ASP2409, A Next-Generation CTLA4-Ig, Versus Belatacept in Renal Allograft Survival in Cynomolgus Monkeys.

Belatacept is the first costimulatory blockade agent approved for maintenance immunosuppression in kidney transplant recipients. Clinical results have indicated that belatacept is associated with superior renal function and improved metabolic profile; however, higher incidence of acute rejection and posttransplant lymphoproliferative disorder are the shortcomings of this agent. In this study, ASP2409, a new cytotoxic T-lymphocyte associated protein 4-immunoglobulin possessing 14-fold higher in vitro CD86 binding affinity than belatacept, was tested for renal allograft survival in cynomolgus monkeys. ASP2409 monotherapy dose-dependently prolonged renal allograft survival. Low-dose ASP2409 in combination with a subtherapeutic dose of tacrolimus showed much longer median survival time than monotherapy. Similar allograft survival results were observed in regimens based on high-dose ASP2409, belatacept, and therapeutic-dose tacrolimus. The results of renal allograft histopathology with high-dose ASP2409-based regimens were not inferior to the belatacept-based regimen. Moreover, higher frequencies of FoxP3-positive regulatory T cells in renal allografts were observed in ASP2409- and belatacept-based regimens compared with tacrolimus-based regimens. No serious side effects related to ASP2409 administration were found during the study. These data suggest that ASP2409 is a promising candidate for calcineurin inhibitor-sparing or -avoidance regimens.

Conversion from calcineurin inhibitors to sirolimus in kidney transplant recipients: a retrospective cohort study.

BACKGROUND: Replacing a calcineurin inhibitor (CNI) with sirolimus (SRL) may preserve kidney graft function. However, at the present time, only short follow-up after conversion is available. The aim of this study was to assess whether conversion from a CNI-based to an SRL-based maintenance regimen was safe and effective. MATERIALS AND METHODS: We performed a retrospective cohort study among kidney graft patients whose CNI was withdrawn to be replaced by SRL. Two-tailed paired t tests were used to compare glomerular filtration rates (GFRs) and proteinuria levels before and up to 2 years after conversion. We used linear regression to determine the factors associated with changes in renal function after conversion. RESULTS: The 193 study subjects had a mean GFR at conversion of 41 +/- 16 mL/min/1.73 m(2) a median proteinuria level of 0 g/L (interquartile range = 0-0.15). After conversion, the GFR was stable: at 1 year, the change was -0.34 mL/min/1.73 m(2) (95% confidence interval [CI] = -2.71, 2.03) and at 2 years, -0.96 mL/min/1.73 m(2) (95% CI = 4.26, 2.34). There was a small but significant increase in dipstick proteinuria at 1 year of +0.5 g/L, (95% CI = 0.20, 0.75). On multivariate analysis, proteinuria > or = 1 g/L at the time of conversion was the only predictor of deteriorating GFR at 1 year (beta: -7.91 mL/min/1.73 m(2); 95% CI = -14.10, -1.70). SRL had to be discontinued in 31% of patients. CONCLUSION: Conversion from CNI to SRL resulted in stable graft function at 2 years and in a slight increase in proteinuria. Despite the relatively high reconversion rate, this strategy offers a reasonable alternative to CNIs for most patients.

Calcineurin inhibitor minimization in the Symphony study: observational results 3 years after transplantation.

The Symphony study showed that at 1 year posttransplant, a regimen based on daclizumab induction, 2 g mycophenolate mofetil (MMF), low-dose tacrolimus and steroids resulted in better renal function and lower acute rejection and graft loss rates compared with three other regimens: two with low-doses of cyclosporine or sirolimus instead of tacrolimus and one with no induction and standard cyclosporine dosage. This is an observational follow-up for 2 additional years with the same endpoints as the core study. Overall, 958 patients participated in the follow-up. During the study, many patients changed their immunosuppressive regimen (e.g. switched from sirolimus to tacrolimus), but the vast majority (95%) remained on MMF. During the follow-up, renal function remained stable (mean change: -0.6 ml/min), and rates of death, graft loss and acute rejection were low (all about 1% per year). The MMF and low-dose tacrolimus arm continued to have the highest GFR (68.6 +/- 23.8 ml/min vs. 65.9 +/- 26.2 ml/min in the standard-dose cyclosporine, 64.0 +/- 23.1 ml/min in the low-dose cyclosporine and 65.3 +/- 26.2 ml/min in the low-dose sirolimus arm), but the difference with the other arms was not significant (p = 0.17 in an overall test and 0.077, 0.039 and 0.11, respectively, in pair-wise tests). The MMF and low-dose tacrolimus arm also had the highest graft survival rate, but with reduced differences between groups over time, and the least acute rejection rate. In the Symphony study, the largest ever prospective study in de novo kidney transplantation, over 3 years, daclizumab induction, MMF, steroids and low-dose tacrolimus proved highly efficacious, without the negative effects on renal function commonly reported for standard CNI regimens.

Renal cell carcinoma in kidney allografts: a case series from a single center.

In kidney transplant recipients, renal cell carcinoma (RCC) occurs either in the native kidney or, less frequently, in the grafted kidney. Here, we report a series of rare cases involving 5 patients from a single center who developed RCC in their grafts. The diagnosis was made serendipitously by ultrasound. The time lapse post-transplant varied from 4 to 17 years. Surgical treatment consisted of nephron-sparing surgery (NSS) in four cases and a secondary radical nephrectomy in one case. All tumors were less than 4 cm in diameter. The histopathology was clear cell type in four cases and papillary RCC in one case. Patients treated by NSS retained kidney function for 2 years or more, and none of them presented early neoplasia recurrence. In conclusion, NSS can be performed safely in grafted kidneys to treat incidental RCC. It prevents an immediate return to dialysis for patients.

Immunological evaluation of combination therapy with tacrolimus and sirolimus on long-term allograft survival in nonhuman primates.

UNLABELLED: We reported that a 60-day course of combination therapy with tacrolimus and sirolimus induced long-term survival of renal allograft after withdrawal of immunosuppressants in Vervet monkeys. In the present study, the mechanism of drug-induced allograft survival was evaluated via Th1/Th2 cytokines, apoptosis and MLC activity in primates. MATERIALS AND METHODS: Cytokines were evaluated by ELISA. MLR and CTL assays were performed by incorporation of 72 hours (3)H-TdR and 4 hours (51)Cr release assay. RESULTS: A 60-day course of tacrolimus with sirolimus resulted in long-term survival of kidney allografts. (67% > 100 days) without intermittent acute rejection. Low sensitivity to MLR was seen in long-term renal allograft survival among monkeys treated with tacrolimus and sirolimus. Increased levels of CD3(+)CD8(+), CD3(+)/CD56(+) NKT cells and CD86(+)CD8(-)CD11(+) dendritic cells were observed. A population of high expression of CD4(+)FasL(+) was detected. In addition, the concentrations of IL-2 and IFN-gamma from long-term allograft surviving monkeys was not significantly increased, rather a late phase dominance of Th2, IL-4, IL-10, and TGF-beta was found correlated with long-term survival of recipients. In conclusion, the mechanism of tacrolimus and sirolimus induced long-term allograft survival in primates relates to up-regulated FasL expression, NKT cells and dendritic cells, with downregulation of MLR sensitivity. It is also associated with late-dominant expression of Th2 cytokines.

Total cholesterol correlates with cyclosporine C2 levels in kidney transplant recipients under maintenance immunosuppression.

The aim of this study was to assess the relationship between cyclosporine (CyA) trough level (C0) and 2-hour postdose (C2) and total cholesterol (TC) in kidney transplant (KT) recipients on Neoral maintenance immunosuppression. In KT recipients who had more than 5 years of follow-up, stable graft function, and stable Neoral dose, we measured C2 and C0 blood levels, serum creatinine, mean total cholesterol (TC) over the last 5 years, prednisone dose, use of beta-blockers and thiazides. Correlations between C0 and C2 levels and TC were performed with the Pearson coefficient. Receiver operating characteristics (ROCs) were used to define the threshold with greater accuracy for significant variables at the correlation test. Statistical tests were performed with SPSS 9.5 The C2 correlated with TC (0.31; P=.008) whereas C0 did not. The C2 level was an independent predictor for TC after adjusting for recipient age, gender, dose of prednisone, creatinine clearance, and use of beta-blockers and thiazides (B coefficient=1.124(E-3); P=.009). A threshold C2 value of 700 microg/L yielded to a TC level of 5.2 mmol/L. This is the first study to report a correlation between C2 levels and TC. Although C2 explained a small fraction of TC variability, it is an independent predictor of TC in KT recipients on Neoral maintenance immunosuppression. A long-term C2 value under 700 microg correlates with better control of hypercholesterolemia.

Compromised kidney graft rejection response in Vervet monkeys after withdrawal of immunosuppressants tacrolimus and sirolimus.

BACKGROUND: In nonprimates, organ allografts are often not rejected after withdrawal of immunosuppression. In this study, we examined whether such a phenomenon also occurs in primates. METHODS: Vervet monkeys were transplanted with renal allografts and treated for 60 days with tacrolimus, or tacrolimus plus sirolimus. The drugs were totally withdrawn on day 61. The survival of the monkeys was monitored, and their response to donor- or third party-derived alloantigens was examined in vivo and in vitro. RESULTS: The majority (80-100%) of the grafts survived for at least additional 30 days with no signs of acute rejection. The compromised rejection is donor-specific, because recipient monkeys failed to reject a donor-derived skin graft, but a third-party skin graft was rejected. In vitro mixed lymphocyte reaction and interleukin-2 production in the mixed lymphocyte reaction between the recipients and their donors or between the recipients and a third party had no discernable patterns, and thus did not reflect the in vivo status of the immune system. Although the recipients could not reject the graft acutely after drug withdrawal, the kidney grafts and the donor-derived skin grafts had pathological findings of chronic rejection. CONCLUSIONS: The rejection response of the monkeys to an established graft after withdrawal of immunosuppression is compromised. The compromised rejection is specific and is not due to a permanent alteration of the immune system by the initial drug treatment. The allografts are not inert but have low levels of interaction with the recipient immune system.

Effect of tacrolimus (FK506) and sirolimus (rapamycin) mono- and combination therapy in prolongation of renal allograft survival in the monkey.

BACKGROUND: Our previous studies confirmed that tacrolimus (FK506) and sirolimus [rapamycin (RAPA)], in combination, are not antagonistic but are synergistic in the prolongation of heart and small bowel grafts in the rodent. The aim of this study was to confirm further the synergistic effect of combined FK506 and RAPA in the more clinically relevant model, kidney transplantation in monkeys. METHODS: A total of 60 male Vervet monkeys were randomly assigned to 10 groups (n> or =5). Monkeys with renal allografts were treated with different doses of FK506 and/or RAPA orally for 60 days. Graft survival, body weight, clinical biochemistry determinations, oral glucose tolerance test, trough levels of the two drugs, and histopathology were investigated. RESULTS: Low doses of FK506 (1 or 4 mg/kg) combined with RAPA (0.5 mg/kg) produced synergistic effect in the prolongation of renal graft survival [combination index (CI) = 0.292, 0.565]. There were no additive or synergistic drug-associated toxicities such as hyperglycemia, nephrotoxicity, and hyperlipidemia. There also was no pharmacological antagonism. CONCLUSION: Concomitant therapy of low-dose (drug-optimal) FK506 and RAPA produced a synergistic effect in the prolongation of kidney allograft survival in Vervet monkeys without additive drug-associated toxicities.

Blocking of CD44-hyaluronic acid interaction prolongs rat allograft survival.

BACKGROUND: Lymphocyte activation and infiltration into a transplanted organ is an integral component of the rejection process. Graft infiltration of lymphocytes requires adhesion of leukocytes to the endothelium, diapedesis, and transmigration. One of several proteins involved in this process is CD44, which is known to interact with endothelial hyaluronan (HA). Blockade of cell-matrix and cell-cell interactions have been used extensively for modulation of immune responses and graft rejection. Based on these observations, we evaluated the effects of blocking CD44-HA interactions in a transplantation model. METHODS: We used a low molecular weight hyaluronic acid formulation (LMWHA) for the treatment of rat renal and cardiac allograft recipients. LMWHA was administered intraperitoneally at 0.5-5 mg/kg for 5-10 days after transplantation with or without a subtherapeutic dose of cyclosporine. RESULTS: LMWHA monotherapy prolonged allograft survival significantly, but only for a few days. In combination with low-dose cyclosporine, long-term survival of allografts was observed in some of recipients. CONCLUSION: Further definition of the underlying mechanism of LMWHA therapy may provide a rationale for the development of novel, nontoxic, nonimmunogenic immunotherapies.

[Hypertrichosis and gingival hypertrophy regression in renal transplants following the substitution of cyclosporin by tacrolimus]. / Régression de l'hypertrichose et de l'hypertrophie gingivale chez des greffés rénaux suite à la substitution de la cyclosporine par le tacrolimus.

Gingival Hyperplasia (GH) and hypertrichosis (HT) are two sides effects associated with the usage of cyclosporine (CyA) but not with tacrolimus (FK 506). The aim of this study is to evaluate the efficacy and security of the conversion from CsA to FK 506 to treat those two complications. From August 1996 to May 1997, 15 patients (9 males, 6 females) aged from 23 to 63 years old (38 +/- 14, mean +/- SD) were switched from CsA to FK 506, 12 for GH, 2 for HT and one for combined presentation. FK 506 was first initiated at a dose of 0.15 mg/kg/day and then adjusted to a level target of 8 ng/ml. The conversion was done on an out patient basis at average 35 (5-83) months after transplantation. Patients were followed prospectively for 12 months. There was a significant reduction in GH in all patients within 3 months. Five out 13 patients had a complete resolution of GH within three months of conversion, 9/12 within 6 months and all by 12 months. HT resolved completely within 6 months. No rejection episode occurred and the serum creatinin remain stable over one year post conversion. Conversion from CsA to FK 506 is thus a safe and valid option to treat CsA induced GH and HT.

Immunomodulating effects of second-generation calcium channel blockers on experimental heart transplantation.

The administration of second-generation calcium channel blockers (CCBs) to counteract the adverse effects of conventional immunosuppression gains more and more acceptance. Since these newly developed molecules differ in their chemical structure and possess specific pharmacokinetic profiles, we hypothesized that exposure to clinically relevant concentrations may have a significant immunomodulatory potential. The effects of various second-generation CCBs, felodipine, amlodipine, mibefradil and clentiazem, on cardiac allograft survival were therefore evaluated. Inbred male Lewis rats were used as recipients and Brown-Norway rats as donors. After abdominal implantation of the donor heart, allograft recipients were exposed to felodipine (31 microg/kg/day), amlodipine (25 microg/kg/day), mibefradil (3 mg/kg/day) or clentiazem (2.5 mg/kg/day). Other allograft recipients were treated with low-dose cyclosporine (CsA) alone (2 mg/kg/day) or with low-dose CsA combined with amlodipine (25 microg/kg/day), mibefradil (3 mg/kg/day) or clentiazem (2.5 mg/kg/day). All drugs were given daily by gavage. Median survival time of untreated cardiac allografts was 6.5 days. When given alone, not all the second-generation CCBs elicited a positive effect: the dihydropyridines felodipine and amlodipine were ineffective (median survival time was 6.5 and 7.0 days, respectively), the T- and L-type CCB mibefradil had a significant but minor impact (median survival time = 9.0 days, p <0.0015) while the benzothiazepine clentiazem produced the most significant result (median survival time = 16.0 days, p <0.0033). Neither amlodipine nor mibefradil modified the extent of survival provided by low-dose CsA (median survival time = 9.0 days), while clentiazem had a significant positive effect. These data indicate that second-generation CCBs differ in their immunomodulatory potential. These observations of pharmacodynamic specificity appear to be related to differences in their chemical structure as well as their interaction with other sites than the calcium channel.

Mycoplasma fermentans DNA is infrequently detected in urine specimens from renal transplant recipients.

Mycoplasma fermentans is a likely causative agent of HIV-associated nephropathy. In a pilot study, M. fermentans DNA was detected with polymerase chain reaction (PCR) in urine samples from renal allograft recipients; nine (39.1%) out of 23 renal allograft recipients (most of whom had chronic allograft rejection) and none of the 20 controls, were infected with M. fermentans. A cross-sectional study was conducted to investigate the prevalence of M. fermentans in urine samples from renal allograft recipients. Midstream urine samples were centrifuged at 13,000 x g, purified with QIAamp and tested with PCR using RW004/RW005 and an internal control to screen for the presence of inhibitors. Of the 264 participants recruited, 263 completed the questionnaire (172 men, 92 women); 53 had chronic renal allograft rejection, 106 had chronic renal dysfunction without rejection, 69 had a normal renal allograft for more than 3 months and 35 had a renal allograft for less than 3 months. All urine samples yielded positive results for the internal control. Mycoplasma fermentans DNA was detected once i prospectively collected urine samples. The only individual infected with M. fermentans was also seropositive for HIV-1. This study demonstrates that M. fermentans can be at most sporadically detected in urine from patients living with a renal allograft but is not implicated in chronic rejection of allograft.

De novo-developed T cells have compromised response to existing alloantigens: using Ld-specific transgenic 2C T cells as tracers in a mouse heart transplantation model.

In this study, the phenotype, TCR signaling events, and function of T cells developed de novo during adulthood in the presence of extrathymic alloantigen were investigated. C57BL/6 mice(H-2b) were first transplanted heterotopically with BALB/c hearts (H-2d) and treated with rapamycin for 2 wk to create a tolerant status. Three weeks postoperation, the mice were whole body irradiated and transplanted with bone marrow cells from 2C mice, which are transgenic for TCR, and most of their T cells are Ld-specific CD8 cells. The 2C T cells developed de novo in the C57BL/6 mice were not able to reject the heart allograft. No clonal deletion, TCR down-regulation, or CD8 down-regulation was found in the tolerized 2C T cells. There was no characteristic phenotype of these cells in terms of CD25, ICAM-1, CD44, and MEL-14 expression. Early TCR signaling events such as intracellular calcium concentration flux, tyrosine phosphorylation, Lck and Fyn kinase activities, and Lck and Fyn protein levels in the tolerized 2C T cells were comparable to their normal counterparts, but the tolerized T cells were defective in IL-2 production and proliferation upon H-2d alloantigen stimulation in vitro. Exogenous IL-2 could not reverse the compromised proliferation. The results of this study indicate that during adulthood, the de novo-developed T cells become tolerant to extrathymic Ag without clonal deletion. These newly minted T cells are functionally defective although they are indistinguishable from normal T cells in phenotypes and in some early signaling events.

Safety and tolerability of cyclosporine and cyclosporine microemulsion during 18 months of follow-up in stable renal transplant recipients: a report of the Canadian Neoral Renal Study Group.

BACKGROUND: There has been concern that the increased drug exposure associated with treatment with cyclosporine microemulsion (CsA-ME) would lead to an increase in adverse events. METHODS: The long-term safety and tolerability of conventional cyclosporine (CsA) and CsA-ME were compared in a randomized, multicenter, pharmacoepidemiologic study involving 1097 stable renal transplant patients after 18 months of follow-up. RESULTS: No significant difference was seen in change in serum creatinine or calculated creatinine clearance between the two groups. Episodes of deterioration in renal function (change in serum creatinine > or = 20%) were categorized with the following results for CsA-ME versus CsA, respectively: acute rejection, 4.5% vs. 4.5%; chronic rejection, 8% vs. 11%; CsA nephrotoxicity, 12% vs. 7% (P=0.008); transient changes, 17% vs. 12%; other causes, 4% vs. 6%. During the first 6 months of the study, a transient increase in the incidence of gastrointestinal and neurological adverse events was seen in the CsA-ME group compared with the CsA group. Up to 18 months, patients in the CsA group reported significantly fewer hearing and vestibular disorders, but more cardiovascular problems than those in the CsA-ME group (P=0.035). CONCLUSIONS: Tolerance to CsA and CsA-ME was similar. Renal function over 18 months was not adversely affected by the increased drug exposure with CsA-ME, although there was a transient increase in nephrotoxicity. The frequency of acute and chronic rejection did not change.