Efficacy of Malononitrilamide FK778 in a Preclinical Model of Small Bowel Transplantation

Abstract

In a swine model of orthotopic small bowel transplantation, we assessed the efficacy of combined immunosuppressive therapy with low-dose tacrolimus plus FK778, compared with high-dose tacrolimus monotherapy. The small bowel was replaced in 23 piglets: group 1 (n = 5), no immunosuppression; group 2 (n = 12), oral tacrolimus to maintain whole blood trough levels between 15 and 25 ng/mL; and group 3 (n = 6), oral FK778 4 mg/kg/d, plus oral tacrolimus to maintain whole blood trough levels between 5 and 15 ng/mL. Follow-up time was limited to 60 days. Overall survival rates at 30 and 60 days were 0% and 0% in group 1, 30% and 0% in group 2, and 66% and 66% in group 3, respectively. The median survival time was 11 days in group 1, 28 days in group 2, and more than 60 days in group 3. The differences between groups 3 and 1 and between groups 3 and 2 were statistically significant. The numbers of major bacterial infections were 19 in group 2 (1.9 episodes per animal) and 3 in group 3 (0.75 episodes per animal). The infectious-related mortality rate was 70% in group 2 (7 cases) and 0% in group 3 ( P < .05). Acute cellular rejection was absent or mild in 85% of group 2 stomal biopsy specimens and in 100% of group 3 biopsy specimens. In conclusion, combination therapy of low-dose tacrolimus is potentiated by FK778 to prevent acute cellular rejection and prolong small bowel transplant survival in pigs.