Treatment of severe aplastic anemia using antithymocyte globulin with or without an infusion of HLA haploidentical marrow.

Nineteen patients with severe aplastic anemia were treated with a 4-day course of horse-anti-human thymocyte globulin (ATG). Thirteen of these patients also received an infusion of HLA one haplotype-identical bone marrow. Toxicity of ATG included fever, chills, rash, arthralgias and elevated liver function tests. Platelet transfusion requirements increased during therapy. Eleven patients died 0.2-9.4 months after beginning ATG therapy. None of the 11 patients had any improvement in hematologic status prior to death. The eight surviving patients have been followed for at least 24 months. Six had evidence of hematologic improvement within 6-8 weeks after ATG therapy and are transfusion-independent. The other two patients improved more than one year after treatment. Survival after ATG therapy did not correlate with the presumed etiology of aplasia, duration of aplasia, patient age or sex, prior therapy, or admission granulocyte count. Addition of bone marrow infusion to ATG treatment also did not affect survival. This study demonstrated the necessity for a randomized trial of ATG versus supportive care alone for the treatment of severe aplastic anemia.