Effect of Early Conversion to Everolimus Together With Prophylaxis With Valganciclovir in the Prevention of Cytomegalovirus Infection in Heart Transplant Recipients

The Third International Consensus Guidelines on the Management of Cytomegalovirus in Solid-organ Transplantation

Despite recent advances, cytomegalovirus (CMV) infections remain one of the most common complications affecting solid organ transplant recipients, conveying higher risks of complications, graft loss, morbidity, and mortality. Research in the field and development of prior consensus guidelines supported by The Transplantation Society has allowed a more standardized approach to CMV management. An international multidisciplinary panel of experts was convened to expand and revise evidence and expert opinion-based consensus guidelines on CMV management including prevention, treatment, diagnostics, immunology, drug resistance, and pediatric issues. Highlights include advances in molecular and immunologic diagnostics, improved understanding of diagnostic thresholds, optimized methods of prevention, advances in the use of novel antiviral therapies and certain immunosuppressive agents, and more savvy approaches to treatment resistant/refractory disease. The following report summarizes the updated recommendations.

The Role of mTOR Inhibitors in the Management of Viral Infections: A Review of Current Literature

Viruses are the leading cause of infections after solid organ transplant. The antiviral properties of mammalian target of rapamycin inhibitors (mTORis) have been ascribed to a variety of mechanisms and historical data have supported their use over other immunosuppressants for a myriad of viruses. Herein, we summarize the most current data to highlight the role of mTORis in the management of viral infections after solid organ transplant. The mTORis play a clear role in the management of cytomegalovirus, and have data supporting their potential use for BK virus and human herpesvirus 8-related Kaposi sarcoma. No data definitively supports mTORis for use in Epstein-Barr virus-mediated posttransplant lymphoproliferative disorder or hepatitis C virus viral replication. Although theoretically an advantageous therapy for hepatitis C virus-related liver allograft fibrosis and human immunodeficiency virus, mTORi use specifically for these indications is less attractive with modern treatments currently available. Data surrounding mTORi efficacy in preventing rejection, and their toxicity profile must be balanced with their potential antiviral effects in combination with patient-specific factors.

Early Everolimus Initiation Fails to Counteract the Cytotoxic Response Mediated by CD8+ T and NK Cells in Heart Transplant Patients

The positive long-term effects of conversion to everolimus (EVL) after heart transplantation (HT) have been evaluated in several studies. However, the timing of EVL initiation, the best way to combine it with other immunosuppressive treatments, and the impact of these combinations on the immune response are poorly understood aspects. Here, we analyzed the immune phenotype and function of HT patients (n = 56) at short and long terms (prospective and retrospective cohorts), taking into account the time of EVL initiation: early (3 months post-transplant, EVL-E group) or late (>1 year post-transplant, EVL-L group) compared with mycophenolate mofetil treatment (MMF group). We show that early EVL conversion from MMF allows the increase of cytotoxic (CD56^dim CD16⁺) NK and effector-memory (EM, CD45RA⁻ CCR7⁻) CD8⁺ T cell subsets, which show a significantly higher level of expression of cytotoxic molecules, IFN-γ production and degranulation ability under activation. NK cell expansion is accompanied by an altered balance of receptor expression, increasing the activation state, and lytic activity of those cells. Those changes are detected after as little as 1 month after EVL conversion in association with the expansion of regulatory T cells and the decrease in B cell frequency. However, no changes in the immune cells subsets were observed after late EVL initiation (EVL-L) compared with the MMF group. Our results imply that only early EVL conversion induces key changes in the post-transplant immune response, preserving an efficient anti-viral response, but simultaneously showing a limited ability to counteract the cytotoxic response to the allograft.

Role of mTOR inhibitors for the control of viral infection in solid organ transplant recipients

Appropriate post-transplant immunosuppressive regimens that avoid acute rejection, while reducing risk of viral reactivation, have been sought, but remain a chimera. Recent evidence suggesting potential regulatory and antiviral effects of mammalian target of rapamycin inhibitors (mTORi) is of great interest. Although the concept of an immunosuppressive drug with antiviral properties is not new, little effort has been made to put the evidence together to assess the management of immunosuppressive therapy in the presence of a viral infection. This review was developed to gather the evidence on antiviral activity of the mTORi against the viruses that most commonly reactivate in adult solid organ recipients: cytomegalovirus (CMV), polyomavirus, Epstein-Barr virus (EBV), human herpesvirus 8 (HHV8), and hepatitis C virus (HCV). A rapid review methodology and evaluation of quality and consistency of evidence based on the GRADE system was used. The existing literature was variable in nature, although indicating a potential advantage of mTORi in CMV, polyomavirus, and HHV8 infection, and a most doubtful relation with EBV and HCV infection. Several recommendations about the management of these infections are presented that can change certain current patterns of immunosuppression and help to improve the prognosis of the direct and indirect effects of viral infection in solid organ recipients.