Prevention of CMV disease in pediatric kidney transplant recipients: evaluation of pp67 NASBA-based pre-emptive ganciclovir therapy combined with CMV hyperimmune globulin prophylaxis in high-risk patients

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.

Infections in pediatric solid-organ transplant recipients

Solid-organ transplantation in pediatrics can be a life-saving procedure, but it cannot be accomplished without risk of infection-related morbidity and mortality. Evaluation of the recipient during candidacy and donor during evaluation can assist with identification of risk. Further, risk of infection from the surgical procedure can be mitigated through careful planning and attention to infection prevention processes. Finally, early recognition of infection posttransplant can limit the impact of these events.

Efficacy of Extended Valganciclovir Prophylaxis in Preventing Cytomegalovirus Infection in Pediatric Kidney Transplantation

Cytomegalovirus (CMV) is one of the most frequent opportunistic infection in renal transplant (RTx) recipients. Valganciclovir (VGC) has been showed to be safe and highly effective in prophylaxis of CMV infection in RTx recipients. Recently, an increase in delayed onset CMV disease has been noted with some arguing that longer prophylaxis may decrease the late-onset disease.

We retrospectively tested the hypothesis that extended term prophylaxis (ETP) of VGC for 12 months is more effective than short term prophylaxis (STP) of 6 months in preventing CMV infection and disease in pediatric RTx performed at the University of Florida from July 2003 to December 2010. In this period, all recipients underwent prospective CMV PCR (Polymerase Chain Reaction) monitoring and were maintained on similar immunosuppression.

Eighty six patients received RTx during that period. All eligible subjects had to have at least 12 months of graft survival and 18 months of follow up, leaving 73 eligible subjects in final study group. CMV infection or disease occurred in 6/29 (20%) in the STP group vs 6/44 (14%) in the ETP group with no statistical significant difference (P= 0.42). Donor positive/recipients negative CMV serology status (D+/R-) were associated with a higher risk of CMV infection in both univariate and multivariate analysis (P=0.01). Anemia and Leucopenia directly associated with VGC were similar in both groups (P=0.58 and P=0.2 respectively). Biopsy-proven acute rejection was also non-significant in both groups (P=0.39).

Although ETP for CMV from 6 months to 12 months is safe and has minimal adverse effect, it did not reduce CMV infection or disease. Further controlled studies in pediatrics age group are considered to compare longer versus shorter periods of prophylaxis and their impact on prevention of CMV infection, resistance, cost, and toxicity.

Reconstitution of protective immune responses against cytomegalovirus and varicella zoster virus does not require disease development in pediatric recipients of umbilical cord blood transplantation

CMV and varicella zoster virus (VZV) are significant causes of morbidity and mortality following umbilical cord blood transplantation (UCBT). However, the kinetics of reconstitution and protective potential of antiviral cell-mediated immune responses following UCBT remain poorly characterized. In this study, the reconstitution of CMV- and VZV-specific T cell responses was assessed using IFN-γ ELISPOT in 28 children who underwent UCBT to treat hematological or inherited disorders. Barely detectable in the first 3 mo posttransplantation, CMV- and VZV-specific T cell responses were observed in 30.4% and 40.3% of study subjects after 36 mo of follow-up. Four of five CMV-seropositive subjects developed detectable levels of circulating CMV DNA (DNAemia), and 5 of 17 VZV-seropositive patients experienced herpes zoster during the posttransplant period. Four CMV-seronegative subjects developed IFN-γ responses against CMV, and four subjects developed a VZV-specific IFN-γ response without clinical signs of infection. No CMV- or VZV-related events were observed in study subjects following the development of CMV- or VZV-specific responses > 150 spot-forming units/10(6) PBMCs, consistent with T cell-mediated protection. Finally, famciclovir prophylaxis did not strictly prevent the reconstitution of the VZV-specific T cell repertoire, because the frequency of T cells producing IFN-γ in response to VZV Ags reached levels consistent with protection in two nonzoster subjects. Monitoring of CMV- and VZV-specific cell-mediated immunity could inform immunocompetence and guide the initiation and cessation of antiherpetic prophylaxis in UCBT recipients.

Correlation and clinical utility of pp65 antigenemia and quantitative polymerase chain reaction assays for detection of cytomegalovirus in pediatric renal transplant patients

qPCR and pp65 antigenemia assays are used to monitor CMV infection in renal transplant recipients, but correlation of assays in a pediatric population has not been evaluated. Paired CMV real-time qPCR and pp65 antigenemia tests from 882 blood samples collected from 115 pediatric renal transplant recipients were analyzed in this retrospective cohort study for the strength of association and clinical correlates. The assays correlated well in detecting infection (κ = 0.61). Higher qPCR values were demonstrated with increasing levels of antigenemia (p < 0.01). Discordant test results were associated with antiviral treatment (OR 4.33, p < 0.01) and low-level viremia, with odds of concordance increasing at higher qPCR values (OR 3.67, p < 0.01), and no discordance occurring above 8500 genomic equivalents/mL. Among discordant samples, neither test preceded the other in detecting initial infection or in returning to negative while on treatment. Only two cases of disease occurred during the two-yr study period. With strong agreement in the detection of CMV infection, either qPCR or pp65 antigenemia assays can be used effectively for monitoring pediatric renal transplant patients for both detection and resolution of infection.

Cytomegalovirus risk, prevention, and management in pediatric solid organ transplantation

Cytomegalovirus (CMV) is an important cause of morbidity and mortality in children who have received organ transplants. Patients have been reported to be at differential risk for CMV disease based on the serostatus of the donor and recipient with highest risk reported for CMV seronegative recipients who receive an organ from a CMV seropositive donor. Prophylaxis with ganciclovir and/or oral valganciclovir is reasonable to attempt to prevent CMV infections. A hybrid strategy bridging prophylaxis and pre-emptive therapy appears to be emerging as an additional method to prevent CMV disease. However, there is no agreement on the optimal schedule of testing, duration and dosing of antiviral medications or the role of immunoglobulin therapy. This manuscript will review the most recent literature and recommendations for the prophylaxis and treatment of CMV infections and disease in pediatric transplant recipients. Multicenter, randomized, clinical studies involving several pediatric transplant centers are needed to determine the best strategies to prevent and treat CMV infections in these patients.

24 weeks of valganciclovir prophylaxis in children after renal transplantation: a 4-year experience

BACKGROUND

Cytomegalovirus (CMV) is the most common opportunistic infection after solid-organ transplant. Valganciclovir prophylaxis significantly reduces disease, but limited data are available on its use in children. Recently, an increase in delayed-onset CMV disease has been noted with some arguing that longer prophylaxis may decrease late-onset disease.

METHODS

Single-center, retrospective analysis of pediatric renal transplant patients receiving 24 weeks valganciclovir prophylaxis (15 mg/kg/day, maximum 900 mg/day) from January 2004 to December 2008, aiming to measure the incidence of CMV disease and toxicity of valganciclovir.

RESULTS

We enrolled 111 patients, 60% males, 46% African Americans, and median age at transplant 14.5 years (range 1.4-20.4 years). Sixty-nine percent of donors and 44% of recipients were seropositive pretransplant. Median duration of valganciclovir use was 5.9 months (range 0.5-24 months). CMV viremia and disease occurred in 27% and 4.5%, respectively. All patients with disease presented after prophylaxis ended and all were D+/R-. Thymoglobulin use (P = 0.04) and positive donor CMV status (P = 0.02) were associated with a higher risk of CMV viremia. Twenty-four percent had hematologic toxicity directly associated with valganciclovir.

CONCLUSIONS

Valganciclovir use in children was effective as prophylaxis against CMV disease; no children at our institution developed disease while on therapy. Our regimen of 24 weeks of prophylaxis was associated with a lower rate of late-onset disease than previous reports with 12-week regimens. Further controlled studies should be considered to compare longer versus shorter periods of prophylaxis and dose reductions and their impact on prevention of late-onset disease, resistance, cost, and toxicity.

The value of immunoprophylaxis for cytomegalovirus infection with intravenous immunoglobulin in pediatric liver transplant recipients receiving a low-dose immunosupressive regimen

The incidence of CMV infection following pediatric Ltx is particularly high, which can be attributed to the increased number of patients at high risk for primary infection (donor CMV+, recipient CMV-). Current approaches to cope with this complication producing post-operative morbidity include prophylactic or preemptive ganciclovir therapy. As the risk for symptomatic CMV infection is directly correlated with the intensity of immunosuppression, the aim of our study was to assess the value of IVIG in order to protect children receiving low-dose immunosuppression from CMV disease. Twenty-eight consecutive children (median age 62.2 months) at high risk prospectively received three infusions of IVIG on days four, 14, and 28 post-transplant and were monitored for six months post-Ltx. Immunosuppression consisted of cyclosporine (initial trough levels 170-200 microg/L) and prednisolone (starting dose 15 mg/m(2)) as well as basiliximab induction therapy. Patient survival was 100% and graft survival was 92.9%. Two subjects developed laboratory findings of CMV infection (8%) and one child suffered from tissue invasive CMV disease (4%). Three patients were excluded from the study because of protocol violations. We conclude that there was a low incidence of CMV disease among a prospective cohort receiving low-dose immunosuppression and a standard IVIG product.