Quantification of tacrolimus in PBMCs samples in pediatric liver transplant patients and correlation with tacrolimus whole blood concentration

s / Digestive and Liver Disease 46 (2014) e71–e84 e73 QUANTIFICATION OF TACROLIMUS IN PBMCS SAMPLES IN PEDIATRIC LIVER TRANSPLANT PATIENTS AND CORRELATION WITH TACROLIMUS WHOLE BLOOD CONCENTRATION Michele Pinon1,∗, Pier Luigi Calvo1, Antonio D’Avolio2, Debora Pensi2, Andrea Brunati3, Roberto Canaparo4, Amedeo De Nicolo2, Giulia Carbonaro3, Alessia Cerrina3, Giovanni Di Perri2, Renato Romagnoli3, Cristiana Barbera1, Mauro Salizzoni3 1 Department of Pediatric Gastroenterology and Hepatology, Regina Margherita Children’s Hospital, Azienda Ospedaliera Citta della Salute e della Scienza, University of Turin, Turin, Italy 2 Unit of Infectious Diseases, University of Turin, Department of Medical Sciences, Amedeo di Savoia Hospital, Turin, Italy 3 Liver Transplantation Center, Azienda Ospedaliera Citta della Salute e della Scienza, University of Turin, Turin, Italy 4 Department of Drug Science and Technology, University of Turin, Turin, Italy Objective: Therapeutic drug monitoring (TDM) of tacrolimus in whole blood is essential to optimize clinical outcomes and reduce toxicity. However, the relationship between blood concentrations and therapeutic efficacy is unclear, probably because it does not reflect tacrolimus concentration at the active site. In this preliminary study, our aims were to validate a newmethod for tacrolimus quantification into the target cells (peripheral blood mononuclear cells, PBMCs), in a cohort of 24 pediatric liver recipients after a median follow-up of 5.23 years. Moreover, we analyzed the influence of ABCB1 (3435C>T and 1199A>G), CYP3A*3 and CYP3A4*22 polymorphisms on the intralymphocyte distribution of tacrolimus. Methods: PBMCs were collected using CPT tubes; cells count and the mean cellular volume were evaluated with a coulter counter. Tacrolimus concentration was quantified, after cell lyses, using ultra performance liquid chromatographywith tandemmass inpositive ionmode, coupledwith thenewautomatedon-line solid phase extraction technology. Results: A median value of 49.5ng/mL (range 14.4–358.9) of tacrolimus PBMCs concentration was found, corresponding to a 12.7-fold wider range than the whole blood levels simultaneously analyzed. Although a significant correlation with mean tacrolimus blood levels could be observed, tacrolimus intracellular accumulation tended to be higher in ABCB1 G/A, although not statistically significantly, and in CYP3A5*3/*3 recipients. Conclusions:Although tacrolimus PBMCs concentration cannot be considered as a routine test yet, this method could bemore predictive of efficacy and toxicity of immunosuppressive therapy than whole blood levels. Further studies are required to evaluate the relationship with clinical outcomes. http://dx.doi.org/10.1016/j.dld.2014.07.025 LIVING DONOR LIVER TRANSPLANT (LDLT): THE PATIENT PERSPECTIVE Andrea Pietrobattista1,∗, Manila Candusso1, Maria Sole Basso1, Chiara Grimaldi2, Fabrizio Di Francesco2, Lidia Monti3, Jean De Ville De Goyet2, Giuliano Torre1 1 USC Epatogastroenterologia e Nutrizione, Ospedale Pediatrico Bambino Gesu, Roma, Italy 2 USC Chirurgia epato-biliare, Ospedale Pediatrico Bambino Gesu, Roma, Italy 3 USC Radiologia, Ospedale Pediatrico Bambino Gesu, Roma, Italy Objective: To evaluate the outcome of living liver donor transplantation in children. Methods: Retrospective analysis. Results: We performed 23 LDLTs out of 105 transplants in the past 5 years inRome, and thenumberhas been increasing; themain indication is cirrhosis in biliary atresia (20 cases, 87%) but it has been performed also in metabolic diseases such as primary oxalosis, MSUD and propionic academia. No recipient died, themean age at transplantwas 29.3months (SD 28.6, r. 6–132), themeanweight 13kg (SD6.7, r. 5.5–30.3), after amean144daywaiting list time (SD 250, r. 0–1040); the mean PELD score was 20 (SD 12, r. 0–38). The mean ischemic time was 244min in LDLT vs 517.3min in cadaveric transplants. The mother was the donor in 13 children, in one a relative; no death. Surgical complications occurred in 8 children (34.7%), 2 out of these in one baby; the rate is similar in cadaveric recipients (33.7%), Rejectionwasdiagnosed in47.8%of cases, biliary stenosis in 2 cases, resolved by percutaneous biliary drainage (1) and by surgery (1); one child reported portal thrombosis, treated by Meso-Rex shunt. No living donor reported any complication. Conclusions: LDLT is an important tool in dealing childrenwith end-stage liver disease, mainly if cadaveric donors are lacking; it could be a safe choose even in metabolic disorders, with an heterozygote donor. http://dx.doi.org/10.1016/j.dld.2014.07.026