A Pilot Study of Rabbit Antithymocyte Globulin - TECELAC Combined with Cyclosporine and Prednisolone as Immunosuppressive Therapy for Severe Aplastic Anemia.

Immunosuppressive therapy is the treatment of choice in patients with severe aplastic anemia (SAA) not eligible for an allogeneic bone marrow transplant. We treated 10 patients with a combination of Tecelac (Biotest, Germany) (1.5 mg/kg/day for 4 days), Cyclosporine (5 mg/kg/day for 6 months) and Prednisolone (2mg/kg/day for 3 weeks and taper over 1 week). Tecelac is a rabbit anti-T cell immunoglobulin produced by Biotest Germany from rabbits immunized with human peripheral blood lymphocytes. Antibiotic and blood product support was given as required. Ten patients (8 males; 2 females) with a median age of 26 years (range: 18–40) were treated. The median time from diagnosis to treatment was 2 months (range: 1 – 4). The median absolute lymphocyte count (ALC) pre ATG was 1537/cumm (range: 1224 – 1748) while the median ALC post ATG was 40/cumm (range: 20 – 200). None of the patients developed serum sickness. Two patients expired due to bacterial infection (Staphylococcal sepsis and Escherichia Coli sepsis) on day +14 and day +40 post ATG. Response was seen in 5(62.5%) out of 8 evaluable patients. Two patients achieved complete normalization of blood counts. Two patients have become transfusion independent for 6 – 12 months of which one had a relapse after 12 months. One patient showed improvement in the absolute neutrophil count (ANC) and platelet count with a decrease in transfusion frequency. Three patients (37.5%) showed no improvement in blood counts and continue to remain transfusion dependant. At a median follow up of 22 months (16 – 30), the overall survival is 80% with a disease free survival of 37%. Rabbit ATG induces remission in a small number of patients with severe aplastic anemia and the results are comparable with some reports using equine ATG/ALG. Larger studies need to be done to evaluate the efficacy of rabbit ATG in severe aplastic anemia.