Randomized prospective trial of ganciclovir maintenance therapy for cytomegalovirus retinitis

Surgery for Infectious Retinitis - When Medical Therapy Is Not Sufficient: The Moacyr E. Alvaro Pan-American Lecture 2023

BACKGROUND

Viral retinitis composes a group of infectious ocular diseases with poor prognoses. With the advent of antivirals and HAART, the treatment of these diseases has evolved and ocular outcomes have improved. However, even with prompt medical treatment, a significant number of patients will experience complications that require surgical intervention. While there has been an abundance of research examining the medical treatment of CMV retinitis and acute retinal necrosis, the research examining surgical outcomes of complications such as retinitis-associated retinal detachment is comparatively limited.

METHODS

Literature review.

RESULTS

In this review, we discuss the current literature examining treatment of CMV retinitis and acute retinal necrosis, with a focus on surgical management of complications such as retinal detachment.

CONCLUSIONS

Despite significant improvements in the medical treatment of CMV retinitis and ARN over the last three decades, vision-threatening complications such as retinal detachment are relatively common and require surgical management via PPV, laser photocoagulation, and intraocular gas or silicone oil tamponade.

Anti-Herpetic Activity of (±)-(1α, 2β, 3α)-9-[2-Hydroxy-3-(Hydroxymethyl)Cyclobutyl]Guanine and Inhibition of HSV-1 DNA Polymerase

A novel nucleoside analogue, (±)-(1α, 2β, 3α)-9-[2-hydroxy -3-(hydroxymethyl)cyclobutyl]guanine [(±)-HHCG] was synthesized and has antiviral activity against herpes simplex virus (HSV) types 1 and 2, human cytomegalovirus (HCMV) and varicella-zoster virus (VZV) in plaque reduction assays. The antiviral activity of (±)-HHCG against HSV-2 shows a 10-40-fold dependence on the presence of a virally encoded thymidine kinase. (±)-HHCG is a substrate for HSV-1 thymidine kinase with a phosphorylation rate of 28 μm h−1 compared to 15 μm h−1 for acyclovir under identical conditions. Enzymatically prepared HHCG-triphosphate is a competitive inhibitor of dGTP incorporation into DNA by HSV-1 DNA polymerase with an inhibition constant corresponding to 0.0077 μm. Hybridization studies using an HSV-1-specific DNA probe indicated that DNA synthesis is reduced in HSV-1-infected WI-38 cells treated with (±)-HHCG, with an ED50 comparable to that of acyclovir. These results suggest that the antiviral activity of (±)-HHCG is due to preferential inhibition of viral DNA synthesis.

Intravitreal ganciclovir maintenance injection for cytomegalovirus retinitis: efficacy of a low-volume, intermediate-dose regimen

OBJECTIVE

To report the clinical outcomes of highly active antiretroviral therapy (HAART)-naïve, human immunodeficiency virus (HIV)-positive patients with newly diagnosed cytomegalovirus (CMV) retinitis receiving intravitreal injections of a low-volume intermediate maintenance dose (1.0 mg/0.02 ml) of ganciclovir.

DESIGN

Nonrandomized, retrospective, interventional series.

PARTICIPANTS

A consecutive cohort of 34 eyes from 24 HAART-naïve patients with AIDS and diagnosed with CMV retinitis by retinal specialists at the Singapore Communicable Disease Centre.

INTERVENTION

Patients received a maintenance dose of 1.0 mg/0.02 ml of intravitreal ganciclovir once weekly after standard induction therapy with 2.0 mg/0.04 ml of twice weekly intravitreal ganciclovir.

MAIN OUTCOME MEASURES

Time to progression, visual acuity, and complications. Progression was observed using photographic documentation.

RESULTS

The median time to progression was 152 days (mean, 380.1 days, 95% confidence interval, 240.8-519.4). The median follow-up was 95 days (mean, 207.9 days). Three eyes developed rhegmatogenous detachments, but there was no endophthalmitis after 1858 injections. Contralateral involvement of CMV retinitis occurred in 17.6% of the patients. The cost estimate for intravitreal injections over a 6-month period was 11.7% that of sustained-release implants for unilateral treatment and 11.1% that of daily continuous intravenous infusions and oral valganciclovir compared with bilateral treatments.

CONCLUSIONS

Weekly low-volume, intermediate-dose (1.0 mg/0.02 ml) ganciclovir is an efficacious option in developing countries where newer options of sustained-release implants and oral valganciclovir are unavailable or prohibitively expensive. The regimen maintains a long time to progression, preserving vision while minimizing retinal toxicity complications.

Cytomegalovirus retinitis and the acquired immunodeficiency syndrome--bench to bedside: LXVII Edward Jackson Memorial Lecture

PURPOSE

To update information on cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS) and to integrate information on its pathogenesis and clinical outcomes.

DESIGN

Literature review.

METHODS

Selected articles from the medical literature, particularly large epidemiologic studies, including the Johns Hopkins Cytomegalovirus Retinitis Cohort Study, the Longitudinal Study of the Ocular Complications of AIDS, and the Cytomegalovirus Retinitis and Viral Resistance Study, were reviewed. Clinical information is discussed in light of knowledge on CMV, its pathogenesis, and its interactions with human immunodeficiency virus (HIV).

RESULTS

Cytomegalovirus uses several mechanisms to evade the immune system and establish latent infection in immunologically normal hosts. With immune deficiency, such as late-stage AIDS, CMV reactivates, is disseminated to the eye, and establishes a productive infection, resulting in retinal necrosis. HIV and CMV potentiate each other: CMV accelerates HIV disease, and CMV retinitis is associated with increased mortality. Randomized clinical trials have demonstrated the efficacy of treatments for CMV retinitis. Systemically administered treatment for CMV retinitis decreases AIDS mortality. Highly active antiretroviral therapy (HAART) effectively suppresses HIV replication, resulting in immune recovery, which, if sufficient, controls retinitis without anti-CMV therapy. Resistant CMV, detected in the blood, correlates with resistant virus in the eye and is associated with worse clinical outcomes, including mortality. Host factors, including host genetics and access to care, play a role in the development of CMV retinitis.

CONCLUSIONS

Clinical outcomes of CMV retinitis in patients with AIDS are dependent on characteristics of the virus and host and on HIV-CMV interactions.

Mortality associated with resistant cytomegalovirus among patients with cytomegalovirus retinitis and AIDS

OBJECTIVE

To evaluate the effect of drug-resistant cytomegalovirus (CMV) on survival among patients with CMV retinitis.

DESIGN

Prospective cohort study during 1993 to 2003.

PARTICIPANTS

We included 266 patients with AIDS and newly diagnosed CMV retinitis treated with either ganciclovir or foscarnet.

METHODS

Data on ganciclovir and foscarnet resistance were obtained from blood and urine specimens collected at regular, predetermined intervals. The effect of resistant CMV on mortality was evaluated with a time-dependent Cox proportional hazard model.

MAIN OUTCOME MEASURES

Mortality.

RESULTS

The median survival of the entire cohort was 12.6 months. Analysis of risk factors for mortality demonstrated that resistant CMV was associated with an increased mortality (hazard ratio, 1.65; 95% confidence interval, 1.05-2.56; P = 0.032). Among the other parameters tested, only time since AIDS diagnosis was associated significantly with mortality, with a hazard ratio of 1.10 per year since AIDS diagnosis (P = 0.001).

CONCLUSIONS

Resistant CMV is associated with increased mortality among patients with AIDS being treated for CMV retinitis.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

HIV-associated retinopathy in the HAART era

BACKGROUND

The effectiveness of highly active antiretroviral therapy (HAART) in restoring immune function in patients with acquired immunodeficiency syndrome (AIDS) has led to changes in the incidence, natural history, management, and sequelae of human immunodeficiency virus (HIV)-associated retinopathies, especially cytomegalovirus (CMV) retinitis.

METHODS

The medical literature pertaining to HIV-associated retinopathies was reviewed with special attention to the differences in incidence, management strategies, and complications of these conditions in the eras both before and after the widespread use of HAART.

RESULTS

In the pre-HAART era, CMV retinitis was the most common HIV-associated retinopathy, occurring in 20%-40% of patients. Median time to progression was 47 to 104 days, mean survival after diagnosis was 6 to 10 months, and indefinite intravenous maintenance therapy was mandatory. Retinal detachment occurred in 24%-50% of patients annually. Herpetic retinopathy and toxoplasmosis retinochoroiditis occurred in 1%-3% of patients and Pneumocystis carinii choroiditis, syphilitic retinitis, tuberculous choroiditis, cryptococcal choroiditis, and intraocular lymphoma occurred infrequently. In the HAART era the incidence of CMV retinitis has declined 80% and survival after diagnosis has increased to over 1 year. Immune recovery in patients on HAART has allowed safe discontinuation of maintenance therapy in patients with regressed CMV retinitis and other HIV-associated retinopathies. Immune recovery uveitis (IRU) is a HAART dependent inflammatory response that may occur in up to 63% of patients with regressed CMV retinitis and elevated CD4 counts and is associated with vision loss from epiretinal membrane, cataract, and cystoid macular edema.

CONCLUSIONS

The incidence, visual morbidity, and mortality of CMV retinitis and other HIV-associated retinopathies have decreased in the era of HAART and lifelong maintenance therapy may safely be discontinued in patients with restored immune function. Patients with regressed CMV retinitis, however, may still lose vision from epiretinal membrane, cystoid macular edema, and cataract secondary to IRU.

Discontinuation of maintenance therapy for cytomegalovirus retinitis in HIV-infected patients receiving highly active antiretroviral therapy

OBJECTIVE

To study the safety of discontinuing cytomegalovirus (CMV) maintenance therapy among patients with cured CMV retinitis receiving highly active antiretroviral therapy (HAART).

METHODS

Patients with a history of CMV retinitis who were receiving anti-CMV maintenance therapy and who had a CD4 cell count > 75 x 10(6) cells/l and a plasma HIV RNA level < 30000 copies/ml while on HAART were included in a multicentre prospective study. Maintenance therapy for CMV retinitis was discontinued at enrolment and all the patients were monitored for 48 weeks by ophthalmological examinations and by determination of CMV markers, CD4 cell counts and plasma HIV RNA levels. T helper-1 anti-CMV responses were assessed in a subgroup of patients. The primary study endpoint was recurrence of CMV disease.

RESULTS

At entry, the 48 assessable patients had been taking HAART for a median of 18 months. The median CD4 cell count was 239 x 10(6) cells/l and the median HIV RNA load was 213 copies/ml. Over the 48 weeks, 2 of the 48 patients had a recurrence of CMV disease. The cumulative probability of CMV retinitis relapse was 2.2% at week 48 (95% confidence interval, 0.4-11.3) and that of all forms of CMV disease 4.2%. CMV blood markers remained negative throughout follow-up. The proportion of patients with CMV-specific CD4 T cell reactivity was 46% at baseline and 64% at week 48.

CONCLUSIONS

CMV retinitis maintenance therapy may be safely discontinued in patients with CD4 cell counts above 75 x 10(6) cells/l who have been taking HAART for at least 18 months.

Economic evaluation of systemic treatments for cytomegalovirus retinitis in patients with AIDS

OBJECTIVE

To determine the cost of using systemic therapy to treat newly diagnosed cytomegalovirus (CMV) retinitis in persons with AIDS.

DESIGN

Incidence-based simulation model of CMV treatment from a government payer perspective.

SETTING

Swiss healthcare system.

PATIENTS AND PARTICIPANTS

Patients with AIDS and newly diagnosed CMV retinitis.

INTERVENTIONS

Patients were assigned to 1 of 4 treatment regimens for induction and maintenance therapy: (i) intravenous (IV) cidofovir induction and maintenance (cidofovir IV/IV); (ii) IV foscarnet induction and maintenance (foscarnet IV/IV); (iii) IV ganciclovir induction and maintenance (ganciclovir IV/IV); and (iv) IV ganciclovir induction and oral (PO) ganciclovir maintenance (ganciclovir IV/PO). Following a second relapse, patients were assigned to one of the other regimens.

MAIN OUTCOME MEASURES

Time to first and subsequent progression, duration of maintenance treatment and direct medical expenditures [1998 Swiss francs (SwF)] .

RESULTS

The median time to first progression was longest for cidofovir IV/IV, followed by foscarnet IV/IV, ganciclovir IV/IV and ganciclovir IV/PO. Mean survival was 13 months and mean costs for this period in the base case were lowest in those initially treated with cidofovir (SwF146,742), followed by initial treatment with foscarnet IV/IV (SwF194,809), ganciclovir IV/PO (SwF195,190) and ganciclovir IV/IV (SwF243,964). Costs were most sensitive to changes in efficacy estimates.

CONCLUSIONS

Of the regimens studied, initiation of treatment with systemic cidofovir appears least costly over a 13-month period.

Cytomegalovirus viraemia has poor predictive value for the development of cytomegalovirus disease in patients with advanced HIV-infection

OBJECTIVE

Cytomegalovirus (CMV) continues to be one of the most important opportunistic infections associated with human immunodeficiency virus (HIV) infection. This study investigated the value of CMV-viraemia in predicting the development of clinical CMV disease in patients with advanced HIV infection.

METHODS

This was a prospective observational study performed over a 2-year period between 1994-96 in the Department of Infection and Tropical Medicine at Leicester Royal Infirmary. Adult HIV-positive patients attending a hospital clinic were included if they were CMV-seropositive with CD4 counts < or =50 cells/mm3. Subjects were seen at approximately 6-weekly intervals in the clinic and were reviewed by an experienced ophthalmologist. Serum for CMV PCR was taken and stored at regular intervals and qualitative and quantitative PCR was performed at the end of the study period. The value of PCR in predicting the development of CMV disease was then assessed.

RESULTS

Twenty-six patients were followed up during the study period and 77 evaluable specimens were analysed for CMV PCR. Twenty-three (30%) samples were positive and 54 negative. Seven (27%) patients developed CMV disease (five retinitis alone, and two with retinitis and oesophagitis) during the study period. Viraemia was often intermittent and there was no significant difference in the proportions of patients with positive or negative tests who subsequently developed CMV disease. The sensitivity, specificity, positive and negative predictive values of the qualitative PCR were 71%, 47%, 33% and 82% respectively and 57%, 74%, 44% and 82% respectively for the quantitative PCR (>10(3) copies/ml).

CONCLUSIONS

The results from this study, which was performed before the introduction of protease inhibitors, found that cytomegalovirus PCR was of limited clinical value in predicting the patients at greatest risk of developing CMV-disease and provided little useful prognostic information.

Comparative tolerability of therapies for cytomegalovirus retinitis

Cytomegalovirus (CMV) retinitis is a potentially sight-threatening complication of advanced HIV infection. The acute infection can be controlled with one of several therapies, including intravenous ganciclovir, foscarnet or cidofovir, slow release ganciclovir intraocular implants or serial intraocular injections of ganciclovir or foscarnet. The initial induction course of therapy is typically followed by lifelong maintenance therapy. In addition to the aforementioned treatments, oral ganciclovir and intravitreal fomivirsen injections are other options for maintenance therapy. The choice of agent must take into consideration factors such as comparative short and long term toxicity of the agents, route of administration and the possible need for indwelling catheters, administration time, cost and protection afforded against systemic dissemination of CMV infection. Possible drug interactions and additive toxicities of other agents needed for the management of the underlying HIV infection must also be taken into consideration. These factors can affect the tolerability of therapy as well as the quality of life of the patient. Relapse or progression of CMV retinitis may be caused by either inadequate drug concentrations at the site of the infection or by drug resistance. This may necessitate either an increase in drug dosage, a change in route of administration or a change to an alternative agent. All of these approaches can increase the risk of toxicity of the therapy. With the initiation of highly active antiretroviral therapy and partial reconstitution of the immune system, some patients have been able to successfully discontinue anti-CMV maintenance therapy, thereby decreasing long term drug toxicity. Determination of the patient predictors of success of this approach is an active area of research.

Discontinuing anticytomegalovirus therapy in patients with immune reconstitution after combination antiretroviral therapy

PURPOSE

To describe our experience with discontinuation of anticytomegalovirus maintenance therapy in patients who have had immune reconstitution after initiation of highly active antiretroviral therapy.

METHODS

Fifteen patients with treated cytomegalovirus retinitis, who had immune reconstitution after initiation of highly active retroviral therapy, had anticytomegalovirus maintenance therapy discontinued. Patients were followed closely for relapse of retinitis.

RESULTS

Median nadir CD4+ T-cell count, before institution of highly active antiretroviral therapy, was 20 cells/microl. At the time of discontinuation of anticytomegalovirus therapy, median CD4+ T-cell count was 297 cells/microl. Patients were followed for a median of 8 months off anticytomegalovirus therapy (range, 3 to 16 months). The median CD4+ T-cell count at last follow-up was 267 cells/microl. No patient off anticytomegalovirus therapy relapsed.

CONCLUSION

In selected patients with immune reconstitution after initiation of highly active antiretroviral therapy, anticytomegalovirus therapy may be safely discontinued, at least temporarily. Longer follow-up of these patients is needed to determine how long such therapy may be interrupted, and when anticytomegalovirus therapy should be reinstituted.

Cytomegalovirus polymerase chain reaction viraemia in patients receiving ganciclovir maintenance therapy for retinitis

OBJECTIVES

To determine whether recurrence of polymerase chain reaction (PCR) viraemia during maintenance ganciclovir for cytomegalovirus (CMV) retinitis correlates with (i) CMV disease at a new anatomical site, (ii) progression of the presenting retinitis, or (iii) acquisition of genetic changes in gene UL97 associated with resistance to ganciclovir.

DESIGN

A previously described cohort of 45 patients presenting with first episode retinitis was followed clinically using ophthalmoscopy and serial tests for PCR viraemia for a median of 7 months. CMV viral load and genetic markers of ganciclovir resistance were measured in PCR-positive samples.

METHODS

PCR amplification of the glycoprotein B region of CMV and quantitative competitive PCR assays were employed. Genetic changes in UL97 were identified by sequencing/point mutation assay.

RESULTS

PCR viraemia correlated significantly with new episodes of CMV disease (P=0.011) and a trend was seen for the association with progression of retinitis (P=0.07). Amongst the 14 patients PCR-positive during maintenance ganciclovir, 10 (71%) had genetic markers of resistance. None of these patients became PCR-negative in blood after reinduction ganciclovir therapy compared with three out of four without markers of resistance (P=0.022).

CONCLUSIONS

CMV PCR viraemia correlated strongly with the development of new episodes of CMV disease. Most patients with progression of retinitis remained PCR-negative in blood, consistent with therapeutic failure due to poor intraocular penetration of ganciclovir. However, the minority who were PCR-positive in blood may have reinfected their eye, and frequently had markers of ganciclovir resistance. The implications of these findings for the management of patients with CMV disease are discussed.

Predictors of cytomegalovirus disease, natural history and autopsy findings in a cohort of patients with AIDS

OBJECTIVE

To identify the predictors of acquiring cytomegalovirus (CMV) disease, and to describe natural history, therapeutic management and autopsy findings in affected patients.

DESIGN

Observational study of a consecutive cohort of AIDS patient diagnosed and followed in the same institution.

METHODS

All of the patients with CMV were included. Statistical analyses were performed to establish the risk of acquiring the disease at or after AIDS presentation, survival, and the occurrence and time of relapses in relation to maintenance therapy. The presence of CMV infection at autopsy was also investigated.

RESULTS

CMV disease was diagnosed in 304 (24.8%) out of 1,227 patients, its incidence increasing according to the year of AIDS diagnosis. Women, homosexual men, patients given zidovudine and Pneumocystis carinii pneumonia (PCP) prophylaxis before AIDS, and severely immunodepressed patients were at higher risk for the disease. CMV disease was an independent factor of worse survival (hazard ratio, 1.7 versus PCP; 95% confidence intervals, 1.28-2.13). Patients untreated during the acute phase had a 4.3 higher risk of dying than those treated. Relapses occurred less frequently and later in patients given continuous maintenance treatment (23 out of 113; 17 months) than in untreated patients (13 out of 16; 3 months) or those given discontinuous therapy (22 out of 40; 7 months), whereas survival was independent from treatment. CMV infection was found in 97 out of 134 patients at autopsy, but was unassociated with relapse.

CONCLUSIONS

CMV is a severe disease whose frequency is higher in severely immunodepressed patients. Continuous treatment leads to a lower relapse rate even if it does not change survival or eradicate the infection.

Drug treatment of HIV-related opportunistic infections

The AIDS epidemic has led to the emergence of several disease entities which in the pre-AIDS era were rare or seemingly innocuous. Experience of treating these diseases varies. In some instances, such as Pneumocystis carinii pneumonia, there is an abundance of published literature to direct our course of action. However, for many of these newly recognised diseases our treatment experience is limited. Furthermore, in many instances, well controlled trials evaluating treatment modalities in the AIDS population are lacking. We have identified 13 disease entities (P. carinii pneumonia, toxoplasmosis, cryptococcosis, histoplasmosis, Mycobacterium tuberculosis, Mycobacterium avium complex, cytomegalovirus, coccidioidomycosis, isosporiasis, candidosis, Kaposi's sarcoma, herpes simplex virus, and varicella zoster virus) and have reviewed the current literature with regard to their treatment.

Summary of the International Consensus Symposium on Advances in the Diagnosis, Treatment and Prophylaxis and Cytomegalovirus Infection

CMV infection and CMV disease can be difficult to differentiate and the diagnosis is usually based on a compatible clinical picture and the results of a diagnostic test for CMV. The only exception to this rule is in HIV-infected patients where fundoscopy is sufficient to diagnose CMV retinitis. Of the current diagnostic tests, qualitative and quantitative PCR, branched DNA and Hybrid Capture, are the most promising. The pp65 antigenemia assay has the disadvantage of being more labor-intensive than the DNA based tests. Preliminary data show that a positive qualitative PCR in a HIV-infected patient has a predictive value for the development of CMV retinitis. However, of the patients positive by qualitative PCR, those with high viral loads in quantitative PCR were at the greatest risk of CMV disease. This might make it possible to identify with great certainty the patients who will go on to develop CMV retinitis, thereby decreasing the number of patients eligible for preemptive or prophylactic therapy and increasing the cost-benefit of this therapeutic measure. Quantitative test might also be useful in monitoring response to therapy, but randomized trials comparing the test are needed. Prophylactic antiviral agents should not be used in seronegative transplant recipients receiving organs from seronegative donors. In high-risk transplant recipients, ganciclovir should be used. CMV vaccines are useful for the protection of babies from CMV seronegative mothers against congenital CMV disease. It also may be useful in seronegative transplant recipients receiving a seropositive donor organ, although the benefit of chemo prophylaxis may surpass that of vaccine. HIV-infected patients with CMV retinitis who relapse under either ganciclovir or foscarnet benefit from subsequent combination therapy, rather than switching to the other drug. However, the cost is high in terms of quality of life. Intravitreal therapy for CMV retinitis is very efficacious, suggesting that drug delivery is a problem in systemic therapy. However, intravitreal therapy does not protect against the development of CMV retinitis in the contralateral eye or from CMV disease elsewhere. Therefore, systemic therapy should be added. CMV disease of the CNS should be diagnosed early and treated agressively, possible with combination therapy. A diagnosis of CMV disease should be based on a compatible clinical picture and the demonstration of CMV in CSF by DNA or antigen assays which are more sensitive than culture.

Intravitreal ganciclovir for cytomegalovirus retinitis in patients with AIDS

OBJECTIVE

To assess the evolution of cytomegalovirus (CMV) retinitis and evaluate the possible complications associated with the use of intravitreal injections to treat this disease.

DESIGN

A nonrandomized, retrospective study with case series was performed. The study took place over 34 months.

SETTING

The study included patients with AIDS who developed CMV retinitis, and who were treated in the hospital, as outpatients, or both.

PATIENTS

Twelve patients with AIDS and CMV retinitis diagnosed between June 1990 through April 1993 were included in the study. MAIN PATIENT PARAMETERS AND OUTCOME MEASURES: For each patient, the following data were recorded: age, risk factors, other systemic findings, dates of AIDS and CMV retinitis diagnoses, stage of AIDS, extent of the retinitis, CD4 lymphocyte count at the time of diagnosis of retinitis, visual acuity, clinical evolution of the ocular infection, therapy, complications caused by the treatment, development on nonocular CMV, and the use of zidovudine or didanosine during the study period.

RESULTS

Vision improved or remained stable in nine patients and worsened in three. Two patients developed optic neuritis. The retinitis progressed to the other eye in only one of the eight patients who had unilateral involvement. The rate of relapse with maintenance therapy was 8.3% (n = 1) within the first 8 weeks. Treatment was well tolerated. There was no evidence of toxicity after a total of 226 intravitreal ganciclovir injections. All patients were able to tolerate zidovudine or didanosine concomitantly with intravitreal ganciclovir.

CONCLUSIONS

Intravitreal ganciclovir appears to be an effective alternate to systemic ganciclovir in patients with severe neutropenia and in patients who choose to continue receiving systemic zidovudine or didanosine. Early treatment and long-term maintenance therapy is essential for preserving sight.

Oral ganciclovir as maintenance treatment for cytomegalovirus retinitis in patients with AIDS. Syntex Cooperative Oral Ganciclovir Study Group

BACKGROUND

Cytomegalovirus retinitis, a sight-threatening infection associated with the acquired immunodeficiency syndrome (AIDS), currently requires lifelong intravenous treatment. An effective oral treatment would be an important advance.

METHODS

We compared oral with intravenous ganciclovir in an open-label, randomized study in patients with AIDS and newly diagnosed, stable cytomegalovirus retinitis (the disease was stabilized by three weeks of treatment with intravenous ganciclovir). Sixty subjects were randomly assigned to maintenance therapy with intravenous ganciclovir at a dose of 5 mg per kilogram of body weight daily, and 63 to maintenance therapy with oral ganciclovir at a dose of 3000 mg daily. The subjects were followed for up to 20 weeks, with photography of the fundi conducted every other week. The photographs were evaluated at the completion of the study by an experienced grader who was unaware of the subjects' treatment assignments.

RESULTS

Efficacy could be evaluated in 117 subjects; photographs were ungradable for 2 of the 117. On the basis of the masked assessment of photographs from 115 subjects, the mean time to the progression of retinitis was 62 days in those given intravenous ganciclovir and 57 days in those given oral ganciclovir (P = 0.63; relative risk [oral vs. intravenous], 1.08; 95 percent confidence interval for the difference in means, -22 to +12 days). On the basis of funduscopy by ophthalmologists who were aware of the subjects' treatment assignments, the mean time to progression was 96 days in subjects given intravenous ganciclovir and 68 days in subjects given oral ganciclovir (P = 0.03; relative risk [oral vs. intravenous], 1.68; 95 percent confidence interval for the difference in means, -45 to -11 days). Survival, changes in visual acuity, the incidence of viral shedding, and the incidence of adverse gastrointestinal events were similar in the two groups. Neutropenia, anemia, intravenous-catheter-related adverse events, and sepsis were more common in the group given intravenous ganciclovir.

CONCLUSIONS

Oral ganciclovir is safe and effective as maintenance therapy for cytomegalovirus retinitis and is more convenient for patients to take than intravenous ganciclovir.

Ganciclovir. An update of its therapeutic use in cytomegalovirus infection

The antiviral nucleoside analogue ganciclovir has demonstrated in vitro activity against human cytomegalovirus and effectively treats infection caused by this organism in various immunocompromised patient groups. The drug prolongs time to progression in patients with acquired immune deficiency syndrome (AIDS)-related cytomegalovirus retinitis although life-long maintenance therapy is required. Direct comparisons between ganciclovir and foscarnet in this indication are few; nevertheless, the 2 drugs appear to have equal therapeutic efficacy in treating cytomegalovirus retinitis although results from 1 study in this indication suggest that foscarnet has an advantage in terms of patient survival. AIDS-related gastrointestinal and, to a lesser extent, pulmonary cytomegalovirus infection also respond to treatment with ganciclovir; maintenance therapy does not appear to be required in these latter 2 indications. Ganciclovir is also useful against cytomegalovirus infection in organ transplant recipients. The drug is most effective when given prophylactically or as early treatment for asymptomatic infection in bone marrow transplant recipients; treatment of established infection is less effective in this patient group. However, established infection in solid organ transplant recipients appears to respond to treatment with ganciclovir. The most common adverse event during ganciclovir therapy is haematological toxicity but this appears to be readily reversible on discontinuation of the drug. In addition, coadministration of granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage CSF (GM-CSF) has been shown to prevent ganciclovir-associated neutropenia. Thus, ganciclovir is a valuable treatment for cytomegalovirus infection in patients with AIDS and in organ transplant recipients. Further studies comparing ganciclovir and foscarnet-ideally incorporating the use of G-CSF or GM-CSF to prevent ganciclovir-associated neutropenia and assessing survival as 1 endpoint--should further clarify the relative role of ganciclovir as treatment or prophylaxis for cytomegalovirus infection.

Combined daily therapy with intravenous ganciclovir and foscarnet for patients with recurrent cytomegalovirus retinitis

We treated seven patients (nine eyes) who had cytomegalovirus retinitis with daily intravenous ganciclovir plus foscarnet. All patients had demonstrated multiple progressions of retinitis on single-drug therapy, and some were intolerant to induction doses of one or both medications. Before combination therapy, the median number of progressions was five per patient. The mean interval between progressions was 11 weeks, and the mean interval before the final progression was four weeks. While taking combination therapy, two patients showed progression after 14 and 34 weeks. Two patients showed no progression after 17 and 36 weeks of follow-up. Three patients died after five, 14, and 23 weeks, respectively, without progression of retinitis. In every patient, the progression-free interval was longer during combination therapy than the previous progression-free interval during single-drug therapy. In no case was combination therapy stopped because of toxicity. Combination therapy was fairly well tolerated and appeared to prolong the interval to progression and to preserve vision in our patients.

Foscarnet and ganciclovir combination therapy for CMV disease in HIV-infected patients

An open prospective trial of combined ganciclovir and foscarnet therapy for 3 weeks was initiated in 14 episodes of severe CMV-disease in 13 HIV-infected patients (all CDC class IV, age 30-42, median 34 years, CD4+ cell count 0-80, median 10/microliters). In seven episodes of gastrointestinal disease (five colitis, two esophagitis) remission of symptoms and mucosal changes was achieved in five. In seven episodes of retinitis, scarring was achieved in six. Renal toxicity was seen in two patients, moderate hematologic toxicity in eight patients. Overall efficacy was comparable to monotherapy; no new toxicities were seen with the combination of these two drugs.

Pathology of cytomegalovirus retinitis treated with sustained release intravitreal ganciclovir

BACKGROUND

An experimental sustained release intraocular device has been designed to deliver ganciclovir over a long period of time. As part of an efficacy trial, the ganciclovir intraocular device was used to treat cytomegalovirus (CMV) retinitis in patients with acquired immune deficiency syndrome (AIDS).

METHODS

All patients had active CMV retinitis that had progressed despite intravenous ganciclovir therapy. The ganciclovir intraocular device was inserted into the vitreous cavity by making an inferotemporal full-thickness circumferential sclerotomy and anchored to the incision. Intravenous therapy was then discontinued and patients were followed up at 2-week intervals until death. Seven eyes from five patients were obtained 2 to 10 hours postmortem and submitted for histopathologic examination. Light and electron microscopic studies were performed and correlated to the clinical outcome. Follow-up period after device placement ranged from 16 to 82 days (median, 70 days).

RESULTS

All seven eyes showed clinical stabilization of the CMV retinitis. Light microscopy showed varying degrees of retinal atrophy with areas of gliosis. In addition, we observed syncytial megalic cells containing Cowdrey type A inclusions affecting all layers of the retina. Concurrent choroidal infections with Pneumocystis carinii (1) and Mycobacterium avium (2) also were seen. Electron microscopy showed virus particles located mostly at the junction of uninvolved and "healed" retinitis. No evidence of retinal toxic effects or inflammation at the site of ganciclovir intraocular device implant was noted.

CONCLUSION

The ganciclovir intraocular device appeared to be effective in controlling the progression of CMV retinitis. The clinical and pathologic results are similar to those observed in the eyes of patients with intravenously administered ganciclovir. The lack of toxic effects and sustained levels of intravitreal ganciclovir may provide an improved therapeutic method of local treatment of CMV retinitis.

Ocular complications of the acquired immunodeficiency syndrome. Focus on the treatment of cytomegalovirus retinitis with ganciclovir and foscarnet

The most common ocular complication in patients with the acquired immunodeficiency syndrome (AIDS) is cytomegalovirus retinitis. Incidence figures vary from 20 to 76%. Patients with cytomegalovirus may suffer from mild visual impairment of one or both eyes, but as the disease progresses the retinitis will almost certainly lead to blindness. Although cytomegalovirus retinitis is not a life-threatening infection, it can largely diminish the patient's quality of life. Clinical trials for the treatment of cytomegalovirus retinitis with a number of antiviral drugs have resulted in two drugs of choice, ganciclovir and foscarnet. Both drugs have an initial efficacy with induction therapy of 80-90%, but maintenance therapy is always needed to prevent a relapse. To exclude systemic side-effects of ganciclovir, intravitreal administration has been investigated with good results. Combination therapy of foscarnet and ganciclovir may be worthwhile in resistant cytomegalovirus retinitis.

AIDS: Part II

Great strides have been made in the therapy of human immunodeficiency virus (HIV) infection. Currently approved drugs include zidovudine and didanosine. A third drug, dideoxycytidine (zalcitibine), has recently been filed for approval with the Food and Drug Administration. All these drugs work through inhibition of the reverse transcriptase enzyme. Zidovudine is the only drug that has shown clinical efficacy against HIV. Treatment of patients with advanced HIV disease (i.e., acquired immune deficiency syndrome [AIDS] or symptomatic infection with < 200 CD4+ lymphocytes per mm3), results in a prolongation and improved quality of life. Zidovudine is the only antiretroviral agent approved for the treatment of asymptomatic patients. Early intervention with zidovudine has been shown to delay progression to AIDS when patients' CD4+ lymphocyte counts decline to less than 500/mm3, irrespective of clinical signs or symptoms of HIV infection. Didanosine is currently indicated for the treatment of patients with advanced HIV disease who are intolerant to or failing zidovudine therapy. The major toxicity of zidovudine is bone marrow suppression with anemia and granulocytopenia (which occurs in from 1% to 45% of patients, depending on the clinical stage of disease and the dose of the drug). Didanosine and zalcitibine have both been associated with a severe peripheral neuropathy, which is generally reversible on cessation of the drug. In addition, didanosine has been implicated as a cause of pancreatitis that has been fatal in a small percentage of cases. The toxicities of didanosine and zalcitibine range from 1% to 10%, depending on dose, duration of therapy, and the presence of underlying HIV-related peripheral neuropathy or a previous history of pancreatitis. The clinical hallmark of HIV infection is the development of opportunistic infections and malignancies, which are a consequence of the profound immunodeficiency. The risk of an opportunistic infection increases significantly as the T-helper lymphocyte count declines to less than 20%, or 200 to 250/mm3. The spectrum of opportunistic infections ranges from viruses to protozoa. Patients with advanced HIV disease are also at increased risk of infection with nonopportunistic, community-acquired pathogens. Primary and secondary prophylaxis against the most common AIDS-defining opportunistic infection, Pneumocystis carinii pneumonia, is now recommended. Studies are currently underway to determine the efficacy of prophylaxis against other opportunistic pathogens. Treatment of opportunistic infections associated with AIDS has improved significantly over the past 5 years as new drugs and combination regimens of antimicrobials have been developed.(ABSTRACT TRUNCATED AT 400 WORDS)

Systemic antiviral drugs used in ophthalmology

Over the past two decades, the recognition of viral enzymes and proteins that can serve as molecular targets of drugs has revolutionized the treatment of viral infections. Beginning with acyclovir, a number of systemically administered agents which are both relatively safe and effective for the treatment of herpetic infections and human immunodeficiency virus (HIV) infections have become widely available. Because of increased numbers of herpes virus infections, as well as the rising epidemic of HIV infections, the ophthalmologist is, more likely than ever before to be involved in the treatment of severe and frequent ocular infections caused by herpes viruses. In addition, the acute retinal necrosis (ARN) syndrome has been demonstrated to be caused by herpes viruses and a once rare retinal infection caused by cytomegalovirus is common in patients with the acquired immunodeficiency syndrome (AIDS). In this article, four systemic antiviral drugs (Vidarabine, Acyclovir, Ganciclovir, and Foscarnet) that have demonstrated usefulness in the treatment of ophthalmic disease are reviewed in detail with regard to their mechanisms, applications, effectiveness, and side effects.

Treatment of aggressive cytomegalovirus retinitis with ganciclovir in combination with foscarnet in a child infected with human immunodeficiency virus

Ganciclovir and foscarnet are both effective for cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome, but the benefits of either agent given alone are limited. A child infected with human immunodeficiency virus who had cytomegalovirus retinitis that progressed despite treatment with either agent alone received the combination of ganciclovir and foscarnet. This treatment resulted in a sustained clinical response.

Maintenance therapy for cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome: foscarnet

The use of ganciclovir in the treatment of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS) is limited by marrow toxicity and by the development of resistance to this agent in CMV strains capable of causing progressive disease. Foscarnet retains activity against ganciclovir-resistant CMV and has an adverse effect profile different from that of ganciclovir. Preliminary data from studies conducted under the AIDS Clinical Trials Group (ACTG) program indicate that intravenous foscarnet maintenance therapy at 60, 90, and 120 mg/kg/day in AIDS patients with CMV retinitis successfully completing foscarnet induction therapy is associated with median times to retinitis progression of 90, 95, and greater than 123 days, respectively. An ACTG trial of foscarnet in patients failing ganciclovir therapy has been initiated, as has a trial jointly sponsored by the National Eye Institute and the National Institute of Allergy and Infectious Diseases comparing the safety and efficacy of foscarnet and ganciclovir. Also underway is a trial evaluating the effects of combination and alternating regimens of these two agents.

Antiviral agents

In recent years, the antiviral armamentarium has expanded considerably. Currently available agents are virustatic, inhibiting specific steps in the process of viral replication. No agent is active against nonreplicating or latent viruses. Acyclovir is useful in the treatment of genital herpes, herpes simplex encephalitis, mucocutaneous herpetic infection, varicella infection in the immunosuppressed host, and herpes zoster infection in the normal and the immunosuppressed host. It can also be used for prevention of herpesvirus infection in immunocompromised patients. Ganciclovir is indicated for the treatment of cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome (AIDS) and is effective in the management of organ-specific cytomegalovirus infection in other immunocompromised patients. Chronic hepatitis C and condyloma acuminatum due to human papillomavirus respond to therapy with interferon alfa-2b. Patients with human immunodeficiency virus infection and CD4 lymphocyte counts of less than 500 cells/mm3 should be treated with zidovudine. Amantadine is useful in a therapeutic and prophylactic role in the management of influenza A virus infection. With the expanded use of and indications for antiviral therapy, clinically significant resistance to these agents has been encountered with increasing frequency.

Efficacy and tolerance of intravitreal ganciclovir in cytomegalovirus retinitis in acquired immune deficiency syndrome

Forty-four patients with acquired immune deficiency syndrome with cytomegalovirus (CMV) retinitis (64 eyes) intolerant of or refusing systemic antiviral therapy received 710 intravitreal injections of ganciclovir at the dosage of 400 micrograms per injection. The patients were followed for a mean period of 9 weeks. Induction therapy consisted of two injections a week until healing. Maintenance therapy consisted of one injection a week until relapse. All but 1 of 53 induction courses led to cicatrization, after a mean of 6.6 injections. In 54 maintenance courses, the 8-week relapse rate was 53%. During intravitreal therapy, involvement of the fellow eye occurred in 11% of the patients and CMV infection developed in a nonocular site in 16% of the patients. Five retinal detachments and two intravitreal hemorrhages occurred. No endophthalmitis or cataract was noted. Intravitreal ganciclovir appears to be a safe and effective alternative in patients intolerant of intravenous anti-CMV drugs.

[Progressive cytomegalovirus encephalitis in successful ganciclovir therapy of cytomegalovirus retinitis in an AIDS patient]

We describe a case of an HIV-infected intravenous drug-abuser who died of progressive cytomegalovirus encephalitis despite successful treatment of cytomegalovirus retinitis with ganciclovir. On autopsy, complete remission of retinitis and widespread cytomegalovirus-encephalitis could be demonstrated. Therapeutic failure therefore seems attributable to insufficient CNS-distribution of ganciclovir rather than to ganciclovir-resistant cytomegalovirus strains.

Low frequency maintenance ganciclovir for cytomegalovirus retinitis

45 patients on maintenance ganciclovir for treated cytomegalovirus (CMV) retinitis were reviewed retrospectively. Treatment was given at 30 mg/kg/week in 3 divided doses: Monday, Wednesday, Friday. The median time to clinical relapse was 5.4 months. This is similar to that reported with higher frequency maintenance regimens. The high degree of immunodeficiency (median CD4 count 16 cells/microliters) and poor prognosis (median survival 8.2 months) associated with CMV retinitis were confirmed.

Perspectives in antiviral chemotherapy

The current progress in antiviral therapy is related to our better understanding of the viral multiplication, with potential targets for specific antiviral action at each step of the multiplication cycle inside the infected cell. Amantadine and Rimantadine are anti-influenza A drugs interfering with the penetration and the release of the virus. Most of the other antiviral drugs which are clinically available have the same target in common, namely the viral DNA polymerase. This holds true for modified nucleosides such as Acycloguanosine (Acyclovir), DHPG, Adenine-Arabinoside, Azidothymidine as well as pyrophosphate derivatives such as phosphonoformic acid. Unfortunately the antiviral chemotherapy must confront 3 obstacles: 1) a possible interference with the normal cellular metabolism, leading to residual cytotoxic side effects; 2) the genetic variability of the viruses, producing drug-resistant mutants and 3) the inability of any antiviral chemotherapeutic agent known to date to eradicate latent viral infection. A new approach of the control of latent infection is suggested with anti sense oligonucleotides of hybridons.

Ganciclovir. A review of its antiviral activity, pharmacokinetic properties and therapeutic efficacy in cytomegalovirus infections

Ganciclovir is a nucleoside analogue with antiviral activity in vitro against members of the herpes group and some other DNA viruses. It has demonstrated efficacy against human cytomegalovirus infections and should be considered a first-line therapy in the treatment of life- or sight-threatening cytomegalovirus infection in immunocompromised patients. Clinical efficacy varies with the underlying aetiology of immunocompromise and the site of disease, and prompt diagnosis and early treatment initiation appear to improve the response. In patients with cytomegalovirus pneumonia, particularly bone marrow transplant recipients, concomitant administration of cytomegalovirus immune globulin may significantly improve clinical outcome. Maintenance therapy to prevent recurrence is usually required by bone marrow transplant recipients until the recovery of adequate immune function, whereas AIDS patients may require indefinite ganciclovir maintenance therapy to prevent disease progression, as ganciclovir (like other antivirals) does not eradicate latent viral infection. Haematological effects occur relatively frequently during ganciclovir administration but are usually reversible. Ganciclovir has not been directly compared with other antiviral drugs because of the absence until recently of other effective treatments. However, comparative studies with foscarnet, particularly in cytomegalovirus retinitis, will be of considerable interest. Thus, ganciclovir represents a major advance in the therapy of severe cytomegalovirus infections in immunocompromised patients. Comparative studies, and investigation of ways of reducing toxicity (intravitreal administration; concomitant use of stimulants of haematopoiesis; use in conjunction with other antivirals with differing mechanisms of action), may further expand its eventual role.

Cytomegalovirus cultures during maintenance DHPG therapy for cytomegalovirus (CMV) retinitis in acquired immunodeficiency syndrome (AIDS)

Nine patients with acquired immunodeficiency syndrome (AIDS) and cytomegalovirus (CMV) retinitis on maintenance therapy with ganciclovir: 9(1,3-dihydroxy-2-propoxymethyl) guanine (DHPG) at high dose (30 mg/kg/week) or low dose (20 mg/kg/week) were tested every 1-2 weeks for CMV isolation from blood, saliva, and urine. Duration of therapy ranged from 1.5 to 12 months (average 5.3 months). During pretreatment and low-dose and high-dose maintenance therapy, CMV was isolated from 48/59 (81%), 90/211 (43%), and 40/290 (14%) of specimens, respectively. Three patients with progressive retinitis had viraemia more frequently than did six patients with stable retinitis, CMV being isolated from 29/47 (62%) and 17/121 (14%) of blood samples, respectively.

(+-)-(1 alpha,2 beta,3 alpha)-9-[2,3-bis(hydroxymethyl)-cyclobutyl] guanine [(+-)-BHCG or SQ 33,054]: a potent and selective inhibitor of herpesviruses

(+-)-(1 alpha,2 beta,3 alpha)-9-[2,3-bis(hydroxymethyl)cyclobutyl] guanine [(+-)-BHCG or SQ 33,054] is a newly synthesized nucleoside analog with potent and selective antiviral activity against members of the herpesvirus group, including human cytomegalovirus. The activity against a thymidine kinase deficient HSV-2 mutant was 25-fold poorer than against the parent virus, suggesting that phosphorylation is an important prerequisite for antiviral activity against HSV-2. (+-)-BHCG is readily phosphorylated by purified HSV-1 thymidine kinase, and BHCG triphosphate synthesized enzymatically is a selective inhibitor of HSV-1 DNA polymerase. (+-)-BHCG did not inhibit host cell growth at concentrations at least 1000-fold higher than HSV-2 inhibitory concentrations. Subcutaneous administration of (+-)-BHCG was protective against HSV-1 systemic infections in mice. BHCG is an exciting antiviral agent and represents a new class of nucleoside analogs.