FLAMSA reduced-intensity conditioning is equally effective in AML patients with primary induction failure as well as in first or second complete remission

Smart Conditioning with Venetoclax-Enhanced Sequential FLAMSA + RIC in Patients with High-Risk Myeloid Malignancies

Up to 50% of patients with high-risk myeloid malignancies die of relapse after allogeneic stem cell transplantation. Current sequential conditioning regimens like the FLAMSA protocol combine intensive induction therapy with TBI or alkylators. Venetoclax has synergistic effects to chemotherapy. In a retrospective survey among German transplant centers, we identified 61 patients with myeloid malignancies that had received FLAMSA-based sequential conditioning with venetoclax between 2018 and 2022 as an individualized treatment approach. Sixty patients (98%) had active disease at transplant and 74% had genetic high-risk features. Patients received allografts from matched unrelated, matched related, or mismatched donors. Tumor lysis syndrome occurred in two patients but no significant non-hematologic toxicity related to venetoclax was observed. On day +30, 55 patients (90%) were in complete remission. Acute GvHD II°-IV° occurred in 17 (28%) and moderate/severe chronic GvHD in 7 patients (12%). Event-free survival and overall survival were 64% and 80% at 1 year as well as 57% and 75% at 2 years, respectively. The off-label combination of sequential FLAMSA-RIC with venetoclax appears to be safe and highly effective. To further validate these insights and enhance the idea of smart conditioning, a controlled prospective clinical trial was initiated in July 2023.

Conditioning with fludarabine and treosulfan compared to FLAMSA-RIC in allogeneic stem cell transplantation for myeloid malignancies: a retrospective single-center analysis

Reduced intensity conditioning (RIC) and reduced toxicity conditioning (RTC) regimens enable allogeneic hematopoietic stem cell transplantation (alloSCT) to more patients due to reduction in transplant-related mortality (TRM). The conditioning regimens with fludarabine and treosulfan (Flu/Treo) or fludarabine, amsacrine, cytarabine (FLAMSA)-RIC have shown their efficacy and tolerability in various malignancies. So far, no prospective study comparing the two regimens is available. Two studies compared the regimens retrospectively, in which both provided similar outcome. In this retrospective, single-center analysis, these two regimens were compared with regard to outcome, rate of acute and chronic graft versus host disease (GvHD), and engraftment. 113 consecutive patients with myeloid malignancies who received Flu/Treo or FLAMSA-RIC conditioning prior to alloSCT between 2007 and 2019 were included. Except for age, previous therapies, and remission status before alloSCT, patient characteristics were well balanced. The median follow-up time within this analysis was 44 months. There was no significant difference in absolute neutrophil count (ANC) or platelet engraftment between the two conditioning regimens. Overall survival (OS), the relapse-free survival (RFS), and the TRM were not significantly different between the two cohorts. The rate of GvHD did not differ between the two groups. In summary, this retrospective analysis shows that there is no major difference regarding tolerability and survival between the Flu/Treo and FLAMSA-RIC regimens. Despite several limitations due to uneven distribution concerning age and remission status, we demonstrate that Flu/Treo and FLAMSA-RIC provide similar outcomes and are feasible in older and intensively pre-treated patients.

FLAMSA-RIC for Stem Cell Transplantation in Patients with Acute Myeloid Leukemia and Myelodysplastic Syndromes: A Systematic Review and Meta-Analysis

Reduced-intensity conditioning (RIC) regimens are established options for hematopoietic stem cell transplantation (HSCT) for patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). However, the efficacy of RIC regimens for patients with high-risk disease is limited. The addition of a fludarabine, amsacrine, and cytarabine (FLAMSA)-sequential conditioning regimen was introduced for patients with high-risk MDS and AML to combine a high anti-leukemic activity with the advantages of RIC. The current systematic literature review and meta-analysis was conducted with the aim of identifying all cohort studies of patients with AML and/or MDS who received FLAMSA-RIC to determine its efficacy and toxicity. Out of 3044 retrieved articles, 12 published studies with 2395 overall patients (18.1–76.0 years; 96.8% AML and 3.2% MDS; follow-up duration of 0.7–145 months; 50.3% had active AML disease before HSCT) met the eligibility criteria and were included in the meta-analysis. In the pooled analysis, the 1- and 3-year overall survival (OS) rates were 59.6% (95% confidence interval (CI), 47.9–70.2%) and 40.2% (95% CI, 28.0–53.7%), respectively. The pooled 3-year OS rate of the patients who achieved CR1 or CR2 prior to HSCT was 60.1% (95% CI, 55.1–64.8%) and the percentage of those with relapse or refractory disease was 27.8% (95% CI, 23.3–32.8%). The pooled 3-year leukemia-free survival (LFS) rate was 39.3% (95% CI, 26.4–53.9%). Approximately 29% of the patients suffered from grades 2–4 acute graft-versus-host disease (GVHD), while 35.6% had chronic GVHD. The pooled 1- and 3-year non-relapse mortality (NRM) rates were 17.9% (95% CI, 16.1–19.8%) and 21.1% (95% CI, 18.8–23.7%), respectively. Our data indicates that the FLAMSA-RIC regimen is an effective and well-tolerated regimen for HSCT in patients with high-risk AML and MDS.

Allogeneic haemopoietic transplantation for acute myeloid leukaemia in second complete remission: a registry report by the Acute Leukaemia Working Party of the EBMT

Allogeneic haemopoietic cell transplant (allo-HCT) may be curative in acute myeloid leukaemia (AML) in second complete remission (CR2) but the impact of reduced intensity (RIC) versus myeloablative conditioning (MAC) is uncertain. The Acute Leukaemia Working Party of the European Society for Blood and Bone Marrow Transplantation Registry studied an AML CR2 cohort characterised by age ≥ 18 years, first allo-HCT 2007-2016, available cytogenetic profile at diagnosis, donors who were matched family, volunteer unrelated with HLA antigen match 10/10 or 9/10 or haplo-identical. The 1879 eligible patients included 1010 (54%) MAC allo-HCT recipients. In patients <50 years (y), two year outcomes for MAC vs RIC allo-HCT were equivalent with leukaemia-free survival (LFS) 54% for each, overall survival (OS), 61% vs 62%, non-relapse mortality (NRM) 18% vs 15% and graft versus host disease relapse-free survival (GRFS) 38% vs 42%. In patients ≥50 y, 2 y outcomes for MAC vs RIC allo-HCT were equivalent for LFS 52% vs 49%, OS 58% vs 55% and GRFS 42.4% vs 36%. However, NRM was significantly inferior after MAC allo-HCT, 27% vs 19% (P = 0.01) despite worse cGVHD after RIC-allo (32% vs 39%). These data support the need for ongoing prospective study of conditioning intensity and GVHD mitigation in AML.

Efficacy and Safety of Unmanipulated Haploidentical Related Donor Allogeneic Peripheral Blood Stem Cell Transplantation in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Background:

Studies of haploidentical-related donor (HRD) stem cell transplantation using a combination of peripheral blood stem cells (PBSCs) and bone marrow as the graft have reported encouraging results for patients with hematological diseases. However, few studies specifically reported transplantation of only PBSCs from HRDs among patients with relapsed or refractory acute myeloid leukemia (AML). Here, the long-term outcomes and side effects of unmanipulated HRD PBSC transplantation (HRD-PBSCT) for relapsed/refractory AML were analyzed.

Methods:

We performed a retrospective analysis of the outcomes in relapsed/refractory AML patients who underwent PBSCT from HRDs (n = 36).

Results:

Thirty-one (86.1%) patients in the HRD-PBSCT group achieved platelet recovery. The cumulative incidence of acute graft-versus-host disease (aGVHD) in the HRD-PBSCT group was 40.00%, and the cumulative incidence of grades 2–4 aGVHD in this group was 13.33%. A total of 13 patients in the HRD-PBSCT group had recurrent disease at a median of 183 days after transplantation (range: 10–1700 days), reaching cumulative incidences of relapse of 50.28% at 5 years. On multivariate analysis, donor age and patient age >40 years were independent risk factors for inferior disease-free survival or overall survival (P < 0.05). The results of the present study demonstrate rapid and complete neutrophil engraftment, a low incidence of grade 2–4 aGVHD, and promising survival rates in patients after HRD-PBSCT. Thus, granulocyte colony-stimulating factor–primed PBSCs may be a reliable graft source in unmanipulated HRD-HSCT under myeloablative conditioning when no matched sibling donor is available.

Conclusions:

Our results support the feasibility, effectiveness, and tolerability of PBSCs as a graft source in unmanipulated HRD transplantation under myeloablative conditioning in patients with leukemia.

Sequential treatment combining cladribine-based re-induction, myeloablative allogeneic HSCT, and prophylactic donor lymphocyte infusion: a promising treatment for refractory acute myeloid leukemia

We describe the first multicenter prospective study to assess the efficacy, safety, and immune reconstitution of a novel sequential transplant approach in 24 patients with primary induction failure/relapsed acute myeloid leukemia (AML). The sequential regimen consisted of cladribine 5 mg/m²/day and cytarabine 2 g/m²/day for 5 days and mitoxantrone 7 mg/m²/day for 3 days, followed by myeloablative allogeneic hematopoietic stem cell transplantation (allo-HSCT) using intravenous busulfan (3.2 mg/kg/day) for 4 days and cyclophosphamide (60 mg/kg/day) for 2 days. Patients in CR without acute graft-versus-host disease at day + 90 received prophylactic donor lymphocyte infusion (pDLI). At the time of transplantation, a marrow blast infiltration > 20% or any level of circulating blasts was found in 62.5% of patients. The cumulative incidence of relapse at 2 years was 29.8%. Overall survival (OS) was 74.5% at 1 year and 56.5% at 2 years. Leukemia-free survival (LFS) at 1 and 2 years was 62.5 and 50.5%, respectively. Multivariate analysis demonstrated that haploidentical related donor, pDLI, and experiencing chronic graft-versus-host disease (cGVHD) were protective from relapse. Total T cells and T cell subsets in peripheral blood recovered at 3 months post-HSCT. The expressions of immune checkpoints (cytotoxic T lymphocyte antigen 4 and programmed death 1) were extremely low in T cells over the first 1 year post-transplantation.

Similar outcome of allogeneic stem cell transplantation after myeloablative and sequential conditioning regimen in patients with refractory or relapsed acute myeloid leukemia: A study from the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire

Patients with acute myeloid leukemia (AML) in relapse or refractory to induction therapy have a dismal prognosis. Allogeneic hematopoietic stem cell transplantation is the only curative option. In these patients, we aimed to compare the results of a myeloablative transplant versus a sequential approach consisting in a cytoreductive chemotherapy followed by a reduced intensity conditioning regimen and prophylactic donor lymphocytes infusions. We retrospectively analyzed 99 patients aged 18-50 years, transplanted for a refractory (52%) or a relapsed AML not in remission (48%). Fifty-eight patients received a sequential approach and 41 patients a myeloablative conditioning regimen. Only 6 patients received prophylactic donor lymphocytes infusions. With a median follow-up of 48 months, 2-year overall survival was 39%, 95% confidence interval (CI) (24-53) in the myeloablative group versus 33%, 95% CI (21-45) in the sequential groups (P = .39), and 2-year cumulative incidence of relapse (CIR) was 57% versus 50% respectively (P = .99). Nonrelapse mortality was not higher in the myeloablative group (17% versus 15%, P = .44). In multivariate analysis, overall survival, CIR and nonrelapse mortality remained similar between the two groups. However, in multivariate analysis, sequential conditioning led to fewer acute grade II-IV graft versus host disease (GVHD) (HR for sequential approach = 0.37; 95% CI: 0.21-0.65; P < .001) without a significant impact on chronic GVHD (all grades and extensive). In young patients with refractory or relapsed AML, myeloablative transplant and sequential approach offer similar outcomes except for a lower incidence of acute GvHD after a sequential transplant.

Treatment of relapsed/refractory acute myeloid leukaemia in adults

The prognosis of relapsed acute myeloid leukaemia (AML) is poor and treatment is challenging. While the most potent treatment modality for patients who achieve a complete remission after relapse is still allogeneic haematopoietic cell transplantation (allo-HCT), both transplant-related mortality and relapse rates are high and many patients are not candidates for this approach. After a few decades of relative stasis in this field, a large number of novel approaches have become available to tackle this highly fatal disease. This is mostly due to our improved understanding of disease pathogenesis (including targetable mutations) and the anti-leukaemia potential of the immune system. Several small-molecule inhibitors and immunotherapeutic options are being explored in clinical trials and many more are in pre-clinical phase. Future studies will focus on novel and mechanistically driven combinations, sequential treatments, and low-toxicity maintenance strategies. While cure of relapsed/refractory AML without allo-HCT is currently unlikely, treatments are becoming less toxic and remissions are lasting longer.

Salvage therapy for acute chemorefractory leukemia by allogeneic stem cell transplantation: the Korean experience

Little is known about the characteristics that make patients with acute leukemia suitable for undergoing salvage therapy by allogeneic hematopoietic stem cell transplantation (allo-HSCT). Here, we analyzed the clinical outcomes of 223 patients with acute leukemia who underwent allo-HSCT while not in complete remission (CR). The primary end points were overall survival (OS) and CR rate. CR was achieved in 79.8% of patients after allo-HSCT. Acute graft-versus-host disease (GVHD) was significantly associated with CR (P = 0.045). During a median follow-up of 30.1 months, the median OS was 6.1 months. OS was significantly longer in patients with good or standard risk cytogenetic characteristics than in those with poor risk cytogenetic characteristics (P = 0.029, P = 0.030, respectively). Patients who received allo-HSCT from a matched sibling donor had better survival than those with unrelated donors (P = 0.015). Primary chemorefractoriness was not associated with poor survival (P = 0.071). The number of chemotherapies before allo-HSCT was significantly correlated with outcome (P = 0.006). Chronic GVHD was a strong predictor of a longer OS (P = 0.025). In conclusion, survival of patients with primary chemorefractory acute leukemia is not lower when treated upfront with allo-HSCT. Hence, allo-HSCT should be actively considered in such patients. Acute and chronic GVHD is associated with better outcomes patients with acute leukemia who have undergone allo-HSCT and not achieved CR.

Diagnosis and management of AML in adults: 2017 ELN recommendations from an international expert panel

The first edition of the European LeukemiaNet (ELN) recommendations for diagnosis and management of acute myeloid leukemia (AML) in adults, published in 2010, has found broad acceptance by physicians and investigators caring for patients with AML. Recent advances, for example, in the discovery of the genomic landscape of the disease, in the development of assays for genetic testing and for detecting minimal residual disease (MRD), as well as in the development of novel antileukemic agents, prompted an international panel to provide updated evidence- and expert opinion-based recommendations. The recommendations include a revised version of the ELN genetic categories, a proposal for a response category based on MRD status, and criteria for progressive disease.