Graft-versus-host disease (GVHD) can be a major cause of transplant-related mortality. However, a retrospective analysis showed that while more than half of the patients who received allogeneic hematopoietic stem-cell transplantation (HSCT) with posttransplant cyclophosphamide had GVHD, age was the only predictive factor for reduced progression-free survival (PFS) and overall survival (OS).
Supawee Saengboon, MD, of the MD Anderson Cancer Center in Houston, Texas, and colleagues conducted the research and presented their findings at the Tenth Annual Meeting of the Society of Hematologic Oncology.
“Allogeneic [HSCT] is curative for a large proportion of patients with high-risk hematologic malignancies,” Dr. Saengboon and colleagues wrote. “The introduction of posttransplant cyclophosphamide-based [GVHD] prophylaxis led to significant improvements in [haploidentical HSCT] outcomes and a remarkable increase in its use in the past decade.”
The researchers aimed to assess the long-term outcomes of 336 patients who underwent their first haploidentical HSCT between February 2009 and March 2019. Almost all patients (88%) received reduced intensity conditioning regimens. Most patients had acute myeloid leukemia/myelodysplastic syndrome (58.3%), while 16.3% had acute lymphocytic leukemia, 14.3% had a lymphoid malignancy, and 11% had myeloproliferative neoplasms.
The investigators defined long-term survivors as patients who were alive and disease free 2 years posttransplant. A third of patients (33.9%) were disease-free 2 years after HSCT. The median age of these patients was 45 years (range, 18-72 years). More than half the patients who were long-term survivors had GVHD, with 37.5% having acute GVHD of grade 2, 3, or 4 and 19% having chronic GVHD.
The 4-year PFS rate for all patients was 42%, while the 4-year OS rate was 47%. The 4-year PFS rate at a median follow-up of 52 months was 92% in patients who were long-term survivors, while the 4-year OS rate was 96%. Age ³55 years was the only factor predicting reduced PFS (hazard ratio [HR], 2.63; 95% CI, 1.01-6.84; P=.047) and OS (HR, 3.33; 95% CI, 1.08-12.23; P=.036) in a multivariate analysis.
The death rate was 9% in patients with long-term survival, with only 2 of those patients dying due to disease relapse. Secondary primary malignancy was the most common cause of nonrelapse mortality. A total of 2 patients died due to infection, 1 patient died due to GVHD, 1 died from sudden death, and 3 patients died from unknown causes.
“Our findings suggest an excellent long-term survival for patients who were disease-free at 2 years after [haploidentical HSCT]. Late relapses were low, and age was the only predictive factor for survival,” Dr. Saengboon and colleagues concluded.
Saengboon S, Ramdial J, Saini N, et al. Long-term outcomes after haploidentical stem cell transplantation (haplo-SCT) for hematologic malignancies. Oral Abstract AML-528. Presented at the Tenth Annual Meeting of the Society of Hematologic Oncology; September 28-October 1, 2022; Houston, TX.