Everolimus Plus Dosage Reduction of Cyclosporine in Cardiac Transplant Recipients with Chronic Kidney Disease: A Two-Year Follow-up Study

Graft-derived Cell-free DNA as a Noninvasive Biomarker of Cardiac Allograft Rejection: A Cohort Study on Clinical Validity and Confounding Factors

BACKGROUND

Circulating graft-derived cell-free DNA (dd-cfDNA) is a new marker of cardiac allograft damage that is used for noninvasive rejection diagnostics. We performed dd-cfDNA (%) in heart transplant recipients during the first posttransplant year.

METHODS

In 87 patients, serial dd-cfDNA determination at predefined time-points was performed in 770 single samples. dd-cfDNA fraction (%) was measured using an established universal droplet digital polymerase chain reaction method, providing same-day turn-around. Rejection was diagnosed according to clinical parameters and biopsies.

RESULTS

Median dd-cfDNA (%) was high (5.36%) immediately after reperfusion and decreased to a median (interquartile range) of 0.10% (0.05%-0.24%) in clinically stable patients by postoperative day 10. Compared to dd-cfDNA (%) samples in clinically stable patients, values were higher (P < 0.001) in biopsy-proven rejection ISHLT 1R (0.42% [0.15%-0.53%]) and 2R rejection (0.84% [0.39%-0.97%]). Moreover, dd-cfDNA (%) was already significantly increased 9-30 days before biopsy-proven rejection (0.36% [0.20%-0.61%]). An as yet unknown finding was a slightly, but significantly (P < 0.0001) higher dd-cfDNA (%) value in samples of stable patients with pericardial effusions (PEs) (n = 94; 0.18% [0.07%-0.30%]) compared to samples of non-PE patients (n = 132; 0.07% [0.04%-0.17%]). Using a cutoff of 0.35%, sensitivity and specificity of dd-cfDNA for cardiac rejection were 0.76 and 0.83 (area under the curve [AUC] ROC-curve: 0.81 [95% confidence interval, 0.73-0.89]). Omitting PE samples from the control group yielded an AUC of 0.86 [95% confidence interval, 0.76-0.95]. Samples drawn <12 hours after endomyocardial biopsy showed high (0.40% [0.15%-1.21%]) dd-cfDNA values, also in ISHLT0R (0.36% [0.10%-0.60%]).

CONCLUSIONS

dd-cfDNA plasma values were significantly associated with cardiac rejection. However, PE or improper sampling (eg, shortly after biopsy) should be considered as confounders for rejection diagnoses using dd-cfDNA.

Mammalian Target of Rapamycin Inhibitors Vs Calcineurin Inhibitors in Chronic Graft Rejection After Lung Transplantation: A Systematic Review and Meta-Analysis

BACKGROUND

The number of lung transplantations has been rising constantly. However, use of this therapeutic resource is limited by several issues that are difficult to resolve, such as chronic graft rejection and complications secondary to immunosuppression.

METHODS

This systematic review compared mammalian target of rapamycin (mTOR) inhibitor immunosuppression associated with low-dose calcineurin inhibitors with isolated calcineurin inhibitor immunosuppression on the new-onset chronic rejection development and mortality 12 months after lung transplantation. Three controlled randomized clinical trials (SHITRIT, NOCTET, and 4EVERLUNG) were selected from electronic databases.

RESULTS

Meta-analysis of the data at 12 months postintervention showed that only 4EVERLUNG assessed chronic graft rejection, with a higher incidence in the control group; however, the difference was not statistically significant (P = .197). Significant data were related to an increase in the number of adverse events (P = .0064) and improved renal function (P < .0001) in the mTOR inhibitor-based scheme. The other outcomes indicated a trend toward greater risk of death and acute graft rejection with the use of mTORs.

CONCLUSIONS

The researchers suggest considering the use of mTOR inhibitors, whose greatest benefit is felt by patients with renal dysfunction, in association with the use of calcineurin inhibitors, because of the imminent risk of death among patients with renal failure.

Renal injury and recovery in pediatric patients after ventricular assist device implantation and cardiac transplant

BACKGROUND

The use of ventricular assist devices (VADs) in children with heart failure may be of particular benefit to those with accompanying renal failure, as improved renal function is seen in some, but not all recipients. We hypothesized that persistent renal dysfunction at 7 days and/or 1 month after VAD implantation would predict chronic kidney disease (CKD) 1 year after heart transplantation (HT).

METHODS

Linkage analysis of all VAD patients enrolled in both the PEDIMACS and PHTS registries between 2012 and 2016. Persistent acute kidney injury (P-AKI), defined as a serum creatinine ≥1.5× baseline, was assessed at post-implant day 7. Estimated glomerular filtration rate (eGFR) was determined at implant, 30 days thereafter, and 12 months post-HT. Pre-implant eGFR, eGFR normalization (to ≥90 mL/min/1.73 m² ), and P-AKI were used to predict post-HT CKD (eGFR <90 mL/min/1.73 m² ).

RESULTS

The mean implant eGFR was 85.4 ± 46.5 mL/min/1.73 m² . P-AKI was present in 19/188 (10%). Mean eGFR at 1 month post-VAD implant was 131.1 ± 62.1 mL/min/1.73 m² , significantly increased above baseline (P < 0.001). At 1 year post-HT (n = 133), 60 (45%) had CKD. Lower pre-implant eGFR was associated with post-HT CKD (OR 0.99, CI: 0.97-0.99, P = 0.005); P-AKI was not (OR 0.96, CI: 0.3-3.0, P = 0.9). Failure to normalize renal function 30 days after implant was highly associated with CKD at 1 year post-transplant (OR 12.5, CI 2.8-55, P = 0.003).

CONCLUSIONS

Renal function improves after VAD implantation. Lower pre-implant eGFR and failure to normalize renal function during the support period are risk factors for CKD development after HT.

The change of immunosuppressive regimen from calcineurin inhibitors to mammalian target of rapamycin (mTOR) inhibitors and its effect on malignancy following heart transplantation

Malignancy is a significant cause of mortality after organ transplantation. There is an increased rate of malignancy following heart transplantation (HTx) compared to the general population and other organ transplant recipients. Post-HTx patients with a history of malignancy are also at a higher risk of developing new malignancies or exacerbation of their existing malignancies. Mammalian target of Rapamycin inhibitors (mTORIs) are newly introduced immunosuppressive drugs with a unique mechanism of action. By changing the immunosuppressive regimen from classic drugs, especially calcineurin inhibitors (CNIs) to mTORIs, the rate of developing de novo malignancies and the relapse of former malignancies is significantly reduced. However, issues like allograft function, total surveillance of patients, and post-transplantation complications should be considered during the conversion of drug regimens utilizing CNIs to drug regimens employing mTORIs. We reviewed different post-heart transplant maintenance immunosuppressive regimens and their effect on post-HTx malignancies with a focus on mTORIs, compared safety against effectiveness, and gathered conclusions based on our review of the literature, which may lead clinicians to make a better evidence-based decision regarding post-HTx maintenance immunosuppressive drug regimens. Overall, CNI to mTORI conversion in post-HTx maintenance immunosuppressive drug regimens was associated with a reduced rate of developing malignancy in post-HTx patients. Furthermore, nephrotoxicity decreased significantly while using mTORIs in combination with lower doses of CNIs and the rejection rate was equivalent to CNI-only regimens. In conclusion, mTORI-based maintenance immunosuppressive drug regimens seem to be safe and beneficial when considering efficacy vs. adverse effects, and all-cause mortality rates are significantly lower in patients switched to mTORIs when compared to CNI recipients.

Use of sirolimus in pediatric heart transplant patients: A multi-institutional study from the Pediatric Heart Transplant Study Group

BACKGROUND

Proliferation signal inhibitors, such as sirolimus, are increasingly used in solid-organ transplantation. However, limited data exist on sirolimus-treated pediatric patients. We aimed to describe sirolimus use in pediatric heart transplant patients and test the hypothesis that sirolimus use is associated with improved outcomes.

METHODS

A retrospective review and propensity-matched analysis of the Pediatric Heart Transplant Study database was performed on patients undergoing primary heart transplantation from 2004 to 2013 with at least 1 year of follow-up comparing patients treated vs not treated with sirolimus at 1 year after transplant. The primary outcome of interest was patient survival, with secondary outcomes including cardiac allograft vasculopathy, rejection, malignancy, and renal insufficiency.

RESULTS

Between 2004 and 2013, 2,531 patients underwent transplantation. At least 1 year of follow-up was available for 2,080 patients, of whom 144 (7%) were on sirolimus at 1 year post-transplant. Sirolimus-treated and non-treated patients had similar survival in the overall cohorts and in the propensity-matched analysis. The secondary outcomes measures were also similar, including a composite end point of all outcome measures. There was a trend toward increased time to cardiac allograft vasculopathy (p = 0.09) and decreased time to infection (p = 0.05) among sirolimus-treated patients in the overall cohort (p = 0.19) but not in the propensity-matched cohort (p = 0.17).

CONCLUSIONS

Sirolimus was used in less than 10% of patients at 1 year post-transplant. Overall outcomes of sirolimus treated and non-treated patients were similar with respect to survival and major transplant adverse events. Further study of sirolimus in pediatric heart transplant patients is needed.

Chronic renal insufficiency in heart transplant recipients: risk factors and management options

Renal dysfunction after heart transplantation is a frequently observed complication, in some cases resulting in significant limitation of quality of life and reduced survival. Since the pathophysiology of renal failure (RF) is multifactorial, the current etiologic paradigm for chronic kidney disease after heart transplantation relies on the concept of calcineurin inhibitor (CNI)-related nephrotoxicity acting on a predisposed recipient. Until recently, the management of RF has been restricted to the minimization of CNI dosage and general avoidance of classic nephrotoxic risk factors, with somewhat limited success. The recent introduction of proliferation signal inhibitors (PSIs) (sirolimus and everolimus), a new class of immunosuppressive drugs lacking intrinsic nephrotoxicity, has provided a completely new alternative in this clinical setting. As clinical experience with these new drugs increases, new renal-sparing strategies are becoming available. PSIs can be used in combination with reduced doses of CNIs and even in complete CNI-free protocols. Different strategies have been devised, including de novo use to avoid acute renal toxicity in high-risk patients immediately after transplantation, or more delayed introduction in those patients developing chronic RF after prolonged CNI exposure. In this review, the main information on the clinical relevance and pathophysiology of RF after heart transplantation, as well as the currently available experience with renal-sparing immunosuppressive regimens, particularly focused on the use of PSIs, is reviewed and summarized, including the key practical points for their appropriate clinical usage.

Effect of everolimus on the immunomodulation of the human neutrophil inflammatory response and activation

The primary cause of mortality at 5 years following a cardiac transplantation is the development of atherosclerosis, termed coronary allograft vasculopathy (CAV). This pathology is characterized by diffused intimal hyperplasia and emanates from coronary arterial injuries caused by immune inflammatory cells. Neutrophils play an important role in this inflammatory process; however, their potential participation in the pathogenesis of CAV is poorly understood. Despite their essential contribution to the prevention of graft rejection, immunosuppressive drugs could have detrimental effects owing to their pro-inflammatory activities. Thus, we investigated the impact of different immunosuppressive drugs on the inflammatory response of neutrophils isolated from the blood of healthy volunteers. Under basal conditions, mammalian target of rapamycin (mTOR) inhibitors (sirolimus and everolimus) had the most potent anti-inflammatory effect, decreasing both IL-8 release (≈−80%) and vascular endothelial growth factor (VEGF) release (≈−65%) and preserving the release of the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1RA). In TNF-α-treated neutrophils, pre-incubation with everolimus provided the most potent effect, simultaneously reducing the release of both VEGF and IL-8 while doubling the release of IL-1RA. This latter effect of everolimus was maintained even when administered in combination with other immunosuppressive drugs. Sirolimus and everolimus decreased the tumor necrosis factor (TNF)-α-induced adhesion of neutrophils to human endothelial cells and human extracellular matrix. This effect was largely dependent on the ability of these compounds to alter β₂-integrin/CD18 activation. Our results suggest a potential mechanism for the beneficial effect of everolimus in the prevention of CAV in heart transplant recipients.

Everolimus in heart transplantation: an update

The evidence base relating to the use of everolimus in heart transplantation has expanded considerably in recent years, providing clinically relevant information regarding its use in clinical practice. Unless there are special considerations to take into account, all de novo heart transplant patients can be regarded as potential candidates for immunosuppression with everolimus and reduced-exposure calcineurin inhibitor therapy. Caution about the use of everolimus immediately after transplantation should be exercised in certain patients with the risk of severe proteinuria, with poor wound healing, or with uncontrolled severe hyperlipidemia. Initiation of everolimus in the early phase aftertransplant is not advisable in patients with severe pretransplant end-organ dysfunction or in patients on a left ventricular assist device beforetransplant who are at high risk of infection or of wound healing complications. The most frequent reason for introducing everolimus in maintenance heart transplant patients is to support minimization or withdrawal of calcineurin inhibitor therapy, for example, due to impaired renal function or malignancy. Due to its potential to inhibit the progression of cardiac allograft vasculopathy and to reduce cytomegalovirus infection, everolimus should be initiated as soon as possible after heart transplantation. Immediate and adequate reduction of CNI exposure is mandatory from the start of everolimus therapy.

Use of mTOR inhibitors in chronic heart transplant recipients with renal failure: calcineurin-inhibitors conversion or minimization?

BACKGROUND

In the last decade, mTOR inhibitors (mTOR-is) have become the cornerstone of the calcineurin inhibitor (CNI)-reduced/free regimens aimed to the preservation of post-transplant renal function. We compared utility and safety of the total replacement of calcineurin inhibitors with a mTOR-i with a strategy based on calcineurin inhibitor minimization and concomitant use of m-TOR-i.

METHODS

In a retrospective multi-center cohort of 394 maintenance cardiac recipients with renal failure (GFR<60 mL/min/1.73 m(2)), we compared 235 patients in whom CNI was replaced with a mTOR-i (sirolimus or everolimus) with 159 patients in whom mTOR-is were used to minimize CNIs. A propensity score analysis was carried out to balance between group differences.

RESULTS

Overall, after a median time of 2 years from mTOR-i initiation, between group differences for the evolution of renal function were not observed. In a multivariate adjusted model, improvement of renal function was limited to patients with mTOR-i usage within 5years after transplantation, particularly with the conversion strategy, and in those patients who could maintain mTOR-i therapy. Significant differences between strategies were not found for mortality, infection and mTOR-i withdrawal due to drug-related adverse events. However, conversion group tended to have a higher acute rejection incidence than the minimization group (p=0.07).

CONCLUSION

In terms of renal benefits, our results support an earlier use of mTOR-is, irrespective of the strategy. The selection of either a conversion or a CNI minimization protocol should be based on the clinical characteristics of the patients, particularly their rejection risk.

Cyclosporine immunosuppression does not prevent the production of donor-specific antibody capable of mediating allograft vasculopathy

BACKGROUND

Late cardiac graft rejection, primarily mediated by allograft vasculopathy (AV), remains a major limitation to cardiac transplantation, even in the face of significant calcineurin inhibitor (CNI) immunosuppression. The role played by alloantibody in AV is unclear. Evidence that CNI immunosuppression suppresses CD4(+) T-cell function would suggest that antibody production and effector function would be severely limited in CNI-treated patients. In this study we examine the capacity of CNI-treated animals to develop effective alloantibody that can mediate AV.

METHODS

Wild-type (WT) B6 mice were alloimmunized using donor splenocytes or a fully major histocompatibility complex-mismatched allogeneic abdominal aortic graft in the presence of CNI immunosuppression (30 or 50 mg/kg/day cyclosporine A). Anti-serum was harvested and tested using complement-dependent in vitro cytotoxicity assays. Anti-serum was passively transferred to immunodeficient RAG1(-/-) recipients of allogeneic grafts. C4d deposition was quantified in the allografts from WT recipients.

RESULTS

CNI immunosuppression did not prevent the development of alloantibody in response to either immunization method (p < 0.05). Passive transfer of anti-serum generated AV lesions in immunodeficient graft recipients and mediated complement-dependent destruction of donor cells (p < 0.05). C4d deposition was localized to the media of grafts of CNI treated animals.

CONCLUSIONS

CNI therapy does not prevent the production of alloantibody with the capacity to mediate AV. C4d deposition in the media suggests a role for medial smooth muscle cell loss in antibody-mediated AV lesion development in our model.

Efficacy and safety of low-dose everolimus as maintenance immunosuppression in cardiac transplant recipients

For cardiac transplant (CTx) recipients, the recommended everolimus (EVL) dose is 0.75 mg bid or 1.5 mg bid and the target trough blood level is 3–8 μg/L. We studied a cohort of 56 CTx patients with chronic kidney disease receiving 0.75 mg bid EVL to maintain blood levels of 5–8 ug/L (designated RD group) and a cohort of 51 CTx patients with chronic kidney disease receiving 0.5 mg bid to maintain blood levels of 3–5 ug/L (designated LD group). The primary endpoint was a composite of death, rejection and premature EVL discontinuation up to 1 year after introduction of EVL. The primary endpoint was reached by 32% of patients in the LD group and by 41.1% of patients in the RD group (P = 0.361). Biochemical safety parameters were comparable in both groups. Our results indicate that low-dose EVL may be as effective and safe as regular dose EVL.