Cytomegalovirus disease after heart transplantation: is acyclovir prophylaxis indicated?

WITHDRAWN: Cytomegalovirus prophylaxis with antiviral agents for solid organ transplantation

BACKGROUND

Cytomegalovirus (CMV) disease is a major cause of morbidity and mortality in solid organ transplantation. It is also associated with an increased risk of opportunistic infections, allograft injury and higher transplantation costs. CMV infection also seems to increase the risk of acute and chronic rejection of allografts via immune-mediated vascular injury. These serious consequences of CMV disease have lead to the development of effective strategies for the prevention, early diagnosis and treatment. However, there is no consensus on the necessity and the efficacy of CMV prophylaxis.

OBJECTIVES

To assess the efficacy of antiviral agents in solid organ transplant recipients in the prevention of cytomegalovirus infection and symptomatic disease and in the reduction of the incidence of acute rejection, graft loss and death.

SEARCH STRATEGY

A computerised search was conducted on Medline, Embase and Pascal. The reference lists of the current review articles and some congress proceedings were searched manually (Transplantation Proceedings, American Thoracic Society, European Society of Organ Transplantation).

SELECTION CRITERIA

Prospective, randomised studies in adults or paediatric recipients of a solid organ transplant, in which one arm received a prophylactic treatment with acyclovir and/or ganciclovir, started before cytomegalovirus infection, and the control arm received placebo or no treatment.

DATA COLLECTION AND ANALYSIS

Data were extracted from each trial and a letter sent to the authors to ask them to verify the data extracted, and to provide any data that was missing. For each outcome, several methods were used to calculate the chi-square for association and the estimate for the treatment effect with its 95% CI, with an additive model (rate difference), or a multiplicative model (odds ratio, relative risk). We considered the test of association to be significant when the p value was less than 0.01 and the homogeneity test to be significant when the p value was less than 0.1.

MAIN RESULTS

Prophylactic treatment was found to be associated with a significant decrease in cytomegalovirus disease compared with placebo or no treatment, using the logarithm of relative risk method (RR 0.51, 95% CI 0.41-0.64, p value for X(2) association < 0.001). Prophylactic treatment also decreased the rate of cytomegalovirus infection (RR 0.62, 95%CI 0.53-0.73, p < 0.001). Our analysis failed to show a significant decrease in graft loss, acute rejection or death in the prophylactic treatment group. Sub-group analysis based on the type of antiviral agent (acyclovir or ganciclovir) and on the type of organ (kidney or liver) gave comparable results.

AUTHORS' CONCLUSIONS

The use of antiviral agents for the prevention of cytomegalovirus disease and cytomegalovirus infection in solid organ transplantation is supported by this meta-analysis.

Current and potential therapies for the treatment of herpes-virus infections

Human herpesviruses are found worldwide and are among the most frequent causes of viral infections in immunocompetent as well as in immunocompromised patients. During the past decade and a half a better understanding of the replication and disease-causing state of herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella zoster virus (VZV), and human cytomegalovirus (HCMV) has been achieved due in part to the development of potent antiviral compounds that target these viruses. While some of these antiviral therapies are considered safe and efficacious (acyclovir, penciclovir), some have toxicities associated with them (ganciclovir and foscarnet). In addition, the increased and prolonged use of these compounds in the clinical setting, especially for the treatment of immunocompromised patients, has led to the emergence of viral resistance against most of these drugs. While resistance is not a serious issue for immunocompetent individuals, it is a real concern for immunocompromised patients, especially those with AIDS and the ones that have undergone organ transplantation. All the currently approved treatments target the viral DNA polymerase. It is clear that new drugs that are more efficacious than the present ones, are not toxic, and target a different viral function would be of great use especially for immunocompromised patients. Here, an overview is provided of the diseases caused by the herpesviruses as well as the replication strategy of the better studied members of this family for which treatments are available. We also discuss the various drugs that have been approved for the treatment of some herpesviruses in terms of structure, mechanism of action, and development of resistance. Finally, we present a discussion of viral targets other than the DNA polymerase, for which new antiviral compounds are being considered.

Current and potential therapies for the treatment of herpesvirus infections

Human herpesviruses are found worldwide and are among the most frequent causes of viral infections in immunocompetent as well as in immunocompromised patients. During the past decade and a half a better understanding of the replication and disease causing state of herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), and human cytomegalovirus (HCMV) has been achieved due in part to the development of potent antiviral compounds that target these viruses. While some of these antiviral therapies are considered safe and efficacious (acyclovir, penciclovir), some have toxicities associated with them (ganciclovir and foscarnet). In addition, the increased and prolonged use of these compounds in the clinical setting, especially for the treatment of immunocompromised patients, has led to the emergence of viral resistance against most of these drugs. While resistance is not a serious issue for immunocompetent individuals, it is a real concern for immunocompromised patients, especially those with AIDS and the ones that have undergone organ transplantation. All the currently approved treatments target the viral DNA polymerase. It is clear that new drugs that are more efficacious than the present ones, are not toxic, and target a different viral function would be of great use especially for immunocompromised patients. Here, we provide an overview of the diseases caused by the herpesviruses as well as the replication strategy of the better studiedmembers of this family for which treatments are available. We also discuss the various drugs that have been approved for the treatment of some herpesviruses in terms of structure, mechanism of action, and development of resistance. Finally, we present a discussion of viral targets other than the DNA polymerase, for which new antiviral compounds are being considered.

Current and potential therapies for the treatment of herpesvirus infections

Human herpesviruses are found worldwide and are among the most frequent causes of viral infections in immunocompetent as well as in immunocompromised patients. During the past decade and a half a better understanding of the replication and disease causing state of herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), and human cytomegalovirus (HCMV) has been achieved due in part to the development of potent antiviral compounds that target these viruses. While some of these antiviral therapies are considered safe and efficacious (acyclovir, penciclovir), some have toxicities associated with them (ganciclovir and foscarnet). In addition, the increased and prolonged use of these compounds in the clinical setting, especially for the treatment of immunocompromised patients, has led to the emergence of viral resistance against most of these drugs. While resistance is not a serious issue for immunocompetent individuals, it is a real concern for immunocompromised patients, especially those with AIDS and the ones that have undergone organ transplantation. All the currently approved treatments target the viral DNA polymerase. It is clear that new drugs that are more efficacious than the present ones, are not toxic, and target a different viral function would be of great use especially for immunocompromised patients. Here, we provide an overview of the diseases caused by the herpesviruses as well as the replication strategy of the better studied members of this family for which treatments are available. We also discuss the various drugs that have been approved for the treatment of some herpesviruses in terms of structure, mechanism of action, and development of resistance. Finally, we present a discussion of viral targets other than the DNA polymerase, for which new antiviral compounds are being considered.

Improved long-term results with thymoglobuline induction therapy after cardiac transplantation: a comparison of two different rabbit-antithymocyte globulines

BACKGROUND

The aim of this retrospective single center analysis was to compare possible long-term benefits of two different rabbit-antithymocyte globuline (ATG) induction therapies after cardiac transplantation.

PATIENTS AND METHODS

A total of 484 primary cardiac transplanted patients received induction therapy with two different rabbit-ATGs (thymoglobuline: n=342, ATG-fresenius: n=142). All patients received immunosuppressive maintenance therapy with cyclosporine, azathioprine, and prednisolone. Cardiac rejection was assessed by serial endomyocardial biopsies. Surveillance of graft arteriosclerosis was performed by angiograms 1, 3, and 5 years after transplantation.

RESULTS

Five-year survival was significantly better in the thymoglobuline group (76 vs. 60%). Thymoglobuline patients had a lower rate of death from rejection (2.3 vs. 10%; P<0.01) and graft arteriosclerosis (0.88 vs. 5.6%; P<0.01). After 5 years, freedom from rejection was 72% in the thymoglobuline group compared to 42% in the ATG-fresenius group (P<0.01). Graft arteriosclerosis appeared in 14% of thymoglobuline patients and in 28% of ATG-fresenius patients (P<0.01). Viral infections occurred more often in thymoglobuline patients (53 vs. 39%, P<0.05) although there was no difference in appearance of cytomegalovirus disease (17 vs. 13%). Freedom from posttransplant malignant disease was comparable between the two groups.

CONCLUSION

These results suggest that there are differences between rabbit ATG products. The superior prevention of rejection with thymoglobuline may be the reason for the lower rate of graft arteriosclerosis.

Cytomegalovirus prophylaxis with antiviral agents for solid organ transplantation

OBJECTIVES

To assess the efficacy of antiviral agents in solid organ transplant recipients in the prevention of cytomegalovirus infection and symptomatic disease and in the reduction of the incidence of acute rejection, graft loss and death.

SEARCH STRATEGY

A computerised search was conducted on Medline, Embase and Pascal. The reference lists of the current review articles and some congress proceedings were searched manually (Transplantation Proceedings, American Thoracic Society, European Society of Organ Transplantation).

SELECTION CRITERIA

Prospective, randomised studies in adults or paediatric recipients of a solid organ transplant, in which one arm received a prophylactic treatment with acyclovir and/or ganciclovir, started before cytomegalovirus infection, and the control arm received placebo or no treatment.

DATA COLLECTION AND ANALYSIS

Data were extracted from each trial and a letter sent to the authors to ask them to verify the data extracted, and to provide any data that was missing. For each outcome, several methods were used to calculate the chi-square for association and the estimate for the treatment effect with its 95% confidence interval, with an additive model (rate difference), or a multiplicative model (odds ratio, relative risk). We considered the test of association to be significant when the p value was less than 0.01 and the homogeneity test to be significant when the p value was less than 0.1.

MAIN RESULTS

Prophylactic treatment was found to be associated with a significant decrease in cytomegalovirus disease compared with placebo or no treatment, using the logarithm of relative risk method (relative risk 0.51, 95% confidence interval 0. 41-0.64, p value for X(2) association < 0.001). Prophylactic treatment also decreased the rate of cytomegalovirus infection (RR 0. 62, 95%CI 0.53-0.73, p < 0.001). Our analysis failed to show a significant decrease in graft loss, acute rejection or death in the prophylactic treatment group. Sub-group analysis based on the type of antiviral agent (acyclovir or ganciclovir) and on the type of organ (kidney or liver) gave comparable results.

REVIEWER'S CONCLUSIONS

The use of antiviral agents for the prevention of cytomegalovirus disease and cytomegalovirus infection in solid organ transplantation is supported by this meta-analysis.

Acyclovir is phosphorylated by the human cytomegalovirus UL97 protein

Acyclovir (ACV) has shown efficacy in the prophylactic suppression of human cytomegalovirus (HCMV) reactivation in immunocompromised renal transplant patients without the toxicity associated with ganciclovir (GCV). The HCMV UL97 gene product, a protein kinase, is responsible for the phosphorylation of GCV in HCMV-infected cells. This report provides evidence for the phosphorylation of ACV by UL97. Anabolism studies with the HCMV wild-type strain AD169 and with recombinant mutants derived from marker transfer experiments performed by using mutant UL97 DNA from both clinical isolates and a laboratory-derived strain resistant to GCV showed that mutations in the UL97 gene cripple the ability of recombinant virus-infected cells to anabolize both GCV and ACV. These mutant UL97 recombinant viruses were less susceptible to both GCV and ACV than was the wild-type strain. A recombinant herpes simplex virus type 1 strain, in which the thymidine kinase gene is deleted and the UL13 gene is replaced with the HCMV UL97 gene, was able to induce the phosphorylation of ACV in infected cells. Finally, purified UL97 phosphorylated both GCV and ACV to their monophosphates. Our results indicate that UL97 promotes the selective activity of ACV against HCMV.

Two grams daily of oral acyclovir reduces the incidence of cytomegalovirus disease in CMV-seropositive liver transplant recipients

Our objective in this study was to determine the efficacy of 2 grams a day of oral acyclovir administered for 16 weeks after transplantation for the prevention of cytomegalovirus (CMV) infection and disease in CMV-seropositive liver transplant recipients. Seventy-three adult liver transplant recipients, seropositive for CMV, were randomized to receive either 2 grams a day of oral acyclovir for 16 weeks after transplantation or no prophylaxis. The incidence of CMV disease was significantly lower in the acyclovir group (5%) than in the control group (27%; P < 0.05). By log-rank analysis, the differences in the probability of presenting CMV disease over the first 16 weeks and over the 1st year were also significant (P < 0.05). We conclude that 2 grams a day of oral acyclovir provides effective prophylaxis against CMV disease in CMV-seropositive liver transplant recipients.

Infections in solid-organ transplant recipients

Solid-organ transplantation is a therapeutic option for many human diseases. Infections are a major complication of solid-organ transplantation. All candidates should undergo a thorough infectious-disease screening prior to transplantation. There are three time frames, influenced by surgical factors, the level of immunosuppression, and environmental exposures, during which infections of specific types most frequently occur posttransplantation. Most infections during the first month are related to surgical complications. Opportunistic infections typically occur from the second to the sixth month. During the late posttransplant period (beyond 6 months), transplantation recipients suffer from the same infections seen in the general community. Opportunistic bacterial infections seen in transplant recipients include those caused by Legionella spp., Nocardia spp., Salmonella spp., and Listeria monocytogenes. Cytomegalovirus is the most common cause of viral infections. Herpes simplex virus, varicella-zoster virus, Epstein-Barr virus and others are also significant pathogens. Fungal infections, caused by both yeasts and mycelial fungi, are associated with the highest mortality rates. Mycobacterial, pneumocystis, and parasitic diseases may also occur.

Characteristics of patients surviving more than ten years after cardiac transplantation

The clinical status and quality of life of 40 patients who lived or are still alive more than 10 years after transplantation at our institution were reviewed with the use of our transplant database, prospective patient examinations, cardiac catheterization, and exercise testing. Patient-perceived health status was determined with use of the Nottingham Health Profile and General Well Being examinations. Factors associated with longevity were determined by a Cox proportional hazards model. Twenty-six patients are alive and 14 have died. The mean age at transplant was 32.4 +/- 12 years and the current age (or age at death) is 46.1 +/- 12.8 years. Actuarial freedom from rejection was similar to that of patients surviving less than 10 years (p = 0.8), but freedom from all types of infection was less (p = 0.005). Immunosuppressive drugs include cyclosporine (11/26 patients), azathioprine (24/26), and prednisone (26/26, mean dose 12.7 mg/day). Catheterization hemodynamic data show well-preserved graft function at a mean follow-up of 11.7 +/- 3.3 years. Graft coronary artery disease prevalence is 51.0% +/- 8%. Exercise test results are as follows: duration 8.7 +/- 3.5 minutes (range 2 to 16 minutes), maximum heart rate/expected rate 77.3% +/- 11% (50% to 92%), maximum systolic blood pressure 171 +/- 23 mm Hg (140 to 208 mm Hg), and metabolic equivalents 9.2 +/- 2.3 units (5.5 to 12.9 units), or about 84% of predicted. Mean score on the General Well Being examination was 75.3 +/- 21.6 (normal). Nottingham Health Profile scores were nearly normal, except for in the 50- to 64-year-old age group in categories of mobility, pain, sleep quality, and energy level. Causes of death were coronary artery disease in 7 of 14, infection in 4 of 14, lymphoma in 1 of 14, and nonlymphoid cancer in 2 of 14. In the Cox regression, variables most associated with survival (t > 2.0, multivariate p = 0.0005) were age at transplantation (t = 3.26), preoperative duration of illness (t = 3.57), postoperative cytomegalovirus infection (t = 2.16), and ejection fraction at 12 months after operation (t = -2.62). We conclude that cardiac transplantation can provide patients with end-stage cardiac failure an acceptable general medical condition, functional status, and perceived quality of life well into the second decade after operation.