engraftment in 14 patients (88%) within a median of 30 days (range 18-115). No primary graft rejection occured. By day +30 CR was achieved in 4 patients (25%) and PR in 11 patients (69%), whereas 1 patient (6%) showed PD. Full donor chimerism on day +30 was detected in all 16 patients. By day +100, 8 of the 14 evaluated 14 patients (57%) achieved CR, 4 (29%) PR, and only 2 (14%) had relapsed. Full donor chimerism was detected in 13 (93%) patients. The rate of acute GvHD grade II-IV was 31%, while chronic GvHD occurred in 3 of 14 (21%) evaluable patients (21%). Non hematologic regimen-related grade III-IV toxicity was observed in 9 patients (56%), and included most commonly transient elevation of liver enzymes (38%), mucositis (19%), and nausea and vomiting (19%). Creatinine elevation (6%), hand-foot syndrome (6%) and haemorrhagic cystitis (6%) were rare. After a median follow up of 14.5 months (range 5.7-35) 4 patients had relapsed, and 4 patients had died, while death was lymphoma-associated only in one patient. Causes of non-relapse mortality (NRM) were haemorrhagic cerebral bleeding in one patient (day +101), and toxicity/infection in 2 patients (day +141; day +156). Cumulative incidence of NRM was 0% on day +100 and increased up to 20% (7-50) on day +360. Estimated one-year overall survival and progression-free survival were 75% (95 CI 46-90) and 56% (95 CI 30-76), respectively. Sequential therapy combining cloforabine induction-chemotherapy and HLA-haploidentical HSCT using RIC, a T-cell replete graft and high dose Cy post-transplant is feasible, shows a favourable toxicity profile and furthermore achieves significant anti-lymphoid activity in patients with advanced non-remission lymphoma. These early results are promising, but longer follow up is needed. Disclosures: Off Label Use: Clofarabine off label use in adults. Hausmann:Sanofi: Travel support Other. Tischer:Sanofi: Travel support Other.

Different changes of serum cytokines following HLA-identical and HLA haploidentical non-myeloablative allogeneic hematopoietic stem cell transplantation

This study was aimed to investigate the expression difference of serum cytokines in 20 patients receiving HLA-identical nonmyeloablative allogeneic hematopoietic stem cell transplantation (iNAHSCT) and HLA-haploidentical nonmyeloablative allogeneic hematopoietic stem cell transplantation (hiNAHSCT). IL-2, IL-4, IL-6, IL-10, TNF-α, γ-IFN and IL-17 were detected by flow cytometric bead array before and on week 1, 2, 4 after transplantation respectively. The results showed that the IL-2 level was found to be up-regulated at week 1 and 2 after transplantation in iNAHSCT group and in hiNAHSCT group respectively, but there was no difference between these two groups (P > 0.05). The γ-IFN levels was up-regulated at week 4 after transplantation in above-mentioned two groups, but no difference was found between these two groups. The IL-4 level increased at week 2 and 1 after transplantation in iNAHSCT and hiNAHCT groups respectively, but the IL-4 level in iNAHSCT group was higher than that in hiNAHSCT group. The IL-6 level rose at week 1 and 2 after transplant in above mentioned groups respectively, and reached to peak level at week 4 after transplantation, but IL-6 level in hiNAHSCT was higher than that in iNAHSCT group (P < 0.02). The IL-10 level was up-regulated at week 1 and 2 in iNAHSCT and hiNAHSCT groups respectively, but the IL-10 level in iNAHSC was higher than that in hiNAHSCT group. The TNF-α level was up-regulated at week 1 in hiNAHSCT group, but at week 2 in iNAHSCT group after transplantation. The TNF-α level in hiNHASCT group was higher than that in iNAHSCT group (P < 0.01). The IL-17 level was up-regulated at week 1 and week 4 after transplantation in hiNAHSCT and iNAHSCT groups respectively, the IL-17 level in hiNAHSCT group was high as compared with that in iNAHSCT group. It is concluded that the serum cytokine levels are obviously up-regulated in iNAHSCT and hiNHASCT groups, and reach to peak level at week 4 after transplantation. The IL-6, TNF-α and IL-17 level up-regulated significantly in hiNAHSCT group, but the IL-4 and IL-10 level up-regulated significantly in iNAHSCT.

HLA Haploidentical Stem Cell Transplantation After Removal of αβ+ T Lymphocytes and B Lymphocytes Is an Effective Treatment for Children with Life-Threatening, Non-Malignant Disorders

AbstractAbstract 2018▪▪This icon denotes a clinically relevant abstract Introduction.Although HLA haploidentical hematopoietic stem cell transplantation (HSCT) has been largely employed in children with life-threatening non-malignant disorders, the survival of patients given this type of allograft has been reported to be inferior to that of patients transplanted from a compatible, unrelated volunteer (UV). We have recently developed a novel method of ex vivo T-cell depletion based on the selective elimination of αβ+ T cells through labeling with a biotinylated anti-TCR αβ antibody, followed by incubation with an anti-biotin antibody conjugated to paramagnetic beads (CliniMACS®, Miltenyi Biotec, Germany). We also remove B cells through an anti-CD19 monoclonal antibody, to prevent post-transplant EBV-associated lymphoproliferative disease (PTLD). Here, we report the results on 13 patients given this type of allograft. Patients and Methods.Seven patients were males and 6 females, median age at transplantation being 3 yr and 9 mo (range 0.3–28.7). Four patients had severe combined immune deficiency (SCID), three Fanconi anemia (FA), 2 severe aplastic anemia (SAA) and 1 each immune deficiency with polyendocrinopathy, enteropathy, X-linked (IPEX), congenital amegakaryocytic thrombocytopenia (CAMT), hemophagocytic lymphohistiocytosis (HLH) and thalassemia with autoimmune hemolytic anemia. All patients were transplanted from 1 parent (10 from the mother and 3 from the father), the median number of CD34+ cells, αβ CD3+ cells and B cells infused being 17.8×106/kg, 0.64×105/kg and 5.3×106/kg, respectively. Conditioning regimen consisted of treosulfan and fludarabine (FLU) in 7 children (4 SCID, 1 IPEX, 1 HLH and 1 CAMT), FLU and cyclophosphamide in 5 (3 FA and 2 SAA) and busulphan, FLU and thiotepa in 1 child (thalassemia). No patient received pharmacological prophylaxis for graft-versus-host disease (GVHD) after the allograft. All patients were given anti-thymocyte globulin (ATG Fresenius; 3 mg/kg/day) on days -5 through -3 before allografting and, to prevent PTLD, rituximab (200 mg/m2) on day -1. Results.All patients but 2 engrafted, the median time to reach neutrophil and platelet recovery being 13 days (range 8–19) and 11 days (range 7–40), respectively. The 2 patients (1 each with SAA and thalassemia) who had primary graft failure were successfully re-transplanted, the first one from the same parent and the second one from the other parent. No patient experienced secondary graft failure. Grade I/II skin acute GVHD occurred in 3 patients, while no patient had visceral acute GVHD. Limited skin chronic GVHD occurred in 1 of the 8 patients at risk. Two patients (1 with SAA and 1 with CAMT) died from respiratory failure secondary to cytomegalovirus and adenovirus infection at 60 and 80 days after transplantation. Two more patients had episodes of cytomegalovirus re-activation, which were successfully treated with ganciclovir. No patient had EBV-related PTLD. With a median follow-up of 209 days (range 37–543), 11 out of the 13 (84%) patients are alive and disease-free, the Karnofsky/Lansky score being 100. The median chimerism is 100% (range 85–100). Noteworthy, all patients with primary immune disorders and FA are alive and disease-free. T-cell recovery was initially sustained by gd T cells, while, after 45 days from the allograft, αβ T cells predominated. Conclusions.The infusion of B-cell and αβ+ T-cell-depleted hematopoietic progenitors from a HLA-haploidentical parent is an effective treatment option for children with life-threatening congenital or acquired non-malignant disorders. The engraftment rate was high and incidence of acute GVHD was low. The transplantation-related mortality of 15% observed in this cohort is comparable to that observed using a HLA-matched UV. If confirmed in a larger cohort of patients and with a longer follow-up, these results suggest that this transplant option be offered to any child lacking a HLA-identical sibling. Disclosures:No relevant conflicts of interest to declare.

Early Reconstitution of T-Cell Immunity to CMV After HLA-Haploidentical Hematopoietic Stem Cell Transplantation Is a Strong Surrogate Biomarker for Lower Non-Relapse Mortality Rates

Abstract 4191 Introduction:HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is a readily available therapeutic option for patients suffering from high-risk hematological malignancies who lack an HLA-compatible donor or for whom there is no time to find one. To avoid GVHD, haplo-HSCT has been classically performed under conditions of strict T-cell depletion, in the form of CD34-selected (“naked”) grafts. Unfortunately, naked haplo-HSCT is followed by a profound state of immune incompetence, which associates with high non-relapse mortality (NRM) rates, mainly due to opportunistic infections. Over the last decade, different strategies have been developed in order to speed-up immune reconstitution after haplo-HSCT, including the delayed infusion of donor T cells (DLI), the selective depletion of T-cell subsets from the graft or the use of an unmanipulated graft followed by novel strategies of immune suppression. Aim:To analyze in depth the early phenomena of immune reconstitution following haplo-HSCT in order to find early surrogate biomarkers of NRM. Results:From 2004 to 2010, we prospectively studied multiple parameters of T-cell immune reconstitution in 89 pts treated at our Center with haplo-HSCT. Time-points of analysis were pre-transplant, at day 30, day 90 and day 180 post-transplant. Underlying diseases included: high-risk AML 53 pts (60%), ALL 11 pts (12%), CLL 2 pts (2%), tyrosine kinase inhibitors-resistant CML 4 pts (5%), Hodgkin lymphoma 6 pts (7%), NHL 2 pts (2%), MDS with high International Prognostic Scoring System 7 pts (7%), other 4 pts (4%). Eighteen patients (20%) were given prophylactic suicide gene-modified DLI starting at day 30 post-transplant, while 64 patients (80%) received an unmanipulated graft followed by rapamycin until day 100. Overall, the incidence of grade III-IV acute GvHD was as low as 12%. Chronic extensive GvHD developed in 28% of pts. Compared with historical naked haplo-HSCT, the recovery of T-cell counts was accelerated: at day 90, median CD3+ cells were 378 per μL (0–2817), CD4+ 127 (0–804), CD8+ 173 (0–1922). Higher T-cell counts, however, did not clearly associate with lower NRM rates. After the initial expansion of effector memory cells (CD45RA−/CD62L−) in patients given DLI (P<0.01) and of central memory cells (CD45RA−/CD62+) in patients receiving rapamycin (P<0.05), there was a progressive normalization of the memory differentiation phenotype with late appearance of naïve cells (CD45RA+/CD62L+), which displayed a TCR spectratyping complexity score similar to pre-transplant values. Nevertheless, none of these biomarkers performed enough to be considered for surrogating lower NRM rates. In this series at high risk for CMV reactivation (CMV serostatus: H+/D+ 68%, H+/D- 27%) the event was observed in 46 pts (52%) and CMV disease in 8 pts (9%), all treated according to guidelines. By using Receiver Operating Characteristics (ROC) curve analysis of CMV-specific IFN-γ ELISPOT results at day 30–90, we found that cut-off values of 1000 spots/mL allowed to discriminate with high specificity (>95%) pts that did not reactivate the virus at later time points. Strikingly, while in pts with <1000 spots/mL, the 2-yrs NRM rate was 32%, in those with >1000 spots/mL, this was 0% (P<0.05). Interestingly, when comparing NRM rates in pts that achieved or not a CD4+cell value of 200 per μL, the result was not significant (21% vs 30%, P=0.8). Conclusions:These results clearly indicate that the early reconstitution of T-cell immunity to CMV after haplo-HSCT does not only protect from subsequent viral reactivation, but also surrogates for lower NRM rates. Moreover, they warrant the investigation of a CMV-specific IFN-γ ELISPOT cut-off value of 1000 spots/mL as a predictive biomarker in larger, multicenter series. Disclosures:No relevant conflicts of interest to declare.

Feasibility of unmanipulated haploidentical stem cell transplantation using standard GVHD prophylaxis for HLA-homozygous patients

HLA-haploidentical hematopoietic stem cell transplantation (haplo-SCT) in HLA-homozygous patients is accompanied by HLA mismatches only in the host-versus-graft vector, and thus theoretically could be performed with standard graft-versus-host disease (GVHD) prophylaxis. However, the risk of GVHD remains uncertain, and graft failure could be a problem. In this study, we assessed nine HLA-homozygous patients who underwent haplo-SCT. Preparative treatment was cyclophosphamide/total body irradiation-based regimen in five patients, fludarabine/busulfan-based regimen in two, and other regimens in two. GVHD prophylaxis consisted of cyclosporine and methotrexate in seven patients, cyclosporine and mycophenolate mofetil in one, and cyclosporine alone in one. Seven patients achieved neutrophil engraftment and platelet recovery. The median times to neutrophil engraftment and platelet recovery were 15 and 44days, respectively. Two patients developed graft failure, including one who achieved engraftment with a second SCT from the same donor. Grade II GVHD was observed in half of the evaluable patients; grades III and IV were not observed. Two patients died from treatment-related causes. Five patients were alive after a median follow-up period of 563days. The probability of overall survival at 5years was 65%. These findings may serve as a rationale for considering haplo-SCT as a treatment option for HLA-homozygous patients.

Isolation strategies of regulatory T cells for clinical trials: Phenotype, function, stability, and expansion capacity

Recent clinical results demonstrate the highly effective potency of regulatory T cells (Tregs) to control graft-versus-host disease (GvHD). In this presented study, we directly compared different Treg subpopulations in order to define the most promising Treg target cell population for cellular intervention studies with respect to their phenotype, functional properties, stability, and expansion capacity. Different Treg cell populations have been isolated from healthy donors and characterized by fluorescence activated cell sorting (FACS) analysis for their phenotypic marker and purity, functional properties by suppression assay, stability by Treg-specific demethylated region (TSDR) of the Foxp3 promoter and their invitro expansion capacity. The direct comparison of the respective Treg target cell populations identified CD4(+)CD25(hi)CD127(-) and CD4(+)CD25(hi)ICOS(+) Tregs as the most promising Treg population for fresh cell infusions in clinical trials with respect to cell yield, phenotype, function, and stability. The CD4(+)CD25(hi) Tregs qualified as the best candidate for invitro expansion combining a highly stable phenotype with strong suppressive potential and attractive cell yield after repetitive stimulation. The suppressive capacity of freshly isolated CD4(+)CD25(hi)CD45RA(+) and CD49d(-)CD127(-) Tregs is comparable to freshly isolated CD4(+)CD25(hi), but inferior to CD4(+)CD25(hi)CD127(-) and CD4(+)CD25(hi)ICOS(+) Tregs. Invitro expansion of CD4(+)CD25(hi)CD45RA(+) and CD49d(-)CD127(-) Tregs resulted in cell populations with less suppressive potency compared with CD4(+)CD25(hi) expanded Tregs correlating well with a higher TSDR demethylation level. In conclusion, future clinical trials should favor CD4(+)CD25(hi)CD127(-) and CD4(+)CD25(hi)ICOS(+) Tregs for direct Treg cell transfer, whereas CD4(+)CD25(hi) Tregs qualify as best candidate for invitro expansion.

Invariant NKT Cell Reconstitution in Pediatric Leukemia Patients Given HLA-Haploidentical Stem Cell Transplantation Defines Distinct CD4+ and CD4− Subset Dynamics and Correlates with Remission State

Immune reconstitution plays a crucial role on the outcome of patients given T cell-depleted HLA-haploidentical hematopoietic stem cell transplantation (hHSCT) for hematological malignancies. CD1d-restricted invariant NKT (iNKT) cells are innate-like, lipid-reactive T lymphocytes controlling infections, cancer, and autoimmunity. Adult mature iNKT cells are divided in two functionally distinct CD4(+) and CD4(-) subsets that express the NK receptor CD161 and derive from thymic CD4(+)CD161(-) precursors. We investigated iNKT cell reconstitution dynamics in 33 pediatric patients given hHSCT for hematological malignancies, with a follow-up reaching 6 y posttransplantation, and correlated their emergence with disease relapse. iNKT cells fully reconstitute and rapidly convert into IFN-γ-expressing effectors in the 25 patients maintaining remission. CD4(+) cells emerge earlier than the CD4(-) ones, both displaying CD161(-) immature phenotypes. CD4(-) cells expand more slowly than CD4(+) cells, though they mature with significantly faster kinetics, reaching full maturation by 18 mo post-hHSCT. Between 4 and 6 y post-hHSCT, mature CD4(-) iNKT cells undergo a substantial expansion burst, resulting in a CD4(+)<CD4(-) NKT cell ratio similar to that found in healthy adults. In contrast with patients maintaining remission, iNKT cells failed to reconstitute in all eight patients experiencing disease relapse. These findings define the peripheral dynamics of human iNKT cells and suggest a contribution of these cells to maintain remission, possibly via early IFN-γ provision. Adoptive transfer of donor-derived iNKT cells into HLA-haploidentical patients failing to reconstitute these cells might represent a novel therapeutic option to prevent leukemia recurrence.

HLA-Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation Using Depletion of CD3±CD19 in Children and Adolescents: Experience at a Single Institution

HLA-Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation Using Depletion of CD3±CD19 in Children and Adolescents: Experience at a Single Institution

HLA-Haploidentical Hematopoietic Stem Cell Transplantation In An Infant with Malignant Infantile Osteopetorosis.

AbstractAbstract 4585Malignant infantile osteopetrosis is an autosomal recessive disease characterized by a lack of osteoclastic function with incidence of 1: 200,000 to 1: 300,000. In consequence of disturbed bone building and remodeling, affected patients have osteosclerosis, dense fragile bone, and a marked reduction in the bone marrow cavity. Clinical features, such as anemia, thrombocytopenia, hepatosplenomegaly, bone fractures, bone deformity, and cranial nerve entrapment, appear soon after birth or within the first years of life. In the natural course of the disease, only 30% of children can survive to more than six years old. Because osteoclasts are of hematopoietic origin, allogeneic stem cell transplantation is the only curable therapy. Recently, successful HLA-haploidentical hematopoietic stem cell transplantation (HSCT) has been reported for patients without HLA- matched donors. We also present an infant with malignant infantile osteopetrosis who underwent HLA-haploidentical HSCT. A four-month-old boy was referred to our hospital for splenomegaly and pancytopenia. A physical examination revealed failure to thrive, distention of anterior fontanel, and hepatosplenomegaly. Laboratory findings indicated thrombocytopenia and anemia, and elevated alkaline phosphatase. Osteoclasts were hyperplastic in bone marrow. Radiography showed homogeneous and sclerotic bones with absence of corticomedullary junction, and bone marrow scintigraphy showed no accumulation of bone marrow. Subsequently, TCIRG1 mutations are identified. All these findings are compatible with malignant infantile osteopetrosis and the diagnosis was made. We conducted HSCT to revive his osteoclastic function. However, he didn't have HLA-matched donors not only in relatives but also in the bone marrow bank and the cord blood bank of Japan. We attempted HLA-haploidentical bone marrow transplantation (BMT) from his father with written informed consent. The patient was prepared for BMT at 11 months of age by conditioning with busulfan (6 mg/kg × 4/day × 4 days), cyclophosphamide (360mg/m2 × 2 days) and antithymocyte globulin (2 mg/kg/day × 3 days). Prophylaxis for graft-versus-host disease (GVHD) included tacrolimus and short-term methotrexate. Bone marrow nuclear cells (1×109/kg) were collected from his father and transplanted without any manipulations. The engraftment of neutrophils was confirmed on day 9 after BMT. Acute GVHD was limited to the skin (grade I). At 2 months after BMT, neutrophil counts, platelet counts, and hemoglobin level were all within normal limits. Bone marrow scintigraphy revealed a significant uptake in bone marrow. There have been no chronic GVHD up to six months after BMT.HSCT for patients with osteopetrosis is challenging as it is reported that HLA-haploidentical HSCT has the high rate of acute and chronic GVHD. Fortunately, HLA-haploidentical BMT was successful in our patient. This might be due to our regimen for prophylaxis of rejection and GVHD. We used ATG in conjunction with tacrolimus: this regimen may be prophylactic not only for rejection but also for GVHD as previously reported (Schulz et al. Blood 2002; 99: 3458–3460). In conclusion, HLA-haploidentical family donors should be considered as the alternative hematopoietic stem cell source for patients with malignant infantile osteopetrosis in condition without HLA-matched donors. Disclosures:No relevant conflicts of interest to declare.

Negative Effect of KIR Alloreactivity in Recipients of Umbilical Cord Blood Transplantation Depends on Transplantation Conditioning Intensity

Transplant strategies involving natural killer (NK) cell alloreactivity (KIR-ligand mismatch [KIR-L mismatch]) have demonstrated superior outcomes for patients receiving T cell depleted HLA haploidentical hematopoietic stem cell allografts. It is unknown whether KIR-L mismatch has a similar effect in recipients of partially HLA-matched umbilical cord blood (UCB) grafts which contain comparatively few T-cells. We examined the clinical impact of KIR-L mismatch in 257 UCB recipients treated with either a myeloablative (n=155) or reduced intensity (n=102) regimen. After myeloablative conditioning, KIR-L mismatch had no demonstrable effect on grades III–IV acute GVHD (17% [CI, 6–28%] vs. 17% [CI, 10–24], p=.97), transplant-related mortality (TRM) (27% [CI, 14–40%] vs. 18% [CI, 11–25%], p=.19), relapse at 2 yrs (18% [95%CI, 6–30%] vs. 28% [95%CI, 19–27%], p=.37) and survival at 3 yrs (50% [CI, 32–68%] vs. 57% [CI, 47–67%], p=.46). In contrast, following reduced intensity conditioning when the engrafting unit was KIR-L mismatched there was a significantly higher incidence of grades III–IV acute GVHD (42% [CI, 27–59) vs. 13% [CI, 5–21], p < .01). Multivariate analysis confirmed NK cell alloreactivity as the only predictive factor associated with severe acute GVHD was (RR 1.8, CI [1.1–2.9]; p=.02). TRM was higher (27% [CI, 12–42%] vs. 12% [CI, 5–19%], p=.03) and three year survival was poorer (32% [CI, 15–59%] vs. 52% [CI, 47–67%], p=.03) when the engrafting unit was KIR-L mismatched, but relapse was unaffected (39% [95%CI, 21–57%] vs. 47% [95%CI, 34–60%], p=.72). KIR-L mismatch in recipients of a RIC UCB transplant was associated with a significant increased risk of death (RR 1.8, 95%CI, 1.0–3.1, p=.05). This data identify divergent effects of NK cell alloreactivity which are unmasked when comparing myeloablative versus RIC transplant platforms. We conclude that KIR-L mismatch should be avoided in recipients of a reduced intensity UCB transplant.

Non-T-Cell-Depleted HLA-Haploidentical Hematopoietic Stem Cell Transplantation for Children with Hematological Malignancies: Single-Center Pilot Study

Allogeneic hematopoietic stem cell transplantation is the only curative approach for a number of patients with hematological malignancies. For patients who do not have an HLA-identical related or unrelated donor, a related haploidentical transplantation is an alternative option. Recent advances in effective T-cell depletion of stem cells have significantly decreased graft-versus-host disease (GVHD) and early transplantationrelated mortality (TRM). However, the problems related to delayed immune reconstitution causing infectious complications and relapse remain, limiting the efficacy of haploidentical transplantation. Here, we report the results of ten children with hematological malignancies who received non-T-cell-depleted haploidentical hematopoietic stem cell transplantation. Malignancies included acute lymphoblastic leukemia (ALL, n = 6), acute myeloid leukemia (n = 2), chronic myeloid leukemia (n = 1) and Epstein Barr virus (EBV)-associated peripheral T cell lymphoma (n = 1). Median patient age was 5 years, and all patients presented with clinical and biologic features that indicated a very high risk of relapse with conventional chemotherapy. At the time of transplantation, seven patients were in remission, and two of these were urgent cases with primary graft failure of the first cord blood transplantation. The remaining three patients were not in remission. HLA disparity was two loci mismatches in one case and three loci mismatches in nine cases. The conditioning regimen consisted of the myeloablative method in five cases and reduced intensity conditioning in five cases. GVHD prophylaxis was conducted with tacrolimus and short-term methotrexate (sMTX) in the initial two cases and the remaining eight cases were given a combination of tacrolimus, sMTX and prednisolone (PSL). The stem cell source for the initial two cases was peripheral blood stem cells mobilized with G-CSF, and that for the remaining eight cases was bone marrow. Nine (90%) of the ten patients engrafted showed myeloid and platelet recovery on days +15 and +31 (median), respectively. All of these patients achieved full donor chimerism by day +30, and it persisted, except in one patient who relapsed. Acute GVHD of Grades II–IV and III–IV occurred in six (66.7%) and two (22.2%) patients, respectively, all of which responded to temporary augmentation of PSL. Chronic GVHD occurred in five (62.5%) patients, three of whom had extensive GVHD. Although one of these developed steroid refractory chronic GVHD, it was not difficult to control the symptoms of GVHD of the remaining patients. Infectious complications, including cytomegalovirus (CMV) antigenemia (n = 2), interstitial pneumonia associated with CMV (n = 1), temporary elevation of EBVDNA (n = 1), zoster (n = 1), invasive aspergillus infection (n = 1) and sepsis (n = 1), were observed. TRM occurred in two patients, and one patient with ALL relapsed on day +472 after transplantation. The Karnofsky performance scales of six of the eight survivors were 100%, and more than half of the evaluable patients were expected to discontinue immunosuppressive therapy within 2 years after transplantation. Because only one patient had relapsed by the time of the last follow-up, we believe that our GVHD prophylactic regimen suppresses the incidence of both acute and chronic GVHD to an acceptable level, while preserving the graft-versus-leukemia effect. Median follow-up of the eight patients who survived event-free was 34 months (range, 3 to 95 months). The 5-year probability of overall survival and event-free survival (EFS) were 77.6% and 66.6%, respectively. In the analysis of disease status at transplantation, encouraging results were obtained in patients who received the transplantation while in remission, with the rate of engraftment and 5-year probability of EFS at 100% and 80%, respectively. Although the number of patients in this series was small, the results described here indicate the feasibility of non-T-cell-depleted haploidentical stem cell transplantation for children with hematological malignancies who do not have an HLA-identical donor.

Long-Term Survival after HLA-Haploidentical Stem Cell Transplantation from Non-Inherited Maternal Antigen-Mismatched Family Donors: Impact of Chronic Graft-Versus-Host Disease.

Background: We previously reported that T-cell-replete HLA-haploidentical hematopoietic stem cell transplantation (SCT) from a microchimeric noninherited maternal HLA antigen (NIMA)-mismatched related donor offers a feasible treatment option in patients with poor-risk hematologic malignancies who lack an immediately available stem cell source (Ichinohe T, et al. Blood 2004; 104:3821). However, long-term outcomes and late effects among patients undergoing such transplantation are largely unknown.Methods: We studied 16 patients who had survived more than 3 years after T-cell-replete HLA-haploidentical NIMA-mismatched SCT to evaluate the impact of late complications on morbidity and mortality. The patients received bone marrow (n=5) or peripheral blood stem cell (n=11) between 01/2001 and 07/2004 at 11 centers with a median age of 19 years (range, 2 to 56) as treatment for acute myeloid leukemia (n=6), acute lymphoblastic leukemia (n=3), chronic myeloid leukemia (n=4), and other B-cell neoplasms (n=3). At the time of SCT, 6 patients had a chemosensitive disease and 10 had a chemorefractory disease. Type of donor was NIMA-mismatched sibling in 9, mother in 6, and daughter in 1; all patient-donor pairs had two or three serologic mismatches at HLA-A, −B, and −DR in the graft-versus-host direction. Organ-specific symptoms related to chronic graft-versus-host disease (cGVHD) and their severity were evaluated by clinical scoring system proposed by the National Institutes of Health consensus development project.Results: At a median follow-up of 56 months (range, 38 to 74), 13 (81%) of 16 patients were alive and free of their primary disease. One patient was alive with relapsed disease; 2 died from bronchiolitis obliterans at 51 and 52 months in continuous remission. Karnofsky or Lansky performance score among 14 survivors was 100% in 6 (43%), 80–90% in 5 (36%), 70% in 2 (14%), and less than 70% in 1 (7%). Thirteen (81%) patients developed extensive cGVHD and eleven of them experienced organ symptoms corresponding to the consensus score greater than 1. The commonly involved organs (score>1) were lungs (n=5), skin (n=4), eyes (n=3), and liver (n=3). Seven patients were successfully withdrawn from immunosuppressive agents between 3 and 46 months (median, 19) after transplantation.Conclusions: T-cell-replete HLA-haploidentical SCT from a microchimeric NIMA-mismatched donor confers long-term survival in selected patients without compromising their performance status, although a high incidence of moderate to severe cGVHD may limit its usefulness as compared with conventional SCT.

Outcome of Non-T-Cell-Depleted HLA-Haploidentical Hematopoietic Stem Cell Transplantation from Family Donors in Children and Adolescents

Non-T-cell-depleted HLA-haploidentical hematopoietic stem cell transplantation (SCT) from family members has been reported, but its effectiveness and safety are not fully known. In this study, we examined the outcomes of 83 children and adolescents with nonmalignant (n = 11) or malignant (n = 72) disorders who underwent SCT mismatched at 2 or 3 HLA loci, either from the mother (n = 56), a noninherited maternal antigen (NIMA)-mismatched sibling (n = 14), or the father/a noninherited paternal antigen (NIPA)-mismatched sibling (n = 13). Engraftment was satisfactory. Severe (grade III-IV) acute graft-versushost disease (GVHD) was noted only in malignant disease, with an incidence of 21 of 64 evaluable patients. GVHD prophylaxis with a combination of tacrolimus and methotrexate was significantly associated with a lower risk of severe acute GVHD, compared with other types of prophylaxis (P = .04). Nine of 11 patients with nonmalignant disease and 29 of 72 patients with malignant disease were alive at a median follow-up of 26 months (range, 4-57 months). Outcomes were not significantly different among the 3 donor groups (mother versus NIMA-mismatched sibling versus father/NIPA-mismatched sibling) for the malignancy disorders. Our results indicate that non-T-cell-depleted HLA-haploidentical SCT may be feasible, with appropriate GVHD prophylaxis, for young recipients who lack immediate access to a conventional stem cell source.

The Overview of the Short Term Curative Effects of HLA Haploidentical Hematopoietic Stem Cell Transplantation for Hematological Malignancies.

From May 2003, 13 patients with refractory hematological malignancies received HLA haploidentical hematopoietic stem cell transplantations in out BMT center.13 patients, including 9 male and 4 female, are with an average age of 31.4 years (range, 15 to 46). Among them, 4 cases were of accelerated phase of CML, 1 blast phase of CML, 1 polyleptic ANLL-M3, 1 ANLL-M2, 2 ANLL M4, 1 ANLL M6, 2 NHL, and 1 MDS-RA. Of the 13 donors, 8 were the mothers of the recipients, 4 were the siblings, and the rest was the son. All the donors were HLA haploidentical matched to the patients.4 patients were conditioned with CY/TBI/Ara-C regimen, (Ara-C 3. 0g/m2, q12h, ×3 d; CTX45 mg/kg×2 d; TBI 5 Gy ×2 d, ATG5 mg/kg ×4 d)). 8 patients were conditioned with improved BU/CY regimen, (BU 4 mg/kg ×3 d, CTX 1. 8 g/m 2 ×2 d, Ara-C 2 g/m 2 × 1 d, Me-CCNU 250 mg/m 2 ×1 d, ATG5 mg/kg ×4 d) and 1 patient of MDS-RA was conditioned with nonmyeloablative regimen (Fludarabine 30 mg/m2/d × 5d, CTX 30 mg/kg/d x 2d, TBI 300 cGy d1.G-CSF was given to the donors at 250 mg /day for a continuous 5~7 days. On the 4th~8th day, their bone marrow was collected under epidural anesthesia. In the simple bone marrow transplantation, the amount of the bone marrow collected was 15~20 ml/kg recipient b.w. And BMT associated with HSCT was given to 9 of the patients. The average parameter of the mononuclear cells re-infused was 8.84×108/kg; while the CD34+ cells was 2.67×106/kg.The treatments of CsA, MTX, MMF, ATG, and anti-CD25 monoclonal antibody were given as prophylaxis for GVHD. All the 13 patients received standard supportive care, and got hematopoietic reconstitution. The mean time of engraftment with neutrophil count more than 1.0 x 109/L was 15 days and platelet count more than 20 x 109/L was 21 days. All the patients was tested with STR-PCR, and showed a genotype the same as the donor's.5 of the 13 patients suffered grade I~II acute GVHD. 1 patient suffered grade III dermo-GVHD 30 days after transplantation. The CMV-DNA of 3 patients turned out positive after the transplantation, 2 patients suffered grade I~II hemorrhagic cystitis. There were totally 2 deaths, one of which who was in the IV phase of NHL died due to recurrent disease after the transplantation, the other suffered graft rejection on the 28 day of the hematopoietic reconstitution, which complicated with centrum infection after the second transplantation.11 recipients got CR after transplantation. 1 patient of the accelerated phase of CML relapsed on the +70 day and 1 M3 patient relapsed 18 months after transplantation, both of them died after ineffective therapy. One patient of accelerated phase of CML relapsed genetically 1 year after the transplantation, and then got remission after the administration of Glivec. Full donor-type engraftment was sustained successfully in these 8 recipients. The patients were followed up until June 2005, with a median follow-up time of 18 months (range, 12 to 25 months).Our initial results show that the conditioning regimens, either with or without radiotherapy, are able to transplant the haploidentical hematopoietic stem cell without first T lymphocytes depletion. If ATG, mycophenolate mofetil and anti-CD25 monoclonal antibody, etc. are applied, the incidence of severe aGVHD will be decreased. 8 of the 13 patients survived for more than one year after transplantation. It shows favorable short-term curative effects.

No Significant Benefit of Marrow and Blood HLA-Haploidentical Stem Cell Transplantations Given by Mothers with Long-Term Fetomaternal Microchimerism.

Non-T-cell-depleted maternal HLA-haploidentical hematopoietic stem cell transplantations(SCT) have been reported feasible based on the hypothesis that long-term fetomaternal microchimerism(FMC) is linked with hyporesponsiveness to inherited paternal antigens(IPAS),but the hypothesis is still in debate due to lack of direct evidence. To determine whether the existence of such microchimerism affect the outcome of maternal HLA-haploidentical SCT, we investigated the outcomes of 18 patients (median age 19) with hematologic malignancies (ALL 8, AML 6, CML 3, NHL 1) who underwent haploidentical SCT from mothers with the same regime from July 2003 to January 2005. Donor was treated with granulocyte colony stimulating factor subcutaneously at a dose of 300μg per day for 5 days before bone marrow harvesting. Leukaphereses were performed using a continuous-flow blood cell separator if CD34+ cells in the bone marrow harvest were less than 4.0×106 cells/kg. Patients with CML or AML in CR received 7.5Gy TBI based standard-intensity regimen combined with cyclophosphamide plus cytarabine. The remaining received non-TBI standard-intensity regimen consisting of cytarabine, busulfan and cyclophosphamide. Antithymocyte globulin(ATG) at a dosage of 2.5mg/kg/day on days −5 to −3 was given as an additional immunosuppressive measure in all patients. To prevent GVHD, patients also received cyclosporin at a dose of 3mg/kg/day as a continuous infusion from day −10, 30mg/kg/day mycophenolate mofetil starting on day −10, and short-term methotrexate administered on days 1, 3, 6, 11 at doses of 15, 10, 10, and 10mg/m2. Among all these patients, microchimerism were confirmed with nested polymerase chain reaction using sequence-specific primers(PCR-SSP) typing for HLA in 10 donor-recipient pairs. In the 2 categories as to whether the microchimeric status of the donor is positive or negative, they had similar characteristics in the background factors such as recipient sex, type of conditioning regime, stem cell source, and disparity of HLA except recipients of positive group had more CML. Engraftment was obtained in all patients. As of august 1, 2005, 5 patients died (1 of relapse, 4 of complication), other 13 patients were alive and free of disease. The 2-year overall survival for the whole cohort was 58%. Although there was a survival advantage for pairs with microchimerism over pairs without it, the influence on outcome was not statistically significant (P=0.9, log-rank test). The cumulative incidences of grade Ò/Ô acute graft-versus-host disease (GVHD) were 39% (95%CI, 17%–64%). Also no significant difference was observed between the two groups. Extensive chronic GVHD developed in 5 of 13 patients who could be evaluated. These results indicate maternal HLA-haploidentical hematopoietic SCT is a acceptable option for patients who lack immediate access to a conventional stem cell source, but the presence of fetomaternal microchimerism may not correlate to the existence of immunological tolerance between mother and offspring.

Feasibility of HLA-haploidentical hematopoietic stem cell transplantation between noninherited maternal antigen (NIMA)–mismatched family members linked with long-term fetomaternal microchimerism

Based on the hypothesis that long-term fetomaternal microchimerism is associated with acquired immunologic hyporesponsiveness to noninherited maternal antigens (NIMAs) or inherited paternal antigens (IPAs), several groups have recently reported successful cases of non-T-cell-depleted hematopoietic stem cell transplantation (SCT) from HLA-haploidentical family members mismatched for NIMAs. In this study, we examined the outcomes of 35 patients with advanced hematologic malignancies who underwent HLA-2-antigen- or HLA-3-antigen-incompatible SCT from a microchimeric NIMA-mismatched donor. After standard-intensity or reduced-intensity preparative regimens, all patients had sustained hematopoietic recovery with tacrolimus-based graft-versus-host disease (GVHD) prophylaxis. Grade II/IV acute GVHD occurred in 19 (56%) of 34 evaluable patients, while extensive chronic GVHD developed in 13 (57%) of 23 patients who could be evaluated. Multivariate analysis demonstrated that NIMA mismatch in the GVH direction was associated with a lower risk of severe grade III-IV acute GVHD when compared with IPA mismatch (P = .03). Fifteen patients were alive and 14 of them were disease-free with a median follow-up of 20 (range, 8 to 37) months. These results indicate that T cell-replete SCT from an HLA-haploidentical NIMA-mismatched donor can offer durable remission with an acceptable risk of GVHD in selected patients with advanced hematologic malignancies who lack immediate access to a conventional stem cell source.

Reticular dysgenesis: HLA non-identical bone marrow transplants in a series of 10 patients.

Reticular dysgenesis is a very rare congenital immunodeficiency classified within the severe combined immunodeficiencies (SCID) and characterized by impairment of both lymphoid and myeloid cell development. We report our experience in 10 patients with RD, treated between 1979 and 1999 with HLA-haploidentical hematopoietic stem cell transplantation (HSCT). All children but one were symptomatic within the first days of their lives. Five patients required two HSCT. Five patients received conditioning therapy with busulfan (16 mg/kg) and cyclophosphamide. Three of them are alive and well with myeloid and T and B cell lymphoid reconstitution, whereas two patients died (one chronic graft-versus-host disease, one pneumonitis). Transplantation without or with other conditioning regimens in the other five cases led to absent or incomplete engraftment and none of these cases survived. These results demonstrate the mandatory need for intensive conditioning before haploidentical HSCT in RD to achieve full lymphoid and myeloid engraftment.