Comparing outcomes of donors for a second allogenic stem cell transplant for patients with acute lymphoblastic leukemia

This study aimed to compare outcomes of donor types for a second allogeneic stem cell transplant (alloSCT) in patients with relapsed acute lymphoblastic leukemia (ALL). 

This study concluded that there is no major difference in overall survival between a matched unrelated donor (MUD) and a half-matched donor (HMD) in these patients.  

Patients with ALL are often treated with an alloSCT. This is where cells from a donor are transplanted to a patient in order to replace healthy cells lost during cancer treatment and to boost the immune system. Donors are commonly siblings or other peopled that have similar tissue typing characteristics (HLA) as the patient. Matched unrelated donors (MUD) are very difficult to find. Transplants can also be done with half-match (haploidentical) donors (HMD) and are usually family members. 

If a patient relapses after a first alloSCT, a second alloSCT can be given. However, the optimal donor choice for a second alloSCT in patients with relapsed ALL is unknown. 

This study involved 165 patients with relapsed ALL after a first alloSCT. For their second alloSCT, 104 patients received a MUD transplant, while 61 had HMDs. The average follow-up for all patients was 27 months.

The average overall survival (OS) was 11.4 months for the MUD group compared to 15.6 months in the HMD group. The 2-year OS rate was 49% for the HMD group compared to 31% for the MUD group. However, this difference was not statistically significant. 

Relapse rate at 2 years was slightly more common in the MUD group (57%) compared to the HMD group (41%).

There was no difference in mortality not related to relapse and graft vs host disease (GVHD; a complication of alloSCT where the transplanted cells attack the patients) between groups.   

If patients had a longer time from the first alloSCT to relapse, this was associated with improved OS, leukemia free-survival (LFS) GVHD-free relapse-free survival, and a lower occurrence of relapse.

This study concluded that there was no major difference in survival between the MUD and HMD for a second alloSCT in patients with relapsed ALL.

This study was based on medical records. Information such as the status of minimal residual disease (the existence of cancer cells left before SCT) was missing. This might have affected the results.