Cytomegalovirus disease in high-risk transplant recipients despite ganciclovir or valganciclovir prophylaxis

Cytomegalovirus-Associated Colitis as a Cause of Lower Gastrointestinal Bleeding in Kidney Transplant Recipients: A Single-Centered Study

Introduction Cytomegalovirus (CMV) is the most common viral pathogen affecting patients undergoing solid organ transplantation. It is often the most important infection for patients who have undergone kidney transplantation. Clinical presentations of cytomegalovirus infection range from asymptomatic infection to organ-specific involvement. This study aimed to determine the frequency of cytomegalovirus-associated colitis in kidney transplant recipients (KTRs) presenting with lower gastrointestinal bleeding. Methods After the approval of the ethical review committee of the Sindh Institute of Urology and Transplantation (ERC-SIUT), this cross-sectional study was conducted at the Department of Hepatogastroenterology at the Sindh Institute of Urology and Transplantation from January 2021 to December 2021. All the KTRs (six months after the transplantation) of either gender and aged between 18 and 65 years, presenting with lower gastrointestinal (GI) bleeding as per the operational definition, were enrolled in the study. Those patients who were either unfit for the endoscopy or refused to give consent were excluded from the study. Colonic biopsies were reviewed by a consultant histopathologist for the features of CMV infection. Results A total of 95 renal transplant recipients of either gender or age above 18 to 65 years with lower GI bleeding were included in the study. Among them, 84 (88.4%) were males, while 11 (11.6%) were females. The mean age of the patients included in the study was 37±11 years. The most common presenting complaint was fresh bleeding per rectum, which was observed in 73 (76.8%). The most common findings observed on colonoscopy in KTRs with bleeding per rectum were colonic ulcers and erosions noted in 41 (43.1%) and 36 (37.3%) patients, respectively. On histopathology, CMV colitis was noted in 21 (22.1%) patients. On comparison of different baseline variables, the presence of fresh bleeding per rectum and the presence of both ulcers and erosions on colonoscopy were the factors significantly associated with CMV colitis in KTRs. Conclusion CMV colitis is a prevalent condition in KTRs, presenting with lower GI bleeding. Despite the significant occurrence, the levels of CMV viremia were not associated with CMV colitis, suggesting that diagnosis should rely on histopathological confirmation. Prophylaxis during periods of high immunosuppression is crucial to reducing the incidence of CMV infections and improving both graft function and patient survival.

Low-Dose Valganciclovir Prophylaxis Against Cytomegalovirus in Intermediate-Risk Liver and Dual-Abdominal Transplant Recipients

BACKGROUND

Low-dose valganciclovir (VGC) for cytomegalovirus (CMV) prophylaxis post-transplant has been employed due to cost and safety. The incidence of CMV disease in CMV intermediate-risk liver recipients at 1-year after standard-dose prophylaxis is approximately 5%. However, there are limited data on outcomes after using a "true" low-dose VGC prophylaxis regimen in liver and dual-abdominal transplant recipients as VGC was not dose-adjusted in all patients with impaired renal function in prior studies.

OBJECTIVE

The objective was to assess the incidence of CMV associated with low-dose VGC prophylaxis in CMV intermediate-risk liver, simultaneous pancreas-kidney (SPK), and simultaneous liver-kidney (SLK) recipients with creatinine clearance (CrCl) >60 mL/min.

METHODS

This was a retrospective review of CMV intermediate-risk liver, SPK, and SLK recipients with CrCl >60 mL/min transplanted January 2018 to June 2022 who received VGC 450 mg daily for prophylaxis. The primary outcome was incidence of CMV infection 6-months post-transplant.

RESULTS

Ninety-nine transplant recipients were included (79 liver, 11 SPK, 9 SLK). The primary outcome occurred in 13% of patients (liver 10%, SPK 36%, SLK 10%), including 1 case of CMV disease and 3 breakthrough infections. In addition, 6 patients experienced CMV infection between 6-months and 1-year. Recurrence occurred in 3 patients. There was no evidence of CMV resistance. Thirty patients experienced neutropenia within 1-year, 32 were prescribed granulocyte-colony stimulating factors, and 5 experienced thrombocytopenia. Two patients died due to graft-vs-host disease.

CONCLUSION AND RELEVANCE

Low-dose VGC prophylaxis led to comparable CMV infection rates at 6-months in CMV intermediate-risk liver and SLK recipients. However, as SPK recipients displayed higher rates of CMV infection, low-dose VGC should be avoided in this population.

Extended duration letermovir in allogeneic hematopoietic stem cell transplant

OBJECTIVES

Despite the use of antiviral prophylaxis in recipients of allogeneic hematopoietic cell transplants (HCT), cytomegalovirus (CMV) is a common clinically significant infection and is associated with significant morbidity and mortality in this patient population. Based on current approval, letermovir is initiated within 28 days following allogeneic HCT for CMV seropositive recipients and continued through 100 days post-transplant. However, it is unknown whether patients who receive extended duration CMV prophylaxis with letermovir would result in less CMV reactivation and reactivation compared to those who do not. This study aimed to evaluate the efficacy of letermovir prophylaxis in CMV seropositive patients when continued for greater than 100 days post-allogeneic stem cell transplant.

METHODS

A single-center retrospective chart review was conducted on recipients of allogeneic HCT from November 2017 to July 2021. Patients were eligible for inclusion if they were at least 18 years of age, received an allogeneic HCT, CMV seropositive, and initiated letermovir between days 0-28 post-transplant. The primary endpoint of this study is to compare rates of CMV reactivation in patients who stopped letermovir prophylaxis at 100 days post-transplant (standard duration group) versus those who continued letermovir prophylaxis past day 100 (extended duration group).

RESULTS

A total of 87 patients met the eligibility criteria for inclusion. The median duration of letermovir prophylaxis was 78 days in the standard duration group versus and 132 days in the extended duration group. There were more CMV reactivations in the standard duration group versus the extended duration group, 28% versus 19% respectively. CMV pneumonitis was observed in one of the patients in the standard duration group. All-cause mortality at day 200 post-transplant was similar between the two groups.

CONCLUSION

The results of this study suggest that extended duration letermovir prophylaxis may be associated with less CMV reactivation compared to the standard duration of prophylaxis.

Immunoguided Discontinuation of Prophylaxis for Cytomegalovirus Disease in Kidney Transplant Recipients Treated with Antithymocyte Globulin: A Randomized Clinical Trial

BACKGROUND

Antiviral prophylaxis is recommended in cytomegalovirus (CMV)-seropositive kidney transplant (KT) recipients receiving antithymocyte globulin (ATG) as induction. An alternative strategy of premature discontinuation of prophylaxis after CMV-specific cell-mediated immunity (CMV-CMI) recovery (immunoguided prevention) has not been studied. The aim of this study was to evaluate whether it is effective and safe to discontinue prophylaxis when CMV-CMI is detected and to continue with preemptive therapy.

METHODS

In this open-label, non-inferiority clinical trial, patients were randomized 1:1 to follow immunoguided strategy, receiving prophylaxis (valganciclovir 900 mg daily) until CMV-CMI recovery or to receive fixed-duration prophylaxis until day +90. After prophylaxis, preemptive therapy (valganciclovir 900 mg twice daily) was indicated in both arms until month 6. The primary and secondary outcomes were incidence of CMV disease and replication, respectively, within the first 12 months. Desirability of outcome ranking (DOOR) assessed two deleterious events (CMV disease/replication and neutropenia).

RESULTS

A total of 150 CMV-seropositive KT recipients were randomly assigned. There was no difference in the incidence of CMV disease (0% vs. 2.7%; P = 0.149) and replication (17.1% vs. 13.5%; log-rank test, P = 0.422) between both arms. Incidence of neutropenia was lower in the immunoguided arm (9.2% vs. 37.8%; OR, 6.0; P < 0.001). A total of 66.1% of patients in the immunoguided arm showed a better DOOR, indicating a greater likelihood of a better outcome.

CONCLUSIONS

Prophylaxis can be prematurely discontinued in CMV-seropositive KT patients receiving ATG when CMV-CMI is recovered since no significant increase in the incidence of CMV replication or disease is observed.

The Management of Immunosuppression in Kidney Transplant Recipients with COVID-19 Disease: An Update and Systematic Review of the Literature

Background and Objectives: In the era of the coronavirus disease 2019 (COVID-19) pandemic, the management of immunosuppressive (IS) therapy in kidney transplant (KT) recipients affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires attention. It is not yet understood whether IS therapy may protect from the cytokine storm induced by SARS-CoV-2 infection or a temporary adjustment/withdrawal of IS therapy to restore the immune system may be necessary. We performed a systematic literature review to investigate the current management of IS therapy in KT recipients with COVID-1. Materials and Methods: Out of 71 articles published from 1 February 2020 until 30 October 2020, 554 KT recipients with SARS-CoV-2 infection were identified. Results: Modifications of IS therapy were based on the clinical conditions. For asymptomatic patients or those with mild COVID-19 symptoms, a "wait and see approach" was mostly used; a suspension of antimetabolites drugs (347/461, 75.27%) or mTOR inhibitors (38/48, 79.2%) was adopted in the majority of patients with symptomatic COVID-19 infections. For CNIs, the most frequent attitude was their maintenance (243/502, 48.4%) or dose-reduction (99/502, 19.72%) in patients asymptomatic or with mild COVID-19 symptoms, while drug withdrawal was the preferred choice in severely symptomatic patients (160/450, 31.87%). A discontinuation of all IS drugs was used only in severely symptomatic COVID-19 patients on invasive mechanical ventilation. Renal function remained stable in 422(76.17%) recipients, while 49(8.84%) patients experienced graft loss. Eight (1.44%) patients experienced a worsening of renal function. The overall mortality was 21.84%, and 53(9.56%) patients died with functioning grafts. Conclusion: A tailored approach to the patient has been the preferred strategy for the management of IS therapy in KT recipients, taking into account the clinical conditions of patients and the potential interactions between IS and antiviral drugs, in the attempt to balance the risks of COVID-19-related complications and those due to rejection or graft loss.

Overview of Human Cytomegalovirus Pathogenesis

Human cytomegalovirus (HCMV) is a betaherpesvirus with a global seroprevalence of 60-90%. HCMV is the leading cause of congenital infections and poses a great health risk to immunocompromised individuals. Although HCMV infection is typically asymptomatic in the immunocompetent population, infection can result in mononucleosis and has also been associated with the development of certain cancers, as well as chronic inflammatory diseases such as various cardiovascular diseases. In immunocompromised patients, including AIDS patients, transplant recipients, and developing fetuses, HCMV infection is associated with increased rates of morbidity and mortality. Currently there is no vaccine for HCMV and there is a need for new pharmacological treatments. Ongoing research seeks to further define the complex aspects of HCMV pathogenesis, which could potentially lead to the generation of new therapeutics to mitigate the disease states associated with HCMV infection. The following chapter reviews the advancements in our understanding of HCMV pathogenesis in the immunocompetent and immunocompromised hosts.

Pretransplant CMV-Specific T-Cell Immunity But Not Dose of Antithymocyte Globulin Is Associated With Recovery of Specific Immunity After Kidney Transplantation

BACKGROUND

This is a prospective, multicenter, observational study in cytomegalovirus (CMV)-seropositive kidney transplant recipients with pretransplant CMV-specific cell-mediated immunity (CMV-CMI) receiving antithymocyte globulin (ATG). We aimed to investigate posttransplant CMV-CMI over time and the impact of the dose-dependent ATG.

METHODS

CMV-CMI was assessed at days +30, +45, +60, and +90 after transplantation with the QuantiFERON-CMV assay. A reactive result (interferon-γ [IFN-γ] ≥ 0.2 IU/mL) indicated a positive CMV-CMI.

RESULTS

A total of 78 positive CMV-CMI patients were enrolled in the study, of which 59.5% had a positive CMV-CMI at day +30 and 82.7% at day +90. Multivariate logistic regression analysis showed that ATG dose was not associated with positive CMV-CMI at any point. However, pretransplant IFN-γ level (>12 IU/mL vs ≤12 IU/mL) was associated with positive CMV-CMI at day +30 (odds ratio, 12.9; 95% confidence interval, 3.1-53.3; P < .001). In addition, all the patients who did not recover CMV-CMI at day +90 had a pretransplant IFN-γ level ≤12 IU/mL.

CONCLUSIONS

More than half of CMV-seropositive kidney transplant recipients receiving ATG recover (or maintain) CMV-CMI by the first month after transplantation. The pretransplant IFN-γ level, but not the ATG dose, shows a strong association with the kinetics of this recovery.

Polyomavirus and cytomegalovirus infections are risk factors for grafts loss in simultaneous pancreas and kidney transplant

BACKGROUND

Published literature on predictors of polyomavirus (BKV) and cytomegalovirus (CMV) infections in simultaneous pancreas and kidney (SPK) transplant and their impact on allograft outcomes remain sparse. We hypothesize that BKV and CMV viremia infections decrease allograft survival in SPK. Identifying modifiable predictors of BKV and CMV may help tailor immunosuppression and improve allograft survival.

METHODS

All SPK recipients at our institution between January 2000 and April 2016 were included (n = 757). Thirty-nine recipients had BKV only and 25 had CMV only, and infection occurred at median follow-up times of 217 and 163 days, respectively. Event density sampling was used to match recipients with BKV or CMV to up to 10 recipients without infection by age, sex, and HLA mismatch status, and these were followed for a median of 4.3 years after infection.

RESULTS

Older age (HR 1.49 for each decade; 95% CI: 0.95, 2.35; P = .083) and tacrolimus use (HR 20.6; 95% CI: 2.37, 179.53; P = .006) were associated with increased incidence of BKV, but not CMV, infection. Both BKV and CMV infections were associated with increased risk of allograft failure for both pancreas (BKV [HR 2.17; 95% CI 1.47, 3.208; P = .000], CMV [HR 1.7; 95% CI 1.077, 2.687; P = .023]) and kidney (BKV [HR 2.65; 95% CI 1.765, 3.984; P = .000], CMV [HR 2.07; 95% CI 1.295, 3.308; P = .002]).

CONCLUSION

Older age at time of transplant and tacrolimus may help predict BKV infection in SPK recipients.

A randomized, phase 2 study of ASP0113, a DNA-based vaccine, for the prevention of CMV in CMV-seronegative kidney transplant recipients receiving a kidney from a CMV-seropositive donor

Cytomegalovirus (CMV) is a latent infection in most infected individuals, but can be pathogenic in immunocompromised kidney transplant recipients. ASP0113 is a DNA-based vaccine for the prevention of CMV-related mortality and end-organ disease in transplant recipients. The efficacy, safety, and immunogenicity of ASP0113 was assessed in a phase 2, double-blind, placebo-controlled study in CMV-seronegative kidney transplant recipients receiving a kidney from a CMV-seropositive donor. Transplant recipients were randomized (1:1) to receive 5 doses of ASP0113 (5 mg; n = 75) or placebo (n = 74) on Days 30/60/90/120/180 posttransplant, and they received prophylactic valganciclovir/ganciclovir 10-100 days posttransplant. The primary endpoint was the proportion of transplant recipients with CMV viremia ≥1000 IU/mL from Day 100 through to 1 year after the first study vaccine injection. There was no statistically significant difference in the primary endpoint between the ASP0113 and placebo groups (odds ratio 0.79, 95% confidence interval 0.43-1.47; P = .307). There were similar numbers of transplant recipients with treatment-emergent adverse events between groups; however, more transplant recipients reported injection site pain in the ASP0113 group compared with placebo. ASP0113 did not demonstrate efficacy in the prevention of CMV viremia in this CMV-seronegative kidney transplant population, but demonstrated a safety profile similar to placebo. ClinicalTrials.gov registration number: NCT01974206.

Kinetic of the CMV-specific T-cell immune response and CMV infection in CMV-seropositive kidney transplant recipients receiving rabbit anti-thymocyte globulin induction therapy: A pilot study

BACKGROUND

Some studies have suggested that rATG treatment may be associated with an increased incidence of CMV infection and delayed CMV immune response. However, the evidences supporting this matter are scarce. This study aims to characterize the kinetic of the CMV-specific T-cell immune response before and after rATG induction therapy and the relationship with the development of CMV infection in CMV-seropositive kidney transplant recipients.

METHODS

An observational prospective study of CMV-seropositive kidney transplant patients that received rATG induction therapy was performed. A pretransplant sample was obtained before the surgery to determine the CMV-specific immunity. CMV viral load (by PCR) and CMV-specific T-cell immune response (by flow cytometry) were determined during the follow-up at 0.5, 1, 2, 3, 6, and 12 months post transplantation.

RESULTS

A total of 23 patients were included in the study. CMV prophylaxis was administrated for a media of 90 days after transplantation. At the end of follow-up, 18 (78.3%) patients had CMV-specific immunity with a median value of 0.31% CD8⁺ CD69⁺ INF-γ⁺ T cells at a median of 16 weeks post transplantation. Five patients never acquired CMV-specific immunity. No statistically significant association between CMV infection and CMV-specific T-cell immune response (P = .086) was observed. However, patients with positive pretransplant CMV-specific immunity developed earlier immunity and achieved higher levels of CD8⁺ CD69⁺ INF-γ+ T-cell post-transplantation than patients with negative pretransplant immunity.

CONCLUSIONS

CMV-specific immune monitoring in addition to CMV-serology may be useful to stratify patient's risk of CMV infection before transplantation.

Valganciclovir Dosing for Cytomegalovirus Prophylaxis in Pediatric Solid-organ Transplant Recipients: A Prospective Pharmacokinetic Study

BACKGROUND

Valganciclovir is extensively used for prophylaxis and treatment of cytomegalovirus (CMV) infection in solid-organ transplant recipients. However, pharmacokinetic data in children are scarce, and the pediatric dosing regimen is uncertain. This study sought to prospectively evaluate the pharmacokinetic profile, the clinical efficacy and safety of oral valganciclovir in pediatric transplant recipients and compare different dosing regimens.

METHODS

The cohort included solid-organ transplant recipients treated with valganciclovir for CMV prophylaxis in 2014-2015 at a tertiary pediatric medical center. All received a weight-based once-daily oral dose of 17 mg/kg. Ganciclovir concentrations were measured and the area under the curve (AUC0-24) was calculated.

RESULTS

Thirteen children of median age 7.3 years (interquartile range, 2.2-11.6) were included. Median ganciclovir AUC0-24 was 21.0 mcg·h/mL (interquartile range, 17.1-39.8); 10 patients (77%) attained AUC0-24 <40 mcg·h/mL. Exposure to ganciclovir was about 2-fold lower in young children (<9 years old; P = 0.01) and children with low body surface area (BSA; <0.7 m; P = 0.006) than in their counterparts. Significantly lower doses were recommended with our weight-based protocol than with the manufacturer-recommended BSA- and glomerular filtration rate-based protocol (P = 0.002), reaching a 3-fold difference in infants. No evidence of CMV viremia or disease was observed while prophylaxis was given.

CONCLUSIONS

The weight-based regimen of 17 mg/kg/dose oral valganciclovir results in relatively low ganciclovir exposure, especially in young children with low BSA, yet showed satisfactory clinical efficacy for CMV prophylaxis. The manufacturer's dosing recommendation appears to result in supratherapeutic ganciclovir concentrations. Further studies are needed to establish target AUCs and valganciclovir dosing for CMV prophylaxis in pediatric transplant recipients.

Lack of Cytomegalovirus Transmission after Pancreatic Islet Transplantation

In spite of antiviral prophylaxis, the transmission rate of cytomegalovirus (CMV) after solid organ transplantation remains high. In contrast, CMV transmission has never been reported following pancreatic islet transplantation (PIT). Eleven (seven CMV seronegative, four CMV seropositive) recipients underwent a total of 26 PITs. Following PIT recipients were monitored clinically and tested monthly for CMV antigenemia. Valganciclovir was given to all patients for 100 days after each PIT. Follow-up ranged from 6 to 24 months (median 14.5 months). Pancreatic islet grafts were procured from 18 CMV seropositive and 8 seronegative donors (69% and 31% of donors, respectively). In total there were 6 R+D+, 3 R+D-, 12 R-D+, and 5 R-D-PITs. No patient developed CMV antigenemia or symptoms consistent with CMV infection at any time following PIT. Routine posttransplant testing of PIT recipients demonstrated that neither CMV transmission nor CMV infection occurred after PIT.

Molecular Mechanism of Drug Resistance

The treatment of microbial infections has suffered greatly in this present century of pathogen dominance. Inspite of extensive research efforts and scientific advancements, the worldwide emergence of microbial tolerance continues to plague survivability. The innate property of microbe to resist any antibiotic due to evolution is the virtue of intrinsic resistance. However, the classical genetic mutations and extrachromosomal segments causing gene exchange attribute to acquired tolerance development. Rampant use of antimicrobials causes certain selection pressure which increases the resistance frequency. Genomic duplication, enzymatic site modification, target alteration, modulation in membrane permeability, and the efflux pump mechanism are the major contributors of multidrug resistance (MDR), specifically antibiotic tolerance development. MDRs will lead to clinical failures for treatment and pose health crisis. The molecular mechanisms of antimicrobial resistance are diverse as well as complex and still are exploited for new discoveries in order to prevent the surfacing of “superbugs.” Antimicrobial chemotherapy has diminished the threat of infectious diseases to some extent. To avoid the indiscriminate use of antibiotics, the new ones licensed for use have decreased with time. Additionally, in vitro assays and genomics for anti-infectives are novel approaches used in resolving the issues of microbial resistance. Proper use of drugs can keep it under check and minimize the risk of MDR spread.

Effect of long-term prophylaxis in the development of cytomegalovirus-specific T-cell immunity in D+/R- solid organ transplant recipients

BACKGROUND

This study aimed to characterize the dynamics of acquisition of cytomegalovirus (CMV)-specific cell-mediated immunity (CMI) in CMV donor positive/recipient negative solid organ transplant (SOT) patients receiving long-term antiviral prophylaxis, and to determine whether development of CMI confers protection against CMV disease.

METHODS

A prospective multicenter study was conducted in Spain from September 2009 to September 2012. Whole blood specimens were prospectively collected at 30, 90, 120, 200, and 365 days after SOT, and CMI was determined by enumeration of CMV pp65 and IE-1-specific CD69(+) /interferon-γ-producing CD8(+) and CD4(+) T cells by flow cytometry for intracellular cytokine staining. As part of a simultaneous clinical trial, patients received either early prophylaxis (in the first 3 days after transplantation) in the first period of the study or delayed prophylaxis (initiated at day 14) during the second period of the study. The impact of the dynamics of acquisition of CMV-specific CMI on the incidence of CMV disease was evaluated by Kaplan-Meier survival analysis.

RESULTS

A total of 95 SOT recipients were recruited. CMV infection and disease occurred in 38 (40%) and 26 (27.4%) patients, respectively. The proportion of patients achieving any detectable CMV-specific CMI response at each of the different monitoring points was higher in liver transplant recipients, as compared to kidney or heart transplant recipients. The presence of any detectable response at day 120 or 200 was protective against the development of CMV disease (positive predictive values 92% and 93%, respectively).

CONCLUSIONS

The rate of acquisition of CMV-specific CMI in SOT recipients undergoing antiviral prophylaxis differed significantly between different SOT populations. Patients developing any detectable CMI response were protected against the occurrence of CMV disease.

Effect of delaying prophylaxis against CMV in D+/R- solid organ transplant recipients in the development of CMV-specific cellular immunity and occurrence of late CMV disease

OBJECTIVES

Evaluate the protective effect against late CMV disease of delaying antiviral prophylaxis initiation in D+/R- patients receiving solid organ transplant (SOT).

METHODS

Prospective multicenter study in D+/R- SOT recipients in Spain (Sept/09-Sept/12). Whole blood specimens were prospectively collected after Tx for CMV-specific cell-mediated immunity (CMI) determination. Two prophylaxis strategies were compared: early prophylaxis (EP; starting within the first 3 days after Tx) and delayed prophylaxis (DP; starting 14 days after Tx). Risk factors for the occurrence of CMV disease were determined by survival analysis and proportional risk Cox regression models.

RESULTS

We included 95 patients (50 EP V 45 DP). Twenty six patients (27.4%) developed CMV disease: 32.7% EP vs. 20% DP; (p = 0.2). No cases of CMV disease were reported previously to beginning delayed prophylaxis. The percentage of individuals with detectable CMI response was higher in patients with DP although differences did not reach statistic significance (42% vs 29.6% at day 200 after Tx; p = 0.4). There was a clear trend towards less end-organ CMV disease in patients receiving DP (18.2% EP vs 5% DP; p = 0.09) and DP was the only protective factor in the multivariate analysis (HR: 0.26; CI: 0.05-1.2; p = 0.09).

CONCLUSIONS

A 14-day delay in CMV prophylaxis in D+/R- SOT recipients is safe and may reduce the incidence of late CMV end-organ disease although correlation of this effect with CMI responses was not complete.

Population pharmacokinetics of valganciclovir prophylaxis in paediatric and adult solid organ transplant recipients

AIM

Our aims were to quantify ganciclovir pharmacokinetics in paediatric and adult kidney, liver and lung transplant patients taking a range of valganciclovir doses to prevent herpes virus infections, including a 450 mg regimen, and to identify sources of pharmacokinetic variability.

METHOD

Plasma samples were collected at 2, 4, 8 and 12 weeks post-transplant and at 4, 6, 8 and 12 months post-transplant in subjects prescribed longer courses. Ganciclovir was measured by liquid chromatography/ultraviolet detection. Non-linear mixed effects modelling was used to analyze the concentration-time data and evaluate demographic and transplant-related covariates.

RESULTS

A two compartment model with first order absorption best described the data. Given the range of body sizes, clearance and volume of distribution terms were scaled using standard weight-based allometric exponents. Creatinine clearance was included on apparent oral clearance. Final estimates in a standard 70 kg individual for apparent oral clearance, central volume of distribution, intercompartmental clearance and peripheral volume of distribution were 14.5 l h(-1) , 87.5 l, 4.80 l h(-1) and 42.6 l, respectively. The median terminal half-life for kidney, liver and lung transplant recipients was 9.4, 9.5 and 8.2 h, respectively. Median exposure (i.e. AUC(0,∞) in subjects taking valganciclovir 900 mg or 450 mg once daily was 57.4 and 34.3 μg ml(-1)  h, respectively.

CONCLUSION

Allometric scaling allowed simultaneous analysis of data from children and adults. Ganciclovir pharmacokinetics were similar among kidney, liver and lung transplant recipients. Ganciclovir exposure after valganciclovir 450 mg once daily may be suboptimal in some individuals and requires evaluation along with virologic outcomes data.

Valganciclovir for the prevention and treatment of cytomegalovirus disease in immunocompromised hosts

Valganciclovir (Valcyte, Roche), a prodrug of the deoxyguanosine analog ganciclovir (Cytovene, Roche), is indicated for induction and maintenance treatment of cytomegalovirus retinitis in patients with AIDS and for prevention of cytomegalovirus disease in selected high-risk solid organ transplant recipients. After oral administration, valganciclovir is rapidly absorbed and converted to ganciclovir by intestinal and hepatic esterases. Valganciclovir is a highly recognized substrate of the intestinal peptide transporter PEPT1, which underlies the tenfold higher bioavailability of ganciclovir after valganciclovir compared to oral ganciclovir administration. At oral dose of 900 mg, valganciclovir provides a systemic ganciclovir exposure that is comparable to intravenous ganciclovir, at the standard dose of 5 mg/kg of body weight. Subsequent phosphorylation of ganciclovir, which occurs preferentially within cytomegalovirus-infected cells, results in the active metabolite, ganciclovir triphosphate, which is responsible for suppressing viral DNA synthesis by competitively inhibiting the incorporation of the natural substrate deoxyguanosine into viral DNA and thereby, terminating cytomegalovirus replication.

Overview of human cytomegalovirus pathogenesis

Human cytomegalovirus (HCMV) is a human pathogen that infects greater than 50 % of the human population. HCMV infection is usually asymptomatic in most individuals. That is, primary infection or reactivation of latent virus is generally clinically silent. HCMV infection, however, is associated with significant morbidity and mortality in the immunocompromised and chronic inflammatory diseases in the immunocompetent. In immunocompromised individuals (acquired immune deficiency syndrome and transplant patients, developing children (in utero), and cancer patients undergoing chemotherapy), HCMV infection increases morbidity and mortality. In those individuals with a normal immune system, HCMV infection is also associated with a risk of serious disease, as viral infection is now considered to be a strong risk factor for the development of various vascular diseases and to be associated with some types of tumor development. Intense research is currently being undertaken to better understand the mechanisms of viral pathogenesis that are briefly discussed in this chapter.

Successful Embolization of a Cytomegalovirus-Related Duodenal Ulcer in a Kidney-Pancreas Transplant Recipient

One of the complications that can occur in pancreas transplant is a massive intestinal hemorrhage, although such a hemorrhage is very rarely caused by ulcers due to cytomegalovirus infection. Treatment is fundamentally based on relaparatomy, although in some cases interventional radiology can be an efficient alternative because it allows the exact bleeding point to be located and therapeutic embolization to be performed. In this case, a man with diabetes type 1 who was given a simultaneous kidney-pancreas transplant had an ulcer due to cytomegalovirus infection develop in the duodenal graft (in the early postoperative period), causing a severe hemorrhage in the lower part of the gastrointestinal tract that was controlled via selective embolization of a branch of the pancreaticoduodenal artery.

Cytomegalovirus infection post-pancreas-kidney transplantation--results of antiviral prophylaxis in high-risk patients

BACKGROUND

Cytomegalovirus (CMV) is a major pathogen affecting solid organ transplant (SOT) recipients. Prophylactic strategies have decreased the rate of CMV infection/disease among SOT. However, data on the effect of current prophylactic strategies for simultaneous pancreas-kidney (SPK) or pancreas after kidney (PAK) transplant remain limited. We report our experience of CMV prophylaxis in SPK/PAK recipients.

METHODS

A total of 130 post-SPK/PAK patients were analyzed retrospectively for the rate of CMV and the risk factors associated with the acquisition of CMV. All patients received antiviral prophylaxis. The follow-up period was one yr post-transplant or until death.

RESULTS

The rate of CMV post-SPK/PAK transplant was 24%, 44%, and 8.2% among the whole cohort, the D+/R- and the R+ groups, respectively. Median time of prophylaxis was 49 (0-254) d. In the whole cohort, risk factors for CMV infection/diseases were D+/R- CMV status (odds ratio [OR] = 16.075), preceding non-CMV (infection caused by bacteria or fungi and other viruses) infection (OR = 6.362) and the duration of prophylaxis (OR = 0.984). Among the CMV D+/R- group, non-CMV infection was the only risk factor for CMV disease (OR = 10.7).

CONCLUSIONS

Forty-four per cent (25/57) of the D+/R- recipients developed CMV infection/disease despite CMV prophylaxis. Current CMV prophylaxis failed to prevent CMV infection/disease in this group of patients.

Risk of cytomegalovirus disease in high-risk liver transplant recipients on valganciclovir prophylaxis: a systematic review and meta-analysis

Valganciclovir (VGC) was approved by the Food and Drug Administration in 2004 as cytomegalovirus (CMV) prophylaxis except for liver transplant recipients because of their high incidence of CMV disease with this drug. However, surveys have shown its common off-label use for CMV prophylaxis in liver transplant recipients. We aimed to evaluate the risk of CMV disease with VGC prophylaxis in liver transplant recipients. All studies that evaluated liver transplant recipients and used VGC (900 or 450 mg daily) for the prevention of CMV disease were included. Five controlled studies (n = 483) were pooled with a random effects model; five single-arm studies (n = 380) were pooled for the prevalence rate of CMV disease. The risk of CMV disease with VGC versus ganciclovir was 1.81 [95% confidence interval (CI) = 1.00-3.29, P = 0.05, I(2) = 0%]. For high-risk (donor-positive/recipient-negative) patients, the risk of CMV disease was 1.96 (95% CI = 1.05-3.67, P = 0.035, I(2) = 0%). The risk of CMV disease remained significant with 900 mg of VGC daily (P = 0.04) but not with 450 mg of VGC daily (P = 0.76). The risk of leukopenia with VGC was 1.87 (95% CI = 1.03-3.37, P = 0.04, I(2) = 0%). In single-arm trials, the overall CMV disease rate was 12% (95% CI = 9%-16%, P < 0.001), and the rate for high-risk patients was 20% (95% CI = 10%-38%, P = 0.002). In conclusion, 900 mg of VGC daily may not be safe as CMV prophylaxis in high-risk liver transplant recipients because of the significant 2-fold increase in the risk of CMV disease and the 1.9-fold increase in the risk of leukopenia. Alternative CMV prophylaxis should be used for liver transplant recipients.

The value of pre-emptive therapy for cytomegalovirus after liver transplantation

BACKGROUND

Cytomegalovirus (CMV) infections are among the most common infections following liver transplantation. The main preventive methods for CMV infections are universal prophylaxis and pre-emptive therapy. In our study, we adopted a pre-emptive strategy in a higth-risk group of donor CMV-positive (D+)/recipient CMV-negative (R-) casses. We investigated whether this strategy was safe and effective to prevent CMV disease.

METHODS

One hundred fifty-nine liver transplantation recipients who underwent over a 15-year period were retrospectively analyzed after follow-up for at least 6 months (mean, 63 months). Weekly quantitative polymerase chain reaction (PCR) measurements were performed to detect viral DNA. No CMV drug prophylaxis was given: antiviral CMV therapy was initiated when the PCR for CMV-DNA was >400 copies/mL.

RESULTS

Fifty-one of 159 liver transplant recipients enrolled in the study received antiviral therapy. High-risk patients (D+/R-) developed CMV infections significantly more often than D-/R- serostatus (P = .005). CMV disease was diagnosed in 12% of CMV-positive patients. Independent of serostatus in 14 cases (27.5%) virological recurrence of CMV infection occurred after primary treatment. Survival analysis showed no significant difference between patients with versus without CMV infection (P = .950). No relationship could be found between transplant rejection and CMV infection (P = .349).

CONCLUSION

Our results showed that a pre-emptive strategy to prevent CMV disease was possible, even among the serological high-risk group. Only 12% of cases with CMV infection went on to manifest CMV disease with organ involvement. Survival curves were similar among patients with versus without CMV infections.

Six-month low-dose valganciclovir prophylaxis in cytomegalovirus D+/R- kidney transplant patients receiving thymoglobulin induction

BACKGROUND

The use of T-cell-depleting antibody, such as thymoglobulin, is a risk factor for cytomegalovirus (CMV) infection. We studied the effectiveness of 6 months of low-dose valganciclovir prophylaxis in CMV-naive kidney transplant recipients of CMV-positive donor kidney (D+/R-) receiving thymoglobulin induction.

METHODS

We included all D+/R- kidney transplant patients between October 2005 and December 2010 who received valganciclovir 450 mg daily for 6 months as per center protocol. CMV infection was confirmed by positive viremia. Kaplan-Meier and multivariate Cox proportional regression analyses were employed to compare the risk of CMV infection between patients with and without the use of thymoglobulin induction.

RESULTS

Out of 170 D+/R- kidney transplant patients, 42 cases of CMV infection (24.6%) were diagnosed after a median follow-up of 3.2 years: six patients from the noninduction (9.4%) and 36 from the induction cohort (34.0%). The induction with thymoglobulin was associated with four times greater risk of developing CMV infection (adjusted hazard ratio: AHR 4.15, 95% 1.75, 9.86, P = .001). The use of thymoglobulin was associated with leukopenia but not neutropenia.

CONCLUSIONS

Additional measures are needed to reduce the elevated incidence of CMV infection in D+/R- kidney transplant patients receiving induction with thymoglobulin.

Epidemiology of cytomegalovirus infection after pancreas transplantation

BACKGROUND

Epidemiology of cytomegalovirus (CMV) infection has not been comprehensively studied after all three types of pancreas transplant (PT) including simultaneous pancreas-kidney transplantation (SPK), pancreas transplantation alone (PTA), and pancreas after kidney transplantation (PAK).

METHODS

We evaluated incidence, risk factors, and outcomes of CMV infection after pancreas transplant at our center from January 1, 1998, to December 31, 2009.

RESULTS

The study cohort included 252 recipients (SPK 60, PTA 71, and PAK 121), 53% men, age 43.9±9 years, followed for 6.3 (interquartile range 3-9) years. CMV serostatus was donor (D) seropositive and recipient (R) seronegative (D+/R-) (27%), D+/R+ (32%), D-/R+ (18%), D-/R- (23%), and one unknown/R+ (0.4%). Two hundred six (82%) patients received CMV prophylaxis. Twelve patients experienced CMV viremia, whereas 31 developed CMV disease. The cumulative incidence of CMV infection (viremia and disease) was 15%, 17%, and 20% at 1, 5, and 10 years, respectively, with no events after 10 years. It was higher in D+/R- group (P<0.004) and patients with kidney graft failure (P=0.036). The variables significantly associated with pancreas graft failure were transplant type (PTA vs. SPK, hazard ratio [HR]=2.29, P=0.020; PAK vs. SPK, HR=2.73, P=0.003) and acute pancreas rejection (HR=2.47, P<0.001). In multivariable mortality model, increased age (P<0.001) and pancreas graft failure (P<0.001) were associated with an increased risk of death, whereas CMV infection (P=0.036) was associated with a borderline decreased risk.

CONCLUSIONS

CMV remains a common cause of clinical illness, particularly among the CMV D+/R- mismatched and patients with kidney graft failure. Marginal association was observed between CMV infection and a lower risk of death, but not with allograft failure.

Impact of cytomegalovirus disease in D+/R- kidney transplant patients receiving 6 months low-dose valganciclovir prophylaxis

Late-onset cytomegalovirus (CMV) disease remains common in CMV serology naïve kidney transplant patients of CMV serology positive organs (D+/R-) despite the use of antiviral prophylaxis. We studied clinical efficacy of 6-month low-dose valganciclovir (VGCV) prophylaxis, risk factors for late-onset CMV disease and its impact on kidney transplant outcomes. Between October 2005 and December 2009, 166 consecutive D+/R- kidney alone and simultaneous pancreas and kidney transplant patients received VGCV 450 mg daily for 6 months after transplantation. After a median follow-up of 3.2 years, 30 cases of CMV disease occurred within the first 2 years after transplantation with a cumulative incidence of 11.5 and 18.1% at 1 and 2 years, respectively. The use of an induction agent with rabbit antithymocyte globulin and older donor age were factors associated with the risk of late-onset CMV disease (AHR 2.91, 95% CI 1.18-7.20, p = 0.021 and AHR 1.03, 95% CI 1.01-1.06, p = 0.016, respectively). Late-onset CMV disease was associated with increased risk for death-uncensored graft loss (AHR 2.95, 95% CI 1.15-7.61, p = 0.025). In conclusion, late-onset CMV disease continues to negatively impact kidney transplant outcome despite 6-month low-dose VGCV prophylaxis. Investigations focusing on novel preventive approaches should be emphasized.

Risk factors for late-onset cytomegalovirus disease in donor seropositive/recipient seronegative kidney transplant recipients who receive antiviral prophylaxis

BACKGROUND

Cytomegalovirus (CMV) disease occurs frequently after cessation of antiviral prophylaxis in CMV-seronegative kidney transplant recipients from seropositive donors (D+R-), and the risk factors are incompletely defined.

METHOD

We retrospectively assessed the incidence, clinical features, and risk factors for CMV disease in a cohort of D+R- kidney transplant recipients who received antiviral prophylaxis at a single US transplant center using descriptive statistics and Cox proportional hazards models.

RESULTS

CMV disease developed in 29 of 113 (26%) D+R- patients at a median of 185 days (interquartile range 116-231 days) post transplant, including CMV syndrome (66%) and tissue invasive disease (34%). The incidence of CMV disease was higher in patients who underwent re-transplantation (57% vs. 24%) and this factor was independently associated with a higher risk of CMV disease in multivariable analysis (hazard ratio, 4.02; 95% confidence interval, 1.3-13; P = 0.016). Other demographic and transplant variables were not independently associated with a risk of late-onset CMV disease.

CONCLUSIONS

Despite a comprehensive analysis of patient and transplant variables, only re-transplantation was identified as a risk factor for CMV disease in D+R- kidney transplant recipients who received antiviral prophylaxis, but had limited clinical predictive value. The development of novel laboratory markers to identify patients at greatest risk for CMV disease should be a priority for future studies.

Genetic determinants of mycophenolate-related anemia and leukopenia after transplantation

BACKGROUND

Mycophenolate-related anemia and leukopenia are well-known toxicities after transplantation. Toxicity leads to dose reduction, addition of colony-stimulating factors or erythropoietin, or discontinuation of immunosuppressive therapy. The causes of and risk factors associated with toxicity are unclear.

METHODS

We studied the association between mycophenolate-related anemia and leukopenia and 2724 single nucleotide polymorphisms (SNP) in 978 patients undergoing living or deceased donor kidney transplant. Patients were followed up to time of first anemia (hemoglobin<10 gm/dL or hematocrit<30%) or first leukopenia (white blood cell [WBC] count <3000 cells/mm), which required clinical intervention in the first 6 months after transplant.

RESULTS

Anemia occurred in 87 (9.5%) subjects and leukopenia in 224 (22.9%). In single SNP analyses, none of the SNPs were associated with time to leukopenia at a false discovery rate (FDR) of 20%. However, SNPs from the IL12A, HUS, CYP2C8 genes were associated with time to anemia, allowing for an FDR of 20%. To assess the independence of these SNPs as predictors of anemia, we conducted a multi-SNP analysis including one SNP from each of the three genes. All three SNPs were associated with time to anemia, after adjusting for recipient age, weight, posttransplant dialysis and antiviral drug use, and stratifying by clinical center.

CONCLUSION

Although these SNPs require validation in an independent population, our results suggest that genetics may play a role in risk of mycophenolate-related hematologic toxicity. This may ultimately provide for better management of maintenance immunosuppression and gives insights into potential mechanism(s) by which toxicity occurs.

Effectiveness of valganciclovir 900 mg versus 450 mg for cytomegalovirus prophylaxis in transplantation: direct and indirect treatment comparison meta-analysis

BACKGROUND

valganciclovir (VGC) 900 mg is approved for CMV prophylaxis, but it has been associated with 10%-40% leucopenia rate. We hypothesize that VGC 450 mg daily may be as effective as and safer than 900 mg daily.

METHODS

studies evaluating valganciclovir 900 mg and 450 mg daily against controls were evaluated. Direct comparisons were performed by random-effects models and indirect comparisons by the Bucher method.

RESULTS

twelve trials with VGC 900 mg (1543 patients) and 8 trials with VGC 450 mg (1531 patients) were included. The risk of CMV disease with VGC 900 mg versus controls was 1.06 (95% confidence interval [CI], .64-1.76; P = .81; I2=29%) and with VGC 450 mg vs controls .77 (95%CI, .49-1.18; P = .23; I2=24%). The risk of leucopenia was 5.24 (2.09-13.15; P = .0004; I2=44%) for VGC 900 mg versus controls and 1.58 (.96-2.61; P = .07; I2=36%) for VGC 450 mg versus controls; the risk for acute allograft rejection was 1.71 (.45, -6.50; P = .43) for VGC 900 mg and .80 (.50-1.28; P = .34) for VGC 450 mg. Adjusted indirect comparison between VGC 900 mg and VGC 450mg: the risk for CMV disease was not significantly different: odds ratio (OR), 1.38 (.84-2.25); P = .19; the risk of leucopenia was significantly increased with VGC 900 mg: 3.32 (1.76-6.26); P = .0002; and the risk of rejection was significantly increased with VGC 900 mg: 2.56 (1.50-4.53); P = .0005. Results remained consistent after adjustments by allograft, CMV control strategy, and immunosuppression.

CONCLUSIONS

valganciclovir 900 mg showed no superiority efficacy compared to controls (ganciclovir or preemptive) and equivalent efficacy to VGC 450 mg (statistical power: 94% and 97%, respectively) for CMV universal prophylaxis.VGC 900 mg was significantly associated with 3 times increase in the risk of leucopenia and 2 times increase in the risk of rejection compared with VGC 450 mg.

[Cytomegalovirus effects in solid organ transplantation and the role of antiviral prophylaxis]

Cytomegalovirus (CMV) belongs to β-Herpesviridae family. Morbidity related to this infectious agent remains a serious concern in the context of immunosuppression. Occurence of CMV infection within the first 3 months post-renal transplantation without any antiviral prophylaxis is about 70% of patients. Direct and indirect effects of CMV infection in the setting of organ transplantation are described in this review. A 3 to 6 months course of prophylaxis with valganciclovir is advised concerning high-risk transplant recipients (D+/R-) but recommendation regarding intermediate-risk transplant recipients (CMV-seropositive patients) is still unclear. Recent studies highlight a benefit of long time prophylaxis (until 6 months) in terms of CMV disease occurence among D+/R- patients. News assays that measures IFNγ responses to a variety of CMV epitopes (Quantiferon(®) and Elispot IFNγ) are developped to predict CMV disease onset after discontinuation of antiviral prophylaxis. These assays could contribute to adapt prophylaxis to each recipient.

The efficacy and safety of valganciclovir vs. oral ganciclovir in the prevention of symptomatic CMV infection in children after solid organ transplantation

Routine prophylaxis for CMV with valganciclovir is common in adult recipients but data to support its use in children are scarce. The aim of this study was to compare the efficacy and safety of valganciclovir vs. ganciclovir in a pediatric cohort. We performed a retrospective analysis of 92 children after KTx and/or LTx. All children have received IV ganciclovir for two wk, and then oral ganciclovir (TID; n = 41) before 2004, or valganciclovir (OD; n = 51) thereafter. Treatment was given for three months in R+/D+ or R+/D- recipients and for six months in R-/D+. Patients were followed for one yr post transplant. Both groups were comparable in their demographic and transplant-related history. Symptomatic CMV infection/disease developed in 13.7% vs. 19.5% of valganciclovir and ganciclovir groups, respectively (P-NS). Time-to-onset of CMV infection was comparable in both groups (P-NS); rates of acute allograft rejection were similar in both groups (3.9% vs. 9.8%). Risk factors for CMV infection included young age, serostatus of R-/D+, and allograft from cadaver donor. No significant side effects were noted in both groups. As in adults, valganciclovir appears to be as efficacious and safe as oral ganciclovir. Valganciclovir should be considered as a possible prophylactic treatment for CMV in pediatric recipients of KTx or LTx.

Primary CMV infections are common in kidney transplant recipients after 6 months valganciclovir prophylaxis

Prolonging cytomegalovirus (CMV) prophylaxis in CMV seronegative recipients of a kidney from CMV seropositive donor (D+/R-) may reduce the incidence of late infections. We analyzed late-onset primary CMV infections after 6 months valganciclovir prophylaxis. Data from all CMV D+/R- kidney transplant recipients between January 2004 and December 2008 at our center were analyzed. Patients with a functioning graft at 6 months after transplantation who received 6 months of valganciclovir prophylaxis 900 mg once daily were included (N = 127). CMV was diagnosed with quantitative PCR. Prophylaxis was completed in 119 patients. Prophylaxis was stopped at 3-5 months due to leukopenia or gastrointestinal side effects in eight patients. Late-onset primary CMV infection developed in 47/127 (37%) patients median 244 days after transplantation (range 150-655) and median 67 days after the cessation of prophylaxis (range 1-475). Four infections were asymptomatic. In others, symptoms included fever (N = 28), gastrointestinal symptoms (nausea, vomiting, diarrhea) (N = 24), respiratory tract symptoms (N = 12), and hepatopathy (N = 6). Median peak viral load was 13500 copies/mL (range 400-2,831,000). Recurrent CMV infection developed in 9/47 (19%) patients. No significant risk factors for CMV infection were identified. Symptomatic primary CMV infections were commonly detected also after prolonged valganciclovir prophylaxis.

Valganciclovir: recent progress

In 2001 valganciclovir was approved by the FDA for treatment of HIV associated retinitis and in 2003 for prevention of post transplant CMV. This review provides an update on the status of its use and areas of controversy: How long should prophylaxis be given?; What is the appropriate dose for prophylaxis?; Can it be used in children, and at what dose?; Can it be used to treat CMV disease? The question of optimal dosing will probably not be settled as the sample size for controlled trials would be prohibitive. Other trials clearly show that extended therapy provides added benefit, the drug is safe and an appropriate dose has been identified in children and oral therapy of CMV disease is effective.

Defining the risks for cytomegalovirus infection and disease after solid organ transplantation

Cytomegalovirus continues to be one of the most clinically significant infections after solid organ transplantation. Classic definitions of patients at high risk for infection and tissue-invasive disease are focused on recipient-donor serostatus, type of organ transplanted, and overall level of immunosuppression. However, recent trends in clinical practice call for a reevaluation of cytomegalovirus infection risks after solid organ transplantation. Indeed, whereas early-onset cytomegalovirus infection is usually controlled by antiviral prophylaxis with ganciclovir and derivatives, delayed- and late-onset cytomegalovirus infection can develop after the completion of a course of preventive therapy. In addition, indirect effects of cytomegalovirus infection may occur as a result of persistent low-level viremia. Suboptimal dosing of antiviral drugs due to specific drug toxicities may result in the development of ganciclovir-resistant cytomegalovirus disease. The relationship between organ allograft rejection and cytomegalovirus infection and disease has been recognized for some time. Transplantation of increasing numbers of extended-criteria donor organs increases the risk of delayed graft function and acute rejection, prompting the use of more intensive immunosuppression. In addition, the trend to spare long-term exposure to calcineurin inhibitors has contributed to a resurgence in the use of polyclonal T-cell induction immunosuppressive agents, which may reduce host anticytomegalovirus immunity. We discuss the current trends in solid organ transplantation that provide a foundation for defining risks for cytomegalovirus infection and disease, including identification of patients who would benefit from more aggressive cytomegalovirus monitoring and prevention strategies.

Variable viral clearance despite adequate ganciclovir plasma levels during valganciclovir treatment for cytomegalovirus disease in D+/R- transplant recipients

BACKGROUND

Valganciclovir, the oral prodrug of ganciclovir, has been demonstrated equivalent to iv ganciclovir for CMV disease treatment in solid organ transplant recipients. Variability in ganciclovir exposure achieved with valganciclovir could be implicated as a contributing factor for explaining variations in the therapeutic response. This prospective observational study aimed to correlate clinical and cytomegalovirus (CMV) viral load response (DNAemia) with ganciclovir plasma concentrations in patients treated with valganciclovir for CMV infection/disease.

METHODS

Seven CMV D+/R- transplant recipients (4 kidney, 2 liver and 1 heart) were treated with valganciclovir (initial dose was 900-1800 mg/day for 3-6.5 weeks, followed by 450-900 mg/day for 2-9 weeks). DNAemia was monitored by real time quantitative PCR and ganciclovir plasma concentration was measured at trough (Ctrough) and 3 h after drug administration (C3h) by HPLC.

RESULTS

Four patients presented with CMV syndrome, two had CMV tissue-invasive disease after prophylaxis discontinuation, and one liver recipient was treated pre-emptively for asymptomatic rising CMV viral load 5 weeks post-transplantation in the absence of prophylaxis. CMV DNAemia decreased during the first week of treatment in all recipients except in one patient (median decrease: -1.2 log copies/mL, range: -1.8 to 0) despite satisfactory ganciclovir exposure (AUC0-12 = 48 mgxh/L, range for the 7 patients: 40-118 mgxh/L). Viral clearance was obtained in five patients after a median of time of 34 days (range: 28-82 days). Two patients had recurrent CMV disease despite adequate ganciclovir exposure (65 mgxh/L, range: 44-118 mgxh/L).

CONCLUSIONS

Valganciclovir treatment for CMV infection/disease in D+/R- transplant recipients can thus result in variable viral clearance despite adequate ganciclovir plasma concentrations, probably correlating inversely with anti-CMV immune responses after primary infection.

Six-month prophylaxis is cost effective in transplant patients at high risk for cytomegalovirus infection

The risk of late-onset cytomegalovirus (CMV) infection remains a concern in seronegative kidney and/or pancreas transplant recipients of seropositive organs despite the use of antiviral prophylaxis. The optimal duration of prophylaxis is unknown. We studied the cost effectiveness of 6- versus 3-mo prophylaxis with valganciclovir. A total of 222 seronegative recipients of seropositive kidney and/or pancreas transplants received valganciclovir prophylaxis for either 3 or 6 mo during two consecutive time periods. We assessed the incidence of CMV infection and disease 12 mo after completion of prophylaxis and performed cost-effectiveness analyses. The overall incidence of CMV infection and disease was 26.7% and 24.4% in the 3-mo group and 20.9% and 12.1% in the 6-mo group, respectively. Six-month prophylaxis was associated with a statistically significant reduction in risk for CMV disease (HR, 0.35; 95% CI, 0.17 to 0.72), but not infection (HR, 0.65; 95% CI, 0.37 to 1.14). Cost-effectiveness analyses showed that 6-mo prophylaxis combined with a one-time viremia determination at the end of the prophylaxis period incurred an incremental cost of $34,362 and $16,215 per case of infection and disease avoided, respectively, and $8,304 per one quality adjusted life-year gained. Sensitivity analyses supported the cost effectiveness of 6-mo prophylaxis over a wide range of valganciclovir and hospital costs, as well as variation in the incidence of CMV disease. In summary, 6-mo prophylaxis with valganciclovir combined with a one-time determination of viremia is cost effective in reducing CMV infection and disease in seronegative recipients of seropositive kidney and/or pancreas transplants.

A new strategy of delayed long-term prophylaxis could prevent cytomegalovirus disease in (D+/R-) solid organ transplant recipients

Long-term prophylaxis against cytomegalovirus (CMV) started immediately after transplantation in (D+/R-) poses a higher risk of late-onset CMV disease. Delayed CMV prophylaxis could allow a transitory exposure of the immune system to CMV, which would let the immune system mount an adequate CMV-specific cytotoxic response in (D+/R-) patients and confer protection against CMV disease. We included all (D+/R-) solid organ transplant recipients (SOT) performed at our institution (January 3/October 6) who received CMV prophylaxis (mainly with oral valganciclovir) during 100 d. In the first period (until December 4), prophylaxis was initiated immediately after transplantation (conventional prophylaxis: CP). Since January 5, it was initiated after 14 d (delayed prophylaxis: DP). Incidence and severity of CMV disease was compared between both groups. A total of 44 SOT recipients were included (CP: 26 and DP: 18). CMV disease was diagnosed in eight patients (18%), seven of 26 (27%) in the CP group, and one of 18 (5.5%) in the DP group (p = 0.07). CMV colitis was reported in five of 26 patients in the CP group (19%), whereas there were no cases of visceral CMV disease in the DP group (p = 0.048). A 14-d delay in the beginning of long-term prophylaxis against CMV in (D+/R-) is safe and could prevent the onset of late-CMV disease.