Outcomes following de novo CNI-free immunosuppression after heart transplantation: a single-center experience

Small-Molecule Protein Kinases Inhibitors and the Risk of Fungal Infections

Purpose of Review

This review discusses fungal infections associated with licenced small-molecule protein kinase inhibitors. For each major drug class, the mechanism of action and targeted pathways and the impact on host defence against fungi are described.

Recent Findings

Protein kinase inhibitors are successfully used in the treatment of malignancies and immune-mediated diseases, targeting signalling pathways for a broad spectrum of cytokines and growth-stimuli. These agents predispose to fungal infections by the suppression of integral components of the adaptive and innate immune response.

Summary

The greatest risk of fungal infections is seen with bruton tyrosine kinase inhibitors, e.g. ibrutinib. Infections are also reported with agents that target mTOR, Janus kinase and break point cluster (Bcr) gene–Abelson (Abl) tyrosine kinase (BCR-ABL). The type of fungal infection fits mechanistically with the specific pathway targeted. Infections are often disseminated and present soon after the initiation of therapy. The pharmacokinetic profile, possibility of off-target kinase inhibition, and underlying disease pathology contribute to infection risk.

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.

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.

Postoperative care of the transplanted patient

The successful delivery of optimal peri-operative care to pediatric heart transplant recipients is a vital determinant of their overall outcomes. The practitioner caring for these patients must be familiar with and treat multiple simultaneous issues in a patient who may have been critically ill preoperatively. In addition to the complexities involved in treating any child following cardiac surgery, caretakers of newly transplanted patients encounter multiple transplant-specific issues. This chapter details peri-operative management strategies, frequently encountered early morbidities, initiation of immunosuppression including induction, and short-term outcomes.

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.

Calcineurin inhibitor-free immunosuppression using everolimus (Certican) after heart transplantation: 2 years' follow-up from the University Hospital Münster

BACKGROUND

Everolimus is a proliferation-signal inhibitor which was introduced for heart transplant recipients in 2004. To date, there are only sparse data about long-term calcineurin inhibitor (CNI)-free immunosuppression using everolimus.

METHODS

After heart transplantation, patients receiving everolimus were consecutively enrolled. Reasons for switching to everolimus were side effects of CNI immunosuppression, such as deterioration of kidney function and recurrent rejection episodes. All 60 patients underwent standardized switching protocols, 42 patients completed 24-month follow-up. Blood was sampled for lipid status, renal function, routine controls, and levels of immunosuppressive agents. On days 0, 14, and 28, and then every 3 months, echocardiography and physical examination were performed.

RESULTS

After switching to everolimus, most patients recovered from the side effects. Renal function improved significantly after 24 months (creatinine, 2.1 ± 0.6 vs 1.8 ± 1 mg/dL; P < .001; creatinine clearance, 41.8 ± 22 vs 48.6 ± 21.8 mL/min; P < .001). Median blood pressure increased from 120.0/75.0 mm Hg at baseline to 123.8/80.0 mm Hg at month 24 (P values .008 and .003 for systolic and diastolic pressures, respectively). Tremor, peripheral edema, hirsutism, and gingival hyperplasia markedly improved. Levels of interleukin-6 were stable between baseline and 24-month levels. Temporary adverse events occurred in 8 patients [13.3%: interstitial pneumonia (n = 2), skin disorders (n = 2); reactivated hepatitis B (n = 1), and fever of unknown origin (n = 3)].

CONCLUSION

CNI-free immunosuppression using everolimus is safe, with excellent efficacy in maintenance of heart transplant recipients. Arterial hypertension and renal function significantly improved. CNI-induced side effects, such as tremor, peripheral edema, hirsutism, and gingival hyperplasia, markedly improved in most patients.

Prospective study of everolimus with calcineurin inhibitor-free immunosuppression in maintenance heart transplant patients: results at 2 years

BACKGROUND

Few studies have examined everolimus therapy with calcineurin inhibitor (CNI) withdrawal in maintenance heart transplant patients.

METHODS

In a prospective, single-arm, single-center study, CNI-treated heart transplant patients were converted to everolimus and were followed up for 24 months. The primary endpoints were kidney function and arterial hypertension at 12 and 24 months after conversion.

RESULTS

Fifty-eight patients were recruited (mean time posttransplant 5.6±3.7 years), 55 of whom (91.7%) had renal impairment. Mean creatinine clearance increased from 43.6±21.1 mL/min to 49.5±21.2 mL/min at month 24 (P=0.02). Median blood pressure increased from 120/80 mm Hg at baseline to 122.5/80 mm Hg (P=0.008 and 0.006 for systolic and diastolic pressure, respectively). Lipid parameters did not change significantly over the 24-month follow-up. Early resolution of most non-renal CNI-related adverse events was sustained. CNI therapy was re-introduced at a mean of 309 days (range, 31-684 days) in eight patients after month 6 due to adverse events (n=13) or withdrawal of consent (n=2). No significant changes in cardiac function parameters were observed.

CONCLUSIONS

CNI-free immunosuppression with everolimus is an effective and safe option in selected heart transplant maintenance patients. Most adverse effects under everolimus occurred early after conversion and generally resolved without intervention within a few weeks. Refining selection criteria may reduce the need to re-introduce CNI therapy.

Heart transplantation

PURPOSE OF REVIEW

This paper briefly and subjectively reviews a number of the modest or tentative, but noteworthy, advances in heart transplantation that have been made during the past 18 months or so.

RECENT FINDINGS

The advances reviewed concern the selection of recipients, the management of the heart transplantation waiting list, the management of donors, post-heart transplant monitoring of immunological status, the early diagnosis of rejection, the role of mammalian target of rapamycine inhibitors and induction agents, and the definition and grading of cardiac allograft vasculopathy.

SUMMARY

The findings reviewed indicate progress in the clarification of issues that were in most cases already being investigated. Further studies will in general be needed before corresponding measures are adopted in clinical practice.

Indications, tolerance and complications of a sirolimus and calcineurin inhibitor immunosuppression regimen: intermediate experience in pediatric heart transplantation recipients

Although SRL has been used in adults, few studies are reported in pediatric Htx recipients. Retrospective chart review of all Htx patients on SRL. We evaluated Cr at Htx and years 1, 3, 5, 7, 9, 11, 13, and 15 post-Htx. GFR was calculated (Schwartz). BMI, Hgb, lipid profiles, and complications were compared to 59 controls, and a matched case-control group used to compare GFR to SRL cohort. Twenty-one patients were converted to SRL 1-2 mg/day (target 4-8 ng/mL) and analyzed. Reasons for conversion: re-transplantation/TCAD (8), renal (7), rejection (5), other (1). Cr was higher (p = 0.004) and GFR lower (p = 0.025) in SRL group than controls at Htx. Patients began SRL a median of 3.6 yr (0.1-16.2) post-Htx at 15.2 yr of age (4.4-24.4), with follow-up 0.5-4.6 yr. SRL was well tolerated with no increase in hyperlipidemia, rejection or mortality. None required SRL discontinuation. SRL was well tolerated in pediatric Htx patients. Kidney function remained stable; subjects had no increase in mortality, rejection or PTLD. Multicenter studies using renal sparing protocols are needed to determine whether SRL should be used routinely in children.

Impact of different long-term maintenance immunosuppressive therapy strategies on patients' outcome after heart transplantation

The introduction of cyclosporine in the early 1980s meant a decisive improvement in post-transplant outcomes for all solid-organ transplants and, in particular, it allowed heart transplantation to emerge as a viable therapeutic option for patients with end-stage cardiac failure. Many factors, including recipient and donor selection, organ preservation and the technical aspects of the transplant itself, influence post-operative outcomes following heart transplantation but the continued need to treat the recipient's immune response plays a key role in determining long-term outcomes. Thereby interactions between immunosuppressive drugs used in different combinations play an important role in patients' outcome. After more than two decades, significant controversy still exists as to the best immunosuppressive regimen for long-term maintenance. During the 1990s and 2000s, newer immunosuppressive medications, specifically, tacrolimus, mycophenolate mofetil, sirolimus, everolimus and the IL-2 receptor blockers (daclizumab and basiliximab), were introduced that allow the clinician several options to try to minimize side effects and maximize the desired therapeutic effects. The side effects involve direct organ toxicity (e.g. renal and hepatic dysfunction), metabolic disturbances, (e.g. diabetes, hyperlipidemia and hypertension), neurotoxicity, and several other significant adverse events, such as cholestasis and myelosuppression. Newer immunosuppressive drugs can impair wound healing, induce lung toxicity and produce various cytopenic states. Steroids continue to plague patients with their well-known side effects. This article reviews the current data on the benefits and risks of the various therapeutic regimens available, which are analyzed under three main themes: calcineurin inhibitor based therapies, calcineurin minimization protocols and calcineurin free regimens.