Effect of blood cyclosporine concentration on the outcome of hematopoietic stem cell transplantation from an HLA-matched sibling donor.

We retrospectively evaluated the effect of the blood cyclosporine (CsA) concentration on the outcome of allogeneic hematopoietic stem cell transplantation from an HLA-matched sibling donor in 171 patients who received a continuous infusion of CsA and short-course methotrexate to prevent graft-versus-host disease (GVHD). CsA was started at 3.0 mg/kg/day and the dose was adjusted to maintain the blood CsA concentration between 250 and 350 ng/ml. The actual dose of CsA averaged 1.9 mg/kg/day at the 3rd week after transplantation. The incidence of grade II-IV acute GVHD was 29.9%. Patient age and sex were identified as independent significant risk factors for acute GVHD. The CsA concentration during the 3rd week after transplantation most strongly affected the incidence of grade II-IV acute GVHD (RR 0.995 for an increase in CsA concentration by 1 ng/ml, P = 0.037) adjusted for other risk factors. The incidence of acute GVHD was significantly lower in patients with a 3rd-week CsA concentration higher than 300 ng/ml than in those with values between 200 and 300 ng/ml (20% vs. 35%, P = 0.036). We concluded that the blood CsA concentration at peri-engraftment period may be important in preventing acute GVHD.