Autoimmune hemolytic anemia (AIHA) following allogeneic hematopoietic stem cell transplantation (HSCT): A retrospective analysis and a proposal of treatment on behalf of the Grupo Español De Trasplante de Medula Osea en Niños (GETMON) and the Grupo Español de Trasplante Hematopoyetico (GETH).

Autoimmune hemolytic anemia (AIHA) is a complication of allogeneic hematopoietic stem cell transplantation (HSCT) associated with poor outcome. However, an optimal therapeutic approach is lacking. Between 2000 and 2015, 4099 allogeneic HSCT were performed in eight pediatric centers of the Grupo Español De Trasplante de Medula Osea en Niños (GETMON) and six adult centers of the Grupo Español de Trasplante Hematopoyetico (GETH). Sixty cases of AIHA were registered with a cumulative incidence of 1.5% occurring at a median of 6 months after HSCT. Patients aged less than 15 years (P=.005), and patients using cord blood (P=.005) or an HLA mismatch donor (P=.005) were more likely to develop AIHA. Most patients were lymphopenic at the time of diagnosis of AIHA, including a low number of regulatory T lymphocytes (median 3/μL). Median lines of treatment received for AIHA was 3 (range, 1-7). Almost all patients received corticosteroids (88%) and more than half received immunoglobulins or rituximab (63% and 67%, respectively). Complete resolution of AIHA was achieved in 33 of 60 cases (55%). Cumulative incidence of AIHA-related mortality was 17±6%. We found a correlation of AIHA outcome with age (better outcome in younger than 15 years, RR=1.87, P=.01) and rituximab response (higher rate of complete remission in patients responding to rituximab, RR=1.72, P=.025). We analyzed the factors involved in the response to rituximab and found a better response when there was ABO donor/receptor disparity (P=.014) and in those patients with B lymphocytes count above the median (38/μL) (P=.05).Thirty-six of 60 patients survived yielding a disease free survival of 52±8% at 40 months. In Cox analysis, age (children vs adults, HR: 8.19, CI 95%: 2.39-28.12, P=.001) and AIHA outcome (complete remission vs partial remission/non-response, HR: 4.18, CI 95%: 1.55-11.22, P=.005) were associated with a better survival. Our data suggest that patients who developed AIHA after HSCT are severely lymphopenic and have a high risk of mortality. Outcome is better in children and in patients treated with rituximab. We also propose an algorithm for treatment of AIHA after HSCT.