The long-term survival of baboon-to-monkey kidney and liver xenografts

: The present study was undertaken to develop an optimum immunosuppressive regimen in baboon‐to‐monkey life‐supporting kidney xenografts. Baseline therapy for all groups include cyclosporine (CsA) and steroids. We compared adding (1) cyclophosphamide (CyP) at dose of 20 mg/kg/day given on post‐operative day (POD) 0, 2, 5 and 7; (2) mycophenolic mofetil (MMF) at a dose of 40 mg/kg/day by daily gavage; or (3) CyP + rapamycin (Rap). The latter group was divided into high and low dose subgroups. Untreated xenografts were rejected on POD 6, CsA alone treated xenografts survived for 35 days and CsA + CyP treated xenografts survived for 45 days. Adding MMF significantly prolonged mean survival to 111 ± 53 days, but the xenografts eventually developed rejection. Combination therapy including CsA, CyP and Rap reliably prevented xenogenic rejection and achieved a mean survival of 290 ± 30 days. However, high dose CyP + Rap led to high incidence of post‐transplant lymphoproliferation disorders (PTLD), while the incidence of PTLD was significantly less in the low dose subgroup (P