Critical analysis of valganciclovir dosing and renal function on the development of cytomegalovirus infection in kidney transplantation

Steroid-tacrolimus drug-drug interaction and the effect of CYP3A genotypes

AIMS

Tacrolimus, metabolized by CYP3A4 and CYP3A5 enzymes, is susceptible to drug-drug interactions (DDI). Steroids induce CYP3A genes to increase tacrolimus clearance, but the effect is variable. We hypothesized that the extent of the steroid-tacrolimus DDI differs by CYP3A4/5 genotypes.

METHODS

Kidney transplant recipients (n = 2462) were classified by the number of loss of function alleles (LOF) (CYP3A5*3, *6 and *7 and CYP3A4*22) and steroid use at each tacrolimus trough in the first 6 months post-transplant. A population pharmacokinetic analysis was performed by nonlinear mixed-effect modelling (NONMEM) and stepwise covariate modelling to define significant covariates affecting tacrolimus clearance. A stochastic simulation was performed and translated into a Shiny application with the mrgsolve and Shiny packages in R.

RESULTS

Steroids were associated with modestly higher (3%-11.8%) tacrolimus clearance. Patients with 0-LOF alleles receiving steroids showed the greatest increase (11.8%) in clearance compared to no steroids, whereas those with 2-LOFs had a negligible increase (2.6%) in the presence of steroids. Steroid use increased tacrolimus clearance by 5% and 10.3% in patients with 1-LOF and 3/4-LOFs, respectively.

CONCLUSIONS

Steroids increase the clearance of tacrolimus but vary slightly by CYP3A genotype. This is important in individuals of African ancestry who are more likely to carry no LOF alleles, may more commonly receive steroid treatment, and will need higher tacrolimus doses.

Challenges for the improvement of valganciclovir prophylaxis in solid organ transplantation and the possible role of therapeutic drug monitoring in adults

Cytomegalovirus (CMV) infection frequently occurs after solid organ transplantation and is associated with an increased morbidity and mortality. Fortunately, the development of valganciclovir prophylaxis has lowered the incidence of CMV infection and its complications in immunosuppressed solid organ transplant recipients. However, breakthrough infections during valganciclovir prophylaxis and late CMV infection after cessation of valganciclovir prophylaxis still occur with the current prophylactic strategy. Additionally, valganciclovir resistance has emerged among CMV strains, which complicates the treatment of CMV infections. Furthermore, the use of valganciclovir is associated with myelotoxicity, which can lead to the premature withdrawal of prophylaxis. It is important to address these current issues in order to improve the standard care after solid organ transplantation. This paper will therefore discuss the clinical practice of valganciclovir prophylaxis, elaborate on its issues and suggest how to improve the current prophylactic strategy with a possible role for therapeutic drug monitoring.

A Systematic Review and Meta-analysis of Optimized CMV Preemptive Therapy and Antiviral Prophylaxis for CMV Disease Prevention in CMV High-Risk (D+R-) Kidney Transplant Recipients

The optimal strategy for cytomegalovirus (CMV) disease prevention in CMV donor/recipient kidney transplant recipients remains uncertain. Conclusions of prior meta-analyses that CMV disease rates with preemptive therapy (PET) and universal prophylaxis (UP) were comparable may have been affected by inclusion of studies lacking key determinants of efficacy of the respective strategies.

Methods

We conducted a systematic review and meta-analysis of PET with weekly CMV polymerase chain reaction monitoring for ≥3 mo and UP with 6 mo of valganciclovir. PubMed and Embase databases were reviewed from January 1, 2010, to April 1, 2022. Risk of bias was assessed with 3 instruments (Cochrane RoB, Cochrane RoBINS-I, and an instrument for assessing risk in observational studies). The primary outcome was CMV disease incidence by 1-y posttransplant. Secondary outcomes by 1-y were graft loss, acute allograft rejection, and mortality. Results were synthesized using generalized linear mixed model meta-analysis. PET studies were stratified into low-threshold (LT) and high-threshold (HT) PET based on the viral load threshold for initiation of antiviral therapy.

Results

Twenty-five studies met inclusion criteria (6 PET, 19 UP). CMV disease incidence was significantly higher in HT (0.30 [95% confidence interval (CI), 0.22-0.39]) versus LT PET (0.06 [95% CI, 0.03-0.12]). LT PET was associated with a significantly lower CMV disease incidence (0.06 [95% CI, 0.03-0.12]) versus UP (0.21 [95% CI, 0.17-0.27]). Incidence of graft loss, acute allograft rejection, or mortality was not significantly different between LT PET and UP (P > 0.05 for all comparisons). Receipt of lymphocyte-depleting antibodies was not associated with a significant difference in CMV disease incidence (odds ratio = 1.34 [95% CI, 0.80-2.25]).

Conclusions

LT PET is associated with a significantly lower incidence of CMV disease compared to UP with similar rates of other clinical outcomes. These findings provide rationale and preliminary data for a randomized superiority trial of optimized LT-PET versus UP in donor seropositive recipient seronegative kidney transplant recipients.

Optimizing ganciclovir and valganciclovir dosing regimens in pediatric patients with cytomegalovirus infection: a spotlight on therapeutic drug monitoring

INTRODUCTION

Infants and immunocompromised children with cytomegalovirus (CMV) infection have significant morbidity and mortality. Ganciclovir (GCV) and its oral prodrug valganciclovir (VGCV) are the major antiviral options of choice for the prophylaxis and treatment of CMV infection. However, with the currently recommended dosing regimens used in pediatric patients, large intra- and inter-individual variability of pharmacokinetic (PK) parameters and exposure are observed.

AREAS COVERED

This review describes the PK and pharmacodynamic (PD) characteristics of GCV and VGCV in pediatrics. Moreover, the role of therapeutic drug monitoring (TDM) and current clinical practice for GCV and VGCV dosing regimens optimization in pediatrics are discussed.

EXPERT OPINION

GCV/VGCV TDM has shown the potential value to improve the benefit/risk ratio in pediatrics when using the therapeutic ranges derived from adults. However, well-designed studies are required to evaluate the relationship of TDM with clinical outcomes. Furthermore, studies to explore the children-specific dose-response-effect relationships will be helpful to facilitate the TDM practice. In the clinical setting, optimal sampling methods such as limited sampling strategies for pediatrics can be used in TDM and intracellular ganciclovir triphosphate may be used as an alternative TDM marker.

Risk factors for cytomegalovirus infection and disease after kidney transplantation: A meta-analysis

OBJECTIVE

To investigate the risk factors for cytomegalovirus (CMV) infection and disease in kidney transplantation recipient, and provide references for the prevention and control of CMV infection and disease in kidney transplantation patients.

METHODS

Chinese and international literature related to risk factors for CMV infection and disease in renal transplant recipients was searched using databases, including China National Knowledge Infrastructure; WanFang Data; Wiper; Chinese Biomedical Literature database; PubMed; Embase; Web of Science, and the Cochrane Register of Controlled Trials. Two researchers independently screened the literature, extracted the data, and evaluated the quality of the literature according to published standards. A meta-analysis was performed using RevMan 5.4 software to extract the risk factors for CMV infection and disease in renal transplant recipients.

RESULTS

A total of 59,847 subjects were included in 24 studies. The risk factors for CMV infection were ATG [OR = 2.76, 95% CI (2.10, 3.63), P < 0.00001], Donor (D) CMV-IgG(+) Receptor (R)(-): (D+/R-) [OR = 2.97, 95% CI (1.63, 5.44), P = 0.004 < 0.05], recipient age [OR = 1.96, 95% CI (1.50, 2.54), P < 0.00001], lymphocytopenia [OR = 3.26, 95% CI (1.46, 7.31), P < 0.00001], and mycophenolate [OR = 3.22, 95% CI (2.02, 5.46), P < 0.00001]. The protective factor for CMV infection was glomerular filtration rate (GFR) [OR = 0.98, 95% CI (0.97, 0.99), P < 0.00001], and the uncertain factors were the use of tacrolimus [OR = 0.91, 95% CI (0.64, 1.28), P = 0.58 > 0.05], rejection [OR = 1.32, 95% CI (0.49, 3.53), P = 0.58 > 0.05], donor age [OR = 1.00, 95% CI (0.99, 1.01), P = 0.67 > 0.5], and preemptive therapy [OR = 0.51, 95% CI (0.11, 2.36), P = 0.86 > 0.05]. The risk factors for CMV disease were D+/R- [OR = 4.78, 95% CI (3.76, 6.07), P < 0.00001], ATG [OR = 1.83, 95% CI (1.25, 2.67), P < 0.00001], rejection [OR = 1.42, 95% CI (1.26, 1.59), P < 0.00001], mycophenolate [OR = 1.67, 95% CI (1.38, 2.02), P < 0.00001], recipient age [OR = 1.03, 95% CI (1.02, 1.03), P < 0.00001], donor age [OR = 1.01, 95% CI (1.00, 1.01), P = 0.001 < 0.05], Donor (D) CMV-IgG(+) Receptor(R)(+): (D+/R+) [OR = 1.92, 95% CI (1.49, 2.46), P < 0.00001], the use of prednisolone [OR = 1.59, 95% CI (1.32, 1.92), P < 0.00001], and diabetes mellitus[OR = 1.18, 95% CI (1.01, 1.37), P = 0.03 < 0.05], and the uncertain factors were donor type [OR = 4.10, 95% CI (0.28, 59.79), P = 0.30 > 0.05], time of transplantation [OR = 0.95, 95% CI (0.78, 1.16), P = 0.64 > 0.05], and the use of cyclosporine [OR = 1.50, 95% CI (0.62, 3.64), P = 0.37 > 0.05].

CONCLUSION

There are many factors influencing CMV infection and disease in kidney transplant patients. Risk factors should be carefully monitored, protective factors strengthened, and more attention paid to uncertain factors.

The Prevalence of Neurological Complication after Renal Transplantation

Objective

To evaluate the incidence of neurological complications (NCs) after renal transplantation by meta-analysis.

Methods

A broad literature search in PubMed, Embase, and Cochrane-Library was performed from inception to December 31, 2021, to collect published studies on the incidence of NCs after kidney transplantation. The R language meta-package was used to organize and analyze the data.

Results

17 articles including 1,1119 participants were considered eligible. There were 3 studies that recorded unclassified NCs (249 participants), 6 that recorded nervous system CMV infection (1489 participants), 3 that recorded headache (243 participants), and 5 that recorded cerebrovascular events (9138 participants). There was significant heterogeneity (all I ² ≥ 75%) in all analyses, and random-effects models were selected. Meta-analysis results showed that the incidence of unclassified NCs was 0.29 (95% CI (0.16-0.48)), the incidence of nervous system CMV infection was 0.38 (95% CI (0.26-0.52)), the incidence of headache was 0.55 (95% CI (0.44-0.66)), and the incidence of stroke was 0.05 (95% CI (0.02-0.09)). Egger's test showed that there was no conspicuous publication bias in the included literature in each group.

Conclusions

Headache had the highest incidence (55%) in the nervous system after KT, followed by nervous system CMV infection (38%) and stroke (5%). Nevertheless, due to the inconsistencies in the types of NCs included and the follow-up time, our results might only serve as an epidemiological reference for the specific incidence differences.

Optimization of Ganciclovir use in allogeneic hematopoietic cell transplant recipients - the role of therapeutic drug monitoring

Introduction: Cytomegalovirus (CMV) is an opportunistic infectious complication that can occur after allogeneic hematopoietic cell transplantation (HCT). The mainstay of treatment and prevention of this infection is ganciclovir and its ester prodrug valganciclovir. There is conflicting evidence on the clinical utility of routine ganciclovir therapeutic drug monitoring (TDM) as a means to optimize treatment.Areas covered: This review aims to describe the current knowledge of the pharmacokinetic and pharmacodynamic characteristics of ganciclovir and valganciclovir, and to explore the evidence and challenges surrounding ganciclovir TDM within the allogeneic HCT cohort.Expert opinion: Ganciclovir TDM is important to optimize efficacy in selected patient groups where there are variable pharmacokinetic factors or inadequate response to treatment. However, defined pharmacokinetic exposures which correlate with treatment efficacy and toxicity remain elusive. Prospective clinical studies in specific patient groups are required to clarify this issue. Alternative TDM targets such as the intracellular ganciclovir triphosphate should be explored as they may prove to have better correlation with clinical outcomes and adverse effects. With recent advances in CMV immune monitoring, novel approaches integrating TDM with specific CMV immune phenotyping in a predictive model will be advantageous in optimizing ganciclovir dosing by combining TDM with a risk stratification approach.

Ganciclovir Dosing Strategies and Development of Cytomegalovirus Resistance in a Kidney Transplant Recipient: A Case Report

In renal transplant recipients, delayed graft function and accompanying renal impairment may lead to therapeutic underexposure of valganciclovir. We describe a case of a cytomegalovirus (CMV)-seronegative kidney transplant recipient from a CMV-seropositive donor, whose course was complicated during valganciclovir prophylaxis by CMV disease, ultimately progressing to ganciclovir, foscarnet, and cidofovir resistance. Assessments and adjustments for renal dysfunction, according to both Cockgroft-Gault and Modification of Diet in Renal Disease study equations, are described. Therapy was complicated by outpatient parenteral therapy with pump-administered antiviral therapy, which may have led to drug underexposure and the fostering of antiviral resistance. Suppression was ultimately achieved in conjunction with reduction in immunosuppressive therapy, CMV immunoglobulin, and initiation of leflunomide. At-risk recipients may benefit from 24 hour creatinine clearance assessments, direct creatinine clearance measurement, or therapeutic drug monitoring. Optimal dosing strategies in recipients with impaired kidney function remain undefined, with limited pharmacokinetic data to date.

Incidence and Risk Factors for Leukopenia in Kidney Transplant Recipients Receiving Valganciclovir for Cytomegalovirus Prophylaxis

Context:

Valganciclovir is used not only for cytomegalovirus prophylaxis after kidney transplantation but can also induce leukopenia, thereby making patients more susceptible to other infections. The epidemiology of leukopenia in patients on valganciclovir remains poorly understood.

Objective:

To determine the incidence and risk factors for leukopenia in patients receiving valganciclovir for cytomegalovirus prophylaxis after kidney transplantation.

Methods:

In this single-center, retrospective, cohort study, we included kidney recipients transplanted from January 1, 2003, to December 31, 2010, to determine the incidence and risk factors for leukopenia in patients who received valganciclovir for cytomegalovirus prophylaxis. The Kaplan-Meier product limit method was used to graphically assess time to leukopenia, and risk factors were assessed using Cox proportional hazards models.

Results:

A total of 542 kidney transplant recipients were included in the study cohort. The cumulative incidence of leukopenia at 6 months posttransplant was 39.3% (11.0% for neutropenia). Low baseline white blood cell count (hazard ratio [HR] 2.34 [95% confidence interval [CI], 1.37-4.00]) and high baseline body mass index (HR 1.05 [95% CI, 1.02-1.09]) were independently associated with an increased risk of leukopenia, while higher Cockcroft-Gault creatinine clearance (HR 0.87 [95% CI, 0.78-0.97]) was significantly associated with a decreased risk of leukopenia.

Conclusions:

These data suggest that recipient baseline white blood cell count, baseline body mass index, and kidney function are clinical predictors of new-onset leukopenia after kidney transplantation. Our results may inform the approach to cytomegalovirus prophylaxis to reduce the risk of valganciclovir-induced leukopenia in kidney transplant recipients.

Impact of electronic health record-based, pharmacist-driven valganciclovir dose optimization in solid organ transplant recipients

BACKGROUND

Prophylaxis with valganciclovir reduces the incidence of cytomegalovirus (CMV) infection following solid organ transplant (SOT). Under-dosing of valganciclovir is associated with an increased risk of CMV infection and development of ganciclovir-resistant CMV.

METHODS

An automated electronic health record (EHR)-based, pharmacist-driven program was developed to optimize dosing of valganciclovir in solid organ transplant recipients at a large transplant center. Two cohorts of kidney, pancreas-kidney, and liver transplant recipients from our center pre-implementation (April 2011-March 2012, n = 303) and post-implementation of the optimization program (September 2012-August 2013, n=263) had demographic and key outcomes data collected for 1 year post-transplant.

RESULTS

The 1-year incidence of CMV infection dropped from 56 (18.5%) to 32 (12.2%, P = .05) and the incidence of breakthrough infections on prophylaxis was cut in half (61% vs 34%, P = .03) after implementation of the dose optimization program. The hazard ratio of developing CMV was 1.64 (95% CI 1.06-2.60, P = .027) for the pre-implementation group after adjusting for potential confounders. The program also resulted in a numerical reduction in the number of ganciclovir-resistant CMV cases (2 [0.7%] pre-implementation vs 0 post-implementation).

CONCLUSIONS

An EHR-based, pharmacist-driven valganciclovir dose optimization program was associated with reduction in CMV infections.

High frequency of valganciclovir underdosing for cytomegalovirus prophylaxis after renal transplantation

Background

The correct valganciclovir dose for cytomegalovirus (CMV) prophylaxis depends on renal function estimated by the Cockcroft–Gault (CG) estimated creatinine clearance (CG-CrCl) formula. Patients with delayed or rapidly changing graft function after transplantation (tx) will need dose adjustments.

Methods

We performed a retrospective investigation of valganciclovir dosing in renal transplant patients receiving CMV prophylaxis between August 2003 and August 2011, and analysed valganciclovir dosing, CG-CrCl, CMV viraemia (CMV-PCR <750 copies/mL), leucopenia (<3500/µL) and neutropenia (<1500/µL) in the first year post-transplant. On Days 30 and 60 post-transplant, dosing pattern in relation to estimated creatinine clearance was analysed regarding CMV viraemia, leucopenia and neutropenia.

Results

Six hundred and thirty-five patients received valganciclovir prophylaxis that lasted 129 ± 68 days with a mean dose of 248 ± 152 mg/day of whom 112/635 (17.7%) developed CMV viraemia, 166/635 (26.1%) leucopenia and 48/635 (7.6%) neutropenia. CMV resistance within 1 year post-transplant was detected in three patients. Only 137/609 (22.6%) patients received the recommended dose, while n = 426 (70.3%) were underdosed and n = 43 (7.1%) were overdosed at Day 30 post-tx. Risk factors for CMV viraemia were donor positive D (+)/receptor negative R (−) status and short prophylaxis duration, but not low valganciclovir dose. Risk factors for developing leucopenia were D+/R− status and low renal function. No significant differences in dosing frequency were observed in patients developing neutropenia or not (P = 0.584).

Conclusion

Most patients do not receive the recommended valganciclovir dose. Despite obvious underdosing in a large proportion of patients, effective prophylaxis was maintained and it was not associated as a risk factor for CMV viraemia or leucopenia.

Treatment of CMV infection after allogeneic hematopoietic stem cell transplantation

Despite a remarkable reduction in the past decades, cytomegalovirus (CMV) disease in allogeneic hematopoietic stem cell transplant (HSCT) recipients remains a feared complication, still associated with significant morbidity and mortality. Today, first line treatment of CMV infection/reactivation is still based on dated antiviral compounds Ganciclovir (GCV), Foscarnet (FOS) and Cidofovir (CDF) with their burdensome weight of side effects. Maribavir (MBV), Letermovir (LMV) and Brincidofovir (BDF) are three new promising anti-CMV drugs without myelosuppressive properties or renal toxic effects that are under investigation in randomized phase II and III trials. Adoptive T-cell therapy (ATCT) in CMV infection possesses a strong rationale, demonstrated by several proof of concept studies; its feasibility is currently under investigation by clinical trials. ATCT from third-party and naïve donors could meet the needs of HSCT recipients of seronegative donors and cord blood grafts. In selected patients such as recipients of T-cell depleted grafts, ATCT, based on CMV-specific host T-cells reconstitution kinetics, would be of value in the prophylactic and/or preemptive CMV treatment. Vaccine-immunotherapy has the difficult task to reduce the incidence of CMV reactivation/infection in highly immunocompromised HSCT patients. Newer notions on CMV biology may represent the base to flush out the Troll of transplantation.

Occurrence of adverse events caused by valganciclovir as pre-emptive therapy for cytomegalovirus infection after allogeneic stem cell transplantation is reduced by low-dose administration

BACKGROUND

Pre-emptive therapy with valganciclovir (VGCV) has become the standard therapy for preventing cytomegalovirus (CMV) infection after allogeneic hematopoietic stem cell transplantation (HSCT). The effectiveness of low-dose VGCV (900 mg per day) has been shown to be equal to that of standard-dose VGCV (900 mg twice daily); however, individualized optimal dosing and toxicity of VGCV have not been reported.

METHODS

We conducted a retrospective study to evaluate the optimal dose of VGCV as pre-emptive therapy for preventing CMV infection by comparing the frequency of adverse events (AEs) and clinical efficacy in a low-dose VGCV group with those in a standard-dose VGCV group. Thirty-eight patients who were administered VGCV because of CMV antigenemia after HSCT were analyzed.

RESULTS

Neutropenia (standard-dose group: 33%, low-dose group: 15%, P = 0.26) and thrombocytopenia (standard-dose group: 39%, low-dose group: 15%, P = 0.14) were frequent AEs of VGCV, and a significantly higher frequency of overall AEs was detected in the standard-dose group than in the low-dose group (P < 0.01). In comparison of dosage based on weight, dosage of VGCV >27 mg/kg was closely related to onset of AEs (P = 0.04).

CONCLUSIONS

Low-dose VGCV was not inferior in clinical efficacy, including clearance rate of CMV antigenemia and incidence of consequent CMV disease, to standard-dose VGCV as was previously reported. Initial low-dose VGCV for pre-emptive CMV therapy markedly reduces hematologic toxicity and has clinical efficacy equivalent to that of standard-dose VGCV. It is therefore reasonable for patients, except for noticeably overweight patients, to be given initial low-dose VGCV.

Value of solid organ transplant-trained pharmacists in transplant infectious diseases

Advances in organ transplantation have led to improved graft and patient survival. Transplant pharmacist's education and training uniquely position them to contribute knowledge and skills to the management of these highly complex patients. In 2004, the United Network for Organ Sharing bylaws added requirements that all transplant programs identify one or more pharmacists with experience in transplant pharmacotherapy to be responsible for providing pharmaceutical care to solid organ transplant recipients. These bylaws also delineated the transplant pharmacist's roles and responsibilities. To further support these efforts, in 2007 the Centers for Medicare and Medicaid Services accreditation standards for transplant centers also mandated that a center have a designated, qualified expert in transplant pharmacology as a multidisciplinary team member. The transplant pharmacist is a consistent member of the transplant team that can add value to the multidisciplinary approach of prevention and treatment of transplant infectious diseases through all phases of transplant care.

Use of leflunomide in renal transplant recipients with ganciclovir-resistant/refractory cytomegalovirus infection: a case series from the University of Chicago

Introduction

Although antiviral prophylaxis for cytomegalovirus (CMV) is widely used, CMV infection remains common in renal transplant recipients with adverse consequences.

Methods

We report 5 cases of renal transplant recipients with resistant CMV infection who were successfully managed with leflunomide at the University of Chicago Medical Center.

Results

Five renal transplant recipients (2 simultaneous pancreas/kidney transplants, 3 deceased donor kidney transplants) were diagnosed with GCV-resistant CMV infection from 2003 to 2011. Of the 4 patients who had resistance genotype testing, 3 showed a UL97 mutation and 1 patient had a clinically resistant CMV infection. All patients received CMV prophylaxis with valganciclovir for 3 months. The number of days from the date of transplant to viremia ranged from 38 to 458 days (median 219). All 5 patients received other antiviral agents (e.g. ganciclovir, foscarnet), and in 4 patients, viremia was cleared before leflunomide was initiated as consolidation (or maintenance) therapy.

Conclusion

Leflunomide was well tolerated and successful in preventing recurrence of viremia in renal transplant recipients with resistant CMV infection. The beneficial effect of leflunomide in this setting warrants further investigation.

Clinical pharmacokinetics and pharmacodynamics of ganciclovir and valganciclovir in children with cytomegalovirus infection

INTRODUCTION

Among infants and immunocompromised children cytomegalovirus (CMV) is associated with significant morbidity and mortality.

AREAS COVERED

This review describes the clinical pharmacokinetics and pharmacodynamics of ganciclovir and valganciclovir for the treatment and prevention of CMV infection in children.

EXPERT OPINION

A 24-h ganciclovir area under the concentration versus time curve (AUC₀₋₂₄) of 40 - 60 μg h/ml decreased the risk of CMV infection for adults undergoing CMV prophylaxis. For adults undergoing treatment for active CMV disease, a target AUC₀₋₁₂ of 40 - 60 μg h/ml has been suggested. The applicability of these targets to children remains uncertain; however, with the most sophisticated dosing regimens developed to date only 21% of patients are predicted to reach these targets. Moving forward, identification of optimal pediatric ganciclovir and valganciclovir dosing regimens may involve the use of an externally validated pediatric population pharmacokinetic model for empirical dosing, an optimal sampling strategy for collecting a minimal number of blood samples for each patient and Bayesian updating of the dosing regimen based on an individual patient's pharmacokinetic profile.

Complete remission of VZV reactivation treated with valganciclovir in a patient with total lymphocyte depletion and acute kidney injury after allogeneic bone marrow transplantation

Varicella zoster virus (VZV), a threat for hematopoietic stem cell transplantation (HSCT) recipients, is still one of the most common viral pathogens that affect these patients with a reported incidence ranging between 17% and 50% in the post transplantation period. Valganciclovir (V-GCV), a valine ester pro-drug of GCV orally administrable, has recently shown great activity against CMV infections, but there are no reports of its clinical efficacy against VZV. We here report a case history of a patient with positive serologic test for VZV, who underwent allogeneic HSCT and developed an atypical varicella-like illness. First-line therapy with foscarnet had to be discontinued due rapid development of renal impairment (creatinine: 2.60 mg/dL, urea: 130.6 mg/dL) and therefore was switched to V-GCV. The renal impairment and skin lesions of the patient fully recovered after few days of therapy, even though the patient had complete lymphocyte depletion. This is the first case of a patient with chickenpox-like illness treated successfully with V-GCV.