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Unrelated cord blood transplantation in children, adolescents, and young adults with acute leukemia or myelodysplastic syndrome: a retrospective comparative study from the French Society for Bone Marrow Transplantation and Cellular Therapy (SFGM-TC) between Real-World Data and previously reported results of a Randomized Clinical Trial
Teyssier, A. C., Michel, G., Jubert, C., Rialland, F., Visentin, S., Ouachée, M., Bilger, K., Gandemer, V., Beguin, Y., Marie-Cardine, A., et al
Transplantation and cellular therapy. 2022
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Editor's Choice
Abstract
BACKGROUND We previously reported results of a French randomized clinical trial (RCT) comparing the risk of transplantation failure (including transplant-related mortality (TRM), engraftment failure, and autologous recovery) in single and double unrelated cord blood (UCB) transplantation in children and young adults with hematologic malignancies. We concluded that single-UCB transplantation with an adequate cell dose is the standard of care, leading to a 70% two-year overall survival (OS). It remains unclear, however, whether RCT participants have better outcomes than comparable patients not treated in the setting of a clinical trial. We previously reported results of a French randomized clinical trial (RCT) comparing the risk of transplantation failure (including transplant-related mortality (TRM), engraftment failure, and autologous recovery) in single and double unrelated cord blood (UCB) transplantation in children and young adults with hematologic malignancies. We concluded that single-UCB transplantation with an adequate cell dose is the standard of care, leading to a 70% two-year overall survival (OS). It remains unclear, however, whether RCT participants have better outcomes than comparable patients not treated in the setting of a clinical trial. We compared the characteristics and outcomes of RCT participants (n = 137) to a Francophone population-based registry of patients (real-world (RW) group) fulfilling the eligibility criteria used in our RCT and transplanted with one or two UCB units after a myeloablative conditioning (MAC) regimen between March 2015 (end of inclusion in the RCT) and February 2019 (n = 141). The primary endpoint was the two-year cumulative incidence (CI) of transplantation strategy failure as defined in our RCT. The two groups were comparable in terms of age, disease distribution, hematologic status at transplantation, follow-up, and HLA compatibility. Patients in the RW group were more likely to be transplanted with a single-unit UCB (87.9% versus 49.6%, p < 0.001) and to receive a radiation-free regimen (39.0% vs. 60.6%, p < 0.001). The two-year CI of transplantation strategy failure, TRM, and the two-year probability of OS were similar between the two groups, although the relapse risk was higher in the RW group (31.2% ± 7.7% vs. 20.4% ± 6.8%, p = 0.01), resulting in a significantly lower DFS (59.2% ± 8.4% vs. 69.3% ± 8.0%, p = 0.047). This difference remained statistically significant only in the group of patients with acute lymphoid leukemia (ALL) who did not receive the conditioning regimen recommended by the RCT (fludarabine 75 mg/m2, total body irradiation 12 Gy, cyclophosphamide 120 mg/kg). The results of our RCT appear to be reproducible in real-world conditions, provided that the same cord blood selection criteria and conditioning regimen are used. OBJECTIVES AND STUDY DESIGN We compared the characteristics and outcomes of RCT participants (n = 137) to a Francophone population-based registry of patients (real-world (RW) group) fulfilling the eligibility criteria used in our RCT and transplanted with one or two UCB units after a myeloablative conditioning (MAC) regimen between March 2015 (end of inclusion in the RCT) and February 2019 (n = 141). The primary endpoint was the two-year cumulative incidence (CI) of transplantation strategy failure as defined in our RCT. RESULTS The two groups were comparable in terms of age, disease distribution, hematologic status at transplantation, follow-up, and HLA compatibility. Patients in the RW group were more likely to be transplanted with a single-unit UCB (87.9% versus 49.6%, p < 0.001) and to receive a radiation-free regimen (39.0% vs. 60.6%, p < 0.001). The two-year CI of transplantation strategy failure, TRM, and the two-year probability of OS were similar between the two groups, although the relapse risk was higher in the RW group (31.2% ± 7.7% vs. 20.4% ± 6.8%, p = 0.01), resulting in a significantly lower DFS (59.2% ± 8.4% vs. 69.3% ± 8.0%, p = 0.047). This difference remained statistically significant only in the group of patients with acute lymphoid leukemia (ALL) who did not receive the conditioning regimen recommended by the RCT (fludarabine 75 mg/m2, total body irradiation 12 Gy, cyclophosphamide 120 mg/kg). CONCLUSION The results of our RCT appear to be reproducible in real-world conditions, provided that the same cord blood selection criteria and conditioning regimen are used.
PICO Summary
Population
Children, adolescents and young adults with acute leukaemia or myelodysplastic syndrome
Intervention
Participants in a randomised controlled trial (RCT) (n=137)
Comparison
Patients from a real-world cohort reported to a Francohpone regisistry, receiving onr or two cord blood units after myeloablative conditioning (RW group, n=141)
Outcome
The two groups were comparable in terms of age, disease distribution, hematologic status at transplantation, follow-up, and HLA compatibility. Patients in the RW group were more likely to be transplanted with a single-unit UCB (87.9% versus 49.6%) and to receive a radiation-free regimen (39.0% vs. 60.6%). The two-year CI of transplantation strategy failure, Transplant related mortality, and the two-year probability of overall survival were similar between the two groups, although the relapse risk was higher in the RW group (31.2% ± 7.7% vs. 20.4% ± 6.8%), resulting in a significantly lower DFS (59.2% ± 8.4% vs. 69.3% ± 8.0%). This difference remained statistically significant only in the group of patients with acute lymphoid leukemia (ALL) who did not receive the conditioning regimen recommended by the RCT (fludarabine 75 mg/m2, total body irradiation 12 Gy, cyclophosphamide 120 mg/kg).
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Busulfan-cyclophosphamide versus cyclophosphamide-busulfan as conditioning regimen before allogeneic hematopoietic cell transplantation: a prospective randomized trial
Seydoux, C., Medinger, M., Gerull, S., Halter, J., Heim, D., Chalandon, Y., Levrat, S. M., Schanz, U., Nair, G., Ansari, M., et al
Annals of hematology. 2020
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Abstract
Busulfan and cyclophosphamide (BuCy) is a frequently used myeloablative conditioning regimen for allogeneic hematopoietic cell transplantation (allo-HCT). Theoretical considerations and pharmacological data indicate that application of busulfan prior to subsequent cyclophosphamide (BuCy) may trigger liver toxicity. Reversing the order of application to cyclophosphamide-busulfan (CyBu) might be preferable, a hypothesis supported by animal data and retrospective studies. We performed a prospective randomized trial to determine impact of order of application of Bu and Cy before allo-HCT in 70 patients with hematological malignancy, 33 patients received BuCy and 37 CyBu for conditioning. In the short term, there were minimal differences in liver toxicity favoring CyBu over BuCy, significant only for alanine amino transferase at day 30 (p = 0.03). With longer follow-up at 4 years, non-relapse mortality (6% versus 27%, p = 0.05) was lower and survival (63% versus 43%, p = 0.06) was higher with CyBu compared to BuCy. Other outcomes, such as engraftment (p = 0.21), acute and chronic graft-versus-host disease (p = 0.40; 0.36), and relapse (p = 0.79), were similar in both groups. We prospectively show evidence that the order of application of Cy and Bu in myeloablative conditioning in allo-HCT patients has impact on outcome.
PICO Summary
Population
Patients with haematological malignancy (n=70)
Intervention
Busulfan-cyclophosphamide conditioning (BuCy, n=33)
Comparison
Cyclophosphamide-busulfan conditioning(CyBu, n=37)
Outcome
In the short term, there were minimal differences in liver toxicity favoring CyBu over BuCy, significant only for alanine amino transferase at day 30. With longer follow-up at 4 years, non-relapse mortality (6% versus 27%) was lower and survival (63% versus 43%) was higher with CyBu compared to BuCy. Other outcomes, such as engraftment acute and chronic graft-versus-host disease, and relapse, were similar in both groups.
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Total Body Irradiation or Chemotherapy Conditioning in Childhood ALL: A Multinational, Randomized, Noninferiority Phase III Study
Peters, C., Dalle, J. H., Locatelli, F., Poetschger, U., Sedlacek, P., Buechner, J., Shaw, P. J., Staciuk, R., Ifversen, M., Pichler, H., et al
Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2020;:Jco2002529
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Editor's Choice
Abstract
PURPOSE 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. PATIENTS AND METHODS FORUM is a randomized, controlled, open-label, international, multicenter, phase III, noninferiority study. Patients = 18 years at diagnosis, 4-21 years at HSCT, in complete remission pre-HSCT, and with an HLA-compatible related or unrelated donor were randomly assigned to myeloablative conditioning with fractionated 12 Gy TBI and etoposide versus fludarabine, thiotepa, and either busulfan or treosulfan. The noninferiority margin was 8%. With 1,000 patients randomly assigned in 5 years, 2-year minimum follow-up, and one-sided alpha of 5%, 80% power was calculated. A futility stopping rule would halt random assignment if chemoconditioning was significantly inferior to TBI (EudraCT: 2012-003032-22; ClinicalTrials.gov: NCT01949129). RESULTS Between April 2013 and December 2018, 543 patients were screened, 417 were randomly assigned, 212 received TBI, and 201 received chemoconditioning. The stopping rule was applied on March 31, 2019. The median follow-up was 2.1 years. In the intention-to-treat population, 2-year overall survival (OS) was significantly higher following TBI (0.91; 95% CI, 0.86 to 0.95; P < .0001) versus chemoconditioning (0.75; 95% CI, 0.67 to 0.81). Two-year cumulative incidence of relapse and treatment-related mortality were 0.12 (95% CI, 0.08 to 0.17; P < .0001) and 0.02 (95% CI, < 0.01 to 0.05; P = .0269) following TBI and 0.33 (95% CI, 0.25 to 0.40) and 0.09 (95% CI, 0.05 to 0.14) following chemoconditioning, respectively. CONCLUSION Improved OS and lower relapse risk were observed following TBI plus etoposide compared with chemoconditioning. We therefore recommend TBI plus etoposide for patients > 4 years old with high-risk ALL undergoing allogeneic HSCT.
Clinical Commentary
Dr. Julia Wolf, University Hospitals Bristol and Weston NHS Foundation Trust
What is known?
Allogeneic haematopoietic stem cell transplantation (HSCT) provides a potential curative treatment option for paediatric patients with high risk acute lymphoblastic leukaemia (ALL). Pre-transplant conditioning regimes with total body irradiation (TBI) have resulted in encouraging overall and relapse-free survival but may cause serious long-term side effects. As a result, several studies have investigated TBI-free regimes. A large meta-analysis (1) which included seven randomised controlled trials comparing TBI-based with chemoconditioning regimes demonstrated significantly lower treatment related mortality (TRM) but no overall survival (OS) advantage with TBI-based regimes. A further small randomised study (2) found significantly higher event-free survival (EFS) with TBI-based regimes in patients with unrelated donors, but a non-significant difference only in patients with matched sibling donors. Concerns about late effects of TBI on growth, cognitive function and secondary malignancy however remain. A single centre retrospective study (3) in paediatric ALL concluded that triosulphan based regimes were safe and efficacious while a similar review (4) in adult patients suggested that busulphan and clofarabine could provide an alternative to TBI. This paper reports on the FORUM study. It compares TBI with chemoconditioning regimes to investigate whether optimal chemoconditioning regimens could replace TBI in paediatric patients with high-risk ALL.
What did this paper set out to examine?
This is the largest randomised, controlled, open-label, international, multicentre, phase III trial comparing TBI plus etoposide with chemoconditioning (fludarabine, thiotepa and busulfan or triosulfan) in paediatric ALL to date. It investigates whether chemoconditioning is non-inferior to TBI-based regimes with the primary endpoint of OS. It is also the first study to directly and prospectively compare these regimes in terms of disease-free survival and short- and long-term adverse events. The study aimed to recruit 1000 patients.
What did they show?
Improved OS and lower relapse risk were observed following TBI plus etoposide compared with chemoconditioning. Patients ≤18 years old at diagnosis and aged 4-21 at HSCT with high risk ALL in complete morphological remission with HLA compatible related or unrelated donor were included in the study. Patients were randomised 1:1 to 12Gy TBI with etoposide versus fludarabine, thiotepa and busulfan or triosulphan conditioning. Patients were well matched for baseline characteristics and demographics. Randomisation was stopped early due significant inferiority of chemoconditioning compared with TBI-based regime.
Results
Following randomisation of 417 patients, a futility stopping rule was applied because patients receiving chemoconditioning with fludarabine, thiotepa, and busulfan or treosulfan had inferior OS to those receiving TBI plus etoposide. Two-year OS was 0.91 (95% CI, P <.0001) following TBI versus 0.75 (95% CI) following chemoconditioning. Median follow up was 2.1 years. Relapse was the commonest reason for treatment failure and out of 67 patients who relapsed, there was no difference in OS between conditioning regimes. There was no difference in serious adverse events or GvHD rates between the groups.
What are the implications for practice and for future work?
While TBI is associated with potentially serious long-term side effects, this study supports growing evidence demonstrating improved outcomes for patients undergoing TBI-based conditioning. Here patients receiving TBI-based conditioning had a significantly lower risk of relapse and TRM than those given chemoconditioning.
Of note, TRM in this trial was low compared to previously reported studies. FOCUS reported a 2-year OS and EFS rate of 0.91 and 0.91 respectively, which is the lowest documented TRM in HSCT for high-risk paediatric ALL to date. Additionally, other risk factors thought to impact on outcomes (e.g. leukaemia phenotype, MRD pre-transplant, donor type, etc) were not found to be significant in FOCUS. Only remission status (CR1 vs CR2) and conditioning regime influenced OS and EFS. This may be in part explained by the strong attempts within this study to reduce MRD prior to HSCT in all patients.
This was a noninferiority study which required a sample size of 1000 patients with 2-year minimum follow-up to make analysis of primary outcomes feasible. As the majority of relapses in paediatric ALL occur in the first 24 months, it is unlikely that longer follow up would result in dramatic changes to outcomes.
Non-randomised recruitment in FORUM to assess long-term side effects of TBI, such as secondary malignancy, in FORUM is ongoing. However, no difference in adverse events or incidence of GvHD was found between study groups. The study reports a composite end point of 2-year GVHD-free, relapse-free survival of 72% (95% CI) following TBI plus etoposide and 51% (95% CI, p= .0003) following chemoconditioning which might be a benchmark for future investigations.
PICO Summary
Population
Patients diagnosed with acute lymphoblastic leukaemia at or before 18 years of age, who underwent HSCT aged 4-21 years (n=413)
Intervention
TBI conditioning (n=212)
Comparison
Chemoconditioning: fludarabine, thiotepa, and either busulfan or treosulfan (n=201)
Outcome
The median follow-up was 2.1 years. In the intention-to-treat population, 2-year overall survival (OS) was significantly higher following TBI (0.91) versus chemoconditioning (0.75). Two-year cumulative incidence of relapse and treatment-related mortality were 0.12 and 0.02 following TBI and 0.33 and 0.09 following chemoconditioning, respectively.