Conversion to everolimus in kidney transplant recipients: to believe or not believe?

Research progress of ophthalmic preparations of immunosuppressants

Immune ophthalmopathy is a collection of autoimmune eye diseases. Immunosuppressants are drugs that can inhibit the body's immune response. Considering drug side effects such as hepatorenal toxicity and the unique structure of the eye, incorporating immunosuppressants into ophthalmic nanodrug delivery systems, such as microparticles, nanoparticles, liposomes, micelles, implants, and in situ gels, has the advantages of improving solubility, increasing bioavailability, high eye-target specificity, and reducing side effects. This study reviews recent research and applications of this aspect to provide a reference for the development of an ophthalmic drug delivery system.

An open-label randomized clinical trial to evaluate the efficacy of everolimus versus tacrolimus in triple maintenance immunosuppressive therapy for kidney transplant patients

Tacrolimus (TAC), a calcineurin inhibitor, and everolimus (EVL), an mTOR inhibitor, have been used as immunosuppressive (ISS) drugs in post-kidney transplantation therapy. The objective of this study was to compare the efficacy of EVL vs TAC in the ISS maintenance triple therapy. Ninety-seven kidney transplant patients, who received triple maintenance therapy with TAC, mycophenolate mofetil (MMF), and methyl prednisone (PRED), were evaluated. After four months of post-kidney transplant therapy, 30 patients enrolled in a randomized controlled clinical trial, in which 16 patients received TAC+MMF+PRED (cohort 1), and 14 patients switched to EVL+MMF+PRED (cohort 2). The patients were followed-up for 36 months. Two patients from cohort 1 lost their grafts after one year due to non-adherence. Two patients from cohort 2 had intolerance to mTOR inhibitors and were switched back to TAC from EVL. One case (6.25%) in cohort 1 and three cases (21.43%) in cohort 2 of acute T-cell-mediated rejection was observed. Antibody-mediated acute rejection (ABMAR) was observed in four patients (25.0%) in cohort 1, and antibody-mediated chronic rejection (ABMCR) was observed in two patients (12.50%). One patient from cohort 2 lost the graft after 15 months due to polyomavirus infection. The graft survival rate was 87.50% in cohort 1 and 92.86% in cohort 2. This clinical trial showed that the EVL+MMF+PRED triple maintenance therapy was efficacious compared with TAC during 32 months of follow-up. However, further studies are needed to confirm the efficacy of this regimen for long-term graft survival.

Preparation and study of two kinds of ophthalmic nano-preparations of everolimus

Objective: To prepare everolimus nanoformulations and increase their solubility to suit their application in the eye. Methods: The everolimus micelles was prepared by thin film dispersion method using Tween-80 (P80) and polyoxyethylene stearate (P40S) as carriers. In addition, the everolimus nanosuspension was prepared by injection method using poloxamer 407 (P407), hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA) as stabilizers. It was characterized in terms of particle size, PDI and encapsulation efficiency or drug loading. The in vitro release and in vitro rabbit scleral permeability characteristics were investigated, and the pharmacokinetics of anterior chamber drug in rabbit eyes were studied. Results: The average particle size of the micelles was (8.74 ± 0.21) nm, the encapsulation efficiency and drug loading were (90.12 ± 1.18)% and (2.14 ± 0.028)%, while the average particle size of the nanosuspension was (156.47 ± 1.10) nm, and the drug loading was (16.51 ± 0.21)%, respectively. Both in vitro release and rabbit scleral permeation models were consistent with the Higuchi equation. The pharmacokinetic experiments of aqueous humor showed that area under the curve of everolimus nanosuspension was about 3 times higher than that of micelles. Micelles could be achieved in the eye and maintained for a long time. Conclusion: The preparation of everolimus micelles or nanosuspension for eye are suitable for ocular administration and expected to be new dosage form for corneal transplantation immunological rejection or other ocular disease.

Treatment with mTOR inhibitors after liver transplantation enables a sustained increase in regulatory T-cells while preserving their suppressive capacity

BACKGROUND

The mammalian targets of rapamycin (mTOR) inhibitors (sirolimus [SRL] and everolimus [EVR]) are used after transplantation for their immunosuppressive activity. Regulatory T-cells (Tregs) play a crucial role in immune tolerance. mTOR inhibitors appear to preserve Tregs, unlike Tacrolimus (Tac).

AIM

The aim of this study was to evaluate the number and function of Tregs in liver transplant recipients before and after conversion from Tac to mTOR inhibitors.

METHODS

Fifteen patients with stable graft function where converted to SRL (n=5) or EVR (n=10). Tregs (CD4⁺ CD25⁺ FoxP3⁺ CD127^low) number and activity were analysed prospectively in blood cells using flow cytometry, and functional assay.

RESULTS

Patients of both groups displayed a sustained rise in Treg levels after introduction of mTOR inhibitors (Treg levels at 3 months: 6.45±0.38% of CD4 T-cells, vs. baseline level of 3.61±0.37%, P<0.001; mean fold increase 2.04±0.73). In SRL group, 3-month Treg levels were 6.01±0.53 vs. 3.79±0.39; P=0.037, while in EVR group they were 6.63±0.67 vs. 3.54±0.51; P=0.001. By contrast, no statistical change was observed in an unconverted Tac control group. Tregs also preserved their functional ability to suppress activated T-cells.

CONCLUSION

These results suggest that mTOR inhibitors induce a significant increase in Tregs while maintaining suppressive activity after LT.

Conversion to mammalian target of rapamycin inhibitors in kidney transplant recipients with de novo cancers

Objective:

To investigate the impact of mammalian target of rapamycin (mTOR) inhibitor conversion together with minimization of calcineurin inhibitor on allograft outcome and patient survival in kidney transplant recipients with post-transplant cancers.

Methods:

A retrospective study of all kidney transplant recipients diagnosed to have post-transplant cancers between the period 1/1/1994 and 30/6/2015. Patients were divided into 2 groups: mTOR inhibitor group and non-conversion group. Outcome included allograft function, patient survival, graft survival, acute rejection and cancer recurrence.

Results:

115 patients (56 in mTOR inhibitor group and 59 in non-conversion group) were analyzed. Median follow up was 28 months (range: 1 month – 20 years). The allograft function at 1-year remained similar between both groups. There was no significant difference in the patient survival, graft survival and rejection free survival between both groups. More patients in the non-conversion group developed recurrence of cancers than mTOR inhibitor group but statistically not significant.

Conclusions:

Use of mTOR inhibitors together with calcineurin inhibitor minimization offer a reasonable option in kidney transplant recipients who developed post-transplant cancers in view of stable renal function, low rejection rate and low cancer recurrence rate.

Renal transplantation with expanded criteria donors: Which is the optimal immunosuppression?

The growing gap between demand and supply for kidney transplants has led to renewed interest in the use of expanded criteria donor (ECD) kidneys in an effort to increase the donor pool. Although most studies of ECD kidney transplantation confirm lower allograft survival rates and, generally, worse outcomes than standard criteria donor kidneys, recipients of ECD kidneys generally have improved survival compared with wait-listed dialysis patients, thus encouraging the pursuit of this type of kidney transplantation. The relative benefits of transplantation using kidneys from ECDs are dependent on patient characteristics and the waiting time on dialysis. Because of the increased risk of poor graft function, calcineurin inhibitor (CNI)-induced nephrotoxicity, increased incidence of infections, cardiovascular risk, and malignancies, elderly recipients of an ECD kidney transplant are a special population that requires a tailored immunosuppressive regimen. Recipients of ECD kidneys often are excluded from transplant trials and, therefore, the optimal induction and maintenance immunosuppressive regimen for them is not known. Approaches are largely center specific and based upon expert opinion. Some data suggest that antithymocyte globulin might be the preferred induction agent for elderly recipients of ECD kidneys. Maintenance regimens that spare CNIs have been advocated, especially for older recipients of ECD kidneys. CNI-free regimens are not universally accepted due to occasionally high rejection rates. However, reduced CNI exposure and CNI-free regimens based on mammalian target of rapamycin inhibitors have shown acceptable outcomes in appropriately selected ECD transplant recipients.

Oedema, solid organ transplantation and mammalian target of rapamycin inhibitor/proliferation signal inhibitors (mTOR-I/PSIs)

Mammalian target of rapamycin inhibitor (mTOR-I)/proliferation signal inhibitors (PSI) including sirolimus and everolimus represent a new class of drugs increasingly used in solid-organ transplantation as alternatives to calcineurin inhibitors for patients with renal dysfunction, transplant coronary arterial vasculopathy or malignancy. The most frequently occurring mTOR-I/PSI-related adverse events are similar to those associated with other immunosuppressive therapies, but some side effects are more characteristic of proliferation signal inhibitors (e.g. lymphocele, arthralgia, oedema and hyperlipidaemia). The present paper review incidence, clinical presentation and mechanism of oedema within the clinical experience of mTOR-I/PSI in solid organ transplantation.