According to the results of a study published in Clinical Cancer Research, survival of adult patients with relapsed Philadelphia (Ph)-positive acute lymphoblastic leukemia (ALL) following allogeneic hematopoietic cell transplantation (allo-HCT) steadily increased over the 20-year period between 2000 and 2019.
Relapse after allo-HCT remains the leading cause of transplant failure in patients with Ph-positive ALL. To evaluate changes over time in overall survival (OS) of patients with Ph-positive ALL following relapse, the researchers conducted a retrospective, registry-based, multicenter study.
They assessed patient characteristics, risk factors, and clinical outcomes among 899 adult patients with Ph-positive ALL who relapsed between 2000 and 2019 after allo-HCT performed in first complete remission at European Society for Blood and Marrow Transplantation participating centers. The median follow-up duration for surviving patients was 56 months.
For the 899 patients, the median age at transplant and at relapse was 44 and 45.4 years, respectively. Relapse occurred between 2000 and 2004 for 116 patients, between 2005 and 2009 for 225 patients, between 2010 and 2014 for 294 patients, and between 2015 and 2019 for 264 patients.
From 2000 to 2019, the investigators observed a progressive increase in patient age at transplant (from 40.6 to 46.1 years; P =.007), in the use of matched unrelated donors (from 34.5% to 56%; P =.0002), peripheral blood stem cells (from 60.3% to 84.5%; P <.0001), reduced intensity conditioning (from 16% to 34.5%; P =.004), and in vivo T-cell depletion (from 28% to 62%; P <.0001) and a progressive decrease in total body irradiation (from 73% to 53%; P =.0002).
The 2-year OS after relapse increased from 27.8% for patients who relapsed between 2000 and 2004 to 54.8% for those who relapsed between 2015 and 2019 (P =.001). Among patients who had a second allo-HCT within 2 years after relapse (13.9%), the 2-year OS was 35.9%. Multivariate analysis revealed that longer time from transplant to relapse (P =.006) and year of relapse (2009-2009 and 2015-2019, P <.0001 for both) positively affected OS after relapse.
Limitations of the study included the retrospective design and lack of information regarding minimal residual disease status prior to relapse, of detailed information on the treatment of posttransplant relapse, and on maintenance therapy following second remission.
“We observed a major progressive improvement in OS from posttransplant relapse for patients with [Ph-positive] ALL over the years, likely multifactorial including transplant-related factors, posttransplant salvage, and improvement in supportive care,” the authors concluded. “These large-scale real-world data can serve as a benchmark for future studies in this setting.”
Bazarbachi A, Labopin M, Aljurf M, et al. 20-Year steady increase in survival of adult patients with relapsed Philadelphia-positive acute lymphoblastic leukemia post allogeneic hematopoietic cell transplantation. Clin Cancer Res. Published online January 12, 2022. doi:10.1158/1078-0432.CCR-21-2675