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Allogeneic hematopoietic cell transplantation (HCT) offers the possibility of curative therapy for patients with myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), and acute myelogenous leukemia (AML). However, post-HCT relapse remains a major problem, particularly in patients with high-risk cytogenetics and in patients who cannot tolerate consolidation chemotherapy (eg, due to previous toxicity). We assessed the toxicity and efficacy of 10-day decitabine (Dec), fludarabine (Flu), and 2 Gy total body irradiation (TBI) as a new conditioning regimen for allogeneic HCT in patients with MDS, CMML, or AML. Thirty patients were enrolled, including 11 with MDS, 2 with CMML, and 17 with AML. Patients received 20 mg/m 2 /day Dec on days -11 to -2, 30 mg/m 2 /day Flu on days -4 to -2, and 2 Gy TBI on day -1, followed by infusion of a donor stem cell graft on day 0. Postgrafting immunosuppression consisted of cyclosporin A and mycophenolate mofetil. At a median follow-up of 443 days, the overall survival was 53%, relapse incidence was 27%, and nonrelapse mortality was 27%. The incidence of severe acute (grade III/IV) graft-versus-host disease (GVHD) was 27%, and that of (predominantly mild) chronic GVHD was 60%. Immunomonitoring studies revealed that specific CD8 + T cell responses against epigenetically silenced tumor-associated antigens (TAAs), including cancer-testis antigens (MAGE-A1/A2/A3 and PRAME) and RHAMM, occurred more frequently in patients who had received Dec/Flu/TBI conditioning (8 of 11 patients) compared with a control group of patients who had received only Flu/TBI conditioning (2 of 9 patients). In summary, Dec/Flu/TBI conditioning proved feasible and effective and enhanced the induction of TAA-reactive CD8 + T cell responses in vivo, which may contribute to disease control post-transplantation. [ABSTRACT FROM AUTHOR]

Highlights • 26 patients with overt hematological relapse after allo-HCT were evaluable. • DAC + DLI proved feasible and effective in relapse after allo-HCT. • Overall response rate 19% (CR/CRi (4/26); PR (1/26)), stable disease in 54% (14/26). • Median overall survival was 4.7 months. Abstract The combination of 5-azacytidine (AZA) with donor lymphocyte infusions (DLIs) can induce remissions in patients with relapsed myeloid malignancies after allo-HCT. As decitabine (DAC) is known to be effective also in AML/MDS with leukocytosis, we investigated the combination of DAC with DLIs for relapse after allo-HCT. Between 2006 and 2016, 26 patients (median age 59 years) with AML (n = 18), MDS (n = 6), or MPN (n = 2) and overt hematological relapse after allo-HCT were treated. Median duration from allo-HCT to relapse was 306 days (range, 76–4943). Eighteen patients received DAC + DLIs, 8 DAC-only (median number cycles of DAC: 2, range 1–13, median number of DLIs: 2, range 1–10). The incidence of acute and chronic GvHD in patients receiving DLI was 17% (3/18) and 6% (1/18), respectively. CR/CRi was achieved in 15% (4/26), PR in 4% (1/26), and stable disease in 58% (15/26) of patients. Eight patients received a second allo-HCT. Median overall survival was 4.7 months. Elevated PD-L1 protein expression in bone marrow cells was detected in 4/8 patients with >20% blast infiltration prior to DAC, without a clear association with response. In conclusion, the DAC + DLI regimen proved feasible and effective in relapsed myeloid malignancies after allo-HCT, with efficacy not restricted to patients with low leukemic burden. [ABSTRACT FROM AUTHOR]