P068 : ALLOGENEIC HEMATOPOIETIC CELL TRANSPLANTATIONS WITH KILLER IMMUNOGLOBULIN-LIKE RECEPTOR GENOTYPE MATCHED DONORS HAVE REDUCED INCIDENCE OF GRAFT VERSUS HOST DISEASE WITH NO EFFECT ON THE RISK OF DISEASE RELAPSE

Abstract

Background Complications of allogeneic hematopoietic cell transplantation (HCT), primarily graft versus host disease (GVHD) and relapse of the underlying disease are substantial. In spite of high resolution HLA matching incidences of clinically significant GVHD and disease relapse among Albertan HCT recipients remain as high as 35% and 20%, respectively. Unfortunately, strategies/treatments aiming to control GVHD in most cases lead to increase in the rate of disease relapse and infections. In the recent years, the natural killer (NK) cell genetic system, regulated by the activating and inhibitory Killer Immunoglobulin-like Receptors (KIR) has garnered substantial research interest as a modifier of HCT outcomes. Here we set out to determine the influence of KIR matching between HCT donor and recipient pairs on allogeneic HCT complications. Study design KIR gene repertoires of 200 allo-HCT pairs were obtained by a Luminex-based rSSO method. Donor (D) and recipients (R) were ‘matched’ for KIR genotypes when both carried either AA (two copies of group A haplotypes) or B/x (at least one copy of group B haplotype) genotypes. Effect of KIR matching on significant GVHD (described as grade 2–4 acute GVHD or chronic GVHD needing systemic therapy) as well as disease relapse was analyzed using competing-risks regression and Cox proportional hazard statistics. Results A significant protection against GVHD was conferred upon when both the donor and recipient were matched for the KIR genotypes (HR = 1.7; p = 0.03) without any effect on disease relapse (HR = 1.2; p = 0.57). Recipients of a KIR genotype matched graft appeared to have an improved survival. Conclusions Since GVHD is concomitant with graft-vs-leukemia (GVL) reaction, strategies to decrease GVHD in most cases have resulted in increased relapse. Matching donor and recipients for KIR genotypes can offer a significant protection against GVHD without increasing the risk of disease relapse.