Long-Term Outcomes of Immunosuppressive Therapy for Aplastic Anemia: A Single-Center Experience

Background. Bone marrow transplantation-ineligible aplastic anemia (AA) is most effectively treated with combined immunosuppressive therapy (IST). It yields remissions in most patients. However, it has such disadvantages as frequent relapses, incomplete hematologic recovery, and clonal evolution risk. Besides, АА is not always treated according to standard regimens. For different reasons, some AA patients receive delayed therapy or IST mono-treatment predominantly with cyclosporine A (CsA). Aim. To assess long-term IST outcomes in AA patients followed-up at the Russian Research Institute of Hematology and Transfusiology for 5 years after therapy onset. Materials & Methods. The study enrolled 30 AA patients who received IST for more than 5 years (continuous follow-up of 5.5–33 years) with monitoring of the main hemogram parameters and PNH clone size. Patients were aged 19–73 years (median 29 years). There were 8 women and 12 men. Based on international criteria, severe AA (SAA) was initially diagnosed in 18 patients, and non-severe АА (NAA) was diagnosed in 12 patients. Combined IST was administered to 22 patients (18 SAA patients and 4 NAA patients), the remaining 8 patients received ATG (n = 1) and CsA (n = 7). Results. A response to IST was achieved in 28 (93.3 %) out of 30 patients, 16 (53.3 %) of them showed complete remission. This paper documents the characteristics of hematologic recovery depending on the compliance with standard therapy regimens, as well as on the disease variant, development of late complications and clonal evolution, characteristics of pregnancy and childbirth in 4 female patients in remission. PNH clone increased in more than a half (10 out of 16) patients whose clone was initially > 2.6 %. Long-term clonal evolution to myeloid neoplasia (13 years after IST onset) was registered in 2 (6.7 %) patients with complete AA remission. Aseptic (avascular) osteonecrosis as complication was reported in 6 (20 %) followed-up patients. Conclusion. The results of the study highlight the importance of and the need for early start and adherence to standard combined IST regimens aimed at optimum therapeutic effect in both SAA and NAA patients, as well as for long-term follow-up of patients after completing IST.