ME-609: A Treatment for Recurrent Herpes Simplex Virus Infections

COMPARATIVE EFFICACY OF ANTIVIRAL AGENTS FOR PREVENTION AND MANAGEMENT OF HERPES LABIALIS: A SYSTEMATIC REVIEW AND NETWORK META-ANALYSIS

OBJECTIVE

To compare the relative efficacy and safety of antiviral agents used in the prevention and management of herpes labialis through a network meta-analysis of clinical trials.

METHODS

A systematic search was performed in Ovid Medline PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus and Clinicaltrials.gov for randomized controlled trials (RCTs) reporting a comparison of antiviral agents in the management and prevention of herpes labialis in healthy/immunocompetent adults. The data extracted from the selected RCTs were assessed and a network meta-analysis (NMA) was performed. The interventions were ranked according to the surface under the cumulative ranking (SUCRA).

RESULTS

A total of 52 articles were included for qualitative synthesis and for the quantitative part, 26 articles were analyzed for the primary treatment outcome and 7 studies were analyzed for the primary prevention outcome. The combination therapy of oral valacyclovir and topical clobetasol was the best ranked with a mean reduction in healing time of -3.50 (95% CI -5.22 to -1.78) followed by vidarabine monophosphate of -3.22 (95% CI -4.59 to -1.85). No significant inconsistencies, heterogeneity, and publication bias were reported for TTH outcome analysis. For primary prevention outcomes, only 7 RCTs fulfilled the inclusion criteria, and none of the interventions was shown to be superior to each other. The absence of adverse events was reported by 16 studies, whereas other studies reported mild side effects only.

CONCLUSION

NMA highlighted that several agents were effective in the management of herpes labialis among which the combination of oral valacyclovir with topical clobetasol therapy was the most effective in reducing the time to heal. However, further studies are required to determine which intervention is the most effective in preventing the recurrence of herpes labialis.

Efficacy of Topical 5% Acyclovir-1% Hydrocortisone Cream (ME-609) for Treatment of Herpes Labialis: a systematic review

We performed a systematic review with the objective of verifying the efficacy of topical use 5% Acyclovir-1% Hydrocortisone cream compared to the placebo group for herpes simplex labialis treatment. We performed a literature search using MEDLINE, Embase, BIOSIS, LILACS, Scopus, Grey literature, the Cochrane Central Register of Controlled Trials, the ISI Web of Science and IBECS from 1990 to June 2014. We reported the outcomes using relative risk (RR) with 95% confidence intervals. The literature search yielded 180 potentially relevant publications. Reviews of the reference lists yielded two further citations. Among these papers, two were considered eligible for inclusion in this review. Both trials included 1,213 patients. A meta-analysis of these studies showed a RR = 0.77, (95% CI 0.70-0.86; p<0.001).This result suggests that an early episodic treatment with the combination of an antiviral and a steroid is beneficial for herpes simplex labialis treatment.

Effectiveness of topical corticosteroids in addition to antiviral therapy in the management of recurrent herpes labialis: a systematic review and meta-analysis

BACKGROUND

Recurrent herpes labialis (RHL) is one of the most common viral infections worldwide. The available treatments have limited efficacy in preventing the recurrence of ulcerative lesions and reducing the duration of illness. The objective of this review was to identify the effectiveness of topical corticosteroids in addition to antiviral therapy in the treatment of RHL infection.

METHODS

A systematic review of randomized clinical trials comparing the efficacy of combined therapy (topical corticosteroids with antiviral) with placebo or antiviral alone in the management of RHL was conducted. MEDLINE, EMBASE, CINAHL, Web of Science, the Cochrane library, and Google Scholar databases were searched. We used RevMan software to conduct the meta-analysis. A fixed-effects model was used for mild to moderate heterogeneity, whereas a random-effects model was used for significant heterogeneity. Heterogeneity among trials was established using I(2) and chi-square test for heterogeneity.

RESULTS

Four studies that fulfilled the selection criteria were included in this review. The total number of participants across included studies was 1,891 (range, 29 to 1,443). The antiviral drugs used were acyclovir, famciclovir, and valacyclovir. Corticosteroids used were 1% hydrocortisone and 0.05% fluocinonide. Pooled results showed that patients receiving combined therapy had a significantly lower recurrence rate of ulcerative lesions compared to those in both the placebo group (OR, 0.50; 95% CI, 0.39-0.66; P < .001) and the antiviral treatment alone group (OR, 0.73, 95% CI, 0.58-0.92; P = .007). The healing time was also significantly shorter in combined therapy in comparison to placebo (P < .001). However, there were no significant differences in healing time between combined therapy and antiviral alone. The adverse reactions in combined therapy were not significantly different than the placebo group (OR, 1.09; 95% C, 0.75-1.59; P = .85).

CONCLUSION

Treatment with combined therapy is safe and more effective than placebo or antiviral alone for preventing the recurrence of ulcerative lesions in RHL infection.

Novel composite efficacy measure to demonstrate the rationale and efficacy of combination antiviral-anti-inflammatory treatment for recurrent herpes simplex labialis

Historically, the primary target for research and treatment of recurrent herpes simplex labialis (HSL) has been limited to inhibiting herpes simplex virus (HSV) replication. Antiviral monotherapy, however, has proven only marginally effective in curtailing the duration and severity of recurrent lesions. Recently, the role of inflammation in the progression and resolution of recurrences has been identified as an additional target. This was evaluated in a randomized study comparing combination topical 5% acyclovir-1% hydrocortisone cream (AHC) with 5% acyclovir alone (AC; in the AHC vehicle) and the vehicle. The efficacy of each topical therapy was evaluated for cumulative lesion size--a novel composite efficacy endpoint incorporating episode duration, lesion area, and proportion of nonulcerative lesions. In that study, cumulative lesion area was significantly decreased with AHC compared with AC (25% decrease; P<0.05) and the vehicle (50% decrease; P<0.0001). As research continues in this arena, cumulative lesion area should be included as a measure of efficacy in clinical trials of recurrent HSL therapies.

Recent developments in anti-herpesvirus drugs

Background Herpesviruses notably establish lifelong infections, with latency and reactivation. Many of the known human herpesviruses infect large proportions of the population worldwide. Treatment or prevention of herpes infections and recurrent disease still pose a challenge in the 21st century. Sources of data Original papers and review articles, meeting abstracts, a book (Clinical Virology; DD Richman, RJ Whitley & FG Hayden eds) and company web sites. Areas of agreement For herpes simplex types 1 and 2 and for varicella zoster, acyclovir (ACV; now increasingly replaced by its prodrug valacyclovir, VACV) and famciclovir (FCV) have greatly reduced the burden of disease and have established a remarkable safety record. Drug-resistance, in the otherwise healthy population, has remained below 0.5% after more that 20 years of antiviral use. In immunocompromised patients, drug resistance is more common and alternative drugs with good safety profiles are desirable. For human cytomegalovirus disease, which occurs in immunocompromised patients, ganciclovir and increasingly its prodrug valganciclovir are the drugs of choice. However, alternative drugs, with better safety, are much needed. Areas of controversy Various questions are highlighted. Should the new 1-day therapies for recurrent herpes labialis and genital herpes replace the current standard multi-day therapies? The marked differences between VACV and FCV (e.g. triphosphate stability, effect on latency) may not yet be fully exploited? Do current antivirals reduce post-herpetic neuralgia (PHN)? For immunocompromised patients with varicella zoster virus (VZV) disease, should the first-line treatment be FCV, not ACV or VACV? Should there be more support to explore new avenues for current antivirals, for example in possibly reducing herpes latency or Alzheimer's disease (AD)? Should primary Epstein-Barr virus (EBV) disease in adolescents be treated with antivirals? How can new compounds be progressed when the perceived market need is small but the medical need is great. FCV was reclassified from prescription-only to pharmacist-controlled for herpes labialis in New Zealand in 2010; should this be repeated more widely? This article reviews new drugs in clinical trials and highlights some of the problems hindering their progress.

The helicase-primase complex as a target for effective herpesvirus antivirals

Herpes simplex virus and varicella-zoster virus have been treated for more that half a century using nucleoside analogues. However, there is still an unmet clinical need for improved herpes antivirals. The successful compounds, acyclovir; penciclovir and their orally bioavailable prodrugs valaciclovir and famciclovir, ultimately block virus replication by inhibiting virus-specific DNA-polymerase. The helicase-primase (HP) complex offers a distinctly different target for specific inhibition of virus DNA synthesis. This review describes the synthetic programmes that have already led to two HP-inhibitors (HPI) that have commenced clinical trials in man. One of these (known as AIC 316) continues in clinical development to date. The specificity of HPI is reflected by the ability to select drug-resistant mutants. The role of HP-antiviral resistance will be considered and how the study of cross--resistance among mutants already shows subtle differences between compounds in this respect. The impact of resistance on the drug development in the clinic will also be considered. Finally, herpesvirus latency remains as the most important barrier to a therapeutic cure. Whether or not helicase primase inhibitors alone or in combination with nucleoside analogues can impact on this elusive goal remains to be seen.

Safety and tolerability of combination acyclovir 5% and hydrocortisone 1% cream in adolescents with recurrent herpes simplex labialis

A Phase 3, open-label, multicenter study was conducted to assess the safety of the combination of 5% acyclovir and 1% hydrocortisone cream (AHC cream) in the treatment of recurrent herpes simplex labialis (HSL) in immunocompetent adolescents. Eligible subjects were aged 12 to 17 years and had a history of recurrent labial herpes with two or more episodes during the last 12 months. Subjects initiated treatment at the first signs or symptoms of a herpes recurrence-at the earliest prodromal phase and preferably before the presence of papules or vesicles. Subjects applied the cream topically five times per day for 5 days. Adverse events, categorization of recurrence (ulcerative or nonulcerative), and maximum lesion area (maximum area of an ulcerative lesion) were assessed. Of the 134 subjects analyzed for safety, 131 had data for categorization of recurrence at the post-treatment visit 3 ± 1 weeks after the last dose. Seventy-eight subjects (59.5%) had nonulcerative recurrences, and 53 (40.5%) had ulcerative recurrences. All 131 subjects reached the stage of normal skin, with no signs or symptoms, at the follow-up visit. The mean maximum lesion area in the 53 subjects with ulcerative herpes lesion was 39 mm(2). Five subjects reported five adverse events (secondary herpes labialis recurrences, n = 2; infectious rhinitis, n = 1; application site inflammation, n = 1; bronchial asthma, n = 1). All adverse events were of mild to moderate intensity. The results of this study demonstrate that the combination of AHC cream is well tolerated in the treatment of recurrent HSL in adolescents.

Herpes simplex virus helicase-primase inhibitors: recent findings from the study of drug resistance mutations

After several decades during which nucleoside analogues (especially acyclovir and penciclovir and their prodrugs) have benefited many patients suffering from herpes simplex virus (HSV) infections, the discovery of the helicase-primase inhibitors (HPIs) represents an interesting new approach. Although antiviral resistance has not been a major problem for nucleoside analogues in immunocompetent patients, the problem of acyclovir resistance in immunocompromised patients is well documented. Several HPIs are extremely potent antiviral compounds and may, therefore, offer an important alternative therapy in these patients. The potential for synergy, not just for the inhibition of virus replication but also to delay the appearance of drug-resistant virus, needs to be thoroughly investigated. The study of resistance to HPIs has been important towards understanding the mechanism of action of these compounds and confirming the target function. However, during the course of our studies on HPI resistance, we have made a number of interesting observations that may be relevant to their clinical use. This article draws attention to the major observations on HPI resistance reported by others and to our own recently published observations that have extended this expanding area of antiviral research.

Agents and strategies in development for improved management of herpes simplex virus infection and disease

The quiet pandemic of herpes simplex virus (HSV) infections has plagued humanity since ancient times, causing mucocutaneous infection such as herpes labialis and herpes genitalis. Disease symptoms often interfere with every-day activities and occasionally HSV infections are the cause of life-threatening or sight-impairing disease, especially in neonates and the immuno-compromised patient population. After infection the virus persists for life in neurons of the host in a latent form, periodically reactivating and often resulting in significant psychosocial distress for the patient. Currently no cure is available. So far, vaccines, ILs, IFNs, therapeutic proteins, antibodies, immunomodulators and small-molecule drugs with specific or non-specific modes of action lacked either efficacy or the required safety profile to replace the nucleosidic drugs acyclovir, valacyclovir, penciclovir and famciclovir as the first choice of treatment. The recently discovered inhibitors of the HSV helicase-primase are the most potent development candidates today. These antiviral agents act by a novel mechanism of action and display low resistance rates in vitro and superior efficacy in animal models. This review summarises the current therapeutic options, discusses the potential of preclinical or investigational drugs and provides an up-to-date interpretation of the challenge to establish novel treatments for herpes simplex disease.

Achievements and challenges in antiviral drug discovery

The last 40 years have seen the development of several antiviral drugs with therapeutic value in treating life-threatening or debilitating diseases such as those caused by HIV, hepatitis B virus, herpesviruses (such as herpes simplex virus and varicella zoster virus) and influenza virus. These relatively recent advances have been due to technical breakthroughs in the cultivation of viruses in the laboratory, identification of viral enzymes and, more recently, their molecular biology. We describe here the antecedence of several of the existing antivirals and their strengths and weaknesses. We indicate where the major challenges lie for future improvements of current therapies and possible new indications, such as hepatitis C virus and papillomavirus. We also describe how current antiviral therapies are restricted to a rather limited number of viral diseases of sufficient interest to the pharmaceutical industry. Finally we describe the potential threat of emerging viruses and bio-weapons and the challenges that they present to therapy.