Most patients who underwent haploidentical hematopoietic stem-cell transplantation (HSCT) with antithymocyte globulin and posttransplant cyclophosphamide as graft-versus-host disease (GVHD) prophylaxis did not develop extensive chronic GVHD, according to research presented at the Tenth Annual Meeting of the Society of Hematologic Oncology (SOHO).
Momen Nassani, MD, of the King Faisal Specialist Hospital & Research Center in Riyadh, Saudi Arabia, and colleagues conducted the study and presented its results at the SOHO meeting.
“[HSCT] from human leukocyte antigen (HLA)-haploidentical family members offers a potential cure for patients with hematological malignancies who lack an HLA-matched donor,” Dr. Nassani and colleagues wrote. “[Haploidentical] HSCT with posttransplant cyclophosphamide is associated with induced immune tolerance, rapid hematopoietic recovery, lower [GVHD], and lower non-relapse mortality. We noticed a high incidence of high-grade GVHD, so we added antithymocyte globulin to the [haploidentical] HSCT transplant platform.”
Dr. Nassani and colleagues retrospectively reviewed medical records for all patients who received haploidentical HSCT for hematologic malignancies and were treated with myeloablation, antithymocyte globulin, and posttransplant cyclophosphamide. The analysis included 53 patients, most of whom had acute myeloid leukemia (60%). The remaining 40% of patients had acute lymphocytic leukemia, chronic myeloid leukemia, myelodysplastic syndrome, acute promyelocytic leukemia, or blastic plasmacytoid dendritic cell neoplasm.
Most patients received cells harvested from bone marrow (71%), while 27% received peripheral blood stem-cell transplants, and 2% received both. Myeloablative conditioning with thiotepa, busulfan, and fludarabine was used for patients with myeloid malignancies, while fludarabine plus total body irradiation of 1000 cGy was used for patients with lymphoid malignancies. All patients received antithymocyte globulin 2 mg/kg and posttransplant cyclophosphamide.
Acute GVHD from stage 2 to stage 4 occurred in 33% of patients, while extensive chronic GVHD occurred in 17% of patients at a median follow-up of 15 months.
The 1-year overall survival (OS) rate was 73.4% (95% CI, 59.3- 83.3), and the 1-year relapse-free survival (RFS) rate was 70.3% (95% CI, 55.6- 80.9). Primary graft failure did not occur in any patients, but researchers reported secondary graft failure in 2 patients. Hemorrhagic cystitis occurred in 33.9% of patients, while 90.5% of patients developed cytomegalovirus reactivation.
“[Haploidentical] HSCT for hematological malignancies with myeloablative conditioning, [posttransplant cyclophosphamide], and [antithymocyte globulin] 2 mg/kg is feasible and associated with favorable OS and RFS,” Dr. Nassani and colleagues concluded. “The risk of GVHD, [veno-occlusive disease], and [graft failure] is comparable to other case series.”
Nassani M, Rasheed W, Altareb M, et al. Outcomes of hematological malignancy patients who underwent haploidentical SC transplant with ATG of 2 mg/kg based conditioning regimen. Poster CT-163. Presented at the Tenth Annual Meeting of the Society of Hematologic Oncology; September 28-October 1, 2022; Houston, TX.