Donor T-cell chimerism and early post-transplant cytomegalovirus viremia in patients treated with myeloablative allogeneic hematopoietic stem cell transplant

Background: Cytomegalovirus (CMV) is a common infection after myeloablative allogeneic hematopoietic stem cell transplant (M-alloHSCT). Achievement of complete donor T-cell chimerism (CDC-T) post transplant is a measure of immune reconstitution. We investigated the association between CDC-T post M-alloHSCT and the incidence of CMV viremia. Methods: We retrospectively reviewed all CMV and chimerism results of 47 patients for the first 6 months post M-alloHSCT. CDC-T was analyzed as a time-varying covariate for association with post M-alloHSCT CMV viremia. Results: CMV viremia occurred in 15 (32%) and CDC-T was achieved in 38 (81%) recipients within the first 6 months post M-alloHSCT. On univariable analysis, increased CMV viremia was seen among patients with CDC-T (hazard ratio 2.81 [P = 0.07, 95% confidence interval = 0.93-8.52]). A 30-day landmark analysis showed that the incidence of CMV viremia at 6 months (regardless of recipient CMV serostatus) was 50% among those who had achieved CDC-T by day 30, and 23% among those who had not (P = 0.06). Conclusion: We conclude that shorter time to CDC-T may be associated with higher risk of CMV viremia. If confirmed in a larger cohort, this might be a marker for risk stratification in the management of CMV in this population.