Disclosures: The following people have nothing to disclose: Lisa B. VanWagner, Marina Serper, Raymond Kang, Anton I. Skaro, Josh Levitsky, Samuel Hohmann, Donald M. Lloyd-Jones Calcineurin inhibitors (CNI) induce chronic renal dysfunction. Switching CNI to mycofenolate mofetil (MMF) monotherapy remains controversial due to an increased risk of acute rejection. To safely withdraw CNI, mycophenolic INCB024360 acid (MPA) should be monitored. Aims: 1) Define a safe MPA targeted exposure (AUC). 2) Study the benefit and efficacy

of MMF monotherapy under therapeutic drug monitoring. Methods: 1) To define a safe MPA targeted exposure, 18 stable LT recipients previously treated with MMF monotherapy, were selected. Algorithms were used to determine AUC0-12h (0, H0.5, H2, H3 and H4). 2) Patients that required CNI withdrawal were selected, and prospectively followed. Before CNI withdrawal MMF, daily doses were adjusted to reach the MPA targeted previously

determined. Doxorubicin Data as ALT, glomerular filtration rate (GFR) using MDRD formula were prospectively collected at CNI withdrawal (baseline), M1, and each year until M72. Results: 1) A wide variability in MPA concentrations was observed at any time, with mean C0, C0.5, C2, C3 and C4 values at 2.4 (0.4 to 4.6), 15.2 (4.5 to 31.1), 5.2 (2.2 to 9.5), 3.3 (0.9 to 5.5) and 2.9 mg/L (0.6 to 5.3). For C0 MPA a greater than 10-fold range was observed. The mean estimated AUC0-12h value was 48.1 ±13 mg.h/L. MPA AUC0-12 did not correlate with MMF daily dose (r= 0.27, p=0.2). 2) From dec 2000 to dec 2013, 103 recipients (mean age 60.2±7.4 yrs) underwent MMF monotherapy after a mean of 6.3±3.9 yrs from LT. LT indication was alcoholic cirrhosis in 73% of cases, mean MPA AUC was at 49.3±17.1 and GFR was 47.8±16.9 ml/kg/ min. Follow up: 4 patients had

acute rejection and 2 required steroid bolus. Over time, patients did not have a significant change in term of: ALT (23.2±13.4 vs 25.7±16.2) click here and weight (80±18.2 to 80±19.1). Renal function improved significantly (GFR 47.7±15.7 to 53.7±19.6, p<0.001). This improvement occurred the first year of MMF monotherapy (GFR: 45.8±14.9 to 52.9±19.8 ml/kg/min; p<0.05), as shown by GFR evolution between 1 and 2 years: 50.8±17.1 vs 48.1 ±14.7 (ns), and also concerned patients with a low GFR at baseline (<60) 41.3±10 to 47.9±15.4 ml/kg/min p<0.05. GGT worsened (57.6±50.5 vs 79.6±92.5 p<0.001). Patients with elevated GGT after MMF monotherapy did not differ at baseline from other in terms of: age (60.3 vs 59.7), time after LT (6.9 vs 5.8), MPA AUC (50 vs 52) or weight (82 vs 78kg). Conclusion: In maintenance LT recipients, MMF monotherapy regimen is safe when a 45 mg.h/L AUC is targeted and improve renal function with low risk of acute rejection.