Post-transplant cyclophosphamide containing regimens after matched sibling, matched unrelated and haploidentical donor transplants in patients with acute lymphoblastic leukemia in first complete remission, a comparative study of the ALWP of the EBMT

Impact of CD34 positive cell dose in donor graft on the outcomes after haploidentical peripheral blood stem cell transplantation with post-transplant cyclophosphamide - A retrospective single-center study with a Japanese cohort

BACKGROUND

Haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) with post-transplant cyclophosphamide (PTCy) is an important therapeutic option for patients lacking an HLA-matched donor. However, the significance of CD34+ cell dose in grafts has not been fully elucidated.

OBJECTIVE

We aimed to explore the impact of CD34+ cell dose on outcomes after haplo-PBSCT with PTCy.

STUDY DESIGN

We retrospectively investigated 111 consecutive patients who underwent haplo-PBSCT with PTCy or HLA-matched PBSCT from related donors.

RESULTS

There were no statistically significant differences in 3-year overall survival (p = 0.559) or progression-free survival (p = 0.974) between haplo-PBSCT and matched PBSCT. Delayed neutrophil engraftment and a lower incidence of graft-versus-host disease were observed in haplo-PBSCT. The median dose of CD34+ cells was 4.9 × 106 /kg in 57 haplo-PBSCT and 4.5 × 106 /kg in 54 matched PBSCTs. Importantly, patients who underwent haplo-PBSCT with the administration of CD34+ cell at a dose of ≥4.0 × 106 /kg significantly had improved OS (p = 0.015) and decreased incidence of disease relapse (p = 0.001) without increasing incidence of GVHD.

CONCLUSION

Our data suggest that a higher dose of CD34+ cells in haplo-PBSCT with PTCy positively impacts the outcomes without an increase of GVHD.

Graft-versus-Host Disease Prophylaxis with Post- Transplantation Cyclophosphamide in Chronic Myeloid Leukemia Patients Undergoing Allogeneic Hematopoietic Cell Transplantation from an Unrelated or Mismatched Related Donor: A Comparative Study from the Chronic Malignancies Working Party of the EBMT (CMWP-EBMT)

Outcomes following allogeneic hematopoietic cell transplantation (allo-HCT) for chronic myeloid leukemia (CML) with post-transplantation cyclophosphamide (PTCy) using an unrelated donor (UD) or a mismatched related donor (MMRD) remain unknown. We report a retrospective comparison of PTCy-based allo-HCT from a UD, non-PTCy allo-HCT from a UD, and PTCy allo-HCT from an MMRD. Inclusion criteria were adult patients with CML undergoing first allo-HCT between 2012 and 2019 from a UD with either PTCy or non-PTCy graft-versus-host disease (GVHD) prophylaxis or from an MMRD using PTCy. The primary endpoint was GVHD-free/relapse-free survival (GRFS). A total of 1341 patients were included (82% in the non-PTCy UD cohort). With a median follow-up of 34.9 months, the 3-year GRFS was 43% in the non-PTCy cohort, 37% in the PTCy-UD cohort, and 39% PTCy-MMRD cohort (P = .15). Multivariable analyses revealed no significant differences among the 3 cohorts in terms of overall survival (OS), progression-free survival, RI, and nonrelapse mortality. Factors independently associated with worse OS in the overall cohort were Karnofsky Performance Status <90 (hazard ratio [HR], 1.86; 95% confidence interval [CI], 1.41 to 2.45; P < .001), older age (HR, 1.24, 95% CI, 1.11 to 1.38; P < .001), and disease stage (compared to chronic phase [CP] 1): blast phase (HR, 2.25; 95% CI, 1.60 to 3.16; P < .001), accelerated phase (HR, 1.63; 95% CI, 1.05 to 2.54; P = .03), and CP >2 (HR, 1.58; 95% CI, 1.15 to 2.17; P = .005). These results suggest that allo-HCT in patients with CML using either a UD or an MMRD with PTCy-based GVHD prophylaxis are feasible transplantation, platforms and that the disease stage at allo-HCT remains a major prognostic factor, highlighting the importance of closely monitoring CML patients and proposing transplantation when indicated when still in CP1.

The current landscape: Allogeneic hematopoietic stem cell transplant for acute lymphoblastic leukemia

One of the consistent features in development of hematopoietic stem cell transplant (HCT) for Acute Lymphoblastic Leukemia (ALL) is the rapidity with which discoveries in the laboratory are translated into innovations in clinical care. Just a few years after murine studies demonstrated that rescue from radiation induced marrow failure is mediated by cellular not humoral factors, E. Donnall Thomas reported on the transfer of bone marrow cells into irradiated leukemia patients. This was followed quickly by the first descriptions of Graft versus Leukemia (GvL) effect and Graft versus Host Disease (GvHD). Despite the pivotal nature of these findings, early human transplants were uniformly unsuccessful and identified the challenges that continue to thwart transplanters today - leukemic relapse, regimen related toxicity, and GvHD. While originally only an option for young, fit patients with a matched family donor, expansion of the donor pool to include unrelated donors, umbilical cord blood units, and more recently the growing use of haploidentical donors have all made transplant a more accessible therapy for patients with ALL. Novel agents for conditioning, prevention and treatment of GvHD have improved outcomes and investigators continue to develop novel treatment strategies that balance regimen related toxicity with disease control. Our evolving understanding of how to prevent and treat GvHD and how to prevent relapse are incorporated into novel clinical trials that are expected to further improve outcomes. Here we review current considerations and future directions for both adult and pediatric patients undergoing HCT for ALL, including indication for transplant, donor selection, cytoreductive regimens, and outcomes.

Second haploidentical stem cell transplantation (HAPLO-SCT2) after relapse from a first HAPLO-SCT in acute leukaemia-a study on behalf of the Acute Leukaemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT)

For patients with acute myeloid and lymphoblastic leukaemia (AML/ALL) lacking a matched sibling or unrelated donor, haploidentical stem cell transplantation (HAPLO-SCT) is increasingly used. However, available data on the treatment of relapse after HAPLO-SCT, including feasibility and efficacy of a second HAPLO-SCT (HAPLO-SCT2), is scarce. Hence, adults with AML/ALL, that had undergone HAPLO-SCT2 without ex-vivo manipulation after haematologic relapse from HAPLO-SCT1 were selected for a retrospective registry analysis. Eighty-two patients (AML, n = 63, ALL, n = 19, median follow-up: 33 months) were identified. Engraftment rate was 87%. At day +180, cumulative incidences of acute GvHD II-IV°/chronic GvHD were 23.9%/22.6%, respectively. Two-year overall survival/leukaemia-free survival (OS/LFS) were 34.3%/25.4%; 2-year non-relapse mortality (NRM) and relapse incidence (RI) were 17.6% and 57%. Leukaemia was the most frequent cause of death. Separated by disease, 2-year OS/LFS/NRM/RI were 28.7%/22.3%/16.2%/61.6% in AML, and 55.3%/38.4%/23.5%/38.2% in ALL patients. In a risk-factor analysis among patients with AML, stage at HAPLO-SCT1 and HAPLO-SCT2, and interval from HAPLO-SCT1 to relapse significantly influenced outcome. Our data demonstrate that HAPLO-SCT2 is a viable option in acute leukaemia relapse after HAPLO-SCT1. Engraftment, toxicity, risk factors and long-term outcome are comparable to data reported after allo-SCT2 in a matched donor setting.

Benchmarking of survival outcomes following Haematopoietic Stem Cell Transplantation (HSCT): an update of the ongoing project of the European Society for Blood and Marrow Transplantation (EBMT) and Joint Accreditation Committee of ISCT and EBMT (JACIE)

From 2016 EBMT and JACIE developed an international risk-adapted benchmarking program of haematopoietic stem cell transplant (HSCT) outcome to provide individual EBMT Centers with a means of quality-assuring the HSCT process and meeting FACT-JACIE accreditation requirements relating to 1-year survival outcomes. Informed by previous experience from Europe, North America and Australasia, the Clinical Outcomes Group (COG) established criteria for patient and Center selection, and a set of key clinical variables within a dedicated statistical model adapted to the capabilities of the EBMT Registry. The first phase of the project was launched in 2019 to test the acceptability of the benchmarking model through assessment of Centers' performance for 1-year data completeness and survival outcomes of autologous and allogeneic HSCT covering 2013-2016. A second phase was delivered in July 2021 covering 2015-2019 and including survival outcomes. Reports of individual Center performance were shared directly with local principal investigators and their responses were assimilated. The experience thus far has supported the feasibility, acceptability and reliability of the system as well as identifying its limitations. We provide a summary of experience and learning so far in this 'work in progress', as well as highlighting future challenges of delivering a modern, robust, data-complete, risk-adapted benchmarking program across new EBMT Registry systems.

First-line steroid-free systemic treatment of acute and chronic graft-versus-host disease after novel prophylaxis regimens

In the early randomized trials the efficacy of calcineurin inhibitors (CNI) in the treatment of graft-versus-host disease (GVHD) was comparable to corticosteroids (CS), but these results became obsolete with the introduction of CNIs in prophylaxis. Recently several effective CNI-free GVHD prophylaxis regimens were introduced based on posttransplantation cyclophosphamide (PTCY) and αβ ex vivo T-cell depletion (αβ-TCD). Among patients treated under these protocols 34 patients with grade II-IV acute (aGVHD) and 40 with moderate and severe chronic (cGVHD) disease were treated with CNIs or other CS-free regimens as the first line. Overall response rate (ORR) was significantly higher in cGVHD than in aGVHD: 80% (95% CI 68-92) vs 47% (95% CI 30-64%), p = 0.0031. In aGVHD it was almost completely restricted to isolated stage III skin GVHD. In cGVHD patients with moderate disease ORR was higher than in severe: 96% (95% CI 88-100%) vs 56% (95%CI 32-81%), p = 0.0022. Two-year overall survival was 76% (95% CI 58-87%) in aGVHD and 95% (95% CI 81-99%) in cGVHD. Failure-free survival was 21% (95% CI 9-37%) in aGVHD and 81% (95% CI 64-91%) in cGVHD. Patients responding to steroid-free regimens had lower use of systemic antibiotics (p = 0.0095), antifungals (p = 0.0319) and antivirals (p < 0.0001).

Hematopoietic Stem Cell Transplantation Activity in China 2020-2021 During the SARS-CoV-2 Pandemic: A Report From the Chinese Blood and Marrow Transplantation Registry Group

Between 2020 and 2021, 31,525 hematopoietic stem cell transplantations (HSCTs) were reported to the Chinese Blood and Marrow Transplantation Registry Group throughout mainland China. In this report, we describe the activity and current trends for HSCT in China during the SARS-CoV-2 pandemic. In 2020, a total of 13,415 cases of HSCT were reported from 166 transplantation teams, and 75% (10,042 cases) were allogeneic HSCTs. In 2021, a total of 18,110 cases of HSCT were reported from 174 transplantation teams, and 70% (12,744 cases) were allogeneic HSCTs. Haploidentical donor (HID) transplantation accounted for 63% (7977 cases) of allogeneic HSCTs in 2021. The most common indications for allogeneic HSCT for malignant disease were acute myeloid leukemia (37%) and acute lymphoblastic leukemia (23%), and the largest proportion of nonmalignant disease comprised aplastic anemia (13%). The peripheral blood stem cell source accounted for 41% of HIDs and 75% of matched sibling donors. The BuCy-based regimen (57%) was the most popular conditioning regimen for allogeneic HSCT, followed by the BuFlu-based regimen (28%) and total body irradiation-based regimen (11%). This survey provides comprehensive information about the current activities and might benefit clinical physicians' decision planning for HSCT.

Impact of Post-Transplantation Cyclophosphamide on Transfusion Requirements in HLA-Matched Sibling Peripheral Blood Stem Cell Transplantation

Post-transplantation cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis is being increasingly used in allogeneic hematopoietic stem cell transplantation (allo-HSCT) from HLA-matched related donors (MRDs); however, information regarding the transfusion needs in this setting is lacking. This study compared RBC and platelet units transfused and time to transfusion independence according to the GVHD prophylaxis regimen in MRD HSCT. We performed a matched-pair analysis comparing the transfusion requirements and the clinical outcomes of patients who underwent MRD peripheral blood HSCT using PTCy between January 2017 and June 2021 (n = 100) with historical MRD HSCTs using standard cyclosporine A (CsA)-based prophylaxis (n = 100). Neutrophil engraftment was significantly delayed in the PTCy group compared with the CsA group (16 days versus 13 days; P = .003). PTCy was associated with increased RBC (median, 5 units versus 4 units; P = .04) and platelet (median, 6 units versus 3 units; P = .01) transfusion requirements during the first 30 days after transplantation. The proportion of patients requiring platelet transfusion during days 31 to 90 after transplantation was also higher in the PTCy group (55% versus 25%; P < .0001). In multivariate analysis, PTCy was associated with delayed RBC and platelet transfusion independence (hazard ratio, .61 [P = .007] and .51 [P < .0001], respectively). The cumulative incidence (CuI) of BK polyomavirus-associated hemorrhagic cystitis grade ≥2 at 100 days was higher in the PTCy group (34% versus 12%; P < .0001); however, the PTCy group had lower rates of grade II-IV acute GVHD (100-day CuI, 57% versus 23%; P < .0001) and moderate to severe chronic GVHD (1-year CuI, 49% versus 28%; P = .003), as well as better 2-year overall survival (74% versus 56%; P = .01). Our study shows that although PTCy increases the transfusion burden in MRD HSCT, it is associated with a low incidence of severe GVHD and with encouraging survival outcomes.

Haploidentical Versus Matched Sibling Donor Hematopoietic Stem Cell Transplantation for Adult Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia: A Study From the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

The results of haploidentical stem cell transplantation (haploHCT) for patients with acute lymphoblastic leukemia (ALL) transplanted in active disease remain largely unknown. We retrospectively analyzed adult patients with R/R ALL who underwent haploHCT or matched sibling donor (MSD-HCT) as a first transplantation between 2012 and 2020. The analysis comprised 274 patients, 94 had a haploHCT, and 180 had an MSD-HCT. The median follow-up was 32 months. The median age was 33 (range 18-76) and 37 (18-76) years in the haplo- and MSD-HCT groups, respectively. Post-transplant cyclophosphamide (PTCy) was used in 88% of haploHCT and in 4% of the MSD-HCT group. Graft-versus-host disease grade III-IV was higher in haploHCT than in the MSD-HCT group (18% versus 9%; P = 0.042). The 2-year chronic (c) graft-versus-host disease rates were 17% versus 33% (hazard ratio [HR] = 0.56; P = 0.14), respectively. By multivariate analysis, relapse incidence, and leukemia-free survival were not significatively different between the transplant groups, while nonrelapse mortality (NRM) was significantly higher (25% versus 18% at 2 years; HR = 2.03; P = 0.042) and overall survival (OS) lower (22% versus 38% at 2 years; HR = 1.72; P = 0.009) in the haploHCT group compared with the MSD-HCT group. We conclude that the 2-year OS of R/R ALL patients undergoing MSD transplants is significantly better than in haploHCT with a higher NRM in the latter.

Systematic overview of HLA-matched allogeneic hematopoietic cell transplantation with post-transplantation cyclophosphamide

The successful application of post-transplantation cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis in HLA-haploidentical allogeneic hematopoietic cell transplantation (allo-HCT) led to the expansion of its application to HLA-matched related and unrelated allo-HCT. Notably, single-agent PTCy was found to be feasible for GVHD prevention in HLA-matched bone marrow transplantation. Single-agent PTCy prophylaxis was later attempted to control GVHD in HLA-matched peripheral blood stem cell transplantation (PBSCT), but this approach was inadequate to alleviate GVHD as evidenced by the high incidence of severe GVHD and/or non-relapse mortality. Therefore, various combinations of immunosuppressants with PTCy have been explored to identify the optimal drug combination that would efficiently prevent GVHD in HLA-matched PBSCT. A recent murine study helped clarify the putative mechanism underlying the activity of PTCy, demonstrating that PTCy impairs the proliferation and function of alloreactive T cells from the donor, but does not eliminate alloreactive T cells altogether. In addition, imbalanced reconstitution of NK cell as well as T cells has been observed in HLA-haploidentical allo-HCT. Therefore, it remains unclear whether or not PTCy-containing GVHD prophylaxis should replace the classical GVHD prophylaxis regimen in the HLA-matched setting, and convincing evidence supporting the benefits of PTCy is needed.

SOHO State of the Art Updates and Next Questions: Novel Transplant and Post-Transplant Options in Acute Lymphoblastic Leukemia

Allogeneic hematopoietic cell transplantation (alloHCT) is a potentially curative treatment approach for patients with high-risk acute lymphoblastic leukemia (ALL). Despite development of several novel therapies targeting B-cell ALL, alloHCT continues to play an essential role in management, but the identification of patients who are most likely to benefit from alloHCT in first or subsequent remissions continues to evolve. Broader donor options, including haploidentical donors and umbilical cord blood, have enabled alloHCT for more patients, but improvements in front-line therapy and increasing use of high-sensitivity measurable residual disease (MRD) quantification continue to modify the calculus for selecting which patients require transplantation. MRD quantification has become increasingly important as a prognostic indicator, as well as a trigger for therapeutic intervention, since the achievement of MRD negative complete remission is well-established to be associated with improved transplant outcomes. ALL remains the only malignancy with approved therapy for MRD positivity after achievement of remission, and use of Blinatumomab in this setting currently appears to be most effective when used as a bridge-to-transplant, rather than a destination or purely consolidative therapy. Expanding options for those with relapsed/refractory disease, including chimeric antigen receptor (CAR)-T cells, also render more patient in suitably deep remissions to enable alloHCT with a high likelihood of success. It remains unclear whether CAR-T cell therapies may obviate the need for alloHCT in some patients, and currently available data suggest there remains a role for alloHCT after CAR-T. Together, these therapeutic advances appear to be improving post-transplant outcomes. Nevertheless, more remains to be studied regarding how to optimize use of available and emerging cellular and immune modulating therapies to maximize the likelihood of long-term post-alloHCT remission in high-risk ALL.

HLA-Matching with PTCy: A Reanalysis of a CIBMTR Dataset with Propensity Score Matching and Donor Age

A reanalysis including donor age and using propensity score matching shows no major differences in survival or relapse.

Data sharing and collaborative reanalysis enhance our recognition of the nuances of complex statistical methodologies and published results.

Blood or marrow transplantation (BMT) outcomes using haploidentical donors (Haplo) and posttransplant cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis compare favorably to HLA-matched donors using calcineurin inhibitor–based prophylaxis. A recent Center for International Blood and Marrow Transplant Research analysis of patients receiving homogenous PTCy-based prophylaxis found that, with reduced intensity conditioning, Haplo BMTs had worse outcomes than matched unrelated donor (MUD) BMTs. Due to significant differences between groups, we reanalyzed the dataset using propensity score matching and, additionally, added a donor age variable. After matching MUD BMTs to Haplo BMTs in a 1:5 ratio, no significant differences were found between groups across all measured baseline characteristics. Outcomes analyses demonstrated no significant differences in overall survival (hazard ratio [HR] of mortality with MUD vs Haplo [95% confidence interval], 0.95 [0.65-1.16], P = .75), disease-free survival (HR of relapse or death, 0.98 [0.73-1.18], P = .89), relapse rate (HR, 1.06 [0.77-1.38], P = .69), or nonrelapse mortality (NRM) (HR, 0.85 [0.42-1.13], P = .49) between groups. After stratification by conditioning intensity, MUD BMTs in the reduced-intensity cohort had lower risk of NRM (HR, 0.56 [0.14-0.99], P = .05), with no significant difference in other clinical outcomes. These results suggest the effect of HLA matching on BMT outcomes with PTCy is less meaningful than previously reported. Timely identification of a young, at least half-matched (related or unrelated) donor may be more important than finding a fully matched donor if the latter leads to a delay in BMT or use of an older donor.

Haploidentical vs Matched Unrelated vs Matched Sibling Donor HCT with Post-Transplantation Cyclophosphamide

With the use of post-transplantation cyclophosphamide (PTCy), the outcomes of mismatched related donor hematopoietic cell transplantation (HCT) are now approaching those of matched donor HCT. Here we compared haploidentical donor HCT versus HLA-matched unrelated donor (MUD) HCT and HLA-identical sibling donor (MSD) HCT in a cohort in which all patients received PTCy for graft-versus-host disease (GVHD) prophylaxis. We included 661 patients (275 haploidentical, 246 MUD, and 140 MSD HCT). The most common diagnoses were acute myelogenous leukemia and myelodysplastic syndrome. In multivariate analysis, the haploidentical group was found to have significantly higher nonrelapse mortality (NRM) (hazard ratio [HR], 3.2; 95% confidence interval [CI], 2 to 4.9; P < .001) and inferior progression-free survival (HR, 1.8; 95% CI, 1.4 to 2.4; P < .001) and overall survival (OS; HR, 2.2; 95% CI, 1.6 to 3; P < .001) compared with the MUD group. Relapse was the most common cause of death in all groups. Among causes of NRM, the haploidentical group had more infection-related deaths and fewer GVHD-related deaths than the other groups. The haploidentical group also had a higher risk of viral and fungal infections, grade ≥3 hemorrhagic cystitis, and cardiovascular toxicities and slower reconstitution of CD4, CD8, and regulatory T cells but faster reconstitution of natural killer cells. In an exploratory analysis, older patients with older donors (>50 years for both) appeared to have particularly high NRM and lower OS in the haploidentical group compared with the other groups. Our data suggest that even with the use of PTCy, the outcomes of haploidentical HCT are inferior to those of HLA-matched donor HCT.

Mesenchymal stromal cells plus basiliximab, calcineurin inhibitor as treatment of steroid-resistant acute graft-versus-host disease: a multicenter, randomized, phase 3, open-label trial

Background

Steroid-resistant (SR) acute graft-versus-host disease (aGVHD) lacks standard second-line treatment. Mesenchymal stromal cells (MSCs) have potential efficacy in SR aGVHD. We aimed to assess the efficacy and safety of MSCs combined with basiliximab and calcineurin inhibitor as second-line therapy for SR aGVHD.

Methods

A randomized phase 3 trial involved 203 SR aGVHD patients at nine centers in China (September 2014–March 2019). Participants were randomized at a 1:1 ratio to receive second-line therapy with (n = 101) or without (n = 102) MSCs. The primary endpoint was the overall response (OR) at day 28. Secondary and safety endpoints included durable OR at day 56, failure-free survival, overall survival (OS), chronic GVHD (cGVHD), infection, hematological toxicity and relapse.

Results

Of 203 patients, 198 (97.5%; mean age, 30.1 years; 40.4% women) completed the study. The OR at day 28 was higher in the MSC group than the control group (82.8% [82 patients] vs. 70.7% [70]; odds ratio, 2.00; 95% confidence interval [CI], 1.01–3.94; P = 0.043). The durable OR at day 56 was also higher in the MSC group (78.8% [78 patients] vs. 64.6% [64]; odds ratio, 2.02; 95% CI, 1.08–3.83; P = 0.027). The median failure-free survival was longer in the MSC group compared with control (11.3 months vs. 6.0 months; hazard ratio (HR) 0.68; 95% CI, 0.48–0.95, P = 0.024). The 2-year cumulative incidence of cGVHD was 39.5% (95% CI, 29.3–49.4%) and 62.7% (51.4–72.1%) in the MSC and control groups (HR 0.55, 95% CI, 0.36–0.84; P = 0.005). Within 180 days after study treatments, the most common grade 3 and 4 adverse events were infections (65 [65.7%] in the MSC group vs. 78 [78.8%] in the control group) and hematological toxicity (37 [37.4%] vs. 53 [53.5%]). The 3-year cumulative incidence of tumor relapse was 10.1% (95% CI, 5.2–17.1) and 13.5% (7.5–21.2%) in the MSC and control groups, respectively (HR 0.75, 95% CI, 0.34–1.67, P = 0.610).

Conclusions

MSCs plus second-line treatments increase the efficacy of SR aGVHD, decrease drug toxicity of second-line drugs and cGVHD without increasing relapse, and are well-tolerated. MSCs could be recommended as a second-line treatment option for aGVHD patients.

Trial registration clinicaltrials.gov identifier: NCT02241018. Registration date: September 16, 2014, https://clinicaltrials.gov/ct2/show/NCT02241018.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-022-01240-4.

Total body irradiation plus fludarabine versus thiotepa, busulfan plus fludarabine as a myeloablative conditioning for adults with acute lymphoblastic leukemia treated with haploidentical hematopoietic cell transplantation. A study by the Acute Leukemia Working Party of the EBMT

Optimal conditioning for adults with acute lymphoblastic leukemia (ALL) treated with haploidentical hematopoietic cell transplantation (haplo-HCT) and post-transplant cyclophosphamide has not been established so far. We retrospectively compared outcomes for two myeloablative regimens: fludarabine + total body irradiation (Flu-TBI, n = 117) and thiotepa + iv. busulfan + fludarabine (TBF, n = 119). Patients transplanted either in complete remission (CR) or with active disease were included in the analysis. The characteristics of both groups were comparable except for patients treated with TBF were older. In univariate analysis the incidence of non-relapse mortality (NRM) at 2 years was increased for TBF compared to Flu-TBI (31% vs. 19.5%, p = 0.03). There was a tendency towards reduced incidence of relapse after TBF (p = 0.11). Results of multivariate analysis confirmed a reduced risk of NRM using Flu-TBI (HR = 0.49, p = 0.03). In the analysis restricted to patients treated in CR1 or CR2, the use of Flu-TBI was associated with a decreased risk of NRM (HR = 0.34, p = 0.009) but an increased risk of relapse (HR = 2.59, p = 0.01) without significant effect on survival and graft-versus-host disease. We conclude that for haplo-HCT recipients with ALL, Flu-TBI may be preferable for individuals at high risk of NRM while TBF should be considered in cases at high risk of relapse.

Role of allogeneic haematopoietic stem cell transplantation in the treatment of adult acute lymphoblastic leukaemia in the era of immunotherapy

ABSTRACT

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is currently the standard of care for adult acute lymphoblastic leukemia (ALL) patients. In recent years, with the continuous development of immunotherapy, such as chimeric antigen receptor T cells, blinatumomab, and inotuzumab ozogamicin, a series of vital clinical studies have confirmed its high response rate and favorable outcomes for ALL. Although the emergence of immunotherapy has expanded relapsed or refractory (r/r) ALL patients' opportunities to receive allo-HSCT, allo-HSCT is associated with potential challenges. In this review, the role of allo-HSCT in the treatment of adult ALL in the era of immunotherapy will be discussed.