While nearly half of patients receiving fractionated total body irradiation plus fludarabine as a conditioning regimen had acute graft-versus-host disease (GVHD) 100 days after a mismatched transplant, most patients did not have extensive chronic GVHD 2 years after transplant, according to a recent study.
The researchers investigated the use of this conditioning regimen in patients undergoing mismatched related or unrelated donor hematopoietic stem-cell transplantation (HSCT) with posttransplant cyclophosphamide as GVHD prophylaxis. Most patients had acute lymphoblastic leukemia (46.5%) or acute myeloid leukemia (36.1%).
Amrita Desai, MD, MPH, of the City of Hope in Duarte, California, and colleagues conducted the research and presented their findings at the Tenth Annual Meeting of the Society of Hematologic Oncology.
The retrospective single-center study included 155 patients with hematologic malignancies who received a radiation dose of 1200 cGy with fludarabine and posttransplant cyclophosphamide 50 mg/kg on posttransplant days 3 and 4, mycophenolate mofetil on days 5 to 35, and tacrolimus or sirolimus starting on day 5.
The median patient age was 38 years (range, 9-60 years), and most patients were male (56.8%). The median donor age was 31 years old, with 67.1% being haploidentical donors and 32.9% being mismatched-unrelated donors. Nearly all patients (97.5%) had a Karnofsky score for performance status of ³80.
At day 100, 44.2% of patients had acute GVHD grade 2-4, while 5.8% had acute GVHD grade 3-4. Nearly half (47.7%) of patients had chronic GVHD of any grade at 2 years, while 35.6% had extensive chronic GVHD at 2 years.
The 2-year overall survival rate was 80.1%, with a disease-free survival rate of 76.9% at a median follow-up of 24 months (range, 3-81 months). The 100-day nonrelapse mortality rate was 1.9%, while the 2-year relapse rate was 11.8%.
The fractionated total body irradiation plus fludarabine conditioning regimen “needs to be studied in future prospective randomized trials” but was a “well-tolerated [myeloablative conditioning] regimen in mismatched donors with leukemia and [myelodysplastic syndrome] with low transplant-related mortality and good outcomes,” Dr. Desai and colleagues concluded.
Desai A, Yang D, Blackmon A, et al. Fractionated total body irradiation and fludarabine based conditioning regimen with post-transplant cyclophosphamide (PTCy) for mismatched related and unrelated donors HCT for acute leukemia and MDS. Poster CT-505. Presented at the Tenth Annual Meeting of the Society of Hematologic Oncology; September 28-October 1, 2022; Houston, TX.