Current status of haploidentical stem cell transplantation for leukemia

HLA-mismatched allogeneic adoptive immune therapy in patients with severely immunosuppressed AIDS: a multicenter, open-label, controlled, phase 2a study

Recurrent opportunistic infections (OIs) in patients with severely immunosuppressed AIDS remain an unresolved medical challenge despite advancements in antiretroviral therapy (ART). To address this gap, we developed an HLA-mismatched allogeneic adoptive immune therapy (AAIT) specifically targeting this patient population. The safety and efficacy of this novel therapeutic approach were preliminarily confirmed in our phase 1 trial. Subsequently, a multicenter, open-label, controlled, phase 2a trial was conducted to evaluate the efficacy of AAIT in combination with ART compared with the conventional ART-only regimen. No difference in the incidence of adverse events (AEs) was observed between the two groups at the 96-week follow-up. AAIT treatment improved CD4+ T cell recovery at weeks 72 (P = 0.048) and 96 (P = 0.024) compared to the Control Group. Additionally, stratified analysis of patients in the AAIT Group showed that donor/recipient sex mismatch was significantly associated with the likelihood of patients achieving an immunological response (OR = 8.667; 95% CI, 2.010-37.377; P = 0.004). These findings suggest that AAIT serves as a promising adjunct therapy for improving the outcomes of patients with severely immunosuppressed AIDS. Further studies are needed to elucidate the immunological mechanisms underlying AAIT and identify the subpopulations that respond optimally to this therapeutic approach. This trial is registered at www.clinicaltrials.gov (NCT04098770).Trial registration: ClinicalTrials.gov identifier: NCT04098770.Trial registration: ClinicalTrials.gov identifier: NCT02651376.

Cytomegalovirus infection is associated with rapid NK differentiation and reduced incidence of relapse in HLA matched sibling donor transplant patients

The effect of cytomegalovirus (CMV) infection on leukemia relapse and the potential mechanism remains controversial. In this retrospective study, we evaluated the association among CMV infection, NK reconstitution and clinical outcomes in consecutive patients with hematologic malignancy who underwent HLA matched sibling donor transplantation (MST). In total, 228 patients were enrolled in the study between January 2010 and December 2011. The cumulative incidence of CMV infection on day 100 post-HSCT was 13.6 ± 4.9%. The probabilities of OS and DFS were 45.4% vs. 71.7% (P = 0.004) and 43.9% vs. 64.2% (P = 0.050) in the patients with CMV infection and without CMV infection, respectively. The cumulative incidence of treatment-related mortality (TRM) and relapse at 5 years was 48.6 ± 9.6% vs. 11.5 ± 2.9% (P < 0.001) and 6.2 ± 4.3% vs. 29.2 ± 3.9% (P = 0.024) in the patients with CMV infection and without CMV infection, respectively. In the multivariate analysis, CMV infection was associated with higher TRM, lower OS, and lower DFS. In addition, we found that CMV infection may promote the recovery of the absolute number of NK cells and promote the differentiation of NK cells post-MST. In conclusion, CMV infection may promote the recovery and differentiation of NK cells and was correlated with a lower relapse rate post-MST.

Oral eltrombopag versus subcutaneous recombinant human thrombopoietin for promoting platelet engraftment after allogeneic stem cell transplantation: A prospective, non-inferiority, randomized controlled trial

Delayed platelet engraftment (DPE) is associated with poor survival and increased transplantation-related mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Therefore, treatments are needed to improve platelet engraftment and prevent DPE. We performed a phase three, non-inferior, randomized controlled study of eltrombopag or recombinant human thrombopoietin (rhTPO) to promot platelet engraftment after allo-HSCT. Candidates for allo-HSCT were randomly assigned to receive oral eltrombopag (50 mg daily) or subcutaneous rhTPO (15000U daily) from the first-day post-transplantation. The primary endpoint was the cumulative numbers of platelet engraftment (platelet recovery ≥20 × 10⁹ /L, without transfusion, for seven consecutive days) on day 60 after transplantation. We performed intention-to-treat analyses with a non-inferior margin of -15%. A total of 92 participants underwent randomization. 44 and 48 patients were randomized to the eltrombopag and rhTPO groups, respectively. The median duration of follow-up was 360 days (range: 12-960 days). The cumulative incidence of platelet engraftment on day 60 after transplantation in eltrombopag group was 86.4% (38/44) compared with 85.4% (41/48) in the rhTPO group (absolute risk difference [ARD] 1%, one-sided lower limit of 95% confidence interval [CI] -13.28%, P_{non-inferirioty}  = 0.014). The rate of DPE in the eltrombopag group was 6.8% (3/44) compared with 12.5% (6/48) in the rhTPO group (ARD -5.7%, one-sided higher limit of 95% CI 6.28%, P_{non-inferirioty}  = 0.063). Approximately, three-fourths of non-hematologic adverse events were not observed in the eltrombopag group but three patients (3/48, 6%) experienecd them in the rhTPO group. In addition, platelet transfusions unite from day 0 to day 21, or from day 22 to day 60, progression-free survival, overall survival were not significantly different between both groups. Eltrombopag was non-inferior to rhTPO in promoting platelet engraftment post allo-HSCT for patients with hematological malignancy. Oral eltrombopag was more convenient for patients than subcutaneous rhTPO (NCT03515096).

Human herpesvirus 6 reactivation in unmanipulated haploidentical hematopoietic stem cell transplantation predicts the occurrence of grade II to IV acute graft-versus-host disease

BACKGROUND

Human herpesvirus 6 (HHV-6) reactivation is relatively common after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the incidence of HHV-6 reactivation and the clinical outcomes following unmanipulated haploidentical HSCT (haplo-HSCT) remain unknown.

METHOD

We prospectively monitored blood HHV-6 DNA using real-time quantitative polymerase chain reaction weekly until day 100 post unmanipulated haplo-HSCT in patients with hematological malignancies.

RESULTS

From November 2016 to March 2017, 102 patients (58 male and 44 female, median age 25(2-58) years old) were enrolled. Within 100 days post-transplantation, 27 patients (27/136, 19.9%) developed HHV-6 viremia with a median onset time of 14 (7-98) days. The cumulative incidence of HHV-6 reactivation on day 100 post-HSCT was 25.5 ± 4.3% in haplo-HSCT. The median HHV-6 copy number was 1.45 × 10³ (5.48 × 10² -2.00 × 10⁴ ) copies/ml. The HHV-6 viremia duration time was 7 days in 23 patients, 14 days in one patient and 21 days in one patient. In multivariate analysis, prior HHV-6 reactivation was an independent risk factor for grade 2-4 graft-versus-host disease (GVHD). But it did not influence the overall survival (OS)(HR 1.624, 95%CI 0.768-3.432, P = .204), disease-free survival (DFS) (HR 1.640, 95%CI 0.799-3.367, P = .177) and non-relapse mortality (NRM) (HR 1.644, 95%CI 0.670-4.038, P = .278).

CONCLUSION

The reactivation of HHV-6 after unmanipulated haploidentical transplantation predicts the occurrence of grade 2-4 a-GVHD, but it may not influence the overall survival (OS), disease-free survival (DFS) and non-relapse mortality (NRM).

Advances in preclinical hematopoietic stem cell models and possible implications for improving therapeutic transplantation

Hematopoietic stem cell transplantation (HSCT) is a treatment for many malignant, congenital, and acquired hematologic diseases. Some outstanding challenges in the HSCT field include the paucity of immunologically‐matched donors, our inability to effectively expand hematopoeitic stem cells (HSCs) ex vivo, and the high infection risk during engraftment. Scientists are striving to develop protocols to generate, expand, and maintain HSCs ex vivo, however these are not yet ready for clinical application. Given these problems, advancing our understanding of HSC specification, regulation, and differentiation in preclinical models is essential to improve the therapeutic utility of HSCT. In this review, we link biomedical researchers and transplantation clinicians by discussing the potential therapeutic implications of recent fundamental HSC research in model organisms. We consider deficiencies in current HSCT practice, such as problems achieving adequate cell dose for successful and rapid engraftment, immense inflammatory cascade activation after myeloablation, and graft‐vs‐host disease. Furthermore, we discuss recent advances in the field of HSC biology and transplantation made in preclinical models of zebrafish, mouse, and nonhuman primates that could inform emerging practice for clinical application.

Autoimmune hemolytic anemia after allogeneic hematopoietic stem cell transplantation in adults: A southern China multicenter experience

To investigate the incidence and risk factors as well as prognosis of autoimmune hemolytic anemia (AIHA) following allogeneic hematopoietic stem cell transplantation (allo‐HSCT), a total of 1377 adult hematological malignancies at three institutions were enrolled in this study. The 3‐year cumulative incidence of AIHA was 2.2 ± 0.4%. Multivariate analysis showed that haploidentical donors (HRDs) and chronic graft vs host disease (cGVHD) were the independent risk factors for AIHA. Patients with AIHA treated initially with corticosteroids combined with cyclosporine A (CsA) had a higher complete response rate than those with corticosteroids monotherapy (66.7% vs 11.1%; P = .013). The 3‐year cumulative incidence of malignant diseases relapse was 4.4 ± 4.3% and 28.0 ± 1.3% (P = .013), treatment‐related mortality (TRM) was 8.9 ± 6.3% and 17.4 ± 1.2% (P = .431), disease‐free survival (DFS) was 56.1 ± 1.5% and 86.7 ± 7.2% (P = .011), and overall survival (OS) was 86.3 ± 7.4% and 64.1 ± 1.5% (P = .054), respectively, in the patients with AIHA and those without AIHA. Our results indicate that HRDs and cGVHD are risk factors for AIHA and corticosteroids combined with CsA are superior to corticosteroids as initial treatment for AIHA. Autoimmune hemolytic anemia does not contribute to increase TRM and could reduce the malignant diseases relapse and increase DFS.

Prognostic values of increased B7 family proteins in haploidentical hematopoietic stem cell transplantation patients with aGVHD

It has been reported that B7H1 and B7H3 play a role in graft-versus-host disease (GVHD), the major cause of treatment-related mortality (TRM) in haploidentical hematopoietic stem cell transplantation (haplo-HSCT) patients; however, the prognostic value of these factors has not been defined. We retrospectively collected 64 haplo-HSCT patients in our hospital from 2013 to 2014, as well as 38 HLA-matched-HSCT patients during the same period as the control group. We analyzed B7H1, B7H3, PD1, soluble CD25, ST2 and TNFR1 at 0 day, + 7 days, + 14 days and + 28 days after HSCT. The + 7 days/+ 14 days B7H1/B7H3 and + 28 days ST2 serum levels were higher in patients with aGVHD who underwent haplo-HSCT. Moreover, + 7 days B7H1/B7H3 serum levels were predictive of grade III-IV aGVHD (B7H1: AUC = 0.830, P < 0.001; B7H3: AUC = 0.775, P = 0.001). Haplo-HSCT patients with higher + 7 days B7H1/B7H3 or + 28 days ST2 serum levels had poor GVHD-related mortality (GRM) (B7H1: P < 0.001; B7H3: P = 0.002; ST2: P = 0.047). Multivariate analysis revealed that the + 7 days B7H1 serum level (P = 0.041), as well as viral infection (P = 0.015) and donor age (P = 0.012), could independently predict GRM. Collectively, we found that + 7 days B7H1/B7H3 serum levels can predict grade III-IV aGVHD, while only the + 7 days B7H1 serum level, together with viral infection and donor age, could independently predict GRM in patients with haplo-HSCT.

Autoimmune hematological diseases following haploidentical donor hematopoietic stem cell Transplant compared with matched sibling and unrelated donor

Autoimmune hematological diseases (AHDs) occur more frequently than other autoimmune complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and are often refractory to treatment. This study was to analyze the incidence and risk factors of AHDs as well as their response to treatment. Four hundred and forty-five adult malignant hematopoietic disorders underwent allo-HSCT were enrolled in this retrospective study, including 124 haploidentical donor (HRD), 140 unrelated donor (MUD) and 181 HLA-matched sibling donor (MSD) transplants. Twelve patients developed AHDs, including 6 autoimmune hemolytic anemia and 6 Evans syndrome. Evans syndrome all occurred in HRD transplants. The 3-year cumulative incidence of AHDs was 4.0 ± 1.3%, and HRD had higher incidence than MUD (8.7 ± 3.0% vs 1.8 ± 1.2%, P = 0.012) and MSD (8.7 ± 3.0% vs 3.5 ± 2.6%, P = 0.004 ). The steroids combined with Cyclosporine A were acted as the first line treatment, and the response rate was 73%. No patients experienced recurrence at a median follow up of 313 days after stopping treatment. HRD transplants (vs MUD: HR, 5.87; CI, 1.24 to 27.73; ^p = 0.026 and vs MSD: HR, 7.70; CI, 1.63 to 36.44; P = 0.010) and concurrent chronic graft versus host disease (HR, 3.76; CI, 1.18 to 11.92; P = 0.025) were risk factors for AHDs.

Optimal donor for severe aplastic anemia patient requiring allogeneic hematopoietic stem cell transplantation: A large-sample study from China

HLA-haploidentical hematopoietic stem cell transplantation (HSCT) may be an option for severe aplastic anemia (SAA) patients. However, to date, no large-sample studies have been performed to determine which types of SAA patients are suitable for HLA-haploidentical HSCT. We retrospectively studied 189 consecutive patients with SAA who underwent HLA-identical or HLA-haploidentical HSCT at seven transplant centers in China. Propensity score matching (PSM) was applied in this study to reduce the influence of potential confounders. The 5-year overall survival (OS) rate was 72.0% in the HLA-haploidentical group and 76.5% in the HLA-identical group. The median time to achieve engraftment and the incidence of acute GVHD/chronic GVHD were not significantly different between the two groups. In the subgroup analysis, the outcome of patients older than 40 years in the HLA-haploidentical group was significantly poorer than that of patients younger than 40 years in the same group and that of patients older than 40 years in the HLA-identical group. Based on the above results, we suggest that HLA-haploidentical relative HSCT should be considered as a valid alternative option for patients younger than 40 years with SAA for whom no matched sibling donor is available.

Risk factors in patients undergoing haploidentical hematopoietic stem cell transplantation for high-risk childhood acute leukemia

In the present study, we sought to analyze the risk factors following haploidentical hematopoietic stem cell transplantation (haplo-HSCT) in children with high-risk acute leukemia. We retrospectively reviewed data from 73 children with high-risk leukemia. Univariate and multivariate analyses were performed to evaluate relationships between variables and patient outcomes. The mean time for neutrophil engraftment was significantly shorter in children given a graft with a higher number of nucleated cells (>10.13 × 108/kg vs ≤10.13 × 108/kg: 13.79 ± 2.73 vs 17.71 ± 3.90 days, P < 0.001) and in younger children (≤10 years vs >10 years: 14.21 ± 3.12 vs 17.71 ± 3.90 days, P < 0.001). Time to platelet engraftment was clearly shorter in children given a graft with higher number of nucleated cells (>10.13 × 108/kg vs ≤10.13 × 108/kg: 12.12 ± 8.62 vs 32.1 ± 24.83 days, P < 0.028). Overall survival was 64.6 ± 9.1%, 41.1 ± 10.1%, and 81.6 ± 9.6%, respectively, in children with HR-ALL in CR1, ALL in CR2-4, and AML (P = 0.012). The number of total nucleated cells was significantly associated with transplant-related mortality (TRM). We suggest that outcomes of haplo-HSCT may be improved by increased infusion of nucleated cells.

Low incidence of acute graft-versus-host disease with short-term tacrolimus in haploidentical hematopoietic stem cell transplantation

Although tacrolimus (Tac) has immunosuppressive properties and exhibits promising efficacy against graft-versus-host disease (GVHD), little is known about Tac in the prophylaxis of GVHD after HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT). In a multicenter randomized controlled trial, 174 patients received haplo-HSCT with GVHD prophylaxis involving short-term Tac (from -8days to +30days) or cyclosporine (CsA). The 100day cumulative incidences of acute GVHD (aGVHD) and grade III-IV aGVHD with the short-term Tac regimen and CsA regimen were 29.1 (19.5-38.7)% vs. 50.0(39.6-60.4)% (p=0.005) and 3.6(0.0-7.5)% vs. 13.5(6.1-20.9)% (p=0.027), respectively. There were no significant differences in the incidences of chronic GVHD (cGVHD), relapse and cytomegalovirus infection. Lymphocyte subset analysis showed that T cells decreased to lower levels on the short-term Tac regimen within 3 months of transplantation. The disease-free survival and overall survival on the short-term Tac and CsA regimens were 59.3 (48.9-69.7)% vs. 55.7 (45.3-66.1)% (p=0.696) and 65.1 (55.1-75.1)% vs. 61.4 (51.2-71.6)% (p=0.075), respectively. Our findings indicate that the short-term Tac regimen for GVHD prophylaxis in patients undergoing haplo-HSCT is associated with a low incidence and slight severity of aGVHD and did not increase the incidence of relapse and cytomegalovirus infection.

Haploidentical peripheral blood stem cell transplantation with posttransplant cyclophosphamide in children and adolescents with hematological malignancies

BACKGROUND

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) using posttransplant cyclophosphamide (Cy) for graft versus host disease (GVHD) prophylaxis has emerged as an alternative transplant strategy for patients without related donors, especially in the setting of limited resources in which T-cell ex vivo depletion is not affordable. Experience with this transplant modality in children and adolescents is limited.

PROCEDURE

We report a retrospective analysis of 25 consecutive outpatients under 21 years of age with high-risk hematological malignancies, who received a haplo-HSCT using posttransplant Cy as GVHD prophylaxis.

RESULTS

Twenty-three (92%) of the 25 patients engrafted, and 20 (95%) of 21 evaluable subjects achieved full donor chimerism by day +30. One-year estimated overall survival and event-free survival were 50% and 33%, respectively. The cumulative incidence rate of severe acute GVHD was 19%, and 15% of patients developed chronic GVHD.

CONCLUSIONS

Haplo-HSCT with posttransplant Cy is a feasible therapeutic option for children and adolescents with high-risk hematological malignancies in a limited resource setting.

Antifungal prophylaxis of patients undergoing allogenetic hematopoietic stem cell transplantation in China: a multicenter prospective observational study

Background

Antifungal prophylaxis is currently regarded as the gold standard in situations with allo-genetic hematopoietic stem cell transplantation (allo-HSCT). However, the epidemiological information regarding prophylaxis of invasive fungal diseases (IFDs) is not clear in China.

Methods

We report the first large-scale (1053 patients) observational study of the prophylaxis and management of IFDs among patients with allo-HSCT in China.

Results

The incidence rates of IFD after primary antifungal prophylaxis (PAP), secondary antifungal prophylaxis (SAP), and non-prophylaxis were 22.7 vs. 38.6 vs. 68.6 %, respectively (P = 0.0000). The median time from transplantation to IFD was 45 days in PAP patients, 18 days in SAP patients, and 12 days in non-prophylaxis patients. Aspergillus spp. represents the most common type of fungal infection. Independent risk factors for IFD in allo-HSCT patients with PAP were age, having human leukocyte antigen (HLA)-haploidentical or matched unrelated donor, decreased albumin levels, and the use of itraconazole as the prophylactic antifungal agent. Among SAP transplant recipients, there was no significant risk factor for IFDs. The incidence rates of overall survival (OS) in the PAP, SAP, and no prophylaxis groups were 85.07, 78.80, and 74.82, respectively (P = 0.01).

Conclusions

This observational study indicates that prophylaxis of IFD is helpful to reduce the incidence of IFDs and improve the OS of patients after allo-HSCT.

Clinical characteristics and risk factors of Intracranial hemorrhage in patients following allogeneic hematopoietic stem cell transplantation

Intracranial hemorrhage (ICH) is one of the most life-threatening neurological complications after allogeneic hematopoietic stem cell transplantation. Although cerebral complications and its causes after allo-HSCT are well documented, assessment of the incidence and risk factors of intracranial hemorrhage following allo-HSCT are less discussed. A nested case-control study was conducted involving 160 subjects drawn from 2169 subjects who underwent HSCT at Peking University People's Hospital between 2004 and 2014. Thirty-two patients (1.5 %) with ICH were identified, and 128 controls were matched for age, gender, transplantation type, and time of transplantation. Intracranial hemorrhage was identified by CT scan and/or MRI by searching hospital records. Among the 32 ICH patients, 27 (82.9 %) developed intraparenchymal hemorrhages (IPH), 2 cases (5.7 %) suffered subdural hematomas (SDH), and 3 cases (8.6 %) had multiple hemorrhage lesions in the brain parenchyma. The median time of appearance for cerebral hemorrhages was 147.5 days. Multivariate analysis showed that systemic infections (hazard ratio 2.882, 95 % confidence interval 1.231-6.746), platelet count (5.894, 1.145-30.339), and fibrinogen levels (3.611, 1.528-8.532) were independent risk factors for intracranial hemorrhage among HSCT patients. The cumulative survival rate in the intracranial hemorrhage and control groups were 43.3 and 74.7 % (P = .001), respectively. Intracranial hemorrhage is associated with high mortality and a decreased overall survival rate. Systemic infections, platelet count, and fibrinogen levels were individual independent risk factors.

Advances and perspectives on cellular therapy in acquired bone marrow failure diseases

Acquired bone marrow failure diseases (ABMFD) are a class of hematopoietic stem cell diseases with a commonality of non-inherited disruption of hematopoiesis that results in pancytopenia. ABMFDs also are a group of heterogeneous diseases with different etiologies and treatment options. The three most common ABMFDs are aplastic anemia, myelodysplastic syndrome, and paroxysmal nocturnal hemoglobinuria. Stem cell transplantation is the only treatment that can cure these diseases. However, due to high therapy-related mortality, stem cell transplantation has rarely been used as a first line treatment in treating ABMFD. With the advance of personalized medicine and precision medicine, various novel cellular therapy strategies are in trial to increase the efficiency and efficacy of ABMFD treatment. This article aims to review current available stem cell transplantation protocols and promising cellular therapy research in treating ABMFD.

An overview of conditioning regimens for haploidentical stem cell transplantation with post-transplantation cyclophosphamide

Haploidentical related donors are an attractive alternative source of stem cells for allogeneic stem cell transplantation due to widespread availability and ease of stem cell procurement. Historically, haploidentical stem cell transplantation (HaploSCT) with extensive T-cell depletion has been associated with high rates of infectious complications and nonrelapse mortality (NRM). Post-transplantation cyclophosphamide (PTCy) has been shown to induce immune tolerance, effectively control graft-versus-host-disease (GVHD), and is associated with lower NRM, making it a preferred option for patients undergoing HaploSCT. Over the last decade, several groups investigated PTCy for GVHD prevention in HaploSCT; it is now successfully utilized with both myeloablative and nonmyeloablative conditioning regimens with survival comparable to HLA-matched transplantation. Future directions will focus on optimizing conditioning regimens by diagnosis, improving donor selection, and enhancing graft-versus-leukemia effect.

Haploidentical stem cell transplantation augmented by CD45RA negative lymphocytes provides rapid engraftment and excellent tolerability

BACKGROUND

Haploidentical donors are being increasingly used for allogeneic hematopoietic cell transplantation (HCT). However, the requisite T-cell depletion results in a profound and often long-lasting immunocompromised state, and donor lymphocyte infusions bring a risk of graft-versus-host disease (GVHD). Naïve T-cells are believed to be among the most alloreactive T-cell subset and can be identified by CD45RA expression. Allogeneic HCT using CD45RA depletion has not been previously described for haploidentical donors.

PROCEDURE

Eight children with relapsed or refractory solid tumors were transplanted following myeloablative conditioning. Each patient received two cell products, one created by CD3 depletion and the other through CD45RA depletion.

RESULTS

Median CD34 recovery was 59.2% with CD45RA depletion, compared to 82.4% using CD3 depletion. Median CD3+ T-cell dose after CD45RA reduction was 99.2 × 10(6)  cells/kg, yet depletion of CD3+ CD45RA+ cells exceeded 4.5 log. CD45RA depletion also resulted in substantial depletion of B-cells (median 2.45 log). All eight patients engrafted within 14 days and rapidly achieved 100% donor chimerism. No acute GVHD or secondary graft failure was observed.

CONCLUSIONS

CD45RA depletion is a novel approach to haploidentical HCT that offers rapid engraftment with minimal risk of GVHD.

Prophylaxis and treatment of acute lymphoblastic leukemia relapse after allogeneic hematopoietic stem cell transplantation

Relapse of acute lymphoblastic leukemia remains a major cause of death in patients following allogeneic hematopoietic stem cell transplantation. Several factors may affect the concurrence and outcome of relapse, which include graft-versus-host disease, minimal residual disease or intrinsic factors of the disease, and transplantation characteristics. The mainstay of relapse prevention and treatment is donor leukocyte infusions, targeted therapies, second transplantation, and other novel therapies. In this review, we mainly focus on addressing the impact of graft-versus-host disease on relapse and the prophylaxis and treatment of acute lymphoblastic leukemia relapse following allogeneic hematopoietic stem cell transplantation. We also make recommendations for critical strategies to prevent relapse after transplantation and challenges that must be addressed to ensure success.

Loss of Angiopoietin-like 7 diminishes the regeneration capacity of hematopoietic stem and progenitor cells

Successful expansion of hematopoietic stem cells (HSCs) would benefit the use of HSC transplants in the clinic. Angiopoietin-like 7 promotes the expansion of hematopoietic stem and progenitor cells (HSPC) in vitro and ex vivo. However, the impact of loss of Angptl7 on HSPCs in vivo has not been characterized. Here, we generated Angptl7-deficient mice by TALEN-mediated gene targeting and found that HSC compartments in Angptl7-null mice were compromised. In addition, wild type (WT) HSPCs failed to repopulate in the BM of Angptl7-null mice after serial transplantations while the engraftment of Angptl7-deficient HSPCs in WT mice was not impaired. These results suggest that Angptl7 is required for HSPCs repopulation in a non-cell autonomous manner.

Haploidentical hematopoietic transplantation without T-cell depletion: current status and future perspectives

Human leukocyte antigen (HLA)-haploidentical hematopoietic stem cell transplantation (HLA-haplo HSCT) without T-cell depletion has tremendously progressed over the past 20 years and has become a feasible treatment option for leukemia patients without an HLA-identical sibling donor. Advances in conditioning regimens, graft manipulation, and pharmacological graft-versus-host disease (GVHD) prophylaxis have reduced the risk of fatal graft failure and severe GVHD, two of the most serious complications of traversing the HLA barrier. According to clinical observations, killer immunoglobulin-like receptor (KIR) mismatch and donor-specific anti-HLA (DSA) antibodies-negative status play potential roles in reducing the risk of GVHD and graft failure following HLA-haploidentical SCT. New strategies to improve transplant outcomes include donor lymphocyte, NK cell and selected T-cell subset infusion, mesenchymal stem cell (MSC) co-transplantation and interleukin-2 (IL-2) application. Future challenges remain in improving post-transplant immune reconstitution and finding the best approach to reduce the incidence and severity of GVHD while simultaneously preserving the graft-versus leukemia effect to prevent the recurrence of underlying malignancy.

T-cell-replete haploidentical stem cell transplantation is highly efficacious for relapsed and refractory childhood acute leukaemia

BACKGROUND

Despite improvements in first-line therapies, the outcomes of relapsed or refractory childhood acute leukaemia that has not achieved complete remission after relapse, has relapsed after stem cell transplantation (SCT), has primary induction failure and has relapsed with a very unfavourable cytogenetic risk profile, are dismal.

OBJECTIVES AND METHODS

We evaluated the feasibility and efficacy of T-cell-replete haploidentical peripheral blood stem cell transplantation (haplo-SCT) with low-dose anti-human thymocyte immunoglobulin (ATG), tacrolimus, methotrexate and prednisolone (PSL) in 14 paediatric patients with high-risk childhood acute leukaemia.

RESULTS

All patients achieved complete engraftment. The median time to reaching an absolute neutrophil count of more than 0.5 × 10(9) L(-1) was 14 days. Acute graft-vs-host disease (aGVHD) of grades II-IV and III-IV developed in 10 (71%) and 2 (14%) patients, respectively. Treatment-related mortality and relapse occurred in one (7%) patient and six (43%) patients, respectively. Eleven patients were alive and seven of them were disease-free with a median follow-up of 36 months (range: 30-159 months). The probability of event-free survival after 2 years was 50%.

CONCLUSION

These findings indicate that T-cell-replete haplo-SCT, with low-dose ATG and PSL, provides sustained remission with an acceptable risk of GVHD in paediatric patients with advanced haematologic malignancies.

HLA and KIR genotyping correlates with relapse after T-cell-replete haploidentical transplantation in chronic myeloid leukaemia patients

Background:

Conflicting results have been reported regarding the predicative roles of alloreactive natural killer (NK) cells on the outcomes of transplantation in leukaemia patients.

Methods:

We prospectively analysed the human leukocyte antigen (HLA) typing of donor–recipient pairs and the KIR typing of the donors in 97 CML patients to address the predictive roles of NK cells in relapse undergoing T-cell-replete haploidentical transplantation.

Results:

Patients with class I ligands for the donor-inhibitory KIR gene exhibited decreased molecular and haematologic relapse rates (P=0.003 and P=0.015, respectively). There was a significantly reduced risk of molecular and haematologic relapse in patients with HLA-C1C2 or C2C2 who accepted donors with KIR2DS1 or in patients with HLA-Bw4 who accepted donors with KIR3DS1 (‘recipient with relevant KIR ligand for donor-activating KIR', n=25), compared with the remaining transplants (n=72, P=0.009 and P=0.009, respectively). In addition, the presence of class I ligand in the recipients of donor-activating KIR contributed to a decreased relapse rate in patients lacking class I ligand in the recipient of donor-inhibitory KIR (P=0.04 and P=0.03, respectively).

Conclusions:

This study suggests that the presence of class I ligands for the donor-activating or donor-inhibitory KIR gene in the recipient might confer some protection against leukaemic relapse in T-cell-replete haploidentical transplantation.

At the Bench: Preclinical rationale for exploiting NK cells and γδ T lymphocytes for the treatment of high-risk leukemias

NK cells and γδ T lymphocytes display potent cytolytic activity against leukemias and CMV-infected cells and are thus, promising immune effector cells in the context of allo-HSCT. NK cells express HLA class I-specific inhibitory receptors and preferentially kill HLA class I(low) tumors or virus-infected cells. Killing occurs upon engagement of activating NKRs with ligands that are up-regulated on tumors and infected cells. A similar activating receptor/ligand interaction strategy is used by γδ T cells, which in addition, use their TCRs for recognition of phosphorylated antigens and still largely undefined ligands on tumor cells. In the haploidentical allo-HSCT setting, alloreactive NK cells, derived from donor HSCs, can exert potent antileukemia activity and kill residual patient DCs and T cells, thus preventing GvHD and graft rejection. However, generation of KIR(+) alloreactive NK cells from HSCs requires many weeks, during which leukemia relapses, and life-threatening infections may occur. Importantly, mature NK cells and γδ T cells can control certain infectious agents efficiently, in particular, limit CMV reactivation, and infusion of such donor cells at the time of HSCT has been implemented. Development of novel, cell-based immunotherapies, allowing improved trafficking and better targeting, will endow NK cells and γδ T lymphocytes with enhanced anti-tumor activity, also making them key reagents for therapies against solid tumors. The clinical aspects of using NK cells and γδ T lymphocytes against hematological malignancies, including the allo-HSCT context, are reviewed in the related side-by-side paper by Locatelli and colleagues [1].

Optimization of the immunomagnetic selection in microcythemic donors enrolled for haploidentical transplantation

BACKGROUND

Immunomagnetic cell selection (ICS) cells is increasingly used in allogeneic hematopoietic transplantation in order to reduce the T cells quantity. The aim of this study was to evaluate an protocol based on Ficoll method before ICS.

STUDY DESIGN AND METHODS

The automated procedure was compared with the standard method. In the group 1 the cell processing involves the extraction of the buffy-coat by Ficoll before incubation with antibodies. This procedure was performed with the Sepax S-100 device. The efficacy of this automated procedure was compared with the group 2. In this group, the cell washing and the incubation were performed through the standard method. The CD34+ cells collected by apheresis (HPC-A) were selected with ICS.

RESULTS

The results obtained after Ficoll procedure, showed a total nucleated cells (TNCs) and CD34+ cells recovery of 85.73% (75.90-90.63; SD 4.25) and 79.31% (51.77-112.31; SD 18.40), respectively. The TNC and CD34+ cells recovery after the pre-incubation washing performed through the standard method, was 75.54% (38.36-97.76; SD 22.5) and 61.51% (30.87-81.79; SD 19.3), respectively. The CD34+ cells recovery after ICS was 79% (51.77-100; SD 18.40) and 44% (15.57-88.24; SD 25.91) in the group 1 and the group 2, respectively. This difference was statistically significant (p=0.001).

CONCLUSION

The efficacy of the ICS which resulted to be higher in the group 1 compared to the group 2. Overall, our data suggest that the Ficoll procedure before incubation is suitable for the clinical routine in the ICS for haploidentical transplantation in patients affected by thalassemia.

Cellular mechanism for granulocyte-colony stimulating factor in the prevention of graft-versus-host disease in combined bone marrow and peripheral blood transplantation for hematological malignancies: the composition in collection

Despite improvements in transplant immunology and clinical and supportive care, acute graft-versus-host disease (aGVHD) remains a clinical challenge and a major cause of morbidity and mortality for patients after allogeneic hematopoietic stem cell transplantation (HSCT). Many ways have been used to prevent and treat aGVHD, however, long-term survival remains poor. The key to improve aGVHD outcomes may, in fact, rest upon successful initial therapy. The HLA-matched HSCT was limited by the shortage of suitable donors. Unmanipulated haploidentical/mismatched related transplantation with combined granulocyte-colony stimulating factor (G-CSF)-mobilized peripheral blood stem cells and G-CSF-mobilized bone marrow as a stronger aGVHD inhibition and graft-versus-leukemia effect, has been developed as an alternative transplantation strategy for patients with hematologic malignancies for the advantage of immediate donor availability, ability to select the best of many relatives, controlled graft composition and immediate access to donor-derived cellular therapies if required after transplantation. G-CSF is a potent hematopoietic cytokine, which is produced by fibroblasts, monocytes, and endothelial cells. G-CSF regulates production of neutrophils within the bone marrow and affects neutrophil progenitor proliferation, maturation and is also involved in mobilization of granulocytes, stem and progenitor cells, which has an important role in this transplantation. In this article, we review the possible mechanism for this combined G-CSF-mobilized HSCT in the prevention of aGVHD. Monocytes, T cells, Tregs cells, DC, adhesive molecule, NK cell/KIR ligand mismatching and mesenchymal stem cells may be involved in this transplantation.

Differential outcome of neurological HCMV infection in two hematopoietic stem cell transplant recipients

BACKGROUND

Human cytomegalovirus (HCMV) infection of the central nervous system (CNS) is a rare but life threatening condition which may follow hematopoietic stem cell transplantation. Diagnosis, monitoring and treatment approaches rely on anecdotal reports.

CASE PRESENTATIONS

The different outcomes of HCMV CNS disease in an adult and a pediatric T-cell depleted hematopoietic stem cell transplant (HSCT) recipient are reported. In the first case, HCMV encephalitis emerged in the context of simultaneous impairment of the T- and B-cell immunity. Antiviral treatment only reduced viral load in peripheral blood and the patient died. In the second case, an HCMV radiculopathy was observed and antiviral treatment was adjusted on the basis of intrathecal drug level. In addition, donor HCMV-specific cytotoxic T lymphocytes (CTLs) were infused. Viral load in the CNS decreased and the patient recovered from the acute event. In neither case were drug-resistant HCMV variants observed in blood or CNS samples.

CONCLUSIONS

T-cell depleted HSCT appears a predisposing condition for CNS HCMV infection since never observed in other HSCT recipients at our center in the last 15 years. Intensive diagnostic approaches and timely aggressive combination treatments might improve clinical outcome in these patients.

Clinical applications of mesenchymal stem cells

Mesenchymal stem cells (MSC) have generated a great amount of enthusiasm over the past decade as a novel therapeutic paradigm for a variety of diseases. Currently, MSC based clinical trials have been conducted for at least 12 kinds of pathological conditions, with many completed trials demonstrating the safety and efficacy. This review provides an overview of the recent clinical findings related to MSC therapeutic effects. Roles of MSCs in clinical trials conducted to treat graft-versus-host-disease (GVHD) and cardiovascular diseases are highlighted. Clinical application of MSC are mainly attributed to their important four biological properties- the ability to home to sites of inflammation following tissue injury when injected intravenously; to differentiate into various cell types; to secrete multiple bioactive molecules capable of stimulating recovery of injured cells and inhibiting inflammation and to perform immunomodulatory functions. Here, we will discuss these four properties. Moreover, the issues surrounding clinical grade MSCs and principles for MSC therapeutic approaches are also addressed on the transition of MSCs therapy from bench side to bedside.

Molecular monitoring of minimal residual disease in two patients with MLL-rearranged acute myeloid leukemia and haploidentical transplantation after relapse

This report describes the clinical courses of two acute myeloid leukemia patients. Both had MLL translocations, the first a t(10;11)(p11.2;q23) with MLL-AF10 and the second a t(11;19)(q23;p13.1) with MLL-ELL fusion. They achieved a clinical remission under conventional chemotherapy but relapsed shortly after end of therapy. Both had a history of invasive mycoses (one had possible pulmonary mycosis, one systemic candidiasis). Because no HLA-identical donor was available, a haploidentical transplantation was performed in both cases. Using a specially designed PCR method for the assessment of minimal residual disease (MRD), based on the quantitative detection of the individual chromosomal breakpoint in the MLL gene, both patients achieved complete and persistent molecular remission after transplantation. The immune reconstitution after transplantation is described in terms of total CD3⁺/CD4⁺, CD3⁺/CD8⁺, CD19⁺, and CD16⁺/CD56⁺ cell numbers over time. The KIR and HLA genotypes of donors and recipients are reported and the possibility of a KIR-mediated alloreactivity is discussed. This report illustrates that haploidentical transplantation may offer a chance of cure without chronic graft-versus-host disease in situations where no suitable HLA-identical donor is available even in a high-risk setting and shows the value of MRD monitoring in the pre- and posttransplant setting.

Allogeneic hematopoietic stem cell transplantation in China: where we are and where to go

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective and sometimes the only curative therapy for patients with certain hematological diseases. Allo-HSCT has been practiced in China for approximately 30 years, and great improvements have been made within the past decade, particularly in fields such as the haploidentical HSCT system, strategies to overcome relapse and GVHD, and modified HSCT for elderly patients. This review will describe the current situation and provide a prospective of these unique aspects of Allo-HSCT in China.

The chemokine system in allogeneic stem-cell transplantation: a possible therapeutic target?

Further improvements in allogeneic stem-cell transplantation will probably depend on a better balance between immunosuppression to control graft-versus-host disease and immunological reconstitution sufficient to ensure engraftment, reduction of infection-related mortality and maintenance of post-transplant antileukemic immune reactivity. The chemokine network is an important part of the immune system, and, in addition, CXCL12/CXCR4 seem to be essential for granulocyte colony-stimulating factor-induced stem-cell mobilization. Partial ex vivo graft T-cell depletion based on the expression of specific chemokine receptors involved in T-cell recruitment to graft-versus-host disease target organs may also become a future therapeutic strategy; an alternative approach could be pharmacological inhibition (single-receptor inhibitors or dual-receptor inhibitors) in vivo of specific chemokine receptors involved in this T-cell recruitment. Future clinical studies should therefore be based on a better characterization of various immunocompetent cells, including their chemokine receptor profile, both in the allografts and during post-transplant reconstitution.

Unmanipulated HLA-mismatched/haploidentical peripheral blood stem cell transplantation for high-risk hematologic malignancies

BACKGROUND

Haploidentical hematopoietic stem cell transplantation (HSCT) has been increasingly applied in high-risk hematologic patients due to the absence of HLA-matched donors. The aim of this study was to investigate the efficacy and safety of unmanipulated haploidentical allogeneic peripheral blood stem cells transplantation (PBSCT) for hematologic malignancies.

STUDY DESIGN AND METHODS

Patients who underwent unmanipulated HLA-mismatched/haploidentical PBSCT from July 2007 to March 2010 with high-risk hematologic malignancies were enrolled for retrospective analysis.

RESULTS

Twenty-one patients with high-risk hematologic malignancies underwent unmanipulated HLA-mismatched/haploidentical PBSCT with myeloablative conditioning. The numbers of CD34+ cells infused at transplantation were 4.81 (range, 2.61-11.47)×10(6)/kg. Patients achieved myeloid and platelet engraftment at a median of 16.5 and 20 days, respectively. The cumulative incidence of acute graft-versus-host disease (GVHD) on Day 100 was 52.7±10.7%, and the 2-year cumulative incidence of chronic GVHD was 39.5±10.6%. The cumulative incidences of cytomegalovirus antigenemia and hemorrhagic cystitis within 100 days after PBSCT were 59.5±16.7 and 34.8±13.3%, respectively. One hundred-day transplantation-related mortality (TRM) rate and the 2-year cumulative TRM rate were 14.3 and 20.5±7.8%, respectively. The 2-year cumulative overall survival was 62.1±11.4% and the probability of disease-free survival at 2 years was 55.6±10.7% with a 16-month median follow-up.

CONCLUSION

Unmanipulated PBSCT is a promising protocol in HLA-mismatched/haploidentical transplant settings.

Frequency analysis of TRBV subfamily sjTRECs to characterize T-cell reconstitution in acute leukemia patients after allogeneic hematopoietic stem cell transplantation

Background

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) leads to a prolonged state of immunodeficiency and requires reconstitution of normal T-cell immunity. Signal joint T-cell receptor excision DNA circles (sjTRECs) are markers of developmental proximity to the thymus that have been used to evaluate thymic function related to T-cell immune reconstitution after HSCT. To assess the proliferative history in different T-cell receptor beta variable region (TRBV) subfamilies of T cells after HSCT, expansion of TRBV subfamily-naive T cells was determined by analysis of a series of TRBV-BD1 sjTRECs.

Methods

sjTRECs levels were detected by real-time quantitative polymerase chain reaction (PCR) in peripheral blood mononuclear cells (PBMCs) from 43 Chinese acute leukemia patients who underwent allo-HSCT. Twenty-three TRBV-BD1 sjTRECs were amplified by semi-nested PCR. Sixteen age-matched healthy volunteers served as normal controls.

Results

sjTRECs levels were low or undetectable in the first 6 weeks after allo-HSCT and increased after 8 weeks post HSCT; however, sjTRECs levels at week 20 post-HSCT were still less than normal controls. Frequencies of TRBV subfamily sjTRECs in PBMCs from recipients at week 8 post-HSCT (29.17 ± 20.97%) or at week 16 post-HSCT (38.33 ± 9.03%) were significantly lower than those in donors (47.92 ± 13.82%) or recipients at pre-HSCT (45.83 ± 14.03%). However, frequencies of TRBV subfamily sjTRECs in recipients at week 30 post-HSCT (42.71 ± 21.62%) were similar to those in donors and recipients at pre-HSCT. sjTRECs levels in donors had a positive linear correlation with sjTRECs levels in recipients within 8-12 weeks post-HSCT. Patients with acute graft-versus-host disease (GVHD) or chronic GVHD had profoundly reduced TRECs levels during the first year post-HSCT. Frequencies of BV22-BD1 sjTRECs and BV23-BD1 sjTRECs in patients with GVHD were significantly lower than those in recipients at pre-HSCT, and the frequencies of BV22-BD1 sjTRECs in patients with GVHD were significantly lower than those in donors.

Conclusions

Reconstitution of thymic output function resulted in a period of immunodeficiency, with low or undetectable TRECs after transplantation, although fludarabine-based dose-reduced conditioning regimens were used. GVHD could affect reconstitution of thymic output function and reduce sjTRECs levels and frequencies of TRBV-BD1 sjTRECs. Low frequency of BV22-BD1 and BV23-BD1 sjTRECs might be associated with GVHD.

Progress and prospects: graft-versus-host disease

Graft-versus-host disease (GvHD) is one of the major complications of allogeneic hematopoietic stem cell transplantation, an otherwise highly effective therapeutic modality for patients affected by hematological diseases. The main inducers of GvHD are alloreactive donor T cells, which recognize host antigens presented by recipient cells. The critical role of lymphocytes in GvHD is well documented by the observation that T-cell depletion from the graft prevents GvHD. Unfortunately, the removal of donor lymphocytes from the graft increases the incidence of disease relapse and life-threatening infectious complications. Gene transfer technologies are promising tools to manipulate donor T-cell immunity to enforce graft-versus-tumor/graft-versus-infection while preventing or controlling GvHD. For this purpose, several cell and gene transfer approaches have been investigated at the preclinical level and implemented in clinical trials.

Positive immunomagnetic CD34(+) cell selection in haplo-identical transplants in beta-thalassemia patients: removal of platelets using an automated system

BACKGROUND AIMS

Immunomagnetic CD34(+) cell selection (ICS) is utilized in autologous and allogeneic transplants. In the first case it is used to reduce the neoplastic contamination of concentrates, while in the second case it is needed to carry out a T-depletion of cell concentrates in order to reduce the incidence of graft-versus-host disease (GvHD) in patients who have undergone haplo-identical transplants.

METHODS

The efficacy of CliniMACS technology, after reduction of platelet contamination, incubation of monoclonal antibodies (MAb) and successive washings of concentrates, performed in 16 ICS using the standard method without reducing platelet content, was compared with the use of the automated system CytoMate, which was carried out in 46 ICS.

RESULTS

In the group of ICS carried out after automatic manipulation, a significant statistical difference in purity was noted (91.39% versus 83.57, P = 0.017) compared with the group of ICS carried out with the standard procedure. The same significant difference was noted in relation to the remaining percentages of CD3(+) and CD19(+) cells (2.31% versus 5.68%, P = 0.012, and 1.58% versus 2.71%, P = 0.014, respectively). Recovery of CD34+ cells overlapped in the two groups (70.49% versus 68.39%, P = 0.774).

CONCLUSIONS

Immunomagnetic selection carried out using the automated procedure was more efficient, producing a purer sample, more efficient T-depletion and optimal reduction of B cells, without influencing cell recovery. Furthermore, conforming to good manufacturing practice (GMP) guidelines, the entire procedure with CytoMate took place in a contamination-controlled environment.

Unmanipulated HLA-mismatched/haploidentical blood and marrow hematopoietic stem cell transplantation

Extensive ex vivo T cell-depleted or unmanipulated haploidentical transplantation provides benefits of rapid and near universal donor availability for patients without HLA-identical sibling donors or those who urgently need transplant. However, CD34 selected haplotype mismatched transplantation was limited by delayed immune reconstitution (IR), although this protocol has now been an acceptable approach. Recently, Peking University researchers developed a novel approach to HLA-mismatched/haploidentical blood and marrow transplantation without in vitro T cell depletion (GIAC protocol). This review summarizes transplant outcomes, and factors correlating with transplant outcomes following the GIAC protocol. Moreover, future challenges in improving posttransplant IR and finding the best approach reducing the incidence and severity of GVHD, whereas preserving graft-versus-leukemia effect to prevent the recurrence of underlying malignancy, are also discussed.