Immunosuppressive therapy using horse antithymocyte globulin (ATG
h-ATG) combined with cyclosporine (CsA) and eltrombopag is the standard care for aplastic anemia (AA) in patients without a suitable matched donor. However, in many countries, h-ATG use has been discontinued, leaving rabbit ATG (r-ATG), which has a lower response rates and poorer survival, as the only alternative. In previous studies, alemtuzumab (ALZ), a humanized monoclonal antibody targeting CD52, combined with CsA, resulted in an adequate overall response rate (ORR) in patients with AA. This study describes a multicenter, international retrospective analysis of ALZ for treating AA.We analyzed a series of patients who received subcutaneous ALZ for AA in 4 centers in Brazil and the United Kingdom from March 2009 to January 2024. We analyzed 64 ALZ treatments in 61 adult patients with AA, 76% with severe AA (SAA) or very SAA. The ORR was 59.4% at 12 months (complete, 21.9%
partial, 37.5%). Cumulative incidence (CI) of response was 54.7% at 6 months and 59.4% at 12 months. Younger patients (age <
65 years) had higher CI of response (67% vs 31%
P = .03), as did patients treated with a total dose of 103 mg (70% vs 38%
P = .02). Overall survival was 86% at 1 year, 78% at 2 years, and 70% at 4 years, significantly higher in responders (90% vs 44%
P <
.0001). Adverse events were of low grade, and infectious events were infrequent. Subcutaneous ALZ is a feasible, effective, and safe alternative to r-ATG for patients with AA requiring immunosuppressive treatment when h-ATG access is limited.