oxadiazoles and Herpes-Genitalis

Acyclovir, valacyclovir, and famciclovir are used for the treatment of herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections. Helicase-primase inhibitors (HPIs) inhibit replication fork progression that separates double DNA strands into two single strands during DNA synthesis. The HPIs amenamevir and pritelivir have novel mechanisms of anti-herpetic action, and their once-daily administration has clinical efficacy for genital herpes. Among HPIs, amenamevir has anti-VZV activity. The concentrations of HSV-1 and VZV required for the 50% plaque reduction of amenamevir were 0.036 and 0.047 μM, respectively. We characterized the features of amenamevir regarding its mechanism, resistance, and synergism with acyclovir. Its antiviral activity was not influenced by the viral replication cycle, in contrast to acyclovir. A clinical trial of amenamevir for herpes zoster demonstrated its non-inferiority to valacyclovir. To date, amenamevir has been successfully used in over 1,240,000 patients with herpes zoster in Japan. Post-marketing surveillance of amenamevir in Japan reported side effects with significant potential risk identified by the Japanese Risk Management Plan, including thrombocytopenia, gingival bleeding, and palpitations, although none of these were serious. The clinical efficacy and safety profiles of amenamevir were established in patients with herpes zoster. Therefore, amenamevir as an HPI opens a new era of anti-herpes therapy.

Topics: Animals; Antiviral Agents; Clinical Trials as Topic; DNA Helicases; DNA Primase; Herpes Genitalis; Herpes Zoster; Herpesvirus 1, Human; Humans; Mice; Oxadiazoles

Herpes simplex virus (HSV) types 1 and 2 can cause infections with clinical manifestations ranging from benign and generally self-limiting blisters or sores as seen in labial and genital herpes through to severe and in rare cases even life-threatening infections. At present, approved treatments for herpes simplex virus are almost all nucleoside analogs. Novel antiviral approaches include therapeutic vaccines, with the most advanced having successfully completed Phase 2 clinical development. Moreover, several small molecules approaches are being developed for the treatment of genital or labial HSV infections. Of particular interest are two novel compounds (amenamevir and pritelivir) belonging to the new class of helicase-primase inhibitors with promising Phase 2 data.

Topics: Acyclovir; Antiviral Agents; Clinical Trials, Phase II as Topic; DNA Helicases; DNA Primase; Drug Resistance, Viral; Herpes Genitalis; Herpes Simplex; Herpes Simplex Virus Vaccines; Herpesvirus 1, Human; Herpesvirus 2, Human; Humans; Oxadiazoles; Pyridines; Sulfonamides; Thiazoles; Viral Proteins

Amenamevir is the international non-proprietary name for ASP2151 synthesized by Astellas Pharma, Inc. It is a structurally novel class of helicase-primase inhibitor and demonstrated more potency in vitro anti-viral activity with low cytotoxicity against varicella-zoster virus (VZV), herpes simplex virus type 1 (HSV-1), and herpes simplex virus type 2 (HSV-2) than acyclovir (ACV). Phase II randomized trial assessed the safety and efficacy of ASP2151 for episodic therapy of recurrent genital herpes was conducted. Participants self-initiated with ASP2151 (100, 200, or 400 mg daily for 3 days), ASP2151 (1,200 mg as a single dose), placebo for 3 days, or Valacyclovir (500 mg twice daily for 3 days). We present a first population pharmacokinetic (PPK) modeling analysis of Amenamevir for genital herpes patients. The final model retained the effect of Weight and Albumin on CL. Statistical analysis between pharmacokinetics and clinical efficacies was done by using the time above 200 ng/mL (T200 ). T200 derived from the final PPK model to consider the correlation with Time to lesion healing and viral shedding. This finding suggested that it could be necessary to maintain the Amenamevir concentration above the threshold level to prevent the virus replication.

Topics: Antiviral Agents; Drug Administration Schedule; Drug Monitoring; Female; Herpes Genitalis; Herpesvirus 2, Human; Humans; Male; Models, Biological; Nonlinear Dynamics; Oxadiazoles; Recurrence; Treatment Outcome; Viral Load

Current therapies for genital herpes have only partial efficacy. Helicase-primase inhibitors are novel, potent inhibitors of herpes simplex virus replication.. This randomized trial assessed the safety and efficacy of ASP2151 for episodic therapy of recurrent genital herpes. Participants self-initiated with ASP2151 (100, 200, or 400 mg daily for 3 days), ASP2151 (1200 mg as a single dose), placebo for 3 days, or valacyclovir (500 mg twice daily for 3 days). The primary efficacy endpoint, time to lesion healing excluding aborted lesions, was analyzed using a proportional hazards model. Statistical significance was determined by P = .01.. Of 695 adults enrolled, 437 experienced a recurrence and received study drug. Median time for lesion healing excluding aborted lesions was 139.8 hours with placebo, 119.6 hours with ASP2151 (100 mg; hazard ratio [HR], 1.40; P = .065), 106.2 with ASP2151 (200 mg; HR, 1.40; P = .081), 115.9 with ASP2151 (400 mg; HR, 1.25; P = .25), 102.1 with ASP2151 (1200 mg; HR, 1.72; P = .007), and 113.9 with valacyclovir (500 mg twice daily; HR, 1.42; P = .077), indicating improvement in all treatment groups except ASP2151 (400 mg). Incidence of treatment-emergent adverse events was similar across groups.. Three-day or single-day courses of ASP2151 appear to be effective and safe options for treatment of episodes of recurrent genital herpes.. NCT00486200.

Topics: Acyclovir; Adult; Antiviral Agents; Double-Blind Method; Female; Herpes Genitalis; Humans; Male; Middle Aged; Oxadiazoles; Placebos; Treatment Outcome; Valacyclovir; Valine

Amenamevir is a novel drug that targets the viral helicase-primase complex. While dose-dependent efficacy had been observed in non-clinical studies, no clear dose dependence has been observed in humans. We therefore developed a pharmacokinetic/pharmacodynamic (PK/PD) model to explain this inconsistency between species and to clarify the immune-related healing of amenamevir in humans. The model consisted of a non-linear kinetic model for a virtual number of virus plaques as a built-in biomarker. Lesion score was defined as an endpoint of antiviral efficacy, and logit model analysis was applied to the ordered-categorical lesion score. The modeling results suggested the time course profiles of lesion score could be explained with the efficacy terms in the logit model, using change in number of virus plaques as an indicator of the effects of amenamevir and time elapsed as an indicator of the healing of the immune response. In humans, the PD effect was almost dose-independent, and immune-related healing may have been the driving force behind the reduction in lesion scores. Drug efficacy is occasionally masked in diseases healed by the immune response, such as genital herpes. The PK/PD model proposed in the present study must be useful for explanation the PK/PD relationship of such drugs.

Topics: Animals; Antiviral Agents; Cells, Cultured; Chlorocebus aethiops; Female; Guinea Pigs; Herpes Genitalis; Humans; Models, Biological; Oxadiazoles; Recurrence; Simplexvirus; Vero Cells

ASP2151 (amenamevir) is a helicase-primase inhibitor against herpes simplex virus type 1 (HSV-1), HSV-2, and varicella-zoster virus. To evaluate the anti-HSV activity of ASP2151, susceptibility testing was performed on viruses isolated from patients participating in a placebo- and valacyclovir-controlled proof-of-concept phase II study for recurrent genital herpes. A total of 156 HSV strains were isolated prior to the dosing of patients, and no preexisting variants with less susceptibility to ASP2151 or acyclovir (ACV) were detected. ASP2151 inhibited HSV-1 and HSV-2 replication with mean 50% effective concentrations (EC(50)s) of 0.043 and 0.069 μM, whereas ACV exhibited mean EC(50)s of 2.1 and 3.2 μM, respectively. Notably, the susceptibilities of HSV isolates to ASP2151 and ACV were not altered after dosing with the antiviral agents. Taken together, these results demonstrate that ASP2151 inhibits the replication of HSV clinical isolates more potently than ACV, and HSV resistant to this novel helicase-primase inhibitor as well as ACV may not easily emerge in short-term treatment for recurrent genital herpes patients.

Topics: Acyclovir; Antiviral Agents; DNA Helicases; DNA Primase; Enzyme Inhibitors; Herpes Genitalis; Humans; Oxadiazoles; Simplexvirus; Viral Proteins

ASP2151 is a herpesvirus helicase-primase inhibitor with antiviral activity against varicella zoster virus and herpes simplex virus types 1 (HSV-1) and 2 (HSV-2). Here, we examined the potency and efficacy of ASP2151 against HSV in vitro and in vivo. We found that ASP2151 was more potent in inhibiting the replication of HSV-1 and HSV-2 in Vero cells in the plaque reduction assay and had greater anti-HSV activity in a guinea pig model of genital herpes than did acyclovir and valacyclovir (VACV), respectively. Oral ASP2151 given from the day of infection reduced peak and overall disease scores in a dose-dependent manner, resulting in complete prevention of symptoms at the dose of 30 mg/kg. The 50% effective dose (ED(50)) values for ASP2151 and VACV were 0.37 and 68 mg/kg, respectively, indicating that ASP2151 was 184-fold more potent than VACV. When ASP2151 was administered after the onset of symptoms, the disease course of genital herpes was suppressed more effectively than by VACV, with a significant reduction in disease score observed one day after starting ASP2151 at 30 mg/kg, whereas the therapeutic effect of VACV was only evident three days after treatment at the highest dose tested (300 mg/kg). This indicated that ASP2151 possesses a faster onset of action and wider therapeutic time window than VACV. Further, virus shedding from the genital mucosa was significantly reduced with ASP2151 at 10 and 30 mg/kg but not with VACV, even at 300 mg/kg. Taken together, our present findings demonstrated the superior potency and efficacy of ASP2151 against HSV.

Topics: Acyclovir; Animals; Antiviral Agents; Area Under Curve; DNA Helicases; DNA Primase; Drug Evaluation, Preclinical; Female; Guinea Pigs; Herpes Genitalis; Herpesvirus 1, Human; Herpesvirus 2, Human; Oxadiazoles; Valacyclovir; Valine; Viral Load; Viral Plaque Assay; Viral Proteins; Virus Shedding