M. Buchler

Individualized mycophenolate mofetil dosing based on drug exposure significantly improves patient outcomes after renal transplantation.

Efficacy and safety of mycophenolate mofetil (MMF) may be optimized with individualized doses based on therapeutic monitoring of its active metabolite, mycophenolic acid (MPA). In this 12‐month study, 137 renal allograft recipients from 11 French centers receiving basiliximab, cyclosporine A, MMF and corticosteroids were randomized to receive either concentration‐controlled doses or fixed‐dose MMF. A novel Bayesian estimator of MPA AUC based on three‐point sampling was used to individualize doses on posttransplant days 7 and 14 and months 1, 3 and 6. The primary endpoint was treatment failure (death, graft loss, acute rejection and MMF discontinuation). Data from 65 patients/group were analyzed. At month 12, the concentration‐controlled group had fewer treatment failures (p = 0.03) and acute rejection episodes (p = 0.01) with no differences in adverse event frequency. The MMF dose was higher in the concentration‐controlled group at day 14 (p < 0.0001), month 1 (p < 0.0001) and month 3 (p < 0.01), as were median AUCs on day 14 (33.7 vs. 27.1 mg•h/L; p = 0.0001) and at month 1 (45.0 vs. 30.9 mg•h/L; p < 0.0001). Therapeutic MPA monitoring using a limited sampling strategy can reduce the risk of treatment failure and acute rejection in renal allograft recipients 12 months posttransplant with no increase in adverse events.

Optimization of Initial Tacrolimus Dose Using Pharmacogenetic Testing

Retrospective studies have demonstrated that patients who are expressors of cytochrome P4503A5 (CYP3A5) require a higher tacrolimus dose to achieve a therapeutic trough concentration (C0). The aim of this study was to evaluate this effect prospectively by pretransplantation adaptation. We randomly assigned 280 renal transplant recipients to receive tacrolimus either according to CYP3A5 genotype or according to the standard daily regimen. The primary end point was the proportion of patients within the targeted C0. Secondary end points included the number of dose modifications and the delay in achieving the targeted C0. In the group receiving the adapted dose, a higher proportion of patients had values within the targeted C0 at day 3 after initiation of tacrolimus (43.2% vs. 29.1% P = 0.03); they required fewer dose modifications, and the targeted C0 was achieved by 75% of these patients more rapidly. The clinical end points were similar in the two groups. Pharmacogenetic adaptation of the daily dose of tacrolimus is associated with improved achievement of the target C0. Whether this improvement will affect clinical outcomes requires further evaluation.

Efficacy on Renal Function of Early Conversion from Cyclosporine to Sirolimus 3 Months After Renal Transplantation: Concept Study

Sirolimus (SRL) allows to minimize the use of cyclosporine (CsA), but de novo administration after transplantation is associated with various complications. We report a prospective, open‐label, multicenter randomized study to evaluate conversion from a CsA‐based regimen to a SRL‐based regimen 3 months after transplantation. One hundred ninety‐two of a total of 237 patients were eligible at 3 months to be converted to SRL (n = 95) or to continue CsA (n = 97). All patients were also given mycophenolate mofetil (MMF) and oral steroids, planned to be discontinued at month 8. The primary endpoint, the clearance estimated according to Cockcroft and Gault at week 52, was significantly better in the SRL group (68.9 vs. 64.4 mL/min, p = 0.017). Patient and graft survival were not statistically different. The incidence of acute rejection episodes, mainly occurring after withdrawal of steroids, was numerically but not statistically higher in the SRL group (17% vs. 8%, p = 0.071). Sixteen patients discontinued SRL, mainly for adverse events (n = 11), and seven patients discontinued CsA for renal failure or acute rejection. Significantly, more patients in the SRL group reported aphthous, diarrhea, acne and high triglyceride levels. Conversion CsA to SRL 3 months after transplantation combined with MMF is associated with improvement in renal function.

Ribavirin for Chronic Hepatitis E Virus Infection in Transplant Recipients

BACKGROUND There is no established therapy for hepatitis E virus (HEV) infection. The aim of this retrospective, multicenter case series was to assess the effects of ribavirin as monotherapy for solid-organ transplant recipients with prolonged HEV viremia. METHODS We examined the records of 59 patients who had received a solid-organ transplant (37 kidney-transplant recipients, 10 liver-transplant recipients, 5 heart-transplant recipients, 5 kidney and pancreas-transplant recipients, and 2 lung-transplant recipients). Ribavirin therapy was initiated a median of 9 months (range, 1 to 82) after the diagnosis of HEV infection at a median dose of 600 mg per day (range, 29 to 1200), which was equivalent to 8.1 mg per kilogram of body weight per day (range, 0.6 to 16.3). Patients received ribavirin for a median of 3 months (range, 1 to 18); 66% of the patients received ribavirin for 3 months or less. RESULTS All the patients had HEV viremia when ribavirin was initiated (all 54 in whom genotyping was performed had HEV genotype 3). At the end of therapy, HEV clearance was observed in 95% of the patients. A recurrence of HEV replication occurred in 10 patients after ribavirin was stopped. A sustained virologic response, defined as an undetectable serum HEV RNA level at least 6 months after cessation of ribavirin therapy, occurred in 46 of the 59 patients (78%). A sustained virologic response was also observed in 4 patients who had a recurrence and were re-treated for a longer period. A higher lymphocyte count when ribavirin therapy was initiated was associated with a greater likelihood of a sustained virologic response. Anemia was the main identified side effect and required a reduction in ribavirin dose in 29% of the patients, the use of erythropoietin in 54%, and blood transfusions in 12%. CONCLUSIONS This retrospective, multicenter study showed that ribavirin as monotherapy may be effective in the treatment of chronic HEV infection; a 3-month course seemed to be an appropriate duration of therapy for most patients.

Immunoprophylaxis with basiliximab compared with antithymocyte globulin in renal transplant patients receiving MMF-containing triple therapy.

Acute graft rejection remains a major problem in renal transplant recipients, and there is no consensus on the optimal immunosuppressive strategy. Immunoprophylaxis with Thymoglobulin® or basiliximab has significantly reduced the incidence of acute rejection episodes and graft loss following kidney transplantation. This open, randomized, multicenter study investigated the efficacy and tolerability of basiliximab (20 mg day 0– day 4) plus early cyclosporine from day 0 (n = 50) compared with Thymoglobulin® plus delayed cyclosporine (n = 50) in adult kidney transplant patients. In addition, all patients received steroids and mycophenolate mofetil (MMF) at standard doses from day 0. Patient and graft survival rates at 12 months were 98 and 94% in the basiliximab group, respectively, compared with 100 and 96% in the Thymoglobulin® group. The incidences of biopsy‐confirmed acute rejection (8.0% in each group) and treatment failure (14% in the basiliximab group vs. 8% in the Thymoglobulin group) were comparable in the two groups. There was a nonsignificant tendency to more dialysis (14 vs. 6%), and fewer cytomegalovirus (CMV) infections (p = 0.005) in the basiliximab group, but the percentage of clinical CMV was not different between the two groups (6 vs. 12%). Both strategies give excellent results, despite the differences in patterns, in nonhyperimmunized patients receiving their first cadaveric renal allograft.

CYP3A5 and MDR1 Genetic Polymorphisms and Cyclosporine Pharmacokinetics After Renal Transplantation

The immunosuppressive drug cyclosporine (INN, ciclosporin), whose pharmacokinetic characteristics vary greatly among individuals, is a substrate for cytochrome P450 (CYP) 3A and P‐glycoprotein, the product of the multidrug resistance 1 (MDR1) gene. Some of the single nucleotide polymorphisms (SNPs) in these genes are associated with deficient protein expression and reduced in vivo activity. We postulated that, in renal transplant recipients, these SNPs could be associated with interindividual variations in cyclosporine pharmacokinetics.

Evidence that Clearance of Hepatitis C Virus RNA after α-Interferon Therapy in Dialysis Patients Is Sustained after Renal Transplantation

To date, there is no available treatment of hepatitis C virus (HCV) infection after renal transplantation (RT). Among 55 anti-HCV-positive/HCV RNA-positive hemodialysis patients who were treated with IFN-alpha (9 MU/wk during 6 or 12 mo), 21 of them (38%) had a sustained virologic response. Of these, 16 (76%) underwent RT 38 mo (range, 2 to 57 mo) after alpha-IFN therapy. There were 13 men and 3 women aged 46 yr (range, 27 to 68 yr). At RT, HCV serology was still positive in 15 patients, and HCV viremia was negative in all patients. Immunosuppression relied on anticalcineurin agents with or without steroids and/or antimetabolites; in addition, 12 of them received induction therapy with antithymocyte globulins. At the last follow-up after RT, at 22.5 mo (range, 2 to 88 mo), HCV viremia remained negative in all patients. Moreover, HCV RNA was not present in peripheral blood mononuclear cells when assessed in eight patients. HCV serology was found to be still positive in 13 patients. Three patients presented with acute rejection, one presented with a suppurative lymphocele, one died from a sepsis, and four presented with a cytomegalovirus infection. None of them developed posttransplant diabetes mellitus. In conclusion, hemodialysis patients waiting for a RT need to be treated with alpha-IFN because when HCV RNA clearance occurred, they experienced no relapse after transplantation despite chronic immunosuppressive treatment.

Sirolimus Versus Cyclosporine in Kidney Recipients Receiving Thymoglobulin®, Mycophenolate Mofetil and a 6-Month Course of Steroids

To evaluate the efficacy and tolerance of a calcineurin inhibitor (CNI)‐free regimen, 145 renal recipients were prospectively randomized to receive either sirolimus (n = 71) or cyclosporine (CsA; n = 74). All patients received polyclonal antilymphocyte antibodies, mycophenolate mofetil (MMF) and steroids (6 months). The primary endpoint, estimated glomerular filtration rate (eGFR) was not significantly different at 12 months comparing sirolimus‐ and CsA‐treated patients (60 ± 27 vs. 57 ± 21 mL/min). At 12 months, patient and graft survival, incidence of biopsy‐proven rejection and rates of steroid withdrawal were not statistically different (97% vs. 97%; 90% vs. 93%; 14.3% vs. 8.6% and 82.8% vs. 84.1%, respectively). Delayed and slow graft function (SGF) was not significantly different (18.6% vs. 12.3% and 11.4% vs. 13.7%, respectively). In patients who remained on treatment according to protocol at 12 months, eGFR was significantly higher with sirolimus (69 ± 19 vs. 60 ± 14 mL/min, p = 0.01). Overall study drug discontinuation rates were 28.2% with sirolimus and 14.9% with CsA. Adverse events (wound complications, mouth ulcers, diarrhea, hypokalemia, bronchopneumonia) and proteinuria >0.5 g/24h (38.8% vs. 5.6%, p < 0.001) were significantly more frequent in sirolimus‐treated patients. Cytomegalovirus (CMV) infections were significantly less frequent with sirolimus (6% vs. 23%, p < 0.01). A CNI‐free regimen using sirolimus‐MMF can achieve excellent renal function, but patients on sirolimus experienced a high rate of adverse events and study drug discontinuation.

Early Low-Grade Proteinuria: Causes, Short-Term Evolution and Long-Term Consequences in Renal Transplantation

Proteinuria 1 year after transplantation is associated with poor renal outcome. It is unclear whether low‐grade (<1 g/24 h) proteinuria earlier after transplantation and its short‐term change affect long‐term graft survival. The effects of proteinuria and its change on long‐term graft survival were retrospectively assessed in 484 renal transplant recipients. One‐ and 3‐month proteinuria correlated with donor age, donor cardiovascular death, prolonged cold and warm ischemia times and acute rejection. One‐ and 3‐month proteinuria (per 0.1 g/24 h, hazard ratio (HR): 1.07 and 1.15, p < 0.0001)—especially low‐grade proteinuria (HR: 1.20 and 1.26, p < 0.0001)—were powerful, independent predictors of graft loss. Its short‐term reduction correlated with arterial pressure (AP) (the lower the 3‐month diastolic and 12‐month systolic AP, the lower the risk of increasing proteinuria during 1–3 months and 3–12 months periods, respectively: Odds ratio (OR) per 10 MmHg: 0.78, p = 0.01 and 0.85, respectively, p = 0.02), and was associated with decreased long‐term graft loss (per 0.1 g/24 h: HR: 0.88 and 0.98, respectively, p < 0.0001), independently of initial proteinuria. Early low‐grade proteinuria due to pre‐transplant renal lesions, ischemia‐reperfusion and immunologic injuries is a potent predictor of graft loss. Short‐term reduction in proteinuria is associated with improved long‐term graft survival.

Complement Mutation-Associated De Novo Thrombotic Microangiopathy Following Kidney Transplantation

Mutations in one or more genes encoding complement‐regulatory proteins predispose to atypical hemolytic uremic syndrome (aHUS) and its recurrence following kidney transplantation. We evaluated plasma complement level and performed a screening for mutations in genes encoding complement Factors H and I (CFH, CFI) and membrane cofactor protein (MCP) in 24 kidney transplant recipients experiencing de novo thrombotic microangiopathy (TMA). Six patients presented with low C3 and/or low Factor B levels suggestive complement alternative pathway. A mutation in the CFH or CFI gene was found in 7/24 patients (29%), two of whom had a mutation in both genes. On the contrary, no mutation was identified in a control kidney transplant patients group (n = 25) without TMA. Patients with or without mutations were similar with regard to clinical features. Eight out of 24 patients lost their graft within 1 year of posttransplantation including six patients with a CFH mutation or a decrease of C3 or CFB in plasma. To conclude, kidney transplant patients with de novo TMA exhibit an unexpectedly high frequency of CFH and CFI mutations. These results suggest that genetic abnormalities may represent risk factors for de novo TMA after kidney transplantation and raise the question of the best therapeutic strategy.