Retrospective Study of Patients With Severe Aplastic Anemia Who Relapsed After Immunosuppressive Therapy

Severe aplastic anemia (SAA) is a form of bone marrow failure and in most cases is the result of a cytotoxic T cell attack on the marrow stem cell. It is effectively treated in most patients with either immunosuppressive treatment (IST) or upfront allogeneic hematopoietic stem cell transplant (HSCT). However, in patients who are treated with IST, relapse remains an issue with a rate of 30-40%. Once relapsed, patients can be either re-treated with IST or undergo HSCT. The two most common IST regimes used for relapsed SAA are rabbit ATG (rATG) and alemtuzumab. Both rATG and alemtuzumab have been shown to have a response rate of approximately 60% in relapsed patients with similar overall survival rates of 83-85%. Previous predictors of relapse include time from diagnosis to IST, and early response to IST. Few long-term data exist on patients requiring repeat IST treatment due to relapse.