The role of newer monoclonal antibodies in renal transplantation

Sirolimus as renal and immunological rescue agent in pediatric liver transplant recipients

CNI have improved the outcome of LT. However, their inherent potential to nephrotoxic and sometimes-inadequate immunosuppressive effect has lead to the usage of newer drugs like SRL. Aim of this study was to review children who received SRL. Thirty-seven (20 women) children post-LT, median age 10.4 yr (0.8-17.4) with a minimum follow-up of six months comprised the study group. Indications for SRL were biopsy-proven resistant acute allograft rejection (n = 12), early CR (n = 12), and CNI-induced nephropathy with MMF intolerance (n = 11). In two patients, the indication was the recurrence of BSEP disease in the allograft. In patients with acute rejection, AST normalized in 10/12 patients. In patients with CR, AST normalized in 6/12 patients. Those with renal impairment showed improvement in their creatinine levels from a mean baseline of 99-56.7 μm (p = 0.03) and their mean cystatin C was 1.02 after SRL. Side effects leading to discontinuation of SRL were seen in three patients. SRL was effective in rescuing patients with acute and chronic allograft rejection and improving renal function in CNI-induced nephropathy group.

Immunosuppression in pediatric liver transplantation: are little people different?

1. Children differ from adults in the pharmacokinetics and dynamics of most immunosuppressive agents. 2. A lack of clinical trials continues to be an issue for newer agents. 3. On the basis of clinical case series, mycophenolate mofetil and sirolimus are increasingly being used as renal-sparing agents. 4. In comparison with adults, the recurrence of both viral hepatitis and hepatocellular carcinoma is less of an issue in children. 5. Particular attention should be paid to complete age-appropriate immunization to avoid vaccine-preventable diseases. 6. Paying special attention to adherence and the transition to adult services is essential for minimizing graft loss.

The role of basiliximab induction therapy in organ transplantation

Basiliximab is a chimeric monoclonal antibody that selectively binds to the alpha-subunit (CD25) of IL-2 receptors on the surface of activated T lymphocytes, and is a highly effective prophylaxis agent against rejection in organ transplant recipients. Its pharmacokinetic profile is characterized by a biphasic and slow clearance with long terminal half-life and a volume of distribution within the central compartment and outside the circulatory system. Basiliximab induction demonstrated an excellent safety profile, with no increase in the incidence of malignancy, infections or death. It has also been used effectively in high-risk recipients, steroid-sparing and steroid-minimization protocols, and in post-transplant patients with renal dysfunction who would benefit from delayed introduction of calcineurin inhibitors. Basiliximab induction therapy given at days 0 and 4 after transplantation appears to be safe and cost-effective for immunoprophylaxis in solid organ transplant recipients, specifically in kidney and liver transplantation, when given in conjunction with dual or triple immunosuppressive therapy.

Daclizumab is associated with decreased rejection and improved patient survival in renal transplant recipients

The present study investigated the safety of induction therapy with daclizumab (compared with no induction treatment), in adult renal transplant patients reported to the Scientific Registry of Transplant Recipients (SRTR) database between January 1, 1998 and July 27, 2003. Patients who were discharged from the hospital on mycophenolate mofetil, azathioprine, or sirolimus were divided into two groups: induction treatment with daclizumab (n = 8203) and no induction treatment (n = 25,368). Patient survival, death due to infection and death due to malignancy were evaluated at 1 and 3 yr post-transplantation. Rejection and graft survival were also examined. Kaplan-Meier and Cox regression models were used to evaluate outcomes. No significant differences were found between patients treated with daclizumab compared with patients who received no induction therapy for death due to infection or malignancy at 1 and 3 yr post-transplantation. Patients treated with daclizumab (compared with no induction treatment) had statistically significantly better survival rates at 1 (96.9% vs. 96.2%, p = 0.003) and 3 yr (92.4% vs. 91.4%, p = 0.004) although absolute differences were minimal. This was confirmed in the multivariable Cox regression analysis for patient death at 1 (HR = 0.77, p < 0.001) and 3 yr (HR = 0.83, p = 0.001) post-transplantation. Patients treated with daclizumab compared to no induction had lower rejection rates at 1 (13.1% vs. 17.3%, p < 0.001) and 3 yr post-transplantation (16.7% vs. 21.3%, p < 0.001). Cox regression confirmed a decreased risk for rejection at 1 (HR = 0.74, p < 0.001) and 3 yr (HR = 0.75, p < 0.001). Treatment with daclizumab was associated with reduced risk for graft loss at 1 (HR = 0.82, p < 0.001) and 3 years (HR = 0.86, p < 0.001). In conclusion, daclizumab was associated with a significantly reduced risk for rejection and graft loss compared with no induction treatment, and improved patient survival. In addition, daclizumab was not associated with an increase in risk of death due to infection or malignancy, when compared with no induction therapy. These findings demonstrate the short and long-term safety and efficacy of daclizumab in patients transplanted between January 1998 and July 2003.

Immunosuppression: towards a logical approach in liver transplantation

Over the last two decades there has been a significant increase in the number and types of immunosuppressive agents that have been available to clinicians. The protocols for immunosuppression used in liver transplantation have been derived historically from those in renal transplantation. During the last decade there has been a shift in the use of immunosuppression, with the introduction of interleukin (IL)-2 receptor antagonists in place of anti-lymphocyte preparations, substitution of tacrolimus for cyclosporin and mycophenolate for azathioprine. The use of corticosteroids has been reduced. For a variety of reasons, these changes have not always been made on the basis of properly randomized studies. The place of newer agents, such as sirolimus and leflunomide derivatives and of the microbiological agents, is unclear. In this review, we outline briefly the mechanism of action of drugs and suggest possible approaches to the management of the liver allograft recipient, suggesting how treatment could be adjusted according to the indication for transplantation as well as the individual's comorbidities.

New insights into the interactions between T-cell costimulatory blockade and conventional immunosuppressive drugs

OBJECTIVE

To determine the precise in vivo interaction between T-cell costimulatory blockade and conventional immunosuppression in transplantation.

SUMMARY BACKGROUND DATA

Blocking B7 or CD154 T-cell costimulatory activation pathways prevents allograft rejection in small and large animal transplant models and is considered a promising strategy for clinical organ transplantation.

METHODS

A fully MHC-mismatched vascularized mouse cardiac allograft model was used to test the interactions between anti-CD154 or CTLA4Ig monotherapy and conventional immunosuppressive drugs in promoting long-term graft acceptance. The frequency of alloreactive T cell was measured by ELISPOT. Chronic rejection was examined by histology.

RESULTS

Cyclosporine, tacrolimus, and anti-IL-2R monoclonal antibody therapy abrogated the effect of a single-dose protocol of anti-CD154 therapy. In contrast, rapamycin acted synergistically with anti-CD154 therapy in promoting long-term allograft survival. The addition of calcineurin inhibitors did not abolish this synergistic effect. Intense CD154-CD40 blockade by a multiple-dose schedule of anti-CD154 resulted in long-term graft survival and profound alloreactive T-cell unresponsiveness and overcame the opposite effects of calcineurin inhibitors. CTLA4Ig induced long-term graft survival, and the effect was not affected by the concomitant use of any immunosuppressive drugs.

CONCLUSIONS

The widespread view that calcineurin inhibitors abrogate the effects of T-cell costimulatory blockade should be revisited. Sufficient costimulatory blockade and synergy induced by CD154 blockade and rapamycin promote allograft tolerance and prevent chronic rejection.

New developments in immunosuppressive therapy in renal transplantation

The introduction of new immunosuppressive agents and protocols has improved outcomes for renal transplant recipients by decreasing the risk of rejection and by increasing the function and lifespan of the allograft. This article reviews the major changes in the combinations of therapies used: calcineurin inhibitors, target of rapamycin inhibitors, mycophenolate mofetil, non-depleting monoclonal versus depleting monoclonal and polyclonal antibodies for induction and increasing emphasis on protocols for reduction or avoidance of steroids and calcineurin inhibitors. The new agents with novel immunological targets such as anti-CD40 ligand, LEA29Y, FTY720, anti-CD20 (rituximab, Rituxan, Mabthera) and anti-CH52 (alemtuzumab, Campath), which are under development but have yet to survive the rigors of clinical trials are also discussed. In the presence of low early rejection rates, immunosuppressive therapy is setting new goals such as better graft function (glomerular filtration rates), reduction in adverse effects such as hypertension, hyperlipidaemia and drug toxicity and, above all, the prevention of late graft deterioration.