Response to Immunosuppressive Therapy with Antithymocyte Globulin (ATG) In Older Patients with Aplastic Anemia

Abstract 4374

Immunosuppressive therapy (IST) with antithymocyte globulin in combination with prednisolone and cyclosporine is the treatment of choice for patients with aplastic anemia who are ineligible for transplant either because of age or because of absence of a HLA identical donor. Limited data that exists on the role of immunosuppressive therapy in older patients with aplastic anemia suggest that responses were poorer. This retrospective analysis was aimed at determining whether older patients with aplastic anemia had an inferior response to IST compared with younger patients.

Between October 1985 to December 2010, 322 adult patients (>12 years) were treated at our centre with antithymocyte globulin (ATG) in combination with prednisolone and with/without cyclosporine. Either ATGAM (Pharmacia Upjohn, USA) at 40 mg/kg/day × 4 days or Lymphoglobulin (Pasteur Merieux, France) at 15 mg/kg/day × 5 days was used. Prednisolone at 1 mg/kg in 3 divided doses were started one day after completion of ATG and tapered from Day +14 if there was no evidence of serum sickness. Cyclosporine at the dose of 6 mg/kg/day in 2 divided doses was started once steroids were tapered and then continued for 12 months and then tapered depending upon response. Patients were divided into 3 age groups - Ages 12 – 29 [n=116], ages 30 – 49 [n = 116] and > 50 years [n = 90]. The baseline characteristics are detailed in the table below – Thirty one patients were above the age of 60 years. The older age group had significantly higher % of males, more use of ATGAM compared with Lymphogloblin and a higher number was given Cyclosporine (CSA) post ATG. The severity of aplastic anemia (severe vs non-severe) and the median time from diagnosis to administration of ATG was not significantly different between the 3 groups. The number of patients who developed serum sickness was significantly lower in the older age group (21.1%) compared to the age group of 30 – 49 (35.3%) and 12 – 29 years (48.3%) [p = 0.000]. The overall response to ATG was similar in all 3 groups (63.8% in age 12 –29, 64.7% in ages 30 – 49 and 54.4% in age > 50 yrs) [p = 0.233]. The response in patients above the age of 60 years was 51.6%. Six patients received a second course of ATG while 3 patients underwent HLA identical sibling donor transplantation. At a median follow up of 32 months (range: 1 –145), 221 patients (68.6%) are alive. The overall survival is similar for the older age group compared with the younger age groups (66.7% with age>50 years, 68.1% with age 30–49 and 70.7% with age 12 –29) [p= 0.817]. In conclusion, immunosuppressive therapy with ATG has a reasonable outcome in older patients (> 50 years) with aplastic anemia.