Older Patients are Living Longer after Stem Cell Transplants for Some Leukemias, Study Shows

Improvements in medical care have reduced the rate of relapse in acute myeloid leukemia after transplants, helped people live longer, and reduced mortality from other causes, according to large set of data.

Older patients with acute myeloid leukemia (AML) who received stem cell transplants are living longer with fewer complications and relapses, indicating that transplants should be offered more readily to patients over 65 years of age, according to a study published in Clinical Cancer Research, a journal of the American Association for Cancer Research (AACR). 

Many patients over 65 have been considered too infirm to receive either the chemotherapy necessary before allogeneic hematopoietic stem cell transplant (allo-HCT), or the treatment itself, which is recommended when other treatments fail to control AML. The use of allo-HCT among older patients has been growing, however.  

“In tandem with the marked increase in elderly patients receiving allo-HCT, we observed an impressive improvement over time in leukemia-free and overall survival,” said Ali Bazarbachi, MD, PhD, senior author of the study and a professor at the American University of Beirut in Lebanon. “These data indicate that allo-HCT should no longer be optional but should be mandatory for elderly patients.” 

Improved supportive care, newer generation anti-infectious agents, and high-resolution human leukocyte antigen (HLA) typing, among other medical advances, have made allo-HCT a safer and more popular option for older patients with AML, which has a median age at diagnosis of 68, Dr. Bazarbachi explained.   

“Over time, significant progress in allo-HCT has decreased mortality and allowed for the delivery of allo-HCT to older patients,” Dr. Bazarbachi said. 

In the study, Dr. Bazarbachi and colleagues sought to examine how the outcomes of elderly patients after allo-HCT have changed over time, using data from a large transplant registry. 

“We hoped these large-scale, real-world data could serve as a benchmark for future studies in this setting,” Dr. Bazarbachi said. “Our study represents one of the largest analyses to date assessing trends over time and predictive factors for outcomes in elderly AML patients after allo-HCT.” 

Dr. Bazarbachi and colleagues analyzed a data set from the European Society for Blood and Marrow Transplantation, a working group of more than 600 transplant centers that report transplantation and follow-up data to a central registry. The data set consisted of 7,215 patients who received their first allo-HCT for AML at age 65 or older, between 2000 and 2021. At the time of their transplants, 64% of the patients were in their first complete AML remission, 14% were in their second complete AML remission, and 22% had active disease. 

The researchers assessed outcomes in the three years immediately following allo-HCT. They compared outcomes between patients treated from 2000 to 2009 (728 patients), 2010 to 2014 (1,775 patients), and 2015 to 2021 (4,712 patients). Relapse incidence decreased significantly from 37% to 31% to 30% across the three time periods; similarly, non-relapse mortality (death from anything other than AML) was 31% from 2000 to 2014 and decreased to 27% from 2015 to 2021. 

Both leukemia-free survival and overall survival steadily increased over time. Leukemia-free survival climbed from 32% to 38% to 44% across the three time periods, while overall survival climbed from 37% to 42% to 49%.  

The researchers also studied the incidence of graft-versus-host-disease (GvHD), a potentially serious condition in which donor cells recognize the patient’s body as foreign and attack healthy tissues. The incidence of chronic GvHD decreased from 35% between 2000 and 2014 to 31% between 2015 and 2021, and GvHD- and relapse-free survival rose from 22% to 29% to 34%. 

Improvements in all outcomes except non-relapse mortality were observed regardless of whether patients were in their first complete response, second complete response, or had active disease at the time of transplant. For patients with active disease, however, these differences were only significant in the most recent time period (2015 to 2021). Decreases in non-relapse mortality were only observed for patients experiencing their second complete response.