CT-163 Outcomes of Hematological Malignancy Patients Who Underwent Haploidentical SC Transplant With ATG of 2 Mg/kg Based Conditioning Regimen

Introduction: Hematopoietic stem cell transplantation from human leukocyte antigen (HLA)-haploidentical family members (Haplo-HSCT) offers a potential cure for patients with hematological malignancies who lack an HLA-matched donor. Haplo-HSCT with post-transplant cyclophosphamide (PTCY) is associated with induced immune tolerance, rapid hematopoietic recovery, lower graft-versus-host disease (GVHD), and lower non-relapse mortality (NRM). We noticed a high incidence of high-grade GVHD, so we added antithymocyte globulin (ATG) to the Haplo-HSCT transplant platform. Here we review the outcomes of patients who received PTCY and ATG 2 mg/kg (ATG-2). Methods: We retrospectively reviewed the medical records of all patients who underwent Haplo-HSCT for malignant hematologic disorders, using myeloablation, ATG-2, and PTCY for GVHD prophylaxis. We analyzed the patient's characteristics and outcomes of the transplant. We used the Kaplan-Meier method to estimate survival probabilities. Statistical analysis was performed with EasyMedStat. Results: Fifty-three-patients were reviewed, 26 (49.1%) males and 27 (50.9%) Females. The majority of patients had AML (60%). Other diagnoses included ALL, CML, MDS, APL, and BPDCN. Seventy-one percent of patients received bone marrow harvested cells and 27% received PBSCT and 2% received both BM and PBSCT. The conditioning was myeloablative in the form of Thiotepa/Busulfan/Fludarabine (73.5%) for myeloid malignancies and Fludarabine/TBI 1000 cGy (26.4%) for lymphoid malignancies. The median duration of follow-up was 15 months. At 12 months, the overall survival (OS) was 73.4% (95% CI: 59.3-83.3), and the relapse-free survival (RFS) was 70.3% (95% CI: 55.6-80.9). 33% of patients developed GII to IV acute GVHD and 17% of patients developed extensive chronic GVHD. There were no cases of primary graft failure (GF), but two patients developed secondary GF. One-third of patients developed hemorrhagic cystitis (33.9%) and the majority of patients (90.5%) developed CMV reactivation. Only two patients developed Veno-occlusive disease (VOD). Conclusions: Haplo-HSCT for hematological malignancies with myeloablative conditioning, PTCY and ATG 2 mg/kg is feasible and associated with favorable OS, and RFS. The risk of GVHD, VOD, and GF is comparable to other case series.