The impact of donor type on the outcome of pediatric patients with very high risk acute lymphoblastic leukemia. A study of the ALL SCT 2003 BFM-SG and 2007-BFM-International SG

Clinical outcomes and relapse patterns in pediatric acute leukemia patients undergoing hematopoietic cell transplantation: a multicenter Brazilian experience

Background

Hematopoietic cell transplantation (HCT) represents a well-established therapeutic strategy for high-risk leukemia, though post-transplant relapse remains a significant challenge, particularly in resource-limited settings.

Procedure

In this retrospective study, we analyzed medical records of 310 pediatric patients (age < 18 years) who underwent HCT for acute leukemias at four Brazilian institutions between 2010 and 2019.

Results

The cohort included patients with acute lymphoblastic leukemia (ALL; 74.2%) and acute myeloid leukemia (AML; 25.8%). The median age was 9.52 years (range: 0.25-17.97), with male predominance (68.3%). Total body irradiation (TBI)-based conditioning was utilized in 72.6% of cases, and bone marrow served as the predominant graft source (74.5%). Prior to transplantation, 46.5% of patients were in first complete remission. Post-transplant relapse occurred in 36.7% of patients at a median of 245 days (range: 38-2,505). With a median follow-up of 2,019 days (5.5 years), overall survival was 69.3% at one year, declining to 62.4% at two years. The cumulative incidence of relapse was 12.6%, 28.8%, and 33.4% at 100 days, one year, and two years post-HCT, respectively. Adjusted analysis revealed increased relapse risk in patients with mixed donor chimerism, positive minimal residual disease (MRD) status before HCT, and disease status beyond first complete remission (including CR2, advanced disease, and refractory disease).

Conclusions

These findings underscore the elevated relapse risk associated with advanced disease status, positive pre-HCT MRD, and mixed donor chimerism post-transplant. Future interventions should prioritize improving diagnostic capabilities, expanding access to modern treatment protocols, and facilitating early referral to transplant centers, particularly for aggressive disease presentations.

Low rate of nonrelapse mortality in under-4-year-olds with ALL given chemotherapeutic conditioning for HSCT: a phase 3 FORUM study

ABSTRACT

Allogeneic hematopoietic stem cell transplantation (HSCT) is highly effective for treating pediatric high-risk or relapsed acute lymphoblastic leukemia (ALL). For young children, total body irradiation (TBI) is associated with severe late sequelae. In the FORUM study (NCT01949129), we assessed safety, event-free survival (EFS), and overall survival (OS) of 2 TBI-free conditioning regimens in children aged <4 years with ALL. Patients received fludarabine (Flu), thiotepa (Thio), and either busulfan (Bu) or treosulfan (Treo) before HSCT. From 2013 to 2021, 191 children received transplantation and were observed for ≥6 months (median follow-up: 3 years). The 3-year OS was 0.63 (95% confidence interval [95% CI], 0.52-0.72) and 0.76 (95% CI, 0.64-0.84) for Flu/Thio/Bu and Flu/Thio/Treo (P = .075), respectively. Three-year EFS was 0.52 (95% CI, 0.41-0.61) and 0.51 (95% CI, 0.39-0.62), respectively (P = .794). Cumulative incidence of nonrelapse mortality (NRM) and relapse at 3 years were 0.06 (95% CI, 0.02-0.12) vs 0.03 (95% CI: <0.01-0.09) (P = .406) and 0.42 (95% CI, 0.31-0.52) vs 0.45 (95% CI, 0.34-0.56) (P = .920), respectively. Grade >1 acute graft-versus-host disease (GVHD) occurred in 29% of patients receiving Flu/Thio/Bu and 17% of those receiving Flu/Thio/Treo (P = .049), whereas grade 3/4 occurred in 10% and 9%, respectively (P = .813). The 3-year incidence of chronic GVHD was 0.07 (95% CI, 0.03-0.13) vs 0.05 (95% CI, 0.02-0.11), respectively (P = .518). In conclusion, both chemotherapeutic conditioning regimens were well tolerated and NRM was low. However, relapse was the major cause of treatment failure. This trial was registered at www.clinicaltrials.gov as #NCT01949129.

Parenteral Nutrition in the Pediatric Oncologic Population: Are There Any Sex Differences?

Gender-based medicine is attracting increasing interest every day, but studies on pediatric populations are still limited. In this setting, sex differences among patients undergoing total parenteral nutrition (TPN) have not been previously reported. This study investigated the presence of sex differences in parenteral nutrition composition and outcomes among a cohort of pediatric patients admitted at the Oncohematology and Bone Marrow Transplant Unit of the Institute for Maternal and Child Health "Burlo Garofolo" of Trieste, Italy. For all 145 recruited patients (87 males, 58 females), the following data were collected: age, sex, volume and duration of TPN, macro- and micronutrient composition of TPN bags, electrolytic or blood gases imbalance, glycolipid alterations, liver damage during TPN, and the incidence of sepsis and thrombosis. The analysis showed that females required higher daily phosphate intake (p = 0.054) and essential amino acid supplementation (p = 0.07), while males had a higher incidence of hypertriglyceridemia (p < 0.05) and cholestasis. A higher incidence of sepsis was found in the non-transplanted male population (p < 0.05). No significant differences were appreciable in other analyzed variables. This study aims to create a basis for future gender-based nutritional recommendations in the pediatric field.

Haploidentical vs. HLA-matched donor hematopoietic stem-cell transplantation for pediatric patients with acute lymphoblastic leukemia in second remission: A collaborative retrospective study of the Spanish Group for Bone Marrow Transplantation in Children (GETMON/GETH) and the Spanish Childhood Relapsed ALL Board (ReALLNet)

Introduction

Studies addressing the role of haploidentical as alternative to HLA-matched donors for stem cell transplantation (SCT) often include patients with diverse hematological malignancies in different remission statuses.

Methods

We compared outcomes of children with acute lymphoblastic leukemia (ALL) undergoing SCT in second complete remission (CR2) from haploidentical (n = 25) versus HLA-matched donor (n = 51).

Results

Patients were equally distributed across both groups according to age, immunophenotype, time to and site of relapse, relapse risk-group allocation, and minimal residual disease (MRD) before SCT. Incidence of graft failure, acute graft versus host disease (GVHD), and other early complications did not differ between both groups. We found no differences in overall survival (58.7% versus 59.5%; p = .8), leukemia free survival (LFS) (48% versus 36.4%; p = .5), event free survival (40% versus 34.4%; p = .69), cumulative incidence (CI) of subsequent relapse (28% versus 40.9%; p = .69), treatment related mortality (24% versus 23.6%; p = .83), CI of cGVHD (4.5% versus 18.7%; p = .2), and chronic GVHD-free and leukemia-free survival (44% versus 26.3%; p = .3) after haploidentical donor SCT. Chronic GVHD (HR = 0.09; p=.02) had protective impact, and MRD ≥ 0.01% before SCT (HR = 2.59; p=.01) had unfavorable impact on LFS.

Discussion

These results support the role of haploidentical donor SCT in children with ALL in CR2.

Cost-Effectiveness and Budget Impact Analyses of Tisagenlecleucel in Pediatric and Young Adult Patients with Relapsed or Refractory B-Cell Acute Lymphoblastic Leukemia from the Singapore Healthcare System Perspective

Purpose

Children and young adults with relapsed or refractory (r/r) acute lymphoblastic leukemia (ALL) have poor survival due to ineffective therapy options. The newly approved chimeric antigen receptor T-cell (CAR-T) therapy, tisagenlecleucel, has demonstrated improved survival but at a high up-front cost. The study aims to evaluate the cost-effectiveness and budget impact of tisagenlecleucel versus salvage chemotherapy regimen (SCR) or blinatumomab (BLN) for the treatment of pediatric and young adult patients with relapsed/refractory B-cell ALL from the Singapore healthcare system perspective.

Patients and Methods

A three-health state partitioned survival model was constructed to analyze the cost-effectiveness of tisagenlecleucel vs SCR/BLN with/without allogenic hematopoietic stem cell transplantation (allo-HSCT) over a lifetime period. Clinical efficacy for tisagenlecleucel, SCR and BLN were based on pooled data from ELIANA, ENSIGN and B2101J trials, the study by von Stackelberg et al 2011, and MT103-205 respectively. Medical costs from pre-treatment until terminal care, including treatment, side effects, follow-up, subsequent allo-HSCT and relapse, were considered. Incremental cost-effectiveness ratios (ICERs) were estimated as the incremental costs per quality-adjusted life-year (QALY) gain. Additionally, the financial impact of tisagenlecleucel introduction in Singapore was estimated, comparing the present treatment scenario (without tisagenlecleucel) with a future scenario (with tisagenlecleucel), over 5 years.

Results

In the base-case analysis, tisagenlecleucel treatment demonstrated cost-effectiveness with an ICER of S$45,840 (US$34,762) per QALY (vs SCR) and S$51,978 (US$39,315) per QALY (vs BLN). The estimated budget ranges from S$477,857 (US$361,438) to S$1.4 million (US$1.05 million) annually for the initial 5 years.

Conclusion

Tisagenlecleucel is likely to be a cost-effective treatment option with limited budget implications while treating r/r ALL patients who have failed at least 2 lines of prior therapies.

What Is the Role of HSCT in Philadelphia-Chromosome-Positive and Philadelphia-Chromosome-Like ALL in the Tyrosine Kinase Inhibitor Era?

Previously, the outcome of paediatric Philadelphia-chromosome-positive (Ph+) ALL treated with conventional chemotherapy alone was poor, necessitating the use of haematopoietic stem cell transplantation (HSCT) for the best outcomes. The recent addition of tyrosine kinase inhibitors (TKIs) alongside the chemotherapy regimens for Ph+ ALL has markedly improved outcomes, replacing the need for HSCT for lower risk patients. An additional poor prognosis group of Philadelphia-chromosome-like (Ph-like) ALL has also been identified. This group also can be targeted by TKIs in combination with chemotherapy, but the role of HSCT in this population is not clear. The impact of novel targeted immunotherapies (chimeric antigen receptor T cells and bispecific or drug-conjugated antibodies) has improved the outcome of patients, in combination with chemotherapy, and made the role of HSCT as the optimal curative therapy for Ph+ ALL and Ph-like ALL less clear. The prognosis of patients with Ph+ ALL and persistent minimal residual disease (MRD) at the end of consolidation despite TKI therapy or with additional genetic risk factors remains inferior when HSCT is not used. For such high-risk patients, HSCT using total-body-irradiation-containing conditioning is currently recommended. This review aims to provide an update on the current and future role of HSCT for Ph+ ALL and addresses key questions related to the management of these patients, including the role of HSCT in first complete remission, MRD evaluation and related actions post HSCT, TKI usage post HSCT, and the putative role of HSCT in Ph-like ALL.

Chimeric Antigen Receptor T-Cell Therapy in Paediatric B-Cell Precursor Acute Lymphoblastic Leukaemia: Curative Treatment Option or Bridge to Transplant?

Chimeric antigen receptor T-cell therapy (CAR-T) targeting CD19 has been associated with remarkable responses in paediatric patients and adolescents and young adults (AYA) with relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukaemia (BCP-ALL). Tisagenlecleucel, the first approved CD19 CAR-T, has become a viable treatment option for paediatric patients and AYAs with BCP-ALL relapsing repeatedly or after haematopoietic stem cell transplantation (HSCT). Based on the chimeric antigen receptor molecular design and the presence of a 4-1BB costimulatory domain, tisagenlecleucel can persist for a long time and thereby provide sustained leukaemia control. "Real-world" experience with tisagenlecleucel confirms the safety and efficacy profile observed in the pivotal registration trial. Recent guidelines for the recognition, management and prevention of the two most common adverse events related to CAR-T - cytokine release syndrome and immune-cell-associated neurotoxicity syndrome - have helped to further decrease treatment toxicity. Consequently, the questions of how and for whom CD19 CAR-T could substitute HSCT in BCP-ALL are inevitable. Currently, 40-50% of R/R BCP-ALL patients relapse post CD19 CAR-T with either CD19- or CD19+ disease, and consolidative HSCT has been proposed to avoid disease recurrence. Contrarily, CD19 CAR-T is currently being investigated in the upfront treatment of high-risk BCP-ALL with an aim to avoid allogeneic HSCT and associated treatment-related morbidity, mortality and late effects. To improve survival and decrease long-term side effects in children with BCP-ALL, it is important to define parameters predicting the success or failure of CAR-T, allowing the careful selection of candidates in need of HSCT consolidation. In this review, we describe the current clinical evidence on CAR-T in BCP-ALL and discuss factors associated with response to or failure of this therapy: product specifications, patient- and disease-related factors and the impact of additional therapies given before (e.g., blinatumomab and inotuzumab ozogamicin) or after infusion (e.g., CAR-T re-infusion and/or checkpoint inhibition). We discuss where to position CAR-T in the treatment of BCP-ALL and present considerations for the design of supportive trials for the different phases of disease. Finally, we elaborate on clinical settings in which CAR-T might indeed replace HSCT.

Acute Lymphoblastic Leukaemia in the Youngest: Haematopoietic Stem Cell Transplantation and Beyond

The ALL SCTped 2012 FORUM (For Omitting Radiation Under Majority age) trial compared outcomes for children ≥4 years of age transplanted for acute lymphoblastic leukaemia (ALL) who were randomised to myeloablation with a total body irradiation (TBI)-based or chemotherapy-based conditioning regimen. The TBI-based preparation was associated with a lower rate of relapse compared with chemoconditioning. Nevertheless, the age considered suitable for TBI was progressively raised over time to spare the most fragile youngest patients from irradiation-related complications. The best approach to use for children <4 years of age remains unclear. Children diagnosed with ALL in their first year of life, defined as infants, have a remarkably poorer prognosis compared with older children. This is largely explained by the biology of their ALL, with infants often carrying a KMT2A gene rearrangement, as well as by their fragility. In contrast, the clinical presentations and biological features of ALL in children >1 year but <4 years often resemble those presented by older children. In this review, we explore the state of the art regarding haematopoietic stem cell transplantation (HSCT) in children <4 years, the preparative regimens available, and new developments in the field that may influence treatment decisions.

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

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