The addition of sirolimus to the graft‐versus‐host disease prophylaxis regimen in reduced intensity allogeneic stem cell transplantation for lymphoma: a multicentre randomized trial

Inhibition of the mechanistic target of rapamycin (mTOR) pathway has clinical activity in lymphoma. The mTOR inhibitor sirolimus has been used in the prevention and treatment of graft‐versus‐host disease (GVHD) after allogeneic haematopoietic stem cell transplantation (HSCT). A retrospective study suggested that patients with lymphoma undergoing reduced intensity conditioning (RIC) HSCT who received sirolimus as part of their GVHD prophylaxis regimen had a lower rate of relapse. We therefore performed a multicentre randomized trial comparing tacrolimus, sirolimus and methotrexate to standard regimens in adult patients undergoing RIC HSCT for lymphoma in order to assess the possible benefit of sirolimus on HSCT outcome. 139 patients were randomized. There was no difference overall in 2‐year overall survival, progression‐free survival, relapse, non‐relapse mortality or chronic GVHD. However, the sirolimus‐containing arm had a significantly lower incidence of grade II‐IV acute GVHD (9% vs. 25%, P = 0·015), which was more marked for unrelated donor grafts. In conclusion, the addition of sirolimus for GVHD prophylaxis in RIC HSCT is associated with no increased overall toxicity and a lower risk of acute GVHD, although it does not improve survival; this regimen is an acceptable option for GVHD prevention in RIC HSCT. This trial is registered at clinicaltrials.gov (NCT00928018).     

Short Report: Engraftment of T-cell-depleted allogeneic haematopoietic stem cells using a reduced intensity conditioning regimen

Graft-versus-host disease (GVHD) remains a significant complication in patients undergoing allogeneic stem cell transplantation (SCT) using a reduced intensity conditioning regimen. Although T-cell depletion (TCD) reduces the risk of GVHD after a myeloablative conditioning regimen, it is associated with an increased risk of graft failure. We have therefore examined whether TCD compromises engraftment using a fludarabine-based conditioning regimen. Fifteen patients have been transplanted using such a regimen of whom 13 underwent ex vivo TCD. All but one patient demonstrated durable engraftment and no patient receiving a TCD product developed severe GVHD. Thus, TCD may play a role in GvHD prophylaxis using such regimens.     

Reduced intensity conditioning in unrelated donor transplantation for refractory cytopenia in childhood

Myelodysplastic syndromes (MDS) are a heterogenous group of acquired hematopoietic stem cell disorders. Refractory cytopenia (RC) is the most common subtype of childhood MDS and hematopoietic stem cell transplantation (HSCT) is the only curative treatment. HSCT following a myeloablative preparative regimen is associated with a low probability of relapse and considerable transplant-related mortality. In the present European Working Groups of MDS pilot study, we investigated whether a reduced intensity conditioning regimen (RIC) is able to offer reduced toxicity without increased rates of graft failure or relapse. Nineteen children with RC were transplanted from an unrelated donor following RIC consisting of fludarabine, thiotepa and anti-thymocyte globulin. Three patients experienced graft failure. Neutrophil and platelet engraftment occurred at a median time of 23 and 30 days, respectively. Cumulative incidence of grade II-IV and grade III and IV acute graft-versus-host disease (GVHD) was 0.48 and 0.13, respectively; three patients developed extensive chronic GVHD. Although infections were the predominant complications, only one patient with extensive chronic GVHD died from infectious complications. Overall and event-free survival at 3 years were 0.84 and 0.74, respectively. In conclusion, our results were comparable to those of patients treated with myeloablative HSCT. Long-term follow-up is needed to demonstrate the expected reduction in long-term sequelae.     

Hematopoietic stem cell transplantation for sickle cell disease: The changing landscape

Allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative therapy for sickle cell disease (SCD); however, its use is limited by lack of suitable human leukocyte antigen (HLA)-matched donors and decreased application in older patients with significant morbidity. Myeloablative, HLA-identical sibling transplantation in children with SCD offers excellent long-term survival, with overall and event-free survival rates of 95% and 92%, respectively. However, the risk of graft-versus-host-disease, infections, infertility, and other long-term transplant complications, further limits its widespread use. Recent approaches using reduced intensity conditioning (RIC) are associated with lower toxicity, allowing extension of this modality to children and adults with significant morbidity; however, these approaches are also associated with increased risk of graft failure. The optimal RIC regimen that strikes the optimal balance between maximizing the rate of stable engraftment while minimizing transplant-related morbidity and mortality is unknown. Alternative donor transplants, most prominently, partial HLA-mismatched related transplants (haploidentical), are being investigated with promising initial results. This review will discuss long-term results of HLA-matched sibling HSCT for SCD, and recent updates on HLA-matched unrelated donor and unrelated umbilical cord blood HSCT for SCD.     

Haploidentical hematopoietic cell transplantation

Haploidentical hematopoietic stem cell transplantation (HSCT) provides an opportunity for nearly all patients to benefit from HCT when a HLA genotypically matched sibling is not available. Initial results with the use of mismatched allografts led to limited enthusiasm due to GVHD and infectious complications resulting in unacceptable treatment-related morbidity and mortality. Recent advances with effective T-cell depletion, the use of 'megadoses' of stem cells, better antimicrobial therapy and reduced intensity conditioning has significantly decreased the early transplant-related mortality and GVHD. These modifications also enabled robust and prompt engraftment and led to enhancing the therapeutic benefits of haploidentical transplantation. However, the cardinal problems related to delayed immune reconstitution causing post-transplant infectious complications and relapse remain, limiting the efficacy of haploidentical transplant. Preliminary data have demonstrated the great potential in the use of adoptive cellular immunity and selective allodepletion in rapidly reconstituting immunity without GVHD. The encouraging reports from haploidentical transplant using noninherited maternal antigen (NIMA)-mismatched donors or natural killer (NK) alloreactive donors may greatly increase the donor availability and open a way to more appropriate donor selection in HLA-haploidentical HSCT. Future challenges remain in determining the safest approach for haploidentical transplant with minimal risk of GVHD, while preserving effective GVL activity and promoting prompt immune reconstitution.     

Successful treatment of chronic granulomatous disease with fludarabine-based reduced-intensity conditioning and unrelated bone marrow transplantation

Allogeneic hematopoietic stem-cell transplantation (HSCT) for chronic granulomatous disease (CGD) with a reduced-intensity conditioning regimen can be expected to lead to less therapy-related mortality and late-onset impairment, whereas it has also been reported to increase the risk of unsustained mixed donor chimerism and late rejection after transplantation. Herein, we report a 4-year-old boy with CGD who was successfully treated with unrelated bone marrow transplantation with a reduced-intensity conditioning regimen (RIC). Fludarabine-based RIC, 4 Gy of total body irradiation, 120 mg/kg of cyclophosphamide, and 125 mg/m² of fludarabine, was adopted for transplantation, followed with 8.9 × 10⁸/kg mononucleated donor cells infused without T-cell depletion. Although hematopoietic engraftment was rapidly obtained by day +17, he developed unstable donor chimerism. After tacrolimus withdrawal, the patient showed grade III acute graft-versus-host disease (GVHD), and subsequently reached full donor chimerism by day +61. Twelve months post-transplant, the patient has remained well with stable and durable engraftment, 100% donor chimerism, and normal superoxide production, without the requirement of donor lymphocyte infusions (DLI).     

Nonmyeloablative allogeneic hematopoietic stem cell transplant using mismatched/haploidentical donors: a review

Haploidentical hematopoietic stem cell transplantation (HSCT) provides an opportunity for patients to benefit from HCT when a human leukocyte antigen (HLA) genotypically matched sibling is not available. Initial results with the use of mismatched allograft has been disappointing due to the high incidence of graft-versus-host disease (GVHD) and infectious complications resulting in an unacceptable treatment-related morbidity and mortality. Recent advances with effective T-cell depletion, the use of 'megadose' of stem cells and reduced intensity conditioning has significantly decreased the early transplant related mortality and GvHD, while enabling robust and prompt engraftment, and hence enhancing the therapeutic benefits of haploidentical transplantation. However, the cardinal problems related to delayed immune reconstitution causing posttransplant infectious complications and relapse remain, limiting the efficacy of haploidentical transplant. Preliminary data have demonstrated the great potential in the use of adoptive cellular immunity and selective allodepletion in rapidly reconstituting immunity without GvHD. The encouraging reports from haploidentical transplant using noninherited maternal antigen (NIMA)-mismatched donors or natural killer alloreactive donors may greatly increase the donor availability and open a way to more appropriate donor selection in HLA-haploidentical HSCT. Future challenges remain in determining the safest approach for haploidentical transplant to be performed with minimal risk of GvHD, while preserving effective graft-versus-leukemia activity and promoting prompt immune reconstitution.     

Reduced-intensity conditioning followed by allografting of CD34-selected stem cells and ≤106/kg T cells may have an adverse effect on transplant-related mortality

In patients undergoing allogeneic peripheral blood stem cell (PBSC) transplantation after reduced-intensity conditioning (RIC), graft-versus-host disease (GVHD) represents a major cause of morbidity and mortality. T-cell depletion (TCD) prevents GVHD but carries potential risks of graft failure, opportunistic infections, and disease relapse. We explored ex vivo TCD of stem cell allografts that were administered after RIC treatment. Thirteen high-risk patients with hematological malignancies were treated with a fludarabine/melphalan-based RIC regimen followed by transplantation of immunomagnetically selected CD34⁺ PBSC from HLA-identical sibling or matched unrelated donors. Patients were sequentially enrolled in two cohorts: group A (n=6) received antithymocyte globulin (ATG) during conditioning and 10⁵ donor T cells/kg at transplantation, while group B (n=7) received 10⁶ donor T cells/kg without ATG pretreatment. Primary graft failure occurred in two patients of group A and in one patient of group B. Complete donor chimerism persisting more than 1 year was achieved in two cases per cohort. Acute grade II to IV or chronic extensive GVHD were observed in a total of six patients (group A, 2; group B, 4). Procedure-related deaths were mainly due to severe pneumonia occurring in two patients of group A and in five patients of group B. These results suggest that CD34 selection of reduced-intensity PBSC allografts may cause adverse effects upon specific antimicrobial immunity which can lead to fatal infections, particularly in high-risk patients. In our study, simultaneous add-back of 10⁶/kg donor T cells was unable to compensate for this deficiency.The clinical trial presented herein as well as all experiments performed in this study comply with the current Federal Laws of Germany and have been approved by the local Ethics Committee.     

A comparison of Campath and Thymoglobulin as part of the conditioning before allogeneic hematopoietic stem cell transplantation

Background: In vivo T‐cell depletion with anti‐thymocyte globulin is a commonly used strategy for the prevention of graft‐versus‐host disease (GVHD) and to avoid rejection after hematopoietic stem cell transplantation (HSCT). Methods: We compared 36 patients given Campath (alemtuzumab) as part of the conditioning with a matched cohort of 72 patients receiving Thymoglobulin (TMG). Most patients had a hematologic malignancy beyond first remission. Median age was 55 (1–67). The majority of patients had an unrelated donor (70%) and 82% were given peripheral blood stem cells. Most patients received reduced‐intensity conditioning. Results: Graft failure occurred in 8% of the patients in each group. No difference in time‐to‐engraftment of neutrophils and platelets was found. The cumulative incidence of acute GVHD of any grade was 34% and 53% (P = 0.07), and the incidence of chronic GVHD was 46% and 25% in the Campath and TMG groups, respectively. In multivariate analysis, a low antibody dose was associated with acute and chronic GVHD and Campath was correlated with chronic GVHD. No differences in transplant‐related mortality (28% vs. 18%), overall survival (54% vs. 58%), and relapse‐free survival (39% vs. 43%) were found between the two groups. No difference in the proportion of T and B lymphocytes during the first year after HSCT was found. Conclusions: TMG and Campath as part of the conditioning result in similar outcome. Campath was associated with less acute but more chronic GVHD.     

Early matched sibling hematopoietic cell transplantation for adult AML in first remission using an age-adapted strategy: long-term results of a prospective GOELAMS study

The LAM2001 phase 3 trial, involving 832 patients with acute myeloid leukemia (AML; median: 46 years) proposed HLA-identical sibling allograft HSCT for all patients with an identified donor. The trial compared reduced-intensity conditioning (RIC) for patients older than 50 years of age (N = 47) and myeloablative conditioning for younger patients (N = 117). BM HSCT was performed in the younger patients, while the older ones received a consolidation course, followed by peripheral blood allo-HSCT using RIC. The incidence of grade II-IV acute GVHD, was 51.9% (95% confidence interval [CI]: 42.1-61.8) and 11.3% (1.6-21.2) after myeloablative or RIC, respectively (P < .0001) and that of chronic GVHD 45.8% (95% CI: 34.8-56.7) and 41.7% (24.7-58.6; NS). Cumulative incidence of nonrelapse mortality at 108 months was 15.8% (95% CI: 9.8-23.2) for myeloablative, and 6.5% (0.2-16.2) for RIC (NS). CI of relapse at 108 months was 21.7% (95% CI: 13.9-28.6) and 28.6% (16.5-43.4; NS). Overall survival at 108 months was 63.4% (95% CI: 54.6-72.2) and 65.8% (52.2-72.2), respectively, after myeloablative or RIC (NS). RIC peripheral blood stem cell allo-HSCT is prospectively feasible for patients between the ages of 51 and 60 years without excess of relapse or nonrelapse mortality, and compares favorably with myeloablative marrow allo-HSCT proposed to younger patients.     

Cytomegalovirus seropositivity adversely influences outcome after T-depleted unrelated donor transplant in patients with chronic myeloid leukaemia: the case for tailored graft-versus-host disease prophylaxis

Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after haematopoietic stem cell transplantation from matched unrelated donors (MUD). The role of T-cell depletion (TCD) as a strategy to prevent GVHD is controversial because of the associated increased risk of leukaemic relapse, graft failure and delayed immune reconstitution. The demonstration that donor lymphocyte infusion (DLI) is effective salvage therapy if patients relapse after transplantation for chronic myeloid leukaemia (CML) prompted us to examine the proposal that TCD may be a form of GVHD prophylaxis particularly suited to this disease in patients undergoing MUD transplantation. We analysed the outcome of 106 consecutive patients with CML in first chronic phase who underwent MUD transplantation. Patients were conditioned with cyclophosphamide and total body irradiation (TBI), and received in vivo TCD, using CD52 monoclonal antibody, as GVHD prophylaxis. Donor lymphocytes were infused at the time of leukaemic relapse. The projected survival at 5 years for all patients was 52.6%. The probability of developing severe acute GVHD (grade 3 or 4) was 14.5%. The only significant predictor of overall survival in univariate and multivariate analysis was patient cytomegalovirus (CMV) serostatus: in CMV-negative patients survival at 5 years was 60% vs. 42% in CMV-positive patients (P = 0.006). The use of TCD was associated with an increased risk of relapse (62% probability at 5 years after transplant), but 80% of patients who received DLI achieved molecular remission that was durable in all but two cases. In vivo TCD, in conjunction with DLI at relapse, is a valuable GVHD prophylactic regimen in CMV-seronegative recipients of MUD allografts, but in CMV-seropositive patients this approach is associated with an increased non-relapse mortality. Consequently, GVHD prophylactic regimens in MUD transplantation should be tailored according to the patient and donor pretransplant characteristics.     

Reduced-intensity conditioning using fludarabine and antithymocyte globulin alone allows stable engraftment in a patient with dyskeratosis congenita

Dyskeratosis congenita (DC) is a rare inherited disorder characterized by the triad of nail dystrophy, mucosal leukoplakia, and reticular pigmentation. Bone marrow failure is the principal cause of early mortality, and stem cell transplantation is the only cure for these patients. However, the results of conventional hematopoietic stem cell transplantation (HSCT) for patients with DC are poor because of the high incidence of transplant-related complications. We describe the successful treatment of a 21-year-old male with DC by nonmyeloablative HSCT from a matched unrelated donor. The gene responsible for the X-linked form of DC was screened and hemizygosity for the mutation Gln31Lys was found, which is consistent with the diagnosis. The conditioning regimen consisted of only fludarabine and antithymocyte globulin. Additionally, a graft-versus-host disease (GVHD) prophylaxis was administered with cyclosporine A (CSA) and mycophenolate mofetil (MMF). The regimen was well tolerated, no severe posttransplantation complications were observed, and engraftment was rapid and complete (granulocytes on day +11 and platelets on day +13). Seven months after HSCT, the patient developed GVHD of the liver after tapering CSA which was successfully treated with prednisolone, CSA, and MMF. At the time of reporting, 3 years after HSCT, the patient remained in good clinical condition with minimal signs of chronic GVHD of the oral mucosa. Thus, we conclude that a low-intensity conditioning regimen might be sufficient to induce permanent engraftment by using matched unrelated donor HSCT in DC patients and may avoid severe organ toxicity. Although allogeneic HSCT in patients with DC will not cure the underlying genetic defect it may significantly prolong survival through effective therapy for hematologic complications.     

Haematopoietic stem cell transplantation for refractory Langerhans cell histiocytosis: outcome by intensity of conditioning

Patients with Langerhans cell histiocytosis (LCH) refractory to conventional chemotherapy have a poor outcome. There are currently two promising treatment strategies for high‐risk patients: the first involves the combination of 2‐chlorodeoxyadenosine and cytarabine; the other approach is allogeneic haematopoietic stem cell transplantation (HSCT). Here we evaluated 87 patients with high‐risk LCH who were transplanted between 1990 and 2013. Prior to the year 2000, most patients underwent HSCT following myeloablative conditioning (MAC): only 5 of 20 patients (25%) survived with a high rate (55%) of transplant‐related mortality (TRM). After the year 2000 an increasing number of patients underwent HSCT with reduced intensity conditioning (RIC): 49/67 (73%) patients survived, however, the improved survival was not overtly achieved by the introduction of RIC regimens with similar 3‐year probability of survival after MAC (77%) and RIC transplantation (71%). There was no significant difference in TRM by conditioning regimen intensity but relapse rates were higher after RIC compared to MAC regimens (28% vs. 8%, P = 0·02), although most patients relapsing after RIC transplantation could be salvaged with further chemotherapy. HSCT may be a curative approach in 3 out of 4 patients with high risk LCH refractory to chemotherapy: the optimal choice of HSCT conditioning remains uncertain.     

Treatment with mesenchymal stromal cells is a risk factor for pneumonia-related death after allogeneic hematopoietic stem cell transplantation

We performed a retrospective cohort study to find out whether the use of reduced‐intensity conditioning (RIC) might reduce the risk of early death from pneumonia. Pneumonia‐associated deaths were evaluated in 691 hematopoietic stem cell transplantation (HSCT) patients. The majority had a hematological malignancy (n = 504) and an HLA‐matched donor (n = 584). RIC was given to 336 patients and myeloablative conditioning (MAC) to 355. Data concerning radiology, culture and autopsy results were evaluated together with risk factors for death related to pneumonia within or after 100 d after HSCT (early and overall pneumonia). In 60 patients, pneumonia contributed to death (early n = 17). The cumulative incidence of early pneumonia‐related death was 2.8% and 2.1% in MAC and RIC patients, respectively. The cumulative incidence of overall pneumonia‐related death was 8.2% and 10.5%, respectively. In 40 patients, (67%) an etiology could be established, with 19 patients having proven or probable mold infection. In the multivariate analyses, acute graft‐versus‐host disease (GVHD) grades II–IV, cytomegalovirus (CMV) infection and having received mesenchymal stromal cells (MSCs) were factors associated with overall pneumonia‐related death. Bacteremia and a previous HSCT were associated with early pneumonia‐related death. RIC did not reduce the incidence of early death associated with pneumonia. Acute GVHD II–IV, CMV infection and MSC treatment were factors associated with pneumonia‐related death. Mold infection was the most common contributor to pneumonia‐related death in HSCT patients.     

Bone marrow as stem cell source for allogeneic HLA-identical sibling transplantation following reduced-intensity preparative regimen

OBJECTIVE: Reduced-intensity conditioning regimens (RIC) and peripheral blood stem cells (PBSC) are increasingly used for allogeneic stem cell transplantation (allo-BMT). RIC has been shown to allow engraftment with minimal early transplant-related mortality (TRM). However, in the context of RIC, the use of bone marrow (BM) as stem cell source is still little evaluated. PATIENTS AND METHODS: In this report, we analyzed the outcome of 32 high-risk patients with hematological malignancies who received an HLA-identical sibling allo-BMT after RIC including fludarabine, busulfan, and anti-thymocyte globulin (ATG). RESULTS: Sustained neutrophil and platelet recovery occurred at a median of 13 days (range, 10-19) and 17 days (range, 0-45) respectively. Early and durable full donor chimerism could be established as soon as the first month after allo-BMT. Also, a sustained and early CD8(+) T-cell recovery was observed, but the CD4(+) T-cell compartment remained profoundly low. The cumulative incidences of grade II-IV acute GVHD and chronic GVHD were 26% (95% CI, 11-41%) and 31% (95% CI, 15-47%) respectively. The overall cumulative incidence of TRM was 28% (95% CI, 12-44%) occurring mainly in patients aged over 50. In this setting, GVHD showed a protective effect on disease progression or relapse with better progression-free survival for patients with GVHD as compared to patients without GVHD (p=0.03). CONCLUSIONS: Collectively, these results confirm that the use of BM grafts for RIC is feasible with durable donor engraftment and no detrimental GVHD.     

Stem cell transplantation after reduced‐intensity conditioning for sickle cell disease

Sickle cell disease (SCD) is still associated with substantial morbidity and reduced life expectancy. Disease‐related mortality rises to 14% in adolescents and young adults. Overall and disease‐free survival following haematopoietic stem cell transplantation (HSCT) is 90% and 95%, respectively. To reduce transplant‐associated late effects, the feasibility of a highly immunosuppressive reduced‐intensity conditioning (RIC) regimen was explored in children with SCD and a matched sibling donor. Eight patients (median age, 9 yr) and symptomatic SCD were included. The conditioning regimen consisted of fludarabine, melphalan and either thiotepa or total lymphoid irradiation plus antithymocyte globuline or alemtuzumab. The graft was bone marrow in seven and cord blood in one case. The conditioning regimen was well tolerated and no severe infectious complications occurred. All patients displayed mixed chimaerism on day +28. After a median follow‐up of 4 yr, 3/8 patients have mixed leucocyte chimaerism and 8/8 patients have 100% donor erythropoiesis. HSCT from matched sibling donors following a RIC regimen was well tolerated and resulted in cure in all patients studied. If confirmed in larger patient cohorts, these observations will have important implications for the indications of HSCT in children with SCD.     

Antibody and pre- plus post-transplant prednisone treatments support T cell-depleted stem cell engraftment without drug-induced morbidity

Rigorous T cell depletion methods can now be used to reduce the risk of graft-versus-host disease (GVHD) associated with allogeneic, hematopoietic stem cell transplantation (HSCT). However, full T cell depletion is also associated with a significant risk of graft failure. Here we hypothesize that engraftment failures after T cell-depleted HSCT may be due, in part, to the absence of GVHD prophylaxis. To test this hypothesis, we used a haploidentical mouse model to systematically measure the effects of immunosuppressive drug treatments and anti-T cell antibodies on engraftment. Results showed that engraftment was supported in all animals when hosts were pre-treated with anti-T cell antibodies, but donor chimerism was significantly improved when hosts were also treated with prednisone. Interestingly, when hosts received only pre-HSCT prednisone treatments, engraftment was not improved; when hosts received only post-HSCT prednisone (initiated near the time of irradiation), the animals became extremely ill. Results therefore demonstrated the need for both pre- and post-HSCT prednisone treatments as a means to ensure engraftment without morbidity in all host animals.     

Induction of transplantation tolerance in haploidenical transplantation under reduced intensity conditioning: the role of ex-vivo generated donor CD8+ T cells with central memory phenotype

Haploidentical hematopoietic stem cell transplantation (HSCT) offers the advantage of readily available family member donors for nearly all patients. A 'megadose' of purified CD34+ hematopoietic stem cells is used to overcome the host's residual immunity surviving the myeloablative conditioning, while avoiding severe GVHD. However, the number of CD34+ cells that can be harvested is insufficient for overcoming the large numbers of host T cells remaining after reduced intensity conditioning (RIC). Therefore, combining a 'megadose' of CD34+ HSCT with other tolerizing cells could potentially support and promote successful engraftment of haploidentical purified stem cell transplantation under a safer RIC. One approach to address this challenge could be afforded by using Donor CD8 T cells directed against 3rd-party stimulators, bearing an ex-vivo induced central memory phenotype (Tcm). These Tcm cells,depleted of GVH reactivity, were shown to be highly efficient in overcoming host T cells mediated rejection and in promoting fully mismatched bone-marrow (BM) engraftment, in HSCT murine models. This is likely due to the marked lymph node homing of the Tcm, their strong proliferative capacity and prolonged persistence in BM transplant recipients. Thus, combining anti 3rd-party Tcm cell therapy with a 'megadose' of purified CD34+ stem cells, could offer a safer RIC protocol for attaining hematopoietic chimerism in patients with hematological diseases and as a platform for organ transplantation or cell therapy in cancer patients.     

The gut mucosa barrier is preserved during allogeneic, haemopoietic stem cell transplantation with reduced intensity conditioning.

The efficacy of allogeneic, haemopoietic stem cell transplantation (HSCT) is limited by concomitant toxicity. This has led to the development of less toxic, reduced intensity conditioning (RIC) protocols, whose therapeutic benefit is largely related to an associated, immunity-mediated graft-versus-malignancy effect rather than by the cytotoxic treatment itself. Murine HSCT models suggests that acute graft-versus-host disease (GVHD) increases with the intensification of the conditioning regimen mediated by loss of integrity of the gut mucosa barrier. The present study was undertaken to investigate gastro-intestinal (GI) permeability during allogeneic HSCT with RIC. In 17 patients (myeloablative conditioning in nine, RIC in eight), intestinal permeability was assessed by a (51)Cr-EDTA absorption test before the start of cytotoxic treatment the day before stem cell infusion (day -1) and 4, 7 and 14 days after stem cell infusion. Patients receiving RIC did not develop any significant increase in intestinal permeability during the transplantation course but in myeloablatively conditioned patients there was a significant increase in intestinal permeability the day before the stem cell infusion (P < 0.005), on day 4 (P < 0.005), on day 7 (P < 0.01) and on day 14 (P < 0.005) after stem cell infusion, compared with the baseline. Myeloablative conditioning also revealed increased intestinal permeability on day 7 compared with the RIC (P < 0.05). The finding of preserved intestinal-barrier function during allogeneic HSCT with RIC is discussed, with reference to the hypothesis that GI tract damage may be an important initiating event of GVHD.     

Outcomes of transplantation with partial T-cell depletion of matched or mismatched unrelated or partially matched related donor bone marrow in children and adolescents with leukemias

Graft-versus-host disease (GVHD) remains a major barrier to successful hematopoietic stem cell transplant for patients who lack a matched related donor. Partial T-cell depletion (TCD) of the graft may decrease the risk of severe GVHD with unrelated donors (URD) and partially matched related donors (PMRD) while retaining an antileukemic effect. We analyzed our experience using URD and PMRD for pediatric patients with leukemias from 1990 to 2001. A subgroup of 'matched' URD donor pairs was retrospectively analyzed for high-resolution class I. Partial TCD was accomplished with monoclonal antibody T10B9 or OKT3 and complement. There were 76 URD (45% matched) and 28 PMRD recipients. Event-free survival (EFS) was 38.3%, and overall survival (OS) 45.1% at 3 years. On multivariate analysis, there was no difference in survival based upon marrow source, but nonrelapse mortality was higher with the use of PMRD. Relapse occurred in 6% of ALL patients, and 22.8% of AML/MDS patients. Grades III-IV GVHD was observed in only 6.7% of patients. Partial TCD allows use of matched or mismatched URD, or PMRD with little mortality from GVHD, durable engraftment, and no increase in relapse risk.