Tacrolimus for rescue of refractory renal allograft rejection

Anti-thymocyte globulins in kidney transplantation: focus on current indications and long-term immunological side effects

Antithymocyte globulins (ATGs) are part of the immunosuppression arsenal currently used by clinicians to prevent or treat acute rejection in solid organ transplantation. ATG is a mixture of non-specific anti-lymphocyte immunoglobulins targeting not only T cell subsets but also several other immune and non-immune cells, rendering its precise immunoglobulin composition difficult to appreciate or to compare from one preparation to another. Furthermore, several mechanisms of action have been described. Taken together, this probably explains the efficacy and the side effects associated with this drug. Recent data suggest a long-term negative impact on allograft and patient outcomes, pointing out the need to better characterize the potential toxicity and the benefit-risk balance associated to this immunosuppressive therapy within large clinical trials.

Long-Term Beneficial Effect of Tacrolimus Conversion on Renal Transplant Recipients

OBJECTIVE

Acute rejection, chronic allograft nephropathy, and cyclosporine (CsA) toxicity remain serious problems for renal transplant recipients and may lead to graft loss. We retrospectively analyzed 34 patients whose biopsies revealed acute and/or chronic allograft rejection, or CsA nephrotoxicity, and who converted from CsA to tacrolimus.

PATIENTS AND METHODS

From July 1996 through September 2003, CsA was converted to tacrolimus in 34 renal transplant recipients (26 male, 8 female) with renal biopsy at our hospital. Blood pressure and serum creatinine levels were checked monthly and serum cholesterol, triglyceride, and glutamic-pyruvic transaminase (GPT) levels were checked every three months.

RESULTS

A consistently stable and better function after conversion was obtained in a significant portion (24, 71%) of patients. A statistically significant decline in serum creatinine and an improvement in the glomerular filtration rate were found at 3 m, 6 m, 12 m, 36 m, and 72 m after tacrolimus conversion. In 85.7% (12/14) of patients with acute rejection and in 35.7% (5/14) of patients with chronic allograft nephropathy (concomitant with acute rejection in 5), improved or stabilized graft function was noted. In addition, the systolic blood pressure and diastolic BP dropped significantly (P<0.05), while there was no significant change in cholesterol, triglyceride, and GPT levels.

CONCLUSION

The beneficial effect of tacrolimus conversion on patients with acute rejection, chronic allograft nephropathy, or CsA nephrotoxicity was demonstrated in long-term follow up. The improvement in both renal function and blood pressure may be of paramount importance in reducing long-term cardiovascular morbidity and mortality.

Risk factors for and management of post-transplantation cardiovascular disease

The mortality rates due to cardiovascular disease (CVD) in transplant recipients are greater than in the general population. CVD is a major cause of both graft loss and patient death in renal transplant recipients, and improving cardiovascular health in transplant recipients will presumably help to extend both patient and graft survival. Further studies are needed to better evaluate the effectiveness of risk modification on subsequent CVD morbidity and mortality. There is no reason to consider risk factors for CVD such as hyperlipidaemia, hypertension and diabetes mellitus in transplant recipients differently from in the general population. In addition, there are specific transplantation risk factors such as acute rejection episodes and the use of immunosuppressive drugs. It is obvious that several of the immunosuppressive agents used today have disadvantageous influences on risk factors for CVD such as hyperlipidaemia, hypertension and post-transplantation diabetes mellitus (PTDM), but the relative importance of immunosuppressant-induced increases in these risk factors is basically unknown. This may be a strong argument for the selective use and individual tailoring of immunosuppressive agents based upon the risk factor profile of the patient, without jeopardising the function of the graft. Hyperlipidaemia is common after transplantation, and immunosuppression with corticosteroids, cyclosporin, or sirolimus (rapamycin) causes different types of post-transplantation hyperlipidaemia. However, to date, no studies have demonstrated that lipid lowering strategies significantly reduce CVD morbidity or mortality and improve allograft survival in transplant recipients. Several studies using preventive or interventional approaches are ongoing and will be reported in the near future. Post-transplantation hypertension appears to be a major risk factor determining graft and patient survival, and immunosuppressive agents have different effects on hypertension. Controlled studies support the opinion that post-transplantation hypertension must be treated as strictly as in a population with essential hypertension, diabetes mellitus, or chronic renal failure. As increasing numbers of immunosuppressive agents become available for use, we may be in a better position to tailor immunosuppressive therapy to the individual patient, avoiding the use of diabetogenic drugs, drug combinations, or inappropriate doses in patients susceptible to PTDM. Multiple acute rejection episodes have also been demonstrated to be a risk factor for CVD - a strong argument for the use of immunosuppressive drugs to reduce acute rejection. Until we have a better understanding from ongoing landmark studies on the management of CVD, presently available therapy to reduce risk factors needs to be used together with individual tailoring of immunosuppressive therapy with the aim of reducing CVD in these patients.

Conversion from cyclosporin A to tacrolimus is safe and decreases blood pressure, cholesterol levels and TGF-beta 1 type I receptor expression

To determine whether conversion from cyclosporin A (CsA) to tacrolimus (TAC)-based immunosuppressive therapy is safe and might lead to improvement in the clinical side effect profile we studied 55 cardiac allograft recipients. Ten stable patients were electively converted (0.2-1.5 yr after transplantation; group I) and 45 patients were converted on indication (0.5-14 yr after transplantation; group II). We studied blood pressure, cholesterol level and renal function in all patients. To unravel the mechanisms by which CsA may exert its toxic effects and to evaluate whether conversion is associated with immune activation, we analyzed the transforming growth factor (TGF)-beta 1 system and intragraft interleukin (IL)-2 and IL-15 mRNA expression by real-time reverse transcription-polymerase chain reaction (RT-PCR) and quantitative flow cytometry in the selectively converted patients (group I). Conversion did not result in immune activation as no clinical, histological or molecular signs of immune activation (increased intragraft IL-2 and IL-15 messenger RNA (mRNA) expression) leading to rejection were found. It did not improve renal function neither in patient group I nor in patient group II. However, after conversion the blood pressure decreased (group I: systolic 154+/-16 vs 143+/-21 mmHg, p=0.03, diastolic: 99+/-11 vs 90+/-11, p=0.02 and group II: systolic 155+/-17 vs 142+/-14, p<0.001, diastolic: 99+/-11 vs 91+/-8 mmHg, p<0.001). Likewise, the cholesterol levels improved (group I: 6.6+/-0.5 vs 5.7+/-0.3 mmol/L, p=0.001 and group II: 7.1+/-1.7 vs 6.1+/-1.7 mmol/L, p=0.001). When patients were treated with TAC the ongoing rejections (n=4) resolved and gum hyperplasia disappeared (n=5). Conversion was associated with a two-fold lower TGF-beta 1 type I receptor expression on peripheral lymphocytes and monocytes (p=0.02 and p=0.002, respectively). Conversion from CsA to TAC results in improvement of blood pressure and cholesterol levels and does not induce immune activation. These beneficial effects were accompanied with lower TGF-beta 1 type I receptor expression.

Sirolimus rescue therapy for refractory rejection in renal transplantation

BACKGROUND

Acute renal allograft rejection episodes refractory to antilymphocyte preparations almost inevitably progress to transplantation loss. To reverse ongoing rejection processes, we administered sirolimus (RAPA) after failure of conventional immunosuppressive regimens including full courses of antilymphocyte sera.

METHODS

All 36 renal transplantation recipients reported herein displayed either Grade IIB or Grade III biopsy-proven (Banff 1993 criteria) ongoing rejection episodes despite prior treatment with pulse and/or oral recycling of steroids and at least one 14- to 21-day course of murine (OKT3) or equine (ATGAM) antilymphocyte treatment. We compared the actual 12-month outcomes of two demographically similar cohorts of patients treated for refractory rejection with RAPA (Group I; n=24) or mycophenolate mofetil (MMF; Group II; n=12) added to a baseline regimen of cyclosporine (CsA)/prednisone (Pred).

RESULTS

Rescue therapy reversed the renal dysfunction in 96% of patients in the RAPA group versus 67% in the MMF group (P=0.03) despite the fact that a greater fraction of patients in the RAPA (17 of 24) than the MMF group (6 of 12) had experienced two or more episodes of acute rejection before study entry and the fact that the recurrent bouts of acute rejection occurred within the first 6 months posttransplant in 94% of patients in the RAPA group compared with 50% (P=0.005) in the MMF group. Among the patients who were reversed successfully, the rates of rebound acute rejection were similar (4% vs. 8%). The mean serum creatinine values were slightly, although not significantly, lower among RAPA than MMF patients at 1, 3, 6, and 12 months: namely, 2.6 vs. 2.8, 2.8 vs. 3.2, 3.0 vs. 3.3, and 2.8 vs. 3.2 mg/dL, respectively. The 1-year patient and graft survival rates were similar: namely, 88% vs. 92% and 83% vs. 67% for the RAPA versus MMF groups.

CONCLUSION

RAPA is a potent immunosuppressive agent for the treatment of refractory renal allograft rejection.

Tacrolimus: a further update of its pharmacology and therapeutic use in the management of organ transplantation

Tacrolimus (FK-506) is an immunosuppressant agent that acts by a variety of different mechanisms which include inhibition of calcineurin. It is used as a therapeutic alternative to cyclosporin, and therefore represents a cornerstone of immunosuppressive therapy in organ transplant recipients. Tacrolimus is now well established for primary immunosuppression in liver and kidney transplantation, and experience with its use in other types of solid organ transplantation, including heart, lung, pancreas and intestinal, as well as its use for the prevention of graft-versus-host disease in allogeneic bone marrow transplantation (BMT), is rapidly accumulating. Large randomised nonblind multicentre studies conducted in the US and Europe in both liver and kidney transplantation showed similar patient and graft survival rates between treatment groups (although rates were numerically higher with tacrolimus- versus cyclosporin-based immunosuppression in adults with liver transplants), and a consistent statistically significant advantage for tacrolimus with respect to acute rejection rate. Chronic rejection rates were also significantly lower with tacrolimus in a large randomised liver transplantation trial, and a trend towards a lower rate of chronic rejection was noted with tacrolimus in a large multicentre renal transplantation study. In general, a similar trend in overall efficacy has been demonstrated in a number of additional clinical trials comparing tacrolimus- with cyclosporin-based immunosuppression in various types of transplantation. One notable exception is in BMT, where a large randomised trial showed significantly better 2-year patient survival with cyclosporin over tacrolimus, which was primarily attributed to patients with advanced haematological malignancies at the time of (matched sibling donor) BMT. These survival results in BMT require further elucidation. Tacrolimus has also demonstrated efficacy in various types of transplantation as rescue therapy in patients who experience persistent acute rejection (or significant adverse effect's) with cyclosporin-based therapy, whereas cyclosporin has not demonstrated a similar capacity to reverse refractory acute rejection. A corticosteroid-sparing effect has been demonstrated in several studies with tacrolimus, which may be a particularly useful consideration in children receiving transplants. The differences in the tolerability profiles of tacrolimus and cyclosporin may well be an influential factor in selecting the optimal treatment for patients undergoing organ transplantation. Although both drugs have a similar degree of nephrotoxicity, cyclosporin has a higher incidence of significant hypertension, hypercholesterolaemia, hirsutism and gingival hyperplasia, while tacrolimus has a higher incidence of diabetes mellitus, some types of neurotoxicity (e.g. tremor, paraesthesia), diarrhoea and alopecia.

CONCLUSION

Tacrolimus is an important therapeutic option for the optimal individualisation of immunosuppressive therapy in transplant recipients.

Which calcineurin inhibitor is preferred in renal transplantation: tacrolimus or cyclosporine?

Cyclosporine and tacrolimus are potent inhibitors of the calcineurin-dependent cytokine synthesis in activated lymphocytes. In renal transplant patients tacrolimus is more powerful in preventing severe and refractory rejections, even when compared with the new cyclosporine microemulsion formulation. Both drugs are equally nephrotoxic, but tacrolimus induces less hypertension and less pronounced hyperlipidaemia. Especially in some categories of patients, a higher incidence of de-novo diabetes mellitus is seen with tacrolimus therapy.