The impact of the prevention strategies on the indirect effects of CMV infection in solid organ transplant recipients

Letermovir safety and efficacy for cytomegalovirus prophylaxis in adult Japanese kidney transplant recipients: a multicenter, open-label, noncomparative Phase 3 study

BACKGROUND

Letermovir is approved for cytomegalovirus (CMV) prophylaxis in adult allogeneic hematopoietic cell transplantation recipients worldwide and is also approved in the United States for CMV prophylaxis in adult high-risk (D+/R-) kidney transplant recipients (KTRs). The safety and efficacy of letermovir for CMV prophylaxis in adult Japanese KTRs are reported here.

METHODS

In this Phase 3, single-arm, open-label study, adult Japanese KTRs with CMV serostatuses D+/R-, D+/R+, and D-/R+ received letermovir 480 mg daily orally within 7 days post-transplant through Week 28. Participants were followed through Week 52. The primary objective was to evaluate letermovir safety and tolerability. Efficacy was a secondary objective, measured by CMV disease, CMV disease or infection requiring intervention, and quantifiable CMV DNAemia. All CMV disease cases were confirmed by an independent adjudication committee.

RESULTS

Among 22 participants (12 were D+/R-) who received letermovir prophylaxis, 20 (90.9%) experienced ≥ 1 AE through Week 28. Most AEs were mild to moderate in severity; no deaths were reported. During the prophylaxis period through Week 28, one transient case of quantifiable CMV DNAemia was detected, but no CMV disease or infection requiring intervention was reported. Through Week 52, four D+/R- participants met the endpoint of CMV disease or infection requiring intervention, of whom two had committee-confirmed CMV syndrome; all recovered with CMV therapy. A total of 5 participants had quantifiable CMV DNAemia through Week 52.

CONCLUSION

Letermovir was generally well tolerated, and the data support its use for the prevention of CMV disease/infection in adult Japanese KTRs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04129398.

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.

Multicenter study of universal prophylaxis versus pre-emptive therapy for patients at intermediate risk (R+) for CMV following heart transplantation

INTRODUCTION

Heart transplant (HT) recipients with prior exposure to cytomegalovirus (CMV R+) are considered intermediate risk for CMV-related complications. Consensus guidelines allow for either universal prophylaxis (UP) or preemptive therapy (PET) (serial CMV testing) approaches to CMV prevention in such patients. Whether an optimal approach to mitigate CMV related risks exists in this setting remains uncertain. We therefore assessed the utility of PET as compared to UP in CMV R+ HT recipients.

METHODS

Retrospective analysis of all CMV R+ HT recipients from 6 U.S. centers between 2010 and 2018 was performed. The primary outcome was the development of CMV DNAemia or end-organ disease resulting in the initiation/escalation of anti-CMV therapy. The secondary outcome was CMV-related hospitalization. Additional outcomes included incidence of acute cellular rejection (ACR) ≥ grade 2R, death, cardiac allograft vasculopathy (CAV), and leukopenia.

RESULTS

Of 563 CMV R+ HT recipients, 344 (61.1%) received UP. PET was associated with increased risk for the primary (adjusted HR 3.95, 95% CI: 2.65-5.88, p < .001) and secondary (adjusted HR 3.19, 95% CI: 1.47-6.94, p = .004) outcomes, and with increased ACR ≥ grade 2R (PET 59.4% vs. UP 34.4%, p < .001). Incidence of detectable CAV was similar at 1 year (PET 8.2% vs. UP 9.5%, p = .698). UP was associated with increased incidence of leukopenia within 6 months post-HT (PET 34.7% vs. UP 43.6%, p = .036).

CONCLUSION

The use of a PET CMV prophylaxis strategy in intermediate risk HT recipients associated with increased risk of CMV infection and CMV-related hospitalization, and may associate with worse post-HT graft outcomes.

Prediction of herpes virus infections after solid organ transplantation: a prospective study of immune function

Introduction

Herpes virus infections are a major concern after solid organ transplantation and linked to the immune function of the recipient. We aimed to determine the incidence of positive herpes virus (cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus type 1/2 (HSV-1/2), and varicella zoster virus (VZV)) PCR tests during the first year post-transplantation and assess whether a model including immune function pre-transplantation and three months post-transplantation could predict a subsequent positive herpes virus PCR.

Methods

All participants were preemptively screened for CMV, and EBV IgG-negative participants were screened for EBV during the first year post-transplantation. Herpes virus PCR tests for all included herpes viruses (CMV, EBV, HSV-1/2, and VZV) were retrieved from the Danish Microbiology database containing nationwide PCR results from both hospitals and outpatient clinics. Immune function was assessed by whole blood stimulation with A) LPS, B) R848, C) Poly I:C, and D) a blank control. Cytokine concentrations (TNF-α, IL-1β, IL-6, IL-8, IL-10, IL-12p40, IL-17A, IFN-α, and IFN-γ) were measured using Luminex.

Results

We included 123 liver (54%), kidney (26%), and lung (20%) transplant recipients. The cumulative incidence of positive herpes virus PCR tests was 36.6% (95% CI: 28.1-45.1) during the first year post-transplantation. The final prediction model included recipient age, type of transplantation, CMV serostatus, and change in Poly I:C-induced IL-12p40 from pre-transplantation to three months post-transplantation. The prediction model had an AUC of 77% (95% CI: 61-92). Risk scores were extracted from the prediction model, and the participants were divided into three risk groups. Participants with a risk score <5 (28% of the cohort), 5-10 (45% of the cohort), and >10 (27% of the cohort) had a cumulative incidence of having a positive herpes virus PCR test at 5.8%, 25%, and 73%, respectively (p < 0.001).

Conclusion

In conclusion, the incidence of positive herpes virus PCR tests was high, and a risk model including immune function allowed the prediction of positive herpes virus PCR and may be used to identify recipients at higher risk.

Relationship between Cytomegalovirus Viremia and Long-Term Outcomes in Kidney Transplant Recipients with Different Donor Ages

OBJECTIVES

To explore the Cytomegalovirus (CMV) burden on the long-term post-transplant course in different donor ages, we evaluated the incidence and risk factors for CMV in our kidney-transplanted patients (KTs) with extensive adoption of expanded-criteria donors (ECDs).

METHODS

Retrospective evaluation of 929 consecutive first KTs (49.5% receiving an organ from a donor ≥ 60 years) performed between 01-2003 and 12-2013. Overall survival was estimated using Kaplan-Meier curves; cumulative incidence function was additionally analyzed to consider the potential role of death with a functioning graft as a competitive event with graft dysfunction and to avoid overestimation. Apart from regular DNAemia monitoring in all patients, prophylaxis was adopted in high-risk groups (D+/R- or recipients of anti-thymocyte globulin induction), with pre-emptive therapy in the remaining groups.

RESULTS

CMV incidence was 19.5% (4-34.9% according to serostatus combination: D-/R-, D-/R+, D+/R+, D+/R-). Donor and recipient age, recipient pre-transplant hypertension, DR antigen compatibility, cold ischemia time, and post-transplant early complications, including rejection, urologic and renal artery stenosis, and lower renal function and proteinuria ≥ 0.5 g/day at one year after KT were associated with CMV. CMV determined lower death-censored graft survival (DCGS) (p < 0.01), with a prominent effect in R+ (p < 0.01) and without impact in R- (p = 0.32 in D-/R- and p = 0.006 in D+/R-). Interestingly, CMV occurrence influenced DCGS only in KTs who received grafts from donors < 50 or 50-69 years old (p < 0.01), while it was not significant with older donors (p = 0.07). The analysis of the cumulative incidence of graft loss accounting for death as a competing risk confirmed all these findings. In multivariate analysis, CMV replication/disease in the first year was an independent predictor for DCGS (HR 1.73 [1.3-2.3]).

CONCLUSIONS

In a large population with extensive ECD adoption, CMV viremia in the first year demonstrates its harmful effect with an independent role for graft loss and significant impact among R+ recipients and KTs with donors < 70 years.

Cytomegalovirus Therapy: Role of Letermovir in Prophylaxis and Treatment in Transplant Recipients

Cytomegalovirus (CMV) is a common viral pathogen in the transplant population and is associated with significant morbidity and mortality. CMV prevention is paramount; however, selecting the best preventive strategy depends on many factors including donor-recipient CMV serostatus, transplant-specific risks, antiviral toxicities and cost. Novel CMV therapeutics such as letermovir (LTV) are desperately needed to optimize CMV management. Uniquely among CMV antiviral therapies, LTV inhibits the viral terminase complex in the CMV DNA synthesis pathway and disrupts viral genome packaging. Further, it lacks side effects frequently associated with other CMV antiviral therapies and evades common mechanisms of resistance. LTV is approved by the US Food and Drug Administration for CMV prevention in adult CMV-seropositive hematopoietic cell transplant recipients but is increasingly applied off-label for prophylaxis and treatment. This review summarizes important concepts of CMV management in transplantation, with a specific focus on LTV pharmacology and clinical experience to date alongside future prospects for its application.

Antiviral prophylaxis or preemptive therapy for cytomegalovirus after liver transplantation?: A systematic review and meta-analysis

BACKGROUND

To conduct a meta-analysis with the aim of comparing the outcomes of antiviral prophylaxis and preemptive therapy for the prevention of cytomegalovirus (CMV) infection in liver transplant (LT) recipients.

METHODS

We searched databases for qualified studies up until March 2022. Finally, a meta-analysis was carried out using a fixed-effect or random-effect model based on the heterogeneity.

RESULTS

With a total of 1834 LT patients, the pooled incidence of CMV infection and CMV disease in the overall LT recipients using antiviral prophylaxis and preemptive therapy were 24.7% vs. 40.4% and 6.4% vs. 9.4%, respectively. Our meta-analysis exhibited a significant reduction in the incidence of CMV infection due to antiviral prophylaxis when compared to preemptive therapy in the high-risk group (OR: 6.67, 95% CI: 1.73, 25.66; p = 0.006). In contrast, there was a significant reduction in the incidence of late-onset of CMV disease in preemptive therapy compared to antiviral prophylaxis in the high-risk group (OR: 0.29, 95% CI: 0.12, 0.74; p = 0.009). However, the incidence of CMV disease, allograft rejection, graft loss, drug related adverse effects, opportunistic infections and mortality did not differ significantly between both the interventions (all p> 0.05).

CONCLUSIONS

We found the use of antiviral prophylaxis, compared with preemptive therapy, is superior in controlling CMV infection and prolonging the time to CMV disease in LT recipients without an increased risk of opportunistic infections, allograft rejection, graft loss, drug related adverse effects, development of drug resistance, and mortality.

Cytomegalovirus Exposure and the Risk of Overall Infection After Kidney Transplantation: A Cohort Study on the Indirect Effects Attributable to Viral Replication

Previous reports hypothesized that cytomegalovirus (CMV) may predispose to non-CMV infection after kidney transplantation (KT). We analysed the incidence of non-CMV infection (overall, bacterial and opportunistic) in 291 KT recipients according to the previous development of any level or high-level (≥1,000 IU/ml) CMV viremia. Exposure to CMV replication was assessed throughout fixed intervals covering first the 30, 90, 180 and 360 post-transplant days (cumulative exposure) and non-overlapping preceding periods (recent exposure). Adjusted Cox models were constructed for each landmark analysis. Overall, 67.7 and 50.5% patients experienced non-CMV and CMV infection, respectively. Patients with cumulative CMV exposure had higher incidence of non-CMV infection beyond days 30 (p-value = 0.002) and 90 (p-value = 0.068), although these associations did not remain after multivariable adjustment. No significant associations were observed for the remaining landmark models (including those based on high-level viremia or recent CMV exposure), or when bacterial and opportunistic infection were separately analysed. There were no differences in viral kinetics (peak CMV viremia and area under curve of CMV viral load) either. Our findings do not support the existence of an independent association between previous CMV exposure and the overall risk of post-transplant infection, although results might be affected by power limitations.

Acute and Chronic Changes in Gene Expression After CMV DNAemia in Kidney Transplant Recipients

Cytomegalovirus (CMV) viremia continues to cause significant morbidity and mortality in kidney transplant patients with clinical complications including organ rejection and death. Whole blood gene expression dynamics in CMV viremic patients from onset of DNAemia through convalescence has not been well studied to date in humans. To evaluate how CMV infection impacts whole blood leukocyte gene expression over time, we evaluated a matched cohort of 62 kidney transplant recipients with and without CMV DNAemia using blood samples collected at multiple time points during the 12-month period after transplant. While transcriptomic differences were minimal at baseline between DNAemic and non-DNAemic patients, hundreds of genes were differentially expressed at the long-term timepoint, including genes enriching for pathways important for macrophages, interferon, and IL-8 signaling. Amongst patients with CMV DNAemia, the greatest amount of transcriptomic change occurred between baseline and 1-week post-DNAemia, with increase in pathways for interferon signaling and cytotoxic T cell function. Time-course gene set analysis of these differentially expressed genes revealed that most of the enriched pathways had a significant time-trend. While many pathways that were significantly down- or upregulated at 1 week returned to baseline-like levels, we noted that several pathways important in adaptive and innate cell function remained upregulated at the long-term timepoint after resolution of CMV DNAemia. Differential expression analysis and time-course gene set analysis revealed the dynamics of genes and pathways involved in the immune response to CMV DNAemia in kidney transplant patients. Understanding transcriptional changes caused by CMV DNAemia may identify the mechanism behind patient vulnerability to CMV reactivation and increased risk of rejection in transplant recipients and suggest protective strategies to counter the negative immunologic impact of CMV. These findings provide a framework to identify immune correlates for risk assessment and guiding need for extending antiviral prophylaxis.

Cytomegalovirus mismatch after heart transplantation: Impact of antiviral prophylaxis and intravenous hyperimmune globulin

Objective

Cytomegalovirus (CMV) infections are correlated with complications following heart transplantation (HTx) and impaired outcome. The impact of a serologic mismatch between donor and recipient and the necessity of prophylactic virostatic medication is still a matter of concern.

Methods

We retrospectively reviewed all patients that underwent HTx between 2010 and 2020 in our department. The recipients (n = 176) could be categorized into four risk groups depending on their serologic CMV matching (D⁺/R⁻ = donor CMV‐IgG positive and recipient CMV‐IgG negative, n = 32; D⁻/R⁺, n = 51; D⁻/R⁻, n = 35; D⁺/R⁺, n = 58). All patients followed the same protocol of CMV prophylaxis with application of ganciclovir/valganciclovir and intravenous CMV hyperimmune globulin.

RESULTS

Incidence of postoperative morbidity such as primary graft dysfunction, neurological events, infections, and graft rejection were comparable between all groups (p > .05). However, the incidence of postoperative acute kidney injury with hemodialysis was by trend increased in the D⁻/R⁺ group (72.0%) compared to the other groups. In‐hospital CMV‐DNAemia was observed in serologic positive recipients only (D⁺/R⁻: 0.0%, D⁻/R⁺: 25.0%, D⁻/R⁻: 0.0%, D⁺/R⁺: 13.3%, p < .01). During the first year, a total of 18 patients developed CMV‐DNAemia (D⁺/R⁻: 31.6%, D⁻/R⁺: 31.9%, D⁻/R⁻: 3.4%, D⁺/R⁺: 11.1%, p = .03).

Conclusions

Seropositive recipients carry an important risk for CMV‐DNAemia. However, we did not observe differences in perioperative morbidity and mortality regarding CMV matching, which might be related to regularly administer prophylactic virostatics and additional CMV‐IVIG for risk constellations. For high‐risk constellation, long‐term application of CMV‐IVIG during the first year after transplant may be beneficial.

Care for the organ transplant recipient on the intensive care unit

All transplant recipients receive tacrolimus, mycophenolate and glucocorticoids and these drugs have many side-effects and drug-drug interactions. Common complications include surgical complications, infections, rejection and acute kidney injury. Infections as CMV and PJP can be prevented with prophylactic treatment. Given the complexity of organ transplant recipients a multi-disciplinary team of intensivists, surgeons, pharmacists and transplant specialists is essential. After heart transplantation a temporary pacemaker is required until the conduction system recovers. Stiffening of the heart and increased cardiac markers indicate rejection. An endomyocardial biopsy is performed via the right jugular vein, necessitating its preservation. For lung transplant patients, early intervention for aspiration is warranted to prevent chronic rejection. Risk of any infection is high, requiring active surveillance and intensive treatment, mainly of fungal infections. The liver is immunotolerant requiring lower immunosuppression. Transplantation surgery is often accompanied by massive blood loss and coagulopathy. Other complications include portal vein or hepatic artery thrombosis and biliary leakage or stenosis. Kidney transplant recipients have a high risk of cardiovascular disease and posttransplant anemia should be treated liberally. After postmortal transplantation, delayed graft function is common and dialysis is continued. Ureteral anastomosis complications can be diagnosed with ultrasound.

CMV infection, valganciclovir exposure, and the risk of BK viremia and associated nephropathy after kidney transplantation: Is there a link?

BACKGROUND

Immunomodulatory effects attributable to cytomegalovirus (CMV) would predispose to BK polyomavirus (BKPyV) infection after kidney transplantation (KT), although available evidence is conflicting. It has been suggested that (val)ganciclovir therapy may increase the risk of BKPyV viremia and BKPyV-associated nephropathy (BKPyVAN) as a result of drug-induced T-cell impairment.

METHODS

We investigated whether CMV replication and/or (val)ganciclovir exposure (either as prophylaxis or treatment) were associated with the development of BKPyV viremia or BKPyVAN in a prospective cohort of 399 KT recipients. CMV infection (any level or high-level viremia and area under the curve of DNAemia) and (val)ganciclovir exposure (any duration of therapy and cumulative days of treatment) during the first post-transplant year were explored through separate landmark survival analyses.

RESULTS

Cumulative incidence of BKPyV viremia and BKPyVAN after a median follow-up of 551 days was 23.1% and 2.5%, respectively. One-year rates of CMV infection and (val)ganciclovir therapy were 47.4% and 54.1%, respectively. No differences were observed in BKPyV viremia- or BKPyVAN-free survival according to previous CMV infection or (val)ganciclovir exposure in any of the landmark analyses. Adjusted Cox models confirmed this lack of association.

CONCLUSION

Our findings do not confirm the existence of a relevant impact of CMV infection or (val)ganciclovir therapy on the risk of post-transplant BKPyV events.

Early cytomegalovirus DNAemia and antiviral dose adjustment in high vs intermediate risk kidney transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection continues to negatively affect outcomes for solid organ transplant recipients, despite the advent of strategies for preemptive surveillance and prophylaxis. The impact is especially great for CMV seronegative recipients of donor seropositive organs, who typically lack the ability to control CMV infection at the time of transplantation.

METHODS

We reviewed episodes of CMV DNAemia in a modern cohort of kidney transplant recipients over a 3-year period at a high-volume transplant center to investigate the frequency of DNAemia during antiviral prophylaxis.

RESULTS

Despite receipt of antiviral prophylaxis per current guidelines, 75 cases of CMV DNAemia were observed in the first 100 days after transplantation. For high risk patients, median time to DNAemia was 75 days after transplantation, and the majority of patients had experienced dose-reduction of valganciclovir due to renal insufficiency. Review of CMV seropositive intermediate risk patients demonstrated DNAemia occurring earlier after transplantation compared with high risk patients with a median time of 64 days (P = .029). The impact of valganciclovir dose adjustment was less notable in the intermediate risk group.

CONCLUSIONS

Guidelines recommend beginning routine surveillance for CMV after the completion of antiviral prophylaxis. Our findings suggest that closer monitoring may be beneficial, especially for high risk patients at risk for DNAemia. Patients requiring dose adjustment of valganciclovir due to renal insufficiency may be at increased risk for CMV DNAemia. Improved methods for CMV prophylaxis and evaluation of immunologic risk for CMV DNAemia and disease are needed to improve patient outcomes after kidney transplantation.

Clinical features of BK-polyomavirus and cytomegalovirus co-infection after kidney transplantation

BK polyomavirus (BKPyV) and cytomegalovirus (CMV) are the main viral pathogens affecting the graft and recipient outcome after allogenic kidney transplantation. It has recently been found that infection with both viruses has a greater impact on kidney graft function than a single infection. We retrospectively analyzed a cohort of 723 recipients who received kidney transplantation between 2007 and 2015 after living and postmortal donation for differences in risk and outcome parameters regarding BKPyV (DNAemia) and CMV (CMV DNAemia) co-infection compared to sole viremias and to patients without viremia. Of all kidney allograft recipients in our cohort, 8.2% developed co-infection with BKPyV DNAemia and CMV DNAemia, 15.1% showed BKPyV viremia alone and 25.2% sole CMV DNAemia. Acute rejection was closely linked with co-infection (multivariable analysis, p = 0.001). Despite the fact that the estimated glomerular filtration rate of patients with co-infection was noticeably reduced compared to patients with BKV or CMV infection alone, transplant survival and patient survival were not significantly reduced. Co-infection with BKPyV and CMV in kidney transplanted patients is significantly associated with inferior allograft function. Since co-infection is strongly associated with acute rejection, co-infected individuals should be considered a risk collective.

Cytomegalovirus after kidney transplantation in 2020: moving towards personalized prevention

Cytomegalovirus (CMV)-related complications after kidney transplantation remain a substantial challenge. Rather than applying one preventive strategy to all at-risk patients, we can now adapt our strategy at the individual patient level. Antiviral prophylaxis or a strict pre-emptive strategy may be optimal for patients at the highest risk for CMV, while patients at lower risk may benefit particularly from pre-emptive monitoring and the administration of therapy only if needed. CMV-specific T-cell assays may be useful for further refining the pre-transplant determination of CMV risk, and for guiding decisions about antiviral therapy need or duration. An immunosuppressive regimen including a mammalian target of rapamycin inhibitor reduces CMV risk and may thus be an attractive option in some patients. New antiviral agents may further expand our therapeutic arsenal in the near future, and the prospects of CMV vaccination and adoptive T-cell therapy appear to be on the horizon.

Immunosuppressive Agents and Infectious Risk in Transplantation: Managing the "Net State of Immunosuppression"

Successful solid organ transplantation reflects meticulous attention to the details of immunosuppression, balancing risks for graft rejection against risks for infection. The 'net state of immune suppression' is a conceptual framework of all factors contributing to infectious risk. Assays which measure immune function in the immunosuppressed transplant recipient relative to infectious risk and allograft function are lacking. The best measures of integrated immune function may be quantitative viral loads to assess the individual's ability to control latent viral infections. Few studies address adjustment of immunosuppression during active infections. Thus, confronted with infection in solid organ recipients, the management of immunosuppression is based largely on clinical experience. This review examines known measures of immune function and the immunologic effects of common immunosuppressive drugs and available studies reporting modification of drug regimens for specific infections. These data provide a conceptual framework for the management of immunosuppression during infection in organ recipients.

Immunosuppressive Drug-Associated Adverse Event Profiles in De Novo Kidney Transplant Recipients Receiving Everolimus and Reduced Tacrolimus Doses

BACKGROUND

The safety of immunosuppressive regimens is influenced by the induction agent, maintenance drug combination, and prophylactic strategy for cytomegalovirus (CMV) infection. Herein, this safety analysis compares rabbit antithymocyte globulin (r-ATG) or basiliximab (BAS) combined with everolimus (EVR) versus BAS combined with mycophenolate sodium (MPS) in kidney transplant recipients receiving tacrolimus, prednisone, and preemptive CMV therapy.

METHODS

In this single-center, prospective, randomized study, adverse events (AEs), serious AEs (SAEs), viral infections, laboratory abnormalities, dose reductions, and temporary or permanent discontinuation of the immunosuppressant were compared among patients receiving r-ATG/EVR (n = 85), BAS/EVR (n = 102), and BAS/MPS (n = 101).

RESULTS

A total of 2741 AEs and 344 SAEs were observed. There were no differences in the proportion of patients with at least one AE (96% versus 98% versus 96%, respectively; P > 0.05). The proportion of patients with at least one SAE was highest in the BAS/MPS group (33% versus 48% versus 69%, respectively; P < 0.05). This difference was due primarily to a high incidence of CMV infection in the BAS/MPS group (4.7% versus 10.8% versus 37.6%, respectively). The incidence of mild/moderate abnormalities in creatinine, cholesterol, and triglyceride levels was higher in both EVR groups. The cumulative freedom from dose reduction or treatment discontinuation due to an AE was higher in both EVR groups than in the BAS/MPS group (89.2% versus 92.8% versus 76.3%, respectively, P = 0.003). There was no difference in the incidence of biopsy-confirmed acute rejection (9.4% versus 18.6 versus 15.8%, respectively; P = 0.403).

CONCLUSIONS

This analysis suggests that r-ATG induction combined with EVR is associated with a comparable incidence of acute rejection, lower incidence of CMV infection, and fewer changes in initial immunosuppressive regimen due to AEs in kidney transplant recipients receiving tacrolimus, prednisone, and preemptive CMV therapy.

Prevention and therapy of viral infections in patients with solid organ transplantation

Solid organ transplantation (SOT) is the best treatment option for end-stage organ disease. The number of SOT procedures has been steadily increasing worldwide during the past decades. This trend has been accompanied by the continuous incorporation of new antimicrobial drugs and by the refinement of strategies aimed at minimizing the risk of opportunistic infection. Nonetheless, viral infections, which can occur at any stage of the post-transplant period, remain a clinical challenge that negatively impacts both patient and graft outcomes. This review offers an overview of the most relevant viral infections in the SOT population, with a focus on herpesviruses (cytomegalovirus, Epstein-Barr virus, varicella-zoster virus, and herpes simplex virus 1 and 2) and polyomaviruses (human BK polyomavirus). In addition, the currently recommended prophylactic and treatment approaches are summarized, as well as the new antiviral agents in different phases of clinical development.

Cytomegalovirus Viremia after Living and Deceased Donation in Kidney Transplantation

Despite screening, effective anti-viral drugs and risk-balanced prophylaxis, cytomegalovirus (CMV) remains a major cause of morbidity in transplant patients. The objective of this study was to retrospectively analyze the risk factors associated with CMV viremia after kidney transplantation in a large European cohort with standardized valganciclovir prophylaxis in the present era. A special focus was placed on the comparison of living and postmortal donation. We conducted a longitudinal observational study involving 723 adult patients with a total of 3292 patient-years who were transplanted at our center between 2007 and 2015. Valganciclovir prophylaxis was administered over 100 days for CMV+ donors (D) or recipients (R), over 200 days for D+/R−, and none in D−/R−. A CMV+ donor, rejection episodes, and deceased donor transplantation were identified to be associated with increased incidences of CMV viremia. Although we did not find a reduced overall survival rate for patients with CMV viremia, it was associated with worse graft function. Since we observed a relevant number of CMV infections despite prescribing valganciclovir prophylaxis, a pre-emptive strategy in patients with (suspected) adherence restrictions could be favored. Our data can help transplant physicians educate their patients about their individual CMV risk and choose the most appropriate CMV treatment approach.

The impact of recurrent cytomegalovirus infection on long-term survival in solid organ transplant recipients

BACKGROUND

Cytomegalovirus (CMV) remains a significant contributor to morbidity and mortality following solid organ transplantation (SOT). While recurrent infection occurs in up to 30% of patients, its impact on mortality is unclear. The aim of this study was to explore the relationship between recurrent CMV infection and long-term survival in SOT recipients.

METHODS

We performed a retrospective cohort study of SOT recipients who completed treatment for an episode of CMV infection. Patients were followed until death, loss to follow-up or 10 years following CMV treatment completion. Univariable and multivariable hazard ratios (HR) were calculated, treating relapse and rejection following CMV as time-varying.

RESULTS

About 79 kidney, 52 heart, 34 liver, and 5 liver-kidney transplant recipients were included. About 62/170 died, at a median of 3.8 years (IQR 0.8-6.6 years). Median follow-up among the 108 survivors was 7.4 years (IQR 3.7-10 years). Recurrent CMV infection occurred in 49/170 (29%), 67% within 6 months of treatment completion. Mortality among those who relapsed was 39% (19/49) vs 36% (43/121) in those who remained relapse-free (unadjusted HR 1.59, 95% CI 0.92-2.75, P = .10). After adjusting for age and transplanted organ, findings were similar (HR 1.68, 95% CI 0.93-3.04, P = .09).

CONCLUSIONS

Mortality following CMV remains high even in the valganciclovir era. Although our findings suggest a possible increased risk of death among patients with recurrent CMV, these did not reach statistical significance. The complex nature of these patients, multiple potential confounders, and limited statistical power made detection of small effects difficult. Larger prospective studies evaluating the clinical impact of strategies to reduce recurrence are needed.

Clinical Correlation of Cytomegalovirus Infection With CMV-specific CD8+ T-cell Immune Competence Score and Lymphocyte Subsets in Solid Organ Transplant Recipients. Transplantation. 2019;103:832-838. [PMID: 30086091 DOI: 10.1097/tp.0000000000002396]

BACKGROUND

Control of cytomegalovirus (CMV) infection after solid organ transplantation (SOT) requires a functional immune system. We assessed the association between quantitation and function of CMV-specific CD8+ T cells and CMV infection in SOT recipients.

METHODS

During a 10-year period, selected kidney, heart, lung, pancreas, liver, and composite tissue recipients were tested for CMV-specific CD8+ T cells immune competence (CMV-CD8+), as measured by enumeration, interferon-gamma production, and CD107a/b degranulation. Quantitative and functional data were used to assemble T-cell immune competence (TIC) score. CMV infection was diagnosed by polymerase chain reaction in blood and other samples or histopathology.

RESULTS

Of 130 patients tested, 59 had CMV infection or disease. The median onset to CMV infection was 10.5 months (interquartile range [IQR], 5.5-18.7). Gastrointestinal disease (28.8%), pneumonia (20.3%), and CMV syndrome (17%) were most common presentation. An impaired nonspecific or CMV-CD8+ TIC score was associated with tissue-invasive disease (hazard risk, 2.84, 95% confidence interval, 1.03-11.81; P = 0.04). Patients with impaired CMV-CD8+ TIC score had longer viremia duration (42.4 days vs 18.8 d; P < 0.001). Patients with impaired nonspecific or CMV-CD8+ TIC score had higher risk of relapse (68.8% vs 27.9%; hazard risk, 2.56; 95% confidence interval, 1.09-5.89; P = 0.03). Patients with CMV infection or disease had lower median absolute lymphocyte count (380 [IQR, 240-540] vs 940 [IQR, 551-1210] cells/mm; P < 0.0001) and CD4+ T cell count (29 cells/mm [IQR, 1.3-116.0] vs 325.5 cells/mm [IQR, 151.5-589.8]; P < 0.0001).

CONCLUSIONS

Nonspecific and CMV-specific CD8+ T-cell function correlated with the course of CMV after SOT, and measuring these has the potential to assist in its clinical management.

NKG2C Natural Killer Cells in Bronchoalveolar Lavage Are Associated With Cytomegalovirus Viremia and Poor Outcomes in Lung Allograft Recipients

BACKGROUND

Cytomegalovirus (CMV) infection is a risk factor for chronic lung allograft dysfunction (CLAD), which limits survival in lung allograft recipients. Natural killer (NK) cells that express the NKG2C receptor mediate CMV-specific immune responses. We hypothesized that NKG2C NK cells responding to CMV in the lung allograft would reduce CMV-related inflammation and would improve CLAD-free survival.

METHODS

We prospectively followed 130 subjects who underwent lung transplantation from 2012 to 2016. Bronchoalveolar lavage (BAL) NK cells were immunophenotyped for NKG2C, maturation, and proliferation markers. CMV viral load, serologies, serial spirometry, and mortality were recorded from medical records. Natural killer cell subset association with CMV endpoints were made using generalized estimating equation-adjusted linear models. BAL NKG2C NK cell association with CLAD-free survival was assessed by Cox proportional hazards modeling.

RESULTS

NKG2C NK cells were more mature and proliferative than NKG2C NK cells and represented a median of 7.8% of BAL NK cells. The NKG2C NK cell proportion increased prior to the first detection of viremia and was nearly tripled in subjects with high level viremia (>1000 copies/mL) compared with no detected viremia. Subjects with increased BAL NKG2C NK cells, relative to the median, had a significantly increased risk for CLAD or death (hazard ratio, 4.2; 95% confidence interval, 1.2-13.3).

CONCLUSIONS

The BAL NKG2C NK cell proportion may be a relevant biomarker for assessing risk of CMV viremia and quantifying potential CMV-related graft injury that can lead to CLAD or death.

Clinical significance of human cytomegalovirus viruria and the effect of antiviral therapy in hematopoietic stem cell transplant recipients

BACKGROUND

Cytomegalovirus (CMV) causes life-threatening infections in immunocompromised host. The clinical significance of asymptomatic CMV viruria in patients receiving hematopoietic stem cell transplantation (HSCT) remains unclear. This study aims to clarify whether antiviral therapy is associated with a favorable clinical outcome.

METHODS

HSCT recipients whose urine was culture-positive for CMV were retrospectively reviewed and followed. Viruria episodes were divided according to whether or not antiviral therapy was used. Mortality and the estimated glomerular filtration rate (eGFR) in 2 years following CMV viruria were compared between patients with and without antiviral therapy.

RESULTS

Sixty-two episodes of culture-proven asymptomatic CMV viruria were identified in 28 HSCT recipients. Antiviral therapy was used in 35 (56.5%) and spared in 27 (43.5%) viruric episodes. Compared with the baselines, there were no significant difference in the decrements of eGFR between the two groups at the end the 1st year (4.78 vs 5.02 mL/min/1.73 m², p = 0.968) and the 2nd year (1.13 vs 7.66 mL/min/1.73 m², p = 0.276). Antiviral therapy for asymptomatic CMV viruria was also not associated with a favorable survival (p = 0.288). On the other hand, presence of CMV viremia correlated with a poorer survival (2-year mortality rate 60% vs 13.33%, p < 0.001).

CONCLUSION

Antiviral therapy for asymptomatic CMV viruria is not associated with a clear clinical benefit in HSCT recipients. Further studies may be needed to identify if specific patient populations may benefit from antiviral therapy in CMV viruria.

Cytomegalovirus and Epstein-Barr virus infections among pediatric kidney transplant recipients at a center using universal Valganciclovir Prophylaxis

BACKGROUND

CMV is associated with adverse effects in renal transplant recipients. The objective of this study was to characterize the incidence and timing of CMV and EBV infections in relation to valGCV prophylaxis in a pediatric renal transplant cohort.

METHODS

Retrospective cohort of pediatric renal transplant patients given universal valGCV prophylaxis and universal viral surveillance was evaluated. Demographics, prophylaxis, acute rejection, and CMV and EBV infections were abstracted.

RESULTS

A total of 92 pediatric renal allograft recipients, 2008-2013, were included. One or more viral infections developed in 77/92 (83.7%) of the patients. EBV was the most common in 62/92 (67%) patients, irrespective of valGCV (82% of episodes occurring on valGCV). CMV DNAemia occurred in 30/92 (33%) patients, 14 episodes (47%) occurring on valGCV. Incidence of breakthrough CMV on prophylaxis was 15% and was associated with persistent DNAemia (OR 7.8, CI:1.6-32.9, P < 0.02). CMV tissue-invasive disease was not seen. CMV syndrome occurred in 10% of the cohort, only in CMV D+ patients, and only one symptomatic breakthrough infection required treatment. Out of 92, 21 (23%) had simultaneous co-infections with 2-3 viruses.

CONCLUSIONS

Viral infections in pediatric renal transplant recipients receiving universal valGCV prophylaxis were common. EBV infections were not reduced by valGCV prophylaxis, and nearly half of CMV infections occurred on valGCV. Symptomatic CMV infection while on prophylaxis was rare. valGCV prophylaxis may prevent symptomatic CMV infection but not EBV infection, and frequent CMV surveillance in pediatric renal transplant recipients on prophylaxis may not be necessary.

Cytomegalovirus mismatch still negatively affects patient and graft survival in the era of routine prophylactic and preemptive therapy: A paired kidney analysis

The impact of cytomegalovirus (CMV) serostatus on kidney transplant outcomes in an era when CMV prophylactic and preemptive strategies are used routinely is not clearly established. Using United Network for Organ Sharing/Organ Procurement and Transplantation Network data, recipients with first deceased donor kidney transplant (≥18 years, 2010-2015) were stratified into 4 groups in the main cohort: CMV-seronegative donor (D-)/CMV-seronegative recipient (R-), CMV-seropositive donor (D+)/R-, D+/CMV-seropositive recipient (R+), and D-/R+. In a paired kidney cohort, we identified 2899 pairs of D- kidney transplant with discordance of recipient serostatus (D-/R- vs D-/R+) and 4567 pairs of D+ kidney transplant with discordance of recipient serostatus (D+/R- vs D+/R+). In the main cohort, D+/R- was associated with a higher risk of graft failure (hazard ratio [HR] = 1.17, P = .01), all-cause mortality (HR = 1.18, P < .001), and infection-related mortality (HR = 1.38, P = .03) compared with D-/R-. In the paired kidney analysis, D+/R- was an independent risk factor for all-cause mortality (HR = 1.21, P = .003) and infection-related mortality (HR = 1.47, P = .04) compared with D+/R+. No difference in graft loss between D+/R- and D+/R+. CMV mismatch is still an independent risk factor for graft loss and patient mortality. The negative impact of D+/R- serostatus on mortality persists after fully matching for donor factors.

Common viral infections in kidney transplant recipients

Infectious complications have been considered as a major cause of morbidity and mortality after kidney transplantation, especially in the Asian population. Therefore, prevention, early detection, and prompt treatment of such infections are crucial in kidney transplant recipients. Among all infectious complications, viruses are considered to be the most common agents because of their abundance, infectivity, and latency ability. Herpes simplex virus, varicella zoster virus, Epstein-Barr virus, cytomegalovirus, hepatitis B virus, BK polyomavirus, and adenovirus are well-known etiologic agents of viral infections in kidney transplant patients worldwide because of their wide range of distribution. As DNA viruses, they are able to reactivate after affected patients receive immunosuppressive agents. These DNA viruses can cause systemic diseases or allograft dysfunction, especially in the first six months after transplantation. Pretransplant evaluation and immunization as well as appropriate prophylaxis and preemptive approaches after transplant have been established in the guidelines and are used effectively to reduce the incidence of these viral infections. This review will describe the etiology, diagnosis, prevention, and treatment of viral infections that commonly affect kidney transplant recipients.

Late cytomegalovirus (CMV) infections after kidney transplantation under the preemptive strategy: Risk factors and clinical aspects

BACKGROUND

Late cytomegalovirus infections (LCMV) after the cessation of prophylaxis are well described. We aimed to assess clinical and epidemiological data on late-occurring cytomegalovirus (CMV) infections in the absence of CMV prophylaxis in a cohort of kidney transplant patients.

METHODS

In a cohort of kidney transplant recipients not employing CMV-specific prophylaxis, patients with CMV infections occurring after 6 months of transplantation were compared to patients with CMV infections diagnosed within the first 6 months (early infections). The main objectives were to compare clinical outcomes and evaluate risk factors for late CMV infection.

RESULTS

A total of 556 patients were evaluated. Forty-three patients with LCMV infections were compared to 513 patients with early CMV infections. LCMV infections occurred after a median of 473 days of transplantation and had a more severe course, with a statistically significant higher rate of invasive disease and graft loss (60.5% vs 21.6% and 11.6% vs 3.1% respectively). Thirty-day mortality was twice as high for patients with LCMV, but did not reach statistical significance (9.3% vs 4.3%). By multivariate analysis, employment of antilymphocyte therapy early after transplantation and tacrolimus as initial immunosuppressive therapy were significantly protective for the occurrence of LCMV infections.

CONCLUSION

Late CMV infections in the absence of specific prophylaxis after kidney transplantation have a more severe outcome when compared to early infections and occur in patients less immunosuppressed early after transplantation.

Treatment and Prevention of CMV Disease in Transplant Recipients: Current Knowledge and Future Perspectives

This review summarizes the significant impact of cytomegalovirus (CMV) infection on solid organ and hematopoietic stem cell transplant recipients. A discussion of the various CMV prevention and treatment strategies is provided, including a detailed description of each of the available CMV antiviral drugs.

Impact of donor and recipient cytomegalovirus serology on long-term survival of heart transplant recipients

BACKGROUND

Some studies have shown that pre-transplant cytomegalovirus (CMV) serostatus is associated with heart transplant patient survival while others have not. We analyzed the relationship between pre-transplant donor/recipient CMV serostatus and long-term mortality in a retrospective cohort of heart transplant recipients at our center.

METHODS

Adult (Age >17 years) heart recipients transplanted between July 1985-December 2015 were analyzed. Variables included age, sex, pre-transplant donor (D)/recipient (R) serostatus [D-/R-, D-/R+, D+/R+, D+/R-], CMV infection within 2 years of transplant and transplant eras divided by changes in CMV prevention strategies: Era 1 (Pre-ganciclovir, July 1985-April 1998), Era 2 (Oral ganciclovir, May 1998-December 2004), Era 3 (Valganciclovir, January 2005-December 2015). Survival analysis and Cox regression were performed at 10 years.

RESULTS

A total of 620 heart transplants were included in our analysis; 20% were CMV mismatched pre-transplant. Thirty-eight percent of patients were infected with CMV within the first two post-transplant years. Survival analysis showed D/R CMV serostatus did not significantly impact survival of heart recipients at 10 years (P = 0.11). Survival was significantly different across eras for D-/R+, D+/R+, and D+/R+ (P = 0.043) but not D-/R- patients (P = 0.8). Cox regression revealed that patients transplanted in the valganciclovir era have an estimated 29% reduced risk of death (P = 0.047) compared to patients transplanted in the pre-ganciclovir era after controlling for age at transplantation, D/R CMV serostatus and CMV infection.

CONCLUSION

Our review of the impact of CMV managed differently across eras suggests in heart transplantation there is no influence of D/R CMV serostatus on 10 year survival.

Natural killer cells in lung transplantation

Natural killer (NK) cells are innate lymphoid cells that have been increasingly recognised as important in lung allograft tolerance and immune defence. These cells evolved to recognise alterations in self through a diverse set of germline-encoded activating and inhibitory receptors and display a broad range of effector functions that play important roles in responding to infections, malignancies and allogeneic tissue. Here, we review NK cells, their diverse receptors and the mechanisms through which NK cells are postulated to mediate important lung transplant clinical outcomes. NK cells can promote tolerance, such as through the depletion of donor antigen-presenting cells. Alternatively, these cells can drive rejection through cytotoxic effects on allograft tissue recognised as 'non-self' or 'stressed', via killer cell immunoglobulin-like receptor (KIR) or NKG2D receptor ligation, respectively. NK cells likely mediate complement-independent antibody-mediated rejection of allografts though CD16A Fc receptor-dependent activation induced by graft-specific antibodies. Finally, NK cells play an important role in response to infections, particularly by mediating cytomegalovirus infection through the CD94/NKG2C receptor. Despite these sometimes-conflicting effects on allograft function, enumeration of NK cells may have an important role in diagnosing allograft dysfunction. While the effects of immunosuppression agents on NK cells may currently be largely unintentional, further understanding of NK cell biology in lung allograft recipients may allow these cells to serve as biomarkers of graft injury and as therapeutic targets.

New therapies for human cytomegalovirus infections

The recent approval of letermovir marks a new era of therapy for human cytomegalovirus (HCMV) infections, particularly for the prevention of HCMV disease in hematopoietic stem cell transplant recipients. For almost 30 years ganciclovir has been the therapy of choice for these infections and by today's standards this drug exhibits only modest antiviral activity that is often insufficient to completely suppress viral replication, and drives the selection of drug-resistant variants that continue to replicate and contribute to disease. While ganciclovir remains the therapy of choice, additional drugs that inhibit novel molecular targets, such as letermovir, will be required as highly effective combination therapies are developed not only for the treatment of immunocompromised hosts, but also for congenitally infected infants. Sustained efforts, largely in the biotech industry and academia, have identified additional highly active lead compounds that have progressed into clinical studies with varying levels of success and at least two have the potential to be approved in the near future. Some of the new drugs in the pipeline inhibit new molecular targets, remain effective against isolates that have developed resistance to existing therapies, and promise to augment existing therapeutic regimens. Here, we will describe some of the unique features of HCMV biology and discuss their effect on therapeutic needs. Existing drugs will also be discussed and some of the more promising candidates will be reviewed with an emphasis on those progressing through clinical studies. The in vitro and in vivo antiviral activity, spectrum of antiviral activity, and mechanism of action of new compounds will be reviewed to provide an update on potential new therapies for HCMV infections that have progressed significantly in recent years.

Impact of donor and recipient cytomegalovirus serology on long-term survival of lung transplant recipients

BACKGROUND

Pre-transplant cytomegalovirus (CMV) serostatus has been associated with lung transplant patient survival. We retrospectively analyzed the relationship between pre-transplant donor/recipient CMV serostatus and long-term mortality in a cohort of lung transplant recipients at our center.

METHOD

Adult (Age >17 years) lung recipients transplanted between July 1985-December 2015 were analyzed. Variables included age, sex, pre-transplant donor (D)/recipient (R) serostatus [D-/R-, D-/R+, D+/R+, D+/R-], CMV infection within 2 years of transplant and transplant eras divided by changes in CMV prevention strategies: Era 1 (pre-ganciclovir, July 1985-April 1998), Era 2 (oral ganciclovir, May 1998-December 2004), Era 3 (valganciclovir, January 2005-December 2015). Survival analysis and Cox regression were performed at 10 years.

RESULTS

A total of 652 lung recipients were analyzed. Twenty percent were CMV mismatched pre-transplant and 45% had CMV infection within 2 years post-transplant. Survival at 10 years appeared worse in D+ transplants (P = 0.027). D-/R- lungs did not have significantly different survival across eras (P = 0.76), but survival of D-/R+, D+/R+, D+/R- lungs improved (P < 0.001). Cox regression revealed that transplantation in the valganciclovir era reduced risk of death in lung transplants by an estimated 52% (P < 0.001) compared to transplantation in the pre-ganciclovir era after controlling for age at transplant, D/R CMV serostatus and CMV infection. Age at transplant and CMV infection were also significant predictors of mortality in lung transplants (P < 0.001 and 0.033 respectively).

CONCLUSION

Our review of the impact of CMV managed differently across eras suggests in lung transplantation there is no independent influence of D/R CMV serostatus on 10-year survival.

Cardiovascular disease after transplantation: an emerging role of the immune system

Cardiovascular disease (CVD) after transplantation remains a major concern. Little is known about what drives the increased cardiovascular risk in transplant recipients apart from traditional risk factors. The immune system is involved in the pathogenesis of hypertension, atherosclerosis, and coronary artery disease in the general population. Recently, inhibition of interleukin 1 - β by canakinumab versus placebo decreased the incidence of cardiovascular events. Emerging evidence points to a role of adaptive cellular immunity in the development of CVD. Especially, expansion of pro-inflammatory and antiapoptotic cytotoxic CD4⁺ CD28^null T cells is closely associated with incident CVD in various study populations including transplant recipients. The association of cytomegalovirus exposure with increased cardiovascular mortality might be explained by its capacity to upregulate these cytotoxic cells. Also, humoral immunity seems to be relevant for cardiovascular outcome in transplant recipients. Panel-reactive antibodies at baseline and donor-specific antibodies are independently associated with poor cardiovascular outcome after kidney transplantation. Cardiovascular effects of immunosuppressive drugs and statins do not only imply indirect positive or negative effects on traditional cardiovascular risk factors but also intrinsic immunological effects. How immunosuppressive drugs modify atherosclerosis largely remains elusive.

Monitoring of Cytomegalovirus (CMV)-Specific Cell-Mediated Immunity in Heart Transplant Recipients: Clinical Utility of the QuantiFERON-CMV Assay for Management of Posttransplant CMV Infection

The clinical utility of the QuantiFERON-CMV (QFN-CMV) assay in heart transplant recipients was assessed. Forty-four cytomegalovirus (CMV)-seropositive patients were enrolled: 17 received antiviral prophylaxis, and 27 were managed preemptively. CMV-DNAemia monitoring was performed by the use of a quantitative real-time PCR assay. The QFN-CMV assay was retrospectively performed on blood samples collected at five posttransplant time points. A higher proportion of patients with an indeterminate QFN-CMV result after the suspension of prophylaxis than of patients who showed a global T-cell responsiveness developed CMV infection (P = 0.036). Patients who reconstituted a CMV-specific response following the first CMV-DNAemia-positive result (42.9%) showed a median CMV-DNAemia peak 1 log of magnitude lower than that seen with patients with indeterminate results, and all controlled viral replication spontaneously. The 25% of patients with an indeterminate result developed CMV disease. In the preemptive strategy group, no differences in the development of subsequent infection, magnitude of viral load, and viral control were observed on the basis of QFN-CMV measurements performed before and after the first CMV-DNAemia-positive result. Considering both CMV prevention strategies, viral relapse was associated with the failure to reconstitute CMV-specific cell-mediated immunity (CMI) after the resolution of the first episode of CMV infection (P = 0.032). QFN-CMV measurements can be a useful tool for identifying patients (i) at higher risk of developing infection after discontinuing antiviral prophylaxis, (ii) with late CMV infection who would benefit from appropriate antiviral interventions, and (iii) at higher risk of viral relapses. QFN-CMV measurements taken within 1 month posttransplantation (early period) are not revealing.

The Potential Harm of Cytomegalovirus Infection in Immunocompetent Critically Ill Children

Cytomegalovirus (CMV) is a ubiquitous infection that causes disease in congenitally infected children and immunocompromised patients. Although nearly all CMV infections remain latent and asymptomatic in immunologically normal individuals, numerous studies have found that systemic viral reactivation is common in immunocompetent critically ill adults, as measured by detection of CMV in the blood (viremia). Furthermore, CMV viremia is strongly correlated with adverse outcomes in the adult intensive care unit (ICU), including prolonged stay, duration of mechanical ventilation, and death. Increasing evidence, including from a randomized clinical trial of antiviral treatment, suggests that these effects of CMV may be causal. Therefore, interventions targeting CMV might improve outcomes in adult ICU patients. CMV may have an even greater impact on critically ill children, particularly in low and middle income countries (LMIC), where CMV is regularly acquired in early childhood, and where inpatient morbidity and mortality are inordinately high. However, to date, there are few data regarding the clinical relevance of CMV infection or viremia in immunocompetent critically ill children. We propose that CMV infection should be studied as a potential modifiable cause of disease in critically ill children, and that these studies be conducted in LMIC. Below, we briefly review the role of CMV in immunologically normal critically ill adults and children, outline age-dependent differences in CMV infection that may influence ICU outcomes, and describe an agenda for future research.

The Human Virome: Implications for Clinical Practice in Transplantation Medicine

Advances in DNA sequencing technology have provided an unprecedented opportunity to study the human virome. Transplant recipients and other immunocompromised hosts are at particular risk for developing virus-related pathology; thus, the impact of the virome on health and disease may be even more relevant in this population. Here, we discuss technical considerations in studying the human virome, the current literature on the virome in transplant recipients, and near-future applications of sequence-based findings that can further our understanding of viruses in transplantation medicine.

Transfusion-transmitted CMV infection - current knowledge and future perspectives

Transmission of human cytomegalovirus (CMV) via transfusion (TT-CMV) may still occur and remains a challenge in the treatment of immunocompromised CMV-seronegative patients, e.g. after stem cell transplantation, and for low birthweight infants. Measures to reduce the risk of TT-CMV have been evaluated in clinical studies, including leucocyte depletion of cellular blood products and/or the selection of CMV-IgG-negative donations. Studies in large blood donor cohorts indicate that donations from newly CMV-IgG-positive donors should bear the highest risk for transmitting CMV infections because they contain the highest levels of CMV-DNA, and early CMV antibodies cannot neutralise CMV. Based on this knowledge, rational strategies to reduce the residual risk of TT-CMV using leucoreduced blood products could be designed. However, there is a lack of evidence that CMV is still transmitted by transfusion of leucoreduced units. In low birthweight infants, most (if not all) CMV infections are caused by breast milk feeding or congenital transmission rather than by transfusion of leucoreduced blood products. For other patients at risk, no definitive data exist about the relative importance of alternative transmission routes of CMV compared to blood transfusion. As a result, only the conduction of well-designed studies addressing strategies to prevent TT-CMV and the thorough examination of presumed cases of TT-CMV will achieve guidance for the best transfusion regimen in patients at risk.

Cytomegalovirus Vaccines: Current Status and Future Prospects

Congenital human cytomegalovirus (HCMV) infection can result in severe and permanent neurological injury in newborns, and vaccine development is accordingly a major public health priority. HCMV can also cause disease in solid organ transplant (SOT) and hematopoietic stem-cell transplant (HSCT) recipients, and a vaccine would be valuable in prevention of viremia and end-organ disease in these populations. Currently there is no licensed HCMV vaccine, but progress toward this goal has been made in recent clinical trials. A recombinant HCMV glycoprotein B (gB) vaccine has been shown to have some efficacy in prevention of infection in young women and adolescents, and has provided benefit to HCMV-seronegative SOT recipients. Similarly, DNA vaccines based on gB and the immunodominant T-cell target, pp65 (ppUL83), have been shown to reduce viremia in HSCT patients. This review provides an overview of HCMV vaccine candidates in various stages of development, as well as an update on the current status of ongoing clinical trials. Protective correlates of vaccine-induced immunity may be different for pregnant woman and transplant patients. As more knowledge emerges about correlates of protection, the ultimate licensure of HCMV vaccines may reflect the uniqueness of the target populations being immunized.

Primary Cytomegalovirus Infection in Seronegative Kidney Transplant Patients Is Associated with Protracted Cold Ischemic Time of Seropositive Donor Organs

Human Cytomegalovirus (CMV) can lead to primary infection or reactivation in CMV-seronegative or -seropositive kidney transplant recipients, respectively. Complications comprise severe end-organ diseases and acute or chronic transplant rejection. Risk for CMV manifestation is stratified according to the CMV-IgG-serostatus, with donor+/recipient- (D+/R-) patients carrying the highest risk for CMV-replication. However, risk factors predisposing for primary infection in CMV-seronegative recipients are still not fully elucidated. Therefore, we monitored D+/R- high-risk patients undergoing kidney transplantation in combination with antiviral prophylaxis for the incidence of CMV-viremia for a median follow-up time of 784 days (156–1155 days). In this period, we analyzed the functional CMV-specific T cell response by intracellular cytokine staining and CMV-serology by ELISA. Only four of eight D+/R- patients developed clinically relevant CMV-viremia followed by seroconversion. Viremia triggered expansion of functional CMV-specific T cells correlating with protection against secondary CMV-reactivations. In contrast, all other patients remained permanently aviremic and showed no immunological correlate of infection after discontinuation of antiviral prophylaxis for up to three years. Comparing cold ischemic times (CIT) of viremic (median = 1020 min; 720–1080 min) and aviremic patients (median = 335 min; 120–660 min) revealed significantly (p = 0.0286) protracted CIT in patients with primary CMV-infection. Taken together, primary CMV-infection affects only a subgroup of D+/R- patients correlating with length of CIT. Therefore, patients with extended CIT should be thoroughly monitored for CMV-replication well beyond discontinuation of antiviral prophylaxis. In contrast, patients with short CIT remained permanently uninfected and might benefit from shorter prophylactic treatment.

Immunological Prediction of Cytomegalovirus (CMV) Replication Risk in Solid Organ Transplantation Recipients: Approaches for Regulating the Targeted Anti-CMV Prevention Strategies

The current cytomegalovirus (CMV) prevention strategies in solid organ transplantation (SOT) recipients have contributed towards overcoming the detrimental effects caused by CMV lytic infection, and improving the long-term success rate of graft survival. Although the quantification of CMV in peripheral blood is the standard method, and an excellent end-point for diagnosing CMV replication and modulating the anti-CMV prevention strategies in SOT recipients, a novel biomarker mimicking the CMV control mechanism is required. CMV-specific immune monitoring can be employed as a basic tool predicting CMV infection or disease after SOT, since uncontrolled CMV replication mostly originates from the impairment of immune responses against CMV under immunosuppressive conditions in SOT recipients. Several studies conducted during the past few decades have indicated the possibility of measuring the CMV-specific cell-mediated immune response in clinical situations. Among several analytical assays, the most advancing standardized tool is the QuantiFERON®-CMV assay. The T-Track® CMV kit that uses the standardized enzyme-linked immunospot assay is also widely employed. In addition to these assays, immunophenotyping and intracellular cytokine analysis using flow cytometry (with fluorescence-labeled monoclonal antibodies or peptide-major histocompatibility complex multimers) needs to be adequately standardized and validated for potential clinical applications.

Evaluation of T Cell Immunity against Human Cytomegalovirus: Impact on Patient Management and Risk Assessment of Vertical Transmission

Cytomegalovirus (CMV) is one of the most common infectious agents, infecting the general population at an early age without causing morbidity most of the time. However, on particular occasions, it may represent a serious risk, as active infection is associated with rejection and disease after solid organ transplantation or fetal transmission during pregnancy. Several methods for CMV diagnosis are available on the market, but because infection is so common, careful selection is needed to discriminate primary infection from reactivation. This review focuses on methods based on CMV-specific T cell reactivity to help monitor the consequences of CMV infection/reactivation in specific categories of patients. This review makes an attempt at discussing the pros and cons of the methods available.

CMV Immunoglobulins for the Treatment of CMV Infections in Thoracic Transplant Recipients

Intravenous ganciclovir and, increasingly, oral valganciclovir are now considered the mainstay of treatment for cytomegalovirus (CMV) infection or CMV disease. Under certain circumstances, CMV immunoglobulin (CMVIG) may be an appropriate addition or, indeed, alternative. Data on monotherapy with CMVIG are limited, but encouraging, for example in cases of ganciclovir intolerance. In cases of recurrent CMV in thoracic transplant patients after a disease- and drug-free period, adjunctive CMVIG can be considered in patients with hypogammaglobulinemia. Antiviral-resistant CMV, which is more common among thoracic organ recipients than in other types of transplant, can be an indication for introduction of CMVIG, particularly in view of the toxicity associated with other options, such as foscarnet. Due to a lack of controlled trials, decision-making is based on clinical experience. In the absence of a robust evidence base, it seems reasonable to consider the use of CMVIG to treat CMV in adult or pediatric thoracic transplant patients with ganciclovir-resistant infection, or in serious or complicated cases. The latter can potentially include (i) treatment of severe clinical manifestations, such as pneumonitis or eye complications; (ii) patients with a positive biopsy in end organs, such as the lung or stomach; (iii) symptomatic cases with rising polymerase chain reaction values (for example, higher than 5.0 log₁₀) despite antiviral treatment; (iv) CMV disease or CMV infection or risk factors, such as CMV-IgG–negative serostatus; (vi) ganciclovir intolerance; (vii) patients with hypogammaglobulinemia.

Analysis of pulmonary non-tuberculous mycobacterial infections after lung transplantation

PURPOSE

Non-tuberculous mycobacteria (NTM) are important pathogens in lung transplant recipients. This study describes the spectrum of NTM respiratory tract infections and examines the association of NTM infections with lung transplant complications.

METHODS

Data from 208 recipients transplanted from November 1990 to November 2005 were analyzed. Follow-up data were available to November 2010. Lung infection was defined by bronchoalveolar lavage, sputum, or blood cultures in the appropriate clinical setting. All identified NTM respiratory tract infections were tabulated. The cohort of patients with NTM lung infections (NTM+) were compared to the cohort without infection (NTM-). Univariate and multivariate analysis was performed to determine characteristics associated with NTM infection. Survival analyses for overall survival and development of bronchiolitis obliterans syndrome (BOS) were also performed.

RESULTS

In total, 52 isolates of NTM lung infection were identified in 30 patients. The isolates included Mycobacterium abscessus (46%), Mycobacterium avium complex (MAC) (36%), Mycobacterium gordonae (9%), Mycobacterium chelonae (7%), and Mycobacterium fortuitum (2%), with multiple NTM isolates seen on 3 different occasions. The overall incidence was 14%, whereas cumulative incidences at 1, 3, and 5 years after lung transplantation were 11%, 15%, and 20%, respectively. Comparisons between the NTM+ and NTM- cohorts revealed that NTM+ patients were more likely to be African-American and have cytomegalovirus mismatch. Although no difference was seen in survival, the NTM+ cohort was more likely to develop BOS (80% vs. 58%, P = 0.02). NTM+ infection, however, was not independently associated with development of BOS by multivariate analysis.

CONCLUSION

With nearly 20 years of follow-up, 14% of lung recipients develop NTM respiratory tract infections, with M. abscessus and MAC more commonly identified. M. gordonae was considered responsible for nearly 10% of NTM infections. Although survival of patients with NTM infections is similar, a striking difference in BOS rates is present in the NTM+ and NTM- groups.

Polyfunctional T-Cell Signatures to Predict Protection from Cytomegalovirus after Lung Transplantation

RATIONALE

Cytomegalovirus (CMV), which is one of the most common infections after lung transplantation, is associated with chronic lung allograft dysfunction and worse post-transplantation survival. Current approaches for at-risk patients include a fixed duration of antiviral prophylaxis despite the associated cost and side effects.

OBJECTIVES

We sought to identify a specific immunologic signature that predicted protection from subsequent CMV.

METHODS

CMV-seropositive lung transplantation recipients were included in the discovery (n = 43) and validation (n = 28) cohorts. Polyfunctional CMV-specific immunity was assessed by stimulating peripheral blood mononuclear cells with CMV pp65 or IE-1 peptide pools and then by measuring T-cell expression of CD107a, IFN-γ, tumor necrosis factor-α (TNF-α), and IL-2. Recipients were prospectively monitored for subsequent viremia. A Cox proportional hazards regression model that considered cytokine responses individually and in combination was used to create a predictive model for protection from CMV reactivation. This model was then applied to the validation cohort.

MEASUREMENTS AND MAIN RESULTS

Using the discovery cohort, we identified a specific combination of polyfunctional T-cell subsets to pp65 that predicted protection from subsequent CMV viremia (concordance index 0.88 [SE, 0.087]). The model included both protective (CD107a(-)/IFN-γ(+)/IL-2(+)/TNF-α(+) CD4(+) T cells, CD107a(-)/IFN-γ(+)/IL-2(+)/TNF-α(+) CD8(+) T cells) and detrimental (CD107a(+)/IFN-γ(+)/IL-2(-)/TNF-α(-) CD8(+) T cells) subsets. The model was robust in the validation cohort (concordance index 0.81 [SE, 0.103]).

CONCLUSIONS

We identified and validated a specific T-cell polyfunctional response to CMV antigen stimulation that provides a clinically useful prediction of subsequent cytomegalovirus risk. This novel diagnostic approach could inform the optimal duration of individual prophylaxis.

Use of Everolimus-based Immunosuppression to Decrease Cytomegalovirus Infection After Kidney Transplant

OBJECTIVES

Cytomegalovirus infection and disease remain an issue in solid-organ transplant. Universal prophylaxis is more cost-effective than a preemptive strategy and is associated with significantly less Cytomegalovirus resistance after kidney transplant, especially in Cytomegalovirus-seropositive donors and Cytomegalovirus-seronegative recipients.

MATERIALS AND METHODS

Registry data and meta-analyses have shown that mammalian target of rapamycin inhibitors (sirolimus- and everolimus-based immunosuppression) are associated with significantly less Cytomegalovirus events in de novo kidney transplant patients than in patients who are treated with calcineurin inhibitors plus mycophenolate-based immunosuppression.

RESULTS

Recent pooled analyses of 3 randomized controlled trials in de novo kidney transplant patients, where immunosuppression was based on cyclosporine with either mycophenolate or everolimus, showed that patients who received everolimus had significantly less Cytomegalovirus events (Cytomegalovirus viremia, Cytomegalovirus infection/disease) than those who received mycophenolate, with or without cytomegalovirus as prophylaxis. An even more recent prospective randomized controlled study on de novo kidney transplant patients with no anticytomegalovirus prophylaxis demonstrated that everolimus-based immunosuppression plus low-dose tacrolimus was associated with significantly less Cytomegalovirus infection than standard-dose tacrolimus plus mycophenolate.

CONCLUSIONS

The potential benefits are not fully known of such a therapeutic strategy to limit the long-term indirect effects mediated by Cytomegalovirus infections.