1.
Comparing transplant outcomes in ALL patients after haploidentical with PTCy or matched unrelated donor transplantation
Al Malki, M. M., Yang, D., Labopin, M., Afanasyev, B., Angelucci, E., Bashey, A., Socie, G., Karduss-Urueta, A., Helbig, G., Bornhauser, M., et al
Blood advances. 2020;4(9):2073-2083
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Abstract
We compared outcomes of 1461 adult patients with acute lymphoblastic leukemia (ALL) receiving hematopoietic cell transplantation (HCT) from a haploidentical (n = 487) or matched unrelated donor (MUD; n = 974) between January 2005 and June 2018. Graft-versus-host disease (GVHD) prophylaxis was posttransplant cyclophosphamide (PTCy), calcineurin inhibitor (CNI), and mycophenolate mofetil (MMF) for haploidentical, and CNI with MMF or methotrexate with/without antithymoglobulin for MUDs. Haploidentical recipients were matched (1:2 ratio) with MUD controls for sex, conditioning intensity, disease stage, Philadelphia-chromosome status, and cytogenetic risk. In the myeloablative setting, day +28 neutrophil recovery was similar between haploidentical (87%) and MUD (88%) (P = .11). Corresponding rates after reduced-intensity conditioning (RIC) were 84% and 88% (P = .47). The 3-month incidence of grade II-IV acute GVHD (aGVHD) and 3-year chronic GVHD (cGVHD) was similar after haploidentical compared with MUD: myeloablative conditioning, 33% vs 34% (P = .46) for aGVHD and 29% vs 31% for cGVHD (P = .58); RIC, 31% vs 30% (P = .06) for aGVHD and 24% vs 29% for cGVHD (P = .86). Among patients receiving myeloablative regimens, 3-year probabilities of overall survival were 44% and 51% with haploidentical and MUD (P = .56). Corresponding rates after RIC were 43% and 42% (P = .6). In this large multicenter case-matched retrospective analysis, despite the limitations of a registry-based study (ie, unavailability of key elements such as minimal residual disease testing), our analysis indicated that outcomes of patients with ALL undergoing HCT from a haploidentical donor were comparable with 8 of 8 MUD transplantations.
Clinical Commentary
Dr. Julia Wolf, University Hospitals Bristol and Weston NHS Foundation Trust
What is known?
Allogeneic stem cell transplant is a potentially curative treatment option for adults with acute lymphoblastic leukaemia (ALL). Transplant outcomes are, amongst other factors, dependent on optimal donor selection; despite a plethora of recent advances, donor availability is an area of unmet need for many patients. A fully HLA matched sibling donor is the preferred donor choice but is available in <30% of patients. Several studies have shown that comparable results can be achieved with a fully matched unrelated donor (MUD), but availability can be as low as 20% in non-Caucasian individuals. Haploidentical donor options are available for the vast majority of patients but historically their utility was limited by high rates of GvHD, treatment related morbidity and mortality and graft rejection. The addition of post-transplant cyclophosphamide (PtCy), calcineurin inhibitors (CNI) and mycofenolate mofetil (MMF) as GvHD prophylaxis has reduced these risks and is now a frequently employed approach for haploidentical haematopoietic stem cell transplant (HaploSCT) making it an attractive alternative to conventional donor transplant.
Several recent studies have compared MUD alloSCT and HaploSCT approaches in ALL in recent years. Most notably this has included an analysis of the European Bone Marrow Transplant (EBMT) group registry which included 1234 patients with ALL and shows comparable outcomes between HaploSCT and MUD alloSCT.
What did this paper set out to examine?
This retrospective multicentre cohort study aims to compare outcomes of HaploSCT & PtCy with MUD alloSCT in ALL in terms of engraftment, acute and chronic graft versus host disease (GvHD) incidence and severity, relapse free survival (RFS), non-relapse mortality (NRM) and overall survival (OS).
It is the first study to explicitly compare haploidentical allogeneic stem cell transplant (HaploSCT) with matched unrelated donor allogeneic stem cell transplant (MUD alloSCT) in terms of conditioning intensity, Philadelphia chromosome status and graft source. It also provides additional extensive, multinational data with matched pair analysis on outcomes of patients in both groups.
What did they show?
The authors compared data from 1461 adult patients (HaploSCT = 487 vs MUD = 974). Data from two separate registries was used: the EBMT registry alone was used for MUD alloSCT while the Haploidentical Transplant and Cellular Therapy Research Consortium (TCT-RC) was used in combination with Acute Leukaemia Working Party subgroup of the EBMT registry data for assessment of HaploSCT. The reason for using two databases is not explicitly stated although it is believed that this was done to increase sample size in the HaploSCT cohort.
Patients >18 years old with ALL over a 13.5-year period from January 2005 to June 2018 receiving their first alloSCT were included in the analysis. Exclusion criteria were fairly selected. GvHD prophylaxis was with PtCy, CNI and MMF in the HaploSCT group and with CNI and methotrexate or MMF in the MUD group. 64% of MUD patients also received ATG. Cohorts were matched at 1:2 (HaploSCT : MUD) for sex, cytogenetic risk, Philadelphia chromosome status, disease stage and intensity of conditioning (reduced intensity vs myeloablative). Statistical analysis was appropriate for the question to be answered.
RESULTS: HaploSCT and MUD alloSCT were comparable in terms of neutrophil engraftment, RFS and OS regardless of conditioning intensity, Philadelphia chromosome status and graft source. 3-year OS was 44% in the HaploSCT group vs 51% in the MUD group using myeloablative conditioning (p=5.56) with rates of 43% (HaploSCT) and 42% (MUD) for reduced intensity conditioning (p=5.6).
The overall incidence of acute and chronic GvHD was similar between the groups but there was an increased incidence in grade III-IV GvHD in HaploSCT when peripheral blood stem cells were used. Additionally, mortality form GvHD was higher in the MUD group. This is in keeping with results reported in the literature.
What are the implications for practice and for future work?
HaploSCT is becoming an increasingly attractive option for patients without matched sibling transplant. The comparable overall survival and now much more manageable GvHD risk will afford a previously difficult to manage cohort of patients a further option of curative treatment.
This study adds to the growing evidence base but did have some limitations. Firstly, the study is retrospective and uses registry-based data. While the registries used are of high quality, there are inherent concerns about missing data points and differences between the two databases used. The authors agreed that the variability of the condition regimes used added a further layer of complexity.
Prospective data with intention to treat analysis is required to further assess the comparability of HaploSCT and MUD for ALL patients.
PICO Summary
Population
Adult patients with acute lymphoblastic leukaemia (n=1461)
Intervention
HSCT from a haploidentical donor (n = 487)
Comparison
HSCT from a matched unrelated donor (n = 974)
Outcome
In the myeloablative setting, day +28 neutrophil recovery was similar between haploidentical (87%) and MUD (88%). Corresponding rates after reduced-intensity conditioning (RIC) were 84% and 88%. The 3-month incidence of grade II-IV acute GVHD (aGVHD) and 3-year chronic GVHD (cGVHD) was similar after haploidentical compared with MUD: myeloablative conditioning, 33% vs 34% for aGVHD and 29% vs 31% for cGVHD; RIC, 31% vs 30% for aGVHD and 24% vs 29% for cGVHD. Among patients receiving myeloablative regimens, 3-year probabilities of overall survival were 44% and 51% with haploidentical and MUD. Corresponding rates after RIC were 43% and 42%.
2.
Haploidentical Transplantation with Post-Transplantation Cyclophosphamide for High-Risk Acute Lymphoblastic Leukemia
Srour, S. A., Milton, D. R., Bashey, A., Karduss-Urueta, A., Al Malki, M. M., Romee, R., Solomon, S., Nademanee, A., Brown, S., Slade, M., et al
Biology of Blood & Marrow Transplantation. 2017;23(2):318-324
Abstract
Haploidentical transplantation performed with post-transplantation cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis has been associated with favorable outcomes for patients with acute myeloid leukemia and lymphomas. However, it remains unclear if such approach is effective for patients with acute lymphoblastic leukemia (ALL). We analyzed outcomes of 109 consecutively treated ALL patients 18 years of age and older at 5 institutions. The median age was 32 years and the median follow-up for survivors was 13 months. Thirty-two patients were in first complete remission (CR1), while the rest were beyond CR1. Neutrophil engraftment occurred in 95% of the patients. The cumulative incidences of grades II to IV and III and IV acute GVHD at day 100 after transplantation were 32% and 11%, respectively, whereas chronic GVHD, nonrelapse mortality, relapse rate, and disease-free survival (DFS) at 1 year after transplantation were 32%, 21%, 27%, and 51%, respectively. Patients in CR1 had 52% DFS at 3 years. These results suggest that haploidentical transplants performed with PTCy-based GVHD prophylaxis provide a very suitable alternative to HLA-matched transplantations for patients with ALL.