Effect of Early Posttransplantation Tacrolimus Concentration on the Development of Acute Graft-versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation from Unrelated Donors

Only limited data are available regarding the relationship between blood concentration of tacrolimus and its efficacy in preventing acute graft-versus-host disease (aGVHD). We retrospectively evaluated the effects of the whole blood concentration of tacrolimus, which was measured by an automated microparticle enzyme immunoassay, early after allogeneic hematopoietic stem cell transplantation (HSCT) upon the development of aGVHD. Sixty patients, who underwent allogeneic HSCT from serologically human-leukocyte antigen-matched unrelated donors and received continuous infusion of tacrolimus with short-term methotrexate for GVHD prophylaxis, were included in this study. The target range of the blood concentration of tacrolimus was set at 10 to 20 ng/mL, and the level was maintained within this range in all patients. However, the mean blood concentration of tacrolimus during the third week after HSCT was significantly associated with the grades of aGVHD (17.3 ± 2.1 in patients with grades 0-I vs 15.9 ± 2.8 in II-IV and 14.8 ± 2.1 in III-IV; P < .05 and <.01, respectively). Multivariate analysis also demonstrated that higher age (≥35) of donor (odds ratio [OR] = 4.28) and lower mean blood concentrations of tacrolimus during the second (OR = 0.75; 95% confidence interval [CI]: 0.58-0.98) and third weeks (OR = 0.76; 95% CI: 0.58-0.98) after HSCT were significant risk factors for grades II-IV aGVHD (P < .05). We conclude that the early posttransplantation blood concentration of tacrolimus had a significant impact on the development of moderate-to-severe aGVHD after allogeneic HSCT from an unrelated donor.