Factors Associated with Long-Term Risk of Relapse after Unrelated Cord Blood Transplantation in Children with Acute Lymphoblastic Leukemia in Remission

Comparative retrospective analysis of cord blood transplantation with ATG-containing conditioning regimens and haploidentical stem cell transplantation: similar survival outcomes with reduced incidence of GVHD

BACKGROUND

Cord blood (CB) is widely used in treating haematologic disorders due to its broad availability, tolerance to significant histocompatibility antigen disparities, and low incidence of chronic graft-versus-host disease (cGVHD). The cord blood transplantation (CBT) with anti-thymocyte globulin (ATG)-containing conditioning regimens shows promise in this regard.

METHODS

We conducted a retrospective review of data from patients who underwent CBT at our centre from August 2003 to December 2022. Patients undergoing CBT with ATG were matched with those who received HLA-haploidentical haematopoietic stem cell transplantation (haplo-HSCT). Propensity score matching (PSM) was utilized to form 105 matched pairs (140 patients) for comprehensive trial analysis.

RESULTS

The cumulative incidence of neutrophil and platelet engraftment was significantly lower in the CBT group. Patients in the CBT group exhibited significantly lower incidences of grade II-IV acute GVHD (aGVHD) and cGVHD compared to the haplo-HSCT group (8.57% vs. 29.52%, p = 0.012; 20% vs. 39.05%, p = 0.031). The overall survival (OS) rate for the CBT and haplo-HSCT groups showed no significant difference. In patients with leukaemia, the CBT cohort showed better OS, GVHD-free and relapse-free survival (GRFS), as well as a lower incidence of disease relapse, although there was no statistical difference.

CONCLUSION

Our single-centre retrospective long-term follow-up investigations indicated that although the implantation rate of CBT is lower than that of haplo-HSCT, patients undergoing CBT with ATG-containing conditioning regimens may have a comparable overall survival with a lower risk of GVHD compared to those undergoing haplo-HSCT.

Impact of center volume on outcomes in allogeneic hematopoietic cell transplantation for children

The impact of center volume on outcomes in pediatric hematopoietic cell transplantation (HCT) is not well established. We retrospectively analyzed data from a nationwide registry, including 6966 pediatric patients who underwent their first allogeneic HCT at 123 centers in Japan between 2001 and 2020. Centers were categorized by transplant volume as low volume centers (C1, the smallest number of transplantation), medium-low volume centers (C2), medium-high volume centers (C3), and high volume centers (C4, the greatest number of transplantation), and outcomes were compared across these categories. The analysis revealed no statistically significant differences in HCT outcomes among center categories. The 5-year OS by center category was 66.8% (95% CI 64.4-69.0%) for C1, 66.8% (95% CI 64.5-69.0%) for C2, 67.9% (95% CI 65.6-70.2%) for C3, and 68.3% (95% CI 65.9-70.6%) for C4. These results were consistent even when analysis was restricted to malignant and nonmalignant diseases. Our findings suggest that, unlike in adult HCT, outcomes for pediatric HCT are not significantly affected by center volume. These results indicate the consistent quality of care across centers, supporting the accessibility of HCT at various institutions for pediatric patients.

Outcomes and prognostic factors associated with relapse after haploidentical stem cell transplantation for paediatric T-cell acute lymphoblastic leukaemia

The outcomes are poor for paediatric patients with T-cell acute lymphoblastic leukaemia (T-ALL) who relapse after haematopoietic stem cell transplantation (HSCT). However, studies focusing on paediatric patients with T-ALL following haploidentical HSCT (haplo-HSCT) are limited. We retrospectively identified a consecutive cohort comprising of 128 paediatric T-ALL after haplo-HSCT from 2642 consecutive ALL patients between January 2010 and June 2022. The 2-year overall survival and leukaemia-free survival were 67.77% ± 4.21% and 66.34% ± 3.82%, respectively, and the cumulative incidence of relapse (CIR) and non-relapse mortality were 33.82% ± 0.70% and 12.65% ± 0.46% respectively. According to the multivariate Cox regression analysis, CD34 cells, minimal residual disease (MRD) ≥0.01% before HSCT, chronic graft-versus-host disease (cGvHD) and cytomegalovirus were associated with relapse (p < 0.05). To develop a scoring system for stratifying patients, we combined the variables and stratified them into low (0-2 points) and high (3, 4) groups. Consequently, the 2-year CIR in low and high groups were 23.76% ± 1.83% and 48.22% ± 2.42% (p = 0.009), respectively. Children with T-ALL have poor long-term survival, and haplo-HSCT is a potent and safe treatment; however, the incidence of relapse is high. Eliminating pre-HSCT MRD, guaranteeing sufficient CD34 cells infusion and the occurrence of cGvHD and cytomegalovirus reactivation may benefit from relapse.

New player in CAR-T manufacture field: comparison of umbilical cord to peripheral blood strategies

One of the most successful treatments in hematologic cancer is chimeric antigen receptor (CAR)-T cell-based immunotherapy. However, CAR-T therapy is not without challenges like the costly manufacturing process required to personalize each treatment for individual patients or graft-versus-host disease. Umbilical cord blood (UCB) has been most commonly used for hematopoietic cell transplant as it offers several advantages, including its rich source of hematopoietic stem cells, lower risk of graft-versus-host disease, and easier matching for recipients due to less stringent HLA requirements compared to bone marrow or peripheral blood stem cells. In this review, we have discussed the advantages and disadvantages of different CAR-T cell manufacturing strategies with the use of allogeneic and autologous peripheral blood cells. We compare them to the UCB approach and discuss ongoing pre-clinical and clinical trials in the field. Finally, we propose a cord blood bank as a readily available source of CAR-T cells.

Comparable outcomes after busulfan- or treosulfan-based conditioning for allo-HSCT in children with ALL: results of FORUM

ABSTRACT

The superiority of total body irradiation (TBI)-based vs chemotherapy conditioning for allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children with acute lymphoblastic leukemia (ALL) has been established in the international, prospective phase-3 FORUM study, randomizing 417 patients aged 4-18 years in complete remission (CR), who received allo-HSCT from HLA-matched sibling or unrelated donors. Because of the unavailability of TBI in some regions and to accommodate individual contraindications, this study reports the prespecified comparison of outcomes of patients receiving busulfan (BU)- or treosulfan (TREO)-based regimens from 2013 to 2018. Overall, 180 and 128 patients received BU/thiotepa (THIO)/fludarabine (FLU) or TREO/THIO/FLU, respectively. Data were analyzed as of February 2023, with a median follow-up of 4.2 years (range, 0.3-9.1). 3-year overall survival was 0.71 (BU, 95% confidence interval [0.64-0.77]) and 0.72 (TREO, [0.63-0.79]) and 3-year event-free survival was 0.60 (BU, [0.53-0.67]) and 0.55 (TREO, [0.46-0.63]). The 3-year cumulative incidence of relapse (BU, 0.31 [0.25-0.38]; TREO, 0.36 [0.27-0.44]); and nonrelapse mortality (BU, 0.08 [0.05-0.13]; TREO, 0.09 [0.05-0.15]) were comparable. One case of fatal veno-occlusive disease occurred in each group. No significant differences in acute and chronic graft-versus-host disease (GVHD) or 3-year GVHD-free and relapse-free survival (BU, 0.48 [0.41-0.55]; TREO, 0.45 [0.37-0.54]) were recorded. Outcomes for patients in first and second CR were similar irrespective of the regimen. In conclusion, BU/THIO/FLU or TREO/THIO/FLU regimens can be an alternative to TBI for patients with ALL aged >4 years with contraindications or lack of access to TBI. This trial was registered at www.ClinicalTrials.gov as #NCT01949129.

Comparing haploidentical transplantation with post-transplantation cyclophosphamide and umbilical cord blood transplantation using targeted busulfan in children and adolescents with hematologic malignancies

PURPOSE

This study compared the outcomes of haploidentical-related donor (HRD) and umbilical cord blood (UCB) hematopoietic stem cell transplantation (HSCT) in pediatric patients with hematologic malignancies.

METHODS

Data on patients who underwent HRD HSCT with post-transplant cyclophosphamide (n = 41) and UCB HSCT (n = 24) after targeted busulfan-based myeloablative conditioning with intensive pharmacokinetic monitoring between 2009 and 2018 were retrospectively analyzed.

RESULTS

The median follow-up durations in the HRD and UCB groups were 7.0 and 10.9 years, respectively. The cumulative incidence of acute graft-versus-host disease (GVHD) grades II-IV and moderate-to-severe chronic GVHD did not differ significantly between the groups. However, the HRD group demonstrated significantly lower rates of acute GVHD grades III-IV (4.9% vs. 29.2%, p = 0.009) and non-relapse mortality (2.6% vs. 34.2%, p < 0.001) but a higher relapse incidence (32.1% vs. 8.8%, p = 0.004) than the UCB group. The 5-year event-free and overall survival rates were 65.8% and 54.2% (p = 0.204) and 78.0% and 65.7% (p = 0.142) for the HRD and UCB groups, respectively. Multivariate analysis identified disease status as a significant risk factor for overall survival (hazard ratio, 3.24; p = 0.016). Additionally, UCB HSCT exhibited a trend toward worse event-free survival compared to HRD HSCT (hazard ratio, 2.63; p = 0.05).

CONCLUSIONS

These findings indicate that HRD HSCT with post-transplant cyclophosphamide provides promising outcomes compared to UCB HSCT in pediatric patients, with a trend toward improved survival over a long-term follow-up period exceeding a median of 7 years. Thus, HRD HSCT may be a valuable option for pediatric patients without human leukocyte antigen-matched donors.

Impact of MRD on clinical outcomes of unrelated hematopoietic stem cell transplantation in patients with Ph+ ALL: A retrospective nationwide study

Measurable residual disease (MRD) status before transplantation has been shown to be a strong prognostic factor in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). However, the outcomes of unrelated hematopoietic stem cell transplantation based on the MRD status have not been fully investigated. In this retrospective study, we compared the outcomes of 715 consecutive adults with Ph+ ALL in complete remission who underwent unrelated cord blood transplantation (UCBT) (single-unit UCBT, n = 232 [4/6, 5/6, and 6/6 HLA match]), HLA-matched unrelated bone marrow transplantation (UBMT; n = 292 [8/8 HLA match]), or HLA-mismatched UBMT (n = 191 [7/8 HLA match]). In the MRD+ cohort, adjusted 3-year leukemia-free survival rates were 59.8%, 38.3%, and 55.5% after UCBT, HLA-matched UBMT, and HLA-mismatched UBMT, respectively. In the MRD- cohort, the corresponding rates were 65.3%, 70.4%, and 69.7%, respectively. The MRD+ HLA-matched UBMT group had a significantly higher risk of relapse than the MRD+ HLA-mismatched UBMT group (hazard ratio [HR] in the MRD+ HLA-mismatched UBMT group, 0.33; 95% confidence interval [CI] 0.15-0.74) and the MRD+ UCBT group (HR in the MRD+ UCBT group, 0.38; 95% CI 0.18-0.83). Furthermore, HLA-matched UBMT had a significant effect of MRD on death (HR 1.87; 95% CI 1.19-2.94), relapse or death (HR 2.24; 95% CI 1.50-3.34), and relapse (HR 3.12; 95% CI 1.75-5.57), while UCBT and HLA-mismatched UBMT did not. In conclusion, our data indicate Ph+ ALL patients with positive MRD may benefit from undergoing UCBT or HLA-mismatched UBMT instead of HLA-matched UBMT to reduce leukemic relapse.

Total Body Irradiation Versus Chemotherapy Conditioning in Pediatric Acute Lymphoblastic Leukemia Patients Undergoing Hematopoietic Stem Cell Transplant: A Systematic Review and Meta-Analysis

Allogeneic hematopoietic stem cell transplant (HSCT) is indicated in pediatric patients with acute lymphoblastic leukemia (ALL) who have relapsed or are at a very high risk of relapse during first complete remission. Two types of myeloablative conditioning are employed before allogeneic HSCT: total body irradiation (TBI)-based regimens and chemotherapy (CHT) alone. This study compares the efficacy and safety of TBI-based regimens and CHT-based conditioning in pediatric, adolescent, and young adult patients with ALL (0-24 years old). TBI-based and CHT-conditioning regimens were evaluated in 4262 and 1367 patients, respectively, from 15 studies. Compared to CHT alone, TBI-based regimens were associated with better overall survival (OS), relative risk (RR) 1.21, better event-free survival (RR 1.34), and a reduced risk of relapse (RR 0.69). Both approaches had comparable risk of acute graft-versus-host disease (GVHD), grades 3 to 4 acute GVHD, chronic GVHD, and nonrelapse mortality (NRM). In the subgroup analysis for patients in first complete remission, TBI-based regimens and CHT alone had comparable OS and NRM. Our results demonstrate the superiority of TBI-based regimens compared to CHT alone in pediatric patients with ALL.

Controversies and expectations for the prevention of GVHD: A biological and clinical perspective

Severe acute and chronic graft versus host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. Historically, cord blood and matched sibling transplantation has been associated with the lowest rates of GVHD. Newer methods have modified the lymphocyte components to minimize alloimmunity, including: anti-thymocyte globulin, post-transplant cyclophosphamide, alpha/beta T cell depletion, and abatacept. These agents have shown promise in reducing severe GVHD, however, can be associated with increased risks of relapse, graft failure, infections, and delayed immune reconstitution. Nonetheless, these GVHD prophylaxis strategies have permitted expansion of donor sources, especially critical for those of non-Caucasian decent who previously lacked transplant options. This review will focus on the biologic mechanisms driving GVHD, the method by which each agent impacts these activated pathways, and the clinical consequences of these modern prophylaxis approaches. In addition, emerging novel targeted strategies will be described. These GVHD prophylaxis approaches have revolutionized our ability to increase access to transplant and have provided important insights into the biology of GVHD and immune reconstitution.

Impact of KIR-ligand mismatch on pediatric T-cell acute lymphoblastic leukemia in unrelated cord blood transplantation

BACKGROUND

Currently, allogeneic hematopoietic stem cell transplantation (allo-HSCT) is considered to be indicated for children and adolescents with high-risk or relapsed T-cell acute lymphoblastic leukemia (T-ALL); however, the outcomes are unsatisfactory. Killer cell immunoglobulin-like receptors (KIRs) are the main receptors on natural killer (NK) cells that play an important role in the graft-versus-leukemia effect after allo-HSCT. In allo-HSCT, when the recipient lacks a donor KIR-ligand (KIR-ligand mismatch in the graft-versus-host [GVH] direction), donor NK cells will be activated against recipient cells. KIR-ligand mismatch in the GVH direction improves outcomes after unrelated cord blood transplantation (UCBT) with acute myeloid leukemia, but the effect in T-ALL is unclear.

OBJECTIVE

We evaluated the impact of KIR-ligand mismatch in the GVH direction on the transplant outcomes of children and adolescents with T-ALL who received UCBT.

STUDY DESIGN

We conducted a retrospective study using a nationwide registry of the Japanese Society for Transplantation and Cellular Therapy. Patients diagnosed with T-ALL, aged 0-19 years, and underwent first UCBT between 1999 and 2017 were included.

RESULTS

A total of 91 patients were included in this study. In all, 23 (25.3%) percent of patients had KIR-ligand mismatch in the GVH direction. The 5-year leukemia-free survival (LFS) and overall survival (OS) rates after UCBT were 65.8% and 69.6%, respectively. In a multivariate analysis, KIR-ligand mismatch in the GVH direction was associated with a significant reduction in the relapse rate (hazard ratio [HR], 0.19; P = 0.002), resulting in better LFS (HR, 0.18; P = 0.010) and OS (HR, 0.26; P = 0.048) without increasing non-relapse mortality (NRM; HR, 1.90; P = 0.264). The cumulative incidence of GVH disease (GVHD) did not differ between patients with and without KIR-ligand mismatch (grade II-IV acute GVHD, 39.1% versus 36.8%, P = 0.648, grade III-IV acute GVHD, 13.0% versus 11.8%, P = 0.857, and chronic GVHD, 26.1% versus 22.9%, P = 0.736, respectively). Furthermore, acute and chronic GVHD were not associated with good patient outcomes. Notably, no relapse was observed in patients who received KIR-ligand mismatched UCBT in complete remission.

CONCLUSION

KIR-ligand mismatch in the GVH direction improved LFS and decreased relapse rates without increasing NRM in children and adolescents with T-ALL who received UCBT, which was not mediated by GVHD.

Title: Prognostic factors of children and adolescents with T-cell acute lymphoblastic leukemia after allogeneic transplantation

Acute lymphoblastic leukemia (ALL) is the most common cancer during childhood, and some high-risk patients with ALL require hematopoietic stem cell transplantation (HSCT). Mainly due to small patient numbers, studies focusing specifically on children and adolescents with T-cell ALL (T-ALL) are limited. Using a nationwide registry, we retrospectively analyzed data from patients under 20 years old who underwent their first HSCT for T-ALL between 2000 and 2018. As a result, total 484 patients were included, and their median follow-up period was 6.9 years after HSCT for survivors. While patients receiving HSCT at first complete remission (CR) showed relatively good 5-year leukemia free survival (5yLFS, 73.5%), once relapse occurred, their prognosis was much worse (44.4%) even if they attained second remission again (p < 0.001). Among patients receiving HSCT at CR1, grade II-IV acute graft versus host disease was associated with worse overall and LFS than grade 0-I (5yLFS 69.5% vs 82.1%, p = 0.026) mainly due to high non-relapse mortality. Among those patients, patients receiving related bone marrow transplantation, unrelated bone marrow transplantation, or unrelated cord blood transplantation showed similar survival (5yLFS, 73.2%, 76.3%, and 77.0%, respectively). For patients undergoing cord blood transplantation at CR1, total-body irradiation-based myeloablative conditioning was associated with better 5yLFS than other conditioning regimens (85.4% vs 62.2%, p = 0.044), as it reduced the risk of relapse. These results indicate that relapsed patients have much less chance of cure, and that identifying patients who require HSCT for cure and offering them HSCT with optimal settings during CR1 are crucial for children and adolescents with T-ALL. This article is protected by copyright. All rights reserved.

Total Body Irradiation in Haematopoietic Stem Cell Transplantation for Paediatric Acute Lymphoblastic Leukaemia: Review of the Literature and Future Directions

Total body irradiation (TBI) has been a pivotal component of the conditioning regimen for allogeneic myeloablative haematopoietic stem cell transplantation (HSCT) in very-high-risk acute lymphoblastic leukaemia (ALL) for decades, especially in children and young adults. The myeloablative conditioning regimen has two aims: (1) to eradicate leukaemic cells, and (2) to prevent rejection of the graft through suppression of the recipient's immune system. Radiotherapy has the advantage of achieving an adequate dose effect in sanctuary sites and in areas with poor blood supply. However, radiotherapy is subject to radiobiological trade-offs between ALL cell destruction, immune and haematopoietic stem cell survival, and various adverse effects in normal tissue. To diminish toxicity, a shift from single-fraction to fractionated TBI has taken place. However, HSCT and TBI are still associated with multiple late sequelae, leaving room for improvement. This review discusses the past developments of TBI and considerations for dose, fractionation and dose-rate, as well as issues regarding TBI setup performance, limitations and possibilities for improvement. TBI is typically delivered using conventional irradiation techniques and centres have locally developed heterogeneous treatment methods and ways to achieve reduced doses in several organs. There are, however, limitations in options to shield organs at risk without compromising the anti-leukaemic and immunosuppressive effects of conventional TBI. Technological improvements in radiotherapy planning and delivery with highly conformal TBI or total marrow irradiation (TMI), and total marrow and lymphoid irradiation (TMLI) have opened the way to investigate the potential reduction of radiotherapy-related toxicities without jeopardising efficacy. The demonstration of the superiority of TBI compared with chemotherapy-only conditioning regimens for event-free and overall survival in the randomised For Omitting Radiation Under Majority age (FORUM) trial in children with high-risk ALL makes exploration of the optimal use of TBI delivery mandatory. Standardisation and comprehensive reporting of conventional TBI techniques as well as cooperation between radiotherapy centres may help to increase the ratio between treatment outcomes and toxicity, and future studies must determine potential added benefit of innovative conformal techniques to ultimately improve quality of life for paediatric ALL patients receiving TBI-conditioned HSCT.

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.

Impact of mother donor, peripheral blood stem cells and measurable residual disease on outcomes after haploidentical hematopoietic cell transplantation with post-transplant cyclophosphamide in children with acute leukaemia

Haploidentical hematopoietic-cell transplantation using post-transplant cyclophosphamide(Haplo-PTCy) is a feasible procedure in children with haematologic malignancies. However, data of a large series of children with acute leukaemia(AL) in this setting is missing. We analysed 144 AL Haplo-PTCy paediatric recipients; median age was 10 years. Patients had acute lymphoblastic(ALL; n = 86) or myeloblastic leukaemia(AML; n = 58) and were transplanted in remission(CR1: n = 40; CR2: n = 57; CR3+: n = 27) or relapse (n = 20). Bone marrow was the graft source in 57%; donors were father (54%), mother (35%), or sibling (11%). Myeloablative conditioning was used in 87%. Median follow-up was 31 months. At day +100, cumulative incidence (CI) of neutrophil recovery and acute GVHD (II-IV) were 94% and 40%, respectively. At 2-years, CI of chronic GVHD and relapse, were 31%, 40%, and estimated 2-year overall survival (OS), leukaemia-free survival (LFS) and graft-versus-host-relapse-free survival (GRFS) were 52%, 44% and 34% respectively. For patients transplanted in remission, positive measurable residual disease (MRD) prior to transplant was associated with decreased LFS (p = 0.05) and GRFS (p = 0.003) and increased risk of relapse (p = 0.02). Mother donor was associated with increased risk of chronic GVHD (p = 0.001), decreased OS (p = 0.03) and GRFS (p = 0.004). Use of PBSC was associated with increased risk of chronic GVHD (p = 0.04). In conclusion, achieving MRD negativity pre-transplant, avoiding use of mother donors and PBSC as graft source may improve outcomes of Haplo-PTCy in children with AL.

Predictors of hematologic malignancy relapse in patients with advanced chronic graft-versus-host disease

Malignancy relapse remains a major barrier to treatment success in patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Chronic graft-versus-host disease (cGVHD) markedly reduces hematologic malignancy relapse risk, but relapses still occur in these patients. Patients (n = 275) with moderate or severe cGVHD were enrolled on the National Cancer Institute (NCI) prospective cross-sectional natural history study (NCT00092235). Subjects were median 36 months after allo-HSCT and were followed subsequently for malignancy relapse and survival. Seventeen patients experienced relapse. In a multivariable model including time-dependent influences on relapse, risk factors associated with increased risk of relapse included shorter time from transplant to cGVHD evaluation (HR 0.279, 95% CI 0.078-0.995) and lower number of prior lines of systemic immunosuppressive therapy for cGVHD (HR 0.260, 95% CI 0.094-0.719). In a model excluding time-dependent influences on relapse risk, lower number of prior lines of systemic immunosuppressive therapy for cGVHD (HR 0.288, 95% CI 0.103-0.804), lower C4 complement level (HR 0.346, 95% CI 0.129-0.923), and higher body mass index (HR 3.222, 95% CI 1.156-8.974), were all associated with increased relapse risk. Parameters indicating cGVHD severity and activity are associated with risk of malignancy relapse. Classical predictors of relapse after allo-HSCT do not seem to be prognostic.

Relapse, Mortality, and the Associated Factors in Children with Acute Lymphoblastic Leukemia; A Competing Risks Analysis

Background: Acute lymphoblastic leukemia (ALL) is the most frequent form of malignant neoplasia diagnosed in ages 0 to 14 years old. Efforts have not yet converted into a better prospect. Bone marrow relapse is still the leading cause of person-year of life lost in this malignancy. Objectives: This study aimed at identifying the associated risk factors for relapse and mortality for pediatric patients with ALL in standard and high-risk groups. Methods: This study included a cohort of pediatric (0 - 16 years old) patients with ALL referred to Sheikh Hospital, Mashhad, Iran from 2007 to 2016. The demographic, clinical, and laboratory information were considered. Hazard ration (HR) with 95% highest posterior density region was obtained, using a Bayesian competing risks model. Results: Of 424 patients with a mean age of 5.56 ± 3.75 years, 172 (40%) were female. Median follow-up time was 43.29 months, 10.6% had a relapse, and 17.2% had mortality related to ALL. Relapse-free survival rates at 1, 3, and 5 years were 97, 91, and 88%, respectively. Overall survival rates were 86, 83, and 82%, respectively. In the standard-risk group, tumor lysis syndrome (TLS) significantly increased either the relapse risk [HR: 13.47 (2.05 - 67.54)] or mortality risk [HR: 19.57 (2.24 - 32.18)]. In the high-risk group, the higher level of hemoglobin, platelet, and lactic acid dehydrogenase was significantly associated with higher relapse risk. TLS was associated with a higher risk of mortality in high-risk groups. Conclusions: It was suggested that TLS was a predictor for the disease relapse as well as mortality in pediatric patients with ALL. However, further evaluation on the larger population of patients is demanded to ascertain the precision of such parameters in leukemic management strategies.

Intrabone infusion for allogeneic umbilical cord blood transplantation in children

Umbilical cord blood transplantation (UCBT) has been used to treat malignant and non-malignant diseases. UCBT offers the advantages of easy procurement and acceptable partial HLA mismatches, but also shows delayed hematopoietic and immunological recoveries. We postulated that an intrabone (IB) infusion of cord blood could provide a faster short- and long-term engraftment in a pediatric population with malignant and non-malignant hematologic diseases. We conducted this phase I-II single arm, exploratory clinical trial (NCT01711788) from 2012 to 2016 in a single center. Fifteen patients aged from 1.9 to 16.4 years received an IB UCBT. Median time to neutrophils and platelet recoveries were 18 days (range: 13-36 days) and 42 days (range: 26-107 days), respectively. Rate of severe acute GVH grade was low, with only one patient with grade III aGVH. Relapse occurred in 5 patients (38.5%) and TRM occurred in 1 patient. This leads to 6 years EFS and OS of 66.7% and 80% respectively. In conclusion, IB UCBT is safe and well-tolerated in children and hematological recovery compared similarly to the results obtained with IV UCBT.

Prednisolone poor response is not an indication for HSCT in pediatric B-cell precursor acute lymphoblastic leukemia in first remission: results from JACLS ALL-02 study

Approximately 90% of pediatric acute lymphoblastic leukemia (ALL) cases are curable with intensified chemotherapy, but very high-risk patients may require hematopoietic stem cell transplantation (HSCT). A suitable indication for HSCT in the first complete remission (CR1) should be defined to protect patients from long-term complications. We report the outcomes of HSCT in CR1 from the Japan Association of Childhood Leukemia Study (JACLS) ALL-02 study and reassess indications for HSCT. Of 1114 patients, 71 (6.4%) received HSCT in CR1. Indications included high-risk cytogenetic abnormalities and non-CR on day 33. Patients with B-cell precursor (BCP) ALL and a prednisolone poor response (PPR) received HSCT when leukocyte antigen-matched siblings were available. The 4-year overall survival (OS) of transplanted patients was 78.8% (confidence interval 67.3-86.6). Multivariate analysis revealed that cord blood transplantation was associated with poor OS. For BCP-ALL patients with PPR who achieved CR1 after induction therapy, HSCT in CR1 showed excellent outcomes (4-year OS 90.9%) but demonstrated no survival advantage as the outcome with chemotherapy was also excellent (4-year OS 97.0%). This study suggests that in BCP-ALL patients PPR is not an indication for HSCT in CR1. Precise evaluation of treatment responses would increase sophistication of indications for HSCT in CR1.

Total Body Irradiation or Chemotherapy Conditioning in Childhood ALL: A Multinational, Randomized, Noninferiority Phase III Study

Total body irradiation (TBI) before allogeneic hematopoietic stem cell transplantation (HSCT) in pediatric patients with acute lymphoblastic leukemia (ALL) is efficacious, but long-term side effects are concerning. We investigated whether preparative combination chemotherapy could replace TBI in such patients.

Hematopoietic cell transplantation in pediatric patients with acute leukemias or myelodysplastic syndrome using unrelated adult or umbilical cord blood donors in Brazil

The choice of alternative donors for HCT for patients without an HLA-matched related donor depends on several factors. We compared major HCT outcomes in 212 consecutive children transplanted at 11 centers in Brazil for acute leukemia or MDS from an HLA-matched unrelated donor (MUD, n = 95), mismatched unrelated donor (MMUD, n = 47) or unrelated umbilical cord blood (UCB, n = 70). Most had ALL (61%), bone marrow (57%) as the graft source and 95% received a MAC regimen. The 3-year OS probability were 57, 55, and 37% after HCT from MUD, MMUD, and UCB, respectively (HR 1.68, 95%CI 1.07-2.63; P = .02). In comparison with MUD, OS was similar after transplantation of a ≥ 6/8 HLA-matched or a high cell dose (>5 × 10⁷ TNC/kg) CB unit (HR 1.41, 95%CI 0.88-2.27; P = .15). NRM was higher for UCB (HR 3.90, 95%CI 1.43-10.7; P = .01) but not for MMUD (HR 1.03, 95%CI 0.53-2.00; P > .20). Advanced disease (HR 2.05, 95%CI 1.26-3.33; P < .001) and UCB with high probability of being < 6/8 HLA-matched (HR 5.34, 95%CI 2.0-13.9; P < .001) were associated with higher mortality. Relapse and acute GVHD were similar among groups, while PGF was higher among UCB transplants (P = .002) and chronic GVHD among MMUD group (HR 2.88, 95% CI 1.05-7.88; P = .04). Our results suggest that in Brazil HCT outcomes performed with MMUD and MUD donors were comparable, while with UCB units < 6/8 HLA-matched were associated with higher NRM for children with acute leukemia or MDS.

Unrelated cord blood transplantation with myeloablative conditioning for pediatric acute lymphoblastic leukemia in remission: prognostic factors

The number of individuals undergoing unrelated cord blood transplantation (UCBT) has increased in recent years; however, information on prognostic factors is limited. We retrospectively analyzed data from 475 children and adolescents receiving UCBT with myeloablative conditioning for acute lymphoblastic leukemia (ALL) in complete remission (CR), based on a nationwide registry. In the total patient cohort, 5-year leukemia-free survival (LFS) and overall survival (OS) rates after UCBT were 61.1% and 67.7%, respectively. UCBT at first CR and UCBT after 2007 were associated with good survival, while grade II-IV acute graft-versus-host disease (GVHD) was associated with low relapse rate but did not affect survival. Analysis according to human leukocyte antigen (HLA) disparity revealed that tacrolimus-based GVHD prophylaxis resulted in higher OS and lower relapse rate and nonrelapse mortality (NRM) than cyclosporine-based GVHD prophylaxis in patients transplanted with 6/6 and ≤4/6 HLA-matched umbilical cord blood. Furthermore, grade II-IV acute GVHD was associated with good LFS and low relapse rate, without high NRM, in patients receiving 5/6 HLA-matched UCBT. These data indicate that prognostic factors for ALL differ depending on HLA disparity in UCBT.

Addition of Thiotepa to Total Body Irradiation and Cyclophosphamide Conditioning for Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Acute Lymphoblastic Leukemia

Total body irradiation (TBI)/cyclophosphamide (CY) is a standard-of-care conditioning regimen in allogeneic hematopoietic stem cell transplant (HSCT) for pediatric acute lymphoblastic leukemia (ALL). This study sought to identify whether the addition of thiotepa (TT) to TBI/CY improves HSCT outcomes for pediatric patients with ALL. A retrospective analysis was performed on 347 pediatric ALL patients who underwent HSCT between 1995 and 2015, with 242 receiving TBI/CY/TT and 105 patients receiving TBI/CY. There were no statistical differences in age, donor source, or complete remission status between the 2 groups. Comparison of the TBI/CY/TT versus TBI/CY groups demonstrated no difference in transplant-related mortality at 1 (11% versus 11%), 5 (13% versus 16%), or 10 years (16% versus 16%). There was lower relapse in the TBI/CY/TT group at 1 (14% versus 26%), 5 (24% versus 36%), 10 (26% versus 37%), and 15 years (26% versus 37%) (P= .02) but was not statistically significant on multivariate analysis. The TBI/CY/TT group showed a trend toward improved disease-free survival (DFS) at 5 (59% versus 47%), 10 (56% versus 46%), and 15 years (49% versus 40%) (P = .05) but was not statistically significant on multivariate analysis. Comparing overall survival at 5 (62% versus 53%), 10 (57% versus 50%), and 15 years (50% versus 44%) demonstrated no statistical difference between the 2 groups. The addition of thiotepa to TBI/CY demonstrated no increase in transplant-related mortality for pediatric ALL HSCT but was unable to demonstrate significant benefit in disease control. Minimal residual disease status remained the key risk factor impacting both relapse and DFS. More studies are warranted to better clarify the benefits of using thiotepa in conditioning for ALL HSCT.

Risk Factors for Relapse of Childhood B Cell Acute Lymphoblastic Leukemia

Background

B cell acute lymphoblastic leukemia (B-ALL) is the most common type of ALL. This study aimed to explore risk factors for relapse of childhood B-ALL.

Material/Methods

Total of 102 pediatric B-ALL patients were included in this study. B-ALL patients were divided into a relapse group and a non-relapse group. Chemotherapy-induced agranulocytosis time, fusion gene, and minimal residual disease (MRD) were assessed. White blood cell (WBC) count in peripheral blood and risk stratification were evaluated in newly-diagnosed patients. Kaplan-Meier plots were used to evaluate the correlation between risk factors and relapse rates. Multivariate analysis was performed with Cox proportional hazard model to estimate relative risk (RR), 95% confidence interval (95% CI), and hazard ratio (HR). Finally, 99 cases of B-ALL were included in this study.

Results

There were significant differences between the relapse group and the non-relapse group in age (p=0.004), chemotherapy-induced agranulocytopenia (p=0.001), WBC count in peripheral blood of newly diagnosed patients (p=0.016), risk stratification (p=0.000), and MRD at 12^th week (p=0.007). Age over 10 years, high-risk stratification, long period of agranulocytopenia, higher WBC counts, and MRD more than 10⁻⁴ were correlated with higher B-ALL relapse rate (p<0.05). Multivariate analysis showed significantly higher relapse rates for age ≥10 years, high-risk stratification, and MRD at 12^th week >10⁻⁴, with RR (95% CI) of 4.001 (1.005–15.930), 4.964 (1.050–23.456), and 4.646 (1.383–15.614), respectively.

Conclusions

Agranulocytopenia ≤7 days, peripheral blood WBC >100×10⁹/L, and MRD at 33^rd day >10⁻⁴ were associated with B-ALL relapse. Age ≥10 years, high-risk stratification, and MRD at 12^th week >10⁻⁴ were independent risk factors for relapse.

Immune reconstitution following umbilical cord blood transplantation: IRES, a study of UK paediatric patients

To obtain a qualitative as well as quantitative view immune reconstitution following umbilical cord blood (UCB) transplantation of paediatric patients, we utilised a broad panel of flow cytometry markers to monitor the phenotypes of lymphoid and myeloid cells at 1-12 months post-transplant. Samples were received from 46 patients with a median age of 3.3 years and survival was 76% at 1 year. Monocytes were at similar or higher median levels than in adult controls at all times tested, with a high CD16+ proportion in the first 3 months. NK cells were also within adult ranges, with a CD56++ high proportion in the first 6 months. B cell recovery was seen from 2 months in most patients and T cells from 3 months, both were delayed with anti-thymocyte globulin (ATG) treatment. CD4:CD8 ratios were high in the first 6 months, and the proportion of T cells with recent thymic emigrant and naïve phenotypes rose from 3 months. NK and plasmacytoid dendritic cell numbers remained at reduced levels in patients not surviving to 1 year. Our results can serve as a useful reference for detailed monitoring of immune reconstitution in paediatric recipients of UCB.

Role of antithymocyte globulin in patients with hematologic diseases undergoing umbilical cord blood transplantation: A systematic review and meta-analysis

The role of antithymocyte globulin (ATG) in patients with hematologic diseases undergoing umbilical cord blood transplantation (UCBT) remains controversial. This systematic review and meta-analysis was conducted to comprehensively evaluate this issue. PubMed, Embase, and the Cochrane Library were systematically searched. Clinical studies reporting the impact of ATG- vs non-ATG-containing conditioning regimens on transplantation outcomes were identified. Twenty-five studies were included. ATG significantly prevented grade II-IV and grade III-IV acute graft-vs-host disease (GVHD) (11 studies, 5020 patients, HR: 0.49, 95% CI: 0.42-0.56, P < .001; 5 studies, 5490 patients, HR: 0.60, 95% CI: 0.46-0.80, P < .001) but not chronic GVHD (8 studies, 5952 patients, HR: 0.78, 95% CI: 0.51-1.20, P = .266). However, use of ATG was associated with increased transplantation-related mortality and inferior overall survival (9 studies, 4244 patients, HR: 1.79, 95% CI: 1.38-2.33, P < .001; 8 studies, 5438 patients, HR: 1.96, 95% CI: 1.56-2.46, P < .001). Our study did not recommend routine use of ATG in UCBT. Individualizing the ATG timing and dose based on patient characteristics to retain the prophylactic effects of ATG on GVHD without compromising the survival of UCBT recipients may be reasonable.

Analysis of 5-hydroxytryptamine and its related indoles in cerebrospinal fluid of leukemic children by gas chromatography-mass spectrometry

Background

It is meaningful to quantify some neurotransmitters in cerebrospinal fluid (CSF) for pathology and clinical diagnosis. The objective of this study was to develop a rapid and reliable method for detecting 5-hydroxyindole ethanol (5-HTOL), 5-hydroxyindole acetic acid (5-HIAA), 5-hydroxytryptophan (5-HTP) and 5-hydroxytryptamine (5-HT) in CSF by gas chromatography-mass spectrometry (GC-MS), and explore the clinical significance of the levels of these neurotransmitters in CSF from acute lymphoblastic leukemia (ALL).

Methods

The levels of 5-HTOL, 5-HIAA, 5-HTP and 5-HT in CSF from children with ALL and a control (CON) group were examined by the proposed GC-MS method.

Results

The GC-MS method showed good sensitivity and accuracy. 5-HT and 5-HIAA contents in the ALL group were significantly lower than those in the CON group (p < 0.01), while there was no significant difference in 5-HTP and 5-HTOL contents between the two groups (p > 0.05).

Conclusions

This sensitive and reliable method could be used in studies focusing on clinical pathogenesis of ALL.

Current status of umbilical cord blood transplantation in children

The first umbilical cord blood (UCB) transplantation was performed 30 years ago. UCB transplantation (UCBT) is now widely used in children with malignant and non-malignant disorders who lack a matched family donor. UCBT affords a lower incidence of graft-versus-host disease compared to alternative stem cell sources, but also presents a slower immune recovery and a high risk of infections if serotherapy is not omitted or targeted within the conditioning regimen. The selection of UCB units with high cell content and good human leucocyte antigen match is essential to improve the outcome. Techniques, such as double UCBT, ex vivo stem cell expansion and intra-bone injection of UCB, have improved cord blood engraftment, but clinical benefit remains to be demonstrated. Cell therapies derived from UCB are under evaluation as potential novel strategies to reduce relapse and viral infections following transplantation. In recent years, improvements within haploidentical transplantation have reduced the overall use of UCBT as an alternative stem cell source; however, each may have its relative merits and disadvantages and tailored use of these alternative stem cell sources may be the optimal approach.

Allogeneic stem cell transplantation in the era of novel therapies for acute lymphoblastic leukaemia

Immunotherapy is changing the treatment of acute lymphoblastic leukaemia (ALL) in adults and children. However, regardless of these new therapies, allogeneic hematopoietic cell transplantation (allo-HCT) still play a key role in the treatment of ALL, although it is uncertain how these new therapies will impact on the transplant procedure and indications. This article reviews the indications of allo-HCT for children and adults diagnosed with ALL, the different sources and conditioning regimens for transplantation as well as the role of measurable residual diseases pre- and post-HCT in the era of the new therapies for ALL.