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3692 Comparison of Myeloablative Versus Reduced-Intensity Fludarabine/Busulfan Regimen in Patients with Myelodysplastic Syndrome Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Program: Oral and Poster Abstracts
Session: 637. Myelodysplastic Syndromes — Clinical and Epidemiological: Poster III
Hematology Disease Topics & Pathways:
Workforce, Health Outcomes Research, GVHD, Diseases, Immune Disorders, Myeloid Malignancies
Monday, December 13, 2021, 6:00 PM-8:00 PM

Shuhei Kurosawa1*, Yoshimitsu Shimomura2*, Hidehiro Itonaga, MD, PhD3*, Yuho Najima4, Takeshi Kobayashi4, Yukiyasu Ozawa5*, Yoshinobu Kanda6, Shinichi Kako7, Toshiro Kawakita8*, Ken-Ichi Matsuoka9, Yumiko Maruyama10*, Shuichi Ota11, Hideyuki Nakazawa12*, Kazunori Imada13*, Takafumi Kimura14*, Junya Kanda15, Takahiro Fukuda16*, Yoshiko Atsuta, MD, PhD17,18* and Ken Ishiyama19

1Division of Stem Cell and Molecular Medicine, Center for Stem Cell Biology and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
2Department of Haematology, Kobe City Hospital Organization Kobe City Medical Centre General Hospital, Kobe, Japan
3Department of Hematology, Nagasaki University Hospital, Nagasaki, Japan
4Hematology Division, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, Japan
5Department of Hematology, Japanese Red Cross Nagoya First Hospital, Nagoya, Japan
6Division of Hematology, Jichi Medical University, Shimotsuke, Japan
7Division of Hematology, Jichi Medical University Saitama Medical Center, Saitama, Japan
8Department of Hematology, National Hospital Organization Kumamoto Medical Center, Kumamoto, Japan
9Department of Hematology and Oncology, Okayama University Hospital, Okayama, Japan
10Department of Hematology, University of Tsukuba Hospital, Tsukuba, Japan
11Department of Hematology, Sapporo Hokuyu Hospital, Sapporo, Japan
12Department of Hematology, Shinshu University School of Medicine, Matsumoto, Japan
13Department of Hematology, Japanese Red Cross Osaka Hospital, Osaka, Japan
14Preparation Department, Japanese Red Cross Kinki Block Blood Center, Ibaraki, Japan
15Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
16Hematopoietic Stem Cell Transplantation Division, National Cancer Center Hospital, Tokyo, Japan
17Japanese Data Center for Hematopoietic Cell Transplantation, Nagoya, Japan
18Department of Registry Science for Transplant and Cellular Therapy, Aichi Medical University School of Medicine, Nagakute, Japan
19Department of Hematology, Kanazawa University Hospital, Kanazawa, Japan


Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment for myelodysplastic syndrome (MDS) but is associated with high non-relapse mortality (NRM). Its use was originally limited to younger patients eligible for myeloablative conditioning (MAC). Introducing reduced-intensity conditioning (RIC), such as a combination of fludarabine with reduced doses of busulfan (Flu/Bu2), increased the number of elderly patients suitable for allo-HSCT. Additionally, a combination of fludarabine and myeloablative doses of busulfan (Flu/Bu4) was developed to retain the antitumor activity of MAC and reduce the NRM to the level of RIC. However, few published reports have compared Flu/Bu4 and Flu/Bu2 in patients with MDS. We thus retrospectively performed a nationwide study to compare the outcomes of Flu/Bu4 and Flu/Bu2 in MDS patients undergoing allo-HSCT.


Clinical data were obtained from the Japanese Data Center for Hematopoietic Cell Transplantation. Inclusion criteria were age ≥16 years, diagnosis of de novo MDS, first allo-HSCT between 2006 and 2018, and receiving Flu/Bu4 consisted of intravenous busulfan (12.8 mg/kg) and fludarabine (125–180 mg/m2) or Flu/Bu2 consisted of intravenous busulfan (6.4 mg/kg) and the same dose of fludarabine. Administration of anti-thymocyte globulin and low-dose total body irradiation (TBI, total dose ≤4 Gy) was permitted. Propensity score (PS)-matched analysis was performed to minimize selection bias, and the PS was calculated by logistic regression using the following factors: age, sex, hematopoietic cell transplantation-comorbidity index, French-American-British classification at diagnosis, cytogenetic risk, International Prognostic Scoring System score at diagnosis, disease status at allo-HSCT, bone marrow (BM) blasts at allo-HSCT, days from diagnosis to allo-HSCT, stem cell source, graft-versus-host disease (GVHD) prophylaxis, administration of anti-thymocyte globulin and TBI, and year of allo-HSCT. PS matching was performed at a 1:1 ratio using the nearest neighbor-matching method; caliper width was fixed at 0.2. The primary endpoint was the 3-year overall survival (OS).


In total, 3406 patients underwent their first allo-HSCT: 447 and 256 received Flu/Bu4 and Flu/Bu2, respectively. Among them, 202 patients were assigned to each of the Flu/Bu4 and Flu/Bu2 groups after PS matching. The PS model created comparable cohorts with balanced baseline characteristics. The median age was 61 (range, 21-75) years. At the time of allo-HSCT, BM blasts were ≥5% in 273 (67.6%) patients. Regarding stem cell source, BM, peripheral blood stem cell, and cord blood was used in 268 (66.3%), 51 (12.6%), and 85 (21.0%) patients, respectively. The median follow-up period for survivors was 1117 (range, 40–3784) days.

The 3-year OS rates were 44.8% (95% confidence interval [CI], 37.1–52.1%) and 46.9% (95% CI, 39.2–54.2%) in the Flu/Bu4 and Flu/Bu2 groups, respectively (P = 0.671, Figure 1A). The 3-year GVHD- and relapse-free survival rates were 28.8% (95% CI, 22.2–35.7%) and 33.0% (95% CI, 26.2–40.0%; P = 0.357, Figure 1B); the 3-year cumulative incidence of relapse, 28.9% (95% CI, 22.6–35.6%) and 30.0% (95% CI, 23.6–36.6%; P = 0.471, Figure 1C); and the 3-year cumulative incidence of NRM, 28.2% (95% CI, 21.7–35.0%) and 27.1% (95% CI, 20.6–33.9%; P = 0.597, Figure 1D) in the Flu/Bu4 and Flu/Bu2 groups, respectively. The 100-day cumulative incidence of grade II–IV acute GVHD was significantly higher in the Flu/Bu4 group than in the Flu/Bu2 group (41.7% [95% CI, 34.8–48.4%] vs. 29.3% [95% CI, 23.2–35.7%], P = 0.012, Figure 1E). The 100-day cumulative incidences of grade III–IV acute GVHD were 11.4% (95% CI, 7.5–16.3%) and 6.5% (95% CI, 3.6–10.5%; P = 0.064), while the 1-year cumulative incidences of extensive chronic GVHD were 19.5% (95% CI, 14.2–25.4%) and 15.1% in the Flu/Bu4 and Flu/Bu2 groups, respectively (95% CI, 10.5–20.6%; P = 0.196, Figure 1F). According to the findings of subgroup analyses, no patient had a favorable OS when using either of the two regimens (Figure 2).


The OS did not significantly differ between the Flu/Bu4 and Flu/Bu2 groups. While the Flu/Bu4 group was at an increased risk of acute GVHD, the relapse was not significantly different between the two groups. Data from more patients are needed to determine the optimal intensity of conditioning regimens in patients with MDS.

Disclosures: Kanda: Sanofi: Research Funding; MSD: Honoraria; Otsuka Pharmaceutical: Honoraria, Research Funding. Kako: Novartis Pharma K.K.: Honoraria; Nippon Shinyaku Co., Ltd.: Honoraria; Sanofi K.K.: Honoraria; Bristol-Myers Squibb/Celgene K.K.: Honoraria; Meiji Seika Pharma Co., Ltd.: Honoraria; Kyowa Hakko Kirin Co., Ltd.: Honoraria; Pfizer Japan Inc.: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Janssen Pharmaceutical K.K.: Honoraria; Fuji Pharma Co., Ltd.: Honoraria; CSL Behring K.K.: Honoraria; Amgen K.K.: Honoraria; Takeda Pharmaceutical Co., Ltd.: Honoraria. Imada: Novartis Pharma K.K.: Honoraria; Takeda Pharmaceutical Co. Ltd.: Honoraria; Otsuka Pharmaceutical Co. Ltd.: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Astellas Pharma Inc.: Honoraria; Bristol-Myers Squibb K.K.: Honoraria; Celgene Co., Ltd.: Honoraria. Kanda: Astellas Pharma Inc.: Consultancy, Honoraria; Bristol-Myers Squibb Co: Honoraria; CHUGAI PHARMACEUTICAL Co., Ltd.: Honoraria; DAIICHI SANKYO Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Eisai: Research Funding; Janssen Pharmaceutical K.K.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kyowa Kirin Co., Ltd.: Honoraria; Megakaryon Co: Honoraria, Membership on an entity's Board of Directors or advisory committees; NextGeM Inc: Patents & Royalties; Novartis Pharma K.K.: Honoraria; Ono Pharma Inc.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Sanofi K.K.: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; SymBio Pharmaceuticals, Ltd.: Membership on an entity's Board of Directors or advisory committees; Takeda Pharmaceutical Company Limited: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen Astellas BioPharma: Honoraria; TEIJIN PHARMA LIMITED.: Honoraria. Atsuta: Astellas Pharma Inc.: Speakers Bureau; Mochida Pharmaceutical Co., Ltd.: Speakers Bureau; Meiji Seika Pharma Co, Ltd.: Honoraria; AbbVie GK: Speakers Bureau; Kyowa Kirin Co., Ltd: Honoraria.

*signifies non-member of ASH