Relationship between certain HLA alleles and the risk of cytomegalovirus reactivation following allogeneic hematopoietic stem cell transplantation.

INTRODUCTION

Evidence is emerging to support an association between certain human leukocyte antigen (HLA) alleles and the risk of cytomegalovirus (CMV) reactivation following allogeneic hematopoietic stem cell transplant (allo-HSCT). The primary aim of this study was to identify HLA alleles associated with resistance or susceptibility to CMV reactivation.

METHODS

We studied 586 adults who underwent allo-HSCT for high-risk hematological malignancies. High-resolution HLA typing data were available for recipients and donors. HLA class I and II alleles observed at a frequency of >5% in our population were included in the analysis. A CMV viremia level of more than 200 IU/ml on weekly monitoring was considered to be indicative of CMV reactivation.

RESULTS

The median follow-up time in surviving patients was 21 months (range 4-74 months). The cumulative incidence of CMV reactivation at 6 months in the entire cohort was 55% (95% confidence interval [CI] 50.8%-59.2%). Mismatched donors, increasing recipient age, occurrence of acute graft versus host disease and recipient CMV seropositivity were associated with an increased risk of CMV reactivation. HLA B*07:02 (hazard ratio 0.59, 95% CI 0.40-0.83) was associated with a decreased risk of CMV reactivation. Patients who developed CMV reactivation had a lower incidence of relapse, higher transplant-related mortality (TRM) and lower overall survival (OS) than those without CMV reactivation. There was an adverse correlation of OS and TRM with increasing numbers of CMV reactivations.

CONCLUSION

We observed that HLA B*07:02 was associated with a decreased risk of CMV reactivation. CMV reactivation was associated with lower relapse post-transplant, but this did not translate into a survival benefit due to higher TRM.