Cord Blood Transplantation from Unrelated Donors in Adults with High-Risk Acute Myeloid Leukemia

Single vs double umbilical cord blood transplantation in acute leukemia: Systematic review and meta-analysis

BACKGROUND AND AIMS

Umbilical cord blood transplantation (UCBT) has emerged as a promising treatment option for patients with acute leukemia needing hematopoietic stem cell transplantation. Both single (sUCBT) and double cord blood units (dUCBT) demonstrate potential benefits, but studies comparing their effectiveness have shown mixed results. This meta-analysis aimed to determine the comparative safety and efficacy of sUCBT versus dUCBT in acute leukemia patients.

METHODS

Electronic databases were systematically examined to identify relevant studies comparing single vs double UCBT published until November 2023. Nine studies involving 3864 acute leukemia patients undergoing UCBT were included. Outcomes analyzed were acute graft-versus-host disease (GVHD), chronic GVHD, relapse, non-relapse mortality, leukemia-free survival and overall survival. Pooled risk ratios (RR) with 95% confidence intervals (CI) were calculated using a random effects model.

RESULTS

The risk of Grade II-IV acute GVHD (RR 1.55, 95% CI 1.19-2.03) and Grade III-IV acute GVHD (RR 1.25, 95% CI 1.07-1.46) were significantly higher with dUCBT. Relapse risk was lower with dUCBT (RR 0.57, 95% CI 0.38-0.88) while overall survival favored sUCBT (RR 1.25, 95% CI 1.06-1.46). No significant differences were observed for chronic GVHD, non-relapse mortality or leukemia-free survival.

CONCLUSION

Both single and double UCBT have potential as effective treatments for acute leukemia. The choice of treatment should consider various factors, including the risk of GVHD, relapse, and mortality. More research, especially randomized trials, is needed to provide definitive guidance on the optimal use of single and double unit UCBT in patients with acute leukemia.

Umbilical cord blood transplantation: Still growing and improving

Umbilical cord blood transplantation (UCBT) has been performed in the clinic for over 30 years. The biological and immunological characteristics of umbilical cord blood (UCB) have been re-recognized in recent years. UCB, previously considered medical waste, is rich in hematopoietic stem cells (HSCs), which are naïve and more energetic and more easily expanded than other stem cells. UCB has been identified as a reliable source of HSCs for allogeneic hematopoietic stem cell transplantation (allo-HSCT). UCBT has several advantages over other methods, including no harm to mothers and donors, an off-the-shelf product for urgent use, less stringent HLA match, lower incidence and severity of chronic graft-vs-host disease (GVHD), and probably a stronger graft-vs-leukemia effect, especially for minimal residual disease-positive patients before transplant. Recent studies have shown that the outcome of UCBT has been improved and is comparable to other types of allo-HSCT. Currently, UCBT is widely used in malignant, nonmalignant, hematological, congenital and metabolic diseases. The number of UCB banks and transplantation procedures increased exponentially before 2013. However, the number of UCBTs increased steadily in Asia and China but decreased in the United States and Europe year-on-year from 2013 to 2019. In this review, we focus on the development of UCBT over the past 30 years, the challenges it faces and the strategies for future improvement, including increasing UCB numbers, cord blood unit selection, conditioning regimens and GVHD prophylaxis for UCBT, and management of complications of UCBT.

Allogeneic hematopoietic cell transplantation with cord blood versus mismatched unrelated donor with post-transplant cyclophosphamide in acute myeloid leukemia

BACKGROUND

Allogeneic hematopoietic cell transplantation (allo-HCT) using a mismatched unrelated donor (MMUD) and cord blood transplantation (CBT) are valid alternatives for patients without a fully human leukocyte antigen (HLA)-matched donor. Here, we compared the allo-HCT outcomes of CBT versus single-allele-mismatched MMUD allo-HCT with post-transplant cyclophosphamide (PTCy) in acute myeloid leukemia.

METHODS

Patients who underwent a first CBT without PTCy (N = 902) or allo-HCT from a (HLA 9/10) MMUD with PTCy (N = 280) were included in the study. A multivariate regression analysis was performed for the whole population. A matched-pair analysis was carried out by propensity score-based 1:1 matching of patients (177 pairs) with known cytogenetic risk.

RESULTS

The incidence of grade II-IV and grade III-IV acute graft-versus-host disease (GVHD) at 6 months was 36% versus 32% (p = 0.07) and 15% versus 11% (p = 0.16) for CBT and MMUD cohorts, respectively. CBT was associated with a higher incidence of graft failure (11% vs. 4%, p < 0.01) and higher 2-year non-relapse mortality (NRM) (30% vs. 16%, p < 0.01) compared to MMUD. In the multivariate analysis, CBT was associated with a higher risk of, NRM (HR = 2.09, 95% CI 1.46-2.99, p < 0.0001), and relapse (HR = 1.35, 95% CI 1-1.83, p = 0.05), which resulted in worse leukemia-free survival (LFS) (HR = 1.68, 95% CI 1.34-2.12, p < 0.0001), overall survival (OS) (HR = 1.7, 95% CI 1.33-2.17, p < 0.0001), and GVHD-free, relapse-free survival (GRFS) (HR = 1.49, 95% CI 1.21-1.83, p < 0.0001) compared to MMUD. The risk of grade II-IV acute GVHD (p = 0.052) and chronic GVHD (p = 0.69) did not differ significantly between the cohorts. These results were confirmed in a matched-pair analysis.

CONCLUSIONS

CBT was associated with lower LFS, OS, and GRFS due to higher NRM, compared to MMUD allo-HCT with PTCy. In the absence of a fully matched donor, 9/10 MMUD with PTCy may be preferred over CBT.

Optimizing Transplant Approaches and Post-Transplant Strategies for Patients With Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) is the commonest indication for allogeneic stem cell transplantation (allo-SCT) worldwide. The increasingly important role of allo-SCT in the management of AML has been underpinned by two important advances. Firstly, improvements in disease risk stratification utilizing genetic and Measurable Residual Disease (MRD) technologies permit ever more accurate identification of allo-mandatory patients who are at high risk of relapse if treated by chemotherapy alone. Secondly, increased donor availability coupled with the advent of reduced intensity conditioning (RIC) regimens has substantially expanded transplant access for patients with high risk AML In patients allografted for AML disease relapse continues to represent the commonest cause of transplant failure and the development of novel strategies with the potential to reduce disease recurrence represents a major unmet need.

Guidelines for Cord Blood Unit Selection

Optimal cord blood (CB) unit selection is critical to maximize the likelihood of successful engraftment and survival after CB transplantation (CBT). However, unit selection can be complex because multiple characteristics must be considered including unit cell dose, donor-recipient human leukocyte antigen (HLA) match, and unit quality. This review provides evidence-based and experience-based comprehensive guidelines for CB unit selection. Topics addressed include the use of both the TNC and the CD34⁺ cell dose, as well as the CD34⁺ cell to TNC content ratio to evaluate unit progenitor cell content and engraftment potential, the acceptable TNC and CD34⁺ cell dose criteria that define an adequate single-unit graft, and the indication and acceptable cell dose criteria for double-unit grafts. The acceptable criteria for 6-loci (HLA-A, -B antigen, -DRB1 allele) and 8-allele (HLA-A, -B, -C, -DRB1) donor-recipient HLA match, the evaluation of patients with donor-specific HLA antibodies, and the multiple determinants of unit quality are also reviewed in detail. Finally, a practical step-by-step guide to CB searches and the principles that guide ultimate graft selection are outlined.

CD34+ cell content of 126 341 cord blood units in the US inventory: implications for transplantation and banking

CD34⁺ cell dose is critical for cord blood (CB) engraftment. However, the CD34⁺ content of the CB inventory in the United States is unknown. We examined the CD34⁺ cell content of 126 341 red blood cell-depleted US units banked from January 2007 to September 2017 with a total nucleated cell (TNC) count of ≥90 × 10⁷ and a cryovolume of 24-55 mL. Median pre-cryopreservation TNC content was 127 × 10⁷ (interquartile range [IQR], 108-156 × 10⁷); CD34⁺ cell content was 44 × 10⁵ (IQR, 29 to 67 × 10⁵). The median CD34⁺:TNC ratio was 0.34%. TNC and CD34⁺ cell content correlation was weak (r = 0.24). Of 7125 units with TNCs of ≥210 × 10⁷, only 47% had CD34⁺ content of ≥100 × 10⁵ However, some units had high CD34⁺ content for a given TNC count. Only 4% of CB units were acceptable as single-unit grafts (TNCs, ≥2.5 × 10⁷/kg; CD34⁺ cells, ≥1.5 × 10⁵/kg) for 70-kg patients; 22% of units were adequate for 70-kg patients using lower dose criteria (TNCs, ≥1.5 × 10⁷/kg; CD34⁺ cells, ≥1.0 × 10⁵/kg) suitable for a double-unit graft. These findings highlight that units with the highest TNC dose may not have the highest CD34⁺ dose, units with unexpectedly high CD34⁺ content (a ratio of >1.0%) should be verified, and the US CB inventory of adequately sized single units for larger patients is small. They also support the ongoing use of double-unit grafts, a focus on banking high-dose units, and development of expansion technologies.

Impact of Adding Antithymocyte Globulin to Posttransplantation Cyclophosphamide in Haploidentical Stem-Cell Transplantation

BACKGROUND

Graft-versus-host disease (GVHD) is a major cause of mortality after allogeneic stem-cell transplantation. Posttransplantation cyclophosphamide (PT/CY) has become standard prophylaxis of GVHD in T-replete haploidentical transplantation. The question is whether adding antithymocyte globulin (ATG) to PT/CY may further reduce the incidence of GVHD compared to PT/CY only.

PATIENTS AND METHODS

We retrospectively studied 268 patients undergoing myeloablative haploidentical transplantation with thiotepa, busulfan, and fludarabine (TBF) conditioning. Sixty-nine patients (26%) received ATG.

RESULTS

In the ATG group, 3% died due to GVHD versus 8% in the no ATG group. The 100-day and 1-year nonrelapse mortality (NRM) was 0% and 19%, respectively, in the whole cohort. On univariate analysis, the 1-year NRM was 8% versus 23% in patients receiving ATG and no ATG, respectively (P = .005). The no ATG group had a higher incidence of acute GVHD at 12 months compared to the ATG group (22% vs. 12%, respectively, P = .029). The ATG group had better overall survival at 12 months compared to the no ATG group (79% vs. 69%, P = .029). On multivariate analysis, adding ATG to PT/CY had no significant impact on any of the outcomes. A low disease risk index was associated with better overall survival and lower NRM, while Hematopoietic Cell Transplantation-Specific Comorbidity Index (HCT-CI) score ≥ 3 was associated with higher NRM.

CONCLUSION

ATG can be safely used as part of the pretransplantation conditioning and does not increase the incidence of relapse or complications after transplantation.

Effect of the Thiotepa Dose in the TBF Conditioning Regimen in Patients Undergoing Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia in Complete Remission: A Report From the EBMT Acute Leukemia Working Party

BACKGROUND

Allogeneic stem cell transplantation is a potentially curative therapy for patients with acute myeloid leukemia (AML) after achieving complete remission (CR). The aim of this study is to evaluate the optimal dose of thiotepa, administered as part of the thiotepa-busulfan-fludarabine (TBF) conditioning regimen for allogeneic stem cell transplantation in adults with AML in CR.

PATIENTS AND METHODS

In a retrospective multicenter analysis, we identified 240 patients allotransplanted from matched related or unrelated donors or T replete haplo-identical donors. We compared the transplantation outcomes of patients who received 5 mg/kg thiotepa and 2 days of intravenous busulfan at 6.4 mg/kg (T1B2F) versus those who received 10 mg/kg thiotepa with 2 days of intravenous busulfan at 6.4 mg/kg (T2B2F). The median follow-up was 20 months.

RESULTS

On univariate analysis, the incidence of acute graft versus host disease (GVHD) grade II to IV was significantly lower in the T1B2F group (19%) versus 32% in the T2B2F group (P = .029). This result was confirmed on multivariate analysis; acute GVHD was higher for patients receiving T2B2F (hazard ratio, 2.22; P = .024). No significant change in non-relapse mortality, progression-free survival, or overall survival was observed between the 2 groups.

CONCLUSION

T2B2F is associated with a higher incidence of acute GVHD compared with T1B2F. These results suggest that a lower dose-intensity of thiotepa and busulfan in the TBF regimen may yield better results in patients with AML in CR.

Evaluation of post-thaw CFU-GM: clinical utility and role in quality assessment of umbilical cord blood in patients receiving single unit transplant

BACKGROUND

The CFU assay is considered the only in vitro assay that assesses the biologic function of hematopoietic stem and progenitor cells (HSPC).

STUDY DESIGN AND METHODS

To investigate the impact of post-thaw CFU-GM counts on the quality of umbilical cord blood (UCB), we studied transplant outcomes in 269 patients receiving single UCB transplant. We also correlated the post-thaw CFU-GM counts of 1912 units with the pre-freeze and post-thaw graft characteristics, hoping to optimize selection criteria of UCB. Data analysis included: total nucleated cells, viability, CD34+, nucleated red blood cells (NRBC), hematocrit, frozen storage time, and cord blood bank (CBB).

RESULTS

We demonstrated an association between post-thaw CFU-GM dose and the speed of neutrophil and platelet engraftment (p < 0.01). Higher post-thaw CFU-GM dose showed an increased benefit for neutrophil and platelet engraftment (p < 0.01). Post-thaw CD34+ cell dose and CFU-GM dose were strongly correlated (r = 0.78). However, CFU-GM dose showed additional benefit for patients receiving the lowest quartile of CD34+ dose. HLA disparity did not adversely impact either neutrophil or platelet engraftment. Post-thaw CFU-GM/million nucleated cells plated showed moderate correlation with pre-freeze and post-thaw CD34+ and weak correlation with other parameters. Post-thaw CFU-GM was not influenced by storage time, but was impacted by the CBB from which the unit is obtained (p < 0.01).

CONCLUSION

Post-thaw CFU-GM is an effective measure of the quality and efficacy of the UCB graft, particularly adding valuable clinical information when the CD34+ cell dose is low. Consideration of pre-freeze CD34+ cell content and CBB as additional selection criteria is warranted.

Fludarabine-treosulfan compared to thiotepa-busulfan-fludarabine or FLAMSA as conditioning regimen for patients with primary refractory or relapsed acute myeloid leukemia: a study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

Background

Limited data is available to guide the choice of the conditioning regimen for patients with acute myeloid leukemia (AML) undergoing transplant with persistent disease.

Methods

We retrospectively compared outcome of fludarabine-treosulfan (FT), thiotepa-busulfan-fludarabine (TBF), and sequential fludarabine, intermediate dose Ara-C, amsacrine, total body irradiation/busulfan, cyclophosphamide (FLAMSA) conditioning in patients with refractory or relapsed AML.

Results

Complete remission rates at day 100 were 92%, 80%, and 88% for FT, TBF, and FLAMSA, respectively (p = 0.13). Non-relapse mortality, incidence of relapse, acute (a) and chronic (c) graft-versus-host disease (GVHD) rates did not differ between the three groups. Overall survival at 2 years was 37% for FT, 24% for TBF, and 34% for FLAMSA (p = 0.10). Independent prognostic factors for survival were Karnofsky performance score and patient CMV serology (p = 0.01; p = 0.02), while survival was not affected by age at transplant. The use of anti-thymocyte globulin (ATG) was associated with reduced risk of grade III–IV aGVHD (p = 0.02) and cGVHD (p = 0.006), with no influence on relapse.

Conclusions

In conclusion, FT, TBF, and FLAMSA regimens provided similar outcome in patients undergoing transplant with active AML. Survival was determined by patient characteristics as Karnofsky performance score and CMV serology, however was not affected by age at transplant. ATG appears able to reduce the incidence of acute and chronic GVHD without influencing relapse risk.

Electronic supplementary material

The online version of this article (10.1186/s13045-019-0727-4) contains supplementary material, which is available to authorized users.

Thiotepa, busulfan and fludarabine compared to busulfan and cyclophosphamide as conditioning regimen for allogeneic stem cell transplant from matched siblings and unrelated donors for acute myeloid leukemia

Busulfan plus cyclophosphamide (BuCy) is the traditional conditioning regimen for allogeneic stem cell transplant (allo-SCT) for young, fit patients with acute myeloid leukemia (AML). The thiotepa-busulfan-fludarabine (TBF) protocol has recently demonstrated promising outcome in cord blood and haploidentical SCT; however, there is limited evidence about this regimen in transplant from matched siblings (MSD) and unrelated donors (UD). We retrospectively compared outcomes of 2523 patients aged 18-50 with AML in remission, undergoing transplant from MSD or UD prepared with either TBF or BuCy conditioning. A 1:3 pair-matched analysis was performed: 146 patients receiving TBF were compared with 438 patients receiving BuCy. Relapse risk was significantly lower in the TBF when compared with BuCy group (HR 0.6, P = .02), while NRM did not differ. No significant difference was observed in LFS and OS between the two regimens. TBF was associated with a trend towards higher risk of grades III-IV aGVHD (HR 1.8, P = .06) and inferior cGVHD (HR 0.7, P = .04) when compared with BuCy. In patients undergoing transplant in first remission, the advantage for TBF in terms of relapse was more evident (HR 0.4, P = .02), leading to a trend for better LFS in favor of TBF (HR 0.7, P = .10), while OS did not differ between the two cohorts. In conclusion, TBF represents a valid myeloablative conditioning regimen providing significantly lower relapse and similar survival when compared with BuCy. Patients in first remission appear to gain the most from this protocol, as in this subgroup a tendency for better LFS was observed when compared with BuCy.

Thiotepa-busulfan-fludarabine compared to busulfan-fludarabine for sibling and unrelated donor transplant in acute myeloid leukemia in first remission

Background

A preparatory regimen consisting of thiotepa-busulfan-fludarabine (TBF) has been associated with reduced relapse in patients with haematological malignancies after haploidentical and cord blood transplants; however, few data exist regarding TBF conditioning in sibling (MSD) and unrelated donor (URD) transplants for AML.

Results

Among patients receiving a myeloablative (MAC) regimen, TBF-MAC was associated with significantly lower relapse (HR 0.47, p = 0.005) however higher non-relapse mortality (NRM, HR 2.69, p < 10^–4) as compared to BF. This led to similar leukemia-free (LFS) and overall survival (OS) between the two regimens (LFS: p = 0.6; OS: p = 0.27). When we selected TBF-MAC patients receiving busulfan 9.6 mg/kg, NRM resulted still higher but no more significantly different as compared to BF-MAC with busulfan 12.8 mg/kg (HR 1.53, p = 0.12); despite the lower busulfan dose, relapse remained inferior with TBF-MAC (HR 0.45, p = 0.01), however no difference in survival could be demonstrated (LFS: p = 0.31; OS: 0.82). Among patients receiving a reduced-intensity (RIC) regimen, similar outcome was observed with TBF-RIC and BF-RIC (LFS: p = 0.77; OS: p = 0.88).

Conclusions

TBF-MAC as conditioning regimen for transplant from MSD and URD in AML patients in first remission provided stronger anti-leukemic activity but higher NRM as compared to BF-MAC, thus leading to similar survival. TBF-MAC with busulfan 9.6 mg/kg was associated with low relapse and acceptable NRM, however again with no survival benefit. TBF-RIC and BF-RIC resulted in comparable outcome.

Methods

We conducted a registry-based study comparing outcomes of patients with AML in first remission undergoing transplant from MSD or URD prepared with either TBF (n = 212) or BF (n = 2698) conditioning.

Single-agent GvHD prophylaxis with tacrolimus after post-transplant high-dose cyclophosphamide is a valid option for haploidentical transplantation in adults with hematological malignancies

Eighty-one patients with high-risk hematological malignancies received unmanipulated haploidentical stem cell transplants (haploSCT) using the same protocol at four Spanish institutions. The conditioning regimen was thiotepa, busulfan and fludarabine; following bone marrow or peripheral blood infusion. GvHD prophylaxis with high-dose cyclophosphamide on days +3 and +4, and IV tacrolimus from day +5 was administered. 62% were in complete remission, 17% had received previous allogeneic SCT and 44% had a high-very high refined disease risk index. One patient had primary graft failure and three more died before +21. The median days to neutrophil and platelet recoveries were +18 and +23, respectively, and 93% achieved a full donor chimerism on day +30. At 1 year, cumulative incidences (CumInc) of non-relapse mortality and relapse were 27 and 19%. One-year overall survival and PFS were 61 and 51%. CumInc of grade II-IV and III-IV were 23 and 14%. At 30 months, CumInc of limited and extensive GvHD were 20 and 22%. In conclusion, patients with hematological malignancies who receive an unmanipulated haploSCT with post-transplant cyclophosphamide may benefit from less intense pharmacological prophylaxis for GvHD prophylaxis. Whether this approach potentiates the graft-versus-tumor effect and decreases relapses requires further investigation.

New drugs and allogeneic hematopoietic stem cell transplantation for hematological malignancies: do they have a role in bridging, consolidating or conditioning transplantation treatment?

INTRODUCTION

Novel targeted therapies and monoclonal antibodies can be combined with allogeneic stem cell transplantation (allo-SCT) at different time-points: 1) before the transplant to reduce tumour burden, 2) as part of the conditioning in place of or in addition to conventional agents 3) after the transplant to allow long-term disease control. Areas covered: This review focuses on the current integration of new drugs with allo-SCT for the treatment of major hematological malignancies for which allo-SCT has been a widely-adopted therapy. Expert opinion: After having been used as single agent salvage treatments in relapsed patients after allo-SCT or in combination with donor lymphocyte infusions, many new drugs have also been safely employed before allo-SCT as a bridge to transplantation or after it as planned consolidation/maintenance. This era of new drugs has opened new important opportunities to 'smartly' combine 'targeted drugs and cell therapies' in new treatment paradigms that may lead to higher cure rates or longer disease control in patients with hematological malignancies.

The effect of inter-unit HLA matching in double umbilical cord blood transplantation for acute leukemia

The effects of inter-unit HLA-match on early outcomes with regards to double cord blood transplantation have not been established. Therefore, we studied the effect of inter-unit HLA-mismatching on the outcomes of 449 patients with acute leukemia after double cord blood transplantation. Patients were divided into two groups: one group that included transplantations with inter-unit mismatch at 2 or less HLA-loci (n=381) and the other group with inter-unit mismatch at 3 or 4 HLA-loci (n=68). HLA-match considered low resolution matching at HLA-A and -B loci and allele-level at HLA-DRB1, the accepted standard for selecting units for double cord blood transplants. Patients', disease, and transplant characteristics were similar in the two groups. We observed no effect of the degree of inter-unit HLA-mismatch on neutrophil (Hazard Ratio 1.27, P=0.11) or platelet (Hazard Ratio 0.1.13, P=0.42) recovery, acute graft-versus-host disease (Hazard Ratio 1.17, P=0.36), treatment-related mortality (Hazard Ratio 0.92, P=0.75), relapse (Hazard Ratio 1.18, P=0.49), treatment failure (Hazard Ratio 0.99, P=0.98), or overall survival (Hazard Ratio 0.98, P=0.91). There were no differences in the proportion of transplants with engraftment of both units by three months (5% after transplantation of units with inter-unit mismatch at ≤2 HLA-loci and 4% after transplantation of units with inter-unit mismatch at 3 or 4 HLA-loci). Our observations support the elimination of inter-unit HLA-mismatch criterion when selecting cord blood units in favor of optimizing selection based on individual unit characteristics.

Thiotepa-based conditioning for allogeneic stem cell transplantation in acute lymphoblastic leukemia-A survey from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

In this study, we analyzed a thiotepa-based conditioning regimen for allogeneic stem cell transplantation in adults with acute lymphoblastic leukemia, using the EBMT database. A total of 323 patients were identified. The median age was 43 years. Disease status at transplant was first complete remission (CR1) in 48.9%, CR2 in 21.7%, CR3 in 6.2%, while 23.2% of the patients had an active disease at the time of transplant. This was performed from a HLA-matched sibling (49.8%) or a matched-unrelated donor (51.2%). The incidence of acute graft-vs.-host disease (GvHD) (grade > II) was 26.6%, while chronic GvHD occurred in 35.9% of the patients at 1 year (24.6% with extensive disease). With a median follow-up of 16.8 months, the nonrelapse mortality was 12.4 and 25.3% at 100 days and 1 year, respectively. The relapse incidence at 1 year was 33.3% with no difference for patients in CR1 (27%). The one-year leukemia-free survival (LFS) and overall survival (OS) were 57 and 66%, respectively for the entire cohort and 50 and 66%, respectively in patients in CR1. Thiotepa/busulfan ± melphalan (n = 213) in comparison to thiotepa/other (n = 110) conditioning regimen resulted in higher relapse incidence at 1 year (34.9 vs. 30.3%, P = 0.016) and lower LFS (38.8 vs. 45.9%, P = 0.0203), while nonrelapse mortality (23.8 vs. 26.3%, n.s.) and OS (59.6 vs. 51.1%, P = 0.109) did not differ. This large study suggests that a thiotepa-based conditioning for allogeneic transplantation in acute lymphoblastic leukemia is feasible and effective, with the main outcomes being comparable to those achieved with other regimens. Am. J. Hematol. 92:18-22, 2017. © 2016 Wiley Periodicals, Inc.

Erythropoietin modulation is associated with improved homing and engraftment after umbilical cord blood transplantation

Umbilical cord blood (UCB) engraftment is in part limited by graft cell dose, generally one log less than that of bone marrow (BM)/peripheral blood (PB) cell grafts. Strategies toward increasing hematopoietic stem/progenitor cell (HSPC) homing to BM have been assessed to improve UCB engraftment. Despite recent progress, a complete understanding of how HSPC homing and engraftment are regulated is still elusive. We provide evidence that blocking erythropoietin (EPO)-EPO receptor (R) signaling promotes homing to BM and early engraftment of UCB CD34+ cells. A significant population of UCB CD34+ HSPC expresses cell surface EPOR. Exposure of UCB CD34+ HSPC to EPO inhibits their migration and enhances erythroid differentiation. This migratory inhibitory effect was reversed by depleting EPOR expression on HSPC. Moreover, systemic reduction in EPO levels by hyperbaric oxygen (HBO) used in a preclinical mouse model and in a pilot clinical trial promoted homing of transplanted UCB CD34+ HSPC to BM. Such a systemic reduction of EPO in the host enhanced myeloid differentiation and improved BM homing of UCB CD34+ cells, an effect that was overcome with exogenous EPO administration. Of clinical relevance, HBO therapy before human UCB transplantation was well-tolerated and resulted in transient reduction in EPO with encouraging engraftment rates and kinetics. Our studies indicate that systemic reduction of EPO levels in the host or blocking EPO-EPOR signaling may be an effective strategy to improve BM homing and engraftment after allogeneic UCB transplantation. This clinical trial was registered at www.ClinicalTrials.gov (#NCT02099266).

Safety and efficacy of thiotepa-based conditioning for allogeneic transplantation in AML: a survey from the ALWP of the EBMT

This study evaluated the safety and efficacy of thiotepa-based regimens before allogeneic stem cell transplantation in 310 adult patients with AML. Disease status at the time of transplantation was CR1 in 50%, CR2+ in 23.5% and advanced disease in 26.5%. Transplantation was performed from haploidentical (35%), matched sibling (27%), unrelated (20%) or cord blood (18%) donors. As for safety: mucositis occurred in 46.8% of the patients and the cumulative incidence (CI) of sinusoidal obstruction syndrome was 4.0%. With a median follow-up of 37 months, the CI of acute GvHD grade>II was 26.5%, whereas CI of chronic GvHD was 28.1% at 3 years. CI for non-relapse mortality at 3 years was 38.4%, 49.7% and 45.4% for patients in CR1, CR2+ and advanced disease, respectively (P=0.10). Relapse incidence at 3 years was 20.2, 30.7 and 40.6% in these three respective groups (P=0.002). CI for 3-year leukemia-free survival and overall survival were 41.4% and 45.6% (CR1), 19.6% and 27.7% (CR2+), and 13.9% and 13.6% (advanced disease), respectively (P<10^-4 for both). Our data suggest that thiotepa-based conditioning therapy in AML is feasible, effective and safe, as investigated for sinusoidal obstruction syndrome and mucositis.

Antithymocyte globulin in allogeneic hematopoietic cell transplantation: benefits and limitations

Significant advances have been made in allogeneic hematopoietic cell transplantation by reducing toxicities and optimizing its efficacy. Antithymocyte globulin (ATG) is an important in vivo T-cell depletion strategy, which reduces the risk of graft-versus-host disease in HLA-matched or -mismatched donor allografting. ATG effectively targets alloreactive T cells at the expense of potentially increasing the risk of post-hematopoietic cell transplantation infections and delayed immune reconstitution. We summarize the targets, mechanisms, various preparations of ATG, the growing role of ATG in prevention of graft-versus-host disease in various transplant modalities as well as emerging data on pharmacokinetic modeling for individualized ATG dosing. Further research is needed to optimize the ATG administration while minimizing the toxicities.

Frequency and Risk Factors Associated with Cord Graft Failure after Transplant with Single-Unit Umbilical Cord Cells Supplemented by Haploidentical Cells with Reduced-Intensity Conditioning

Delayed engraftment and cord graft failure (CGF) are serious complications after unrelated cord blood (UCB) hematopoietic stem cell transplantation (HSCT), particularly when using low-cell-dose UCB units. The haplo-cord HSCT approach allows the use of a lower dose single UCB unit by co-infusion of a CD34(+) selected haploidentical graft, which provides early transient engraftment while awaiting durable UCB engraftment. We describe the frequency, complications, and risk factors of CGF after reduced-intensity conditioning haplo-cord HSCT. Among 107 patients who underwent haplo-cord HSCT, 94 were assessable for CGF, defined as <5% cord blood chimerism at day 60 in the myeloid and CD3 compartments, irrespective of neutrophil and platelet counts. CGF occurred in 14 of 94 assessable patients (15%). Median survival after CGF was 12.7 months with haploidentical or mixed haploidentical-autologous hematopoiesis persisting in the 7 surviving. Median progression-free survival after CGF was 7.7 months and was not statistically different from those without CGF (10.47 months; P = .18). In univariate analyses, no UCB factors were associated with CGF, including cell dose, cell viability, recipient major ABO mismatch against the UCB unit, or degree of HLA match. We also found no association of CGF with recipient cytomegalovirus serostatus, haploidentical donor age, or day 30 haploidentical chimerism. However, higher haploidentical total nucleated and CD34(+) cell doses and day 30 UCB chimerism < 5% in either the myeloid or CD3 compartments were associated with greater risk of CGF. We conclude that assessing chimerism at day 30 may foretell impending CGF, and avoidance of high haploidentical cell doses may reduce risk of CGF after haplo-cord HSCT. However, long-term survival is possible after CGF because of predominant haploidentical or mixed chimerism and hematopoietic function.

Reduced intensity haplo plus single cord transplant compared to double cord transplant: improved engraftment and graft-versus-host disease-free, relapse-free survival

Umbilical cord blood stem cell transplants are commonly used in adults lacking HLA-identical donors. Delays in hematopoietic recovery contribute to mortality and morbidity. To hasten recovery, we used co-infusion of progenitor cells from a partially matched related donor and from an umbilical cord blood graft (haplo-cord transplant). Here we compared the outcomes of haplo-cord and double-cord transplants. A total of 97 adults underwent reduced intensity conditioning followed by haplo-cord transplant and 193 patients received reduced intensity conditioning followed by double umbilical cord blood transplantation. Patients in the haplo-cord group were more often from minority groups and had more advanced malignancy. Haplo-cord recipients received fludarabine-melphalan-anti-thymocyte globulin. Double umbilical cord blood recipients received fludarabine-cyclophosphamide and low-dose total body irradiation. In a multivariate analysis, haplo-cord had faster neutrophil (HR=1.42, P=0.007) and platelet (HR=2.54, P<0.0001) recovery, lower risk of grade II-IV acute graft-versus-host disease (HR=0.26, P<0.0001) and chronic graft-versus-host disease (HR=0.06, P<0.0001). Haplo-cord was associated with decreased risk of relapse (HR 0.48, P=0.001). Graft-versus-host disease-free, relapse-free survival was superior with haplo-cord (HR 0.63, P=0.002) but not overall survival (HR=0.97, P=0.85). Haplo-cord transplantation using fludarabine-melphalan-thymoglobulin conditioning hastens hematopoietic recovery with a lower risk of relapse relative to double umbilical cord blood transplantation using the commonly used fludarabine-cyclophosphamide-low-dose total body irradiation conditioning. Graft-versus-host disease-free and relapse-free survival is significantly improved. Haplo-cord is a readily available graft source that improves outcomes and access to transplant for those lacking HLA-matched donors. Trials registered at clinicaltrials.gov identifiers 00943800 and 01810588.

Unrelated bone marrow transplantation or immediate umbilical cord blood transplantation for patients with acute myeloid leukemia in first complete remission

BACKGROUND

While unrelated bone marrow transplantation (UBMT) has been widely used as alternative donor transplantation, the use of umbilical cord blood transplantation (UCBT) is increasing recently.

METHODS

We conducted a decision analysis to address which transplantation procedure should be prioritized for younger patients with acute myeloid leukemia (AML) harboring high- or intermediate-risk cytogenetics in first complete remission (CR1), when they lack a matched related donor but have immediate access to a suitable umbilical cord blood unit. Main sources for our analysis comprised the data from three phase III trials for a chemotherapy cohort (n = 907) and the registry data for a transplantation cohort (n = 752).

RESULTS

The baseline analysis showed that when the 8/8 match was considered for UBMT, the expected 5-year survival rate was higher for UBMT than for UCBT (58.1% vs. 51.8%). This ranking did not change even when the 7/8 match was considered for UBMT. Sensitivity analysis showed consistent superiority of UBMT over UCBT when the time elapsed between CR1 and UBMT was varied within a plausible range of 3-9 months.

CONCLUSIONS

These results suggest that 8/8 or 7/8 UBMT is a better transplantation option than UCBT even after allowing time required for donor coordination.

[Efficacy analysis of unrelated cord blood transplantation for 58 acute myelogenous leukemia patients]

目的

探讨非血缘脐血移植(UCBT)治疗急性髓系白血病(AML)的疗效及影响疗效的相关因素。

方法

回顾性分析接受UCBT治疗58例AML患者的临床资料。中位年龄14.5(3~36)岁，中位体重45(12~90) kg。FAB分型：M₀ 1例、M₁ 1例、M₂ 35例(包括骨髓增生异常综合征转AML 1例)、M₄ 3例、M₅ 14例、M₆ 3例、混合细胞白血病1例。移植时处于第1次完全缓解期(CR₁)36例，第2次完全缓解期(CR₂)14例，未缓解(NR) 8例，其中高危难治患者43例(74.1%)。单份UCBT 49例(84.5%)，双份UCBT 9例(15.5%)。所有患者均采用强化清髓预处理方案，采用环孢素联合霉酚酸酯预防移植物抗宿主病(GVHD)。

结果

全部58例患者中56例(96.6%)获得造血重建，中性粒细胞植入、血小板植入的中位时间分别为17(12~37) d、33(17~140) d。24例(42.9%)患者发生急性GVHD，其中Ⅱ~Ⅳ度急性GVHD的发生率为30.4%(17/56)。在可评估的49例患者中，7例(14.3%)出现慢性GVHD(均为局限型)。预期3年累积总体生存(OS)率和无病生存(DFS)率分别为(60.3±6.4)％和(60.1±6.5)%。3年非复发死亡率为33.3%，复发率为9.1%。UCBT时疾病为CR患者(50例)的3年OS率高于NR患者(8例)[(66.0±6.7)％对(25.0±15.3)%，P=0.013]。

结论

UCBT治疗AML安全有效，慢性GVHD发生率和复发率较低。

Infections after T-replete haploidentical transplantation and high-dose cyclophosphamide as graft-versus-host disease prophylaxis

BACKGROUND

Recently, a platform of T-cell replete haploidentical hematopoietic stem cell transplantation (haplo-HSCT) using post-transplant cyclophosphamide (Cy) has shown high reproducibility and acceptable safety profile.

METHOD

This prospective cohort analysis allowed us to collect data on infections among 70 consecutive recipients of haplo-HSCT affected by various hematologic malignancies.

RESULTS

After a median follow-up of 23 months, cumulative incidence of viral infections was 70% (95% confidence interval [CI] 59-81) at 100 days and 77% (95% CI 67-87) at 1 year; 35 of 65 patients at risk had CMV reactivation (54%) and the rate of polyomavirus-virus-associated cystitis was 19% (13/70). Cumulative incidence of bacterial and fungal infections at 1 year were 63% (95% CI 51-75) and 12% (95% CI 4-19), respectively. Of note, only 1 invasive fungal infection occurred beyond 1 year after transplant (day +739).

CONCLUSION

In conclusion, despite a high rate of viral infections in the early period, present data suggest a satisfactory infectious profile after T-cell replete haplo-HSCT using post-transplant Cy. These results may help clinicians to improve both prophylactic and therapeutic antimicrobial strategies in this emerging haploidentical setting.

Alternative Donor Transplantation for Acute Myeloid Leukemia

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapy for adult patients with acute myeloid leukemia (AML), but its use for consolidation therapy after first remission with induction chemotherapy used to be limited to younger patients and those with suitable donors. The median age of AML diagnosis is in the late 60s. With the introduction of reduced-intensity conditioning (RIC), many older adults are now eligible to receive allo-HCT, including those who are medically less fit to receive myeloablative conditioning. Furthermore, AML patients commonly have no human leukocyte antigen (HLA)-identical or medically suitable sibling donor available to proceed with allo-HCT. Technical advances in donor matching, suppression of alloreactivity, and supportive care have made it possible to use alternative donors, such as unrelated umbilical cord blood (UCB) and partially HLA-matched related (haploidentical) donors. Outcomes after alternative donor allo-HCT are now approaching the outcomes observed for conventional allo-HCT with matched related and unrelated donors. Thus, with both UCB and haploidentical donors available, lack of donor should rarely be a limiting factor in offering an allo-HCT to adults with AML.

Thiotepa-based versus total body irradiation-based myeloablative conditioning prior to allogeneic stem cell transplantation for acute myeloid leukaemia in first complete remission: a retrospective analysis from the Acute Leukemia Working Party of the European Group for Blood and Marrow Transplantation

Thiotepa is an alkylating compound with an antineoplastic and myeloablative activity and can mimic the effect of radiation. However, it is unknown whether this new regimen could safely replace the long-established ones. This retrospective matched-pair analysis evaluated the outcome of adults with acute myeloid leukaemia in first complete remission who received myeloablative conditioning either with a thiotepa-based (n = 121) or a cyclophosphamide/total body irradiation-based (TBI; n = 358) regimen for allogeneic hematopoietic stem cell transplantation from an HLA-matched sibling or an unrelated donor. With a median follow-up of 44 months, the outcome was similar in both groups. Acute graft-versus-host disease grade II-IV was observed in 25% after thiotepa-containing regimen versus 35% after TBI (P = 0.06). The 2-yr cumulative incidence of chronic graft-versus-host disease was 40.5% for thiotepa and 41% for TBI (P = 0.98). At 2 yrs, the cumulative incidences of non-relapse mortality and relapse incidence were 23.9% (thiotepa) vs. 22.4% (TBI; P = 0.66) and 17.2% (thiotepa) vs. 23.3% (TBI; P = 0.77), respectively. The probabilities of leukaemia-free and overall survival at 2 yrs were not significantly different between the thiotepa and TBI groups, at 58.9% vs. 54.2% (P = 0.95) and 61.4% vs. 58% (P = 0.72), respectively. Myeloablative regimens using combinations including thiotepa can provide satisfactory outcomes, but the optimal conditioning remains unclear for the individual patient in this setting.

Salvaged single-unit cord blood transplantation for 26 patients with hematologic malignancies not in remission

Treatments for patients with hematologic malignancies not in remission are limited, but a few clinical studies have investigated the effects of salvaged unrelated cord blood transplantation (CBT). We retrospectively studied 19 patients with acute leukemia, 5 with myelodysplastic syndrome (MDS with refractory anemia with excess blasts [RAEB]), and 2 with non-Hodgkin's lymphoma who received 1 CBT unit ≤2 loci human leukocyte antigen (HLA)-mismatched after undergoing myeloablative conditioning regimens between July 2005 and July 2014. All of them were in non-remission before transplantation. The infused total nucleated cell (TNC) dose was 4.07 (range 2.76-6.02)×10⁷/kg and that of CD34⁺ stem cells was 2.08 (range 0.99-8.65)×10⁵/kg. All patients were engrafted with neutrophils that exceeded 0.5×10⁹/L on median day +17 (range 14-37 days) and had platelet counts of >20×10⁹/L on median day +35 (range 17-70 days). Sixteen patients (61.5%) experienced pre-engraftment syndrome (PES), and six (23.1%) patients progressed to acute graft-versus-host disease (GVHD). The cumulative incidence rates of II-IV acute GVHD and chronic GVHD were 50% and 26.9%, respectively. After a median follow-up of 27 months (range 5-74), 14 patients survived and 3 relapsed. The estimated 2-year overall survival (OS), disease-free survival (DFS), and non-relapse mortality (NRM) rates were 50.5%, 40.3%, and 35.2%, respectively. Salvaged CBT might be a promising modality for treating hematologic malignancies, even in patients with a high leukemia burden.

General and Virus-Specific Immune Cell Reconstitution after Double Cord Blood Transplantation

Cord blood transplantation (CBT) is curative for many patients with hematologic malignancies but is associated with delayed immune recovery and an increased risk of viral infections compared with HLA-matched bone marrow or peripheral blood progenitor cell transplantation. In this study we evaluated the significance of lymphocyte recovery in 125 consecutive patients with hematologic malignancies who underwent double-unit CBT (DUCBT) with an antithymocyte globulin-containing regimen at our institution. A subset of 65 patients was prospectively evaluated for recovery of T, natural killer (NK), and B cells, and in 46 patients we also examined viral-specific T cell recovery against adenovirus, Epstein-Barr virus, cytomegalovirus, BK virus, respiratory syncytial virus, and influenza antigen. Our results indicate that in recipients of DUCBT, the day 30 absolute lymphocyte count is highly predictive of nonrelapse mortality and overall survival. Immune recovery post-DUCBT was characterized by prolonged CD8+ and CD4+ T lymphopenia associated with preferential expansion of B and NK cells. We also observed profound delays in quantitative and functional recovery of viral-specific CD4+ and CD8+ T cell responses for the first year post-CBT. Taken together, our data support efforts aimed at optimizing viral-specific T cell recovery to improve outcomes post-CBT.

Dominant unit CD34+ cell dose predicts engraftment after double-unit cord blood transplantation and is influenced by bank practice

We investigated the unit characteristics associated with engraftment after double-unit cord blood (CB) transplantation (dCBT) and whether these could be reliably identified during unit selection. Cumulative incidence of neutrophil engraftment in 129 myeloablative dCBT recipients was 95% (95% confidence interval: 90-98%). When precryopreservation characteristics were analyzed, the dominant unit CD34(+) cell dose was the only characteristic independently associated with engraftment (hazard ratio, 1.43; P = .002). When postthaw characteristics were also included, only dominant unit infused viable CD34(+) cell dose independently predicted engraftment (hazard ratio, 1.95; P < .001). We then examined the determinants of infused viable CD34(+) cell dose (precryopreservation count, postthaw recovery, and postthaw viability) in 402 units thawed at our center. This revealed close correlation between precryopreservation and postthaw CD34(+) cell counts (r(2) = 0.73). Median CD34(+) cell recovery was 101%, although it ranged from 12% to 1480%. Notably, units from non-Netcord Foundation for the Accreditation of Cellular Therapy (Netcord-FACT)-accredited banks were more likely to have low recovery (P < .001). Furthermore, although median postthaw CD34(+) cell viability was 92%, 33 (8%) units had <75% viable CD34(+) cells. Units from non-Netcord-FACT-accredited banks and units with cryovolumes other than 24.5 to 26.0 mL were more likely to have poor postthaw viability. Precryopreservation CD34(+) cell dose and banking practices should be incorporated into CB unit selection.

Hematopoietic stem cell transplantation donor sources in the 21st century: choosing the ideal donor when a perfect match does not exist

Most patients who require allogeneic stem cell transplantation do not have a matched sibling donor, and many patients do not have a matched unrelated donor. In an effort to increase the applicability of transplantation, alternative donors such as mismatched adult unrelated donors, haploidentical related donors, and umbilical cord blood stem cell products are frequently used when a well matched donor is unavailable. We do not yet have the benefit of randomized trials comparing alternative donor stem cell sources to inform the choice of donor; however, the existing data allow some inferences to be made on the basis of existing observational and phase 2 studies. All 3 alternative donor sources can provide effective lymphohematopoietic reconstitution, but time to engraftment, graft failure rate, graft-versus-host disease, transplant-related mortality, and relapse risk vary by donor source. These factors all contribute to survival outcomes and an understanding of them should help guide clinicians when choosing among alternative donor sources when a matched related or matched unrelated donor is not available.

Effect of CD8⁺ cell content on umbilical cord blood transplantation in adults with hematological malignancies

Total nucleated (TNCs) and CD34(+) cells are considered major determinants of outcome after umbilical cord blood (UCB) transplantation but the effect of other cell subtypes present in the graft is unknown. This single-center cohort study included patients with hematological malignancies who received UCB transplantation after a myeloablative conditioning regimen. UCB units were primarily selected according to cell content, both TNCs and CD34(+) cells, and also according to the degree of HLA matching. Counts of several cell subtypes of the infused UCB unit, together with HLA disparities and other patient- and transplantation-related characteristics, were analyzed by multivariable methodology for their association with myeloid and platelet engraftment, graft-versus-host disease, nonrelapse mortality (NRM), disease-free survival (DFS), and overall survival (OS). Two hundred patients (median age, 32 years) were included in the study. In multivariable analyses, a greater number of CD8(+) cells was significantly associated with better results for myeloid (P = .001) and platelet (P = .008) engraftment, NRM (P = .02), DFS (P = .007), and OS (P = .01). CD34(+) cell content was predictive of myeloid engraftment (P < .001). This study suggests that the outcome after UCB transplantation in adults with hematological malignancies could be better when UCB grafts had a greater CD8(+) cell content.

Poor outcome with nonmyeloablative conditioning regimen before cord blood transplantation for patients with high-risk acute myeloid leukemia compared with matched related or unrelated donor transplantation

Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) is recommended for patients with high-risk acute myeloid leukemia (AML). In many situations, a matched related (MRD) or matched unrelated donor (MUD) is lacking, in which case unrelated cord blood units (UCB) provide an alternative. We analyzed the outcome of consecutive high-risk AML patients prepared with reduced-intensity conditioning (RIC) regimens and allografted with UCB (n = 32) and compared their outcome with high-risk AML patients who underwent transplantation with MRD/MUD (n = 49) in the same period of time. Grade III to IV acute graft-versus-host disease (GVHD) occurred slightly more frequently in the UCB group (25%) than in the MRD/MUD group (8%) (P = .069). Conversely, we found a lower incidence of extensive chronic GVHD in the UCB group (6%) than in the MRD/MUD group (20%, P = .085). Nonrelapse mortality at 4 years was 16% and 22% in the UCB and MRD/MUD groups, respectively (P = .529). The cumulative incidence of relapse at 4 years was significantly higher in the UCB group (60%) than in the MRD/MUD group (27%, P = .006). Leukemia-free survival (LFS) and overall survival (OS) at 4 years were 25% and 34%, respectively, in the UCB group and 50% and 56%, respectively, in the MRD/MUD group (LFS, P = .029; OS, P = .072). Multivariate analyses adjusted by cytogenetics and disease status at the time of Allo-HSCT revealed that use of UCB remained an independent predictive factor of shorter LFS (hazard ratio, 2.0; 95% confidence interval, 1.1 to 3.6; P = .018), and was associated with a trend for shorter OS (hazard ratio, 1.7; 95% confidence interval, .9 to 3.2; P = .093). Whereas UCB provides an alternative for patients with high-risk AML lacking an MRD/MUD, the high incidence of relapse after RIC-based UCB Allo-HSCT is a concern. Attempts to improve leukemic control with UCB Allo-HSCT are warranted, as well as the evaluation of other alternative donors in this context.

Long-term outcome and prognostic factors of unrelated cord blood transplantation in children with haematological malignancies: a retrospective study using the Spanish Working Party for BMT in Children (GETMON) database

Outcomes of unrelated cord blood transplants (UCBT) were assessed in 172 consecutive children, median age 5 years (range: 0.5-18), with haematological malignancies treated at nine Spanish hospitals between February 1996 and April 2009. Data were collected from the Spanish Working Party for Blood and Marrow Transplantation in Children (GETMON) database. ALL was diagnosed in 125 patients, AML in 43 and myelodysplastic syndrome in 4. Myeloid engraftment (ANC⩾0.5 × 10(9)/L) occurred in 87.2% at a median of 22 days and was associated with the total nucleated cell (TNC) dose infused and use of a TT-containing conditioning regimen. Cumulative incidence of relapse was 20% at 1 year post transplant and 29% at 3 years, being higher in patients with a diagnosis of ALL, very high risk disease and GVHD grades 0-1. Cumulative incidence of non-relapse mortality (NRM) was 19% at 100 days post transplant and 39% at 1 year. BU-FLU-TT-ATG-conditioned patients had lower NRM. Disease-free survival (DFS) was 40% at 2 years post transplant (for patients transplanted since 2006). On multivariate analysis, TNC dose infused, AML and BU-FLU-TT-ATG-conditioning regimen increased the probability of DFS. It is of paramount importance to select cord blood units with the highest cell dose. As the BU-FLU-TT-ATG-conditioning regimen was associated with better DFS owing to lower NRM, further prospective studies testing this regimen are warranted.

EBV-associated post-transplant lymphoproliferative disorder after umbilical cord blood transplantation in adults with hematological diseases

We analyzed the incidence, clinicopathological features, risk factors and prognosis of patients with EBV-associated post-transplant lymphoproliferative disorder (EBV-PTLD) in 288 adults undergoing umbilical cord blood transplantation (UCBT) at a single institution. Twelve patients developed proven EBV-PTLD at a median time of 73 days (range, 36-812). Three-year cumulative incidence (CI) of EBV-PTLD was 4.3% (95% CI: 1.9-6.7). All patients presented with extranodal involvement. Most frequently affected sites were the liver, spleen, central nervous system (CNS), Waldeyer's ring and BM in 7, 6, 4, 3 and 3 patients, respectively. One patient had polymorphic and 11 had monomorphic EBV-PTLD (7 diffuse large B-cell lymphomas not otherwise specified, 4 plasmablastic lymphomas). We confirmed donor origin and EBV infection in all histological samples. EBV-PTLD was the cause of death in 11 patients at a median time of 23 days (range, 1-84). The 3-year CI of EBV-PTLD was 12.9% (95% CI: 3.2-22.5) and 2.6% (95% CI: 0.5-4.7) for patients receiving reduced-intensity conditioning (RIC) and myeloablative conditioning, respectively (P<0.0001). In conclusion, adults with EBV-PTLD after UCBT showed frequent visceral and CNS involvement. The prognosis was poor despite routine viral monitoring and early intervention. An increased risk of EBV-PTLD was noted among recipients of RIC regimens.

Umbilical cord blood transplantation from unrelated donors in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia

There are very few disease-specific studies focusing on outcomes of umbilical cord blood transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia. We report the outcome of 45 patients with Philadelphia chromosome-positive acute lymphoblastic leukemia who underwent myeloablative single unit cord blood transplantation from unrelated donors within the GETH/GITMO cooperative group. Conditioning regimens were based on combinations of thiotepa, busulfan, cyclophospamide or fludarabine, and antithymocyte globulin. At the time of transplantation, 35 patients (78%) were in first complete remission, four (8%) in second complete remission and six (14%) in third or subsequent response. The cumulative incidence of myeloid engraftment was 96% at a median time of 20 days and significantly better for patients receiving higher doses of CD34(+) cells. The incidence of acute grade II-IV graft-versus-host disease was 31%, while that of overall chronic graft-versus-host disease was 53%. Treatment-related mortality was 17% at day +100 and 31% at 5 years. The 5-year relapse, event-free survival and overall survival rates were 31%, 36% and 44%, respectively. Although the event-free and overall survival rates in patients without BCR/ABL transcripts detectable at time of transplant were better than those in whom BCR/ABL transcripts were detected (46% versus 24% and 60% versus 30%, respectively) these differences were not statistically significant in the univariate analysis (P=0.07). These results demonstrate that umbilical cord blood transplantation from unrelated donors can be a curative treatment for a substantial number of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia.

Myeloablative cord blood transplantation in adults with acute leukemia: comparison of two different transplant platforms

We compared the clinical outcomes of adults with acute leukemia that received single-unit umbilical cord blood transplantation (sUCBT) after conditioning with a busulfan/antithymocyte globulin (BU-ATG)-based regimen at University Hospital La Fe (n = 102) or double-unit UCBT (dUCBT) after conditioning with a total body irradiation (TBI)-based regimen at the University of Minnesota (n = 91). Nonrelapse mortality, relapse and disease-free survival were similar in the 2 groups. Multivariate analyses, showed more rapid neutrophil (hazard ratio [HR], .6; 95% confidence interval [CI], .45 to .80; P = .0006) and platelet recovery (HR, .59; 95% CI, .43 to.83; P = .002) after the BU-ATG-based conditioning and sUCBT. Although there was a lower risk of acute graft-versus-host disease (GVHD) grade II to IV (HR, 2.81; 95% CI, 1.75 to 4.35; P < .001) after BU-ATG and sUCBT, the incidences of grade III to IV acute and chronic GVHD were similar between the 2 groups. Regarding disease-specific outcomes, disease-free survival in both acute myeloid leukemia and acute lymphoblastic leukemia (ALL) patients were not significantly different; however, a significantly lower relapse rate was found in patients with ALL treated with TBI and dUCBT (HR, .3; 95% CI, .12 to .84; P = .02). In the context of these specific treatment platforms, our study demonstrates that sUCB and dUCBT offer similar outcomes.

Impact of graft-versus-host disease prophylaxis on outcomes after myeloablative single-unit umbilical cord blood transplantation

Myeloablative single-unit umbilical cord blood transplantation (sUCBT) using busulfan, thiotepa, fludarabine, and antithymocyte globulin (Grupo Español de Trasplante Hematopoyético [GETH]-2005 protocol) resulted in high rates of engraftment and high antitumor activity. We designed a new graft-versus-host disease prophylaxis, substituting long-term steroids with mycophenolate mofetil together with a slight reduction of antithymocyte globulin (GETH/Gruppo Italiano Trapianto Midollo Osseo [GITMO]-2008 protocol). The results in 145 consecutive patients were compared with those obtained in 88 patients from the previous GETH-2005 trial. The cumulative incidence (CI) of myeloid engraftment at 60 days for patients in the GETH-2005 and GETH/GITMO-2008 trials was 94% and 88%, respectively, at a median time to neutrophil recovery of 19 and 23 days, respectively (P < .0001). In the multivariable analyses, platelet engraftment, acute and chronic graft-versus-host disease, nonrelapse mortality, relapse, and event-free survival were not significantly different. The 3-year event-free survival rate in the GETH/GITMO-2008 trial was 66%, 31%, and 25% for patients transplanted in early, intermediate, and advanced stages of the disease, respectively (P < .0001). This study confirms that myeloablative sUCBT using busulfan-based conditioning is a valuable strategy for patients with hematological malignancies. The use of mycophenolate mofetil apparently had an adverse effect on myeloid engraftment, and therefore a cautious use of this agent is warranted in the UCBT setting.

Double-unit cord blood transplantation after myeloablative conditioning for patients with hematologic malignancies: a multicenter phase II study in Japan

We analyzed the outcomes of 61 patients with hematologic malignancies who underwent double-unit cord blood transplantation (dCBT) after myeloablative conditioning performed as part of a prospective multicenter phase II study. The conditioning regimen for dCBT included total body irradiation, cyclophosphamide, and granulocyte colony-stimulating factor combined with cytosine arabinoside for myeloid malignancies and with total body irradiation and cyclophosphamide for lymphoid malignancies. The cumulative incidence of neutrophil engraftment after dCBT was 85% (95% confidence interval [CI], 73%-92%). All 51 of the patients who engrafted had complete chimerism derived from a single donor by day +60. Only the degree of HLA disparity in the host-versus-graft direction had an impact on unit dominance. The cumulative incidence of grade II-IV acute graft-versus-host disease was 25% (95% CI, 15%-37%), and that of chronic graft-versus-host disease was 32% (95% CI, 20%-44%). The 1-year cumulative incidence of relapse was 23% (95% CI, 13%-34%), and that of transplantation-related mortality was 28% (95% CI, 17%-39%). With a median follow-up of 41 months, event-free survival was 48% (90% CI, 37%-58%) at 1 year and 46% (90% CI, 35%-56%) at 3 years. Event-free survival at 3 years was 67% (95% CI, 46%-81%) for patients with standard risk and 29% (95% CI, 15%-45%) for those with advanced risk. This study suggests that dCBT after myeloablative conditioning is a promising alternative for adults and large children with hematologic malignancies who need stem cell transplantation but lack a suitable adult donor or an adequate single-unit cord blood graft.

Impact of a donor source on adult Philadelphia chromosome-negative acute lymphoblastic leukemia: a retrospective analysis from the Adult Acute Lymphoblastic Leukemia Working Group of the Japan Society for Hematopoietic Cell Transplantation

BACKGROUND

We aimed to clarify the impact of the donor source of allogeneic stem cell transplantation (allo-SCT) on Philadelphia chromosome-negative acute lymphoblastic leukemia [Ph(-) ALL] with focus on cord blood (CB).

PATIENTS AND METHODS

We retrospectively analyzed data of 1726 patients who underwent myeloablative allo-SCT for adult Ph(-) ALL. The sources of the allo-SCT were related donors (RD; N = 684), unrelated donors (URD; N = 809), and CB (N = 233).

RESULTS

Overall survival (OS) in patients after CB allo-SCT in first complete remission (CR1) was comparable with that after RD or URD allo-SCT (RD: 65%, URD: 64% and CB: 57% at 4 years, P = 0.11). CB was not a significant risk factor for relapse or non-relapse mortality as well as for OS in multivariate analyses. Similarly, the donor source was not a significant risk factor for OS in subsequent CR or non-CR (RD: 47%, URD: 39% and CB: 48% in subsequent CR, P = 0.33; RD: 15%, URD: 21% and CB: 18% in non-CR, P = 0.20 at 4 years).

CONCLUSION

Allo-SCT using CB led to OS similar to those of RD or URD in any disease status. To avoid missing the appropriate timing, CB is a favorable alternative source for adult Ph(-) ALL patients without a suitable RD or URD.

Insights and hopes in umbilical cord blood stem cell transplantations

Over 20.000 umblical cord blood transplantations (UCBT) have been carried out around the world. Indeed, UCBT represents an attractive source of donor hematopoietic stem cells (HSCs) and, offer interesting features (e.g., lower graft-versus-host disease) compared to bone marrow transplantation (BMT). Thereby, UCBT often represents the unique curative option against several blood diseases. Recent advances in the field of UCBT, consisted to develop strategies to expand umbilical stem cells and shorter the timing of their engraftment, subsequently enhancing their availability for enhanced efficacy of transplantation into indicated patients with malignant diseases (e.g., leukemia) or non-malignant diseases (e.g., thalassemia major). Several studies showed that the expansion and homing of UCBSCs depends on specific biological factors and cell types (e.g., cytokines, neuropeptides, co-culture with stromal cells). In this review, we extensively present the advantages and disadvantages of current hematopoietic stem cell transplantations (HSCTs), compared to UBCT. We further describe the importance of cord blood content and obstetric factors on cord blood selection, and report the recent approaches that can be undertook to improve cord blood stem cell expansion as well as engraftment. Eventually, we provide two majors examples underlining the importance of UCBT as a potential cure for blood diseases.