Valganciclovir for the prevention and treatment of CMV in solid organ transplant recipients

Pitfalls in Valganciclovir Prophylaxis Dose Adjustment Based on Renal Function in Kidney Transplant Recipients

Valganciclovir (VGC) is administered as prophylaxis to kidney transplant recipients (KTR) CMV donor (D)+/recipient (R)- and CMV R+ after thymoglobulin-induction (R+/TG). Although VGC dose adjustments based on renal function are recommended, there is paucity of real-life data on VGC dosing and associations with clinical outcomes. This is a retrospective Swiss Transplant Cohort Study-embedded observational study, including all adult D+/R- and R+/TG KTR between 2010 and 2020, who received prophylaxis with VGC. The primary objective was to describe the proportion of inappropriately (under- or over-) dosed VGC week-entries. Secondary objectives included breakthrough clinically significant CMV infection (csCMVi) and potential associations between breakthrough-csCMVi and cytopenias with VGC dosing. Among 178 KTR, 131 (73.6%) patients had ≥2 week-entries for the longitudinal data of interest and were included in the outcome analysis, with 1,032 VGC dose week-entries. Overall, 460/1,032 (44.6%) were appropriately dosed, while 234/1,032 (22.7%) and 338/1,032 (32.8%) were under- and over-dosed, respectively. Nineteen (14.5%) patients had a breakthrough-csCMVi, without any associations identified with VCG dosing (p = 0.44). Unlike other cytopenias, a significant association between VGC overdosing and lymphopenia (OR 5.27, 95% CI 1.71-16.22, p = 0.004) was shown. VGC prophylaxis in KTR is frequently inappropriately dosed, albeit without meaningful clinical associations, neither in terms of efficacy nor safety.

Update on Viral Infections Involving the Central Nervous System in Pediatric Patients

Infections of the central nervous system (CNS) are mainly caused by viruses, and these infections can be life-threatening in pediatric patients. Although the prognosis of CNS infections is often favorable, mortality and long-term sequelae can occur. The aims of this narrative review were to describe the specific microbiological and clinical features of the most frequent pathogens and to provide an update on the diagnostic approaches and treatment strategies for viral CNS infections in children. A literature analysis showed that the most common pathogens worldwide are enteroviruses, arboviruses, parechoviruses, and herpesviruses, with variable prevalence rates in different countries. Lumbar puncture (LP) should be performed as soon as possible when CNS infection is suspected, and cerebrospinal fluid (CSF) samples should always be sent for polymerase chain reaction (PCR) analysis. Due to the lack of specific therapies, the management of viral CNS infections is mainly based on supportive care, and empiric treatment against herpes simplex virus (HSV) infection should be started as soon as possible. Some researchers have questioned the role of acyclovir as an empiric antiviral in older children due to the low incidence of HSV infection in this population and observed that HSV encephalitis may be clinically recognizable beyond neonatal age. However, the real benefit-risk ratio of selective approaches is unclear, and further studies are needed to define appropriate indications for empiric acyclovir. Research is needed to find specific therapies for emerging pathogens. Moreover, the appropriate timing of monitoring neurological development, performing neuroimaging evaluations and investigating the effectiveness of rehabilitation during follow-up should be evaluated with long-term studies.

IgA Vasculitis Complicated by Both CMV Reactivation and Tuberculosis

Immunoglobulin A (IgA) vasculitis is the most common systemic vasculitis in the pediatric population. We present the case of a patient with IgA vasculitis with nephritis who developed cytomegalovirus (CMV) infection followed by Mycobacterium tuberculosis infection. In the literature, there are a few cases of IgA nephropathy accompanied by reactivation of CMV or tuberculosis. To the best of our knowledge, this is the first reported case of IgA vasculitis complicated by both CMV reactivation and tuberculosis. It is important to detect infections in patients with IgA vasculitis because they can induce and exacerbate the symptoms of the disease. Effective antimicrobial treatment facilitates the management of proteinuria and slows down the decline of renal function. Immunosuppressive therapy is a risk factor for reactivation of latent infections and makes patients more susceptible to its generalized and complicated course. This can be prevented by actively screening for hidden sites of infection.

Role of Virus-Specific T Cell Therapy for Cytomegalovirus and BK Infections in Kidney Transplant Recipients

Cytomegalovirus (CMV) and BK virus (BKV) are common viral infections after kidney transplant. Their negative effects on patient and graft outcomes have been well described. However, despite improvement in screening and prophylaxis strategies, CMV and BKV continue to negatively affect both short- and long-term graft survival. Adequate cell-mediated immunity is essential for the control and prevention of opportunistic viral infections, such as CMV and BKV. Therefore, immune reconstitution, in particular T cell recovery, is a key factor in antiviral control after kidney transplantation. Cell-based immunotherapy offers an attractive alternative approach to traditional interventions. Adoptive T cell transfer, via infusions of allogeneic virus-specific T lymphocytes is capable of restoring virus-specific T cell immunity, and are safe and effective in the treatment of viral infections after hematopoietic stem cell transplantation. In this article, we review the emerging role of virus-specific T cell therapy in the management of CMV and BKV after kidney transplantation. On the basis of the available data, virus-specific T cell therapy may be a promising addition to the antiviral treatment armamentarium after kidney transplantation. Future studies are needed to more clearly define the efficacy and risks of virus-specific T cell therapy in the kidney transplant population.

New algorithm for valganciclovir dosing in pediatric solid organ transplant recipients

CMV infections are common after SOT. v-GCV is increasingly used in children. The aim of this study was to evaluate presently used dosing algorithms. Data from 104 pediatric SOT recipients (kidney, liver, and heart) aged 0.3-16.9 yr and receiving v-GCV once a day were used for model development and validation with the Pmetrics package for R. Monte Carlo simulations were performed to compare the probability of a GCV AUC 40-60 mg*h/L with the different algorithms across a range of ages, weights, and GFRs. GCV pharmacokinetics was well described by the non-parametric model. Clearance was dependent on GFR and Cockcroft-Gault estimates improved the model fit over Schwartz. Simulations showed that our new algorithm, where v-GCV dose is: Weight [kg]*(0.07*GFR [mL/min]+k), where k = 5 for GFR ≤ 30 mL/min, k = 10 for GFR > 30 mL/min and weight > 30 kg and k = 15 for GFR > 30 mL/min and weight ≤ 30 kg, outperformed the other algorithms. Thirty-three percent of all patients achieve an exposure above and 21% within the therapeutic window. We propose a simple algorithm for initial v-GCV dosing that standardizes plasma drug exposure better than current algorithms. Subsequent TDM is strongly suggested to achieve individual drug levels within the therapeutic window.

[Treatment of cytomegalovirus disease]

For years, intravenous ganciclovir has been the recommended treatment for cytomegalovirus (CMV) in transplant recipients. Recently, oral valganciclovir has been shown to induce a response to CMV similar to that produced by intravenous ganciclovir and could consequently be an alternative to ganciclovir in patients with non-severe disease. Sequential therapy with ganciclovir followed by valganciclovir, after the onset of clinical improvement, reduces costs and avoids prolonged hospital stays, thus benefitting patients. Optimal treatment duration is guided by clinical response and virological monitoring (polymerase chain reaction or antigenemia) and is maintained until the results are negative. Some groups use secondary prophylaxis in patients with risk factors for recurrence of CMV disease. Reducing the intensity of immunosuppression or complementing antiviral therapy with immunoglobulins can be considered in patients with severe disease or immunodepression. There are no conclusive data on the most effective treatment in ganciclovir-resistant CMV. Therapeutic decisions should be based on genotypic resistance studies, the patient's immune status and disease severity. Treatment consists of foscarnet alone or in combination with ganciclovir in the most severe forms and in high-resistance mutations, or in increasing the dose of ganciclovir in clinical forms or in mild resistance. There are no conclusive data on alternative antiviral drugs or complementary therapy with mTOR inhibitors. Several CMV vaccines are under development and the preclinical results are encouraging.

Ganciclovir pharmacokinetic parameters do not change when extending valganciclovir cytomegalovirus prophylaxis from 100 to 200 days

BACKGROUND

A 3-month course of prophylaxis is usually recommended for cytomegalovirus (CMV) D+/R- renal transplant recipients. Based on recent data, up to 6 months of prophylaxis may be used. A subanalysis was performed to evaluate the pharmacokinetics of ganciclovir after valganciclovir administration and to perform an exploratory pharmacokinetic/pharmacodynamic analysis.

METHODS

In Improved Protection Against Cytomegalovirus in Transplant, a phase III, randomized, double blind, placebo-controlled, multicenter study, 318 CMV D+/R- kidney transplant recipients received valganciclovir prophylaxis (900 mg once daily) for 200 or 100 days. A population pharmacokinetic analysis was conducted on a subgroup of patients (n=120). The relationships between ganciclovir exposure (AUC0-24 hr) and clinical outcomes were explored.

RESULTS

The final population parameter estimates (95% confidence interval) were as follows: apparent clearance of ganciclovir, 12 L/hr (11.3-12.7 L/hr); volume of distribution, 18.5 L (14.4-22.6 L); and peripheral volume, 44.4 L (40.2-48.6 L). No differences were apparent between the two treatment groups and these estimates. These results are consistent with previously published pharmacokinetic models. There were no direct correlations between the likelihood of developing hematologic adverse events and ganciclovir exposure at the time of the event. The incidence of CMV disease was not correlated with ganciclovir exposure.

CONCLUSION

The pharmacokinetics of ganciclovir were similar between the two dosing groups (100 vs. 200 days), with the majority of patients achieving an area under the concentration time curve in the target therapeutic range (40-60 μg hr/mL). The fact that the majority of patients were within the target therapeutic range and the absence of a control arm (no treatment) precluded any attempt to validate a correlation with clinical parameters (i.e., CMV disease).