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3550 Allogeneic Hematopoietic Cell Transplantation with Sequential-Based Conditioning in Refractory / Relapsed Acute Myeloid Leukemia: Experience from a Single Institution

Program: Oral and Poster Abstracts
Session: 721. Allogeneic Transplantation: Conditioning Regimens, Engraftment and Acute Toxicities: Poster II
Hematology Disease Topics & Pathways:
Acute Myeloid Malignancies, AML, Combination therapy, Diseases, Therapies, Myeloid Malignancies
Sunday, December 10, 2023, 6:00 PM-8:00 PM

Carles Tolosa-Ridao, MD1,2*, Paola Charry, MD2*, Maria Suarez-Lledo, MD, PhD3*, Daniel Esteban3*, Marina Díaz-Beyá, MD, PhD4*, Albert Cortés-Bullich, MD5*, Beatriz Merchán Muñoz, MD2*, Alexandra Martínez-Roca, MD5*, Maria Teresa Solano2*, Francesca Guijarro, MD6*, Sandra Castaño-Díez, MD4*, Carlos Jimenez-Vicente, MD2*, Meritxell Nomdedeu, MD2*, Joan Cid, MD, PhD2*, Miquel Lozano, MD, PhD7*, Alexandra Pedraza, MD2*, Laura Rosiñol, MD, PhD8*, Enric Carreras9*, Alvaro Urbano-Ispizua Sr., MD10, Francesc Fernández-Avilés, MD3*, Carmen Martinez, MD, PhD3*, Jordi Esteve, MD, PhD2, Montserrat Rovira, MD2* and Maria Queralt Salas2*

1Hematology Department, Hospital Universitari Mútua Terrassa, Terrassa, Spain
2Hematopoietic Cell Transplantation Unit, Hospital Clínic de Barcelona, ICHMO, Barcelona, Spain
3Hospital Clínic de Barcelona, Barcelona, Spain
4Hematology Department, Hospital Clínic Barcelona, Barcelona, Spain
5Hematology Department, Hospital Clinic de Barcelona, ICMHO, Barcelona, Spain
6Hematopathology Unit, Pathology Department, Hospital Clínic de Barcelona, Barcelona, Spain
7Hospital Clínic de Barcelona, ICHMO, Barcelona, Spain
8Hematopoietic Cell Transplantation Unit,, Hospital Clínic de Barcelona, IDIBAPS, Barcelona, Spain
9Josep Carreras Foundation & Leukemia Research Institute, Barcelona, Spain
10Department of Hematology. Hospital Clinic de Barcelona. IDIBAPS. Universidad de Barcelona., Barcelona, Spain


Despite improvements in the treatment and outcomes of patients with acute myeloid leukemia (AML), in nearly 10–20% of the cases, a morphological remission (CR) after administrating induction regimens is not achieved. In other cases, and despite initial CR, early disease relapse may occur, with only a minority of patients durably benefiting from salvage regimens. Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative strategy for patients with relapsed / refractory (R/R) AML. However, the prognostic of these patients after allo-HCT remains dismal, with reported survival rates ranging from 20% to 35% in different publications.

Allo-HCT using peripheral blood and sequential-based conditioning regimens has been the transplant platform used at our institution for R/R AML during the last decade. During the study period the use of post-transplant cyclophosphamide (PTCY) combined with tacrolimus (TK) has been implemented on this allo-HCT setting.

This study evaluates the results obtained from a single institution obtained from using sequential allo-HCT for patients with R/R AML, and the effectiveness of having implemented the use of PTCY in this type of transplant. Very few studies have evaluated the safety of including PTCY-based in sequential-based conditioning allo-HCTs.


This study includes the 21 patients with R/R AML who underwent allo-HCT with sequential-based conditioning regimens at our institution between 2011 and 2022. Retrospective data were collected during June 2023.

Sequential regimens combined fludarabine (150 mg/m2), cytarabine (2 g/m2 x 5 days), and idarubicin (12 mg/m2 x 3 days) chemotherapy with low doses of Bu (n=3), melphalan (n=17), or treosulfan (n=1). Six adults transplanted after November 2016 received PTCY (50mg/kg/24h) on day +3 and +4 followed by TK from day +5 to day +90 for GvHD prevention.


The main baseline characteristics of the study cohort and according to the GVHD prophylaxis are shown in Table 1. The median age was 53 years (range 31-68), 11 (52%) patients were males, and all patients had R/R AML after having received at least one line of induction chemotherapy with curative intent. Fourteen (66.7%) patients received grafts from HLA-matched donors, and 7 (33.3%) from 9/10 HLA mismatched unrelated donors (MMUD). Baseline characteristics between patients who received PTCY and those who did not were balanced, except for the proportion of allo-HCT performed from MMUD which was higher in the PTCY group (66.7% vs. 20.0% p=0.03).

Post-transplant results are shown in Table 2. All patients engrafted (100%). Patients who received PTCY experienced similar median of days to neutrophil engraftment (18 vs. 15 days, P=0.103) and a longer median of time to platelet engraftment (25 vs. 13 days, P=0.046). The day +100 cumulative incidences (CI) of grade II-IV and III-IV aGVHD, and 2-year CI of moderate/severe cGVHD were 33.3%, 0% and 0% for patients who received PTCY-TK, and 40% (p=0.823), 33% (p=0.118), and 40.4% (p=0.099) for those who did not.

During the first 2-years after allo-HCT, 8 (38%) out of 21 patients died and 7 (21%) relapsed. The main causes of death were relapse (n=4, 19%) and infection (n=2, 9.5%), and the 2-year OS, PFS, NRM and CIR were 61.5%, 51.9%, 14.3%, and 33.3%.

As shown in Table 2, patients who received PTCY had comparable rates of OS (2-y: 50.0% vs. 66.7%, p=0.903) and RFS (2-y: 50.0% vs. 53.3%, p=0.873) and those who did not. In addition, and although no patient who received PTCY died secondary to transplant-related toxicity (2-y 0 vs. 20%, p=0.254), a non-significant trend to higher cumulative incidence of relapse (2-y: 50.0% vs. 26.7%, p=0.282) was observed in this group of patients. Lastly, a non-significant trend to higher GRFS was documented in patients who received PTCY (2-y: 50.0% and 25.0%, p=0.266).


At our institution, 50% of the patients with R/R AML going thought allo-HCT performed using sequential-based conditioning regimens survived after two years. The implementation of PTCY as part of the GVHD prophylaxis results decreased rates clinically relevant GVHD and NRM, resulting on a trend to better GRFS. Although the results provided by this analysis suggest that using PTCY in this allo-HCT is safe and effective, caution is still recommended considering the trend to higher relapse rates observed among these patients and the limited sample size.

Disclosures: Díaz-Beyá: Bristol Myers Squibb: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Jazz Pharma: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Martínez-Roca: BMS: Honoraria, Other: travel grants; Abbvie: Honoraria, Other: travel grants; Gilead: Other: Travel grants; Janssen: Other: travel grants; Takeda: Honoraria, Other: travel grants; Roche: Honoraria, Other: travel grants; Kite: Honoraria, Other: travel grants. Jimenez-Vicente: Pfizer: Other: Travel Grants; Abbvie: Other: Speaker, Travel Grants. Rosiñol: Janssen: Other: Honoraria for lectures; Sanofi: Other: Honoraria for lectures; Amgen: Other: Honoraria for lectures; Bristol Myers Squibb/Celgene: Other: Honoraria for lectures; Takeda: Other: Honoraria for lectures; GlaxoSmithKline: Other: Honoraria for lectures. Esteve: Gilead: Consultancy; Pfizer: Research Funding; Abbvie: Consultancy; Jazz Pharmaceuticals: Consultancy, Research Funding; Kronos Bio: Research Funding; Astellas: Consultancy.

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