Inhibitory KIR-HLA receptor-ligand mismatch in autologous haematopoietic stem cell transplantation for solid tumour and lymphoma

Abstract

Genes that encode killer Ig-like receptors (KIRs) and their HLA class I ligands segregate independently; thus, some individuals may express an inhibitory KIR gene but not its cognate ligand. We hypothesised that these patients with KIR-HLA receptor-ligand mismatch have a low risk of relapse after an autologous haematopoietic stem cell transplantation (HCT). Sixteen consecutive patients with lymphoma or solid tumour were enrolled onto a prospective study. They received high-dose busulphan and melphalan followed by autologous CD133(+) HCT. We found that 8 of the 16 patients experienced disease progression after autologous HCT, including 5 of the 6 patients (83%) with no inhibitory KIR-HLA mismatch and 3 of the 6 patients (50%) with 1 mismatched pair; none of the 4 (0%) patients with 2 mismatched pairs experienced disease progression. Survival analyses showed that inhibitory KIR-HLA mismatch was the only significant prognostic factor (P=0.01). The potential applicability of the receptor-ligand mismatch model to autologous HCTs and to patients with lymphoma or solid tumour is clinically significant because of the prevalence of the HCT procedure.

Figure 1

Significance of inhibitory KIR–HLA receptor–ligand mismatch. (A) Cumulative incidence (CI) of disease progression in patients with different numbers of receptor–ligand mismatch pairs (P=0.02). (B) Event-free survival (EFS) of patients with receptor–ligand mismatch and of those with no mismatch (P=0.01). Progression-free survival was identical to EFS because there was no transplant-related mortality.