Analysis of the Impact of Body Mass Index (BMI) on the Durability of Response in Patients with Aplastic Anemia Treated with Weight-Adjusted Horse Anti-Thymocyte Globulin (hATG)

Introduction: Immunosuppressive therapy (IST) with anti-thymocyte globulin (ATG), cyclosporine A (CsA) and Eltrombopag (Epag) has recently been established as standard of care in adult patients (pts.) with severe (sAA) or very severe (vsAA) aplastic anemia > 40-50 years or ineligible for transplant for other reasons. ATG works via immunosuppressive properties including T-cell depletion and induction of immune tolerance. Horse ATG (hATG) is applied for 4 days with 40 mg/kg/day based on the patient's currentbody weight. Thus, obese pts., defined by a body mass index (BMI) ≥ 30, receive higher absolute hATG dosages than non-obese pts. (BMI < 30). To date, it is unknown whether increased hATG dosages in obese pts. might have beneficial or adverse effects on AA treatment. To address the role of obesity in AA, we investigated (1) the prevalence of obesity in 334 pts. with (suspected) AA and (2) compared the overall survival (OS) and response of 89 obese and non-obese AA pts. to the treatment with hATG/CsA ±Epag.