Incidence of cytomegalovirus infection in seropositive kidney transplant recipients treated with everolimus: A randomized, open-label, multicenter phase 4 trial

Persisting Gaps in Cytomegalovirus Prevention and Management After Solid Organ Transplantation in a Resource-Limited Setting

BACKGROUND

Cytomegalovirus (CMV) infection remains among the leading complications after solid organ transplantation (SOT). Large international surveys mainly focused on high-income countries, detected considerable variability in the management of this infection after SOT. Limited data are available from resource-limited settings.

METHODS

A questionnaire-based cross-sectional study was performed. All transplant programs (TP) registered at the Brazilian Organ Transplantation Society (ABTO) were invited to participate.

RESULTS

Sixty-one TP participated in the study. Of these, 59 (97%) reported using at least 1 preventive strategy (prophylaxis or preemptive therapy [PET]). Prophylaxis was reported by only 39 (64%). PET was used by 52 (85%), predominantly for R+ recipients (n = 42/61; 70%). CMV monitoring was performed weekly in only 22 of 52 (42%) TP. This was significantly more common in TP reporting turnaround times ≤72 h for quantitative nuclear acid amplification tests (p < 0.001). Intravenous (IV) ganciclovir was the predominant drug chosen for prophylaxis (21/39 TP; 54%) and for PET (44/52 TP; 77%). Lack of regular access to valganciclovir was significantly associated with the choice of IV ganciclovir for prophylaxis and PET (p = 0.002 for both comparisons). Only 8 (13%) TP had access to molecular diagnostic tests for ganciclovir resistance, and 14 (23%) had access to effective therapy for highly resistant infections.

CONCLUSION

These results suggest that strategies to improve the management of CMV after SOT in such a resource-limited setting are needed and should include not only targeted educational programs but also initiatives to tackle economic and structural barriers.

Belatacept-related cytomegalovirus infection: Advocacy for tailored immunosuppression based on individual assessment of immune fitness

Belatacept, a fusion protein combining cytotoxic T-lymphocyte antigen-4 (CTLA-4) and the Fc region of human IgG1, is increasingly used as a calcineurin inhibitor-sparing regimen in patients with chronic graft dysfunction. Older kidney transplant recipients, particularly from expanded criteria donors, may be switched to belatacept due to poor renal recovery. However, late-onset cytomegalovirus (CMV) reactivation is increasingly reported with this treatment, especially in older patients with graft dysfunction. This suggests a progressive loss of CMV-specific T cell response, potentially driven by T cell exhaustion. Contributing factors include preexisting T cell dysfunction, increased viral antigen exposure, and interference in the PD-L1/PD-1 pathway by belatacept. mTOR inhibitors have shown efficacy in preventing CMV reactivation by reinvigorating CMV-specific T cells. These findings support combining belatacept with mTOR inhibitors in high-risk CMV-seropositive recipients and emphasize the need for personalized immune assessments to guide immunosuppressive strategies.

Insights from the BKEVER Trial comparing everolimus versus mycophenolate mofetil for BK Polyomavirus infection in kidney transplant recipients

The MTOR inhibitors have demonstrated antiviral properties, and prior non-randomized studies have suggested they may have a suppressive effect on BKPyV replication. Here, in this randomized, multicenter, controlled trial (BKEVER study), we sought to evaluate the impact of everolimus (EVR) in facilitating the clearance of BKPyV compared to simply reducing immunosuppression among kidney transplant recipients (KTRs). All together, 130 KTRs presenting with BKPyV DNAemia were randomized 1:1 into two groups. The EVR group, in which mycophenolate mofetil (MMF) was replaced by EVR along with a decrease in calcineurin inhibitor trough levels and secondly the MMF group, in which the MMF dose was decreased by half along with a similar lowering of calcineurin inhibitor levels. The primary endpoint was the proportion of patients achieving viral clearance at six months. Secondary endpoints included the kinetics of BKPyV replication over time, the incidence of BKPyV-associated nephropathy, kidney graft function, the incidence of kidney graft rejection, and medication tolerability over two years. Significantly, BKPyV clearance was achieved in 55.7% of patients in the EVR group compared to 81.3% of patients in the MMF group at six months. The reduction in BKPyV DNA load was significantly more rapid in the MMF group. Calcineurin inhibitor trough levels were within expected target ranges and did not differ meaningfully between the two groups from randomization through month six. Two grafts were lost, and four patients died. Eleven patients in the EVR group and six patients in the MMF group developed biopsy-proven BKPyV nephropathy. Thus, in KTRs with BKPyV DNAemia, replacing MMF with EVR along with lowering calcineurin inhibitor levels did not lead to more frequent or faster clearance of BKPyV.

Diagnostic Performance of Two Different Techniques to Quantify CMV-Specific Cell-Mediated Immunity in Intermediate-Risk Seropositive Kidney Transplant Recipients

BACKGROUND

Kidney transplant (KT) recipients at intermediate risk for cytomegalovirus (CMV) infection constitute a potential target for individualized prevention strategies informed by the CMV-specific cell-mediated immunity (CMV-CMI). The optimal method for the functional assessment of CMV-CMI in this group remains unclear.

METHODS

We included 74 CMV-seropositive KT recipients that did not receive T-cell-depleting induction and were managed by preemptive therapy. CMV-CMI was monitored at baseline and months 1, 3, 6, and 12 by intracellular cytokine staining (ICS) and a interferon (IFN)-γ-release assay (QuantiFERON-CMV [QTF-CMV]). Both methods were compared for discriminative capacity (areas under the receiving operating characteristic curve [auROCs]) and diagnostic accuracy to predict protection against high-level (≥1000 IU/mL) CMV DNAemia and/or disease.

RESULTS

Eighteen patients (24.3%) experienced high-level CMV DNAemia or disease. There were no significant differences in the discriminative capacity to predict protection of CMV-specific CD8+ (auROC: 0.719) and CD4+ T-cell counts (auROC: 0.664) enumerated by ICS and IFN-γ production measured by QTF-CMV (auROC: 0.666). Optimal cutoff values of ≥9.8 CMV-specific CD4+ T-cells/µL and ≥5.7 CD8+ T-cells/µL by ICS yielded excellent specificity (95.7% and 86.9%, respectively) and positive predictive values (PPVs) (>98.0%), but a sensitivity below 60%. A reactive QTF-CMV (IFN-γ ≥0.2 IU/mL) provided good sensitivity (81.6%) and PPV (92.5%), at the expense of a poor specificity (22.2%).

CONCLUSIONS

The discriminative capacity to predict immune protection against clinically relevant CMV infection among intermediate-risk KT recipients was comparable for ICS and QTF-CMV. A selected ICS threshold may provide better specificity than the interpretative cut-off values currently recommended for QTF-CMV.

Management of cytomegalovirus in adult solid organ transplant patients: GESITRA-IC-SEIMC, CIBERINFEC, and SET recommendations update

Cytomegalovirus (CMV) infection remains a significant challenge in solid organ transplantation (SOT). The last international consensus guidelines on the management of CMV in SOT were published in 2018, highlighting the need for revision to incorporate recent advances, notably in cell-mediated immunity monitoring, which could alter the current standard of care. A working group including members from the Group for the Study of Infection in Transplantation and the Immunocompromised Host (GESITRA-IC) of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) and the Spanish Society of Transplantation (SET), developed consensus-based recommendations for managing CMV infection in SOT recipients. Recommendations were classified based on evidence strength and quality using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. The final recommendations were endorsed through a consensus meeting and approved by the expert panel.

Slaying the "Troll of Transplantation"-new frontiers in cytomegalovirus management: A report from the CMV International Symposium 2023

The 2023 International CMV Symposium took place in Barcelona in May 2023. During the 2-day meeting, delegates and faculty discussed the ongoing challenge of managing the risk of cytomegalovirus infection (the Troll of Transplantation) after solid organ or hematopoietic cell transplantation. Opportunities to improve outcomes of transplant recipients by applying advances in antiviral prophylaxis or pre-emptive therapy, immunotherapy, and monitoring of cell-mediated immunity to routine clinical practice were debated and relevant educational clinical cases presented. This review summarizes the presentations, cases, and discussions from the meeting and describes how further advances are needed before the Troll of Transplantation is slain.

Advances in the regulatory mechanisms of mTOR in necroptosis

The mammalian target of rapamycin (mTOR), an evolutionarily highly conserved serine/threonine protein kinase, plays a prominent role in controlling gene expression, metabolism, and cell death. Programmed cell death (PCD) is indispensable for maintaining homeostasis by removing senescent, defective, or malignant cells. Necroptosis, a type of PCD, relies on the interplay between receptor-interacting serine-threonine kinases (RIPKs) and the membrane perforation by mixed lineage kinase domain-like protein (MLKL), which is distinguished from apoptosis. With the development of necroptosis-regulating mechanisms, the importance of mTOR in the complex network of intersecting signaling pathways that govern the process has become more evident. mTOR is directly responsible for the regulation of RIPKs. Autophagy is an indirect mechanism by which mTOR regulates the removal and interaction of RIPKs. Another necroptosis trigger is reactive oxygen species (ROS) produced by oxidative stress; mTOR regulates necroptosis by exploiting ROS. Considering the intricacy of the signal network, it is reasonable to assume that mTOR exerts a bifacial effect on necroptosis. However, additional research is necessary to elucidate the underlying mechanisms. In this review, we summarized the mechanisms underlying mTOR activation and necroptosis and highlighted the signaling pathway through which mTOR regulates necroptosis. The development of therapeutic targets for various diseases has been greatly advanced by the expanding knowledge of how mTOR regulates necroptosis.

Anti-CMV therapy, what next? A systematic review

Human cytomegalovirus (HCMV) is one of the main causes of serious complications in immunocompromised patients and after congenital infection. There are currently drugs available to treat HCMV infection, targeting viral polymerase, whose use is complicated by toxicity and the emergence of resistance. Maribavir and letermovir are the latest antivirals to have been developed with other targets. The approval of letermovir represents an important innovation for CMV prevention in hematopoietic stem cell transplant recipients, whereas maribavir allowed improving the management of refractory or resistant infections in transplant recipients. However, in case of multidrug resistance or for the prevention and treatment of congenital CMV infection, finding new antivirals or molecules able to inhibit CMV replication with the lowest toxicity remains a critical need. This review presents a range of molecules known to be effective against HCMV. Molecules with a direct action against HCMV include brincidofovir, cyclopropavir and anti-terminase benzimidazole analogs. Artemisinin derivatives, quercetin and baicalein, and anti-cyclooxygenase-2 are derived from natural molecules and are generally used for different indications. Although they have demonstrated indirect anti-CMV activity, few clinical studies were performed with these compounds. Immunomodulating molecules such as leflunomide and everolimus have also demonstrated indirect antiviral activity against HCMV and could be an interesting complement to antiviral therapy. The efficacy of anti-CMV immunoglobulins are discussed in CMV congenital infection and in association with direct antiviral therapy in heart transplanted patients. All molecules are described, with their mode of action against HCMV, preclinical tests, clinical studies and possible resistance. All these molecules have shown anti-HCMV potential as monotherapy or in combination with others. These new approaches could be interesting to validate in clinical trials.

Amplicon size and non-encapsidated DNA fragments define plasma cytomegalovirus DNA loads by automated nucleic acid testing platforms: A marker of viral cytopathology?

Management of cytomegalovirus (CMV) in transplant patients relies on measuring plasma CMV-loads using quantitative nucleic acid testing (QNAT). We prospectively compared the automated Roche-cobas®6800-CMV and Roche-CAP/CTM-CMV with laboratory-developed Basel-CMV-UL54-95bp, and Basel-CMV-UL111a-77bp. Roche-cobas®6800-CMV and Roche-CAP/CTM-CMV were qualitatively concordant in 142/150 cases (95%). In-depth comparison revealed higher CMV-loads of the laboratory-developed assay and correlated with smaller amplicon size. After calibration to the 1.WHO-approved CMV international standard, differences were reduced but remained significant. DNase-I pretreatment significantly reduced CMV-loads for both automated Roche-CAP/CTM-CMV and Roche-cobas®6800-CMV assays, whereby 90% and 95% of samples became undetectable. DNase-I pretreatment also reduced CMV-loads quantified by Basel-CMV-UL54-95bp and Basel-CMV-UL111a-77bp, but remaining detectable in 20% and 35%, respectively. Differences were largest for 110 samples with low-level CMV-DNAemia being detectable but not-quantifiable by Roche-cobas®6800-CMV, whereby the smaller amplicon sizes yielded higher viral loads for concordant positives. We conclude that non-encapsidated fragmented CMV-DNA is the major form of plasma CMV-loads also measured by fully-automated platforms. Amplicons of <150 bp and calibrators are needed for reliable and commutable QNAT-results. We hypothesize that non-encapsidated fragmented CMV-DNA results from lysis of CMV-replicating cells and represent a direct marker of viral cell damage, which contribute to delayed viral load responses despite effective antivirals.

The case for the therapeutic use of mechanistic/mammalian target of rapamycin (mTOR) inhibitors in xenotransplantation

The mechanistic/mammalian target of rapamycin (mTOR) is one of the systems that are necessary to maintain cell homeostasis, such as survival, proliferation, and differentiation. mTOR inhibitors (mTOR-Is) are utilized as immunosuppressants and anti-cancer drugs. In organ allotransplantation, current regimens infrequently include an mTOR-I, which are positioned more commonly as alternative immunosuppressants. In clinical allotransplantation, long-term efficacy has been established, but there is a significant incidence of adverse events, for example, inhibition of wound healing, buccal ulceration, anemia, hyperglycemia, dyslipidemia, and thrombocytopenia, some of which are dose-dependent. mTOR-Is have properties that may be especially beneficial in xenotransplantation. These include suppression of T cell proliferation, increases in the number of T regulatory cells, inhibition of pig graft growth, and anti-inflammatory, anti-viral, and anti-cancer effects. We here review the potential benefits and risks of mTOR-Is in xenotransplantation and suggest that the benefits exceed the adverse effects.