Peripheral blood grafts from unrelated donors are associated with increased acute and chronic graft-versus-host disease without improved survival

Busulfan with 400 centigray of total body irradiation and higher dose fludarabine: An alternative regimen for hematopoietic stem cell transplantation in pediatric acute lymphoblastic leukemia

BACKGROUND

Hematopoietic stem cell transplantation can be curative for children with difficult-to-treat leukemia. The conditioning regimen utilized is known to influence outcomes. We report outcomes of the conditioning regimen used at the Alberta Children's Hospital, consisting of busulfan (with pharmacokinetic target of 3750 μmol*min/L/day ±10%) for 4 days, higher dose (250 mg/m2 ) fludarabine and 400 centigray (cGy) of total body irradiation.

PROCEDURE

This retrospective study involved children receiving transplant for acute lymphoblastic leukemia (ALL). It compared children who fell within the target range for busulfan with those who were either not measured or were measured and fell outside this range. All other treatment factors were identical.

RESULTS

Twenty-nine children (17 within target) were evaluated. All subjects engrafted neutrophils with a median [interquartile range] time of 14 days [8-30 days]. The cumulative incidence of acute graft-versus-host disease was 44.8% [95% confidence interval, CI: 35.6%-54.0%], while chronic graft-versus-host disease was noted in 16.0% [95% CI: 8.7%-23.3%]. At 2 years, the overall survival was 78.1% [95% CI: 70.8%-86.4%] and event-free survival was 74.7% [95% CI: 66.4%-83.0%]. Cumulative incidence of relapse was 11.3% [95% CI: 5.1%-17.5%]. There were no statistically significant differences in between the group that received targeted busulfan compared with the untargeted group.

CONCLUSION

Our conditioning regiment for children with ALL resulted in outcomes comparable to standard treatment with acceptable toxicities and significant reduction in radiation dose. Targeting busulfan dose in this cohort did not result in improved outcomes.

Prospective PTCTC trial of myeloablative haplo-BMT with posttransplant cyclophosphamide for pediatric acute leukemias

Promising results have been reported for adult patients with high-risk hematologic malignancies undergoing haploidentical bone marrow transplant (haploBMT) with posttransplant cyclophosphamide (PTCy). To our knowledge, we report results from the first multicenter trial for pediatric and young adult patients with high-risk acute leukemias and myelodysplastic syndrome (MDS) in the Pediatric Transplantation and Cellular Therapy Consortium. Nine centers performed transplants in 32 patients having acute leukemias or MDS, with myeloablative conditioning (MAC), haploBMT with PTCy, mycophenolate mofetil, and tacrolimus. The median patient age was 12 years. Diagnoses included AML (15), ALL (11), mixed-lineage leukemia (1), and MDS (5). Transplant-related mortality (TRM) at 180 days was 0%. The cumulative incidence (CuI) of grade 2 acute graft-versus-host disease (aGVHD) on day 100 was 13%. No patients developed grades 3-4 aGVHD. The CuI of moderate-to-severe chronic GVHD (cGVHD) at 1 year was 4%. Donor engraftment occurred in 27 patients (84%). Primary graft failures included 3 patients who received suboptimal bone marrow grafts; all successfully engrafted after second transplants. The CuI of relapse at 1 year was 32%, with more relapse among patients MRD positive pre-BMT vs MRD negative. Overall survival rates at 1 and 2 years were 77% and 73%, and event-free survival rate at 1 and 2 years were 68% and 64%. There was no TRM or severe aGVHD, low cGVHD, and favorable relapse and survival rates. This successful pilot trial has led to a phase 3 trial comparing MAC haploBMT vs HLA-matched unrelated donor BMT in the Children's Oncology Group. This trial was registered at www.clinicaltrials.gov as #NCT02120157.

Role of CD19 Chimeric Antigen Receptor T Cells in Second-Line Large B Cell Lymphoma: Lessons from Phase 3 Trials. An Expert Panel Opinion from the American Society for Transplantation and Cellular Therapy

Since 2017, 3 CD19-directed chimeric antigen receptor (CAR) T cell therapies-axicabtagene ciloleucel, tisagenlecleucel, and lisocabtagene maraleucel-have been approved for relapsed/refractory aggressive diffuse large B cell lymphoma after 2 lines of therapy. Recently, 3 prospective phase 3 randomized clinical trials were conducted to define the optimal second-line treatment by comparing each of the CAR T cell products to the current standard of care: ZUMA-7 for axicabtagene ciloleucel, BELINDA for tisagenlecleucel, and TRANSFORM for lisocabtagene maraleucel. These 3 studies, although largely addressing the same question, had different outcomes, with ZUMA-7 and TRANSFORM demonstrating significant improvement with CD19 CAR T cells in second-line therapy compared with standard of care but BELINDA not showing any benefit. The US Food and Drug Administration has now approved axicabtagene ciloleucel and lisocabtagene maraleucel for LBCL that is refractory to first-line chemoimmunotherapy or relapse occurring within 12 months of first-line chemoimmunotherapy. Following the reporting of these practice changing studies, here a group of experts convened by the American Society for Transplantation and Cellular Therapy provides a comprehensive review of the 3 studies, emphasizing potential differences, and shares perspectives on what these results mean to clinical practice in this new era of treatment of B cell lymphomas.

Advantages of peripheral blood stem cells from unrelated donors versus bone marrow transplants in outcomes of adult acute myeloid leukemia patients

BACKGROUND AIMS

In allogeneic stem cell transplantation, unrelated donors are chosen in cases where appropriate related donors are not available. Peripheral blood stem cells (PBSCs) are more often selected as a graft source than bone marrow (BM). However, the prognostic benefits of PBSCs versus BM transplants from unrelated donors have not been carefully examined in patients with acute myeloid leukemia (AML). This study compared outcomes of adult AML patients who underwent unrelated PBSC and BM transplantation, evaluating post-transplant complications, including engraftment, graft-versus-host disease (GVHD) and infections, and determined subgroups of patients who are most likely to benefit from unrelated PBSCs compared with BM transplants.

METHODS

The authors analyzed 2962 adult AML patients who underwent unrelated PBSC or BM transplants between 2011 and 2018 (221 PBSC and 2741 BM) using the Japanese nationwide registry database, in which graft source selection is not skewed toward PBSCs.

RESULTS

In 49.7% of patients, disease status at transplantation was first complete remission (CR1). In 57.1% of cases, HLA-matched donors were selected. Myeloablative conditioning was performed in 75.1% of cases, and anti-thymocyte globulin (ATG) was added to conditioning in 10.5%. Multivariate analyses showed a trend toward favorable non-relapse mortality (NRM) in PBSC recipients compared with BM recipients (hazard ratio [HR], 0.731, P = 0.096), whereas overall survival (OS) (HR, 0.959, P = 0.230) and disease-free survival (DFS) (HR, 0.868, P = 0.221) were comparable between PBSC and BM recipients. Although the rate of chronic GVHD (cGVHD) was significantly higher in PBSC patients (HR, 1.367, P = 0.016), NRM was not increased, mainly as a result of significantly reduced risk of bacterial infections (HR, 0.618, P = 0.010), reflecting more prompt engraftments in PBSC recipients. Subgroup analyses revealed that PBSC transplantation was advantageous in patients transplanted at CR1 and in those without ATG use. PBSC recipients experienced significantly better OS and/or DFS compared with BM recipients in this patient group.

CONCLUSIONS

The authors' results confirmed the overall safety of unrelated PBSC transplantation for adult AML patients and suggested an advantage of PBSCs, especially for those in CR1. Further optimization of the prophylactic strategy for cGVHD is required to improve the overall outcome in transplantation from unrelated PBSC donors.

Risk factors for adverse outcomes following haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide: a two-center analysis

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative therapy for several malignant hematologic diseases and alternative donors, including haploidentical, play a significant role in HCT. Despite the increasing use of haplo-HCT with PTCy, some questions remain open. The objective of the present study was to investigate risk factors for adverse outcomes after haplo-HCT with PTCy. This is a retrospective study conducted at two Brazilian centers. A total of 103 patients with hematologic malignancies who underwent first allogeneic, haploidentical HCT with PTCy were included. Risk factors for death were age at transplant (HR = 1.03 for each year; p = 0.002) and high/very high disease risk index (DRI; HR = 2.77; p = 0.0007) and mother as the donor compared with other donors (HR = 3.53; p = 0.005). In multivariate analysis, PFS was significantly poorer for older patients (HR = 1.02; p = 0.006), high/very high DRI (HR = 2.39; p = 0.003), and mother as the donor compared with other donors (HR = 3.18; p = 0.006). Relapse rate was higher for high/very high DRI (HR = 4.01; p = 0.002) and mother as the donor compared with other donors (HR = 2.52; p = 0.05). NRM was higher for older patients (HR = 1.03 for each year; p = 0.03). Tacrolimus was a protective factor for grades II-IV aGVHD (HR = 0.46; p = 0.04) compared with cyclosporine. Peripheral blood (PBSC) was a risk factor for cGVHD (HR = 3.48; p = 0.006), while tacrolimus was protective (HR = 0.30; p = 0.009). Mother as the donor compared with other donors was also a risk factor for poorer OS, PFS, and relapse, suggesting that this combination should be avoided. Tacrolimus was protective for both grades II-IV aGVHD and cGVHD, suggesting that tacrolimus may be more effective than cyclosporine in preventing GVHD. PBSC was a risk factor for cGVHD without any impact on relapse. Prospective studies comparing tacrolimus with cyclosporine are awaited.

Risk Factors for Graft-Versus-Host Disease and Survival in Pediatric Hematopoietic Stem Cell Transplant Recipients: A Single-Center Experience

OBJECTIVES

Graft-versus-host disease is still one of the most important complications after hematopoietic stem cell transplantation. The risk factors remain unclear, with effects of graft-versus-host disease on survival varying among different centers. We aimed to determine risk factors that may affect development of graft-versus-host disease and the corresponding patient survival rates at a single pediatric hematopoietic stem cell transplant unit.

METHODS

Our study included 104 of 118 pediatric patients who underwent allogeneic hematopoietic stem cell transplant at our institute between 2005 and 2018. Patient characteristics, clinical information, pretransplant and posttransplant factors, and laboratory parameters were obtained from the database.

RESULTS

Acute graft-versus-host disease was seen in 19 pediatric patients. Chronic graft-versus-host disease, which was seen in 13 of our pediatric study patients, occurred more often in those with peripheral blood stem cell than in those with bone marrow transplant (odds ratio of 9.969; 95% CI, 1.040-95.547; P = .046). Female donor-to-male recipient transplant was significantly associated with incidence of chronic graft-versus-host disease (odds ratio of 8.51; 95% CI, 1.323-54.843; P = .024). Later neutrophil engraftment was associated with incidence of acute graft-versus-host disease (odds ratio of 1.107; 95% CI, 1.012-1.212; P = .02).

CONCLUSIONS

Although there are some known risk factors for graft-versus-host disease in adult patients, little is known about risk factors in children. In our comprehensive study in pediatric patients, we found that peripheral blood stem cell transplant, female-tomale transplant, and later neutrophil engraftment were associated with incidence of graft-versus-host disease. Although peripheral blood as a source of stem cells and female-to-male transplant are known risk factors, later neutrophil engraftment was a new finding as a possible risk factor for acute graft-versushost disease. This finding requires further verification in future prospective studies.

Allogeneic blood or marrow transplantation with haploidentical donor and post-transplantation cyclophosphamide in patients with myelofibrosis: a multicenter study

We report the results from a multicenter retrospective study of 69 adult patients who underwent haploidentical blood or marrow transplantation (haplo-BMT) with post-transplantation cyclophosphamide (PTCy) for chronic phase myelofibrosis. The median age at BMT was 63 years (range, 41-74). Conditioning regimens were reduced intensity in 54% and nonmyeloablative in 39%. Peripheral blood grafts were used in 86%. The median follow-up was 23.1 months (range, 1.6-75.7). At 3 years, the overall survival, relapse-free survival (RFS), and graft-versus-host-disease (GVHD)-free-RFS were 72% (95% CI 59-81), 44% (95% CI 29-59), and 30% (95% CI 17-43). Cumulative incidences of non-relapse mortality and relapse were 23% (95% CI 14-34) and 31% (95% CI 17-47) at 3 years. Spleen size ≥22 cm or prior splenectomy (HR 6.37, 95% CI 2.02-20.1, P = 0.002), and bone marrow grafts (HR 4.92, 95% CI 1.68-14.4, P = 0.004) were associated with increased incidence of relapse. Cumulative incidence of acute GVHD grade 3-4 was 10% at 3 months and extensive chronic GVHD was 8%. Neutrophil engraftment was reported in 94% patients, at a median of 20 days (range, 14-70). In conclusion, haplo-BMT with PTCy is feasible in patients with myelofibrosis. Splenomegaly ≥22 cm and bone marrow grafts were associated with a higher incidence of relapse in this study.

Ixazomib for Chronic Graft-versus-Host Disease Prophylaxis following Allogeneic Hematopoietic Cell Transplantation

Chronic graft-versus-host disease (cGVHD) is major cause of morbidity and mortality following allogeneic hematopoietic cell transplantation (HCT). Ixazomib is an oral, second-generation, proteasome inhibitor that has been shown in preclinical models to prevent GVHD. We conducted a phase I/II trial in 57 patients to evaluate the safety and efficacy of ixazomib administration for cGVHD prophylaxis in patients undergoing allogeneic HCT. Oral ixazomib was administered on a weekly basis for a total of 4 doses, beginning days +60 through +90, to recipients of matched related donor (MRD, n = 25) or matched unrelated donor (MUD, n = 26) allogeneic HCT in phase II portion of the study, once the recommended phase II dose of 4 mg was identified in phase I (n = 6). All patients received peripheral blood graft and standard GVHD prophylaxis of tacrolimus and methotrexate. Ixazomib administration was safe and well tolerated, with thrombocytopenia, leukopenia, gastrointestinal complaints, and fatigue the most common adverse events (>10%). In phase II (n = 51), the cumulative incidence of cGVHD at 1 year was 36% (95% confidence interval [CI], 19% to 54%) in the MRD cohort and 39% (95% CI, 21% to 56%) in the MUD cohort. One-year cumulative incidence of nonrelapse mortality (NRM) and relapse was 0% and 20% (95% CI, 8% to 36%) in the MRD cohort, respectively. In the MUD cohort, the respective NRM and relapse rates were 4% (0% to 16%) and 34% (17% to 52%). The outcomes on the study were compared post hoc with contemporaneous matched Center for International Blood and Marrow Transplant Research (CIBMTR) controls. This post hoc analysis showed no significant improvement in cGVHD rates in both the MRD (hazard ratio [HR] = 0.85, P = .64) or MUD cohorts (HR = 0.68, P = .26) on the study compared with CIBMTR controls. B cell activating factor plasma levels were significantly higher after ixazomib dosing in those who remained cGVHD free compared with those developed cGVHD. This study shows that the novel strategy of short-course oral ixazomib following allogeneic HCT is safe but did not demonstrate significant improvement in cGVHD incidence in recipients of MRD and MUD transplantation compared with matched CIBMTR controls. This study is registered at www.clinicaltrials.gov as NCT02250300.

Clinical characteristics and cytokine biomarkers in patients with chronic graft-vs-host disease persisting seven or more years after diagnosis

Chronic graft-versus-host disease (cGVHD) is the leading late complication after allogeneic hematopoietic stem cell transplantation (HSCT). Many patients receive multiple lines of systemic therapy until cGVHD resolves, but about 15% remain on systemic treatment for more than 7 years after cGVHD diagnosis. This study describes the clinical and biological factors of patients who present with cGVHD persisting for ≥7 years (persistent cGVHD). Patients with persistent cGVHD (n = 38) and those with cGVHD for <1 year (early cGVHD) (n = 83) were enrolled in a prospective cross-sectional natural history study. Patients in the persistent cGVHD group were a median of 10.2 years from cGVHD diagnosis (range 7-27 years). Fifty-eight percent of persistent cGVHD patients (22/38) were receiving systemic immunosuppression, compared to 88% (73/83) in the early cGVHD group. In multivariable analysis, bone marrow (BM) stem cell source, presence of ENA autoantibodies, higher NIH lung score, higher platelet counts, and higher IgA levels were significantly associated with persistent cGVHD. A high sensitivity panel of serum biomarkers including seven cytokines diagnostic for cGVHD was analyzed and showed significantly lower levels of BAFF and CXCL10 in patients with persistent cGVHD. In conclusion, standardly accepted clinical measures of disease severity may not accurately reflect disease activity in patients with persistent cGVHD. However, many patients with persistent cGVHD are still receiving systemic immunosuppression despite lacking evidence of disease activity. Development of reliable clinical biomarkers of cGVHD activity may help guide future systemic treatments.

Influence of HLA 1-3-locus mismatch and antithymocyte globulin administration in unrelated bone marrow transplantation

For patients without an HLA-matched donor, an HLA-mismatched unrelated donor (MMUD) has been considered as an alternative donor in allogeneic hematopoietic cell transplantation (allo-HCT). We conducted a nationwide retrospective study to compare the transplant outcomes among 1-, 2-, and 3-locus (allele/antigen) mismatched unrelated donors (1MMUD n = 2044, 2MMUD n = 492, and 3MMUD n = 73) in allo-HCT and to assess the impact of antithymocyte globulin (ATG) in allo-HCT from 1-3MMUD. 2MMUD and 3MMUD were independent significant adverse factors for grade III-IV acute graft-versus-host disease (GVHD) (hazard ratio [HR] 1.72, p < 0.001 and HR 2.48, p < 0.001), non-relapse mortality (NRM) (HR 1.47, p < 0.001 and HR 2.00, p < 0.001), and overall survival (OS) (HR 1.21, p = 0.0066 and HR 1.60, p = 0.0015). Conversely, the use of ATG was an independent favorable factor for grade III-IV acute GVHD (HR 0.43, p < 0.001), NRM (HR 0.51, p < 0.001), and OS (HR 0.74, p = 0.0012). On the other hand, HLA compatibility and the use of ATG were not associated with a risk of relapse. An interaction test between the number of HLA mismatches and the use of ATG revealed that the effect of ATG on NRM and OS in the 2MMUD group was significantly less than that in the 1MMUD group (HR 1.53, p = 0.036 and HR 2.34, p = 0.0046). This study indicated that the number of HLA mismatches and the use of ATG were significantly associated with not only GVHD, but also NRM and OS. Whereas the use of ATG could improve transplant outcomes in allo-HCT from 1MMUD, its effectiveness with 2MMUD and 3MMUD was limited.

Risk factors associated with the development of moderate to severe chronic graft-versus-host disease after non-myeloablative conditioning allogeneic stem cell transplantation in patients with AML or MDS

Moderate to severe chronic graft-versus-host disease (cGVHD) is associated with high morbidity, hospital dependency and poor quality of life. In this study, we analyzed a well-defined consecutive series of 98 patients with acute myelogenous leukemia/myelodysplastic syndrome (AML/MDS) who received allogeneic stem cell transplantation with non-myeloablative (NMA) conditioning to determine risk factors associated with the severity of cGVHD. cGVHD was defined according to the 2005 National Institute of Health consensus criteria. Transfusions before transplantation, presence of HLA antibodies, composition of the graft (CD3+, CD19+, CD34+ cells), sibling or matched unrelated donor, female donor to male recipient, CMV serology and the development of acute GVHD (aGVHD), were considered potential risk factors. Multivariate Cox regression analysis identified the number of CD19+ 10⁶/kg (HR 2.79; 95% CI 1.35–5.74), CD3+ 10⁶/kg (HR 2.18; 95% CI 1.04–4.59) infused cells and the presence of patient HLA antibodies before transplantation (HR 2.34; CI 1.11–4.95) as significant risk factors for the development of moderate to severe cGVHD. In summary, we identified in a small, but well-defined cohort, 3 risk factors associated with the severity of cGVHD that should be validated in a larger multi-center study.

Thiotepa and antithymocyte globulin-based conditioning prior to haploidentical transplantation with posttransplant cyclophosphamide in high-risk hematological malignancies

We report results of a thiotepa-based conditioning in haploidentical stem cell transplantation (haplo-SCT) with posttransplant cyclophosphamide (PT-CY) and antithymocyte globulin (ATG), for unmanipulated peripheral blood stem cell (PBSC) transplants, in 80 patients with hematological malignancies. Patients in complete remission (CR) received a thiotepa-busulfan-fludarabine (TBF) regimen, while patients with relapsed/refractory (R/R) malignancies received a sequential regimen consisting of thiotepa-etoposide-cyclophosphamide (TEC) and reduced-intensity conditioning (RIC). The median age was 52 (range, 17-72) years, 44% patients had R/R disease at transplant, and the median follow-up was 417 (range, 180-1595) days. The median days to neutrophil engraftment was 17 (range, 12-34). The cumulative incidences (CI) of acute graft-versus-host disease (GVHD) grade III to IV, severe chronic GVHD, nonrelapse mortality (NRM), and relapse were 16%, 16%, 26, and 26%, respectively. The 2-year overall survival (OS) and disease-free survival (DFS) were 53% and 47%, respectively. There were no significant differences between the patients in CR and R/R patients in terms of engraftment, GVHD, NRM, relapse, OS, or DFS. We conclude that thiotepa-based regimen with PT-CY can be modified with PBSC and ATG, still providing low toxicity, protection against GVHD, and low relapse incidence. Particularly encouraging are the results with the modification to sequential regimen in R/R patients.

The MarrowMiner: A Novel Minimally Invasive and Effective Device for the Harvest of Bone Marrow

Bone marrow (BM) is a rich source of hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs), and other important stem/progenitor cells. It is the traditional source of cells used in hematopoietic cell transplantation, which is a proven curative treatment for many blood and immune diseases. BM-derived cells have also been shown to have other diverse clinical uses and are increasingly being used in orthopedic medicine, regenerative medicine, and gene therapy applications. Traditional methods for harvesting BM are crude, tedious, time-consuming, and expensive, requiring multiple bone punctures under general anesthesia with serial small-volume aspirates often diluted with peripheral blood. The MarrowMiner (MM) is a novel device designed for rapid and minimally invasive BM harvest. Here we show the safety and efficacy of the MM in both preclinical and clinical settings. In a large-animal porcine model, the MM enabled effective BM collection with similar total nucleated cell collection and increased colony formation compared with standard methods. The MM was subsequently evaluated in a clinical study showing effective and complication-free anterior and posterior BM collection of 20 patients under only local anesthesia or light sedation. Increased total nucleated and mononucleated cell collection was achieved with the MM compared with standard methods in the same patients. Importantly, stem cell content was high with trends toward increased HSC, MSC, and endothelial progenitor cells with similar T cell content. Given the MM is a novel device approved by the US Food and Drug Administration, enabling safe, effective, and minimally invasive harvest of BM, we anticipate rapid adoption for various applications.

Personalizing rabbit anti-thymocyte globulin therapy for prevention of graft-versus-host disease after allogeneic hematopoietic cell transplantation: is there an optimal dose?

The efficacy of anti-thymocyte globulin (ATG) as prophylaxis for graft-versus-host disease (GVHD) has been investigated by many clinical studies over the past decade, including some randomized controlled trials. Intriguingly, although ATG is commonly used as prophylaxis for GVHD, there is still controversy about the optimal dose of ATG for prophylaxis of GVHD after allogeneic hematopoietic cell transplantation (allo-HCT). Indeed, the dose and formulation of ATG, as well as the degree of clinical benefit, has varied among studies, which makes it difficult to fully determine the clinical benefit of ATG. The aim of this review is to summarize the information regarding the optimal ATG dose of each formulation according to stem cell source, and to discuss how best to determine the personalized optimal dose of ATG in each allo-HCT recipient.

Risk Factors for Transplant Outcomes in Children and Adolescents with Non-Malignant Diseases Following Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND The objective of this study was the analysis of transplant outcomes and survival in children treated with allogeneic hematopoietic cell transplantation (alloHCT) for non-malignant disorders, with a focus on risk factor analysis of transplant-related mortality (TRM). MATERIAL AND METHODS The treatment outcome was analyzed retrospectively in 10 consecutive years in 4 pediatric transplant centers in Poland. To compare the outcomes, patient data were analyzed according to the diagnosis, age at transplant, donor type, stem cell source, conditioning regimens, transplanted CD34+ cells dose, and pediatric TRM score. RESULTS From 183 analyzed patients, 27 (14.8%) died, all of them due to transplant-related complications. TRM occurred more frequently in matched unrelated donor (MUD) transplant recipients vs. matched sibling donor (MSD) transplant recipients (p=0.02); in peripheral blood (PB) recipients vs. bone marrow (BM) recipients (p=0.004); and in patients receiving >5×10⁶/kg CD34+ cells (p<0.0001). OS differed significantly according to underlying disease comparing to other diagnoses. Lower survival was found in patients transplanted from MUD (p=0.02). OS was higher in patients receiving BM (p=0.001) and in those receiving ≤5×10⁶/kg CD34+ cells (p<0.001). Multivariate analysis showed lower probability of TRM in BM recipients (p=0.04). The probability of TRM was higher in SCID patients (p=0.02) and in patients receiving >5×10⁶/kg CD34+ cells (p=0.0001). CONCLUSIONS Underlying disease, stem cell source, and CD34+ dose higher than 5×10⁶/kg were the most important risk factors for TRM, and they all affected OS.

Immune reconstitution following hematopoietic stem cell transplantation using different stem cell sources

Introduction: Adequate immune reconstitution post-HSCT is crucial for the success of transplantation, and can be affected by both patient- and transplant-related factors. Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses is performed to investigate immune recovery posttransplant. In this review, we discuss the pattern of immune recovery in the post-transplant period focusing on the impact of stem cell source (bone marrow, peripheral blood stem cells, and cord blood) on immune recovery and HSCT outcome. We examine the impact of serotherapy on immune reconstitution and the need to tailor dosing of serotherapy agents when using different stem cell sources. We discuss new techniques being used particularly with cord blood and haploidentical grafts to improve immune recovery in each scenario. Expert opinion: Cord blood T cells provide a unique CD4+ biased immune reconstitution. Initial studies using targeted serotherapy with cord grafts showed improved immune recovery with limited alloreactivity. Two competing haploidentical approaches have developed in recent years including TCRαβ/CD19 depleted grafts and post-cyclophosphamide haplo-HSCT. Both approaches have comparable survival rates with limited alloreactivity. However, delayed immune reconstitution is still an ongoing problem and could be improved by modified donor lymphocyte infusions from the same haploidentical donor.

Higher response rates in patients with severe chronic skin graft-versus-host disease treated with extracorporeal photopheresis

Introduction

Different forms of graft-versus-host disease (GVHD) remain a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). The prognosis for steroid-refractory chronic GVHD (cGVHD) remains poor. Our aim was to evaluate extracorporeal photopheresis (ECP) treatment in cGVHD patients with different organ involvement to detect subgroups of patients with the best response.

Material and methods

Thirty-four patients who underwent HSCT and developed moderate (n = 7) or severe (n = 27) steroid-refractory or steroid-dependent cGVHD treated with ECP were included in the analysis. A matched cGVHD control patient group untreated with ECP was collected for comparison.

Results

Compared to the control group and the stable/progressive disease (SD/PD) patients, individuals with complete/partial remission have higher overall survival and lower transplant-related mortality. Furthermore, patients with complete and partial remission (CR/PR) had significantly higher levels of albumin and platelets after ECP treatment compared to patients with stable or progressive cGVHD (SD/PD). Corticosteroid treatment and other immunosuppressive agents could successfully be tapered in the CR/PR group compared to the SD/PD patients. In this study patients with skin cGVHD are those with the highest rate of CR/PR after ECP treatment.

Conclusions

Our results suggest that ECP treatment is safe and effective for patients with predominantly skin, oral and liver cGVHD.

Complications of Stem Cell Transplantation that Affect Infections in Stem Cell Transplant Recipients, with Analogies to Patients with Hematologic Malignancies

This article discusses the complications of hematopoietic stem cell transplantion (HSCT) that affect infections in HSCT recipients, with analogies to patients with hematologic malignancies. Mucositis, with mucosal barrier disruption, is common and increases the risk of gram-positive and anaerobic bacterial, and fungal infections, and can evolve to typhlitis. Engraftment syndrome; graft-versus-host disease, hepatic sinusoidal obstruction syndrome; and posterior reversible encephalopathy syndrome can affect the infectious potential either directly from organ dysfunction or indirectly from specific treatment. Pulmonary infections can predispose to life threatening complications including diffuse alveolar hemorrhage, idiopathic pulmonary syndrome, bronchiolitis obliterans syndrome, and bronchiolitis obliterans with organizing pneumonia.

The Concentration of Total Nucleated Cells in Harvested Bone Marrow for Transplantation Has Decreased over Time

Bone marrow (BM) is an essential source of hematopoietic stem cell grafts for many allogeneic hematopoietic cell transplant (HCT) recipients, including adult patients (for specific diseases and transplantation strategies) and the majority of pediatric recipient. However, since the advent of granulocyte colony-stimulating factor-mobilized peripheral blood stem cell (PBSC) grafts, there has been a significant decrease in the use of BM in HCT, thought to be due mainly to the increased logistical challenges in harvesting BM compared with PBSCs, as well as generally no significant survival advantage of BM over PBSCs. The decreased frequency of collection has the potential to impact the quality of BM harvests. In this study, we examined >15,000 BM donations collected at National Marrow Donor Program centers between 1994 and 2016 and found a significant decline in the quality of BM products, as defined by the concentration of total nucleated cells (TNCs). The mean TNC concentration in BM donations dropped from 21.8 × 10⁶ cells/mL in the earliest era (1994 to 1996) to 18.7 × 10⁶ cells/mL in the most recent era (2012 to 2016) (means ratio, .83; P < .001). This decline in BM quality was seen despite the selection of more donors perceived to be optimal (eg, younger and male). Multivariate regression analysis showed that higher-volume centers (performing >30 collections per era) had better-quality harvests with higher concentrations of TNCs collected. In conclusion, we have identified a significant decrease in the quality of BM collections over time, and lower-volume collection centers had poorer-quality harvests. In this analysis, we could not elucidate the direct cause for this finding, suggesting the need for further studies to investigate the key factors responsible and to explore the impact on transplant recipients.

Peripheral Blood or Bone Marrow Stem Cells? Practical Considerations in Hematopoietic Stem Cell Transplantation

Although peripheral blood stem cells (PBSC) have worldwide become the predominant source of progenitor cells for hematopoietic stem cell transplantation (HSCT), debate about their role compared with bone marrow (BM) has recently intensified, in large part based on the results of a multicenter Clinical Trials Network study which showed lower incidence of chronic graft-versus-host disease (cGVHD) and improved quality of life in recipients of myeloablative HLA-matched unrelated BM compared with PBSC transplants. However, in certain patient populations, PBSC may lead to improved clinical outcomes due to faster hematologic recovery, a lower risk of graft failure, and possibly a lower probability of relapse. This review will provide a comprehensive summary of studies comparing PBSC with BM as the graft source in terms of acute and chronic GVHD incidence, time to engraftment, and disease-free and overall survival probabilities after HLA-matched related and unrelated donor transplantation and haploidentical donor transplantation. Recommendations based on these studies regarding the use of PBSC versus BM for HSCT are offered.

The case for plerixafor to replace filgrastim as the optimal agent to mobilize peripheral blood donors for allogeneic hematopoietic cell transplantation

Granulocyte colony-stimulating factor (G-CSF)-stimulated peripheral blood progenitor cells (G-PBs) from either a related or unrelated donor continue to be the preferred donor source for most allogeneic hematopoietic cell transplantation (HCT). Recently, the American Society for Blood and Marrow Transplantation has recommended marrow instead of G-PBs as an unrelated graft source due to its lower rate of chronic graft-versus-host disease (cGVHD). However, the use of marrow is limited by both clinical considerations (slower rate of engraftment and increased donor morbidity) and logistical considerations (use of operating room resources and increased physician utilization), so this recommendation has not been widely adopted. An optimal donor source would include the rapid engraftment characteristic and the low donor morbidity associated with G-PBs and a rate of cGVHD similar to or lower than that of marrow. Recent data suggest that plerixafor mobilized PBs (P-PBs) have the rapid engraftment characteristics of G-PBs in allogeneic HCT with less cGVHD. The biologic mechanism of the lower rate of cGVHD appears to be through mobilization of regulator natural killer cells and plasmacytoid dendritic cell precursors that are associated with lower acute and chronic GVHD compared with G-PBs and rapid engraftment characterized by rapid myeloid-repopulating capacity. We suggest that, based on the experience of the two Phase II clinical trials and the unique biology of plerixafor-mobilized donor product, it should be evaluated in Phase III trials as an approach to replacing G-CSF mobilization for allogeneic HCT.

Bone Marrow versus Peripheral Blood from Unrelated Donors for Children and Adolescents with Acute Leukemia

Graft-versus-host disease (GVHD) rates are higher after unrelated donor transplantation; thus, we examined whether there would be differences in transplant outcomes by graft type in children and adolescents with acute leukemia. The primary endpoint was overall survival. We studied 872 patients <18 years old who were transplanted with bone marrow (n = 650) or peripheral blood (n = 222) from unrelated donors. The characteristics of the 2 groups were comparable, except recipients of bone marrow were younger than recipients of peripheral blood (median age, 10 versus 12 years). Grades 2 to 4 (hazard ratio [HR], 1.48; P < .001) and grades 3 and 4 acute (HR, 1.69; P < .001) and chronic GVHD (HR, 1.92; P < .001) were higher with transplantation of peripheral blood than with bone marrow. Although relapse risks were lower after peripheral blood transplants (HR, 0.76; P = .05), transplant-related mortality (HR, 1.91; P = .003) and overall mortality (HR, 1.34; P = .032) were higher than with bone marrow transplants. The 8-year probability of overall survival after transplantation of bone marrow was 47% compared with 42% after peripheral blood. The 8-year probability of leukemia-free survival was 40% after transplantation of bone marrow and peripheral blood. Lower relapse after transplantation of peripheral blood negated the survival advantage after transplantation of bone marrow. The observed higher acute and chronic GVHD seen with peripheral blood suggest cautious use of this graft in children and adolescents with acute leukemia.

Translation of Clinical Research into Practice: An Impact Assessment of the Results from the Blood and Marrow Transplant Clinical Trials Network Protocol 0201 on Unrelated Graft Source Utilization

Barriers and facilitators to adoption of results of clinical trials are substantial and poorly understood. We sought to examine whether the results of the randomized, multicenter Blood and Marrow Transplant Clinical Trials Network (BMT CTN) 0201 study comparing peripheral blood (PB) with bone marrow (BM) stem cells for unrelated donor (URD) hematopoietic cell transplantation (HCT) changed practice from PB to BM graft utilization and explored factors that impact graft selection and translation of research results into practice. The difference between use of URD BM and PB in the 2 years before and after publication of results in 2012 was examined using observational data collected by the Center for Blood and Marrow Transplant Research. A web-based survey of transplant physicians was conducted to understand the change in physician-reported personal and center preferred URD graft. No significant change in use of BM versus PB grafts occurred after 2012. Both BMT CTN participating and nonparticipating centers continued to use PB. Ninety-two percent of respondents were aware of the study results; 18% reported a change in personal and 16% reported a change in their center's practice of requesting BM instead of PB for URD HCT. Patient characteristics and the perception that engaging local champions to increase the evidence uptake were factors associated with personal or center change in practice. Despite awareness of the trial results, fewer than one-fifth of HCT physicians reported practice change in response to the BMT CTN 0201 results. Observational data confirmed no discernible change in practice.

Transplant-related mortality and survival in children with malignancies treated with allogeneic hematopoietic stem cell transplantation. A multicenter analysis

The aim of the study was to assess the risk of TRM in pediatric patients treated for malignant disorders with allogeneic HSCT, according to different risk factors. The treatment outcome was analyzed in 299 pediatric patients treated in pediatric transplant departments from 2006 to 2015. To compare the outcome, patients were analyzed all together and in groups according to the diagnosis, age at transplant, donor type, disease status, stem cell source, and pediatric TRM score. At the end of the observation time, 82 patients were alive, 82 died, of which 40 due to transplant-related reasons. The most frequently observed causes of TRM were toxic complications effecting with organ failure (38%), followed by infections (26%), PTLD (14.3%), and GvHD (16.7%). There was no statistical difference in the incidence of TRM depending on stem cell source (P = .209) and primary diagnosis (P = .301). According to TRM score, TRM was significantly higher in high-risk group (P = .006). High-risk patients had lower survival comparing to low/intermediate group (P = .0001). OS did not differ between ALL, AML, and MDS/JMML groups. The study confirmed the utility of factors included in TRM score stratification in assessing the risk of transplant procedure in pediatric patients transplanted for malignancies.

Reduced intensity conditioning increases risk of severe cGVHD: identification of risk factors for cGVHD in a multicenter setting

Chronic graft-versus-host disease (cGVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Aim is to identify risk factors for the development of cGVHD in a multicenter setting. Patients transplanted between 2000 and 2006 were analyzed (n = 820). Donors were HLA-identical siblings (57%), matched unrelated donors (30%), and HLA-A, B or DR antigen mismatched (13%). Reduced intensity conditioning (RIC) was given to 65% of patients. Overall incidence of cGVHD was 46% for patients surviving more than 100 days after HSCT (n = 747). Older patient age [HR 1.15, p < 0.001], prior acute GVHD [1.30, p = 0.024], and RIC [1.36, p = 0.028] increased overall cGVHD. In addition, RIC [4.85, p < 0.001], prior aGVHD [2.14, p = 0.001] and female donor to male recipient [1.80, p = 0.008] increased the risk of severe cGVHD. ATG had a protective effect for both overall [0.41, p < 0.001] and severe cGVHD [0.20, p < 0.001]. Relapse-free survival (RFS) was impaired in patients with severe cGVHD. RIC, prior aGVHD, and female-to-male donation increase the risk of severe cGVHD. ATG reduces the risk of all grades of cGVHD without hampering RFS. GVHD prophylaxis may be tailored according to the risk profile of patients.

Grade II Acute Graft-versus-Host Disease and Higher Nucleated Cell Graft Dose Improve Progression-Free Survival after HLA-Haploidentical Transplant with Post-Transplant Cyclophosphamide

Compared with standard graft-versus-host disease (GVHD) prophylaxis platforms, post-transplantation cyclophosphamide (PTCy) after T cell-replete HLA-haploidentical (haplo) bone marrow transplantation (BMT) reduces the risk of grades III to IV acute (a) and chronic (c) GVHD, but maintains similar rates of grade II aGVHD. Given that mild GVHD has been associated with reduced treatment failure in HLA-matched BMT, we evaluated the risk factors for and effects of GVHD on survival in 340 adults with hematologic malignancies who engrafted after nonmyeloablative haplo-BMT with PTCy, mycophenolate mofetil, and tacrolimus. The cumulative incidence at 100 days of grade II and grades III to IV aGVHD were 30% (95% confidence interval [CI], 25% to 35%) and 2% (95% CI, 1% to 4%), respectively. The 1-year cumulative incidence of cGVHD was 10% (95% CI, 7% to 13%). In landmark analyses at 100 days, the 4-year probabilities of overall survival (OS) and progression-free survival (PFS) were, 48% (95% CI, 41% to 56%) and 39% (95% CI, 32% to 47%) for patients without grades II to IV aGVHD, compared with 63% (95% CI, 53% to 73%) and 59% (95% CI, 50% to 71%) for patients with grade II aGVHD (P = .05 and P = .009). In multivariable modeling, when compared with patients who never experienced GVHD, the hazard ratio (HR) for OS and PFS in patients with grade II aGVHD was .78 (95% CI, .54 to 1.13; P = .19) and .69 (95% CI, .48 to .98; P = .04). Higher nucleated cell graft dose was also associated with improved OS (HR, .88; 95% CI, .78 to 1.00; P = .05) and PFS (HR, .89; 95% CI, .79 to 1.0; P = .05) and decreased risk of grades III to IV aGVHD (subdistribution HR, .66; 95% CI, .46 to .96; P = .03). PTCy reduces grades III to IV aGVHD and cGVHD, but retains similar incidence of grade II aGVHD, the development of which improves PFS. Higher nucleated cell graft dose goals may also improve survival after nonmyeloablative haplo-BMT with PTCy.

CD56bright natural killer regulatory cells in filgrastim primed donor blood or marrow products regulate chronic graft-versus-host disease: the Canadian Blood and Marrow Transplant Group randomized 0601 study results

Randomized trials have conclusively shown higher rates of chronic graft-versus-host disease with filgrastim-stimulated apheresis peripheral blood as a donor source than unstimulated bone marrow. The Canadian Blood and Marrow Transplant Group conducted a phase 3 study of adults who received either filgrastim-stimulated apheresis peripheral blood or filgrastim-stimulated bone marrow from human leukocyte antigen-identical sibling donors. Because all donors received the identical filgrastim dosing schedule, this study allowed for a controlled evaluation of the impact of stem cell source on development of chronic graft-versus-host disease. One hundred and twenty-one evaluable filgrastim-stimulated apheresis peripheral blood and filgrastim-stimulated bone marrow patient donor products were immunologically characterized by flow cytometry and tested for their association with acute and chronic graft-versus-host disease within 2 years of transplantation. The immune populations evaluated included, regulatory T cells, central memory and effector T cells, interferon γ positive producing T cells, invariate natural killer T cells, regulatory natural killer cells, dendritic cell populations, macrophages, and activated B cells and memory B cells. When both filgrastim-stimulated apheresis peripheral blood and filgrastim-stimulated bone marrow were grouped together, a higher chronic graft-versus-host disease frequency was associated with lower proportions of CD56^bright natural killer regulatory cells and interferon γ-producing T helper cells in the donor product. Lower CD56^bright natural killer regulatory cells displayed differential impacts on the development of extensive chronic graft-versus-host disease between filgrastim-stimulated apheresis peripheral blood and filgrastim-stimulated bone marrow. In summary, while controlling for the potential impact of filgrastim on marrow, our studies demonstrated that CD56^bright natural killer regulatory cells had a much stronger impact on filgrastim-stimulated apheresis peripheral blood than on filgrastim-stimulated bone marrow. This supports the conclusion that a lower proportion of CD56^bright natural killer regulatory cells results in the high rate of chronic graft-versus-host disease seen in filgrastim-stimulated apheresis peripheral blood. clinicaltrials.gov Identifier: 00438958.

Age does not adversely influence outcomes among patients older than 60 years who undergo allogeneic hematopoietic stem cell transplant for AML and myelodysplastic syndrome

Allogeneic hematopoietic stem cell transplant (AHSCT) outcomes data of older AML/myelodysplastic syndrome (MDS) patients are limited. We retrospectively evaluated consecutive patients ⩾60 years old with AML/MDS who underwent AHSCT between January 2005 and December 2014. The primary objectives were to determine nonrelapse mortality (NRM), relapse, relapse-free survival (RFS) and overall survival (OS) at 1 year post AHSCT. A total of 159 patients underwent AHSCT with a median age of 64 (range, 60-75) years. Of these, 103 patients (65%) had AML and 56 patients (35%) had MDS. At 1 year post AHSCT, grade III-IV acute GvHD and chronic GvHD occurred in 20.8% (95% confidence interval (CI), 14.9-27.5%) and 54.1% (95% CI, 46.0-61.5%) of patients, respectively. NRM, RFS, relapse rate and OS at 1 year post AHSCT were 25.3% (95% CI, 18.8-32.3%), 53.3% (95% CI, 46.1-61.7%), 21.4% (95% CI, 15.4-28.1%) and 56.4% (95% CI, 49.2-54.7%), respectively. High disease risk index was associated with poor RFS, OS and higher relapse rate (P<0.03), whereas non-thymoglobulin-based GvHD prophylaxis, higher comorbidity index (⩾3) and MDS were associated with higher NRM (P<0.03). Importantly, age did not have an adverse effect on NRM, relapse, RFS and OS. AHSCT was well tolerated. Hence, older age alone should not be considered a contraindication to AHSCT.

Allogeneic Hematopoietic Cell Transplantation for Adult Chronic Myelomonocytic Leukemia

Allogeneic hematopoietic cell transplantation (HCT) is potentially curative for patients with chronic myelomonocytic leukemia (CMML); however, few data exist regarding prognostic factors and transplantation outcomes. We performed this retrospective study to identify prognostic factors for post-transplantation outcomes. The CMML-specific prognostic scoring system (CPSS) has been validated in subjects receiving nontransplantation therapy and was included in our study. From 2001 to 2012, 209 adult subjects who received HCT for CMML were reported to the Center for International Blood and Marrow Transplant Research. The median age at transplantation was 57 years (range, 23 to 74). Median follow-up was 51 months (range, 3 to 122). On multivariate analyses, CPSS scores, Karnofsky performance status (KPS), and graft source were significant predictors of survival (P = .004, P = .01, P = .01, respectively). Higher CPSS scores were not associated with disease-free survival, relapse, or transplantation-related mortality. In a restricted analysis of subjects with relapse after HCT, those with intermediate-2/high risk had a nearly 2-fold increased risk of death after relapse compared to those with low/intermediate-1 CPSS scores. Respective 1-year, 3-year, and 5-year survival rates for low/intermediate-1 risk subjects were 61% (95% confidence interval [CI], 52% to 72%), 48% (95% CI, 37% to 59%), and 44% (95% CI, 33% to 55%), and for intermediate-2/high risk subjects were 38% (95% CI, 28% to 49%), 32% (95% CI, 21% to 42%), and 19% (95% CI, 8% to 29%). We conclude that higher CPSS score at time of transplantation, lower KPS, and a bone marrow graft are associated with inferior survival after HCT. Further investigation of CMML disease-related biology may provide insights into other risk factors predictive of post-transplantation outcomes.

Role of myeloid-derived suppressor cells in allogeneic hematopoietic cell transplantation

Graft-versus-host disease (GVHD) can be a devastating complication for as many as a third of patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT). A role for myeloid cells in the amplification of GVHD has been demonstrated; however, less is understood about a potential regulatory role that myeloid cells play or whether such cells may be manipulated and applied therapeutically. Myeloid-derived suppressor cells (MDSCs) are a naturally occurring immune regulatory population that are engaged and expand shortly after many forms of immune distress, including cancer, trauma, and infection. As MDSCs are often associated with chronic disease, inflammation, and even the promotion of tumor growth (regarding angiogenesis/metastasis), they can appear to be predictors of poor outcomes and therefore, vilified; yet, this association doesn't match with their perceived function of suppressing inflammation. Here, we explore the role of MDSC in GVHD in an attempt to investigate potential synergies that may be promoted, leading to better patient outcomes after allo-HCT.

Safety and efficacy of allogeneic hematopoietic stem cell transplant after PD-1 blockade in relapsed/refractory lymphoma

Anti-programmed cell death protein 1 (PD-1) monoclonal antibodies are being increasingly tested in patients with advanced lymphoma. Following treatment, many of those patients are likely to be candidates for allogeneic hematopoietic stem cell transplant (HSCT). However, the safety and efficacy of HSCT may be affected by prior PD-1 blockade. We conducted an international retrospective analysis of 39 patients with lymphoma who received prior treatment with a PD-1 inhibitor, at a median time of 62 days (7-260) before HSCT. After a median follow-up of 12 months, the 1-year cumulative incidences of grade 2-4 and grade 3-4 acute graft-versus-host disease (GVHD) were 44% and 23%, respectively, whereas the 1-year incidence of chronic GVHD was 41%. There were 4 treatment-related deaths (1 from hepatic sinusoidal obstruction syndrome, 3 from early acute GVHD). In addition, 7 patients developed a noninfectious febrile syndrome shortly after transplant requiring prolonged courses of steroids. One-year overall and progression-free survival rates were 89% (95% confidence interval [CI], 74-96) and 76% (95% CI, 56-87), respectively. One-year cumulative incidences of relapse and nonrelapse mortality were 14% (95% CI, 4-29) and 11% (95% CI, 3-23), respectively. Circulating lymphocyte subsets were analyzed in 17 patients. Compared with controls, patients previously treated with PD-1 blockade had significantly decreased PD-1⁺ T cells and decreased ratios of T-regulatory cells to conventional CD4 and CD8 T cells. In conclusion, HSCT after PD-1 blockade appears feasible with a low rate of relapse. However, there may be an increased risk of early immune toxicity, which could reflect long-lasting immune alterations triggered by prior PD-1 blockade.

CD25 Blockade Delays Regulatory T Cell Reconstitution and Does Not Prevent Graft-versus-Host Disease After Allogeneic Hematopoietic Cell Transplantation

Daclizumab, a humanized monoclonal antibody, binds CD25 and blocks formation of the IL-2 receptor on T cells. A study of daclizumab as acute graft-versus-host disease (GVHD) prophylaxis after unrelated bone marrow transplantation was conducted before the importance of CD25⁺FOXP3⁺ regulatory T cells (Tregs) was recognized. Tregs can abrogate the onset of GVHD. The relation between Tregs and a graft-versus-malignancy effect is not fully understood. An international, multicenter, double-blind clinical trial randomized 210 adult or pediatric patients to receive 5 weekly doses of daclizumab at 0.3 mg/kg (n = 69) or 1.2 mg/kg (n = 76) or placebo (n = 65) after unrelated marrow transplantation for treatment of hematologic malignancies or severe aplastic anemia. The risk of acute GVHD did not differ among the groups (P = .68). Long-term follow-up of clinical outcomes and correlative analysis of peripheral blood T cell phenotype suggested that the patients treated with daclizumab had an increased risk of chronic GVHD (hazard ratio [HR], 1.49; 95% confidence interval [CI], 1.0 to 2.3; P = .08) and a decreased risk of relapse (HR, 0.57; 95% CI, 0.3 to 1.0; P = .05), but similar survival (HR, 0.89; 95% CI, 0.6 to 1.3; P = .53). T cells from a subset of patients (n = 107) were analyzed by flow cytometry. Compared with placebo, treatment with daclizumab decreased the proportion of Tregs among CD4 T cells at days 11-35 and increased the proportion of central memory cells among CD4 T cells at 1 year. Prophylactic administration of daclizumab does not prevent acute GVHD, but may increase the risk of chronic GVHD and decrease the risk of relapse. By delaying Treg reconstitution and promoting immunologic memory, anti-CD25 therapy may augment alloreactivity and antitumor immunity.

NK cell effector functions in a Chédiak-Higashi patient undergoing cord blood transplantation: Effects of in vitro treatment with IL-2

NK cell cytotoxicity in Chédiak-Higashi syndrome (CHS) is strongly impaired as lytic granules are not released upon NK-target cell contact, contributing to several defects typical of this severe immunodeficiency. Correction of NK cell defects in CHS should improve the outcome of hematopoietic stem-cell transplantation, proposed as therapy. We investigated NK cell functions in a CHS patient before and after cord-blood transplantation, and the ability of in vitro IL-2 treatment to restore them. Before the transplant, the strong defect in NK cell-mediated natural and antibody-dependent cytotoxicity, as well as in IFN-γ production, could be restored up to normal levels by in vitro IL-2 treatment. This cytokine also caused the appearance of smaller lysosomal granules and their orientation towards the NK-target cell contact area, thus suggesting that IL-2 had a more general capacity to restore NK cell effector functions. Moreover after the transplant, although the successful engraftment, NK cell cytotoxicity resulted still partially impaired at one year, almost normal at ten years and, anyhow, fully recovered by in vitro IL-2 treatment. Taken together, our results indicate that IL-2 had a wide capacity to restore NK cell effector functions, being able to reverse the altered cytotoxic activity, lytic granule pattern, and cytokine production observed in the CHS patient.

Comparison of graft-versus-host disease-free, relapse-free survival according to a variety of graft sources: antithymocyte globulin and single cord blood provide favorable outcomes in some subgroups

Graft-versus-host disease-free relapse-free survival, which is defined as the absence of grade III-IV acute graft-versus-host disease, systemically treated chronic graft-versus-host disease, relapse, and death, is a novel, meaningful composite end point for clinical trials. To characterize risk factors and differences in graft-versus-host disease-free relapse-free survival according to a variety of graft sources, we analyzed 23,302 patients with hematologic malignancy that had a first allogeneic transplantation from 2000 through 2013 using the Japanese national transplant registry database. The 1-year graft-versus-host disease-free relapse-free survival rate was 41% in all patients. The rate was higher after bone marrow transplantation than after peripheral blood stem cell transplantation due to the lower risks of III-IV acute and chronic graft-versus-host disease. The rate was highest after HLA-matched sibling bone marrow transplantation. The rate after single cord blood transplantation was comparable to that after HLA-matched unrelated bone marrow transplantation among patients aged 20 years or under, and was comparable or better than other alternative graft sources among patients aged 21 years or over, due to the low risk of chronic graft-versus-host disease. Other factors associated with better graft-versus-host disease-free relapse-free survival include female patients, antithymocyte globulin prophylaxis (for standard-risk disease), recent years of transplantation, sex combinations other than from a female donor to a male patient, the absence of prior autologous transplantation, myeloablative conditioning, negative cytomegalovirus serostatus, and tacrolimus-based prophylaxis. These results provide important information to guide the choice of graft sources and are benchmarks for future graft-versus-host disease prophylaxis studies.

Practice Patterns and Preferences Among Hematopoietic Cell Transplantation Clinicians

Hematopoietic cell transplantation can cure many high-risk diseases but is associated with complexity, cost, and risk. Several areas in transplantation practice were identified in the 2014 Blood and Marrow Transplant Clinical Trials Network State of the Science Symposium (BMT CTN SOSS) as high priorities for further study. We developed a survey for hematopoietic cell transplantation clinicians to identify current practices in BMT CTN SOSS priority areas and to understand, more generally, the variation in approach to transplantation and estimation of transplantation benefit in current medical practice. Of 1439 transplantation clinicians surveyed, 305 responded (20% response rate). Clinicians were well represented by age, experience, geography, and size of practice. We found that several techniques identified in the BMT CTN SOSS, such as maintenance therapy for acute myeloid leukemia or myelodysplastic syndromes after allogeneic transplantation, were already being utilized in practice on and off study, with higher rates of use in higher-volume centers. There was significant variation among clinicians in use of transplantation technologies and approaches to common transplantation scenarios. Appraisals of risks and benefits of transplantation appeared to converge upon similar estimates despite the presentation of different hypothetical scenarios. These results suggest overall equipoise in several BMT CTN SOSS high-priority areas and support the need for better data to inform clinical practice.

Haploidentical transplantation in children with unmanipulated peripheral blood stem cell graft: The need to look beyond post-transplantation cyclophosphamide in younger children

Haploidentical transplantation with PTCY following marrow or PBSC graft has been associated with low incidence of GVHD in adults with similar data lacking in children. We report on the outcome of 25 patients <20 yr of age (median age 12 yr), undergoing a haploidentical PBSC transplantation for both malignant and non-malignant disorders. Engraftment was prompt and sustained. Cumulative incidences of acute GVHD and chronic GVHD were 40.3% and 16.7%, respectively. On subgroup analysis, it was evident that acute GVHD developed in 80% of patients <10 yr compared to only 13.3% in those between 10 and 20 yr [log-rank p = 0.001], despite similar graft composition with significantly higher NRM (60% vs. 0%; p = 0.001). The FFS was 63.5%; (79% in >10 yr and 40% in <10 yr, p = 0.01). Our data suggest that PTCY-based haploidentical PBSC transplantation is feasible in older children, but results in early and severe alloreactivity in younger children. These findings, despite being counterintuitive, could be explained by the variable metabolism of CY and oral mycophenolate in younger children indicating that PTCY-based approach as used in adults might not be adequate for younger children.

Risk Factors and Outcome of Chronic Graft-versus-Host Disease after Allogeneic Stem Cell Transplantation-Results from a Single-Center Observational Study

Chronic graft versus host disease (cGVHD) is the most frequent long-term complication after allogeneic stem cell transplantation (allo-SCT) and results in impaired quality of life and increased long-term morbidity and mortality. We analyzed 243 patients with cGVHD, documented according to the 2005 revised National Institutes of Health consensus criteria, to identify risk factors for the occurrence of cGVHD and outcomes for the patients with cGVHD. Patients without evidence of cGVHD (n = 147) were used as controls. Performing univariate and multivariate Cox regression analyses, we identified prior acute GVHD grades III or IV (hazard ratio [HR], 2.01; P = .005), use of peripheral blood stem cell graft (HR, 2.10; P = .03), and HLA-mismatched allo-SCT from unrelated donor (HR, 1.57; P = .02) as independent risk factors for cGVHD. Performing Kaplan-Meier analyses, progressive compared with de novo and quiescent onset of cGVHD and a platelet count of less than 100/nL compared with more than 100/nL at the time of cGVHD onset were associated with a significantly increased cumulative incidence of transplantation-related mortality (TRM) and significantly decreased overall survival. Furthermore, we found a significantly higher incidence of TRM in patients with severe cGVHD compared with patients without cGVHD (58% versus 11%, P < .0001). However, in subgroup analysis, patients with severe cGVHD and involvement of the lung, liver, or gastrointestinal (GI) tract had a 6.5-fold significantly higher incidence of TRM (72%), whereas patients with severe cGVHD lacking lung, liver, or GI involvement had only a 2.8-fold significantly higher incidence of TRM (31%) compared with patients without cGVHD (11%; P < .0001 and P = .03). Patients without lung, liver, or GI involvement did not have a significantly different TRM compared with patients with moderate cGVHD (31% versus 25%, P = .52). In conclusion, we confirm prior known risk factors for the occurrence of cGVHD and subsequent mortality and we provide evidence that the presence of lung, liver, or GI involvement in patients with severe cGVHD defines a subgroup with high mortality after allo-SCT; however, in the absence of these risk factors, the outcome appears not to be impaired compared with moderate cGVHD.

Optimal graft source for allogeneic hematopoietic stem cell transplant: bone marrow or peripheral blood?

Peripheral blood (PB), compared with bone marrow graft, has higher stem cell content, leads to faster engraftment and is more convenient for collection. Consequently, the use of PB graft has significantly increased in recent years. Although the use of PB graft is acceptable or even preferred to bone marrow graft in matched related donor allogeneic transplant due to a possibility of improved survival, PB graft increases the risk of chronic graft-versus-host disease and associated long-term toxicities in the setting of matched unrelated donor allogeneic transplant. In haploidentical transplant, mitigation of graft-versus-host disease with the use of post-transplant cyclophosphamide is a hypothesis-generating possibility; however, available studies have significant limitations to draw any definite conclusion.

Late Acute Graft-versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation

There are little data regarding the incidence, clinical manifestations, risk factors, and outcomes of late acute graft-versus-host disease (aGVHD). We evaluated patients with late aGVHD after allogeneic hematopoietic cell transplantation (HCT) between 2007 and 2012 and compared their outcomes to patients with early-onset aGVHD. Of the 511 allogeneic HCT recipients, 75 developed late aGVHD (cumulative incidence: 14.7% (95% confidence interval [CI], 11.6% to 17.8%) versus 248 with early-onset aGVHD (cumulative incidence: 49% [95% CI, 45% to 53%]). Among those with late aGVHD, 52% had persistent, 39% had recurrent, and 9% had de novo late aGVHD. Advanced (grades III and IV) early-onset aGVHD was associated with a higher risk of developing late aGVHD (hazard ratio [HR], 1.9; 95% CI, 1.2 to 3.1; P = .01). Forty-eight percent (95% CI, 36% to 60%) of late aGVHD versus only 31% (95% CI, 26% to 37%) of early-onset aGVHD progressed to chronic GVHD by 2 years. Higher proportion of persistent (53%) as compared to recurrent (39%) and de novo (46%) late aGVHD progressed to cGVHD at 2 years. The overall survival was 59% (95% CI, 49% to 72%) in late aGVHD and 50% (95% CI, 44% to 57%) in early-onset aGVHD. Persistent late aGVHD had worse overall survival and nonrelapse mortality (45% and 39%, respectively) than recurrent (74% and 18%, respectively) and de novo (83% and 0%, respectively) late aGVHD. Compared with HLA-identical sibling HCT, unrelated donor transplantations were associated with a higher risk of mortality in patients developing late aGVHD (HR, 6.1; 95% CI, 2.3 to 16.2; P < .01). In a landmark analysis (evaluating 100-day survivors among early-onset aGVHD), no difference was seen in late mortality (after 100 days) between early-onset and late aGVHD (HR, .96; 95% CI, .59 to 1.55; P = .85); however, the risk of cGVHD was nearly doubled (HR, 1.81; 95% CI, 1.16 to 2.82; P = .01) in patients with late aGVHD. Late aGVHD is a relatively common complication after allogeneic HCT. Poorer outcomes in those with persistent late aGVHD imply need for more effective therapy in this group to improve transplantation outcomes. A higher risk of subsequent chronic GVHD needs further evaluation and close monitoring.

Mismatched unrelated alternative donors for hematological malignancies

For the majority of hematologic malignancies allogeneic hematopoietic cell transplantation (HCT) is the only curative treatment option. Sibling donors have been the standard for adult patients. Since there is not a suitable family donor for all patients, the need for alternative donors for HCT is great. Fortunately, the availability of unrelated volunteer donor registries has expanded over the years and the results of HCT with matched unrelated donors (MUD) are comparable to the results with matched related donors (MRD). Nevertheless, there are many patients lacking a well-matched donor. To increase the applicability of transplantation, alternative donors such as mismatched unrelated donors (MMURD), cord blood stem cell products and haploidentical related donors have been widely used. This review seeks to give insights into the use of MMUD donors for HCT and summarize the existing data.

Reduced-intensity transplantation for lymphomas using haploidentical related donors vs HLA-matched unrelated donors

We evaluated 917 adult lymphoma patients who received haploidentical (n = 185) or HLA-matched unrelated donor (URD) transplantation either with (n = 241) or without antithymocyte globulin (ATG; n = 491) following reduced-intensity conditioning regimens. Haploidentical recipients received posttransplant cyclophosphamide-based graft-versus-host disease (GVHD) prophylaxis, whereas URD recipients received calcineurin inhibitor-based prophylaxis. Median follow-up of survivors was 3 years. The 100-day cumulative incidence of grade III-IV acute GVHD on univariate analysis was 8%, 12%, and 17% in the haploidentical, URD without ATG, and URD with ATG groups, respectively (P = .44). Corresponding 1-year rates of chronic GVHD on univariate analysis were 13%, 51%, and 33%, respectively (P < .001). On multivariate analysis, grade III-IV acute GVHD was higher in URD without ATG (P = .001), as well as URD with ATG (P = .01), relative to haploidentical transplants. Similarly, relative to haploidentical transplants, risk of chronic GVHD was higher in URD without ATG and URD with ATG (P < .0001). Cumulative incidence of relapse/progression at 3 years was 36%, 28%, and 36% in the haploidentical, URD without ATG, and URD with ATG groups, respectively (P = .07). Corresponding 3-year overall survival (OS) was 60%, 62%, and 50% in the 3 groups, respectively, with multivariate analysis showing no survival difference between URD without ATG (P = .21) or URD with ATG (P = .16), relative to haploidentical transplants. Multivariate analysis showed no difference between the 3 groups in terms of nonrelapse mortality (NRM), relapse/progression, and progression-free survival (PFS). These data suggest that reduced-intensity conditioning haploidentical transplantation with posttransplant cyclophosphamide does not compromise early survival outcomes compared with matched URD transplantation, and is associated with significantly reduced risk of chronic GVHD.

The hematopoietic system in the context of regenerative medicine

Hematopoietic stem cells (HSC) represent the prototype stem cell within the body. Since their discovery, HSC have been the focus of intensive research, and have proven invaluable clinically to restore hematopoiesis following inadvertent radiation exposure and following radio/chemotherapy to eliminate hematologic tumors. While they were originally discovered in the bone marrow, HSC can also be isolated from umbilical cord blood and can be "mobilized" peripheral blood, making them readily available in relatively large quantities. While their ability to repopulate the entire hematopoietic system would already guarantee HSC a valuable place in regenerative medicine, the finding that hematopoietic chimerism can induce immunological tolerance to solid organs and correct autoimmune diseases has dramatically broadened their clinical utility. The demonstration that these cells, through a variety of mechanisms, can also promote repair/regeneration of non-hematopoietic tissues as diverse as liver, heart, and brain has further increased their clinical value. The goal of this review is to provide the reader with a brief glimpse into the remarkable potential HSC possess, and to highlight their tremendous value as therapeutics in regenerative medicine.

Comparison of Characteristics and Outcomes of Trial Participants and Nonparticipants: Example of Blood and Marrow Transplant Clinical Trials Network 0201 Trial

Controversy surrounds the question of whether clinical trial participants have better outcomes than comparable patients who are not treated on a trial. We explored this question using a recent large, randomized, multicenter study comparing peripheral blood (PB) with bone marrow transplantation from unrelated donors, conducted by the Blood and Marrow Transplant Clinical Trials Network (BMT CTN). We compared characteristics and outcomes of study participants (n = 494) and nonparticipants (n = 1384) who appeared eligible and received similar treatment without enrolling on the BMT CTN trial at participating centers during the study time period. Data were obtained from the Center for International Blood and Marrow Transplant Research. Outcomes were compared between the 2 groups using Cox proportional hazards regression models. No significant differences in age, sex, disease distribution, race/ethnicity, HLA matching, comorbidities, and interval from diagnosis to hematopoietic cell transplantation were seen between the participants and nonparticipants. Nonparticipants were more likely to have lower performance status, lower risk disease, and older donors, and to receive myeloablative conditioning and antithymocyte globulin. Nonparticipants were also more likely to receive PB grafts, the intervention tested in the trial (66% versus 50%, P < .001). Overall survival, transplantation-related mortality, and incidences of acute or chronic graft-versus-host disease were comparable between the 2 groups though relapse was higher (hazard ratio, 1.22; 95% confidence interval, 1.02 to 1.46; P = .028) in nonparticipants. Despite differences in certain baseline characteristics, survival was comparable between study participants and nonparticipants. The results of the BMT CTN trial appear generalizable to the population of trial-eligible patients.