The Effect of KIRs Expression Profile in Donor/Recipient Pairs in HLA-Identical Sibling Hematopoietic Stem Cell Transplantation,

Abstract 4017 Objective: We investigated the distribution characteristics of KIRs expression profile in donor/recipient pairs with acute leukemia (AL) receiving HLA-identical sibling hematopoietic stem cell transplantation (sib-HSCT). We further explored the effect of KIRs expression profile in donor/recipient pairs on clinical outcome, including dynamics of donor T cell and NK cell engraftment. Methods: The genotypes of donor/recipient KIRs were determinated by polymerase chain reaction- sequence specific primer (PCR-SSP) for 80 pairs of donor/recipient receiving HLA-identical sibling hematopoietic stem cell transplantation. The multiple short tandem repeat (STR) PCR was used to evaluate the status of engraftment of donor T cells and NK cells at +14 days, 21 days, 28 days, 60 days and 90 days after transplantation in 24 cases. Results: 1. In 80 pairs of donor/recipient: (i) the KIRs were completely identical in 57.5% of donor/recipient pairs; (ii) the donors9 KIRs contained the recipients9 in 13.75% pairs; (iii) the recipients9 KIRs contained the donors9 in 17.5% of pairs; (iv) the KIRs were completely different in 11.25% pairs. The graft versus host (GVH) direction KIR-matched group was 75%. The percentage of group donor B/X and group donor A/A was 50%, respectively. 2. Comparing the patients from GVH direction KIR-matched and mismatched group, the incidence of acute (a) GVHD was 60% and 30%, respectively ( P =0.0222), and 2-year OS was 62.96% and 94.12%, respectively ( P =0.0492). Particularly, grade III-IV aGVHD rate of KIR-matched group was higher than that of non-KIR matched group(15% vs 0%). 3. Donor B/X group had a higher 2-year OS and 2-year relapse-free survival (RFS) compared with donor A/A group (89.23% vs 49.57%, P =0.0159, and 90% vs 59.71%, P =0.0239, respectively). Patients with three or less aKIRs had a lower 2-year OS (58.9% vs 92.44%, P =0.0338) and a lower RFS (65.14% vs 92.59%, P =0.0398), compared with patients with more aKIR. 4. Sequential monitoring of chimerism status of donor NK-cells in 24 cases revealed that on day+14, the percentage of full donor NK cells chimerism was higher in non-KIR matched patients than that of KIR matched patients (85.7% vs 52.9%, P =0.0456). Conclusions: Donor KIR genotype appears to have a direct impact on aGVHD, OS and RFS. Therefore, donor KIR genotype should be evaluated as an outcome predictor of the HLA-identical sib-HSCT. Disclosures: No relevant conflicts of interest to declare.