A study of the pharmacokinetics, antiviral activity, and tolerability of oral ganciclovir for CMV prophylaxis in marrow transplantation

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.

Population Pharmacokinetics and Dose Optimization of Ganciclovir in Critically Ill Children

Objective: The present study aims to establish a population pharmacokinetic model of ganciclovir and optimize the dosing regimen in critically ill children suffering from cytomegalovirus related disease.

Methods: A total of 104 children were included in the study. The population pharmacokinetic model was developed using the Phoenix NLME program. The final model was validated by diagnostic plots, nonparametric bootstrap, visual predictive check, and normalized prediction distribution errors. To further evaluate and optimize the dosing regimens, Monte Carlo simulations were performed. Moreover, the possible association between systemic exposure and hematological toxicity were also monitored in the assessment of adverse events.

Results: The ganciclovir pharmacokinetics could be adequately described by a one-compartment model with first-order elimination along with body weight and estimated glomerular filtration rate as significant covariates. As showed in this study, the typical population parameter estimates of apparent volume of distribution and apparent clearance were 11.35 L and 5.23 L/h, respectively. Simulations indicated that the current regimen at a dosage of 10 mg/kg/d would result in subtherapeutic exposure, and elevated doses might be required to reach the target ganciclovir level. No significant association between neutropenia, the most frequent toxicity reported in our study (19.23%), and ganciclovir exposure was observed.

Conclusion: A population pharmacokinetic model of intravenous ganciclovir for critically ill children with cytomegalovirus infection was successfully developed. Results showed that underdosing of ganciclovir was relatively common in critically ill pediatric patients, and model-based approaches should be applied in the optimizing of empiric dosing regimens.

Cytotect®CP as salvage therapy in patients with CMV infection following allogeneic hematopoietic cell transplantation: a multicenter retrospective study

Cytomegalovirus is one of the main contributing factors to high mortality rates in patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT). The main factors of treatment failure are both drug resistance and intolerance. In some cases, Cytotect®CP CMV-hyperimmune globulin is used as salvage therapy. This study aims to investigate the safety and efficacy of Cytotect®CP as a salvage therapy in patients with CMV infection after allo-HCT. Twenty-three consecutive patients received Cytotect®CP for CMV infection after prior CMV therapy. At the time of Cytotect®CP introduction, 17 patients (74%) had developed acute GVHD and 15 patients (64%) were receiving steroid treatment; Cytotect®CP was used as monotherapy (n = 7) and in combination (n = 16). Overall, response was observed in 18 patients (78%) with a median time of 15 days (range: 3-51). Of the 18 responders, 4 experienced CMV reactivation, while 5 responders died within 100 days of beginning treatment. Of these 5 deaths, 4 were due to causes unrelated to CMV. Estimated 100-day OS from the introduction of Cytotect®CP was 69.6%. No statistically significant difference was observed in 100-day OS between responders and non-responders (73.7% vs 50.0%, p = 0.258). Cytotect®CP as salvage therapy is effective and well-tolerated. Given its safety profile, early treatment use should be considered.

Prophylactic and therapeutic adenoviral vector-based multivirus-specific T-cell immunotherapy for transplant patients

Viral infections including cytomegalovirus, Epstein-Barr virus, adenovirus, and BK virus are a common and predictable problem in transplant recipients. While cellular immune therapies have been successfully used to tackle infectious complications in transplant recipients, manufacturing immunotherapies to address the multitude of possible pathogens can be technically challenging and labor-intensive. Here we describe a novel adenoviral antigen presentation platform (Ad-MvP) as a tool for rapid generation of multivirus-specific T-cells in a single step. Ad-MvP encodes 32 CD8+ T-cell epitopes from cytomegalovirus, Epstein-Barr virus, adenovirus, and BK virus as a contiguous polyepitope. We demonstrate that Ad-MvP vector can be successfully used for rapid in vitro expansion of multivirus-specific T-cells from transplant recipients and in vivo priming of antiviral T-cell immunity. Most importantly, using an in vivo murine model of Epstein-Barr virus-induced lymphoma, we also show that adoptive immunotherapy with Ad-MvP expanded autologous and allogeneic multivirus-specific T-cells is highly effective in controlling Epstein-Barr virus tumor outgrowth and improving overall survival. We propose that Ad-MvP has wide ranging therapeutic applications in greatly facilitating in vivo priming of antiviral T-cells, the generation of third-party T-cell banks as “off-the-shelf” therapeutics as well as autologous T-cell therapies for transplant patients.

Risk factors for ganciclovir-induced thrombocytopenia and leukopenia

Ganciclovir is a nucleoside guanosine analogue that exhibits therapeutic activity against human cytomegalovirus infection, and is primarily excreted via glomerular filtration and active tubular secretion. The adverse effects induced by ganciclovir therapy are generally of a hematological nature and include thrombocytopenia and leukopenia. Low marrow cellularity and elevated serum creatinine have been identified as risk factors for ganciclovir-induced neutropenia. However, the risk factors for thrombocytopenia have yet to be determined. Therefore, this study investigated patients administered ganciclovir to determine the risk factors for thrombocytopenia and leukopenia. Thrombocytopenia occurred in 41 of these patients (30.6%). Multivariate logistic regression analysis identified three independent risk factors for thrombocytopenia: cancer chemotherapy (odds ratio (OR)=3.1), creatinine clearance (<20 mL/min) (OR=12.8), and the ganciclovir dose (≥12 mg/kg/d) (OR=15.1). Leukopenia occurred in 36 patients (28.6%), and white blood cell count (<6000 cells/mm(3)) (OR=3.7) and the ganciclovir dose (≥12 mg/kg/d) (OR=7.8) were identified as risk factors. These results demonstrated that several factors influenced the occurrence of ganciclovir-induced thrombocytopenia and leukopenia, and suggest that special attention should be paid to patients receiving cancer chemotherapy with a low creatinine clearance (<20 mL/min) and high dose (≥12 mg/kg/d) in order to avoid ganciclovir-induced thrombocytopenia.

Valganciclovir as pre-emptive therapy for cytomegalovirus infection in allogeneic haematopoietic stem cell transplant recipients

BACKGROUND

In haematopoietic stem cell transplant (HSCT) recipients, cytomegalovirus (CMV) infection contributes significantly to morbidity and mortality in both the early and late post-transplant period. Ganciclovir (GCV) is the treatment of choice for CMV, but requires intravenous administration, a fact that complicates its long-term use. Oral valganciclovir (VGCV) and intravenous GCV were recently shown to have similar efficacy for pre-emptive CMV treatment in solid organ transplant recipients, but relatively limited data are available in HSCT recipients. The objectives of this study were to compare the efficacy of VGCV versus intravenous GCV or foscarnet (FOS) for pre-emptive therapy of active CMV infection in allogeneic HSCT and to determine the incidence of adverse effects and relapses.

METHODS

This was a 2-year prospective, comparative cohort study in which 237 episodes of pre-emptive therapy for active CMV infection were collected in 166 allogeneic HSCT recipients out of 717 included in the Spanish Network for Research on Infection in Transplantation (RESITRA/REIPI) database. Intravenous GCV was the first-line treatment in 112 episodes, intravenous FOS in 38 episodes, and oral VGCV in 87 episodes.

RESULTS

VGCV was used as pre-emptive therapy for active CMV infection in 87 episodes. Excluding episodes considered as relapse, VGCV was as successful (91.4% [74/81]) as GCV (83.7% [87/14]) or FOS (75.8% [25/33]). In the VGCV arm, 7 (8.6%) cases were considered treatment failures: 4 (4.9%) because of adverse events, 1 (1.2%) due to persistent viral activity and 2 (2.5%) based on clinical decision. There were also 6 (7.4%) cases of recurrent infection. No statistically significant differences were found when compared to GCV or FOS.

CONCLUSIONS

In allogeneic HSCT recipients, VGCV seemed effective and safe in the pre-emptive therapy of active CMV infection.

Maribavir prophylaxis for prevention of cytomegalovirus infection in allogeneic stem cell transplant recipients: a multicenter, randomized, double-blind, placebo-controlled, dose-ranging study

The anti-cytomegalovirus (CMV) activity and safety of oral maribavir in CMV-seropositive allogeneic stem-cell transplant recipients were evaluated in a randomized, double-blind, placebo-controlled, dose-ranging study. After engraftment, 111 patients were randomized to receive CMV prophylaxis with maribavir (100 mg twice daily, 400 mg once daily, or 400 mg twice daily) or placebo. Within the first 100 days after transplantation, the incidence of CMV infection based on CMV pp65 antigenemia was lower in each of the respective maribavir groups (15%, P = .046; 19%, P = .116; 15%, P = .053) compared with placebo (39%). Similarly, the incidence of CMV infection based on plasma CMV DNA was lower in each of the respective maribavir groups (7%, P = .001; 11%, P = .007; 19%, P = .038) compared with placebo (46%). Anti-CMV therapy was also used less often in patients receiving each respective dose of maribavir (15%, P = .001; 30%, P = .051; 15%, P = .002) compared with placebo (57%). There were 3 cases of CMV disease in placebo patients but none in the maribavir patients. Adverse events, mostly taste disturbance, nausea, and vomiting, were more frequent with maribavir. Maribavir had no adverse effect on neutrophil or platelet counts. These results show that maribavir can reduce the incidence of CMV infection and, unlike ganciclovir, does not cause myelosuppression.

Cancer-specific targeting of an adenovirus-delivered herpes simplex virus thymidine kinase suicide gene using translational control

Two technical hurdles, gene delivery and target specificity, have hindered the development of effective cancer gene therapies. In order to circumvent the problem of tumor specificity, the suicide gene, HSV-1 thymidine kinase (HSV-Tk), was modified with a complex 5' upstream-untranslated region (5'-UTR) that limits efficient translation to cells expressing high levels of the translation initiation factor, eIF4E. Since previous studies have shown that most tumor cells express elevated levels of eIF4E, tumor-specific gene delivery was optimized by incorporation of the 5'-UTR-modified suicide gene (HSV-UTk) into an adenovirus vector (Ad-CMV-UTk). The efficacy of this novel approach of targeting suicide gene expression and limiting cytotoxicity by means of translational restriction was tested in vitro with the use of the human breast cancer cell lines (MCF-7, MDA-MB435, and ZR-75-1). As controls, normal MCF10A, HMEC, and HMSC cell lines that express relatively low levels of eIF4E were used. Real-time reverse-transcription polymerase chain reaction (RT-PCR) was used to quantify HSV-Tk mRNA for cells infected with Ad-CMV-UTk as well as with Ad-CMV-Tk (a control adenovirus in which HSV-Tk is not regulated at the level of translation). Translation of HSV-Tk in the Ad-infected cells was measured by Western blot analysis. In addition, cytotoxicity was determined following treatment with the pro-drug ganciclovir (GCV) using an MTT viability assay. Finally, microPET imaging was used to assess cancer cell-specific expression of HSV-Tk and expression in normal tissues in vivo after intraperitoneal injection of Ad-CMV-Tk or Ad-CMV-UTk. These data collectively showed enhanced cancer cell-specific gene expression and reduced normal tissue gene expression for the Ad-HSV-UTk compared to the Ad-CMV-Tk, leading to increased cancer cell-enhanced GCV cytotoxicity. These results indicate that translational targeting of suicide gene expression in tumor cells in vitro and in vivo is effective and may provide a platform for enhanced cancer gene therapy specificity.

Pharmacokinetics of ganciclovir after oral valganciclovir versus intravenous ganciclovir in allogeneic stem cell transplant patients with graft-versus-host disease of the gastrointestinal tract

The pharmacokinetics of ganciclovir after oral valganciclovir versus intravenous ganciclovir were compared in allogeneic stem cell transplant recipients with stable graft-versus-host disease of the gastrointestinal tract. Twenty-two evaluable adult patients were randomized to receive a single dose of open-label study drug (900 mg of oral valganciclovir or 5 mg/kg of intravenous ganciclovir). After a washout period of 2 to 7 days, patients were crossed over to receive the alternate study drug. Ganciclovir and valganciclovir concentrations in plasma were measured over 24 hours after dosing. Noninferiority of 900 mg of valganciclovir relative to intravenous ganciclovir was concluded if the lower limit of the 1-sided 95% confidence interval of the ratio of least-square means of the ganciclovir area under the curve (AUC) for the 2 study drugs was >80%. Valganciclovir was found to be rapidly absorbed and converted into ganciclovir. The ganciclovir exposure after 900 mg of valganciclovir noninferior to that of intravenous ganciclovir (AUC0-infinity, 52.1 and 53.8 microg.h/mL, respectively; 95% confidence interval of the ratio of least square means of AUC0-infinity, 82.48%-118.02%). Oral valganciclovir could be a useful alternative to intravenous ganciclovir in certain stable stem cell transplant patients who require prophylaxis or preemptive therapy for cytomegalovirus infection.

Human cytomegalovirus: clinical aspects, immune regulation, and emerging treatments

After initial infection, human cytomegalovirus remains in a persistent state with the host. Immunity against the virus controls replication, although intermitent viral shedding can still take place in the seropositive immunocompetent person. Replication of cytomegalovirus in the absence of an effective immune response is central to the pathogenesis of disease. Therefore, complications are primarily seen in individuals whose immune system is immature, or is suppressed by drug treatment or coinfection with other pathogens. Although our increasing knowledge of the host-virus relationship has lead to the development of new pharmacological strategies for cytomegalovirus-associated infections, these strategies all have limitations-eg, drug toxicities, development of resistance, poor oral bioavailability, and low potency. Immune-based therapies to complement pharmacological strategies for the successful treatment of virus-associated complications should be prospectively investigated.

Risk factors for post-engraftment invasive aspergillosis in allogeneic stem cell transplantation

The majority of invasive aspergillosis (IA) in allogeneic stem cell transplantation (SCT) occurs during the post-engraftment period. We used Cox proportional hazards regression to evaluate post-engraftment IA risk in a cohort of 217 allogeneic SCT recipients from 1991 to 1998. The aim was to quantify the effects of dose-intensity and duration of corticosteroids and other risk factors. Median duration of follow-up was 330 days. There were 19 cases of IA (overall 8.8%) with 14 post-engraftment infections. In the final model, the risk of IA was greatest within 2 weeks of high-dose corticosteroids (HR 8.5, P=0.003), with risk extending to 4 weeks with doses of 0.25-1 mg/kg/day (HR 3.1, P=0.08). Ganciclovir was associated with greatest risk (HR 13.6). Grade 3 or 4 acute GVHD (HR 5.7) and secondary neutropenia (HR=1.3) were also additive risks. In the univariate analysis, corticosteroid doses of 0.25-1.0 mg/kg/day for any duration between 2 and 10 weeks demonstrated prolonged risk for IA. Moderate doses of corticosteroids can confer an increased risk for IA for extended periods which is almost as marked as that conferred by higher doses. Knowledge of these risks may facilitate the development of targeted surveillance and prophylaxis strategies for prevention of IA.

Oral versus intravenous ganciclovir for the prophylaxis of cytomegalovirus disease after allogeneic bone marrow transplantation

BACKGROUND

Prophylactic low dose i.v. ganciclovir in patients at risk after allogeneic bone marrow transplantation (BMT) is highly effective in the prevention of cytomegalovirus (CMV) disease and infection.

AIM

In this study, we sought to assess the tolerability of oral ganciclovir in patients after allogeneic BMT.

METHODS

CMV seropositive patients or those with CMV seropositive donors were randomised to be treated with i.v. ganciclovir 5 mg/kg three times weekly or oral ganciclovir 3 g daily from engraftment to day 84. The period of accrual was from May 1997 to October 1998. Patients were monitored for CMV infection by weekly serology. Thirty-one patients received oral ganciclovir and 27 patients received i.v. ganciclovir, the treatment groups being balanced for clinical characteristics and prognostic factors.

RESULTS

Renal dysfunction, transfusion requirements and significant nausea and vomiting were not different. There were no documented cases of CMV disease during the study period although three patients developed CMV polymerase chain reaction positivity at various times. One patient treated with i.v. ganciclovir developed non-fatal gastrointestinal CMV disease after the study period on day 108. Eight patients in the oral group failed to complete planned therapy, whereas two patients failed to complete the i.v. course.

CONCLUSION

We conclude that oral ganciclovir is a reasonable, well-tolerated alternative to i.v. ganciclovir for the prophylaxis of CMV disease after allogeneic BMT.

Oncolytic herpes viruses as a potential mechanism for cancer therapy

Oncolytic viruses have been considered as a potential form of cancer treatment throughout the last century because of their ability to lyse and destroy tumor cells both in tissue culture and in animal models of cancer. However, it is only during the past decade that new molecular technologies have become available and understanding of genetic and molecular components of these viruses has increased to the point that they can be manipulated and made safe for use in treatment in humans. Thus there has been a revival of the concepts of conditionally replication-competent viruses and suicide gene therapy to supplement currently existing cancer therapies. While a wide variety of viruses have been closely studied for this purpose, herpes simplex virus type-1 (HSV-1) has received particularly close attention. The inherent cytotoxicity of this virus, if harnessed and made to be selective in the context of a tumor microenvironment, makes this an ideal candidate for further development. Furthermore, its large genome size, ability to infect cells with a high degree of efficiency, and the presence of an inherent viral-specific thymidine kinase gene add to its potential capabilities. This review explores work performed in this field and its potential for application in the treatment of cancers in humans.

Cytomegalovirus in hematopoietic stem cell transplant recipients: current status, known challenges, and future strategies

Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality after hematopoietic stem cell transplantation. Significant progress has been made in the prevention of CMV disease over the past decade, but prevention of late CMV disease continues to be a challenge in selected high-risk populations. The pretransplantation CMV serostatus of the donor and/or recipient remains an important risk factor for posttransplantation outcome despite the use of antiviral prophylaxis and preemptive therapy; CMV-seropositive recipients of T cell-depleted grafts in particular continue to have a survival disadvantage compared with seronegative recipients with seronegative donors. The risk of developing antiviral drug resistance remains low in most patients; however, in a setting of intense immunosuppression (eg, after transplantation from a haploidentical donor), the incidence may be as high as 8%. Primary CMV infection via blood transfusion can be reduced by the provision of seronegative or leukocyte-depleted blood products; however, a small risk of 1% to 2% of CMV disease remains. Surveillance and preemptive therapy are effective in preventing the sequelae of transfusion-related CMV infection. Indirect immunomodulatory effects of CMV are increasingly recognized in hematopoietic stem cell transplant recipients. Strategies currently being investigated include long-term suppression of CMV with valganciclovir for the prevention of late CMV infection and disease, adoptive transfer of CMV-specific T cells, and donor and recipient vaccination strategies.

Prevention of cytomegalovirus disease in hematopoietic stem cell transplantation

Prevention of cytomegalovirus (CMV) infection after hematopoietic stem cell transplantation (HSCT) generally involves preemptive treatment of recognized infection before the onset of overt CMV-associated disease. The success of this method depends on efficient recognition of infection and intervention before the disease progresses. Reliable tests for such diagnosis include blood culture, antigenemia assays, polymerase chain reaction assays, and other DNA sequence- or RNA sequence-based assays. For selected high-risk patients, such as patients receiving T cell-depleted hematopoietic stem cell transplants, prophylactic use of antiviral agents before the onset of CMV infection is recommended. The ability to monitor the immunological status of the patient relative to CMV-specific immunity is increasing in importance. Ultimately, the solution to the problem of efficient prevention of CMV infection in this population will require combined antiviral chemotherapy and improved reconstitution of CMV immunity.

CNS manifestations of cytomegalovirus infections: diagnosis and treatment

Cytomegalovirus (CMV) infection of the CNS occurs most commonly in patients with severe immunosuppression such as those with advanced HIV infection (i.e. AIDS) or those who have undergone bone marrow or solid organ transplantation. Immunocompetent patients are affected very rarely. The infection of the CNS may affect the brain (diffuse encephalitis, ventriculoencephalitis, cerebral mass lesions) or the spinal cord (transverse myelitis, polyradiculomyelitis). Diagnosis is very difficult and should be based on clinical presentation, results of imaging and virological markers. The most specific diagnostic tool is the detection of CMV DNA by polymerase chain reaction in the CSF. Treatment should be initiated promptly if CMV infection is suspected. Antiviral therapy consists of intravenous ganciclovir, intravenous foscarnet or a combination of both. Cidofovir is the treatment of second choice. Patients who experience clinical improvement or stabilisation during induction therapy should be given maintenance therapy. After immune reconstitution (in HIV-positive patients) or discontinuation of immunosuppressive therapy (in transplant recipients), maintenance therapy may be stopped. Despite therapy, the prognosis for long-term survival is very poor, especially in patients with AIDS.

Prevention and management of CMV-related problems after hematopoietic stem cell transplantation

Prevention and management of human cytomegalovirus (CMV) infection after hematopoietic stem cell transplantation has improved substantially in the past decade. However, with this improvement, there is increased complexity in deciding which diagnostic tests, treatment strategies and immunologic assessments are optimal for different patient populations. The purpose of this review is to address certain practical problems that commonly arise and suggest a suitable approach to management that should have wide applicability.

Ganciclovir: an update of its use in the prevention of cytomegalovirus infection and disease in transplant recipients

Ganciclovir is a nucleoside guanosine analogue which incorporates ganciclovir triphosphate (the active moiety) into DNA during elongation, thereby inhibiting viral replication. Comparative studies of pre-emptive and prophylactic ganciclovir therapies in bone marrow transplant (BMT) recipients have shown similar rates of cytomegalovirus (CMV) infection, disease and patient mortality. Long term prophylaxis with either oral, or sequential intravenous/oral, ganciclovir has shown efficacy in renal allograft recipients, including high risk patients or those receiving antilymphocyte antibody therapy. A preliminary study indicates that ganciclovir is more efficacious than aciclovir in paediatric patients. Both oral and intravenous prophylactic ganciclovir regimens have shown efficacy compared with no antiviral treatment in lung transplant recipients; initial reports have shown similar efficacy between pre-emptive and prophylactic ganciclovir. Oral ganciclovir monotherapy is as efficacious as sequential intravenous/oral ganciclovir therapy in liver transplant recipients. Pre-emptive treatment was equally as effective as long term ganciclovir prophylaxis in high risk patients. Ganciclovir prophylaxis for 4 weeks appears ineffective in heart allograft recipients treated with antithymocyte globulin. Long term sequential intravenous/ oral ganciclovir therapy has shown greater efficacy in preventing CMV disease than sequential ganciclovir/aciclovir therapy. in these patients. Initial reports indicate that pre-emptive therapy may be beneficial in this patient group. although this remains to be determined. Ganciclovir in therapeutic dosage regimens generally has acceptable tolerability with adverse effects usually of a haematological or neurological nature. Neutropenia, thrombocytopenia and anaemia are the primary dose-limiting toxicities associated with ganciclovir therapy. Overall, neutropenia occurs less frequently with administration of oral ganciclovir than with intravenous ganciclovir. Monitoring of renal function is recommended as serum creatinine levels may rise during ganciclovir therapy. In addition, ganciclovir prophylaxis appears more cost effective than the majority of other currently available therapies for CMV with oral ganciclovir more cost effective than intravenous ganciclovir. In conclusion, it is unlikely that a single strategy will be able to be applied to all transplant patients for the prevention of CMV disease. An optimal strategy will probably be arisk-adapted approach. Prophylactic treatment with ganciclovir appears the best strategy to implement in high risk patients: oral ganciclovir formulations may be best employed where lower toxicity is required. Pre-emptive treatment with ganciclovir appears most efficacious in patients identified as lower risk or, in the case of BMT recipients, where lower toxicity may be desirable. Ganciclovir remains an important therapeutic option for the prevention and treatment of CMV disease in transplant recipients.

Increased oral ganciclovir bioavailability in HIV-infected patients with chronic diarrhoea and wasting syndrome--a population pharmacokinetic study

AIMS

Despite a lack of data, the antiviral agent ganciclovir is not indicated in AIDS patients with diarrhoea because of its presumed poor oral bioavailability. To assess the effect of diarrhoea on ganciclovir intestinal absorption, we conducted a pharmacokinetic study in 42 HIV-infected patients categorized into three groups: A, HIV stage A and B (n = 15); B, AIDS stage C (n = 13); C, AIDS with chronic diarrhoea and wasting syndrome (n = 14).

METHODS

Each patient was evaluated for nutritional (body mass index, albumin, transferrin serum levels), inflammatory (haptoglobin, orosomucoid), immunological (CD4 count, plasma viral load) and intestinal (D-xylose test, faecal fat and nitrogen output, intestinal permeability) status. Ganciclovir (1 g) was administered orally to fasted patients. Six blood samples were collected over 24 h. Serum was analysed for ganciclovir by h.p.l.c. Population pharmacokinetic analysis was performed using a nonlinear mixed effects modelling program, MP2.

RESULTS

Mean intestinal permeability (lactulose/mannitol urinary ratio) was increased in group C (0.2) compared with group A (0.05) and B (0.1) patients. Drug concentration-time profiles were best described by a two-compartment model. Apparent oral clearance (CL/F) and central volume of distribution (V1/F) were influenced by clinical status (group). For groups A and B combined, final parameter estimates of CL/F and V1/F were 256 +/- 98 l h(-1) and 1320 +/- 470 l, respectively. Final parameter estimates for group C were 118 +/- 108 l h(-1) and 652 +/- 573 l for CL/F and V1/F, respectively. The 95% confidence intervals on differences between A and B combined and C were statistically significant ([ + 70, + 206] for CL/F, and [+ 314, + 1022] for V1/F). Compared with groups A and B, ganciclovir CL/F was significantly decreased in group C patients.

CONCLUSIONS

AIDS patients with diarrhoea and severe disease may benefit from ganciclovir therapy, but a dose adjustment may be required according to their digestive and immunological status.

Prophylaxis against herpesvirus infections in transplant recipients

Herpesvirus infections are important after stem cell and organ transplant. During the last decades several antiviral agents have been introduced with efficacy against herpesviruses. These agents are the nucleoside analogues aciclovir, valaciclovir, famciclovir, and ganciclovir; the nucleotide analogue cidofovir; and the pyrophosphate analogue foscarnet. Several studies have been performed with antiviral agents with the aim to reduce morbidity and mortality associated with herpesvirus infections in transplant recipients. Aciclovir and valaciclovir have been examined in randomised, controlled trials in both solid organ and stem cell transplant patients, and were shown to be very effective for the prevention of herpes simplex virus (HSV) and varicella-zoster virus infections. In addition, these drugs were shown to reduce cytomegalovirus (CMV) infection and improve survival in allogenic stem cell transplant patients and to reduce CMV infection, CMV disease (aciclovir and valaciclovir), and acute rejection (valaciclovir) in renal transplant patients. Ganciclovir is very effective for the prevention of CMV infection and disease in both stem cell and solid organ transplant recipients. It can also be used in preemptive strategies in which the aim is to prevent CMV disease in patients who have ongoing CMV infection documented by antigenaemia or detection of CMV DNA. The latter strategy has the advantage of reducing the exposure to the drug and thereby the risk for toxicity. Foscarnet has also been shown to be effective as preemptive therapy for CMV in allogenic stem cell transplant patients and as therapy for aciclovir-resistant HSV infections. Finally cidofovir is an interesting agent with broad spectrum antiherpesvirus efficacy. However, because of the drug's toxicity profile, further studies are needed.

Preventing opportunistic infections after hematopoietic stem cell transplantation: the Centers for Disease Control and Prevention, Infectious Diseases Society of America, and American Society for Blood and Marrow Transplantation Practice Guidelines and beyond

This review presents evidence-based guidelines for the prevention of infection after blood and marrow transplantation. Recommendations apply to all myeloablative transplants regardless of recipient (adult or child), type (allogeneic or autologous) or source (peripheral blood, marrow or cord blood) of transplant. In Section I, Dr. Dykewicz describes the methods used to rate the strength and quality of published evidence supporting these recommendations and details the two dozen scholarly societies and federal agencies involved in the genesis and review of the guidelines. In Section II, Dr. Longworth presents recommendations for hospital infection control. Hand hygiene, room ventilation, health care worker and visitor policies are detailed along with guidelines for control of specific nosocomial and community-acquired pathogens. In Section III, Dr. Boeckh details effective practices to prevent viral diseases. Leukocyte-depleted blood is recommended for cytomegalovirus (CMV) seronegative allografts, while ganciclovir given as prophylaxis or preemptive therapy based on pp65 antigenemia or DNA assays is advised for individuals at risk for CMV. Guidelines for preventing varicella-zoster virus (VZV), herpes simplex virus (HSV) and community respiratory virus infections are also presented. In Section IV, Drs. Baden and Rubin review means to prevent invasive fungal infections. Hospital design and policy can reduce exposure to air contaminated with fungal spores and fluconazole prophylaxis at 400 mg/day reduces invasive yeast infection. In Section V, Dr. Sepkowitz details effective clinical practices to reduce or prevent bacterial or protozoal disease after transplantation. In Section VI, Dr. Sullivan reviews vaccine-preventable infections and guidelines for active and passive immunizations for stem cell transplant recipients, family members and health care workers.

Recent advances in the therapy and prevention of CMV infections

The introduction of highly active antiretroviral therapy (HAART) for HIV has had a major impact on the treatment of CMV disease in HIV-infected individuals. There is mounting evidence that in patients with CMV retinitis who have a sustained response to HAART, CMV maintenance treatment can be discontinued without relapse of retinitis. In HAART-naïve individuals with newly diagnosed CMV retinitis, the optimal timing for the initiation of HAART relative to the start of anti-CMV treatment is currently unknown. New local therapies for CMV retinitis (e.g. ganciclovir implant, the new antisense compound fomivirsen) provide treatment options in situations where high local drug delivery is warranted. A treatment algorithm for CMV disease in the HAART era is proposed. In the transplant setting, ganciclovir and foscarnet remain the major compounds used for treatment of CMV disease. In marrow and stem cell transplant recipients, CMV pneumonia still carries a high mortality. Ganciclovir in combination with CMV-specific immunoglobulin or regular intravenous IG remains the treatment of choice for CMV pneumonia; extended antiviral maintenance for several months is recommended in patients with continued immunosuppression. Preemptive treatment based on virologic markers (e.g. pp65 antigenemia, CMV DNA) has been very successful in reducing the incidence of early CMV disease in the transplant setting. The duration of preemptive treatment should be guided by the underlying immunosuppression and virologic markers. Late CMV disease is a challenge in marrow and stem cell transplant recipients, and occurs increasingly in highly immunosuppressed solid organ transplant recipients as well. Recent advances in prophylaxis strategies include oral ganciclovir for liver transplant recipients and valacyclovir for kidney transplant recipients.

Current antiviral strategies for controlling cytomegalovirus in hematopoietic stem cell transplant recipients: prevention and therapy

Cytomegalovirus (CMV) remains a cause of significant morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Ganciclovir prophylaxis, or preemptive treatment based on detection of antigenemia or CMV DNA by PCR, effectively prevents CMV disease during the first 100 days after transplant in allograft recipients. In recipients of T-cell depleted transplant or if severe acute graft-versus-host disease is present, ganciclovir prophylaxis or preemptive treatment should be started with an induction course of ganciclovir (5 mg/kg BID) and given at least 5 days per week and continued until day 100 after transplant. Although prevention of CMV disease before day 100 is highly effective, there is a continued risk of late-onset CMV disease after day 100. In CMV-seropositive recipients, the incidence of late CMV disease may be as high as 17%. Strategies to prevent late CMV infection and disease are needed. In seronegative recipients, seronegative or leukocyte-reduced blood products are effective in preventing acquisition of CMV through blood products. Controversy exists about the optimal strategy of preventing CMV disease in seropositive autologous HSCT recipients. The outcome of CMV pneumonia remains poor despite treatment with ganciclovir in combination with CMV hyperimmune globulin or intravenous immunoglobulin. Owing to continued clinical significance of CMV in the HSCT setting, new and more effective anti-CMV drugs with improved pharmacokinetic properties are urgently needed.