Effect of duration and intensity of ganciclovir exposure on lymphoblastoid cell toxicity

Population Pharmacokinetics of Ganciclovir in Allogeneic Hematopoietic Stem Cell Transplant Patients

Treatment of cytomegalovirus (CMV) infection in allogeneic hematopoietic stem cell transplantation (alloHCT) patients with ganciclovir is complicated by toxicity and resistance. This study aimed to develop an intravenous ganciclovir population pharmacokinetic model for post-alloHCT patients and to determine dosing regimens likely to achieve suggested therapeutic exposure targets. We performed a prospective observational single-center pharmacokinetic study in adult alloHCT patients requiring treatment with intravenous ganciclovir for CMV viremia or disease. Samples were analyzed using a validated ultraperformance liquid chromatography method. Population pharmacokinetic analysis and Monte Carlo simulations (n = 1000) were performed using Pmetrics for R. Twenty patients aged 18 to 69 years were included in the study. A 2-compartment model with linear elimination from the central compartment and between occasion variability best described the data. Incorporating creatinine clearance (CLCR) estimated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and presence of continuous renal replacement therapy as covariates for ganciclovir clearance improved the model. Compared to current dosing recommendations, simulations demonstrated loading doses were required to achieve a target AUC24 of 80 to 120 mg.h/L on day 1 of induction therapy. Increased individualization of post-loading induction and maintenance doses based on CLCR is required to achieve the suggested exposures for efficacy (AUC24 >80/>40 mg.h/L for induction/maintenance) while remaining below the exposure thresholds for toxicity (AUC24 <120/<60 mg.h/L for induction/maintenance). Intravenous ganciclovir dosing in alloHCT patients can be guided by CLCR estimated by CKD-EPI. Incorporation of loading doses into induction dosing regimens should be considered for timely achievement of currently suggested exposures.

A Systematic Review of the Clinical Pharmacokinetics, Pharmacodynamics and Toxicodynamics of Ganciclovir/Valganciclovir in Allogeneic Haematopoietic Stem Cell Transplant Patients

BACKGROUND

Ganciclovir (GCV) and valganciclovir (VGCV) are the first-line agents used to prevent and treat cytomegalovirus (CMV) infection in allogeneic haematopoietic stem cell transplant (alloHCT) patients.

OBJECTIVE

The aim of this work was to describe available data for the clinical pharmacokinetics, pharmacodynamics and toxicodynamics of GCV and VGCV and the potential of a therapeutic drug monitoring strategy to improve outcomes in the alloHCT population.

METHODS

We systematically reviewed the pharmacokinetics (dose-exposure), pharmacodynamics (exposure-efficacy) and toxicodynamics (exposure-toxicity) of GCV and VGCV in alloHCT patients with CMV infection. Studies including alloHCT patients treated for CMV infection reporting the pharmacokinetics, pharmacodynamics and toxicodynamics of GCV or VGCV were searched for using the PUBMED and EMBASE databases from 1946 to 2019. Only studies involving participants > 12 years of age and available in the English language were included.

RESULTS

A total of 179 patients were included in the 14 studies that met the inclusion criteria, of which 6 examined GCV pharmacokinetics only, while 8 also examined GCV pharmacodynamics and toxicodynamics. Reported pharmacokinetic parameters showed considerable interpatient variability and were different from other populations, such as solid organ transplant and human immunodeficiency virus-infected patients. Only one study found a correlation between neutropenia and elevated peak and trough GCV concentrations, with no other significant pharmacodynamic and toxicodynamic relationships identified. While therapeutic drug monitoring of GCV is performed in some institutions, no association between GCV therapeutic drug monitoring and clinical outcomes was identified.

CONCLUSION

Further studies of the pharmacokinetics, pharmacodynamics and toxicodynamics of GCV/VGCV in alloHCT patients are required to identify a more robust therapeutic range and to subsequently quantify the potential value of therapeutic drug monitoring of GCV/VGCV in the alloHCT population.

Formulation development and in vitro evaluation of transferrin-conjugated liposomes as a carrier of ganciclovir targeting the retina

Ganciclovir (GCV) is an antiviral drug approved for treatment of cytomegalovirus (CMV) retinitis. It can be delivered to the eye via systemic administrations. However, local delivery of GCV that targets the retina is considered as an alternative to increase efficacy of the treatment and lessen side effects. Thus, this study aimed to develop formulations of transferrin (Tf)-conjugated liposomes containing GCV (Tf-GCV-LPs) for intravitreal injection and topical instillation. Tf-GCV-LPs were prepared by the reverse-phase evaporation technique and then conjugated to Tf. Their physicochemical properties were evaluated. The optimized formulation was selected and subjected to the cytotoxicity test, cellular uptake study in the human retinal pigment epithelial cells (the ARPE-19 cells) and antiviral activity evaluation. The results showed that physicochemical properties of Tf-GCV-LPs were affected by formulation compositions. The optimized Tf-GCV-LPs had a particle size lower than 100 nm with a negative value of zeta potential. They were safe for the ARPE-19 cells. These Tf-GCV-LPs were taken up by these cells via Tf receptors-mediated endocytosis and showed inhibitory activity on CMV in the infected cells. Therefore, the optimized Tf-GCV-LPs could be accepted as a promising drug delivery system for targeted GCV delivery to the retina in the treatment of CMV retinitis.

Technical approaches to induce selective cell death of pluripotent stem cells

Despite the recent promising results of clinical trials using human pluripotent stem cell (hPSC)-based cell therapies for age-related macular degeneration (AMD), the risk of teratoma formation resulting from residual undifferentiated hPSCs remains a serious and critical hurdle for broader clinical implementation. To mitigate the tumorigenic risk of hPSC-based cell therapy, a variety of approaches have been examined to ablate the undifferentiated hPSCs based on the unique molecular properties of hPSCs. In the present review, we offer a brief overview of recent attempts at selective elimination of undifferentiated hPSCs to decrease the risk of teratoma formation in hPSC-based cell therapy.

Pharmacokinetics and tissue diffusion of ganciclovir in mice and rats

BACKGROUND

Congenital cytomegalovirus (CMV) infection is the leading infectious cause of birth defects, mental retardation and non-genetic sensorineural hearing loss. Murine models have been developed in order to understand the pathophysiological mechanisms underlying these lesions. These models are being proposed for the validation of therapeutic protocols for clinical use. The aim of this preclinical study was to assess the pharmacokinetics of the reference antiviral molecule, ganciclovir, in order to optimize these protocols and confirm the diffusion of the molecule to the appropriate target zones.

METHODS

Transplacental and intracochlear diffusion of ganciclovir was evaluated in mice and rats. Pharmacokinetics was assessed in adult mice and pups after 5 consecutive days of intraperitoneal injection of ganciclovir. The occurrence of hematological side effects of ganciclovir was evaluated in the different blood cell lineages.

RESULTS

In adult rats, the intracochlear diffusion of ganciclovir was shown to achieve the same concentration as in blood. In gestating mice, transplacental diffusion was observed, with a fetal-to-maternal blood ratio of 0.5. In newborn mice, the plasma concentration profile of ganciclovir showed a peak at 2 h followed by a gradual decrease. In adult mice, the concentration peaked at 1 h, but became undetectable by 2 h after injection. Counts of white blood cells, red blood cells and platelets decreased significantly in ganciclovir-treated newborn mice.

CONCLUSION

Our data provide evidence for the intracochlear diffusion of the molecule, which may be relevant for the treatment of sensorineural hearing loss in congenitally-infected children.

Effects of four nucleoside analogues used as antiviral agents on rat Sertoli cells (SerW3) in vitro

Some nucleoside analogues are used to treat herpes simplex and other viral infections. They are known to impair spermatogenesis, but published data are scarce. We studied the effects of four nucleosides on SerW3 cells, a rat Sertoli cell line. Cells were cultured for 3 days in DMEM supplemented with four different concentrations of each drug. Aciclovir and ganciclovir were added at concentrations of 0.3, 1, 3 and 10 mg/l medium; penciclovir and its prodrug famciclovir were used at higher concentrations (3, 10, 30, 100 mg/l medium). After a culture period of 3 days, we analysed the expression of connexin43, N-cadherin and the cytoskeleton protein vimentin by Western blot. Aciclovir caused a clear-cut effect at the highest concentration tested (10 mg/l), which is less than the peak plasma concentration achieved in patients during intravenous therapy with the drug. Connexin43, vimentin and N-cadherin content decreased to 49.8 ± 17, 44.0 ± 4 and 75.4 ± 1.5 % of the control values, respectively (n = 3; mean ± SD). Similar effects were observed with the prodrug ganciclovir (43.2 ± 10.8; 54.1 ± 11.9; 84.4 ± 10.8 % of controls). Penciclovir caused less pronounced effects at 10 mg/l medium (82.1 ± 20.6; 90.0 ± 12.0; 76.5 ± 17.7 % of controls). Only a slight effect was observed with famciclovir. Even at a 10-fold concentration (100 mg/l), just moderate changes were induced. In summary, we observed clear-cut effects with aciclovir and ganciclovir on Sertoli cells in vitro at therapeutically relevant concentrations and identified connexin43 as the most sensitive marker.

Repair of Ischemic Injury by Pluripotent Stem Cell Based Cell Therapy without Teratoma through Selective Photosensitivity

Stem-toxic small molecules have been developed to induce selective cell death of pluripotent stem cells (PSCs) to lower the risk of teratoma formation. However, despite their high efficacies, chemical-based approaches may carry unexpected toxicities on specific differentiated cell types. Herein, we took advantage of KillerRed (KR) as a suicide gene, to selectively induce phototoxicity using visible light via the production of reactive oxygen species. PSCs in an undifferentiated state that exclusively expressed KR (KR-PSCs) were eliminated by a single exposure to visible light. This highly selective cell death in KR-PSCs was exploited to successfully inhibit teratoma formation. In particular, endothelial cells from KR-mPSCs remained fully functional in vitro and sufficient to repair ischemic injury in vivo regardless of light exposure, suggesting that a genetic approach in which KR is expressed in a tightly controlled manner would be a viable strategy to inhibit teratoma formation for future safe PSC-based therapies.

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Pluripotent specific KR induces ESC specific cell death by light exposure

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Specific cell death of KR-ESCs by light exposure inhibits teratoma formation

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ECs from KR-ESCs remain fully functional in vitro and in vivo by light exposure

Pharmacokinetics of ganciclovir during continuous venovenous hemodiafiltration in critically ill patients

Ganciclovir is an antiviral agent that is frequently used in critically ill patients with cytomegalovirus (CMV) infections. Continuous venovenous hemodiafiltration (CVVHDF) is a common extracorporeal renal replacement therapy in intensive care unit patients. The aim of this study was to investigate the pharmacokinetics of ganciclovir in anuric patients undergoing CVVHDF. Population pharmacokinetic analysis was performed for nine critically ill patients with proven or suspected CMV infection who were undergoing CVVHDF. All patients received a single dose of ganciclovir at 5 mg/kg of body weight intravenously. Serum and ultradiafiltrate concentrations were assessed by high-performance liquid chromatography, and these data were used for pharmacokinetic analysis. Mean peak and trough prefilter ganciclovir concentrations were 11.8 ± 3.5 mg/liter and 2.4 ± 0.7 mg/liter, respectively. The pharmacokinetic parameters elimination half-life (24.2 ± 7.6 h), volume of distribution (81.2 ± 38.3 liters), sieving coefficient (0.76 ± 0.1), total clearance (2.7 ± 1.2 liters/h), and clearance of CVVHDF (1.5 ± 0.2 liters/h) were determined. Based on population pharmacokinetic simulations with respect to a target area under the curve (AUC) of 50 mg · h/liter and a trough level of 2 mg/liter, a ganciclovir dose of 2.5 mg/kg once daily seems to be adequate for anuric critically ill patients during CVVHDF.