Is there a stronger graft-versus-leukemia effect using HLA-haploidentical donors compared with HLA-identical...

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Haploidentical hematopoietic stem cell transplants (HSCT) are increasingly utilized.
• The graft-versus-leukemia (GVL) effect of haploidentical HSCT compared to matched sibling donor (MSD) HSCT is not well understood.

Purpose of the Study:

• To compare the GVL effect and overall outcomes of haploidentical HSCT versus MSD HSCT in acute leukemia patients.
• To identify factors influencing relapse after T-cell-replete grafts.

Main Methods:

• Analysis of 10,679 acute leukemia patients undergoing HSCT from MSD (n=9815) or haploidentical donors (n=864) between 2007-2012.
• Cox regression modeling incorporating acute and chronic graft-versus-host disease (GVHD) as time-dependent variables.

Main Results:

• No significant difference in relapse probability between haploidentical and MSD grafts, suggesting a similar GVL effect.
• Higher non-relapse mortality in the haploidentical group compared to MSD group (P<10(-5)).
• Leukemia-free survival was superior in MSD patients (P<10(-5} for T-cell-replete, P=0.0006 for T-cell-depleted).

Conclusions:

• Haploidentical HSCT offers a comparable GVL effect to MSD HSCT in acute leukemia.
• Increased non-relapse mortality and lower leukemia-free survival are associated with haploidentical HSCT.
• Remission status, Karnofsky score, and GVHD severity are critical factors for relapse risk.