Antithymocyte globulin: a realistic approach to therapy for severe aplastic anemia.

Antithymocyte or antilymphocyte globulin (ATG or ALG) has emerged since 1978 as important therapy applicable to the majority of patients with aplastic anemia. On the basis of similarities of patient populations, nine clinical trials were selected among many for this review. A total of 209 patients with severe aplastic anemia have been analyzed. A hematologic response was observed in 113 (54%). The degree of hematologic improvement is incomplete in the majority of patients, but it is most often sustained and independent of further transfusion. The survival rate is 42% to 75% with a follow-up ranging between 12 and 55 months; three of 113 responders have had relapse. The similarities in treatment outcome suggest that different preparations of ATG or ALG carry an identical efficacious component.