Background: There has been much evidence that immune-mediated stem cell injury may have a significant role in the pathogenesis of aplastic anemia, and as a result
immunosuppressive therapy has become known as an effective treatment for patients with aplastic anemia. There have been no reports regarding the long-term follow-up of
immunosuppressive therapy of patients with aplastic anemia in Korea. Therefore, we evaluated the response to immunosuppressive therapy for 47 patients with aplastic
anemia, investigating the long-term survival, relapse rate and secondary clonal hematologic diseases.
Methods: Antithymocyte globulin(ATG) or antilymphocyte globulin(ALG) was given with cyclosporin A(CsA) to 39 patients(ATG+CsA 27, ALG+CsA 12), and to 8 patients,
ATG or ALG alone was given(ATG 6, ALG 2). ATG was administered for 5(or 8) days, and ALG was administered for 5 days. CsA was orally begun with ATG or ALG for a median total of 4.5(3∼14) months.
Results:
1) Response: Among 47 patients, 30(63.8%) responded; 11 showed complete response(CR) and 19 showed partial response(PR).
2) Factors affecting response: Responses were equally distributed when patients were stratified for age, neutrophil counts and drug regimens.
3) Survival: Median duration of follow-up was 36(6∼84) months. Actuarial survival at 1 year was 100% in responders and 7.6% in nonresponders, and the 7-year actuarial
survival rate was 94% and 76%, respectively(P value = 0.13).
4) Relapse: Relapse occurred in 4 of 30 responding patients. Relapse in patients with CR was not observed during follow-up. The risk of relapse was 12% at 2 years and
22% at 6 years.
5) Treatment outcome according to disease duration: There was no significant difference in response rate between patients treated within 4 months and beyond 4 months after diagnosis. But the latter group showed a significantly higher relapse rate than the former(4% vs 60%; P value = 0.01).
6) Side effects and complications: There were no serious side effects requiring discontinuation of immunosuppressive therapy. Evolution to secondary clonal hematologic
diseases was not observed during follow-up.
Conclusion: Our results of immunosuppressive therapy show the excellent long-term outcome. A prospective study is needed for the establishment of the adequate treatment
duration of CsA and the follow-up period for the evaluation of the response of treatment.

Keywords: Aplastic anemia, Immunosuppressive therapy,