Anti-CD25 monoclonal antibody (basiliximab) for prevention of graft-versus-host disease after haploidentical bone marrow transplantation for hematological malignancies

Lower dose of ATG combined with basiliximab for haploidentical hematopoietic stem cell transplantation is associated with effective control of GVHD and less CMV viremia

Currently, the graft-versus-host disease (GVHD) prophylaxis consists of an immunosuppressive therapy mainly based on antithymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). GVHD remains a major complication and limitation to successful allogeneic haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We modified the ATG-based GVHD prophylaxis with the addition of basiliximab in the setting of haplo-HSCT and attempted to explore the appropriate dosages. We conducted a retrospective analysis of 239 patients with intermediate- or high-risk hematologic malignancies who received haplo-HSCT with unmanipulated peripheral blood stem cells combined or not with bone marrow. All patients received the same GVHD prophylaxis consisting of the combination of methotrexate, cyclosporine or tacrolimus, mycofenolate-mofetil, and basiliximab with different doses of ATG (5-9mg/kg). With a median time of 11 days (range, 7-40 days), the rate of neutrophil engraftment was 96.65%. The 100-day cumulative incidences (CIs) of grade II-IV and III-IV aGVHD were 15.8 ± 2.5% and 5.0 ± 1.5%, while the 2-year CIs of total cGVHD and extensive cGVHD were 9.8 ± 2.2% and 4.1 ± 1.5%, respectively. The 3-year CIs of treatment-related mortality (TRM), relapse, overall survival (OS), and disease-free survival (DFS) were 14.6 ± 2.6%, 28.1 ± 3.4%, 60.9 ± 3.4%, 57.3 ± 3.4%, respectively. Furthermore, the impact of the reduction of the ATG dose to 6 mg/kg or less in combination with basiliximab on GVHD prevention and transplant outcomes among patients was analyzed. Compared to higher dose of ATG(>6mg/kg), lower dose of ATG (≤6mg/kg) was associated with a significant reduced risk of CMV viremia (52.38% vs 79.35%, P<0.001), while the incidences of aGVHD and cGVHD were similar between the two dose levels. No significant effect was found with regard to the risk of relapse, TRM, and OS. ATG combined with basiliximab could prevent GVHD efficiently and safely. The optimal scheme of using this combined regimen of ATG and basiliximab is that administration of lower dose ATG (≤6mg/kg), which seems to be more appropriate for balancing infection control and GVHD prophylaxis.

Infusion of haploidentical HSCs combined with allogenic MSCs for the treatment of ALL patients

Although haploidentical stem cell transplantation (haplo-HSCT) offers almost all acute lymphoblastic leukaemia (ALL) patients an opportunity for immediate transplantation, it exhibits a higher incidence of graft failure and graft versus host disease (GVHD). Mesenchymal stem cells (MSCs) are characterised by their haematopoiesis-promoting and immunomodulatory capacity. Thus, we designed a combination of haplo-HSCT and MSCs for ALL patients. ALL patients (n = 110) were given haploidentical HSCs combined with allogenic MSCs, and ALL patients without MSC infusion (n = 56) were included as controls. The 100-day cumulative incidences of grade ≥2 acute GVHD (aGVHD) and grade ≥3 aGVHD were 40.00% and 9.09% compared to 42.32% (P = 0.79) and 22.79% (P = 0.03) in patients without MSC infusion, respectively. The 3-year cumulative incidences of chronic GVHD (cGVHD) and extensive cGVHD were 22.27% and 10.27% compared to 32.14% (P = 0.19) and 22.21% (P = 0.04) in patients without MSC infusion, respectively. No significant differences in the 3-year relapse incidence, nonrelapse mortality, leukaemia-free survival or overall survival in groups with and without MSC cotransplantation were observed. Multivariate analysis showed that MSC infusion contributed to a lower risk of developing extensive cGVHD. Our data suggested that haplo-HSCT combined with MSCs may provide an effective and safe treatment for ALL patients.

Infusion of haploidentical hematopoietic stem cells combined with mesenchymal stem cells for treatment of severe aplastic anemia in adult patients yields curative effects

BACKGROUND AIMS

Despite the great advances in immunosuppressive therapy for severe aplastic anemia (SAA), most patients are not completely cured. Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) has been recommended as an alternative treatment in adult SAA patients. However, haplo-HSCT presents a higher incidence of graft failure and graft-versus-host disease (GVHD). The authors designed a combination of haplo-HSCT and umbilical cord-derived mesenchymal stem cells (UC-MSCs) for treatment of SAA in adult patients and evaluated its effects.

METHODS

Adult patients (≥18 years) with SAA (N = 25) were given HLA-haploidentical hematopoietic stem cells (HSCs) combined with UC-MSCs after a conditioning regimen consisting of busulfan, cyclophosphamide, fludarabine and anti-thymocyte globulin and intensive GVHD prophylaxis, including cyclosporine, basiliximab, mycophenolate mofetil and short-term methotrexate. Additionally, the effects of the protocol in adult SSA patients were compared with those observed in juvenile SAA patients (N = 75).

RESULTS

All patients achieved myeloid engraftment after haplo-HSCT at a median of 16.12 days (range, 11-26). The median time of platelet engraftment was 28.30 days (range, 13-143). The cumulative incidence of grade II acute GVHD (aGVHD) at day +100 was 32.00 ± 0.91%. No one had grade III-IV aGVHD at day +100. The cumulative incidence of total chronic GVHD was 28.00 ± 0.85%. The overall survival was 71.78 ± 9.05% at a median follow-up of 42.08 months (range, 2.67-104). Promisingly, the protocol yielded a similar curative effect in both young and adult SAA patients.

CONCLUSIONS

The authors' data suggest that co-transplantation of HLA-haploidentical HSCs and UC-MSCs may provide an effective and safe treatment for adult SAA.

Invasive Fungal Diseases in Children with Hematological Malignancies Treated with Therapies That Target Cell Surface Antigens: Monoclonal Antibodies, Immune Checkpoint Inhibitors and CAR T-Cell Therapies

Since 1985 when the first agent targeting antigens on the surface of lymphocytes was approved (muromonab-CD3), a multitude of such therapies have been used in children with hematologic malignancies. A detailed literature review until January 2021 was conducted regarding pediatric patient populations treated with agents that target CD2 (alefacept), CD3 (bispecific T-cell engager [BiTE] blinatumomab), CD19 (denintuzumab mafodotin, B43, BiTEs blinatumomab and DT2219ARL, the immunotoxin combotox, and chimeric antigen receptor [CAR] T-cell therapies tisagenlecleucel and axicabtagene ciloleucel), CD20 (rituximab and biosimilars, 90Y-ibritumomab tiuxetan, ofatumumab, and obinutuzumab), CD22 (epratuzumab, inotuzumab ozogamicin, moxetumomab pasudotox, BiTE DT2219ARL, and the immunotoxin combotox), CD25 (basiliximab and inolimomab), CD30 (brentuximab vedotin and iratumumab), CD33 (gemtuzumab ozogamicin), CD38 (daratumumab and isatuximab), CD52 (alemtuzumab), CD66b (90Y-labelled BW 250/183), CD248 (ontuxizumab) and immune checkpoint inhibitors against CTLA-4 (CD152; abatacept, ipilimumab and tremelimumab) or with PD-1/PD-L1 blockade (CD279/CD274; atezolizumab, avelumab, camrelizumab, durvalumab, nivolumab and pembrolizumab). The aim of this narrative review is to describe treatment-related invasive fungal diseases (IFDs) of each category of agents. IFDs are very common in patients under blinatumomab, inotuzumab ozogamicin, basiliximab, gemtuzumab ozogamicin, alemtuzumab, and tisagenlecleucel and uncommon in patients treated with moxetumomab pasudotox, brentuximab vedotin, abatacept, ipilimumab, pembrolizumab and avelumab. Although this new era of precision medicine shows promising outcomes of targeted therapies in children with leukemia or lymphoma, the results of this review stress the necessity for ongoing surveillance and suggest the need for antifungal prophylaxis in cases where IFDs are very common complications.

Hepatic veno-occlusive disease/sinusoidal obstruction syndrome after hematopoietic stem cell transplantation for thalassemia major: incidence, management, and outcome

Hepatic veno-occlusive disease or sinusoidal obstruction syndrome (VOD/SOS) is a potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). In the present prospective study, we aimed to investigate the incidence, management, and outcome of VOD/SOS in patients with thalassemia major (TM) who received allo-HSCT. VOD/SOS was diagnosed and classified based on the modified Seattle criteria. The prophylactic regimen for VOD/SOS was a combination treatment of dalteparin and lipo-PGE1. VOD/SOS was managed through an approach consisting of adequate supportive measures, short-term withdrawal of calcineurin inhibitors (CNIs), and the use of methylprednisolone and basiliximab for graft-versus-host disease prophylaxis. VOD/SOS was found in 54 of 521 patients (10.4%) at a median time of 12 days after allo-HSCT. The cumulative incidence of all-grade and moderate VOD/SOS was 10.4% and 4.2%, respectively. Among the 54 VOD/SOS patients, no patient developed severe grade and died from VOD/SOS. Besides, the cumulative incidence of transplant-related mortality on day 100 for patients with or without VOD/SOS was 0% vs. 4.0% (P = 0.187), respectively, and the 3-year overall survival rates were 94.3% vs. 93.2% (P = 0.707), respectively. Collectively, we concluded that appropriate symptomatic therapy and short-term withdrawal of CNIs safely mitigated the mortality of VOD/SOS in TM patients who underwent allo-HSCT.

HLA-Haploidentical Family Donors: The New Promise for Childhood Acute Lymphoblastic Leukaemia?

Allogeneic haematopoietic stem cell transplantation (HSCT) is indicated in children with high-risk, relapsed or refractory acute lymphoblastic leukaemia (ALL). HLA-matched grafts from cord blood and stem cell repositories have allowed patients without suitable sibling donors to undergo HSCT. However, challenges in procuring matched unrelated donor (MUD) grafts due to high cost, ethnic disparity and time constraints have led to the exponential rise in the use of stem cells from human leukocyte antigen (HLA)-haploidentical family donors. Whilst HLA-haploidentical HSCT (hHSCT) performed in adult patients with acute leukaemia has produced outcomes similar to MUD transplants, experience in children is limited. Over the last 5 years, more data have emerged on hHSCT in the childhood ALL setting, allowing comparisons with matched donor transplants. The feasibility of hHSCT using adult family donors in childhood ALL may also address the ethical issues related to selection of minor siblings in matched sibling donor transplants. Here, we review hHSCT in paediatric recipients with ALL and highlight the emergence of hHSCT as a promising therapeutic option for patients lacking a suitable matched donor. Recent issues related to conditioning regimens, donor selection and graft-vs.-host disease prophylaxis are discussed. We also identify areas for future research to address transplant-related complications and improve post-transplant disease-free survival.

A study of human leukocyte antigen-haploidentical hematopoietic stem cells transplantation combined with allogenic mesenchymal stem cell infusion for treatment of severe aplastic anemia in pediatric and adolescent patients

The clinical applications of human leukocyte antigen (HLA) haploidentical hematopoietic stem cells transplantation (haplo‐HSCT) have offered most of the young severe aplastic anemia (SAA) patients an opportunity to accept curative therapy at the early stage of bone marrow lesions. However, the outcome of juvenile SAA patients received haplo‐HSCT remain to be improved due to high incidence of graft failure and graft vs host disease (GVHD). Mesenchymal stem cells (MSCs) have been characterized by their hematopoiesis‐supporting and immunomodulatory properties. In the current study, we designed a combination of haplo‐HSCT with allogenic MSC for treatment of SAA in pediatric and adolescent patients and evaluated its effects. Juvenile patients (<18 years) with SAA (n = 103) were given HLA‐haploidentical HSC combined with allogenic MSC after a conditioning regimen consisting of busulfan, cyclophosphamide, fludarabine, and antithymocyte globulin and an intensive GVHD prophylaxis, including cyclosporine, short‐term methotrexate, mycophenolate mofetil, and basiliximab. Neutrophil engraftment was achieved in 102 of 103 patients in a median time of 14.3 days (range 9‐25 days). The median time of platelet engraftment was 25.42 days (range 8‐93 days). The cumulative incidence of II‐IV acute GVHD at day +100 was 26.32% ± 0.19% and III‐IV acute GVHD was 6.79% ± 0.06% at day +100, respectively. The cumulative incidence of chronic GVHD was 25.56% ± 0.26%. The overall survival was 87.15% ± 3.3% at a median follow‐up of 40 (1.3‐98) months. Our data suggest that cotransplantation of HLA‐haploidentical HSC and allogenic mesenchymal stem cell may provide an effective and safe treatment for children and adolescents with SAA who lack matched donors.

Exploiting immunometabolism and T cell function for solid organ transplantation

Cellular metabolism is central to T cell function and proliferation, with most of the research to date focusing on cancer and autoimmunity. Cellular metabolism is associated with a host of physiological phenomena, from epigenetic changes, to cellular function and fate. For the purpose of this review, we will discuss the metabolism of T cells relating to their differentiation and function. We will cover a variety of metabolic processes, ranging from glycolysis to amino acid metabolism. Understanding how T cell metabolism informs T cell function may be useful to understand alloimmune responses and design novel therapies to improve graft outcome.

Prophylaxis and management of graft versus host disease after stem-cell transplantation for haematological malignancies: updated consensus recommendations of the European Society for Blood and Marrow Transplantation

Graft-versus-host disease (GVHD) is a major factor contributing to mortality and morbidity after allogeneic stem-cell transplantation. Because of the small number of results from well designed, large-scale, clinical studies there is considerable variability in the prevention and treatment of GVHD worldwide. In 2014, to standardise treatment approaches the European Society of Blood and Marrow Transplantation published recommendations on the management of GVHD in the setting of HLA-identical sibling or unrelated donor transplantation in adult patients with haematological malignancies. Here we update these recommendations including the results of study published after 2014. Evidence was searched in three steps: first, a widespread scan of published trials, meta-analyses, and systematic reviews; second, expert opinion was added for specific issues following several rounds of debate; and third, a refined search to target debated or rapidly updating issues. On the basis of this evidence and the 2014 recommendations, five members of the EBMT Transplant Complications Working Party created 38 statements on GVHD prophylaxis, drug management, and treatment of acute and chronic GVHD. Subsequently, they created the EBMT GVHD management recommendation expert panel by recruiting 20 experts with expertise in GVHD management. An email-based, two-round Delphi panel approach was used to manage the consensus. Modified National Comprehensive Cancer Network categories for evidence and consensus were applied to the approved statements. We reached 100% consensus for 29 recommendations and 95% consensus for nine recommendations. Key updates to these recommendations include a broader use of rabbit anti-T-cell globulin; lower steroid doses for the management of grade 2 acute GVHD with isolated skin or upper gastrointestinal tract manifestations; fluticasone, azithromycin, and montelukast should be used for bronchiolitis obliterans syndrome; and the addition of newer treatment options for resteroid-refractory acute and chronic GVHD. In addition, we discuss specific aspects of GVHD prophylaxis and management in the setting of haploidentical transplantation and in paediatric patients, but no formal recommendations on those procedures have been provided in this Review. The European Society of Blood and Marrow Transplantation proposes to use these recommendations as a basis for the routine management of GVHD during stem-cell transplantation.

The absolute number of regulatory T cells in unmanipulated peripheral blood grafts predicts the occurrence of acute graft-versus-host disease post haplo-identical hematopoietic stem cell transplantation

CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) have been reported to play a central role in suppressing acute graft-versus-host disease (aGVHD), but whether the Treg contents of grafts correlates with the occurrence of aGVHD post haplo-identical hematopoietic stem cell transplantation (haplo-HSCT) remains unclear. In the present study, changes in Tregs in peripheral blood (PB) were followed before and after granulocyte colony-stimulating factor (G-CSF) mobilization. In addition, functional analyses of Tregs in PB grafts and bone marrow (BM) grafts were performed. To probe the prognostic value of Tregs for aGVHD, an analysis of Tregs in haplo-identical grafts was conducted in 61 patients. Moreover, univariate and multivariate analyses of both clinical variables and cellular subsets were performed. The results showed that both the percentage Tregs of CD4⁺ T cells and absolute numbers of Tregs per 10⁶ total nucleated cells significantly increased after G-CSF administration. Additionally, Tregs in PB grafts exhibited a stronger inhibitory effect on antigen-specific T cell proliferation than did Tregs in BM grafts. Strikingly, patients receiving more Tregs in PB grafts had a lower cumulative incidence of aGVHD II-IV (36% versus 58%, P=0.046). Further, in a multivariate analysis, the number of Tregs in PB grafts was significantly associated with a lower occurrence of aGVHD II-IV (P=0.02). In contrast, the number of Tregs in BM grafts was not associated with the occurrence of aGVHD in the current study. Further analysis showed that the Treg content in grafts did not affect Treg reconstitution, infection rate, or incidence of chronic GVHD after haplo-HSCT. Moreover, no significant correlations between cell types in grafts and the survival end points or relapse rates were found in the present study. In conclusion, our results suggest that a high number of Tregs in PB grafts is associated with reduced risk of aGVHD in haplo-HSCT in our transplant setting.

HLA Haplotype Mismatch Transplants and Posttransplant Cyclophosphamide

The use of high dose posttransplant cyclophosphamide (PT-CY) introduced by the Baltimore group approximately 10 years ago has been rapidly adopted worldwide and is becoming a standard for patients undergoing unmanipulated haploidentical (HAPLO) transplants. PT-CY has been used following nonmyeloablative as well as myeloablative conditioning regimens, for bone marrow or peripheral blood grafts, for patients with malignant and nonmalignant disorders. Retrospective comparisons of HAPLO grafts with conventional sibling and unrelated donor grafts have been published and suggest comparable outcome. The current questions to be answered include the use of PT-CY for sibling and unrelated donors transplant, possibly in the context of prospective randomized trial.

Haploidentical, G-CSF-primed, unmanipulated bone marrow transplantation for patients with high-risk hematological malignancies: an update

Ninety-seven patients affected by high-risk hematological malignancies underwent G-CSF primed, unmanipulated bone marrow (BM) transplantation from a related, haploidentical donor. All patients were prepared with an identical conditioning regimen including Thiotepa, Busilvex, Fludarabine (TBF) and antithymocyte globulin given at myeloablative (MAC = 68) or reduced (reduced intensity conditioning (RIC) = 29) dose intensity and received the same GvHD prophylaxis consisting of the combination of methotrexate, cyclosporine, mycofenolate-mofetil and basiliximab. Patients were transplanted in 1st or 2nd CR (early phase: n = 60) or in > 2nd CR or active disease (advanced phase: n = 37). With a median time of 21 days (range 12-38 days), the cumulative incidence (CI) of neutrophil engraftment was 94 ± 3%. The 100-day CI of III-IV grade acute GvHD and the 2-year CI of extensive chronic GvHD were 9 ± 3% and 12 ± 4%, respectively. Overall, at a median follow-up of 2.2 years (range 0.3-5.6), 44 out of 97 (45%) patients are alive in CR. The 5-year probability of overall survival (OS) and disease-free survival (DFS) for patients in early and advanced phase was 53 ± 7 vs 24 ± 8% (P = 0.006) and 48 ± 7 vs 22 ± 8% (P = 0.01), respectively. By comparing MAC with RIC patient groups, the transplant-related mortality was equivalent (36 ± 6 vs 28 ± 9%) while the relapse risk was lower for the MAC patients (22 ± 6 vs 45 ± 11%), who showed higher OS (48 ± 7 vs 29 ± 10%) and DFS (43 ± 7 vs 26 ± 10%). However, all these differences did not reach a statistical significance. In multivariate analysis, diagnosis and recipient age were significant factors for OS and DFS. In conclusion, this analysis confirms, on a longer follow-up and higher number of patients, our previous encouraging results obtained by using MAC and RIC TBF regimen as conditioning for G-CSF primed, unmanipulated BM transplantation from related, haploidentical donor in patients with high-risk hematological malignancies, lacking an HLA-identical sibling or unrelated donor and in need to be urgently transplanted.

Modern approaches to HLA-haploidentical blood or marrow transplantation

Allogeneic blood or bone-marrow transplantation (alloBMT) is a potentially curative treatment for a variety of haematological malignancies and nonmalignant diseases. Historically, human leukocyte antigen (HLA)-matched siblings have been the preferred source of donor cells owing to superior outcomes compared with alloBMT using other donors. Although only approximately one-third of patients have an HLA-matched sibling, nearly all patients have HLA-haploidentical related donors. Early studies using HLA-haploidentical alloBMT resulted in unacceptably high rates of graft rejection and graft-versus-host disease (GVHD), leading to high nonrelapse mortality and consequently poor survival. Several novel approaches to HLA-haploidentical alloBMT have yielded encouraging results with high rates of successful engraftment, effective GVHD control and favourable outcomes. In fact, outcomes of several retrospective comparative studies seem similar to those seen using other allograft sources, including those of HLA-matched-sibling alloBMT. In this Review, we provide an overview of the three most-developed approaches to HLA-haploidentical alloBMT: T-cell depletion with 'megadose' CD34(+) cells; granulocyte colony-stimulating factor-primed allografts combined with intensive pharmacological immunosuppression, including antithymocyte globulin; and high-dose, post-transplantation cyclophosphamide. We review the preclinical and biological data supporting each approach, results from major clinical studies, and completed or ongoing clinical studies comparing these approaches with other alloBMT platforms.

Myeloablative haploidentical hematopoietic stem cell transplantation using basiliximab for graft-versus-host disease prophylaxis

OBJECTIVES

We retrospectively compared the prophylactic effect of basiliximab and antithymocyte globulin (ATG) after haploidentical hematopoietic stem cell transplantation (HSCT) in patients with leukemia.

METHODS

Haploidentical HSCT using basiliximab for graft-versus-host disease (GVHD) prophylaxis in 10 patients with leukemia was retrospectively compared to ATG for GVHD prophylaxis in 24 patients.

RESULTS

All the patients achieved neutrophil engraftment. One patient in the ATG group did not achieve platelet engraftment. The incidence of grade II-IV and grade III-IV acute GVHD was 30 and 20%, respectively, in the basiliximab group and 16.7 and 4.2%, respectively, in the ATG group (P > 0.05). Extensive cGVHD developed in 40 and 22.2% of patients in the basiliximab group and ATG group, respectively (P > 0.05). Basiliximab resulted in mild infection and a low incidence (10%) of infection-related mortality; ATG resulted in relative severe infection with 29.2% infection-related mortality (P > 0.05). During the follow-up period, 20% of the basiliximab group and 22.7% of the ATG group relapsed (P > 0.05). In the basiliximab group and the ATG group, the 3-year accumulative overall survival rate was, respectively, 80 and 52.5% and the 3-year leukemia-free survival, respectively, was 60 and 49.6% (P > 0.05).

DISCUSSION

The incidences of grade II-IV and grade III-IV aGVHD in the basiliximab group were similar to those in halpoidentical HSCT containing ATG. Compared to the ATG group, the basiliximab group had a lower rate of transplantation-related mortality and better long-term survival, but without statistical significance.

CONCLUSION

The prophylactic regimen of basiliximab with haploidentical HSCT against GVHD seems safe and promising. More studies needed to verify this.

Good outcome of haploidentical hematopoietic SCT as a salvage therapy in children and adolescents with acquired severe aplastic anemia

Haploidentical hematopoietic SCT (haplo-HSCT) is to be established in patients with acquired severe aplastic anemia (SAA) refractory to immunosuppressive therapy and lacking HLA-matched related or unrelated donors. Graft failure (GF) and GVHD have been major obstacles to HSCT. A total of 17 children and adolescents with SAA underwent haplo-HSCT in our center. The conditioning regimen consisted of BU, fludarabine, CY and anti-thymocyte globulin. All patients received cyclosporine, short-term MTX, mycophenolate mofetil and basiliximab for GVHD prophylaxis. Mesenchymal stem cells derived from unrelated umbilical cord were infused on day 1. Neutrophil engraftment was achieved in all 17 patients in a median time of 16 days (range 9-25 days). The median time of platelet engraftment was 22 days (range 9-95 days) in 16 patients. The cumulative incidence (CI) of II-IV acute GVHD (aGVHD) at day +100 was 30.53±11.12% and III-IV aGVHD occurred in only one patient. The CI of chronic GVHD was 21.25±13.31%. Secondary GF with autologous hematopoiesis recovery occurred in one patient. The OS was 71.60±17.00% at a median follow-up of 362 (36-1321) days. These limited promising data suggest that haplo-HSCT is feasible as a salvage therapy for children and adolescents with refractory SAA who lack matched donors.

Current and emerging strategies for the prevention of graft-versus-host disease

Graft-versus-host disease (GVHD) represents the most serious and challenging complication of allogeneic haematopoietic stem-cell transplantation (HSCT). New insights on the role of regulatory T-cells, T cells, and antigen-presenting cells have led to an improved understanding of the pathophysiology of GVHD. However, little progress has been made since the introduction of calcineurin-inhibitor-based regimens in the mid-1980s. Despite standard prophylaxis with these regimens, GVHD still develops in approximately 40-60% of recipients. Thus, there is a need for developing newer approaches to mitigate GVHD, which may facilitate the use of allogeneic HSCT for the treatment of a wider range of haematological cancers. We discuss the rationale, clinical evidence, and outcomes of current (and widely employed) strategies for GVHD prophylaxis, namely calcineurin-inhibitor-based regimens (such as cyclosporine or tacrolimus) combined with methotrexate or mycophenolate mofetil. We assess the clinical evidence for emerging approaches in the prevention of GVHD, including therapies targeting T cells or B cells, the use of mesenchymal stem cells, chemo-cytokine antagonists (such as maraviroc, TNF-α inhibitor, IL-2 receptor antagonist, IL-6 inhibitor), and the use of novel molecular regulators that target multiple cell types simultaneously, including atorvastatin, bortezomib, and epigenetic modulators.

Reduced intensity conditioning, combined transplantation of haploidentical hematopoietic stem cells and mesenchymal stem cells in patients with severe aplastic anemia

We examined if transplantation of combined haploidentical hematopoietic stem cells (HSC) and mesenchymal stem cells (MSC) affected graft failure and graft-versus-host disease (GVHD) in patients with severe aplastic anemia (SAA). Patients with SAA-I (N = 17) received haploidentical HSCT plus MSC infusion. Stem cell grafts used a combination of granulocyte colony-stimulating factor (G-CSF)-primed bone marrow and G-CSF-mobilized peripheral blood stem cells of haploidentical donors and the culture-expanded third-party donor-derived umbilical cord MSCs (UC-MSCs), respectively. Reduced intensity conditioning consisted of fludarabine (30 mg/m²·d)+cyclosphamide (500 mg/m²·d)+anti-human thymocyte IgG. Transplant recipients also received cyclosporin A, mycophenolatemofetil, and CD25 monoclonal antibody. A total of 16 patients achieved hematopoietic reconstitution. The median mononuclear cell and CD34 count was 9.3×10⁸/kg and 4.5×10⁶/kg. Median time to ANC was >0.5×10⁹/L and PLT count >20×10⁹/L were 12 and 14 days, respectively. Grade III-IV acute GVHD was seen in 23.5% of the cases, while moderate and severe chronic GVHD were seen in 14.2% of the cases. The 3-month and 6-month survival rates for all patients were 88.2% and 76.5%, respectively; mean survival time was 56.5 months. Combined transplantation of haploidentical HSCs and MSCs on SAA without an HLA-identical sibling donor was safe, effectively reduced the incidence of severe GVHD, and improved patient survival.

Granulocyte-mobilized bone marrow

PURPOSE OF REVIEW

In the last few years, mobilized peripheral blood has overcome bone marrow as a graft source, but, despite the evidence of a more rapid engraftment, the incidence of chronic graft-versus-host disease is significantly higher with, consequently, more transplant-related mortality on the long follow-up. Overall, the posttransplant outcome of mobilized peripheral blood recipients is similar to that of patients who are bone marrow grafted. More recently, the use of bone marrow after granulocyte colony-stimulating factor (G-CSF) donor priming has been introduced in the transplant practice. Herein, we review biological acquisitions and clinical results on the use of G-CSF-primed bone marrow as a source of hematopoietic stem cells (HSC) for allogeneic stem cell transplantation.

RECENT FINDINGS

G-CSF the increases the HSC compartment and exerts an intense immunoregulatory effect on marrow T-cells resulting in the shift from Th1 to Th2 phenotype with higher production of anti-inflammatory cytokines. The potential advantages of these biological effects have been translated in the clinical practice by using G-CSF primed unmanipulated bone marrow in the setting of transplant from human leukocyte antigen (HLA)-haploidentical donor with highly encouraging results.

SUMMARY

For patients lacking an HLA-identical sibling, the transplant of G-CSF primed unmanipulated bone marrow from a haploidentical donor combined with an intense in-vivo immunosuppression is a valid alternative achieving results that are well comparable with those reported for umbilical cord blood, HLA-matched unrelated peripheral blood/bone marrow or T-cell-depleted haploidentical transplant.

Haploidentical, unmanipulated, G-CSF-primed bone marrow transplantation for patients with high-risk hematologic malignancies

Eighty patients with high-risk hematologic malignancies underwent unmanipulated, G-CSF–primed BM transplantation from an haploidentical family donor. Patients were transplanted in first or second complete remission (CR, standard-risk: n =45) or in > second CR or active disease (high-risk: n =35). The same regimen for GVHD prophylaxis was used in all cases. The cumulative incidence (CI) of neutrophil engraftment was 93% 0.1%. The 100-day CIs for II-IV and III-IV grade of acute GVHD were 24% 0.2% and 5% 0.6%, respectively. The 2-year CI of extensive chronic GVHD was 6% 0.1%. The 1-year CI of treatment-related mortality was 36% 0.3%. After a median follow-up of 18 months, 36 of 80 (45%) patients are alive in CR. The 3-year probability of overall and disease-free survival for standard-risk and high-risk patients was 54% 8% and 33% 9% and 44% 8% and 30% 9%, respectively. In multivariate analysis, disease-free survival was significantly better for patients who had standard-risk disease and received transplantations after 2007. We conclude that unmanipulated, G-CSF–primed BM transplantation from haploidentical family donor provides very encouraging results in terms of engraftment rate, incidence of GVHD and survival and represents a feasible, valid alternative for patients with high-risk malignant hematologic diseases, lacking an HLA identical sibling and in need to be urgently transplanted.

KEY POINTS

Haploidentical, unmanipulated, G-CSF-primed bone marrow transplantation. Haploidentical hematopoietic stem cell transplantation for hematologic malignancies.

High frequency of CD4+ CD25- CD69+ T cells is correlated with a low risk of acute graft-versus-host disease in allotransplants

Regulatory T cells (Tregs) maintain transplantation tolerance and suppress graft-versus-host disease (GvHD) in humans. We monitored 17 subjects with acute GvHD to determine whether Treg frequency correlates with acute GvHD. We found the percent of CD4(+) CD25(-) CD69(+) Tregs decreases when acute GvHD develops and increases after acute GvHD is controlled. We next sequentially studied 50 subjects receiving conventional allotransplants. We show a high frequency and increased numbers of CD4(+) CD25(-) CD69(+) Tregs are associated with a reduced risk of acute GvHD. We also show that CD4(+) CD25(-) CD69(+) Treg numbers increase substantially early after allografts and that a low percent of CD4(+) CD25(-) CD69(+) Tregs is associated with an increased risk of acute GvHD. Reconstitution of Tregs early post-transplant is associated with less acute GvHD. These data imply that CD4(+) CD25(-) CD69(+) Tregs are a novel subset of regulatory T cells that may protect against acute GvHD after allotransplants.

Cotransplantation of allogeneic mesenchymal and hematopoietic stem cells in children with aplastic anemia

We report here the preliminary results of allogeneic hematopoietic stem cell transplantation with mesenchymal stem cells (MSCs) for 6 cases of severe aplastic anemia. The patients ranged in age from 3 to 16 years, and the median time from diagnosis to transplantation was 32 months (range: 3-156 months). The conditioning regimens consisted of fludarabine, cyclophosphamide, and antithymocyte globulin with or without busulfan. Graft-versus-host disease (GvHD) was prevented by the administration of cyclosporine A, methotrexate, and mycophenolate mofetil, with or without anti-CD25 monoclonal antibody. The grafts were granulocyte colony-stimulating factor-mobilized bone marrow and peripheral blood from HLA antigen-haploidentical donors (3 cases) or peripheral blood only from unrelated HLA antigen-identical donors (3 cases). MSCs were intravenously injected at a median dose of 1.43 × 10(6)/kg (range: 0.85-2.5 × 10(6)/kg). The mean time for neutrophil and platelet recovery was 12.3 and 13.8 days, respectively. Acute GvHD grade I and II developed in 2 cases, and no chronic GvHD was documented. All patients were alive and transfusion independent at a median follow-up of 15 months (range: 6-29 months). Our report suggests that cotransplantation of allogeneic hematopoietic stem cells and MSCs might provide an opportunity for therapy for children with severe aplastic anemia.

Haploidentical hematopoietic stem cell transplantation in hematologic malignancies with G-CSF mobilized bone marrow plus peripheral blood stem cells grafts without T cell depletion: a single center report of 29 cases

Haploidentical Hematopoietic stem cell transplantation (Haplo-HSCT) has provided an alternative option since virtually all patients have an immediately available donor. Here, we report the results of Haplo-HSCT with granulocyte-colony-stimulating factor (G-CSF) mobilized bone marrow grafts plus peripheral blood stem cells as the grafts without T-cell depletion. Twenty-nine patients with the mean age of 27.27 years (ranging from 15 to 51 years) were enrolled in this study, and 10 cases were in high risk status. The patients received myeloablative preconditioning with or without total body irradiation and acute graft-versus-host disease (GVHD) prophylaxis consisting of basiliximab, cyclosporine A, methotrexate, mycophenolate mofetil and a rabbit anti-thymocyte globulin. All the patients attained successful neutrophil and platelet recovery. The mean times for neutrophil and platelet recovery were 17.1 and 20.9 days, respectively. During the follow-up at a median time of 30.69 months (ranging from 3 to 76 months), nine patients developed aGVHD grade II-IV, including two developed grade III-IV GVHD after donor lymphocyte infusion. The incidence of cGVHD was 48.3%. 13 patients died within the first two years after transplantation, and the total disease-free survival rate longer than 2 years was 55.2%. These results suggest that G-CSF-primed bone marrow plus peripheral blood stem cell grafts are an appropriate stem cell source for Haplo-HSCT and large scale investigations are needed to confirm this protocol.

Haploidentical hematopoietic stem-cell transplantation for non-Hodgkin lymphoma with bone marrow involvement

Here, we report the preliminary results of haploidentical hematopoietic stem cell transplantation (Haplo-HSCT) with granulocyte-colony-stimulating factor (G-CSF) mobilized bone marrow grafts without T-cell depletion for 10 patients with refractory non-Hodgkin lymphoma accompanied by bone marrow involvement. Eight patients received a conditioning regimen consisting of high-doses of cytarabine and cyclophosphamide with total body irradiation, whereas two cases were preconditioned with busulfan, thiotepa, and cyclophosphamide. All patients had rapid hematopoietic engraftment with the mean time for neutrophil and platelet recovery being 16.6 days and 19.2 days, respectively. Three cases died within 6 months after transplantation from severe acute graft-versus-host disease, fungal infection, or relapse. The others are currently alive in complete remission at a median follow-up of 60.71 months (range: 44-81 months). The results here suggest that haplo-HSCT might provide an opportunity of myeloablative therapy for refractory lymphoma with marrow infiltration.

Mesenchymal stem cells of cord blood origin are effective at preventing but not treating graft-versus-host disease

The immunosuppressive properties of mesenchymal stem cells (MSC) make them particularly attractive to manipulate graft-versus-host disease (GVHD). So far, the experience of using MSC to treat GVHD is limited to a few cases, controversial results come from preclinical models and several issues remain to be clarified. The present studies were designed to address these questions in a xenogenic model testing the ability of umbilical cord blood-derived MSC (UCB-MSC) to prevent and/or treat GVHD. Sublethally irradiatiated non-obese diabetic/severe combined immunodeficiency NOD/SCID mice transplanted with human peripheral blood mononuclear cells (huPBMC) showed extensive human T-cell proliferation in the peripheral blood, lymphoid and non-lymphoid tissues, which evolved in extensive GVHD (wasting, ruffled hair and hunched back). The mice treated with a single dose of UCB-MSC did not behave differently form the controls. However, when UCB-MSC were given at weekly intervals, there was a marked decrease in human T-cell proliferation and none of the mice developed GVHD. No therapeutic effect was obtained if UCB-MSC were administered at onset of GVHD. This work supports the clinical use of MSC in stem cell transplantation as a prophylaxis rather than treatment of GVHD.

Impact of vaccine therapy using nuclear histone H1 on allograft survival in experimental organ transplantation

BACKGROUND

We recently reported that autoreactive antibody (Ab) against nuclear histone H1 had been identified as an immunosuppressive factor in a rat tolerogenic orthotopic liver transplantation (OLT) model. The present study aimed to determine whether the up-regulation of antihistone H1 Ab by histone H1 vaccination leads to tolerance.

METHODS

Histone H1-immunized rats were established by intraperitoneal vaccination with histone H1 at every two-weekly interval. By using mixed lymphocyte reaction (MLR) and heterotopic heart transplantation (HHT), the alloreactive T cell response and allograft survival of histone H1-immunized rats were compared with those of control rats. Cytokine and cellular profiles in histone H1-immunized rats were determined by reverse transcriptase polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA) and flow cytometry.

RESULTS

Immunization with histone H1 in Freund's adjuvant induced alloreactive T cell unresponsiveness and prolonged heterotopic heart allograft survival. It also down-regulated the expression of major histocompatibility complex (MHC) class II and CD25 on splenic cells, elevated the T helper cell type 2 (Th2) skewing index (Interleukin (IL)-4/interferon (IFN)-gamma ratio or IL-4/IL-2 ratio) and modified the serum cytokine profiles.

CONCLUSIONS

The present results suggest that histone H1 vaccination of transplant recipients, which leads to the production of immunosuppressive factor and the modification of the cytokine/cellular profiles, has great potential as a tolerance therapy for prospective transplantation.

NK026680, a novel compound suppressive of dendritic cell function, ameliorates mortality in acute lethal graft-versus-host reaction in mice

A role for dendritic cells (DCs) has been emphasized in the onset of acute graft-versus-host disease (GVHD). We have made efforts to develop a new strategy for suppression of DC functions with a chemical compound in the treatment of acute GVHD. We here describe the immunological characterization of the new chemical compound NK026680. It was found that NK026680 significantly suppressed (1) expression of CD83, CD86, and major histocompatibility complex (MHC) class I and II antigens on human monocyte-derived DCs, (2) excretion of interleukin-12p40 on activation of monocyte-derived DCs, (3) allogeneic responses of human and mouse T cells and (4) mortality in mice with acute GVHD evoked across MHC class I or II. The beneficial effect of NK026680 administered orally was without any recognizable adverse effects. Early intervention in acute GVHD was required for this effect, indicating that an early event in acute GVHD is a critical target of NK026680. We propose the use of NK026680 as a prophylactic for acute GVHD.