Multidisciplinary insights on clinical guidance for the use of proliferation signal inhibitors in heart transplantation

Pharmacokinetic optimization of immunosuppressive therapy in thoracic transplantation: part I

Although immunosuppressive treatments and therapeutic drug monitoring (TDM) have significantly contributed to the increased success of thoracic transplantation, there is currently no consensus on the best immunosuppressive strategies. Maintenance therapy typically consists of a triple-drug regimen including corticosteroids, a calcineurin inhibitor (ciclosporin or tacrolimus) and either a purine synthesis antagonist (mycophenolate mofetil or azathioprine) or a mammalian target of rapamycin inhibitor (sirolimus or everolimus). The incidence of acute and chronic rejection and of mortality after thoracic transplantation is still high compared with other types of solid organ transplantation. The high allogenicity and immunogenicity of the lungs justify the use of higher doses of immunosuppressants, putting lung transplant recipients at a higher risk of drug-induced toxicities. All immunosuppressants are characterized by large intra- and interindividual variability of their pharmacokinetics and by a narrow therapeutic index. It is essential to know their pharmacokinetic properties and to use them for treatment individualization through TDM in order to improve the treatment outcome. Unlike the kidneys and the liver, the heart and the lungs are not directly involved in drug metabolism and elimination, which may be the cause of pharmacokinetic differences between patients from all of these transplant groups. TDM is mandatory for most immunosuppressants and has become an integral part of immunosuppressive drug therapy. It is usually based on trough concentration (C(0)) monitoring, but other TDM tools include the area under the concentration-time curve (AUC) over the (12-hour) dosage interval or the AUC over the first 4 hours post-dose, as well as other single concentration-time points such as the concentration at 2 hours. Given the peculiarities of thoracic transplantation, a review of the pharmacokinetics and TDM of the main immunosuppressants used in thoracic transplantation is presented in this article. Even more so than in other solid organ transplant populations, their pharmacokinetics are characterized by wide intra- and interindividual variability in thoracic transplant recipients. The pharmacokinetics of ciclosporin in heart and lung transplant recipients have been explored in a number of studies, but less is known about the pharmacokinetics of mycophenolate mofetil and tacrolimus in these populations, and there are hardly any studies on the pharmacokinetics of sirolimus and everolimus. Given the increased use of these molecules in thoracic transplant recipients, their pharmacokinetics deserve to be explored in depth. There are very few data, some of which are conflicting, on the practices and outcomes of TDM of immunosuppressants after thoracic transplantation. The development of sophisticated TDM tools dedicated to thoracic transplantation are awaited in order to accurately evaluate the patients' exposure to drugs in general and, in particular, to immunosuppressants. Finally, large cohort TDM studies need to be conducted in thoracic transplant patients in order to identify the most predictive exposure indices and their target values, and to validate the clinical usefulness of improved TDM in these conditions. In part I of the article, we review the pharmacokinetics and TDM of calcineurin inhibitors. In part II, we will review the pharmacokinetics and TDM of mycophenolate and mammalian target of rapamycin inhibitors, and provide an overall discussion along with perspectives.

Lower incidence of cytomegalovirus infection with everolimus versus mycophenolate mofetil in de novo cardiac transplant recipients: a randomized, multicenter study

Cytomegalovirus (CMV) is a major cause of infectious complications following cardiac transplantation, severely affecting short- and long-term outcomes. A 12-month, multicenter, randomized, open-label study in de novo cardiac transplant patients was undertaken to compare the efficacy, renal function, and safety of everolimus plus reduced cyclosporine versus mycophenolate mofetil (MMF) plus standard cyclosporine (ClinicalTrials.gov NCT00150046). CMV-specific data was prospectively collected on infections, laboratory evidence, CMV syndrome, and CMV disease. In total, 176 patients were randomized (everolimus 92; MMF 84). Use of CMV prophylaxis was similar between groups (everolimus 20.8%; MMF 24.0%). Patients in the everolimus arm had a significantly lower incidence of any CMV event (8.8% versus 32.5% with MMF, P<0.001), CMV infection as an adverse event (4.4% versus 16.9%, P=0.011), laboratory evidence of CMV (antigenemia 7.7% versus 27.7%, P<0.001; polymerase chain reaction assay 2.2% versus 12.0%, P=0.015), and CMV syndrome (1.1% versus 8.4%, P=0.028). In the donor (D)+/recipient (R)+and D-/R+ subgroups, even after adjusting for use of prophylaxis, the CMV event rate remained significantly lower with everolimus than with MMF (P=0.0015 and P=0.0381, respectively). In conclusion, de novo cardiac transplant recipients experienced lower rates of CMV infection, CMV syndrome, or organ involvement on an everolimus-based immunosuppressant regimen compared with MMF.

Incidence of delayed graft function and wound healing complications after deceased-donor kidney transplantation is not affected by de novo everolimus

BACKGROUND

Concerns about delayed graft function (DGF) and wound healing complications with sirolimus has led to suggestions that everolimus introduction could be delayed after transplantation.

METHODS

In a prospective, multicenter, open-label study, deceased-donor kidney transplant recipients at protocol-specified risk of DGF (defined as > or =1 dialysis session during the first week posttransplant excluding day 1) were randomized to start everolimus therapy on day 1 posttransplant (immediate everolimus [IE]), or from week 5 (delayed everolimus [DE]) with mycophenolic acid until everolimus was initiated. All patients received anti-interleukin-2 receptor antibodies, cyclosporine A, and corticosteroids. A planned 3-month analysis from this 12-month study is presented here.

RESULTS

One hundred and thirty-nine patients were randomized (IE 65, DE 74). The primary composite endpoint: biopsy-proven acute rejection, graft loss, death, DGF, wound healing events, or lost to follow-up at month 3, occurred in 36 IE patients (55.4%) and 47 DE patients (63.5%, P=0.387). The incidence of DGF was similar between groups (IE 24.6%, DE 24.3%; n.s.). Wound healing events of any type occurred in 40.0% and 41.9% of IE and DE patients (n.s.); events relating to initial transplant surgery occurred in 36.9% IE patients and 37.8% DE patients (n.s.), most of which were fluid collections. Study drug was discontinued due to adverse events or graft loss in 13 IE (20.0%) and 17 DE patients (23.0%).

CONCLUSIONS

Findings from this randomized, multicenter trial indicate that kidney function recovery, wound healing, efficacy, and tolerance are similar at 3 months posttransplant with immediate or DE in patients at protocol-specified risk of DGF.

Progression of renal dysfunction in cardiac transplantation after the introduction of everolimus in the immunosuppressive regime

The aim of this study was to analyze, in heart transplant patients, if renal function improvement after cyclosporine replacement by everolimus persists at the middle term and its predictors. We studied prospectively 56 patients in whom conversion was consecutively made. Forty-five patients completed the follow-up period. Significant improvement was observed at 6 and 12 months in plasma creatinine levels (1.92+/-0.7 vs. 1.67+/-0.6 and 1.69+/-0.6 mg/dL; P=0.047) and glomerular filtration rate (43.9+/-17 vs. 52.5+/-23 and 51.3+/-22.3 mL/min; P=0.004). Glomerular filtration rate increased in 32 patients (71%). Baseline characteristics comparison showed a lower percentage of patients with smoking history and new onset diabetes in responders group, but only previous smoking was shown as independent factor (Exp B: 0.083; 95% confidence interval: 0.010-0.793; P=0.024). No differences regarding age, gender, body mass index, disease leading to transplantation, time between transplantation and replacement, cardiovascular risk factors, lipid levels, and hematologic parameters were found.

The use of proliferation signal inhibitors in the prevention and treatment of allograft vasculopathy in heart transplantation

Cardiac allograft vasculopathy (CAV) currently represents one of the most important causes of long-term morbidity and mortality in the heart transplant population. In well-designed studies with de novo patients, the use of proliferation signal inhibitors (PSIs; everolimus and sirolimus) has been shown to significantly prevent the intimal growth of graft coronary arteries in comparison to other immunosuppressive regimens, reducing the incidence of vasculopathy at 12 and 24 months. In addition, conversion to PSIs in maintenance patients with established CAV has also shown promising results in the reduction of the progression of the disease and its clinical consequences. For these reasons the interest shown by various transplantation units in the potential role of PSIs in this field is growing. The aim of the present article is to review the information obtained to date on the use of PSIs in heart transplant recipients, both in the prevention and the treatment of CAV. The principal published recommendations on the introduction and appropriate management of these drugs in clinical practice are also collected, as well as certain recommendations given by the authors based on their experience.