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

Evolution of Intravitreal Therapy for Retinal Diseases-From CMV to CNV: The LXXIV Edward Jackson Memorial Lecture

PURPOSE

To present the evolution of intravitreal therapy for retinal diseases and its impact on clinical practice.

DESIGN

Retrospective literature review and personal perspective.

METHODS

Retrospective literature review and personal perspective.

RESULTS

Pharmacotherapeutic advances in retinal disease have been remarkable over the last 25 years. Almost all of the new drugs developed have required intravitreal administration to be highly effective, leading to an exponential increase in the annual number of intravitreal injections given. The use of intravitreal antibiotic injections to treat endophthalmitis, usually on a one-time basis, first familiarized ophthalmologists with this method of drug delivery. Ganciclovir was the first widely available, relatively inexpensive compounded drug that was used for repeat intravitreal injection to treat a chronic retinal disease, followed by triamcinolone for diabetic macular edema and bevacizumab for neovascular age-related macular degeneration. Ganciclovir was formulated for sustained-release drug delivery to avoid frequent intravitreal injections, a goal that has been more elusive for anti-VEGF drugs. Political obstacles encountered while conducting some of the trials to evaluate these treatments were substantial. Addressing the issues they raised led to important national policy changes that will impact the conduct of future clinical trials. The first comparative efficacy trial of intravitreal therapies was the Comparison of AMD Treatments Trials (CATT). The primary results from CATT and the many publications that followed continue to shape the use of intravitreal therapy today.

CONCLUSION

Intravitreal therapy has proven highly effective for the treatment of many retinal diseases. The treatment burden for patients from numerous injections, the cost to health care systems, and the impact on workflows in clinical practice have been substantial. Efforts to develop effective intravitreal therapies with reduced treatment burden and cost are ongoing.

Cytomegalovirus retinitis in the post-cART era

Purpose of review

To review the epidemiology, diagnosis, and management of cytomegalovirus retinitis (CMVR) in the post-combined antiretroviral era (cART) era.

Recent findings

Although cART has dramatically reduced CMVR incidence and morbidity in the HIV population, CMVR continues to cause significant vision loss in both HIV and non-HIV patients, especially amongst patients without immune reconstitution. Advances in imaging including ultra-widefield fundus and autofluorescence imaging, optical coherence tomography, and adaptive optics may reflect CMVR activity; however, the diagnosis remains a clinical one. There have been minimal advances in therapy, with several agents no longer available due to market concerns.

Summary

Despite reduced incidence and morbidity in the post-cART HIV population, CMVR continues to cause vision loss amongst HIV and non-HIV patients. Diagnosis remains primarily clinical, and therapy centers upon immune reconstitution along with systemic and/or intravitreal antivirals. Further studies are necessary to determine whether advanced imaging can influence management, and whether novel antiviral agents or adoptive immune transfer have a role in treatment of drug-resistance CMVR.

Ganciclovir

Ganciclovir is synthetic nucleoside analog of guanine closely related to acyclovir but has greater activity against cytomegalovirus. This comprehensive profile on ganciclovir starts with a description of the drug: nomenclature, formulae, chemical structure, elemental composition, and appearance. The uses and application of the drug are explained. The methods that were used for the preparation of ganciclovir are described and their respective schemes are outlined. The methods which were used for the physical characterization of the dug are: ionization constant, solubility, X-ray powder diffraction pattern, crystal structure, melting point, and differential scanning calorimetry. The chapter contains the spectra of the drug: ultraviolet spectrum, vibrational spectrum, nuclear magnetic resonance spectra, and the mass spectrum. The compendial methods of analysis of ganciclovir include the United States Pharmacopeia methods. Other methods of analysis that were reported in the literature include: high-performance liquid chromatography alone or with mass spectrometry, electrophoresis, spectrophotometry, voltammetry, chemiluminescence, and radioimmunoassay. Biological investigation on the drug includes: pharmacokinetics, metabolism, bioavailability, and biological analysis. Reviews on the methods used for preparation or for analysis of the drug are provided. The stability of the drug in various media and storage conditions is reported. More than 240 references are listed at the end of the chapter.

Detection of Two Drug-Resistance Mutants of the Cytomegalovirus by High-Resolution Melting Analysis

BACKGROUND

Human cytomegalovirus (CMV) is an opportunistic pathogen that can be treated with ganciclovir. Mutations in the UL97 gene of CMV render the virus ganciclovir resistance. These include H520Q and C603W mutations, against which we developed a novel genotyping assay for their identification.

METHODS

PCR reactions were performed to amplify fragments of the UL97 gene containing H520Q or C603W mutations. High resolution melting analysis (HRMA) coupled with unlabeled DNA probes was employed to identify the shift in melting temperature of the probe-template complex, which reflexes the presence of point mutations.

RESULTS

Melting point analysis performed on the dimeric DNA of PCR products of UL97 gene could not identify mutations in the gene. When coupled to unlabeled probes, point mutations in UL97 can be identified by analyzing the melting curve of probe-template complex. When WT and mutant UL97 DNAs were mixed together to mimic heterogeneous viral population in clinical samples, the genotyping assay is sensitive enough to detect H520Q and C603W mutants that constitute 10% of total DNA input.

CONCLUSION

Probe-based HRMA is effective in detecting H520Q and C603W mutations in the UL97 gene of CMV.

The cost-effectiveness of improved hepatitis C virus therapies in HIV/hepatitis C virus coinfected patients

OBJECTIVES

To evaluate the effectiveness and cost-effectiveness of strategies to treat hepatitis C virus (HCV) in HIV/HCV coinfected patients in the United States.

PARTICIPANTS

Simulated cohort of HIV/HCV genotype 1 coinfected, noncirrhotic, HCV treatment-naive individuals enrolled in US HIV guideline-concordant care.

DESIGN/INTERVENTIONS

Monte Carlo simulation comparing five strategies: no treatment; dual therapy with pegylated-interferon (PEG) and ribavirin (RBV); 'PEG/RBV trial' in which all patients initiate dual therapy and switch to triple therapy upon failure; 'IL28B triage' in which patients initiate either dual therapy or triple therapy based on their IL28B allele type; and PEG/RBV and telaprevir (TPV) triple therapy. Sensitivity analyses varied efficacies and costs and included a scenario with interferon (IFN)-free therapy.

MAIN MEASURES

Sustained virologic response (SVR), life expectancy, discounted quality-adjusted life expectancy (QALE), lifetime medical costs, and incremental cost-effectiveness ratios (ICERs) in $/quality-adjusted life years (QALY) gained.

RESULTS

'PEG/RBV trial,' 'IL28B triage,' and 'triple therapy' each provided 72% SVR and extended QALE compared with 'dual therapy' by 1.12, 1.14, and 1.15 QALY, respectively. The ICER of 'PEG/RBV trial' compared with 'dual therapy' was $37 500/QALY. 'IL28B triage' and 'triple therapy' provided little benefit compared with 'PEG/RBV trial,' and both had ICERs exceeding $300 000/QALY. In sensitivity analyses, IFN-free treatment attaining 90% SVR had an ICER less than $100 000/QALY compared with 'PEG/RBV trial' when its cost was $109 000 or less (125% of the cost of PEG/RBV/TVR).

CONCLUSION

HCV protease inhibitors are most efficiently used in HIV/HCV coinfection after a trial of PEG/RBV, sparing protease inhibitors for those who attain rapid virologic response and SVR. The cost-effectiveness of IFN-free regimens for HIV/HCV coinfection will depend on the cost of these therapies.

Observer bias in randomized clinical trials with time-to-event outcomes: systematic review of trials with both blinded and non-blinded outcome assessors

BACKGROUND

We wanted to evaluate the impact of nonblinded outcome assessors on estimated treatment effects in time-to-event trials.

METHODS

Systematic review of randomized clinical trials with both blinded and nonblinded assessors of the same time-to-event outcome. Two authors agreed on inclusion of trials and outcomes. We compared hazard ratios based on nonblinded and blinded assessments. A ratio of hazard ratios (RHR)<1 indicated that nonblinded assessors generated more optimistic effect estimates. We pooled RHRs with inverse variance random-effects meta-analysis.

RESULTS

We included 18 trials. Eleven trials (1969 patients) with subjective outcomes provided hazard ratios, RHR 0.88 (0.69 to 1.12), (I2=44%, P=0.06), but unconditional pooling was problematic because of qualitative heterogeneity. Four atypical cytomegalovirus retinitis trials compared experimental oral administration with control intravenous administration of the same drug, resulting in bias favouring the control intervention, RHR 1.33 (0.98 to 1.82). Seven trials of cytomegalovirus retinitis, tibial fracture and multiple sclerosis compared experimental interventions with standard control interventions, e.g. placebo, no-treatment or active control, resulting in bias favouring the experimental intervention, RHR 0.73 (0.57 to 0.93), indicating an average exaggeration of nonblinded hazard ratios by 27% (7% to 43%).

CONCLUSIONS

Lack of blinded outcome assessors in randomized trials with subjective time-to-event outcomes causes high risk of observer bias. Nonblinded outcome assessors typically favour the experimental intervention, exaggerating the hazard ratio by an average of approximately 27%; but in special situations, nonblinded outcome assessors favour control interventions, inducing a comparable degree of observer bias in the reversed direction.

Valganciclovir for the prevention and treatment of cytomegalovirus disease in immunocompromised hosts

Valganciclovir (Valcyte, Roche), a prodrug of the deoxyguanosine analog ganciclovir (Cytovene, Roche), is indicated for induction and maintenance treatment of cytomegalovirus retinitis in patients with AIDS and for prevention of cytomegalovirus disease in selected high-risk solid organ transplant recipients. After oral administration, valganciclovir is rapidly absorbed and converted to ganciclovir by intestinal and hepatic esterases. Valganciclovir is a highly recognized substrate of the intestinal peptide transporter PEPT1, which underlies the tenfold higher bioavailability of ganciclovir after valganciclovir compared to oral ganciclovir administration. At oral dose of 900 mg, valganciclovir provides a systemic ganciclovir exposure that is comparable to intravenous ganciclovir, at the standard dose of 5 mg/kg of body weight. Subsequent phosphorylation of ganciclovir, which occurs preferentially within cytomegalovirus-infected cells, results in the active metabolite, ganciclovir triphosphate, which is responsible for suppressing viral DNA synthesis by competitively inhibiting the incorporation of the natural substrate deoxyguanosine into viral DNA and thereby, terminating cytomegalovirus replication.

Prevention of HIV-associated opportunistic infections and diseases in the age of highly active antiretroviral therapy

Since the introduction of highly active antiretroviral therapy (HAART), the rates of opportunistic infections have decreased markedly as has overall morbidity and mortality from HIV infection in developed countries. However, opportunistic infections remain the most important cause of death in HIV-infected people due to both late presentation of HIV infections and failure of HAART to adequately restore cell-mediated immunity in all individuals. While prophylaxis may be discontinued in patients who have responded to HAART with sustained increases of their CD4 counts above risk thresholds, for those patients who fail HAART, those who are unable to tolerate it, or whose treatments are interrupted, opportunistic-infection prophylaxis remains essential. Some HIV-associated diseases, such as anogenital human papilloma virus-induced neoplasia and hepatitis C infection, have not decreased in frequency with the advent of HAART. For these conditions, effective screening and treatment programs will be necessary to prevent ongoing morbidity. This review will provide an update on HIV-associated opportunistic infections and their prevention in the age of HAART, as well as discuss novel presentations of opportunistic illnesses, such as immune restoration syndromes.

Advances in the management of viral infections

Viral infections are common in cancer patients. The risk and severity of infection are influenced by patient, disease, treatment, and viral factors. Severe viral infections are more likely to occur in treatment regimens that are more immunosuppressive. Historically, the most frequent severe infections have been due to herpesviruses, but more recently, other pathogens, especially community respiratory and hepatitis viruses, have received increasing attention as major viral pathogens in cancer patients. Because of the new diagnostic assays and the introduction of better therapeutic options, knowledge of viral infections is important in optimizing antineoplastic therapies.

Assessment of Cytomegalovirus Hybrid Preventative Strategy in Pediatric Heart Transplant Patients

BACKGROUND

Prevention strategies for cytomegalovirus (CMV) in pediatric transplant recipients are sparsely reported. A hybrid strategy that combines prophylaxis with preemptive therapy using serial CMV viral load monitoring is an emerging option. We report our clinical outcomes with a hybrid strategy in pediatric heart transplant recipients.

METHODS

A retrospective chart review was performed for pediatric heart transplant recipients who received a hybrid strategy of 2-4 weeks intravenous ganciclovir followed by serial whole blood CMV monitoring from 2002 to 2010. Subject demographics, medications, drug levels, serial CMV viral loads, intravascular ultrasound and angiography reports, and histopathology were collected. Descriptive statistics and patient groups were compared using χ(2), Fisher's exact, and Wilcoxon rank-sum tests.

RESULTS

Twelve females and 13 males, ranging from 4 months to 19 years of age, underwent 26 heart transplants. Mean follow-up was 39 months (range, 5-94 months). Fourteen (54%) subjects were CMV donor (D) + /recipient (R) - , 8 (31%) were D + /R + , and 4 (15%) were D - /R + . Six subjects (23%) died of complications unrelated to CMV. Median prophylaxis duration was 25 days (range, 7-70 days). Ten (38%) subjects developed CMV infection: 1 subject had 2 episodes of CMV syndrome, and 1 subject had 2 episodes CMV. Although 6 of 14 patients with coronary artery vasculopathy had prior CMV, no association was found (P = .81). Median time to first CMV DNAemia was 2.3 months (range, 9 days to 24.8 months). Median time to viral load clearance was 29 days (range, 4-233 days). In addition, 25 D - /R- patients were transplanted and received no prophylaxis; 2 (8%) patients developed CMV infection.

CONCLUSIONS

Pediatric heart transplant recipients who were at risk for CMV and treated with a novel preventative hybrid strategy developed CMV infection, syndrome, and disease at rates similar to those reported in literature for prophylactic strategies.

Recent developments in the treatment of posterior uveitis

Uveitis is an intraocular inflammation that can be caused by infection, autoimmune disease, trauma or malignancy. It is a serious cause of visual handicap and therapy is targeted at: removal of possible infectious agents, the immunological processes that lead to or sustain the inflammation and finally to prevent or treat the destructive effects of the inflammation on the delicate ocular structures. In this review the latest developments concerning the treatment of posterior uveitis are illuminated, e. g., new approaches concerning the treatment of infectious uveitis including the therapy of herpes virus (VZV, HSV and CMV), bacterial and toxoplasma infections of the eye. Several new ways to influence the immune response and inflammation are described including the use of interferons, modulation of cytokines, soft steroids, other new immunosuppressive drugs and treatment of autoimmune uveitis by oral tolerization. An overview is given to illustrate new ways to administer drugs into eyes, such as intravitreal devices. Finally new developments in the field of the treatment of the various complications of uveitis (cystoid macular edema) are described.

The role of ganciclovir for the management of cytomegalovirus retinitis in HIV patients: Pharmacological review and update on new developments

OBJECTIVE

To review the pharmacology and pharmacokinetics of intravenous, oral and intraocular ganciclovir, and to discuss the role of these various formulations in the management of cytomegalovirus (CMV) retinitis in AIDS patients.

DATA SOURCES

A MEDLINE search (1987 through November 1995) of English-language literature using the main medical subject headings 'ganciclovir' and 'cytomegalovirus', and the subheading 'acquired immunodeficiency syndrome'. Relevant articles were also selected from references of identified articles. Abstracts from recent medical conferences of infectious diseases, pharmacology and human immunodeficiency virus were screened for additional data.

STUDY SELECTION AND DATA EXTRACTION

All articles and abstracts discussing the use of ganciclovir for the management or prophylaxis of CMV retinitis in AIDS patients were considered for inclusion. Pertinent information, as judged by the authors, was selected and synthesized for discussion.

DATA SYNTHESIS

Ganciclovir has demonstrated virustatic activity against CMV, and is often administered 5 mg/kg intravenously every 12 h as first-line therapy for CMV retinitis. Intravenous maintenance therapy at 5 mg/kg daily is usually effective at delaying retinitis progression for approximately 60 to 70 days. Neutropenia and thrombocytopenia are observed frequently, often necessitating interruption or discontinuation of therapy. Local drug administration may delay disease progression even further, and may be considered for patients who are intolerant to or failing intravenous therapy. However, systemic ganciclovir should be encouraged to reduce the risk of developing contralateral eye or end-organ CMV disease. Oral ganciclovir at 1 g tid is almost as effective as intravenous ganciclovir 5 mg/kg/day in delaying retinitis progression and is associated with fewer line-related complications. Absorption, drug interactions, cost and compliance should also be considered.

CONCLUSIONS

Until recently, ganciclovir was available only for intravenous use. Recent developments allow for intraocular and oral administration of this agent. A clear understanding of the advantages and disadvantages of these new formulations is required in order to select the most appropriate product for managing CMV retinitis in AIDS patients.

Genotyping cytomegalovirus UL97 mutations by high-resolution melting analysis with unlabeled probe

Human cytomegalovirus (CMV) is an opportunistic pathogen, and infections with this virus can be treated with ganciclovir (GCV). Most GCV-resistant clinical CMV isolates contain a mutation in the UL97 gene. Genotypic assays for diagnostic screening of GCV-resistant CMV have been developed. High-resolution melting analysis (HRMA) with unlabeled probe is considered a perfect tool for this purpose. In this study, we have developed an HRMA-based genotypic test for the detection of UL97 mutations. Wild type and M460V/I mutants of UL97 were constructed. HRMA with unlabeled probe was used as a genotyping method for the detection of M460V/I mutations. The melting peaks obtained directly from PCR products did not enable us to distinguish the wild type from M460 mutants. The sensitivity and accuracy of HRMA were dramatically improved by using unlabeled probe. HRMA with unlabeled probe successfully distinguished M460V from M460I and served well for the detection of M460V/I mutations in clinical samples. HRMA with unlabeled probe proves to be a sensitive and cost-effective genotyping method for the detection of M460 mutations.

Antiviral drugs for viruses other than human immunodeficiency virus

Most viral diseases, with the exception of those caused by human immunodeficiency virus, are self-limited illnesses that do not require specific antiviral therapy. The currently available antiviral drugs target 3 main groups of viruses: herpes, hepatitis, and influenza viruses. With the exception of the antisense molecule fomivirsen, all antiherpes drugs inhibit viral replication by serving as competitive substrates for viral DNA polymerase. Drugs for the treatment of influenza inhibit the ion channel M(2) protein or the enzyme neuraminidase. Combination therapy with Interferon-α and ribavirin remains the backbone treatment for chronic hepatitis C; the addition of serine protease inhibitors improves the treatment outcome of patients infected with hepatitis C virus genotype 1. Chronic hepatitis B can be treated with interferon or a combination of nucleos(t)ide analogues. Notably, almost all the nucleos(t) ide analogues for the treatment of chronic hepatitis B possess anti-human immunodeficiency virus properties, and they inhibit replication of hepatitis B virus by serving as competitive substrates for its DNA polymerase. Some antiviral drugs possess multiple potential clinical applications, such as ribavirin for the treatment of chronic hepatitis C and respiratory syncytial virus and cidofovir for the treatment of cytomegalovirus and other DNA viruses. Drug resistance is an emerging threat to the clinical utility of antiviral drugs. The major mechanisms for drug resistance are mutations in the viral DNA polymerase gene or in genes that encode for the viral kinases required for the activation of certain drugs such as acyclovir and ganciclovir. Widespread antiviral resistance has limited the clinical utility of M(2) inhibitors for the prevention and treatment of influenza infections. This article provides an overview of clinically available antiviral drugs for the primary care physician, with a special focus on pharmacology, clinical uses, and adverse effects.

Optimal management of cytomegalovirus retinitis in patients with AIDS

Cytomegalovirus (CMV) retinitis is the most common cause of vision loss in patients with acquired immunodeficiency syndrome (AIDS). CMV retinitis afflicted 25% to 42% of AIDS patients in the pre-highly active antiretroviral therapy (HAART) era, with most vision loss due to macula-involving retinitis or retinal detachment. The introduction of HAART significantly decreased the incidence and severity of CMV retinitis. Optimal treatment of CMV retinitis requires a thorough evaluation of the patient's immune status and an accurate classification of the retinal lesions. When retinitis is diagnosed, HAART therapy should be started or improved, and anti-CMV therapy with oral valganciclovir, intravenous ganciclovir, foscarnet, or cidofovir should be administered. Selected patients, especially those with zone 1 retinitis, may receive intravitreal drug injections or surgical implantation of a sustained-release ganciclovir reservoir. Effective anti-CMV therapy coupled with HAART significantly decreases the incidence of vision loss and improves patient survival. Immune recovery uveitis and retinal detachments are important causes of moderate to severe loss of vision. Compared with the early years of the AIDS epidemic, the treatment emphasis in the post- HAART era has changed from short-term control of retinitis to long-term preservation of vision. Developing countries face shortages of health care professionals and inadequate supplies of anti-CMV and anti-HIV medications. Intravitreal ganciclovir injections may be the most cost effective strategy to treat CMV retinitis in these areas.

[Treatment of opportunistic infections in adolescent and adult patients infected with the human immunodeficiency virus during the era of highly active antiretroviral therapy. AIDS Study Group (GESIDA) and National AIDS Plan Expert Committee]

Despite the huge advance that highly active antiretroviral therapy has represented for the prognosis of infection by human immunodeficiency virus (HIV), opportunistic infections continue to be a cause of morbidity and mortality in HIV-infected patients. This is often the case because of severe immunodepression, poor adherence to antiretroviral therapy, failure of therapy, or the fact that patients are unaware of their HIV-positive status and debut with an opportunistic infection. This article updates the guidelines on treatment of acute episodes of various opportunistic infections in HIV-infected patients, including infections due to parasites, fungi, viruses, mycobacteria, and bacteria. This edition has a new chapter on imported parasite infections as well as additional information on endemic mycoses in the chapter on fungal infections, taking into account the growing number of immigrants in our setting. Lastly, the chapter on the immune reconstitution syndrome has also been updated, providing relevant data on a phenomenon that has clinical and diagnostic repercussions in patients who start antiretroviral therapy while they are severely immunodepressed (English version available at http://www.gesida.seimc.org).

Modulation of Ganciclovir Intestinal Absorption in Presence of Absorption Enhancers

The purpose of this investigation was to study the influences of absorption enhancers in increasing oral bioavailability of Ganciclovir (GAN) by assessing the transepithelial permeation across cell monolayers in vitro and bioavailability in rats in vivo. The permeation of GAN across Caco-2 and MDCK cell monolayers in the absence/presence of dimethyl-beta-cyclodextrin (DMbetaCD), chitosan hydrochloride (CH), sodium lauryl sulphate (SLS), and their combinations was studied for a 2-h period. GAN was administered to rats in absence/presence of absorption enhancers and drug contents in plasma were estimated. We found that the apparent permeability coefficient (Papp) of GAN in absence of absorption enhancers (control) were 0.261 +/- 0.072 x 10(-6) and 0.486 +/- 0.063 x 10(-6) cm/s in Caco-2 and MDCK cell monolayers, respectively, whereas in the presence of DMbetaCD, CH, SLS, and their combinations, Papp of GAN increased by 5- to 25-fold and 7- to 33-fold as compared to control in Caco-2 and MDCK cell monolayers, respectively. However, in rats, the maximum enhancement in bioavailability of GAN during coadministration of these absorption enhancers was only fivefold compared to GAN control. To conclude, the absorption enhancers-DMbetaCD, CH, SLS, and their combinations demonstrated significant improvement in transepithelial permeation and bioavailability of GAN.

Oral valganciclovir as preemptive therapy for cytomegalovirus infection post allogeneic stem cell transplantation

Antiviral compounds including ganciclovir, foscarnet, and cidofovir are routinely used in the treatment of cytomegalovirus (CMV) infection and disease; however, these agents have a poor oral bioavailability and have the inconvenience and expense of intravenous administration.

AIM OF THE STUDY

To evaluate the safety and efficacy of oral valganciclovir (VGCV) for preemptive treatment of CMV reactivation in the setting of allogeneic hematopoietic stem cell transplantation (HSCT).

PATIENTS AND METHODS

We treated 15 patients receiving allogeneic HSCT from related (n=9) or unrelated (n=6) donors. In all patients, either the donor, host, or both were CMV Ig G positive pretransplant. Indication for therapy was preemptive treatment of CMV infection defined as one or two consecutive positive tests of pp65 antigenemia assay or CMV-polymerase chain reaction (PCR). VGCV was administered orally in a dosage of 900 mg b.i.d. for 2 weeks, followed by 450 mg b.i.d. for 2 additional weeks.

RESULTS

Patients developed a positive CMV-PCR after a median of 52 days (range 37-427) post HSCT and a positive pp65 antigenemia after a median time of 74 days (range 37-427) post HSCT. Preemptive treatment with VGCV was started a median time of 56 days (range 37-429) after transplant. In all, 11 patients (73%) completed the 28 days of therapy with VGCV. All patients showed a complete clearance of the virus. The median time to achieve a negative CMV-PCR was 6 days (range 4-18). A relapse of CMV infection after VGCV preemptive therapy occurred in 6 patients (40%). No patient developed early or late CMV disease. Six patients (40%) presented hematological toxicity including neutropenia and/or thrombocytopenia that required drug discontinuation in 4 cases.

CONCLUSION

VGCV administered as preemptive therapy for CMV infection in patients receiving an allogeneic HSCT showed promise for treating this frequent complication. Prospective randomized studies in this setting are mandatory to yield more definitive results.

Economic evaluation of treatment administration strategies of ganciclovir for cytomegalovirus retinitis in HIV/AIDS patients in Thailand: a simulation study

BACKGROUND

There are many effective interventions, via various routes (intravenous [IV], oral [OR], intravitreal injection [IVT] and intraocular implantation [IMP]), for treating cytomegalovirus retinitis (CMVR) that have become available. There are large variations in treating CMVR in clinical practice in Thailand.

OBJECTIVE

To evaluate the incremental cost-effectiveness ratio (ICER) of providing (i) IVT, (ii) IV/OR and (iii) IMP ganciclovir to patients with HIV/AIDS and CMVR versus providing no treatment.

DESIGN

A simulation study for which the input parameters were derived from a systematic review of the literature, a hospital-based survey and patient interviews.

SETTING

The analysis assumed a Thai healthcare system perspective. However, the model was run using both societal and healthcare provider perspectives.

RESULTS

Our results suggest that IVT ganciclovir was cost effective and the best option for treating patients with CMVR irrespective of whether patients received antiretroviral treatment (ART). In patients receiving ART, moving from IVT to IV/OR ganciclovir was also likely to be a cost-effective option. Offering IMP ganciclovir was not likely to be cost effective. Providing treatments for patients with bilateral CMVR was more cost effective than providing treatments for those with unilateral CMVR, and offering treatments for patients receiving ART was better value for money than treating patients without ART.

CONCLUSIONS

Our models suggest that IV/OR ganciclovir should be recommended for the treatment of unilateral and bilateral CMVR for patients receiving ART in the Thai healthcare system. IVT ganciclovir may also have a role in the treatment of CMVR patients not receiving ART.

HIV and other lentiviral infections cause defects in neutrophil chemotaxis, recruitment, and cell structure: immunorestorative effects of granulocyte-macrophage colony-stimulating factor

Patients with HIV infection exhibit deficits in bacterial and fungal clearance, and possibly depressed innate immunity. In this study, we observed that neutrophils from HIV-infected patients have a profound defect in chemotaxis in response to endogenous (IL-8) and bacterial (fMLP) chemoattractants, which was directly correlated with peripheral CD4(+) lymphocyte levels but not plasma viral load. A similar chemotactic defect was observed in the feline immunodeficiency virus (FIV) model of HIV infection. Intravital microscopy of FIV-infected animals revealed marked impairment in the in vivo recruitment of leukocytes; specifically integrin-dependent neutrophil adhesion and emigration induced by bacterial products. Treatment of FIV-infected animals with GM-CSF re-established both neutrophil recruitment (rolling, adhesion, and emigration) and in vitro chemotaxis to the levels seen in uninfected animals. This restoration of neutrophil responses was not due to GM-CSF-mediated priming. Rather, HIV and FIV infections resulted in defective neutrophil development, with an ensuing reduction in neutrophil granularity and chemotactic receptor expression. GM-CSF therapy restored neutrophil granularity, implying restoration of normal neutrophil development. Together, our findings underscore the fundamental defects in innate immunity caused by lentivirus infections, while also indicating that GM-CSF may be a potential immunorestorative therapy for HIV-infected patients.

Discovery of a novel series of inhibitors of human cytomegalovirus primase

Infection by human cytomegalovirus (hCMV) remains a potent threat to susceptible people throughout the world. We have discovered a series of imidazolyl-pyrimidine compounds, which were found to be irreversible inhibitors of the hCMV UL70 primase based on results from radiolabeling and SAR studies. Two promising analogs are described that rival ganciclovir and cidofovir in antiviral potency and possess improved cytotoxicity profiles.

Ganciclovir implant in the treatment of cytomegalovirus retinitis

The ganciclovir implant is a sustained-release intraocular drug delivery system used to treat cytomegalovirus retinitis that provides a high and steady-state concentration of the drug in the vitreous cavity over a period of 7-8 months. Randomized, controlled clinical trials have demonstrated a superior efficacy of the implant compared with intravenous ganciclovir. Severe adverse events associated with the implant are uncommon, though potentially blinding. In addition, the implant provides no protection against second-eye or visceral cytomegalovirus retinitis infections. This review summarizes the clinical indications for and complications associated with the ganciclovir implant.

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.

Therapy of other viral infections: herpes to hepatitis

Over the past several years, there has been an increase in knowledge pertaining to the diagnosis and management strategies for the herpes family (Types 1-8), the pox viruses, mumps, measles, rubella, and parvovirus B19 as well as the viral etiologies of hepatitis. Various antiviral treatments, such as nucleoside analogs and interferon therapy, have been available to reduce the signs and symptoms of these common viral infections. This article summarizes the preferred treatment strategies to be employed for each of the viruses for reducing severity, duration, recurrences (notably in the herpes family), transmission rates, as well as preventive alternatives. The majority of the therapeutic options attenuate the course of disease. Treatment decisions are driven by knowledge of the natural history and often are tailored to incorporate clinical circumstances for individual patients. Promotion of community awareness and the development of vaccines should be emphasized in the battle against these common viruses, particularly the herpes simplex viruses, the pox viruses, and hepatitis B.

Canadian consensus guidelines for the management of cytomegalovirus disease in HIV/AIDS

BACKGROUND

The management of HIV-infected patients with cytomegalovirus (CMV) disease has changed significantly with the availability of highly active antiretroviral therapy (HAART).

OBJECTIVES

These updated guidelines are intended to provide practical help to physicians managing HIV-positive patients with or at risk for CMV disease.

METHODS

The 10 members of the Canadian CMV Disease in HIV/AIDS Consensus Group were infectious disease specialists, a primary care physician and ophthalmologists with expertise in HIV and CMV infection. Financial support by Hoffmann-La Roche Canada Ltd was unrestricted, and was limited to travel expenses and honoraria. The consensus group met in June and October 2002. Key areas to be considered were identified, and group members selected, reviewed and presented relevant recent literature for their assigned section for the group's consideration. Evidence was assessed based on established criteria, which were expert opinions of the members. Draft documents were circulated to the entire group and modified until consensus was reached. The final guidelines represent the group's consensus agreement. The guidelines were approved by the Canadian Infectious Disease Society.

RESULTS AND CONCLUSIONS

The guidelines address symptom monitoring, screening for early detection and prevention, and treatment using oral, intravenous and intraocular anti-CMV therapies in conjunction with HAART.

Complications of ganciclovir implant surgery in patients with cytomegalovirus retinitis: the Ganciclovir Cidofovir Cytomegalovirus Retinitis Trial

PURPOSE

To describe the complications of ganciclovir implant surgery in patients with cytomegalovirus retinitis.

METHODS

Prospective data collection within the context of a randomized, controlled clinical trial, comparing a regimen of the ganciclovir implant plus oral ganciclovir to one of intravenous cidofovir for the treatment of cytomegalovirus retinitis in patients with AIDS. Adverse events were compared for patients undergoing implant surgery in the following groups: primary versus replacement implant surgery, inpatient versus outpatient surgery, and general versus local anesthesia.

RESULTS

Fifty-six eyes of 42 patients underwent a total of 74 ganciclovir implant surgeries. Vitreous hemorrhage was the most common adverse event, occurring in 10% of eyes undergoing surgery with local anesthesia but in no eyes undergoing surgery with general anesthesia. All vitreous hemorrhages resolved within 60 days. Patients in the general anesthesia and inpatient surgery groups tended to have a lower risk of complications in the first 30 days than did patients in the local anesthesia and outpatient surgery groups, but no differences in the complication rate were found after 60 days. Visual acuity was similar among these different groups. There were no cases of endophthalmitis.

CONCLUSION

Ganciclovir implant surgery in patients with AIDS and cytomegalovirus retinitis was associated with a low risk of serious complications in the first 60 days after surgery. Vitreous hemorrhage was the most commonly observed complication and resolved in all cases.

Prevention of opportunistic infections in adult and adolescent patients with HIV infection. GESIDA/National AIDS Plan guidelines, 2004 [correction]

OBJECTIVE

To provide an update of guidelines from the Spanish AIDS Study Group (GESIDA) and the National AIDS Plan (PNS) committee on the prevention of opportunistic infections in adult and adolescent HIV-infected patients.

METHODS

These consensus recommendations have been produced by a group of experts from GESIDA and/or the PNS after reviewing the earlier document and the scientific advances in this field in the last years. The system used by the Infectious Diseases Society of America and the United States Public Health Service has been used to classify the strength and quality of the data.

RESULTS

This document provides a detailed review of the measures for the prevention of infections caused by viruses, bacteria, fungi and parasites in the context of HIV infection. Recommendations are given for preventing exposure and for primary and secondary prophylaxis for each group of pathogens. In addition, criteria are established for the withdrawal of prophylaxis in patients who respond well to highly active antiretroviral therapy (HAART).

CONCLUSIONS

HAART is the best strategy for the prevention of opportunistic infections in HIV-positive patients. Nevertheless, prophylaxis is still necessary in countries with limited economic resources, in highly immunodepressed patients until HAART achieves beneficial effects, in patients who refuse to take or who cannot take HAART, in those in whom HAART is not effective, and in the small group of infected patients with inadequate recovery of CD4+ T lymphocyte counts despite good inhibition of HIV replication.

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.

Cytomegalovirus Disease in the Highly Active Antiretroviral Therapy Era

Cytomegalovirus (CMV) is a major cause of morbidity and mortality in AIDS patients. Epidemiologic studies indicate that until 10 years ago, nearly one half of HIV-infected patients eventually developed CMV end-organ disease, including chorioretinitis, esophagitis, colitis, pneumonia, and central nervous system disease. Since the introduction of highly active antiretroviral therapy (HAART) this incidence has declined dramatically. Nonetheless, patients still present with CMV disease and resistance or intolerance to HAART does develop, which may give rise to a resurgence of CMV syndromes in AIDS patients. Until recently, only intravenous ganciclovir and foscarnet were available for management of CMV infection. With the advent of additional agents, clinicians now face the challenge of optimizing therapy for individual patients. This paper reviews the most common clinical syndromes caused by CMV, the treatment options, as well as an approach to diagnosing and treating antiviral resistance.

The human cytomegalovirus

Human cytomegalovirus (HCMV), a betaherpesvirus, represents the major infectious cause of birth defects, as well as an important pathogen for immunocompromised individuals. The viral nucleocapsid containing a linear double-stranded DNA of 230 kb is surrounded by a proteinaceous tegument, which is itself enclosed by a loosely applied lipid bilayer. Expression of the HCMV genome is controlled by a cascade of transcriptional events that leads to the synthesis of three categories of viral proteins designated as immediate-early, early, and late. Clinical manifestations can be seen following primary infection, reinfection, or reactivation. About 10% of infants are infected by the age of 6 months following transmission from their mothers via the placenta, during delivery, or by breastfeeding. HCMV is a significant post-allograft pathogen and contributes to graft loss independently from graft rejection. Histopathologic examination of necropsy tissues demonstrates that the virus enters via the epithelium of the upper alimentary, respiratory, or genitourinary tracts. Hematogenous spreading is typically followed by infection of ductal epithelial cells. Infections are kept under control by the immune system. However, total HCMV clearance is rarely achieved, and the viral genome remains at selected sites in a latent state. Virological and molecular detection of HCMV, as well as serological demonstration of a specific immune response, are used for diagnosis. Treatment of HCMV infections is difficult because there are few options. The presently available drugs produced a significant clinical improvement, but suffer from poor oral bioavailability, low potency, development of resistance in clinical practice, and dose-limiting toxicities.

Preclinical and toxicology studies of 1263W94, a potent and selective inhibitor of human cytomegalovirus replication

1263W94 is a novel benzimidazole compound being developed for treatment of human cytomegalovirus infection. No adverse pharmacological effects were demonstrated in safety pharmacology studies with 1263W94. The minimal-effect dose in a 1-month rat study was 100 mg/kg/day, and the no-effect dose in a 1-month monkey study was 180 mg/kg/day. Toxic effects were limited to increases in liver weights, neutrophils, and monocytes at higher doses in female rats. 1263W94 was not genotoxic in the Ames or micronucleus assays. In the mouse lymphoma assay, 1263W94 was mutagenic in the absence of the rat liver S-9 metabolic activation system, with equivocal results in the presence of the S-9 mix. Mean oral bioavailability of 1263W94 was >90% in rats and approximately 50% in monkeys. Clearance in rats and monkeys was primarily by biliary secretion, with evidence of enterohepatic recirculation. In 1-month studies in rats and monkeys, mean peak concentrations and exposures to 1263W94 increased in near proportion to dose. Metabolism of 1263W94 to its primary metabolite, an N-dealkylated analog, appeared to be mediated via the isozyme CYP3A4 in humans. 1263W94 was primarily distributed in the gastrointestinal tract of rats but did not cross the blood-brain barrier. In monkeys, 1263W94 levels in the brain, cerebrospinal fluid, and vitreous humor ranged from 4 to 20%, 1 to 2%, and <1%, of corresponding concentrations in plasma, respectively. The high level of binding by 1263W94 to human plasma proteins (primarily albumin) was readily reversible, with less protein binding seen in the monkey, rat, and mouse. Results of these studies demonstrate a favorable safety profile for 1263W94.

A safety study of oral valganciclovir maintenance treatment of cytomegalovirus retinitis

Valganciclovir, an oral prodrug of the anti-cytomegalovirus (CMV) agent ganciclovir, was evaluated in a single-arm open-label safety study. AIDS patients (median CD4 lymphocyte count of 140 cells/microL) with treated CMV retinitis (N = 212) received 900-mg once-daily valganciclovir maintenance therapy with courses of 900-mg twice-daily valganciclovir induction therapy as needed to treat progression. After a median treatment duration of 372 days, the adverse event profile was similar to that reported for intravenous (IV) and oral ganciclovir. Adverse event rates of note were diarrhea (35%), nausea (23%), fever (18%), neutropenia (absolute neutrophil count <500 cells/microL) (10%), and anemia (hemoglobin <8.0 g/dL) (12%). Consistent with prior treatment studies of oral ganciclovir, IV catheter-related adverse events were uncommon (6%) and lower than previously reported for IV ganciclovir. The mortality rate was 0.072 deaths per patient-year. Progression of CMV retinitis occurred in 17% of patients during the study treatment period, usually in association with a low CD4 cell count. Other than a higher than expected frequency of oral candidiasis (17%), no clinical toxicities or laboratory abnormalities occurred during treatment with valganciclovir that have not been observed during treatment with ganciclovir.

Cytomegalovirus retinitis after initiation of highly active antiretroviral therapy in HIV infected patients: natural history and clinical predictors

PURPOSE

To characterize the natural course and clinical predictors of cytomegalovirus (CMV) retinitis in human immunodeficiency virus (HIV)-infected patients after initiation of highly active antiretroviral therapy (HAART).

METHODS

Retrospective analysis of 53 HIV-positive patients (73 eyes with CMV retinitis) treated with and without HAART. All participants continued to take anti-CMV therapy. Survival analysis was used to characterize the natural course of CMV retinitis. Proportional hazards analysis was performed to assess the correlation of the nine potential clinical predictors (baseline CD4 count, post-HAART CD4 count, post-HAART rise in CD4 count, baseline weight, post-HAART rise in weight, post-HAART percentage rise in weight, log of baseline HIV viral load, log of minimum post-HAART HIV viral load, and post-HAART log unit reduction in HIV viral load) with the duration of CMV retinitis remission.

RESULTS

Patients receiving HAART had a median CMV retinitis remission duration of 574 days (95% confidence interval, 336-NA) whereas those not receiving HAART had a median remission duration of 80.5 days (95% confidence interval, 28-NA; P < 0.001). Within the HAART-treated population, the minimal viral load reached after HAART was the only clinical predictor to demonstrate significance (P = 0.0075). Several other clinical predictors demonstrated borderline significance; however, this was most likely due to the high correlation of these variables with the minimum post-HAART viral load. A potential secondary clinical predictor identified was the post-HAART rise in CD4 count (P = 0.085).

CONCLUSION

With the introduction of HAART, HIV-infected patients have much longer remission durations from recurrent CMV retinitis. The minimum HIV viral load level reached after the initiation of HAART treatment appears to be more important than other clinical variables in the prediction of favorable CMV retinitis remission status. Furthermore, a rise in CD4 T-lymphocyte count by itself appears to be a less significant clinical predictor but may be useful in combination with the HIV viral load data. Selective discontinuation of anti-CMV therapy may be considered in patients with a favorable set of clinical predictors.

A controlled trial of valganciclovir as induction therapy for cytomegalovirus retinitis

BACKGROUND

Valganciclovir is an orally administered prodrug that is rapidly hydrolyzed to ganciclovir. We compared the effects of oral valganciclovir with those of intravenous ganciclovir as induction therapy for newly diagnosed cytomegalovirus retinitis in 160 patients with the acquired immunodeficiency syndrome (AIDS).

METHODS

The primary end point was photographically determined progression of cytomegalovirus retinitis within four weeks after the initiation of treatment. Secondary end points included the achievement of a prospectively defined satisfactory response to induction therapy and the time to progression of cytomegalovirus retinitis. After four weeks, all patients received valganciclovir as maintenance therapy.

RESULTS

Eighty patients were randomly assigned to each treatment group. Of the patients who could be evaluated, 7 of 70 assigned to intravenous ganciclovir (10.0 percent) and 7 of 71 assigned to oral valganciclovir (9.9 percent) had progression of cytomegalovirus retinitis during the first four weeks (difference in proportions, 0.1 percentage point; 95 percent confidence interval, -9.7 to 10.0). Forty-seven of 61 patients (77.0 percent) assigned to intravenous ganciclovir and 46 of 64 (71.9 percent) assigned to valganciclovir had a satisfactory response to induction therapy (difference in proportions, 5.2 percentage points; 95 percent confidence interval, -20.4 to 10.1). The median times to progression of retinitis were 125 days in the group assigned to intravenous ganciclovir and 160 days in the group assigned to oral valganciclovir. The mean values for the area under the curve for the ganciclovir dosage interval were similar at both induction doses and maintenance doses. The frequency and severity of adverse events were similar in the two treatment groups.

CONCLUSIONS

Orally administered valganciclovir appears to be as effective as intravenous ganciclovir for induction treatment and is convenient and effective for the long-term management of cytomegalovirus retinitis in patients with AIDS.

Cytomegalovirus infections

Over the past two decades, there has been an escalation in the number of patients undergoing immunosuppressive therapy following solid organ or bone marrow transplantation, as well as a dramatic increase in the incidence of AIDS. As a result, human cytomegalovirus (HCMV)--once considered a neonatal disease--has captured great interest and importance as a major pathogen in both immunocompromised and immunocompetent patients. Like other members of herpesviridae family, HCMV establishes latency in myeloid lineage cells with potential for reactivation. The natural history of HCMV infection can be divided into primary infection, latency, and reinfection. This review article briefly discusses the molecular pathogenesis of HCMV, then focuses on the clinical picture of this disease, with emphasis on the skin pathology. Diagnostic methods and treatments are also discussed.

High dose oral ganciclovir treatment for cytomegalovirus retinitis

BACKGROUND

The oral formulation of ganciclovir is approved at a dose of 3.0 g/day for maintenance treatment of cytomegalovirus (CMV) retinitis following an initial induction course of intravenous (IV) anti-CMV therapy. Median time to progression of CMV retinitis is 12-20 days shorter with oral compared to IV ganciclovir maintenance, likely due to the limited oral bioavailability of ganciclovir.

OBJECTIVES

We hypothesized that higher systemic drug exposures associated with increased doses of oral ganciclovir would be associated with increased efficacy.

STUDY DESIGN

Maintenance treatment of CMV retinitis with higher than standard doses of oral ganciclovir (>3.0 g/day) was studied in 281 AIDS patients with previously treated, stable retinitis randomized to 3.0, 4.5 or 6.0 g/day oral, or 5 m/kg/day IV ganciclovir. Graders unaware of treatment assignments determined retinitis progression using fundus photographs. Vision, other ophthalmic measures and safety were assessed open-label.

RESULTS

Median days to photographic progression were 41, 50, 57 and 70, respectively (P=0.052; 3.0 g vs. IV). Hazard ratios for progression relative to IV were 1.66, 1.28 and 1.19 (P=0.016 for 3.0 g). NONMEM-modeled estimates of average serum ganciclovir concentration area under the curve (AUC(0-24)) correlated best with time to progression (P=0.0019). Six grams per day oral ganciclovir was most similar in efficacy to IV, although broad confidence intervals prevented a conclusive comparison. Patients receiving oral ganciclovir had a lower frequency of sepsis and IV catheter events.

CONCLUSIONS

This study suggests that the efficacy of ganciclovir for the maintenance treatment of CMV retinitis improves with increasing total drug exposure (measured as average serum concentration AUC(0-24)). All four regimens of ganciclovir were reasonably well tolerated, with safety profiles similar to what has been reported in prior work.