Contemporary immunosuppression in renal transplantation

Economic evaluations of calcineurin inhibitors in renal transplantation: a literature review

People receiving a renal transplant require long-term treatment with immunosuppressant drugs. Contemporary regimens usually include a calcineurin inhibitor (CI), either ciclosporin or tacrolimus, in conjunction with at least one other drug. The aim of this study was to review the economic literature relating to the choice of CIs in patients following renal transplantation, with the specific intention of highlighting the challenges in estimating their cost effectiveness.A systematic literature search and narrative analysis was carried out, and 12 studies of varying quality and complexity were reviewed. All of the studies compared ciclosporin, azathioprine and a corticosteroid (CAS) with tacrolimus, azathioprine and a corticosteroid (TAS) but only three also evaluated the costs and effects of other possible treatment regimens. A variety of different evaluative frameworks were employed, from single randomised controlled trial-based studies over relatively short-time periods (6 months) to more complex Bayesian modelling techniques.The studies were broadly consistent in concluding that TAS was more effective than CAS in terms of reducing the rate of acute rejection episodes. Of the studies that undertook decision modelling, all but one estimated that TAS was associated with better graft-related outcomes such as rejection-free life-years, patient-survival and QALYs. Six of the studies concluded that the healthcare costs associated with TAS were lower than those for CAS. A seventh study suggested that TAS was the least costly option if costs were considered over a relatively long time period (14 years). Only one study clearly concluded that CAS was more cost effective than TAS.Clinical evidence clearly shows that TAS is more effective than CAS in terms of reducing the incidence of acute rejection following renal transplantation. The majority of published economic evaluations suggest that TAS is also the more cost-effective option. However, the economic evaluations contained a number of methodological limitations, undermining the confidence that can be attached to their results. Future economic evaluations of the CIs, and immunosuppressants in general, should address these issues in order to produce more robust cost-effectiveness estimates. Most importantly, they should evaluate a wider range of potential treatment options.

Prolongation of allograft survival by administration of anti-CD45RB monoclonal antibody is due to alteration of CD45RBhi: CD45RBlo T-cell proportions

CD45RB monoclonal antibody (mAb) therapy is capable of prolonging allograft survival. We have previously shown that CD45RB mAb enriches the CD45RBlo T-cell population in vitro and in vivo by preferentially depleting CD45RBhi T cells. The present study assessed the importance of CD45RBhi T-cell depletion in murine cardiac allograft survival by infusion of naive CD45RB T-cell subsets. Here we show that naturally occurring CD45RBloCD4+ T cells express regulatory transcription factor Foxp3 and have regulatory function, whereas CD45RBhiCD4+ T cells express low levels of Foxp3 and have effector function. Infusion of syngeneic CD45RBhi T cells significantly reduced graft survival after depletion of CD45RBhi T cells by CD45RB mAb. Reduction of graft survival also occurred when syngeneic CD45RBhi T cells were infused into rapamycin-treated mice, whereas survival was prolonged when CD45RBlo T cells were added. This indicates that an alteration in the balance between regulatory CD45RBlo and effector CD45RBhi T cells is critical to the immunologic function of CD45RB mAb. A strategy to eliminate effector T cells with consequent enrichment of the regulatory T-cell compartment may be an important new strategy in the prevention of rejection.

Chipping into the human genome: novel insights for transplantation

High throughput, high density platforms for transcriptional, proteomic, and metabonomic analyses are opening new doors for improving our understanding of the complexity and redundancy of the immune system in the interplay of the innate and allo-immune responses in organ transplantation. New insights are being obtained into the possible discrepancies between the gold standard of tissue pathological diagnosis and clinical graft outcomes, as new transcriptional categories of transplant rejection evolve. The bystander effects of chronic immunosuppression underlying the complexities of graft dysfunction are beginning to be understood. Non-invasive mechanisms to monitor transplants, by following 'footprints' of biomarker sets that reflect the disease phenotype, are being pursued for their clinical application for direct patient care. Utilization of these same biomarker sets may also offer a unique means to titrate immunosuppression and predict specific graft dysfunction events prior to clinical decline, thus bringing in the potential to reduce patient morbidity from infection and malignancy, preserve graft integrity, and limit the progression of chronic graft injury. Bioinformatics support is integral to the unraveling of the mysteries of the human genome, proteome, and metabolome in disease and in health.

Uric acid stones following hepatic transplantation

We report the case of a 52 year old man with a history of insulin-requiring diabetes and hepatitis B with cirrhosis who received an orthotopic liver transplant. One year later he developed renal colic and was found to have a 3 mm stone at the left ureterovesical junction. Numerous other stones formed and infrared spectroscopy analysis demonstrated all to be composed of 100% uric acid. Urine collections demonstrated a low urine pH of 5.1 without hyperuricosuria. His stones were effectively prevented with potassium citrate therapy. Few incidence data are available for uric acid stone occurrence in solid organ recipients. Calcineurin inhibitors are thought to often cause hyperuricemia on the basis of decreased urate excretion. However, this effect would not be expected to cause hyperuricosuria nor uric acid stones. This class of drugs may also be associated with low urine pH, perhaps on the basis of hypoaldosteronism, but the contribution of such a syndrome to uric acid stone formation is not established.