Sirolimus is effective for primary relapsed/refractory autoimmune cytopenia: a multicenter study

Autoimmune cytopenia includes autoimmune hemolytic anemia (AIHA), immune thrombocytopenia (ITP), and Evans syndrome (ES) caused by abnormal activation of autoimmunity and has a considerable refractory/relapse rate. To evaluate the efficacy and toxicity of sirolimus of primary relapsed/refractory autoimmune cytopenia, records of 45 patients with primary relapsed/refractory AIHA, ES, or ITP from October 2016 to January 2019 in two institutions, were collected; there were 3 pediatric patients and 42 adult patients. The median age at diagnosis was 31 (1-84) years. Patients were treated for a median of 14 (6-39) months and followed-up for a median of 18 (10-40) months. Thirty-eight patients responded to sirolimus, with 28 complete responses (CRs) and a median of 2 (2-5) months to response. Five patients had mucositis; the incidences of other adverse events were all less than 5%. Four patients relapsed, making the CR and overall response rate 46.7% and 75.6% at the end of follow-up. There were no differences in patient age, sex, time from diagnosis to sirolimus, serum sirolimus concentration, and disease distribution between CR and non-CR patients, or between responders and nonresponders, though AIHA patients were likely to relapse less and respond better. In conclusion, sirolimus is effective for patients with primary relapsed/refractory autoimmune cytopenia with a low relapse rate and good tolerance.